Fleet deployment optimization models.Part 2

The fleet deployment problem for the one origin,one destination fixed-price contract requiring the transport of a given total amount of cargo within a given period is formulated and solved for the case that one or more cost components are given staircase functions of time. A computer program has been developed to implement the solution of this problem. The fleet deployment problem with one or more costs being random variables with known probability density functions is also formulated. Analytical expressions for hte basic probabilistic quantities, i.e the probability density function,the mean and the variance of the total operating cost, are presented. Finally, sample results are presented and discussed and some extensions for further research are suggested.     

Fleet deployment optimization for liner shipping Part 2. Implementation and results

We use linear programming (LP) for solving the problem of the optimal deployment of an existing fleet of multipurpose or fully containerized ships, among a given set of routes, including information for lay-up time, if any, and type and number of extra ships to charter, based on a detailed and realistic model for the calculation of the operating costs of all the ship types in every route and on a suitable LP formulation developed in earlier work of the authors. The optimization model is also applicable to the problem of finding the best fleet compostion and deployment, in a given set of trade routes, which may be the case when a shipping company is considering new or modified services, or a renewal of the existing fleet. In addition, two promising mixed linear-integer programming formulations are suggested.     

Fleet deployment optimization for liner shipping Part 1. Background, problem formulation and solution approaches

The background and the literature in liner fleet scheduling is reviewed and the objectives and assumptions of our approach are explained. We develop a detailed and realistic model for the estimation of the operating costs of liner ships on various routes, and present a linear programming formulation for the liner fleet deployment problem. Independent approaches for fixing both the service frequencies in the different routes and the speeds of the ships, are presented.     

Fleet deployment optimization for liner shipping: an integer programming model

Extending and improving an earlier work of the second author, an Integer Programming (IP) model is developed to minimize the operating and lay-up costs for a fleet of liner ships operating on various routes. The IP model determines the optimal deployment of an existing fleet, given route, service, charter, and compatibility constraints. Two examples are worked with extensive actual data provided by Flota Mercante Grancolombiana (FMG). The optimal deployment is solved for their existing ship and service requirements and results and conclusions are given.     

Tactical planning models for managing container flow and ship deployment

This paper addresses two practical problems from a liner shipping company, i.e. the container flow management problem and the ship deployment problem, at the tactical planning level. A sequential model and a joint optimisation model are formulated to solve the problems. Our results show that the company should implement the joint optimisation model at the tactical planning level to improve the shipping capacity utilisation rather than the sequential model used in the current practice. Repositioning empty containers also need to be considered jointly with the nonempty container flow at the tactical planning level. Some important managerial insights into the operational and business processes are gained.     

雷达网优化部署效能评估仿真系统研究

针对雷达网优化部署效能评估仿真系统可以模拟雷达网方案的部署,自动地计算出雷达网各项战术指标,而且能对雷达网的部署方案进行分析、评估和优化,从而选取最优方案.阐述了雷达网优化部署效能评估系统的组成,建立了雷达网效能评估指标体系,以及仿真系统的实现过程.结果表明,该系统的实现为雷达指挥所指挥员和作战参谋提供了雷达组网方案的辅助分析,提高了指挥所在多种战术背景下的快速反应能力和整体作战指挥能力.     

宁波航标处人力资源配置优化实证分析

为推动我国港航业发展,充分发挥人力资源的作用,针对上海海事局宁波航标处人力资源结构的现状,分析其中存在的年龄、学历、专业和技术职称等方面的问题,提出满足海事局人才发展需要的人力资源结构优化措施。     

Hydrodynamic hull form optimization using parametric models

Hydrodynamic optimizations of ship hull forms have been carried out employing parametric curves generated by fairness-optimized B-Spline form parameter curves, labeled as F-Spline. Two functionalities of the parametric geometry models are used in the present study: a constrained transformation function to account for hull form variations and a geometric entity used in full parametric hull form design. The present F-Spline based optimization procedure is applied to two distinct hydrodynamic hull form optimizations: the global shape optimization of an ultra-large container ship and the forebody hull form for the hydrodynamic optimization of an LPG carrier. Improvements of ship performance achieved by the proposed F-Spline procedure are demonstrated through numerical experiments and through correlations with experimental data. The ultra-large containership was built and delivered to the ship owner. The present study validates the effectiveness of the proposed hydrodynamic optimization procedure, ushering in process automation and performance improvement in practical ship design practices.     

一种舰艇编队区域防空效能评估方法

舰艇编队的区域防空作战是一个复杂问题,而对其效能评估又涉及大量难以量化的因素,且因素间存在多重相关性。主成分分析正是适宜解决这一难题的方法论,它可通过将相关性很高的变量转化成彼此独立或不相关的变量,有效降低维度,最终达到数据化简、揭示变量间的关系和进行数据解释的目的。建立了舰艇编队区域防空作战效能评估模型,运用主成分分析法对该模型的多项指标进行综合聚集,最后以编队区域防空作战训练评估为例,验证该模型方法的科学性与可行性。     

Part 2. Beyond single-outcome models: Decompositions of aggregate and disaggregate road safety risk

The second part of the state-of-the-art focuses on the development of the founders' double streams explaining single-outcome indicators (probability of accidents and fatalities, respectively) by fixed form regression, as outlined in the Part 1. Following Page (1997, pp. 67–122, 2001) and others, we use as turning point of the evolution of both aggregate and discrete approaches the DRAG-1 model of 1984, itself based on aggregate data, which introduced four key innovations in principle applicable to both streams.     

Emerging organizational values in shipping: Part 1. Crew stability

In this paper, Smith and Roggema examine the solutions emerging in answer to the growing concern in North European shipping companies to adapt to increasing competition and technological diversity and also to attract and retain suitably qualified seafarers. Part 1 describes a move from a situation of lack of stability of crew towards greater crew stability, whilst Part 2 discusses the redistribution of responsibility on board ship, encompassing a change from the caste-like division between officers and ratings and a more flexible division of functions and authority.     

Part 3. Multivariate road safety models: Future research orientations and current use to forecast performance

The third part of the state-of-the-art focuses on the future of road safety modeling and on conjectures concerning the evolution of national safety indicators. In the absence of econometric developments specific to road safety modeling, the research future must rely on pre-existing statistical procedures of econometrics applied to discrete/count and to aggregate data. In terms of contents, growing interest in the heterogeneity of road accident outcomes by category of victims could lead to treatments of this issue across research streams, say by top-down and bottom-up developments, but this speculation does not rest on extant adequate formulations of the issue of road user class and victim analysis. But understanding the time profile of aggregate national performance indicators is quite another matter.     

Analysis of the accident of the MVNakhodka. Part 1. Estimation of wave loads

MVNakhodka collapsed and broke in two on January 2, 1997 in the Sea of Japan, giving rise to a serious and disastrous oil spill on the coastline of Japan. During the inquiry into the cause of the accident, one of the main tasks of the inquiry committee was to identify the external loads which made the ship structure collapse. Among the several possible scenarios for the accident, after careful examination, the wave loads in the heavy weather at the time of the accident were taken to be the most plausible cause. The results of that research are described in two papers, and the present paper deals with the way in which wave loads on theNakhodka at the moment of the accident were estimated. We first describe the details of the accident such as the location, the sea condition, the loading condition, and the ship's heading speed. Then the static loads resulting from the distribution of the cargo weight and the buoyancy are given to show that the static bending moment at the time of the accident caused extreme sagging. Next the wave loads in the irregular waves, calculated by the nonlinear time domain simulation program SRSLAM, are presented. It is shown that the bending moment in the waves reaches 1 087 800 KN^*m at maximum SS 6.9, which is where the hull girder collapse took place. It was concluded that the ship broke in two because the bending moment exceeded the hull girder strength which had been reduced due to corrosion, taking into account conclusions derived from the research dealing with the structural strength aspect. We also discuss the stochastic significance of the estimated value and nonlinear nature of the peak distribution, in addition to the effects of the ship speed and wave heading on the wave load estimation. This article is based on an article that appeared in Japanese in the Journal of the Society of Naval Architects of Japan, vol. 183 (1998).     

Scantling optimization based on convex linearizations and a dual approach—Part II

The development of the LBR-5 “Stiffened Panels Software” is included in the development of a new design methodology to ease and to improve preliminary studies of naval structures and floating hydraulic structures. It allows, as of the first draft, an optimization of the scantling of the structure's constituent elements. The ultimate target is to link standard design tools (steel structure CAD, hull form, hydrostatic curves, floating stability, weight estimation, etc.) with a rational optimization design module and a minimum construction cost (or minimum weight) objective function. It is developed to be a user-oriented tool. The optimization module is composed of three basic modules (OPTI, CONSTRAINT and COST) and a group of sub-modules (in external databases). Among these the user selects a set of relevant sub-modules (i.e. geometrical and structural constraints). Since the present optimization deals with least construction costs (as objective function), and uses an explicit objective function (not empirical), the user must specify labor costs (unitary material costs, welding, cutting, etc.). This paper is the second part of a series of two articles. The previous paper focused on the ‘Module-Oriented Optimization’ methodology and on the rational constraints (Rigo, Marine Structures 2001). This paper presents the optimization algorithm based on convex linearization and a dual approach (OPTI module). It also includes the optimization of a FSO unit as a detailed example.     

The British port transport industry Part 1. Operational structure, investment and competition

Abolition of the National Dock labour Scheme in July 1989 has intensified competition in Britian's ports and allowed the major port authorities and other port operators to restructure their operations and develop new investment plans. But the result has been to add to excess capacity in the industry and to porduce a 'zero-sum' process of traffic redistribution between Britain's driven largely by customer demands for lower charges.     

Hydrodynamics of a body floating in a two-layer fluid of finite depth. Part 1. Radiation problem

A linearized 2-D radiation problem was considered for a general floating body in a two-layer fluid of finite depth. A boundary integral-equation method was developed for directly computing the velocity potential on the wetted surface of a body which is immersed in both the upper and lower layers as a general case. To do this, appropriate time-harmonic Greens functions were derived, and an efficient numerical method of evaluating those functions is proposed. Based on Greens theorem, hydrodynamic relations such as the energy-conservation principle were derived theoretically for a case of finite depth, and we confirm that those relations are satisfied numerically with very good accuracy. Experiments were also carried out using water and isoparaffin oil as the two fluids and a Lewis-form body. Measured results for the added mass, the damping coefficient, and the amplitude of the generated waves are compared with the computed results, and a favorable agreement is found.     

Carrier selection in a RO/RO ferry trade Part 1. Decision factors and attitudes

The choices faced by shippers are generally complex. Typically, the shipper is presented with a range of alternative carriers, each of which has its individual strengths and weaknesses. A survey of companies purchasing shipping services in an overnight RO/RO ferry trade was conducted to identify their priorities and to help understand and the decision-making process. The shippers were found to be conservative decision makers with a strong emphasis on quality of service.     

Cargo handling productivity. Part 2. The findings

This is the second of two papers on cargo handling productivity presenting the results of the model developed int he first [1] which had been designed to test a productivity measurement method with cross-sectional empirical data. Four productivity measures were employed. Two related cargo handling to time, with labour brought into the analysis as an independent variable. The third productivity measure expressed total throughput as an aspect of labour productivity, while the final measure was a full productivity index developed by relating output to both capital and labour.

The productivity measurement technique demonstrated that this method can be used for cross-sectional studies and can cope with and allow for variation in non-controllable extraneous factors, thus proving useful for policy decision-makers in shipping lines and/or port authorities.

This paper presents the results of the prodictivity analysis for which the analytical design was decribed in Part 1. The first section briefly restates the productivity indices developed. The principal results and tests on these measures are present in Section 2 with conclusion following in Section 3.