Évolution des émissions de CO2 liées aux mobilités quotidiennes: une stabilité en trompe l’œil

Alternatives to the use of automobiles have regained attention at the urban level. Against this background, we look at the spatial context of this attention in the agglomeration of Lyon. More specifically, we look at how CO₂ emissions that are associated with everyday mobility have developed until recently. First, we estimate the intensity of CO₂ emissions per day based on the last two household travel surveys done in the Lyon conurbation in 1995 and 2006. Even if the global emission level remains stable, we aim to analyze the dynamics of the socio-economic evolution of mobility between the two periods. To that end, we have abstracted the linkage of a specific form of mobility (mode of transport and distance) to a specific population group (status, residential location, car access, gender). This typology helps us highlight the groups where emission rates are significantly higher, and where the focus on emission reduction should be intensified.     

Direct method for optimal power management in hybrid electric vehicles

Hybrid electric vehicles are powered by an electric system and an internal combustion engine. The components of a hybrid electric vehicle need to be coordinated in an optimal manner to deliver the desired performance. This paper presents an approach based on direct method for optimal power management in hybrid electric vehicles with inequality constraints. The approach consists of reducing the optimal control problem to a set of algebraic equations by approximating the state variable which is the energy of electric storage, and the control variable which is the power of fuel consumption. This approximation uses orthogonal functions with unknown coefficients. In addition, the inequality constraints are converted to equal constraints. The advantage of the developed method is that its computational complexity is less than that of dynamic and non-linear programming approaches. Also, to use dynamic or non-linear programming, the problem should be discretized resulting in the loss of optimization accuracy. The propsed method, on the other hand, does not require the discretization of the problem producing more accurate results. An example is solved to demonstrate the accuracy of the proposed approach. The results of Haar wavelets, and Chebyshev and Legendre polynomials are presented and discussed.     

One manufacturer's approach to improving jet transport fuel efficiency

In the face of rapidly escalating costs of aircraft fuel, since the early 1970s, the aerospace industry has embarked on a program of measures to reduce fuel consumption. This article describes an integrated set of measures which have been undertaken by Lockheed‐California to improve the fuel requirements of the Tristar, a wide‐bodied three engine medium to long range aircraft. Measures include operational changes, improvements to maintenance practices, long term hardware modifications and technological advances.     

The visual environment of the New York coastal zone: User preferences and perceptions

Abstract

This study examines the opinions and feelings of coastal users along the New York coastal zone to determine if there are attitudinal and perceptional differences with regard to visual quality. The sample of 981 consisted of individuals from the Long Island coastal area and the Great Lakes coastal area. Little regional, attitudinal, and perceptional differences exist. A trend, however, is apparent in that behavior patterns center around preferences for familiar things, a cynical attitude toward public officials, and an avoidance of issues that may tend to overstimulate an already overloaded life style. The indication is that planning considerations on the part of public officials must be cognizant of the personal stance of individuals rather than on their overt actions.     

Sexual risk among female workers on cruise ships

Data were combined from two studies—qualitative interviews with 19 female cruise-ship workers in a Florida port and 192 quantitative interviews conducted with male and female cruise-ship workers in a European and a Florida port. High rates of partner change were reported in the latter sample: 39 % reported two or more sexual partners in the past year. Logistic regression analysis of 16 different variables showed that gender was the variable most strongly independently associated with a new sexual relationship: women were six times more likely than men to report a new private sexual relationship on their last contract (OR 6.20, 95 % confidence interval 2.01–19.09); 39 % of the female crew reported a new private relationship on their last contract, compared to 16 % of the men. Qualitative data suggest some reasons for this gender imbalance: sexual harassment by male superordinates, the taking of a lover for protection from harassment and the liminal character of shipboard life. Parallels are drawn with other studies depicting risk behaviour as situated actions (i.e. shaped by the material and social circumstances in which the action occurs), and with studies which see women’s greater propensity to risk behaviour in some settings as shaped by power relationships.     

Cooperation of Science and Management for Harmful Algal Blooms: Domoic Acid and the Washington Coast Razor Clam Fishery

Harmful algal blooms (HABs) may be increasing in frequency and intensity worldwide. Coastal economies suffer significant income losses when fisheries or beaches are closed to protect human health and subsistence fishing communities are at risk. Despite these hardships, managers must often conservatively close harvests across a wide area or for long periods, because they lack scientific information that would allow them to predict HAB events. The outer coast of Washington State has experienced several closures of the razor clam (Siliqua patula) fishery starting in 1991, due to domoic acid (DA) contamination caused by toxic blooms of the diatom Pseudo-nitzschia. Improved science-based management was needed to minimize the impact of DA on this fishery and the coastal communities that relied on it for income, tourism, and subsistence. The Olympic Region Harmful Algal Bloom (ORHAB) Partnership, comprised of state and tribal managers, scientists, and local stakeholders, evolved in response to this need; it has been successful in its mission. Here we examine ORHAB through the lens of the Institutional Analysis and Development framework, in order to identify key factors contributing to its success. The relevance of our findings for other ORHAB-like institutions in the Pacific Northwest and elsewhere is discussed.     

Management considerations for accreting shorelines

Abstract

Natural coastal accretion in the United States occurs at river mouths, spits across embayments, inlets, capes and cuspate forelands, and pocket beaches. Human‐induced accretion occurs updrift of groins and jetties, landward of breakwaters, and in locations which are artificially nourished. Coastal accretion is usually temporary (years to tens of years). Erosion may occur due to deflection of streams and tidal current channels or to changes in sea level, weather patterns, or sediment budgets. A focus on ownership disputes or use of accreted land draws attention away from the long‐term problem of the development of land which may be subject to future erosion. Control mechanisms should be in place to direct development on accreting shorelines to make more effective use of the resource.     

高举高打的上汽自主战略

可以说,上汽的自主之路走出了自身的特色,对于致力开拓汽车强国之路的各路英雄值得探讨和借鉴。     

An international study on land‐use and transport interaction

This paper underlines the important role played by the interaction between transport and land use in the way cities develop and the need to use a fully integrated land‐use/transport model to assess the longer‐term impacts of urban policies. Since most of the models of this type had never been properly tested, the Transport and Road Research Laboratory in the early 1980s set up a collaborative study to examine critically their performance and to assess the impacts of a range of commonly applied policies.

The paper briefly describes the first phase of the study in which nine models from seven countries were subjected to a rigorous set of tests covering a variety of policies. For practical reasons each model was applied to the city on which it was originally calibrated. To overcome some of the problems of comparison, a second phase of the study was conducted in which some models were applied to several cities each so that the differences due to the particular characteristics of the cities could be identified. In carrying out this phase, some cities were examined by several models and discrepancies in the results analysed. The setting up of the second phase of the study is outlined in this paper, but not the results, which are given in later papers in this and subsequent issues of Transport Reviews.     

Optimization models to characterize the broadcast capacity of vehicular ad hoc networks

Broadcast capacity of the entire network is one of the fundamental properties of vehicular ad hoc networks (VANETs). It measures how efficiently the information can be transmitted in the network and usually it is limited by the interference between the concurrent transmissions in the physical layer of the network. This study defines the broadcast capacity of vehicular ad hoc network as the maximum successful concurrent transmissions. In other words, we measure the maximum number of packets which can be transmitted in a VANET simultaneously, which characterizes how fast a new message such as a traffic incident can be transmitted in a VANET. Integer programming (IP) models are first developed to explore the maximum number of successful receiving nodes as well as the maximum number of transmitting nodes in a VANET. The models embed an traffic flow model in the optimization problem. Since IP model cannot be efficiently solved as the network size increases, this study develops a statistical model to predict the network capacity based on the significant parameters in the transportation and communication networks. MITSIMLab is used to generate the necessary traffic flow data. Response surface method and linear regression technologies are applied to build the statistical models. Thus, this paper brings together an array of tools to solve the broadcast capacity problem in VANETs. The proposed methodology provides an efficient approach to estimate the performance of a VANET in real-time, which will impact the efficacy of travel decision making.