Optimal handling capacity at a berth

In a recent paper Wanhill [1] described a method for determining the number of berths that should be provided at a port so that the total usage cost would be minimized. However, in many situations a port will provide a single specialized berth to cater for a particular type of cargo; for example, the unloading of iron-ore at a steelworks or the discharge of oil at a general cargo port. The problem then is not one of deciding on the number of berths to be built but rather that of finding the optimal cargo handling capacity for the single berth available. A model is presented in this paper indicating how such a decision may be made, and two examples give approximate lower and upper bounds for the optimal capacity for many practical cases. A second paper will show how a theoretical model often has to be modified in the light of particular circumstances.     

舰船维修系统建模与能力评估(英文)

The authors developed a prototype of a warship maintenance system. The process started by defining the maintenance requirements of warship equipment. Next, a planning scheme was development for a maintenance network. An optimization target for the plan and indexes for assessment were established. Based on the above work, a simulation model was proposed with two layers: a base and a workshop. Dispatching rules were then formulated for the simulation. Experimental results proved the validity of the model and the dispatching algorithm. It was found that the model can solve the capacity evaluation problem for maintenance systems and provides a scientific basis for decision-maker to make decisions regarding equipment maintenance.     

卫星频谱监控系统研究

文章分析了卫星链路在通信过程中出现的问胚,提出了卫星频谱监测系统的设计方案,介绍了对卫星链路测量所需要注意的问题和监测链路性能所使用的主要参数,给出了软硬件系统的构成,对其功能作了详细的分析。该系统的设计可以有效的对现实生活中的卫星通信链路进行保障。     

Power efficient formation configuration for centralized leader–follower AUVs control

Autonomous underwater vehicles (AUVs) have rapidly developed in the last few decades due to their autonomous properties in the investigation of an underwater environment. The goal of this paper is to develop a power efficient formation control for the cooperative motion of AUVs with a support vessel as a leader. In this paper, a kinematic algorithm for the joint motion of an AUV with a support vessel was developed and that algorithm was expanded for the formation of AUVs. The AUV yaw, surge and sway control loops were designed for that purpose. The complexing navigation system structure for the AUV was also developed. Simulation results demonstrated efficiency of the proposed kinematic algorithm for the joint motion of AUVs. Also, influence of lateral ocean current was considered. After development of the centralized leader?Cfollower formation control for the group of AUVs with a support vessel as a leader, we optimized a formation configuration in terms of power efficiency. Drag forces caused by AUV motion in the water can significantly influence power consumption. We investigated the relationship between the AUV's formation configuration, underwater coverage efficiency, communication quality and power consumption. As a result of research, we proposed a power efficient formation configuration for typical underwater operations. As a result, the effect of the AUV formation configuration on the power consumption was investigated and a trade-off solution for the optimal AUV positions in formation with minimal energy consumption, high coverage efficiency and small communication power consumption was derived.     

舰船1301灭火系统事故分析

自20世纪60年代至今的40年中,以卤代烷1301为灭火剂的灭火系统,以其优越的灭火性能及其在舰船上的特别适用性,目前仍为各国海军所普遍使用。文章通过分析某船1301灭火系统事故个案,对该船1301灭火系统的工作原理、事故原因进行了全面分析和验证,并提出改进方案。     

Design of bridges against ship collisions

The paper outlines a rational design procedure for bridge piers and pylons against ship collision impacts. Firstly, a set of risk acceptance criteria are proposed. This is followed by a mathematically based procedure for calculation of the probability of critical ship meeting situations near the bridge, and the probability of ship collision accidents caused by human errors as well as technical errors. This first part of the paper leads to identification of the largest striking ship, “design vessels”, a given bridge pier must withstand without structural failure in order for the bridge connection to fulfil the risk acceptance criteria. The final part of the paper is devoted to an analysis of the needed impact capacity for the bridge pylons and piers exposed to ship bow impact loads from these “design vessels”. For a number of different ship types and different tonnage merchant vessels, load – displacement relations for ship bow collisions against rigid walls are derived. Based on these comprehensive numerical results, a new empirical relation is derived which is suited for design against bow collisions. This expression for maximum bow collision forces is compared with a previously published expression for ice-strengthened ships and with existing standards for assessment of bow crushing forces. It is shown that there is need for an update of these existing standards. For design of piers and pylons against local impact pressure loads, a pressure - area relation for bulbous bow impacts is derived.     

从"亚平"轮事故谈海上安全应急信息共享机制的建立

为切实保障海洋公共交通安全,建立海上安全应急信息共享机制已经迫在眉睫。本文认为,要打破“信息孤岛”现象,建立相互依存、有机联系、实用高效的海上安全应急信息共享机制,就必须加强四个系统建设,包括建设高效的指挥系统、密切的协同系统、完备的技术系统、长效的反馈系统。同时,本文提出,要发挥海事部门在海上安全应急信息共享机制中的主导作用,切实保障海洋公共交通安全。     

在FIDIC合同下进行施工索赔的关键环节及注意事项

索赔对承包商来说是一项艰巨且重要的任务.文章对FIDIC合同下索赔的关键环节和注意事项及步骤进行初步探析,其关键环节包括索赔原由和依据及索赔注意事项,为工程承包商提供参考.     

Cruise ship market segmentation: a 'non-traditional' port case study

Market segmentation in the cruise ship industry is an essential tool for securing a favourable market share. A case study of a mid-sized vessel operating from a 'non-traditional' port provides insights of the demographic and socio-economic characteristics of a cruise population. The questionnaire also supports the logic for a strong local/regional marketing effort and validates the rationale for the provision of a cruise service from a 'non-traditional' port.     

沿海客箱船主尺度的确定

本文首先定义了一个这和船等级评定标准，建立了应用神经网络理论估算客（货）船造价和客舱（位）平均面积的模型，据此编制了确定客箱船主尺度的程序系统，并给出了优选客箱船主尺度的计算例子。     

A survey on modeling and control of thruster-assisted position mooring systems

This review presents a systematic summary of the state-of-the-art development of technological solutions, modeling, and control strategies of thruster-assisted position mooring (TAPM) systems. The survey serves as a starting point for exploring automatic control and real-time monitoring solutions proposed for TAPM systems. A brief historical background of the mooring systems is given. The kinematics and a simplified kinetic control-design model of a TAPM system are derived in accordance with established control methods, including a quasistatic linearized model for the restoring and damping forces based on low-frequency horizontal motions of the vessel. In addition, another two mooring line models, i.e., the catenary equation and the finite element method model, are presented for the purpose of higher-fidelity simulations. The basic TAPM control strategies are reviewed, including heading control, surge-sway damping, roll–pitch damping (for semisubmersibles), and line break detection and compensation. Details on the concepts of setpoint chasing for optimal positioning of a vessel at the equilibrium position are discussed based on balancing the mooring forces with the environmental loads and avoiding mooring line failure modes. One method for setpoint chasing is the use of a structural reliability index, accounting for both mean mooring line tensions and dynamic effects. Another method is the use of a lowpass filter on the position of the vessel itself, to provide a reference position. The most advanced method seems to be the use of a fault-tolerant control framework that, in addition to direct fault detection and isolation in the mooring system, incorporates minimization of either the low-frequency tensions in the mooring lines or minimization of the reliability indices for the mooring lines to select the optimal directions for the setpoint to move. A hybrid (or supervisory switching) control method is also presented, where a best-fit control law and observer law are automatically selected among a bank of control and observer algorithms based on the supervision of the sea-state and automatic switching logic.     

An overview of buckling and ultimate strength of spherical pressure hull under external pressure

The load-carrying capability of spherical shells under external pressure has been the subject of a long history and many theoretical and experimental studies have been carried out. However, from a comparative study on the design rules for the minimum thickness of the deep manned spherical shells from various classification societies, significant differences have been found. This indicates that these design rules need to be updated and unified like Common Structural Rules for tankers and bulk carriers. In order to lay a foundation for this target, a systematic study is carried out to develop a consistent calculation method for predicting the ultimate strength of spherical pressure hull under external pressure. This is the first paper of a series of three for reporting this study and in this paper, a critical review on the buckling and ultimate strength of spherical pressure hulls is carried out and further problems to be studied are identified. This could lay a solid foundation for the further study.     

Reduction of VIV using suppression devices—An empirical approach

Helical strakes are known to reduce and even eliminate the oscillation amplitude of vortex-induced vibrations (VIV). This reduction will increase the fatigue life. The optimum length and position of the helical strakes for a given riser will vary with the current profile.

The purpose of the present paper is to describe how data from VIV experiments with suppressing devices like fairings and strakes can be implemented into a theoretical VIV model. The computer program is based on an empirical model for calculation of VIV. Suppression devices can be accounted for by using user-defined data for hydrodynamic coefficients, i.e. lift and damping coefficients, for the selected segments.

The effect of strakes on fatigue damage due to cross flow VIV is illustrated for a vertical riser exposed to sheared and uniform current. Comparison of measured and calculated fatigue life is performed for a model riser equipped with helical strakes. A systematic study of length of a section with strakes for a set of current profiles is done and the results are also presented.     

Optimal handling capacity at a berth

In a recent paper Wanhill [1] described a method for determining the number of berths that should be provided at a port so that the total usage cost would be minimized. However, in many situations a port will provide a single specialized berth to cater for a particular type of cargo; for example, the unloading of iron-ore at a steelworks or the discharge of oil at a general cargo port. The problem then is not one of deciding on the number of berths to be built but rather that of finding the optimal cargo handling capacity for the single berth available. A model is presented in this paper indicating how such a decision may be made, and two examples give approximate lower and upper bounds for the optimal capacity for many practical cases. A second paper will show how a theoretical model often has to be modified in the light of particular circumstances.     

甲醇燃料的船用发动机对空气排放的测量（英文）

Emissions of exhaust gases and particulate matter from a dual fuel marine engine using methanol as fuel with marine gasoil as pilot fuel have been examined for a ferry during operation. The emission factor for nitrogen oxides is lower than what is typically found for marine gasoil but does not reach the tier III limit. The emissions of particulate matter are significantly lower than for fuel oils and similar to what is found for LNG engines. The main part of the particles can be found in the ultrafine range with the peak being at around 18 nm. About 93% of the particles are evaporated and absorbed when using a thermodenuder, and thus a large majority of the particles are volatile. Methanol is a potential future marine fuel that will reduce emissions of air pollutants and can be made as a biofuel to meet emission targets for greenhouse gases.     

Is there potential for a two-tier tanker market?

The simulations performed show that demand for quality tankers has to increase by 30% for a two-tier tanker market to emerge. The two-tier freight structure will only last for 3-5 years due to contracting induced by higher freight rates. This means that OPA does not by itself result in higher freight rates for tankers that comply with the requirements. If Western Europe also closes their trades to substandard tankers, a two-tier market emerges and quality tankers obtain a premium. The paper presents a simulation model for international tanker markets. The non-linear complementary equilibrium model solves for a sequence of static equilibria in segmented tanker freight markets, shipbuilding and scrapping markets. Freight markets are segmented according to quality requirements for tankers. The model specifies three tanker classes and one quality tankers can operate both market segments.     

空间扭面钢箱梁制造技术

结合景观人行桥纽带型扭面空间结构连续梁的特点,介绍钢箱梁整体采用反造、翻身复胎的匹配方式、精确控制梁段线形的制造方法。施工工艺的不断优化,使本工程钢箱梁的制造工艺突破了传统的预拼装技术,保证了施工质量,提高了生产效率,节约了制造成本。     

波斯湾中受随机波作用的某新建离岸导管架平台时域动力分析研究（英文）

API RP2 A WSD is a design code in practice for design of jacket platforms in the Persian Gulf but is based on the Gulf of Mexico environmental condition. So for the sake of using this code for the Persian Gulf, it is better to perform a calibration based on this specific region. Analysis and design of jacket platforms based on API code are performed in a static manner and dynamic analysis is not recommended for such structures. Regarding the fact that the real behavior of the offshore jacket platforms is a dynamic behavior, so in this research, dynamic analysis for an offshore jacket platform in the Persian Gulf under extreme environmental condition is performed using random time domain method. Therefore, a new constructed offshore jacket platform in the Persian Gulf is selected and analyzed. Fifteen, 1-h storm, simulations for the water surface elevation is produced to capture the statistical properties of extreme sea condition. Time series of base shear and overturning moment are derived from both dynamic and static responses. By calculating the maximum dynamic amplification factor(DAF) from each simulation and fitting the collected data to Weibull distribution, the most probable maximum extreme(MPME) value for the DAF is achieved. Results show that a realistic value for DAF for this specific platform is 1.06, which is a notable value and is recommended to take into practice in design of fixed jacket platform in the Persian Gulf.     

Incorporated probability that a fleet meets a given permissible value for the hull girder section modulus loss

The paper presents a study on the incorporated probability that a tanker fleet meets a given permissible value of hull girder strength loss. The analysis was based on a database of hull girder section modulus (HGSM) for as-gauged girth belts of tankers. It was found that its mean value is below 5% over the entire life span of the analyzed tanker fleet. The Weibull probabilistic distribution was found to best represent the time-varying HGSM loss. A method was developed for calculating the incorporated safety of a fleet. As an example, the IMO requirement for a maximum HGSM reduction of 10% relative to its required value was analyzed, accounting for time-variant HGSM loss and including a probabilistic model for coating longevity. The views expressed in the paper are those of the authors and not necessary those of ABS.     

Some aspects of the structural design of a mat foundation for various soil conditions

There are several important structural design parameters in the analysis of a mat type structure for a jackup mobile offshore drilling unit. These consist of dimensions for the mat, soil foundation types, and structural loads. Methods for determining the proper dimension of the mat structure, modeling the structure and its loading cases, modeling the soil conditions and a method for identifying critical load cases for each element and load case is presented. By using a database approach for the finite element output for all of the various loading cases, a rational approach is presented which solves the problem of sorting and analyzing all of the elements and load cases, ensuring that all are included and none of the critical cases are missed.