A cluster analysis approach for differentiating transportation modes using Bluetooth sensor data

A variety of automatic data collection technologies have been used to gather road and highway system data. The majority of these automatic data collection technologies are designed to collect vehicle-based data and either do not have the capability to collect other travel mode data (e.g., bicycles and pedestrians), or may need to be deployed differently to support this capability.

One type of wireless-based data collection system that has been deployed recently is based on Bluetooth technology. A key feature of Bluetooth-based data collection systems that makes travel mode identification feasible is that the Bluetooth-enabled devices within vehicles are also present on bicyclists and pedestrians. This research explores the effectiveness of applying cluster analysis methods when processing data collected via Bluetooth technology from vehicles, bicyclists, and pedestrians to automatically identify the associated travel modes. The results of several experiments utilizing multiple Bluetooth-based data collection units arranged linearly and in relatively close proximity on a simulated intersection demonstrate the potential of cluster analysis to accurately differentiate transportation modes from the collected data.     

Dynamic response of the train–track–bridge system subjected to derailment impacts

Derailments on bridges, although not frequent, when occurs due to a complex dynamic interaction of the train–track–bridge structural system, are very severe. Furthermore, the forced vibration induced by the post-derailment impacts can toss out the derailed wagons from the bridge deck with severe consequences to the traffic underneath and the safety of the occupants of the wagons. This paper presents a study of the train–track–bridge interaction during a heavy freight train crossing a concrete box girder bridge from a normal operation to a derailed state. A numerical model that considers the bridge vibration, train–track interaction and the train post-derailment behaviour is formulated based on a coupled finite-element – multi-body dynamics (FE-MBD) theory. The model is applied to predict the post-derailment behaviour of a freight train composed of one locomotive and several wagons, as well as the dynamic response of a straight single-span simply supported bridge containing ballast track subjected to derailment impacts. For this purpose, a typical derailment scenario of a heavy freight train passing over a severe track geometry defect is introduced. The dynamic derailment behaviour of the heavy freight train and the dynamic responses of the rail bridge are illustrated through numerical examples. The results exhibit the potential for tossing out of the derailed trains from the unstable increase in the yaw angle signature and a lower rate of increase of the bridge deck bending moment compared to the increase in the static axle load of the derailed wheelset.     

MMAS in Belize

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 Belize, which concentrated its effort in the southern portion of the country. The marine managed areas that developed in Belize took a variety of different forms, and involved a number of different government and private sector agencies and organizations.     

穿上波希米亚的郎朗

01.Comme des Garcons波希米亚风西装套装郎朗,一个个冠名第一的衔头一直叫我们刮目相看——他是第一位协同多位指挥家在一个月内连续演奏十大不同风格协奏曲的钢琴家,也是第一位与柏林爱乐、维也纳爱乐、美国五大乐团多次合作的华人钢琴家。在很多公共场合,我们见惯了穿成一本正经高端正装的郎朗,是时候换一换较冒险的心情。     

Design and evaluation of sideslip angle observer for vehicle stability control

This paper presents a method for estimating the vehicle side slip angle, which is considered as a significant signal in determining the vehicle stability region in vehicle stability control systems. The proposed method combines the model-based method and kinematics-based method. Side forces of the front and rear axles are provided as a weighted sum of directly calculated values from a lateral acceleration sensor and a yaw rate sensor and from a tire model according to the nonlinear factor, which is defined to identify the degree of nonlinearity of the vehicle state. Then, the side forces are fed to the extended Kalman filter, which is designed based on the single-track vehicle model associated with a tire model. The cornering stiffness identifier is introduced to compensate for tire force nonlinearities. A fuzzy-logic procedure is implemented to determine the nonlinear factor from the input variables: yaw rate deviation from the reference value and lateral acceleration. The proposed observer is compared with a model-based method and kinematics-based method. An 8 DOF vehicle model and Dugoff tire model are employed to simulate the vehicle state in MATLAB/SIMULINK. The simulation results shows that the proposed method is more accurate than the model-based method and kinematics-based method when the vehicle is subjected to severe maneuvers under different road conditions.     

Application study on a control strategy for a hybrid electric public bus

This paper first describes the control strategy used in a hybrid electric public bus and then proposes a torque-balancing control strategy. Simulations were performed using the designed control strategies, and the results were analyzed under different conditions. The torque-balancing control strategy was improved on the basis of the efficiency-first ideas of the hybrid system. Finally, experiments were performed to verify that the efficiency-first and torque-balancing control strategy (EFCS) is both feasible and reliable. The simulation results showed that, compared with a conventional public bus, the hybrid electric bus could save approximately 27.3 percent on fuel consumption using the EFCS control strategy in a public bus in China, while under the Wuhan urban driving cycle.     

Alternative approaches to spatial modelling

In discussion of the modelling methods that can be used to assess the impacts of transport change on regional and local economies, “land-use/transport interaction (LUTI) models” are often referred to as if all such models were examples of a single, homogeneous commodity. The first and major purpose of this paper is to correct this impression by comparing and contrasting some key features of the main models or modelling packages in the LUTI tradition, particularly those which are generally recognized as constituting the current “state-of-the-art”, or at least the “state of practice”. One particular point within the comparison will be the differing use which is made (or not made) of spatial input-output models in the different approaches.The second purpose of the paper is (more briefly) to compare LUTI modelling with alternative approaches and in particular with spatial computable general equilibrium (SGCE) modelling. One of the common features to emerge from the preceding comparison is that LUTI modelling has been mainly concerned with predicting the location of fixed totals of jobs and of households under different transport scenarios. This is a general feature, even though in some cases these totals are directly fixed by the user whilst in other cases they are the results of long chains of calculations that are insensitive to transport scenarios; in a few cases, the total levels of economic activity are variable according to accessibility-related variables. In contrast, the use of SCGE modelling in testing the impact of transport proposals is very much concerned with the consequences for the total size of the economy in question, usually with a less detailed concern for the spatial distribution of impacts. This comparison leads to a discussion of whether LUTI modelling and SCGE modelling are mutually exclusive or whether some form of synthesis or integration between the two may be theoretically appropriate and/or practically desirable. The requirements of project appraisal - i.e., the assessment of benefits - are also considered.     

European advanced driver training programs: Reasons for optimism

Post license advanced driver training programs in the US and early programs in Europe have often failed to accomplish their stated objectives because, it is suspected, that drivers gain self perceived driving skills that exceed their true skills—leading to increased post training crashes. The consensus from the evaluation of countless advanced driver training programs is that these programs are a detriment to safety, especially for novice, young, male drivers.Some European countries including Sweden, Finland, Austria, Luxembourg, and Norway, have continued to refine these programs, with an entirely new training philosophy emerging around 1990. These ‘post-renewal’ programs have shown considerable promise, despite various data quality and availability concerns. These programs share in common a focus on teaching drivers about self assessment and anticipation of risk, as opposed to teaching drivers how to master driving at the limits of tire adhesion. The programs focus on factors such as self actualization and driving discipline, rather than low level mastery of skills. Drivers are meant to depart these renewed programs with a more realistic assessment of their driving abilities. These renewed programs require considerable specialized and costly infrastructure including dedicated driver training facilities with driving modules engineered specifically for advanced driver training and highly structured curriculums. They are conspicuously missing from both the US road safety toolbox and academic literature. Given the considerable road safety concerns associated with US novice male drivers in particular, these programs warrant further attention.This paper reviews the predominant features and empirical evidence surrounding post licensing advanced driver training programs focused on novice drivers. A clear articulation of differences between the renewed and current US advanced driver training programs is provided. While the individual quantitative evaluations range from marginally to significantly effective in reducing novice driver crash risk, they have been criticized for evaluation deficiencies ranging from small sample sizes to confounding variables to lack of exposure metrics. Collectively, however, the programs sited in the paper suggest at least a marginally positive effect that needs to be validated with further studies. If additional well controlled studies can validate these programs, a pilot program in the US should be considered.     

Embedding risk attitude and decision weights in non-linear logit to accommodate time variability in the value of expected travel time savings

In recent years we have seen important extensions of logit models in behavioural research such as incorporation of preference and scale heterogeneity, attribute processing heuristics, and estimation of willingness to pay (WTP) in WTP space. With rare exception, however, a non-linear treatment of the parameter set to allow for behavioural reality, such as embedded risk attitude and perceptual conditioning of occurrence probabilities attached to specific attributes, is absent. This is especially relevant to the recent focus in travel behaviour research on identifying the willingness to pay for reduced travel time variability, which is the source of estimates of the value of trip reliability that has been shown to take on an increasingly important role in project appraisal. This paper incorporates, in a generalised non-linear (in parameters) logit model, alternative functional forms for perceptual conditioning (known as probability weighting) and risk attitude in the utility function to account for travel time variability, and then derives an empirical estimate of the willingness to pay for trip time variability-embedded travel time savings as an alternative to separate estimates of time savings and trip time reliability. We illustrate the richness of the approach using a stated choice data set for commuter choice between unlabelled attribute packages. Statistically significant risk attitude parameters and parameters underlying decision weights are estimated for multinomial logit and mixed multinomial logit models, along with values of expected travel time savings.     

Cooling effect of methanol on an n-heptane HCCI engine using a dual fuel system

Homogeneous charge compression ignition (HCCI) engines have the potential to raise the efficiency of reciprocating engines during partial load operation. However, the performance of the HCCI engine at high loads is restricted by severe knocking, which can be observed by the excessive pressure rise rate. This is due to the rapid combustion process occurring inside the cylinder, which does not follow the flame propagation that is seen in conventional engines. In this study, a low compression ratio of 9.5:1 for a gasoline engine was converted to operate in HCCI mode with the goal being to expand the stable operating region at high loads. Initially, pure n-heptane was used as the fuel at equivalence ratios of 0.30 to 0.58 with elevated intake charge temperatures of 180 and 90 °C, respectively. The n-heptane HCCI engine could reach a maximum performance at an indicated mean effective pressure (IMEP) of 0.38 MPa, which was larger than the performance found in the literature. To reach an even higher performance, a dual-fuel system was exploited. Methanol, as an anti-detonant additive, was introduced into the intake stream with various amounts of n-heptane at fixed equivalence ratios in the range of 0.42 to 0.52. It was found that the methanol addition cooled the mixture down prior to combustion and resulted in an increased coefficient of variation (COV). In order to maintain stable combustion and keep the pressure rise rate below the limit, the intake charge temperature should be increased. Introduction of 90% and 95% (vol/vol) hydrous methanol showed a similar trend but a lower thermal conversion efficiency and IMEP value. Therefore, a dual fuel HCCI engine could maintain a high thermal conversion efficiency across a wide load and enhance a 5% larger load compared to a pure n-heptane-fuelled HCCI engine. The hydrocarbon (HC) and carbon monoxide (CO) emissions were lower than 800 ppm and 0.10%, respectively. They were less at higher loads. The nitrogen oxides (NO _x ) emissions were below 12 ppm and were found to increase sharply at higher loads to a maximum of 23 ppm.