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991.
At conceptual design stage, automotive body is usually simplified as a frame structure, which consists of thinwalled beams (TWBs). Therefore, the most important issue is to determine the cross-sectional shape of TWBs under the requirement of mechanical properties. However, design engineers mostly depend on their experience or repeated modification to design the cross-sectional shape of TWBs. So this paper presents a rapidly cross-sectional shape design and optimization method to satisfy the demand of mechanical properties and meanwhile minimize the weight of TWB. Firstly, cross-sectional mechanics property formulations are summarized. Especially, the torsional rigidity formulation of three-cell cross section is derived for the first time in this paper. Secondly, the shape optimization model is created to minimize the weight of TWB and improve the mechanical properties, which is solved by genetic algorithm. Moreover, three stamping constraints, draft angle, chamfer radius and assembly, are introduced to promote the cross-sectional shape more practice. Lastly, numerical examples verify the effectiveness of the optimization model and show the application in structural modification of automotive frame.  相似文献   
992.
American subprime crisis has evolved into a global financial crisis, dragging the entire economy, hitting the fictitious economy the most.Under such a situation,the world's investment environment changes inevitably as a result. In talking about the influence of the financial crisis upon China,the most immediate consequence  相似文献   
993.
In this article, the issue of monitoring compliance of State obligations and responsibilities that are derived from them being parties to the various international maritime treaties adopted under the purview of the International Maritime Organization (IMO) will be explored. The genesis of why monitoring compliance of State actors is now topical and the development of the Voluntary IMO Member State Audit Scheme in response thereto will be highlighted. The positive outcome of the audits conducted under the voluntary Scheme and the level of participation of Member States in the Scheme have now brought to the fore the need to consider developing a mandatory audit regime applicable to all Member States of the IMO. In this respect, this article will proffer a possible way forward for the further development of the Audit Scheme.  相似文献   
994.
This paper examines the evolution of urban transport planning since the 1960′s, identifies the key trends that have influenced such planning, describes the current state of urban transport planning, and speculates on the important characteristics that will influence urban transport planning over the next several decades. Fifteen planning conferences since 1957 are reviewed to show the changing perspectives on planning from the professional community. Ten areas are identified that will provide special challenge to future transport planners—demographic changes, the importance of economic production and market forces for transport system performance, multimodal perspectives for transport planning, adopting an operations focus, an important role for technology, developing a sense of community, laying the groundwork for pricing, integrating transport decision making with growth management, transport planning within a sustainability framework, and providing greater accountability of the decision making and planning processes.  相似文献   
995.
Key to the predictive understanding of many nearshore marine ecosystems is the transport of larvae by ocean circulation processes. Many species release thousands to billions of larvae to develop in pelagic waters, but only a few lucky ones successfully settle to suitable habitat and recruit to adult life stages. Methodologies for predicting the larval dispersal are still primitive, and simple diffusive analyses are still used for many important applications. In this study, we investigate mechanisms of larval dispersal using idealized simulations of time-evolving coastal circulations in the California Current system with Lagrangian particles as models for planktonic larvae. Connectivity matrices, which describe the source-to-destination relationships for larval dispersal for a given larval development time course, are used to diagnose the time–space dynamics of larval settlement. The resulting connectivity matrices are shown to be a function of several important time scales, such as the planktonic larval duration, the frequency and duration of larval release events and inherent time scales for the coastal circulations. Many important fishery management applications require knowledge of fish stocks on a year-to-year or generation-to-generation basis. For these short time scales (typically less than 1 year), larval dispersal is generally far from a simple diffusive process and the consideration of the stochastic and episodic nature of larval dispersal is required. This work provides new insights into the spatial–temporal dynamics of nearshore fish stocks.  相似文献   
996.
A method to measure the crosslink density of carbon black was used to analyze the aging behavior of a radiator hose made of carbon black filled EPDM (ethylene-propylene diene monomer) rubber under thermo-oxidative stresses. The crosslink density and the strength of the skin of the rubber specimens initially decreased slightly but then increased over time. The elongation at the break considerably reduced and did not show any similarity to the behaviors of the crosslink density. A possible cause of this reaction might be from the formation of rigid sulphoxide crosslinks and the crosslinks produced by the reaction of unvalcunized sulfurs. Aging the rubber specimens at 180°C caused a slight increase in the crosslink density and a large decrease in tensile strength and elongation. The aging experiment also caused a rapid increase of microhardness in the surface skin region. The formation of carbonyl groups in EPDM molecule chains and the formation of rigid sulphoxide crosslink, rather than the crosslink density variation, may have had a large influence. The changing behaviours of the mechanical properties, molecule chains and crosslinks showed significantly different characteristics in the skin and the interior with aging temperature and time.  相似文献   
997.
This paper proposes to deepen the relationship between mobility and tethering in peri-urban spaces, and provide new methodological avenues, capable of contributing to the build-up of key knowledge elements, that we feel are crucial in a company’s capacity to implement their own sustainability requirements. These key knowledge elements are primarily based on the results stemming from research entitled “Peri-urbanism testing models for living; peri-urban viability, in theory and in practice”. The aim of this research was to assess, at least potentially, the sustainability of periurban spaces, which have seen recent development, as they have benefited from a growing trend towards removing space and time restrictions, through the generalisation of mobility, at the centre of many societal issues today.  相似文献   
998.
This paper presents an application of shallow water theory to describe the motion of floodwater inside a rolling ship in damage condition. The time domain theoretical approach to the coupled problems of ship and water inside compartment motions is briefly described, including the method used to solve for the water motion characteristics and forces exerted on the ship. This approach is applied to the study of the behaviour of a passenger Ro–Ro ship in regular beam seas and numerical results are given for the intact and damaged conditions. Comparison is made with experimental results. For the damaged condition, the characteristics of the floodwater motion are studied in the time domain for a number of different wave frequencies. The shape of the free-surface and phase of water motion in relation to the ship roll motion are shown for several wave frequencies. The dynamic floodwater roll moment is also shown and compared with the static roll moment (flat horizontal free surface), allowing the conclusion that the dynamic roll moment is much larger than the static roll moment, for high wave frequencies, and is in phase opposition in relation to the roll motion.  相似文献   
999.
An Antilock Braking System (ABS) is one of the most important safety facilities equipped in modern vehicles. A self-test is therefore embedded into its ECU to identify any electronic malfunction. However there is no effective method to predict or check its mechanical conditions routinely to ensure its functionality. Because the ABS system is merely actuated above a particular speed in emergency stops, the current brake test facilities are not adequate for ABS test. Because of the dangers involved it would not be acceptable to use a public road to implement such a practice for fault detection so an alternative means must be sought. To provide a safe and convenient solution this paper proposes a novel method to predict ABS faults whilst the vehicle is stationary. In this situation a model-based approach is applied to predict various faults from the ABS, especially from its hydraulic subsystem. As such, a mathematic model is developed to describe the operating processes of ABS including possible faulty conditions. An autonomous control strategy is also designed to actuate the control module independently without the knowledge of the control algorithms embedded in an ABS control module. This approach is evaluated through a Simulink simulation.  相似文献   
1000.
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