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排序方式: 共有238条查询结果,搜索用时 15 毫秒
101.
A. V. Tumbal N. R. Banapurmath P. G. Tewari 《International Journal of Automotive Technology》2016,17(1):35-50
Increasing petroleum prices, increasing threat to the environment from exhaust emissions and global warming have generated intense international interest in developing renewable and alternative non-petroleum fuels for engines. Evolving feasible technology and recurring energy crisis necessitated a continued investigation into the search for sustainable and clean-burning renewable fuels. In this investigation, Honge oil methyl ester (HOME) was used in a four stroke, single cylinder diesel engine. Tests were carried out to study the effect of fuel injection timing, fuel injector opening pressure (IOP) and injector nozzle geometry on the performance and combustion of CI engine fuelled with HOME. Injection timing was varied from 19°bTDC (before top dead centre) to 27°bTDC in incremental steps of 4°bTDC; injector opening pressure was varied from 210 bar to 240 bar in steps of 10 bar. Nozzle injectors of 3, 4 and 5 holes, each of 0.2, 0.25 and 0.3 mm size were selected for the study. It was concluded that retarded injection timing of 19°bTDC, increased injector opening pressure of 230 bar and 4 hole nozzle injector of 0.2 mm size resulted in overall better engine performance with increased brake thermal efficiency (BTE) and reduced HC, CO, smoke emissions. Further air-fuel mixing was improved using swirl induced techniques which enhanced the engine performance as well. 相似文献
102.
This paper is an initial exploration of inter-industry relationships and linkages in the context of automobile imports to the United States. It is our contention that the nature and structure of the engagement between automobile importers and shipping lines is central to understanding the evolution of the car carrier trade. Building on the literature on transactions costs, and supply and value chains, we show that the regimes currently governing car carriage services range from markets to vertical integration via network forms of engagement. We illustrate this through a detailed discussion of Japanese inter-firm networks and an examination of automobile import data to the US from 1980 to 2000. The findings raise important questions for future research on the impact of inter-industry relationships in various strategic decisions of steamship lines, shippers and port authorities including port entry, port choice and routeing, technological and investment choices, and trajectories of supply chain development. 相似文献
103.
Transportation - Inadequate infrastructure is recognized as an important barrier to cycling; therefore, improvements in the provision of bicycle facilities, such as bikeways, are frequently... 相似文献
104.
105.
Yusuke Tahara Robert V. Wilson Pablo M. Carrica Frederick Stern 《Journal of Marine Science and Technology》2006,11(4):209-228
Steady flow simulations for the Korean Research Institute for Ships and Ocean Engineering (KRISO) container ship (KCS) were
performed for towing and self-propulsion. The main focus in the present article is on the evaluation of computational fluid
dynamics (CFD) as a tool for hull form design along with application of state-of-the-art technology in the flow simulations.
Two Reynolds-averaged Navier-Stokes (RANS) equation solvers were employed, namely CFDShip-Iowa version 4 and Flowpack version
2004e, for the towing and self-propulsion cases, respectively. The new features of CFDShip-Iowa version 4 include a single-phase
level-set method to model the free surface and an overset gridding capability to increase resolution in the flow and wave
fields. The new features of Flowpack version 2004e are related to a self-propulsion scheme in which the RANS solver is coupled
with a propeller performance program based on the infinitely bladed propeller theory. The present work is based on a close
interaction between IIHR-Hydroscience and Engineering of the University of Iowa and Osaka Prefecture University. In the following
article, overviews are given of the present numerical methods and results are presented and discussed for the KCS in towing
and self-propulsion modes, including comparison with available experimental fluid dynamics (EFD) data. Additional evaluation
is provided through discussion of the recent CFD Workshop Tokyo 2005, where both methods appeared to yield very promising
results. 相似文献
106.
107.
Hui Ding Haigen Xu Jun Wu W. J. F. Le Quesne C. J. Sweeting N. V. C. Polunin 《Coastal management》2013,41(5):443-457
Marine ecosystems of the East China Sea are rich in biodiversity, with 12,933 species of which approximately 47.7% are endemic. As anthropogenic impacts are intensifying, fishery resources and biodiversity in the East China Sea are under threat from overfishing, habitat loss, pollution, and biological invasions. Marine protected areas (MPAs) and other spatial management measures are believed useful tools to protect and restore biological resources. Seventeen nature reserves, seven special marine reserves, and three fishery resource conservation zones covering a combined area of 102,156 km2 have so far been established in the Chinese East China Sea in order to protect fishery resources, biodiversity, and marine landscapes. This article provides a review and inventory of MPAs in the Chinese East China Sea as implemented by the People's Republic of China. 相似文献
108.
In the presence of biofilms, stainless steels(SS) exhibits an increase in corrosion potential, called ennoblement. In the present study, the corrosion potential(Ecorr) behavior of the duplex SS UNS S32760 was recorded simultaneously with the in situ marine biofilm formation in two areas at Arraial do Cabo,Southeastern Brazil. The biofilm at Forno Harbor(an anthropogenically disturbed area) was characterized by higher relative abundances of Bacteria at day 2, followed by diatoms(especially Navicula sp.) on day 10 and dinoflagellates on day 18,whereas no clear trend was recorded at Cabo Frio Island(an undisturbed area). The ennoblement of Ecorr values was site-dependent. In a complementary laboratory assay, biofilms were removed and the Ecorr values registered in sterile conditions for the subsequent 10 days and corroborated in situ results. Understanding biofilms and SS interactions has important implications for materials science and engineering decisions as well as helping to fill in important gaps in this knowledge. 相似文献
109.
The Black Sea general circulation is simulated by a primitive equation model with active free surface. The forcing is seasonally variable and is based on available climatic data. The model reproduces the main features of the Black Sea circulation, including the river discharge effects on the mean sea level and the Bosphorus outflow. Model results show that the simulated sea surface elevation increases in spring over the whole sea, reaching a maximum in the Danube delta area. In the same region, a minimum is observed in winter. The amplitude of the seasonal oscillations (about 8–12 cm over the whole basin) is of the same order of magnitude as the maximum horizontal variations (about 15–18 cm between the coastal areas and the basin interior). This strong signal formed mostly by river discharges, along with the seasonal variability in the other forcing functions and the local dynamics creates a well-pronounced interannual variability. The performance of the model in simulating the seasonal and interannual variability is critically analyzed, with a special attention on the cold intermediate water formation and the circulation in the upper 150 m. The simulations demonstrate that the source of intermediate waters is on the shelf, and that the water mass in the core of cold intermediate layer changes with time as a response to the periodic forcing at sea surface. This type of variability is characterized by pronounced interannual changes, proving that important differences could exist between water mass structure in different years, even when using identical atmospheric forcings each year. 相似文献
110.
Efficient estimation of extreme non-linear roll motions using the first-order reliability method (FORM) 总被引:1,自引:0,他引:1
Jørgen Juncher Jensen 《Journal of Marine Science and Technology》2007,12(4):191-202
In on-board decision support systems, efficient procedures are needed for real-time estimation of the maximum ship responses
to be expected within the next few hours, given online information on the sea state and user-defined ranges of possible headings
and speeds. For linear responses, standard frequency domain methods can be applied. For non-linear responses, as exhibited
by the roll motion, standard methods such as direct time domain simulations are not feasible due to the required computational
time. However, the statistical distribution of non-linear ship responses can be estimated very accurately using the first-order
reliability method (FORM), which is well known from structural reliability problems. To illustrate the proposed procedure,
the roll motion was modelled by a simplified non-linear procedure taking into account non-linear hydrodynamic damping, time-varying
restoring and wave excitation moments, and the heave acceleration. Resonance excitation, parametric roll, and forced roll
were all included in the model, albeit with some simplifications. The result is the mean out-crossing rate of the roll angle
together with the most probable wave scenarios (critical wave episodes), leading to user-specified specific maximum roll angles.
The procedure is computationally very effective and can thus be applied to real-time determination of ship-specific combinations
of heading and speed to be avoided in the actual sea state. 相似文献