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101.
Proshanto K. Mukherjee 《WMU Journal of Maritime Affairs》2007,6(2):147-166
Within the comprehensive body of law encompassed by the International Convention on Safety of Life at Sea, 1974 (SOLAS), there
are two regimes that are topical and outstanding in the current maritime milieu. These are the international safety management
and the international ship and port facility regimes, both characterized by two codes serving as the centre of gravity of
each, namely, the ISM Code and the ISPS Code, respectively. In this article the concept of the code as a legal instrument
is perused following which a critical legal analysis is carried out of the two above-mentioned Codes, including their backgrounds,
the evolutionary process culminating into the regimes and their interrelationships. Several anomalies and inadequacies in
the two regimes are identified but in the final analysis it is concluded that both instruments are salutary additions to the
body of convention law generated by the International Maritime Organization (IMO). They will undoubtedly influence the continuing
development of international law in the field of maritime safety and security. 相似文献
102.
The transport demand in most major cities around the world can only be met with a high‐quality public transport system. The requirements on bus, rail, underground and tram systems are manifold with reliability and efficiency as the key factors. The service operating hours and the size of the network are often extended in order to serve the needs better. Further, most metropolitan areas are trying to provide more incentives for citizens to leave the car at home and use the local transit systems instead. The reasons are well known. Not only does a public transport system only make economical sense if it is well used, but most urban areas with a high car‐dependency face at least three major problems; safety, congestion, and pollution (noise and air pollution, land separation, etc.). It is generally recognised that to decrease car usage and to increase public transport usage a stick & carrot approach is needed. The London congestion‐charging scheme is an example since all revenues collected by the scheme are put into the improvement of bus and underground services. 相似文献
103.
William H. K. Lam Jing Zhou Zhao-han Sheng 《Transportation Research Part B: Methodological》2002,36(10)
This paper proposes a new formulation for the capacity restraint transit assignment problem with elastic line frequency, in which the line frequency is related to the passenger flows on transit lines. A stochastic user equilibrium transit assignment model with congestion and elastic line frequency is proposed and the equivalent mathematical programming problem is also formulated. Since the passenger waiting time and the line capacity are dependent on the line frequency, a fixed point problem with respect to the line frequency is devised accordingly. The existence of the fixed point problem has been proved. A solution algorithm for the proposed model is presented. Finally, a numerical example is used to illustrate the application of the proposed model and solution algorithm. 相似文献
104.
Few marine phytoplankton have heteromorphic life cycles and also often dominate the ecosystems in which they occur. The class Prymnesiophyceae contains a notable exception: the genus Phaeocystis includes three species that form gelatinous colonies but also occur within their ranges as solitary cells. Phaeocystis antarctica and P. pouchetii are exclusively high latitude taxa, and are notable for regionally tremendous blooms of the colony stage. P. globosa occurs circumglobally, yet its colony blooms primarily are confined to colder waters within its range. Three additional species are warm water forms that have been reported only as solitary cells or loose aggregations that bear little resemblance to the organized colonies of the other taxa. Interpretation of existing data indicates that resource availability (light, temperature and nutrients) by itself is not sufficient to explain this distinction between cold-water colony-forming taxa and warm water solitary cell taxa, nor why colony development in P. globosa is essentially a spatially restricted phenomenon within a much broader geographic range. Colony development by P. globosa in situ has been observed at temperatures ≥20 °C, but only rarely and generally under conditions of seasonally or anthropogenically elevated nutrient supply. Data presented here demonstrate colony development at 20–22 °C in natural plankton communities from oligotrophic waters that were pre-screened through 63 μm mesh (i.e. lacking mesozooplankton and large microzooplankton), but not in unscreened communities containing microzooplankton and >63 μm zooplankton. Reduction of colony proliferation at higher temperatures by mesozooplankton grazing remains as an intriguing possibility that is consistent with available evidence to help explain differences in latitudinal extent of in situ colony development. These data are interpreted within a theoretical framework regarding the potential advantages and disadvantages of the two life cycle stages. 相似文献
105.
The influence of food quality on the nutritional metabolism of Acartia clausi was studied experimentally using four different diets: (1) diatom cells of Thalassiosira weissflogii, (2) detritus prepared from the same culture, (3) 50 : 50 mix on a protein basis of the two previous diets, and 4) dinoflagellate cells of Prorocentrum micans. For each trophic, ingestion, gut transit time, trypsin activity and Km (half saturation constant) were measured at limiting and saturating concentration. Assimilation rates were also estimated for both pure diatoms and mixed live–detrital cell diets. Ingestion followed a Holling type 2 response for diets 1 and 4, a linear one for detritus and an intermediate response for diet 3. Gut transit time displayed different adaptive changes with food regime depending on protein concentration. Trypsin activity was lower for detrital food and trypsin Km significantly decreased with increasing concentration of live diatoms. Assimilation rates were higher for live food than for mixed live–detrital food. Results illustrated that Acartia-type copepods optimize nitrogen or protein uptake. They suggest that besides chemoreception-mediated selectivity, internal controls by digestion and assimilation also regulate ingestion (feed-back). 相似文献
106.
A sigma (σ)-coordinate ocean model by Blumberg and Mellor (POM) is applied to study the formation processes of mesoscale cyclones observed in the Eastern Gotland Basin following the dense water inflows. The initial conditions simulate a situation when the Arkona and Bornholm basins and partially the Slupsk Furrow are already filled with the inflow water of the North Sea origin, while the Eastern Gotland and Gdansk basins still contain the old water of pre-inflow stratification. Model runs with constant and time-dependent winds, changing the buoyancy forcing, grid geometry and bottom topography display the following. Entering the Eastern Gotland Basin from the Slupsk Furrow, the bottom intrusion of saline inflow water splits in two: one goes northeast towards the Gotland Deep, and second moves southeast towards the Gulf of Gdansk. An intensive mesoscale cyclonic eddy carrying the inflow water is generated just east of the Slupsk Furrow with the inflow pulse. A number of smaller cyclones with boluses of the inflow water are formed in the permanent halocline along the saline intrusion pathway to the Gotland Deep. Following Spall and Price [J. Phys. Oceanogr. 28 (1998) 1598], the cyclones are suggested to form by the adjustment of the high potential vorticity inflow water column to a low potential vorticity environment. 相似文献
107.
T·K·CEHIEPOB 《国外铁道车辆》2003,40(2):40-43
俄罗斯正在研制新一代车辆并进行车辆检修制度的改革。本文提出标准化工作的前瞻性和综合性,要求车辆与其部件具有等寿命、装卸和调车机械应适应车辆的性能等,这样在铁路行业就会产生巨大的经济效益。 相似文献
108.
Rao V. Dukkipati Renguang Dong 《Vehicle System Dynamics: International Journal of Vehicle Mechanics and Mobility》1999,31(2):95-111
Available experimental data of the dynamic force at a rail joint are used to validate the Discrete Support (DS) model of vehicle-track system. The validated DS model is employed to investigate the characteristics of dynamic forces due to a dipped rail joint. The results show that increasing axle load and rail equivalent mass significantly increases the first peak load. The wheel (unsprung) mass, stiffness of bearing rubber pad, and ballast stiffness mainly affect the second peak load. Properly designing a profile near the rail joint may reduce the dynamic load at the joint. The results obtained also indicate that the dynamic load generated at one wheel partially transmits to a neighboring wheel. 相似文献
109.
Prediction of fatigue life and estimation of its reliability on the parts of an air suspension system 总被引:1,自引:0,他引:1
K. J. Jun T. W. Park S. H. Lee S. P. Jung J. W. Yoon 《International Journal of Automotive Technology》2008,9(6):741-747
Air suspension systems have been implemented in various commercial vehicles, such as buses and special purpose trucks, because
of the comfortable ride and easy height control. An evaluation of the durability of vehicle parts has been required for service
life and safety starting in the early stages of design. The cyclic load applied to the vehicle can cause fatigue failure of
parts, such as the suspension frame. This paper presents a method to predict the fatigue life of the suspension frame at the
design stage of the air suspension system used in a heavy-duty vehicle. To estimate the fatigue life using the SN method,
the Dynamic Stress Time History (DSTH) is necessary for the part of interest. DSTH can be obtained from the results of the
flexible body dynamic analysis using the Belgian road simulation and the Modal Stress Recovery (MSR) method. Furthermore,
the reliability of the predicted fatigue life can be evaluated by considering the variations in material properties. The probability
and distribution of the expected life cycle can be obtained using experimental design with a minimum number of simulations.
The advantage of using statistical methods to evaluate the life cycle is the ability to predict replacement time and the probability
of failure of mass-produced parts. This paper proposes a rapid and simple method that can be effectively applied to the design
of vehicle parts. 相似文献
110.
The characteristics of auto-ignition and micro-explosion behaviors of one-dimensional arrays of fuel droplets suspended in
a chamber with high surrounding temperature were investigated experimentally with various droplet spacings, numbers of droplet
and surrounding temperatures. The fuels used were pure n-decane and emulsified n-decane with varied water contents ranging
from 10 to 30%. All experiments were performed under atmospheric conditions with high surrounding temperatures. An imaging
technique using a high-speed camera was adopted to measure ignition delay, flame lifetime, and flame spread speed. The camera
was also used to observe micro-explosion behaviors. As the droplet array spacing increased, the ignition delay also increased,
regardless of water content. However, the lifetime of the droplet array decreased as the droplet spacing increased. The micro-explosion
starting time remained unchanged regardless of the number of the droplets or the droplet spacing; however, it tended to be
delayed slightly as the water percentage and droplet spacing increased. 相似文献