Simulation-based performance evaluation of transport vehicles at automated container terminals

Significant unproductive and costly waiting occurs during AGV (Automated Guided Vehicle) use, both under the CC (Container Crane) and in the blocks compared to that of a manual yard tractor. A possible solution to this problem is that, in the design of ACT (Automated Container Terminals), ALV (Automated Lifting Vehicles), which can load and unload their own containers, be considered as an alternative. In this paper, the objective is to analyze how increases in the use of ALVs rather than AGVs affects the productivity of ACTs. We derived four inferences regarding the cycle time of vehicles and verified their validity in a simulation. A simulation model of an ACT with perpendicular layout was developed and is described in this paper. From the results of the simulation analysis, we determined the savings effect by cycle time and the required number of vehicles. We demonstrated that the ALV is superior to the AGV in both productivity and efficiency principally because the ALV eliminates the waiting time in the buffer zone.Correspondence to: Yong Seok Choi:     

A unified set of resequencing algorithms

A general algorithm for resequencing equations and finite element meshes is presented. This algorithm incorporates, in a unified form, the most successful resequencing schemes, namely: the Sloan, Gibbs–King (GK) and Gibbs–Poole–Stockmeyer (GPS) algorithms. As well it provides a context within which the development of new algorithms may take place with a minimum of change. It is easily programmed and has been shown to speed up the execution of the original GK algorithm.     

Data for a unified theory of transport processes

The author has proved that Darcy's law is not dependent on the laws of Fick or Newton being a transport law that includes mechanical work.     

Comparing transportation systems for inter-terminal transport at the Maasvlakte container terminals

In this paper, a comparison between three transportation systems for the overland transport of containers between container terminals is presented. A simulation model has been developed to assist in this respect. Transport in this study can be done by either multi-trailers, automated guided vehicles or automated lifting vehicles. The model is equipped with a rule-based control system as well as an advanced planning algorithm. The model is applied to a realistic scenario for the Maasvlakte situation in the near future. The experiments give insight into the importance of the different characteristics of the transport systems and their interaction with the handling equipment. Finally, a cost analysis has been executed to support management investment decisions.     

Operations research at container terminals: a literature update

The current decade sees a considerable growth in worldwide container transportation and with it an indispensable need for optimization. Also the interest in and availability of academic literatures as well as case reports are almost exploding. With this paper an earlier survey which proved to be of utmost importance for the community is updated and extended to provide the current state of the art in container terminal operations and operations research.     

A unified set of single step algorithms. Part 2: Theory

Part 1 of this paper¹ presents a very general single step algorithm SSpj for the numerical integration of first and second order time dependent differential equations. In Part 2 we present and discuss results of the accuracy and stability analysis for SS11, SS21, SS31, SS22 and SS32. There is also a detailed comparison of SS22 and the Newmark algorithm.     

Performance analysis of berth configurations at container terminals

The containerized trade market has been growing rapidly since its introduction. The capacity of ships and the amount of containers being transshipped at container terminals increases significantly. Terminals should handle their operations efficiently to provide the necessary capacity and customer service. In designing a container terminal, terminal management has to consider the choice for a certain type of berth. In this paper, we compare by means of a simulation study the performance of traditional one-sided marginal berths and indented berths. An indented berth enables quay cranes to unload and load containers from both sides of the ship. As a result, more quay cranes can work on a single ship. As main performance measure in this comparison we use the total vessel operation time required to unload and load a ship. This time depends next to crane productivity also on the efficiency of the transportation and storage and retrieval processes in the terminal. We have performed a sensitivity analysis in which we also study the relation between the selection of an indented berth and other design and control issues in the terminal.     

Molecular transport at a moving surface at low pressures

The rate of impingement and departure and the differential forces exerted by molecules at a moving surface in a low pressure gas are considered theoretically. Expressions for these quantities, assuming accomodation at the surface or no accommodation and assuming either specular of diffuse scattering, are derived. It is shown that in general the differential pressure exerted by a gas is either equal to or lower, under all circumstances, than the values derived earlier for specular reflexion no accomodation conditions, indicating that the details of the surface collisions cannot account for observed discrepancies between experimental measurements and theoretical predictions.     

论城市公共信息导向系统标准化

一、城市公共信息导向系统我们说公共信息是公众在公共场所行动需要了解的信息,包括场所地点信息、服务功能信息、行为提示信息等,如旅游场所、宾馆饭店、购物、医疗、教育、行路、驾车信息等等。城市公共信息导向系统是引导人们在某个城市内的任何公共场所进行活动的信息系统。该系统在恰当的位置,以最佳的方式提供人们需要的公共信息。完善的导向系统应达到这样一种目的,即一个外地人甚至外国人初临一个城市后,借助导向系统的指引能够容易地到达其目的地,这期间复杂信息的获得依赖于由导向系统指引的问讯处或信息中心。该系统将一个城市看…     

Access to public information: a scientometric study of legal versus voluntary transparency in the public sector

Scientometrics - The aim of this study is to identify, synthesise and evaluate the current state of research into transparency in the public sector, with respect to the period 2005–2014, in...     

A unified set of single step algorithms part 3: The beta-m method,a generalization of the Newmark scheme

Introduced herein is a generalization of Newmark's time marching integration scheme, called the β-m method. Like the SSpj method (introduced in Parts 1 and 2 of this series), the β-m method provides a gcneral single-step scheme applicable to any set of initial value problems. The method is specialized by specifying the method order m along with rn integration parameters, β0, β1, …, β_m?1. For a particular choice of m, the integration parameters provide a subfamily of methods which control accuracy and stability, as well as offering options for explicit or implicit algorithms. For the most part, attention is focused on the application to structural dynamic equations. Most well-known methods (e.g. Newmark, Wilson, Houbolt, etc.) are shown to be special cases within the β-m family. Hence, one computationally efficient and surprisingly simple algorithm unifies old and new methods. Stability and accuracy analyses are presented for method orders m = 2, 3 and 4 to determine optimal parameters for implicit and explicit schemes, along with numerical verification.     

A unified set of single step algorithms. Part 1: General formulation and applications

A general algorithm for a single step time marching scheme for use in dynamic or diffusion equations is presented. This algorithm is easily programmed in its universal form for all orders of approximation and covers most of the currently used schemes as well as presenting many new possibilities. In many cases it presents a computationally advantageous form over conventional procedures—this is particularly so when compared with the Newmark algorighm and its variants.     

Economy of information in congested transport systems

Emerging communication and information technologies increasingly enable users of transport systems to determine their own whereabouts and help support their trip scheduling and rescheduling decisions by providing timely information on traffic conditions. The authors investigate the linkages between behavioural attitudes of users towards risk and valuation of information, by utilising decision-theoretic and risk management principles and extensive-form game trees. Several examples are provided to demonstrate the increase in expected value and steps that should be encountered in the provision of travel information, with particular emphasis on multi-modal transport systems with congestion effects.     

Reductions in transport mortality in Australia: Evidence of a public health success

Objective

To describe trends in transport mortality for a range of common transport types in Australia over a 30-year period (1975–1977 to 2005–2007).

Methods

Mortality data on all-cause and transport-related causes of death were supplied by the Australian Institute of Health and Welfare (AIHW). Mortality rates, expected number of deaths and probabilities of death were compared for three time periods: 1975–1977, 1990–1992 and 2005–2007.

Results

There were significant decreasing trends between 1975–1977 and 2005–2007 in all-cause and most other transport mortality types for both men and women. There were significant reductions in the contribution of transport-related mortality to all-cause mortality; however the difference in mortality between men and women (higher for men) changed little over the evaluated period.

Conclusions

Between 1975–1977 and 2005–2007 there were marked reductions in key causes of transport-related mortality amongst Australian adults, and the reductions in transport-related mortality exceeded reductions in all-cause mortality. The reductions could be attributed to better preventive measures and improved medical treatment for people involved in transport crashes. Although there is scope for further improvement, the reductions are evidence of a success in the prevention of crashes and the medical treatment of crash victims.     

Analytical representation of a surface defined only at a discrete set of points

Interpolation of a curved triangular surface element by a complete cubic polynomial that minimizes C¹discontinuity is described.     

Use of patent information at a Czechoslovak research institute

This article describes the patent information services in Czechoslovakia and the use made of patent information in applied research and in patent practice. The various possibilities which exist centrally, regionally and in industry are discussed.     

Deadlock handling for real-time control of AGVs at automated container terminals

In automated container terminals, situations occur where quay cranes, stacking cranes, and automated guided vehicles (AGVs), directly or indirectly request each other to start a specific process. Hence, all of the affected resources are blocked, possibly leading to the complete deadlock of individual cranes or AGVs. Particularly, AGVs are liable to deadlocks because they always need a secondary resource, either a quay crane or a stacking crane, to perform the pick-up and drop-off operations. Because usually no buffering of containers takes place at the interfaces between AGVs and cranes, the consequences of deadlocks are rather severe. Two different methods for the detection of deadlocks are presented. One is based on a matrix representation of the terminal system. The other directly traces the requests for the individual resources. To resolve deadlock situations arising in an automated container terminal, three different procedures are proposed. These procedures aim to modify the sequence of handling operations or to assign them to alternative resources so that conflicts between concurrent processes are resolved. The suitability of the concept is demonstrated in an extensive simulation study.     

Mathematical modelling of container transfers and storage locations at seaport terminals

This paper models the seaport system with the objective of determining the optimal storage strategy and container-handling schedule. It presents an iterative search algorithm that integrates a container-transfer model with a container-location model in a cyclic fashion to determine both optimal locations and corresponding handling schedule. A genetic algorithm (GA), a tabu search (TS) and a tabu search/genetic algorithm hybrid are used to solve the problem. The implementation of these models and algorithms are capable of handling the very large problems that arise in container terminal operations. Different resource levels are analysed and a comparison with current practise at an Australian port is done.