VLCC级FPSO海上连接的模型试验及虚拟模拟(英文)

阐述了VLCC级.FPSO海上连接的模型试验和虚拟模拟,以及其研究结果如何应用于指导FPSO与SYMS存极浅水中的连接作业.模犁试验和虚拟模拟研究范围覆盖了各安装阶段,包括海上就位试验、就位及连接临时交义缆、系泊腿连接、压载灌浆直至达到风暴安全状态.模型试验不仅可以核实FPSO就何拖拉力要求,而且可以确定FPSO和安装驳船的运动幅值和系泊力大小.而虚拟模拟则可以虚拟模拟环境,通过虚拟模拟确认关键作业人员、作业执行方案和作业程序中潜在的问题.该文介绍的模型试验和虚拟模拟方法可以进一步推广到各种浮式平台的深水应用中.     

Vectorization and constraint grouping to enhance optimization of marine structures

Vectorization converts classical scalar optimization formulation, which strictly separates the objective from constraints, into a vector-based optimization, transforming constraints into objectives. Effectively, the search is not conducted anymore for a single optimum, but for a set of Pareto optima between the original objective and transformed constraints. Constraint grouping enhances handling of multiple constraints for vectorized problems, by combining several constraints within a single-objective function, thus reducing the computational time and computational difficulties of high-dimensional spaces created by vectorization. This paper formulates and investigates these two concepts with respect to design of marine structures. It analyses their effects on the possibility to improve the flexibility of optimization in a practical environment, by implementing them within a simple genetic algorithm. Obtained results of vectorization applied to realistic weight optimization problem are encouraging when compared with the results of the classical scalar form optimization, showing a significant improvement in magnitude as well as in reduced computation time needed to reach the optimum.     

A break-even model for evaluating the cost of container ships waiting times and berth unproductive times in automated quayside operations

The planning, design and development of a container terminal with optimum size and capacity and with a minimum capital cost is fundamentally dependent upon the loading and discharging operations at the quayside. The quayside function of container terminals is dependent basically on the number of berths available to service the incoming container ships. The objective of the container terminals dealing and admitting the ongoing ship calls is to provide immediate berth and loading and discharging services to the container ships with a minimum costly waiting time and a maximum efficiency. Previously terminal planners used to build extra berths to provide service. During the last two decades the terminal operators have adopted automation technologies in loading and discharging operation of the container ships as an alternative to designing extra berths. Ship owners naturally expect least waiting times for their container ships. On the other hand, it is also natural for port operators in a container terminal with costly facilities to see a high berth occupancy and productivity at the quayside. This study uses queuing theory to find a break-even point as a way of evaluating the cost of container ship waiting times and the cost of berth unproductive service times for container terminals aiming to automate their quayside operation. The analysis illustrates that automation devices installed on conventional Quayside Cranes (QSCs) significantly reduce the turnaround time of the container ships calling at the ports. It argues, however, that there should be a balance between the cost of berth unproductive service times and the cost of vessel waiting times. The study introduces a break-even point to be considered as a benchmark for calculating such a balance. The analysis in this study can be used as a decision tool for the operators of container terminals in the medium to small ports to appraise the feasibility of an investment in automation or expansion of the quayside facilities.     

Quantitative assessment of effect of enforcement intensity on violation rates of vehicle weight and dimension regulations

A theory of upper bound limit describing the relationship between maximum possible violation rate as a function of the intensity of enforcement of vehicle weight and dimension regulations and indeed other transport administrative regulations is postulated. The model is an exponential function that determines the maximum violation rate for given inspection capacity. The constant of the function depends on the method of enforcement. The theory is demonstrated to be valid. It has potential for facilitating important policy issues relating to enforcement of transport administrative regulations and within the framework of infrastructure management to be addressed.

The relative effectiveness of enforcement methods is quantified by two parameters namely, the effectiveness index and the truckers’ relative perceived probability of detection. These parameters facilitate evaluation of the performance of various enforcement methods and operation strategies. It is found that patrol teams are, on average, 30 times as effective in detecting violations as continuously operated permanent weigh scales. High perceived detection probabilities are associated with high inspection capacities. To increase the perceived detection probability (reduce violation rates) therefore implies increasing the inspection capacity.     

Transfer penalties: Another look at transit riders' reluctance to transfer

Two on-board surveys were conducted to determine how transit riders perceive transfers. The surveys were conducted before and after the imposition of a transfer in the middle of an existing bus route. Results of the surveys showed that riders perceive bus transit trips as significantly worse when the trip requires a transfer, even if transfer time is neglibible.     

Job satisfaction and personality of Merchant Navy officers

Until recently little research had been carried out into job satisfaction of seafarers. Wastage in the shipping industry is higher than most other industries and although some improvements have been made to working conditions and facilities the wastage is still very high.

During the last two decades shipping technology has changed drastically, necessitated by changing economic factors, resulting in the need for highly trained personnel. Training costs are high, particularly for officers, and could be reduced if efficient selection processes were employed.

The project is designed to study perceived and implied (calculated) job satisfaction of officers who have served in the Merchant Navy for five years or more. Gone are the days of high port-time/sea-time ratios due to increased port and labour costs. Consequently seafarers may be confined together for longer periods at sea such that a different type of personality may be required to survive the stresses and strains of such a way of life. The project also attempted to discover whether the personalitics of the seafaring officers differ from those of the shoreside population and whether personality is related to job satisfaction at sea.

The project took the form of a survey by applying a questionnaire to Merchant Navy deck, engineer and radio officers at nautical educational establishments between September and October 1978.

The results showed that the majority of officers have a moderately high level of perceived job satisfaction whereas implied satisfaction was comparatively low. The personality of officers was found to be significantly different from that of the shoreside population in almost 50% of the 31 personality scales measured. There were also found to be differences between the personalities of deck and engineer officers.

A correlational study indicated that the personality of the Merchant Navy officer is related to overall job satisfaction.     

船队运力过剩的解决方案

我想就航运界普遍担忧的运力过剩问题谈谈自己的看法. 首先来看一组数据:根据克拉克森统计,今年1～10月份全球新接订单合计9512万载重吨,同比增长162%.而截至2010年9月初,油轮、货轮和集装箱船的订单占现有船队的比例分别高达28.5%、54.5%和24.9%.今年1～9月份,中国新船订单5071万载重吨,是去年同期1692万载重吨的三倍.中国承接的新船订单占了全球订单总量的45.6%.航运市场今后如何消化这么庞大的运力?这是航运界需要审慎对待的问题.     

The Application of Roller Rigs to Railway Vehicle Dynamics

Roller rigs have been built world-wide to research into the dynamics of railway vehicles and they have particularly been applied to the development of high-speed trains. This survey takes into consideration both full scale as well as small scale model roller rigs. Besides performance, most important experimental work and the emphasis of application, the scaling strategies of model test rigs and the differences involved in roller rig experiments are treated. Suggestions for potential future uses and developments are also given for this tool which is useful for demonstration and analysis of railway vehicle dynamic behaviour.     

A numerical model of the long term flow along the Malin-Hebrides shelf

A three dimensional hydrodynamic model of the Malin-Hebrides shelf region is used to investigate the spatial variability of the wind and tidally induced residual flow in the region and the influence of flow from the Irish Sea and along the shelf edge. By this means it is possible to understand the spatial variability in the long term observed flow fields in the region and the range of driving forces producing this flow. The model uses a sigma coordinate grid in the vertical with a finer grid in the near surface and near bed shear layers. The vertical diffusion of momentum in the model is parameterised using an eddy viscosity coefficient which is derived from turbulence energy closure models. Two different turbulence models are used to compute the eddy viscosity, namely a two-equation (itq²−q²ℓ) model which has prognostic equations for both turbulence energy and mixing length and a simpler model in which the mixing length is a specified algebraic function of the water depth.The wind induced response to spatially and temporally constant orthogonal wind stresses, namely westerly and southerly winds of 1 N m⁻², are derived from the model. By using orthogonal winds and assuming linearity, then to first order the response to any wind direction can be derived. Computed flows show a uniform wind driven surface layer of magnitude about 3% of the wind speed and direction 15 ° to the right of the wind, in deep water. Currents at depth particularly in the shelf edge and near coastal region show significant spatial variability which is related to variations in bottom topography and the coastline.Calculations show that tidal residual flows are only significant in the near coastal regions where the tidal current is strong and exhibits spatial variability. Flow into the region from the Irish Sea through the North Channel although having its greatest influence in the near coastal region, does affect currents near the shelf edge region. Again the spatial variability of the flow is influenced by topographic effects.A detailed examination of wind induced current profiles together with turbulence, mixing length and viscosity, at a number of locations in the model from deep ocean to shallow near coastal, shows that both turbulence models yield comparable results, with the mixing length in the two equation model showing a similar dependence to that specified in the simpler turbulence model.Calculations clearly show that flow along the shelf edge area to the west of Ireland and from the Irish Sea entering the region, together with local wind forcing can have a major effect upon currents along the Malin-Hebrides shelf. The flow fields show significant spatial variability in the region, comparable to those deduced from long term tracer measurements. The spatial variability found in the calculations suggests that a very intense measurement programme together with inflow measurements into the area is required to understand the circulation in the region, and provide data sets suitable for a rigorous model validation.