Novel approaches to container loading: from heuristics to hybrid tabu search

A thesis submitted for the degree of Doctor of Philosophy of the University ofBedford shireThis work investigates new approaches to the container loading problem which address the issue of how to load three-dimensional, rectangular items (e.g. boxes) into the container in such a way that maximum utilisation is made of the container space. This problem occurs in several industry sectors where the loading approach places cargo effectively into aeroplanes, ships, trailers or trucks in order to save considerable cost. In carrying out this work, the investigation starts by developing a new heuristic approach to the two-dimensional bin packing problem, which has lower complexity than container loading in the aspects of constraints and geometry. A novel approach, including the heuristic strategies and handling method for remaining areas, is developed that can produce good results when testing with benchmark and real world data. Based on the research for two-dimensional bin packing, a novel heuristic approach is developed to deal with the container loading problem with some practical constraints. The heuristic approach to container loading also includes heuristic strategies and the handling of remaining spaces. The heuristic strategies construct effective loading arrangements where combinations of identical or different box types are loaded in blocks. The handling method for remaining spaces further improves the loading arrangements through the representation, partitioning and merging of remaining spaces. The heuristic approach obtains better volume utilisation and the highest stability compared with other published heuristic approaches. However, it does not achieve as high a volume utilisation as metaheuristic approaches, e.g. genetic algorithms and tabu search.To improve volume utilisation, a new hybrid heuristic approach to the container loading problem is further developed based on the tabu search technique which covers the encoding, evaluation criterion and configuration of neighbourhood and candidate solutions. The heuristic strategies as well as the handling method for remaining spaces developed in the heuristic approach are used in this new hybrid tabu search approach. It is shown that the hybrid approach has better volume utilisation than the published approaches under the condition that all loaded boxes with one hundred per cent support from below. In addition, the experimental results show that both the heuristic and hybrid tabu search approaches can also be applied to the multiple container loading problem

Analysis of factors affecting crossdock operations using computer simulation.

Wong, Wing Shuet.Thesis (M.Phil.)--Chinese University of Hong Kong, 2009.Includes bibliographical references (p. 86-88).Abstract also in Chinese.Table Of Contents --- p.iTables of Figures and Tables --- p.viChapter Chapter 1. --- Introduction --- p.1Chapter 1.1 --- Distribution Strategies --- p.1Chapter 1.2 --- Motivation --- p.7Chapter 1.3 --- Problem Description --- p.9Chapter 1.4 --- Contributions --- p.11Chapter 1.5 --- Conclusion --- p.12Chapter Chapter 2. --- Literature Review --- p.13Chapter 2.1 --- Crossdocking in the supply chain --- p.13Chapter 2.2 --- Simulation of crossdocking --- p.16Chapter 2.3 --- Mathematic programming in crossdocking --- p.17Chapter 2.4 --- Conclusion --- p.29Chapter Chapter 3. --- Model Approach and Assumptions --- p.30Chapter 3.1 --- Simulation Modeling --- p.30Chapter 3.2 --- Model Assumptions --- p.31Chapter 3.3 --- Crossdocking in Arena® -Modules --- p.36Chapter 3.4 --- Conclusion --- p.43Chapter Chapter 4. --- Simulation Design --- p.44Chapter 4.1 --- Factors in Simulation --- p.44Chapter 4.2 --- Experimental Design --- p.53Chapter 4.3 --- Performance Measures --- p.56Chapter 4.4 --- Conclusion --- p.57Chapter Chapter 5. --- Results and Analysis --- p.58Chapter 5.1 --- Mean Hourly Throughput per Forklift (MTF) --- p.58Chapter 5.2 --- Mean Handling Time per Pallet (MHP) --- p.63Chapter 5.3 --- Comparison with original results --- p.65Chapter 5.4 --- Conclusion --- p.68Chapter Chapter 6. --- Conclusion and Recommendations For Future Work --- p.82Chapter 6.1 --- Conclusion --- p.82Chapter 6.2 --- Future research directions --- p.84References --- p.8

SIMAID: a rapid development methodology for the design of acyclic, bufferless, multi-process and mixed model agile production facilities for spaceframe vehicles

The facility layout problem (FL) is a non-linear, NP-complete problem whose complexity is derived from the vast solution space generated by multiple variables and interdependent factors. For reconfigurable, agile facilities the problem is compounded by parallelism (simultaneity of operations) and scheduling issues. Previous work has either concentrated on conventional (linear or branched) facility layout design, or has not considered the issues of agile, reconfigurable facilities and scheduling. This work is the first comprehensive methodology incorporating the design and scheduling of parallel cellular facilities for the purpose of easy and rapid reconfiguration in the increasingly demanding world of agile manufacturing. A novel three-stage algorithm is described for the design of acyclic (asynchronous), bufferless, parallel, multi-process and mixed-model production facilities for spaceframe-based vehicles. Data input begins with vehicle part processing and volume requirements from multiple models and includes time, budget and space constraints. The algorithm consists of a powerful combination of a guided cell formation stage, iterative solution improvement searches and design stage scheduling. The improvement iterations utilise a modified (rules-based) Tabu search applied to a constant-flow group technology, while the design stage scheduling is done by the use of genetic algorithms. The objective-based solution optimisation direction is not random but guided, based on measurement criteria from simulation. The end product is the selection and graphic presentation of the best solution out of a database of feasible ones. The case is presented in the form of an executable program and three real world industrial examples are included. The results provide evidence that good solutions can be found to this new type and size of heavily constrained problem within a reasonable amount of time

Desenvolvimento de um sistema de apoio à decisão para problemas de empacotamento a três dimensões e com restrições adicionais

Tese de doutoramento, Estatística e Investigação Operacional (Análise de Sistemas), Universidade de Lisboa, Faculdade de Ciências, 2015Este trabalho aborda um problema real de empacotamento tridimensional enfrentado por uma empresa portuguesa. Diariamente, esta empresa necessita de organizar a arrumação de um conjunto de caixas numa viatura. A carga é composta por caixas paralelepipédicas de dimensões e pesos variados, e o veículo consiste num camião único, que terá de efectuar tantas viagens quantas as necessárias para entregar a totalidade da carga. Existem dois tipos de caixas de carga: caixas pequenas sem tampa que, antes de serem colocadas no camião, devem ser combinadas numa palete; caixas maiores totalmente formadas, que serão individualmente arrumadas no camião. O problema a resolver será dividido em duas fases sucessivas: a constituição de paletes com caixas pequenas e a arrumação da carga total (paletes e caixas individuais) no camião. Estas duas fases não deverão ser abordadas de forma independente, pois as dimensões finais das paletes construídas terão um impacto na composição do sortido de caixas de carga a arrumar no veículo. Para assegurar o regular transporte da carga teremos em atenção as seguintes restrições: estabilidade da carga durante o transporte, orientação das caixas, limite de peso do camião e distribuição do peso da carga. Para resolver este problema propomos uma heurística construtiva por camadas horizontais, com um critério de classificação de cantos livres, que coloca as caixas sempre junto a um canto livre. Para cada uma das camadas, a ideia base desta heurística consiste em espalhar as caixas mais pesadas, trabalhando desde as paredes do camião para o seu centro, favorecendo-se a obtenção de soluções admissíveis com uma boa distribuição do peso da carga. Para avaliar as soluções geradas pela nossa heurística, procedemos a testes computacionais com dados de benchmarking, comparando as nossas taxas de ocupação com os resultados de outros autores da literatura. Conduzimos, ainda, testes computacionais com dados reais da dita empresa.This work addresses a real world packing problem faced by a Portuguese company. Every day this company needs to establish a plan to pack a set of boxes onto a vehicle. The cargo consists of rectangular boxes with different sizes and weight, and the vehicle is a single truck. The truck will have to perform as many trips as necessary to deliver the entire load. There are two different types of boxes: small boxes with no lid that, before being placed inside the truck, need to be combined onto a pallet; bigger boxes, completely formed, that are packed individually in the truck. The problem can be divided into two successive phases: the construction of pallets with small boxes and the loading of the entire cargo (pallets and individual boxes) on the truck. These two phases should not be solved independently, since the final dimensions of the pallets will have an impact on the final packing plan of the whole cargo. To ensure a proper transportation, we will take into account the following constraints: load stability, box orientation, weight limit of the truck and distribution of weight inside the truck. To solve this problem, we propose a constructive heuristic based on a horizontal layer arrangement, with a criterion to classify the free corners, which places the boxes always next to a free corner. For each layer, the main idea is to spread the heaviest boxes along the truck, working from the sides to the centre of the truck, promoting the development of admissible solutions with a good weight distribution. To evaluate the solutions produced by our heuristic, we conduct computational tests with benchmarking data, comparing our occupancy rates with the results from other authors in the literature. We also undertake some computational experiments with real data from the company.Fundação para a Ciência e a Tecnologia (FCT), Programa de Apoio à Formação Avançada de Docentes do Ensino Superior Politécnico (PROTEC

Aggregate assembly process planning for concurrent engineering

In today's consumer and economic climate, manufacturers are finding it increasingly difficult to produce finished products with increased functionality whilst fulfilling the aesthetic requirements of the consumer. To remain competitive, manufacturers must always look for ways to meet the faster, better, and cheaper mantra of today's economy. The ability for any industry to mirror the ideal world, where the design, manufacturing, and assembly process of a product would be perfected before it is put mto production, will undoubtedly save a great deal of time and money. This thesis introduces the concept of aggregate assembly process planning for the conceptual stages of design, with the aim of providing the methodology behind such an environment. The methodology is based on an aggregate product model and a connectivity model. Together, they encompass all the requirements needed to fully describe a product in terms of its assembly processes, providing a suitable means for generating assembly sequences. Two general-purpose heuristics methods namely, simulated annealing and genetic algorithms are used for the optimisation of assembly sequences generated, and the loading of the optimal assembly sequences on to workstations, generating an optimal assembly process plan for any given product. The main novelty of this work is in the mapping of the optimisation methods to the issue of assembly sequence generation and line balancing. This includes the formulation of the objective functions for optimismg assembly sequences and resource loading. Also novel to this work is the derivation of standard part assembly methodologies, used to establish and estimate functional tunes for standard assembly operations. The method is demonstrated using CAPABLEAssembly; a suite of interlinked modules that generates a pool of optimised assembly process plans using the concepts above. A total of nine industrial products have been modelled, four of which are the conceptual product models. The process plans generated to date have been tested on industrial assembly lines and in some cases yield an increase in the production rate

Proceedings of the 2nd Conference on Production Systems and Logistics (CPSL 2021)

Proceedings of the CPSL 202

Optimization of Operation Sequencing in CAPP Using Hybrid Genetic Algorithm and Simulated Annealing Approach

In any CAPP system, one of the most important process planning functions is selection of the operations and corresponding machines in order to generate the optimal operation sequence. In this paper, the hybrid GA-SA algorithm is used to solve this combinatorial optimization NP (Non-deterministic Polynomial) problem. The network representation is adopted to describe operation and sequencing flexibility in process planning and the mathematical model for process planning is described with the objective of minimizing the production time. Experimental results show effectiveness of the hybrid algorithm that, in comparison with the GA and SA standalone algorithms, gives optimal operation sequence with lesser computational time and lesser number of iterations

Optimization of Operation Sequencing in CAPP Using Hybrid Genetic Algorithm and Simulated Annealing Approach

In any CAPP system, one of the most important process planning functions is selection of the operations and corresponding machines in order to generate the optimal operation sequence. In this paper, the hybrid GA-SA algorithm is used to solve this combinatorial optimization NP (Non-deterministic Polynomial) problem. The network representation is adopted to describe operation and sequencing flexibility in process planning and the mathematical model for process planning is described with the objective of minimizing the production time. Experimental results show effectiveness of the hybrid algorithm that, in comparison with the GA and SA standalone algorithms, gives optimal operation sequence with lesser computational time and lesser number of iterations

Autonomous Navigation of Automated Guided Vehicle Using Monocular Camera

This paper presents a hybrid control algorithm for Automated Guided Vehicle (AGV) consisting of two independent control loops: Position Based Control (PBC) for global navigation within manufacturing environment and Image Based Visual Servoing (IBVS) for fine motions needed for accurate steering towards loading/unloading point. The proposed hybrid control separates the initial transportation task into global navigation towards the goal point, and fine motion from the goal point to the loading/unloading point. In this manner, the need for artificial landmarks or accurate map of the environment is bypassed. Initial experimental results show the usefulness of the proposed approach.COBISS.SR-ID 27383808