Sequence-Based Simulation-Optimization Framework With Application to Port Operations at Multimodal Container Terminals

It is evident in previous works that operations research and mathematical algorithms can provide optimal or near-optimal solutions, whereas simulation models can aid in predicting and studying the behavior of systems over time and monitor performance under stochastic and uncertain circumstances. Given the intensive computational effort that simulation optimization methods impose, especially for large and complex systems like container terminals, a favorable approach is to reduce the search space to decrease the amount of computation. A maritime port can consist of multiple terminals with specific functionalities and specialized equipment. A container terminal is one of several facilities in a port that involves numerous resources and entities. It is also where containers are stored and transported, making the container terminal a complex system. Problems such as berth allocation, quay and yard crane scheduling and assignment, storage yard layout configuration, container re-handling, customs and security, and risk analysis become particularly challenging. Discrete-event simulation (DES) models are typically developed for complex and stochastic systems such as container terminals to study their behavior under different scenarios and circumstances. Simulation-optimization methods have emerged as an approach to find optimal values for input variables that maximize certain output metric(s) of the simulation. Various traditional and nontraditional approaches of simulation-optimization continue to be used to aid in decision making. In this dissertation, a novel framework for simulation-optimization is developed, implemented, and validated to study the influence of using a sequence (ordering) of decision variables (resource levels) for simulation-based optimization in resource allocation problems. This approach aims to reduce the computational effort of optimizing large simulations by breaking the simulation-optimization problem into stages. Since container terminals are complex stochastic systems consisting of different areas with detailed and critical functions that may affect the output, a platform that accurately simulates such a system can be of significant analytical benefit. To implement and validate the developed framework, a large-scale complex container terminal discrete-event simulation model was developed and validated based on a real system and then used as a testing platform for various hypothesized algorithms studied in this work

Процедури моделювання логістичних транспортних систем у середовищі мереж Петрі

The article presents the methodology of the logistic system simulation into the Petri Nets environment on the example of agro-products delivery from Ukraine to the Netherlands, as well as a set of case-studies that can be used as didactic means for course “The modeling of transport processes” to teach the future transport industry specialists. The content, features and capabilities of the Petri Nets in the logistics systems simulation have been analyzed. A structural logistic system model of agro-products delivery, which takes into account the operation sequence, the combination peculiarities and the use resources in each subsystem, has been constructed into the Petri Nets. A time criterion has been proposed to determine the effective option for agro-products delivery. According to the results of the logistics system simulation into the Petri Nets environment, a statistical analysis of the parameters has been carried out. It has been made a choice of a suitable option of the delivery scheme allowing for the time spent and the magnitude of the possible costs associated with the use of certain transport modes. It has been made conclusion about feasibility of creating the case-study set, which is based on real facts and being solved into the Petri Nets environment, in order to organize the future transport industry specialists’ study and research activities.У статті представлена ​​методологія моделювання логістичної системи в середовищі Петрі-Мережі на прикладі доставки агропродукції з України до Нідерландів, а також набір тематичних досліджень, які можна використовувати як дидактичний засіб курсу «Моделювання транспортних процесів »для навчання майбутніх фахівців транспортної галузі. Проаналізовано зміст, особливості та можливості мереж Петрі у моделюванні логістичних систем. Модель структурної логістичної системи доставки агропродукції, яка враховує послідовність операцій, особливості поєднання та використання ресурсів у кожній підсистемі, була вбудована в мережі Петрі. Запропоновано критерій часу для визначення ефективного варіанту доставки агропродукції. За результатами моделювання логістичної системи в середовищі мереж Петрі було проведено статистичний аналіз параметрів. Було зроблено вибір відповідного варіанту схеми доставки, що враховує витрачений час та величину можливих витрат, пов'язаних із використанням певних видів транспорту. Було зроблено висновок про доцільність створення набору тематичних досліджень, який ґрунтується на реальних фактах і втілюється в середовище мереж Петрі, з метою організації навчально-дослідницької діяльності майбутніх фахівців транспортної галузі

Optimising the climate resilience of shipping networks

Climate catastrophes (e.g. hurricane, flooding and heat waves) are generating increasing impact on port operations and hence configuration of shipping networks. This paper formulates the routing problem to optimise the resilience of shipping networks, by taking into account the disruptions due to climate risks to port operations. It first describes a literature review with the emphasis on environmental sustainability, port disruptions due to climate extremes and routing optimisation in shipping operations. Second, a centrality assessment of port cities by a novel multi-centrality-based indicator is implemented. Third, a climate resilience model is developed by incorporating the port disruption days by climate risks into shipping route optimisation. Its main contribution is constructing a novel methodology to connect climate risk indices, centrality assessment, and shipping routing to observe the changes of global shipping network by climate change impacts

Modeling Economic Impacts of the Inland Waterway Transportation System

The inland waterway transportation system of the United States (U.S.) handles 11.7 billion tons of freight annually and connects the heartland of the U.S. with the rest of the world by providing a fuel-efficient and environmentally friendly mode of transportation. This dissertation aims to create decision support tools for maritime stakeholders to measure the economic impacts of the inland waterway transportation systems under real world scenarios including disruptions, demand changes, port expansion decisions, and channel deepening investments. Monte Carlo simulation, system dynamics, discrete-event simulation, agent-based modeling, and multiregional input-output modeling techniques are utilized to analyze the complex relationships between inland waterway transportation system components and regional economic impact factors. The first research contribution illustrates that the expected duration of a disruption determines whether decision makers are better off waiting for the waterway system to reopen or switching to an alternative mode of transportation. Moreover, total disruption cost can be reduced by increasing estimation accuracy of disruption duration. The second research contribution shows that without future investment in inland waterway infrastructure, a sustainable system and associate economic impacts cannot be generated in the long-term. The third research contribution illustrates that investing in bottleneck system components results in higher economic impact than investing in non-bottleneck components. The developed models can be adapted to any inland waterway transportation system in the U.S. by utilizing data obtained by publically available sources to measure the economic impacts under various scenarios to inform capital investment decisions and support an economically sustainable inland waterway transportation system

Essays on Port, Container, and Bulk Chemical Logistics Optimization

The essays in this thesis are concerned with two main themes in port logistics. The first theme is the coordination of transport arrivals with the distribution processes and the use of storage facilities. We study this for both containerized and bulk chemical transport. The second theme is the uncertainty associated with the arrival time of ships with bulk chemicals and the impact on port logistics. Each essay describes a case study where quantitative methods, especially simulation, are used. The operation of container terminals and in particular the way in which containers are stacked in a yard is influenced by information about the departure of a container. We find that even inaccurate information is valuable and helps to reduce unproductive moves. Next, we present the ``floating stocks'' distribution concept which uses intermodal transport to deploy inventories in a supply chain in advance of retailer demand. We demonstrate that a main drawback of intermodal transport, a longer transit time, can be mitigated using this concept. This concept also influences the choice of a port: we provide a quantitative interpretation of routing flexibility in port selection

Optimal Planning of Container Terminal Operations

Due to globalization and international trade, moving goods using a mixture of transportation modes has become a norm; today, large vessels transport 95% of the international cargos. In the first part of this thesis, the emphasis is on the sea-land intermodal transport. The availability of different modes of transportation (rail/road/direct) in sea-land intermodal transport and container flows (import, export, transhipment) through the terminal are considered simultaneously within a given planning time horizon. We have also formulated this problem as an Integer Programming (IP) model and the objective is to minimise storage cost, loading and transportation cost from/to the customers. To further understand the computational complexity and performance of the model, we have randomly generated a large number of test instances for extensive experimentation of the algorithm. Since, CPLEX was unable to find the optimal solution for the large test problems; a heuristic algorithm has been devised based on the original IP model to find near „optimal‟ solutions with a relative error of less than 4%. Furthermore, we developed and implemented Lagrangian Relaxation (LR) of the IP formulation of the original problem. The bounds derived from LR were improved using sub-gradient optimisation and computational results are presented. In the second part of the thesis, we consider the combined problems of container assignment and yard crane (YC) deployment within the container terminal. A new IP formulation has been developed using a unified approach with the view to determining optimal container flows and YC requirements within a given planning time horizon. We designed a Branch and Cut (B&C) algorithm to solve the problem to optimality which was computationally evaluated. A novel heuristic approach based on the IP formulation was developed and implemented in C++. Detailed computational results are reported for both the exact and heuristic algorithms using a large number of randomly generated test problems. A practical application of the proposed model in the context of a real case-study is also presented. Finally, a simulation model of container terminal operations based on discrete-event simulation has been developed and implemented with the view of validating the above optimisation model and using it as a test bed for evaluating different operational scenarios

A computer graphics approach to logistics strategy modelling

This thesis describes the development and application of a decision support system for logistics strategy modelling. The decision support system that is developed enables the modelling of logistics systems at a strategic level for any country or area in the world. The model runs on IBM PC or compatible computers under DOS (disk operating system). The decision support system uses colour graphics to represent the different physical functions of a logistics system. The graphics of the system is machine independent. The model displays on the screen the map of the area or country which is being considered for logistic planning. The decision support system is hybrid in term of algorithm. It employs optimisation for allocation. The customers are allocated by building a network path from customer to the source points taking into consideration all the production and throughput constraints on factories, distribution depots and transshipment points. The system uses computer graphic visually interactive heuristics to find the best possible location for distribution depots and transshipment points. In a one depot system it gives the optimum solution but where more than one depot is involved, the optimum solution is not guaranteed. The developed model is a cost-driven model. It represents all the logistics system costs in their proper form. Its solution very much depends on the relationship between all the costs. The locations of depots and transshipment points depend on the relationship between inbound and outbound transportation costs. The model has been validated on real world problems, some of which are described here. The advantages of such a decision support system for the formulation of a problem are discussed. Also discussed is the contribution of such an approach at the validation and solution presentation stages