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761.
作为燃料有几个优势,其中包括储量充足和价格低廉。但是没有“清洁煤”这种说法。除了煤烟、有毒化学品,以及金属外,燃煤电厂每千瓦小时放出的二氧化碳也比燃烧石油或天然气的电厂要多。煤在空气中燃烧时不可避免地产生二氧化碳。因此煤是一种问题燃料,不仅在于它引发气候变化,而且影响到人类健康和安全问题。  相似文献   
762.
The influence of intrusions of eastern North Atlantic central water (ENACW) in the north and northwestern Iberian shelf on phytoplankton composition and abundance and on particle-size distributions of seston was analyzed using data collected on three extensive cruises during spring 1991 and 1992. Water with temperature and salinity values between 12.20 and 13.86 °C and between 35.66 and 35.98 psu, respectively, characteristics of the subtropical type of ENACW (ENACWt), was detected in the upper 100 m of the water-column in all cruises, but particularly in the western coast in 1992. The highest salinity values of this water were found near the surface (0–100-m depth) and in early spring 1992, while minimum salinity values, and also minimum geographical extension, were found in late spring in both years. Phytoplankton blooms concentrated in frontal areas between different water types, with maximum intensity and extension in early spring.Using temperature and salinity characteristics, samples were classified in four groups corresponding to the major water types found in the region: Bay of Biscay central water (BBCW), two segments of ENACW of different salinity and surface water influenced by continental runoff. This classification was significantly confirmed by three independent discriminant analyses using hydrographic and chemical (dissolved nutrients and chlorophyll) variables, phytoplankton species abundance variables and particle-size concentration of seston variables. Phytoplankton blooms related to the presence of saline waters were characterized by the dominance of either chain-forming diatoms or a mixture of diatoms and phytoflagellates and high concentrations of seston. The diatom species dominating in saline waters were typical of upwelling-induced blooms occurring generally during summer. Blooms occurring in waters influenced by runoff also contained diatoms but in lower numbers than those of saline waters. Nutrients were not exhausted in the region, suggesting that phytoplankton populations were still in active growth. These results are interpreted taking into account the known variability in water-mass formation and in the poleward current driving ENACWt along the shelf, and indicate that saline intrusions are a major feature affecting the distribution and composition of plankton in the spring in the southern Bay of Biscay, thus enlarging to a wider spatial scale their reported influence on the pelagic ecosystem.  相似文献   
763.
介绍了一种三点式恒频独立变流器,它使用一个耦合电感器来实现整个系统和负载范围内主开关的零电压开关.因为耦合电感器在负载电流回路中并不作为一个串联电感出现,所以它在输出整流管上并不造成负载循环损耗.在1 kW样机上验证了推荐的变流器工作情况和性能.  相似文献   
764.
765.
Summary In this paper, the sensitivity analysis is applied to the development of high performance adaptive hydraulic mounts. The analysis allows us to select the most effective design parameters for tuning an adaptive mount to different road and engine conditions. It is shown that in the low frequency road excitation, the upper chamber compliance and inertia of the fluid column in the inertia track are the most influential properties in changing the dynamic stiffness of the hydraulic mount. These properties for the high frequency engine excitations are the upper compliance and the inertia of the fluid column of the decoupler. For tuning the adaptive mount to different road and engine excitation, a global optimization technique is used to find the magnitude of the adjusting parameters to minimize objective functions in low and high frequency excitations. The results indicate significant improvement over conventional hydraulic mounts. It is further shown that when the upper compliance is used as the adjusting parameter, a simple on-off control which is triggered by the engine revolution and vehicle speed is sufficient for tuning the adaptive mount.  相似文献   
766.
Summary Each vehicle on a section of highway is potentially a driving condition 'sensor.' For example, a vehicle's speed give can give a clue about the traffic conditions in its section of roadway. By 'cooperative estimation,' we mean a system that uses a communication network to combine the experience of many vehicles into parameter estimates that are more useful than the estimates that any individual vehicle could generate by itself. This paper demonstrates the cooperative estimation concept by showing how it can be used to estimate traffic conditions and road friction without using roadside sensors.  相似文献   
767.
This paper discusses the factors that determine the utility of a mode and attempts to suggest and investigate a novel fuzzy measure based solution approach to the problem of multimodal analysis in a multicriteria context. The paper expands on the notions of fuzzy logic and in particular, fuzzy measures. The approach attempts to estimate the probabilities of the “overall system” from a group of eight experts who are experienced in transport planning. The data is used to ascertain the relative utility of various modes in a competitive environment. It explains the application of fuzzy measures to provide guidance information for a transport planning agency.  相似文献   
768.
The objective of this study is to propose the indices which detect the deviated state of drivers while driving by considering drivers’ judgment process and using road environment and naturalistic driving behavior database. To realize this objective, drivers’ speed choice behavior around curve situations was focused and the speed choice process was formulated. Moreover, a deviated state detection method considering the formulated speed choice process around curve situations was proposed and the validity of the method was examined.  相似文献   
769.
Industrial organizations have increasingly sought to optimize the resources needed for the manufacture of its products from the competition, in order to maintain their profit margins. The search for balance of resources and balanced distribution of tasks in various types of industrial environments is called balancing. When adjustments are made and adequacy of an assembly line that is already in operation, this process is called rebalancing. This paper presents a case study involving a problem of rebalancing of automotive assembly line in an environment of arbitrarily mixed models of products, also known as mix. The proposed procedure for solving the rebalancing in the company in question is based on Binary Integer Programming, in particular the branch and bound algorithm. For comparison, we used a heuristic method based on precedence diagrams for solving the rebalancing of lines. To evaluate the results obtained between the two procedures were used performance indicators such as number of workstations created, average load of work and level of unbalance. The proposed algorithm has resulted in significant improvements in the production line capacity.  相似文献   
770.
This article describes the international regime governing compensation for oil pollution damage from ships. It sets out the main features of the relevant international Conventions, the Civil Liability Conventions and the Fund Conventions, and explains the operations of the International Oil Pollution Compensation Funds, their structure and financing. The procedure for settlement of compensation of claims is outlined and a summary is made of the criteria for the admissibility of claims for compensation. The ongoing review of the international compensation regime is described.  相似文献   
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