Morphology and oxidation kinetics of CI engine’s biodiesel particulate matters on cordierite Diesel Particulate Filters using TGA

The impact of small compression ignition (CI) engine operation conditions and fuel properties on diesel and biodiesel particulate matters (PMs) quantity using opacity smoke meter is investigated. The biodiesel engine’s PMs are around a half of diesel engine PMs under the same engine operation conditions. Morphology of both engine’s PMs are also studied using a Scanning Electron Microscopy (SEM), Transmission Electron Microscopy (TEM) and image processing method. The average primary nanoparticle sizes of diesel and biodiesel engine’s PMs are approximately 34 nm and 32 nm, respectively. The result shows that engine operation condition and fuel property are strongly impact on the quantity and size distribution of primary nanoparticles emission. PM oxidation kinetics on conventional cordierite Diesel Particulate Filters (DPFs) powders by Thermo-gravimetric analysis (TGA) is also successfully studied. The calculated apparent activation energies of biodiesel engine’s PM oxidation on conventional cordierite DPFs powders are lower than that of diesel engine’s PM and carbon black because of unburned oxygenated molecule. The calculated apparent activation energy of biodiesel engine’s PM and diesel engine’s PM oxidize on conventional cordierite DPFs powders with pure air are in the range of 109 ~ 131 kJ/mole and 117 ~ 130 kJ/mole, respectively. It might be expected that smaller primary nanoparticle size of biodiesel engine’s PMs and bio-oxygenate unburned hydrocarbon can promote more PM oxidation rate during vehicle’s DPF regeneration process.     

VirMaLab — atelier virtuel de maintenance: un outil d’aide à la décision pour l’optimisation des politiques de maintenance

This article deals with a generic approach called VirMaLab (virtual maintenance laboratory) for reliabilitybased maintenance modeling for complex systems (with multi-components and multi-states). Based on the probabilistic graphical models formalism (also known as Bayesian networks), this stochastic approach takes into account both the degradation process of the considered system (an original semi-Markovian model is proposed) and maintenance strategies (from diagnosis factors to all kinds of maintenance actions). For complete decision support tools, cost parameters should also be considered (maintenance actions, unavailability of the system, running, etc.). In this article, two applications of this approach to rail maintenance are introduced. The first one focuses on the optimization of the compromise refurbishment/repairing of central part of the RER A line. The second one focuses on the comparison and evaluation of various maintenance strategies in the modernization of the command control systems of Paris metro lines.     

A time-use investigation of shopping participation in three Canadian cities: is there evidence of social exclusion?

Increasing awareness and concern about the status of mobility-disadvantaged groups in society has given rise to a wide body of research that focuses on the social exclusion dimension of transportation. To date, much of the empirical work on this topic is mainly spatial in nature despite recent developments that call for the inclusion of time use analyses in social exclusion research. In this paper we attempt to fill this gap by estimating activity and trip durations to determine whether poverty, old age, or being a single parent results in time use patterns indicative of exclusion. Given the importance of shopping and using services for social inclusion objectives, these activities are the focus of this investigation. In terms of methods, use of a multiple equation approach allows for the estimation of the daily duration of shopping activities and trips while simultaneously controlling for daily durations of four broad categories of activities as well as their associated travel times. The results indicate: that being a senior citizen increases travel durations while decreasing shopping activity durations; that coming from a low income household decreases shopping activity durations; and single-parent status does not impact shopping activity durations when holding income and other activity durations constant. These results highlight the feasibility and challenges of time-use and activity analysis in social exclusion research.     

Torque ripple minimization control of permanent magnet synchronous motors for EPS applications

This paper identifies a control method used to reduce torque ripple of a permanent magnet synchronous motor (PMSM) for an electric power steering (EPS) system. NVH (Noise Vibration Harshness) is important for safe and convenient driving. Vibration caused by motor torque is a problem in column type EPS systems. Maintaining a very low torque ripple is one solution that allows for smoother steering. Theoretically, it is possible to design and drive the motor without torque ripple. However, in reality, a PMSM system torque ripple is caused by the motor itself (saturation in the iron core and EMF distortion) and the imperfect driver. This paper analyzes torque ripple of a PMSM system, and an advanced PMSM control method for the column typed EPS system is presented. Results of the analysis indicate that the compensation current is needed in order to minimize torque ripple when a PMSM is driven.     

基于GIS的道路热区鉴别方法

基于地理信息系统以及热区基本模型,研究了道路热区的鉴别方法。该方法对道路网依据一定优先权进行合并以获取道路基本单元,模拟了交通事故的空间分布,并采用Monte Carlo法定义各道路基本单元交通事故数阈值,通过检验道路基本单元的空间邻近性得到热区,并对上海世博园周边道路热区进行了鉴别。分析结果表明:道路网经合并后,不规则道路基本单元的百分比由41.5%下降到14.8%;世博园周边共有84个仅涉及车辆、33个涉及行人的热区,与实际相符。可见,该方法能有效鉴别道路危险区域。     

Changes in Swiss accessibility since 1850

This paper discusses the changes in Swiss accessibility since 1850 after arguing that such spatially detailed measures are needed, if one wants to understand the impact of transport investment on the economy and land use patterns.The road-based accessibility overtook that offered by the railways around 1930 and has kept a steady relative lead since then. The relative advantage of the large cities has been eroded since 1950 through their population loss and the massive population gain of the metropolitan fringe. In absolute terms, though, they are still locations with the highest accessibilities.     

Assessment of IACS-CSR implicit safety levels for buckling strength of stiffened panels for double hull tankers

The present study aims at applying structural reliability methods to assess the implicit safety levels of the buckling strength requirements for longitudinal stiffened panels implemented in the IACS Common Structural Rules (CSR) for double hull oil tankers. The buckling strength requirements considered are used in the initial stage of the hull girder scantlings’ design to control the buckling capacity of longitudinal stiffened panels subjected to the compressive loads induced by the hull girder vertical bending. The following buckling collapse failure modes are explicitly considered in the design formulation: uniaxial buckling of the plating between stiffeners, column buckling of stiffeners with attached plating and lateral-torsional buckling or tripping of stiffeners.The paper presents the procedure used to assess the implicit safety levels of the strength requirements for the three buckling collapse failure modes above mentioned, which includes the optimization of the scantlings of the plate panels and longitudinal stiffeners in order to reflect the minimum strength required by the formulation. A first order reliability formulation is adopted, and stochastic models proposed in the literature are used to quantify the uncertainty in the relevant design variables. A sample of five oil tankers representative of the range of application of the IACS-CSR design rules is considered. The effect of corrosion in the implicit safety levels is quantified based on the three corrosion levels of the Net Thickness Approach (NTA) adopted in the design rules. Sensitivity analyses are also performed to quantify the relative contribution or importance of each design random variable to the implicit safety levels.     

Customization of Automatic Incident Detection Algorithms for Signalized Urban Arterials

Non-recurrent congestion or incidents are detrimental to the operability and efficiency of busy urban transport networks. There exist multiple automatic incident detection algorithms (AIDAs) to remotely detect the occurrence of an incident in highway or freeway scenarios; however, very little research has been performed to automatically detect incidents in signalized urban arterials. This limited research attention has mostly been focused on developing new urban arterial specific algorithms, rather than identifying alternative methods to synthesize existing freeway-based algorithms for urban conditions. The main hindrance to such synthesis is that the traffic patterns on the signalized urban arterials are significantly different from the same on highways/freeways due to the presence of traffic intersections. This article introduces a new strategy of customizing the existing AIDAs (freeway based or otherwise) to significantly improve their adaptability to signalized urban arterial transport networks. The new strategy focuses on preprocessing the traffic information before being used as input to a freeway/highway-based AIDA to lessen the effect of traffic signals and to imitate the input patterns in highway/freeway-based incident conditions. The effectiveness of this new strategy has been established with the help of four existing AIDAs. The proposed strategy is a simple solution to implement existing algorithms to signalized urban networks without any further instrumentation or operational cost.     

Discerning the operational state of a vehicle’s distributed electronic systems from vehicle network traffic for use as a fault detection and diagnosis tool

This paper suggests a novel approach to finding faults in a vehicle’s electronic systems by monitoring the network traffic directly and generating statistical traits. The nature of the data in a CAN network is considered, and a case for the use of statistical analysis presented. Statistical traits extracted from the temporal behavior of network messages are investigated as a metric for fault detection. It is shown how this trait information can be extracted from network data, and how this information could be used for fault detection of an unknown fault on a CAN network. It is then demonstrated that combining multiple types of trait data can be used to correctly identify a fault once detected.