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521.
液化气船事故频发的根源及对策 总被引:1,自引:0,他引:1
近年来,国内液化气船恶性事故接连不断,已严重危及液化气海上运输事业的发展.而要遏制这种趋势,必须准确分析事故频发的根源并采取有力措施. 相似文献
522.
The research on biomass reduction of Fe2O3 was carried out by using sawdust as reductant. The direct reducing agents in the biomass magnetization process were determined by comparing various biomass pyrolysis products with the reduction degree (divalent iron content in total iron), reduction temperature range and valence change of Fe2O3 in the reduction process. The microstructure variation of Fe2O3 at different stages was also analyzed by scanning electron microscopy (SEM). Nonisothermal thermogravimetric analysis (TGA) was applied to explore the thermal reduction process. The results show that the direct reducing substances in the biomass reaction with Fe2O3 are H2 and bio-oil, and the reduction process can be divided into two steps: biomass pyrolyzing to release H2 and bio-oil, and reductive volatiles reacting with Fe2O3. The two steps are relatively independent. The kinetic of the reduction reaction follows a first-order reaction kinetic model, with 88.99 kJ/mol activation energy and 9.55 × 108 min?1 frequency factor. 相似文献
523.
Urban travel demand, consisting of thousands or millions of origin–destination trips, can be viewed as a large-scale weighted directed graph. The paper applies a complex network-motivated approach to understand and characterize urban travel demand patterns through analysis of statistical properties of origin–destination demand networks. We compare selected network characteristics of travel demand patterns in two cities, presenting a comparative network-theoretic analysis of Chicago and Melbourne. The proposed approach develops an interdisciplinary and quantitative framework to understand mobility characteristics in urban areas. The paper explores statistical properties of the complex weighted network of urban trips of the selected cities. We show that travel demand networks exhibit similar properties despite their differences in topography and urban structure. Results provide a quantitative characterization of the network structure of origin–destination demand in cities, suggesting that the underlying dynamical processes in travel demand networks are similar and evolved by the distribution of activities and interaction between places in cities. 相似文献
524.
Ibrahim S. Seddiek 《Journal of Marine Science and Technology》2016,21(3):493-500
Strategies of fuel consumption onboard ships are of one of the crucial issues in marine shipping industry. Many of the relevant authorities maritime domain gave great interesting to that issue, either through research that discussed the impact of marine fuel consumption on the environment and economy of ships or through practical experiments’ that are made by marine engine manufacturers. Over the years, many solutions have been put forward to overcome this problem while maintaining the amount of goods transported globally at the same transfer rate and ship speed. The present paper sheds light on many of the methods used currently to reach this purpose. It is explained that applying a certain fuel-saving strategy will rely on some of the factors, especially the type of ship. Mainly two methods including: shore-side power and cold out of heat strategies have been investigated regarding adaption, economic, and environmental issues in case of applying onboard high-speed passenger ships. 相似文献
525.
Myung-Seop Lim Dong-Min Kim Jung-Pyo Hong 《International Journal of Automotive Technology》2017,18(3):499-504
This paper deals with the speed response characteristic of the concentrated flux synchronous motor (CFSM) using ferrite magnets for the electric power steering (EPS) system. To analyze the response characteristic of the CFSM, an analytical method using the electromechanical undamped natural frequency and damping ratio based on the transfer function is proposed. By using the method, the speed response according to the variations of the shape of the permanent magnets (PMs) and rotor core is analyzed. It was analyzed under the conditions of the constant volume of the PMs as well as the constant diameter of the rotor. By using the proposed analysis method, the improved model is desgined based on the initial model fulfilling the required specifications. Finally, the torque and speed response characteristics of two motors are simulated through the finite element analysis (FEA) and MATLAB Simulink. 相似文献
526.
A large-sized tactical wrecker is a special-purpose vehicle that lifts and tows tactical vehicles and heavy loads. It consists of a crane, a post structure, outriggers and a suitable chassis truck, and during its initial design, the structural safety and tipping stability should be preemptively examined in terms of the layout of these components. This paper proposes computer-aided engineering (CAE) methods to evaluate the maximum lifting capacity of the wrecker and the structural safety of its crane during the initial design. The analytical model for the large-sized wrecker is constructed with 236 degrees of freedom by combining the crane system developed using the ADAMS macros with the dynamic model of large chassis truck with an axle suspension. The design parameters for the wrecker model that influence the tipping stability are selected, and then the maximum lifting loads with the corresponding changes are calculated. This parametric study shows that the characteristics of the boom and the layout of the outriggers greatly affect the maximum lifting capacity. Finite element (FE) analyses of the 1st stage boom and the 3rd stage boom show the stresses under the maximum overturning moment condition are within the allowable strength. 相似文献
527.
In this paper, we present an ontology-based approach for legal provision retrieval. The approach aims at assisting the man
who knows little about legal knowledge to inquire appropriate provisions. Legal ontology and legal concept probability model
are main functional components in our approach. Legal ontology is extracted from Chinese laws by the natural language processing
(NLP) techniques. Legal concept probability model is built from corpus, and the model is used to bridge the gap between legal
ontology and natural language inquiries. 相似文献
528.
Association analysis is an effective data mining approach capable of unveiling interesting associations within a large dataset.
Although widely adopted in e-business areas, it still has many difficulties when applied in practice. For instance, there
is a mismatch between the static rules discovered and the drifting nature of the user interests, and it is difficult to detect
associations from a huge volume of raw user data. This paper presents an effective approach to mine evolving association rules
in order to tackle these problems. It is followed by a recommendation model based on the evolving association rules unveiled.
Experimental results on an online toggery show that it can effectively unveil people’s shifting interests and make better
recommendations accordingly. 相似文献
529.
530.
Zhong Chang Liu Xing Yuan Jing Tian Yong Qiang Han Kai Bo Yu Peng Kun Teng 《International Journal of Automotive Technology》2018,19(5):783-794
The object of this paper is to reduce soot emissions under typical 5s transient conditions of constant speed and increasing torque. And effects of fuel injection timing on combustion and emissions parameters were experimentally and numerically studied in a regulated two-stage turbocharged diesel engine with a turbine bypass valve (TBV). The test results indicated that: the smaller TBV opening could improve deterioration of smoke emissions and BSFC at medium and heavy loads. Afterward, the full-stage injection timing (FSIT) strategies (delaying injection timing during the entire transient process) could reduce soot and NOX emissions simultaneously. However, when TBV opening became larger, smoke emissions and BSFC were deteriorated gradually. Moreover, the sectional-stage injection timing (SSIT) strategies (advancing injection timing from 10 % load to a preset load and delaying injection timing from the preset load to 100 % load) could markedly reduce soot emissions by 75.8 % with TBV opening 20 %; the degradation of fuel consumption could be effectively suppressed. Finally, coupling the SSIT strategies with the TBV control strategies could significantly improve the transient performance. 相似文献