1,169 research outputs found
Two-dimensional placement compaction using an evolutionary approach: a study
The placement problem of two-dimensional objects over planar surfaces optimizing
given utility functions is a combinatorial optimization problem. Our main drive is that of
surveying genetic algorithms and hybrid metaheuristics in terms of final positioning area
compaction of the solution. Furthermore, a new hybrid evolutionary approach, combining
a genetic algorithm merged with a non-linear compaction method is introduced and
compared with referenced literature heuristics using both randomly generated instances
and benchmark problems. A wide variety of experiments is made, and the respective
results and discussions are presented. Finally, conclusions are drawn, and future research
is defined
Meta-heuristic Algorithms for Nesting Problem of Rectangular Pieces
Nesting problems consist of placing multiple items onto larger shapes finding a good arrangement. The goal of the nesting process is to minimize the waste of material. It is common to assume, as in the present work, that the stock sheet has fixed width and infinite height, since in the real world a company may have to cut pieces from a roll of material. The complexity of such problems is often faced with a two-stage approach, so-called \u201chybrid algorithm\u201d, combining a placement routine and a meta-heuristic algorithm. Starting from a given positioning sequence, the placement routine generates a non-overlapping configuration. The encoded solution is manipulated and modified by the meta-heuristic algorithm to generate a new sequence that brings to a better value of the objective function (in this case the height of the strip). The proposed method consists in placing the rectangles inside a strip and in combining the meta-heuristic algorithms with the No Fit Polygon algorithm. The software has been developed in Python language using proper libraries to solve the meta-heuristic techniques (Inspyred) and the geometric problems (Polygon). The results show the effectiveness of the proposed method; moreover, with regard to problems reported in literature employed as benchmark of the nesting algorithms, the degree of occupation values (Efficiency Ratio, ER) are shown to be higher than 90%
A two-stage packing procedure for a Portuguese trading company
This case study deals with a two-stage packing problem that has to be solved in the
daily distribution process of a Portuguese trading company. At the first stage boxes
including goods are to be packed on pallets while at the second stage these pallets are
loaded into one or more trucks. The boxes have to be transported to different customers
and the actual goal is to guarantee a sufficient utilization of the truck loading spaces. A
two-stage packing procedure is proposed to cover both problem stages. First boxes are
loaded onto pallets using a well-known container loading algorithm. Then trucks are
filled with loaded pallets by means of a new tree search algorithm. The applicability and
performance of the two-stage approach was evaluated with a set of instances that are
based on actual company data
Аналіз генетичних алгоритмів розв’язання задачі двовимірної ортогональної упаковки прямокутних об’єктів у напівнескінченну смугу
Досліджено клас генетичних алгоритмів вирішення задачі двовимірної ортогональної упаковки прямокутних об’єктів у напівнескінченну смугу фіксованої ширини. Наведено результати теоретичного аналізу складності реалізації декодерів MERA та BLF; запропоновані власні реалізації цих декодерів з низкою евристичних оптимізацій. Запропоновано реалізацію генетичного алгоритму розв’язання задачі упаковки для окремих випадків (із забороною поворотів об’єктів та з поворотами на 90 °). Описано результати тестових випробувань розробленого алгоритму за різних конфігурацій основних параметрів з використанням загальновідомих тестових наборів. Наведено результати порівняння отриманого алгоритму з іншими відомими алгоритмами.Исследован класс генетических алгоритмов решения задачи двухмерной ортогональной упаковки прямоугольных объектов в полубесконечную полосу фиксированной ширины. Приведены результаты теоретического анализа сложности реализации декодеров MERA и BLF; предложены собственные реализации этих декодеров с рядом эвристических оптимизаций. Предложена реализация генетического алгоритма решения задачи упаковки для отдельных случаев (с запретом поворотов объектов и с поворотами на 90°). Описаны результаты тестирования разработанного алгоритма при разных конфигурациях основных параметров с использованием общеизвестных тестовых наборов. Приведены результаты сравнения полученного алгоритма с другими известными алгоритмами.A class of genetic algorithms for solving the 2D Strip Packing Problem is investigated. The theoretical analysis of the complexity of implementing decoders MERA and BLF is done. Original implementations of these MERA and BLF decoders enhanced with a number of heuristic optimizations are proposed. Genetic algorithm for solving the 2D Strip Packing Problem for special cases (allowed/forbidden objects rotation by 90°) with the use of MERA/BLF decoders is proposed. Extensive computational experiments with well-known instances are performed to analyze different configurations of basic parameters of proposed genetic algorithm. The comparison of the obtained algorithm with other known algorithms is given
Methodology to Solve Multi-Dimentional Sphere Packing Problems
This paper discusses the problem of optimally packing spheres of various dimensions into containers of arbitrary geometrical shapes. According to the international classification, this problem belongs to Sphere Packing Problems (SPPs). The aim of this work is to create an integrated methodology for solving SPPs.В статті розглядається задача оптимального розміщення куль різної розмірності в контейнерах довільних геометричних форм. Згідно з міжнародною класифікацією ця задача належить до класу SPP (Sphere Packing Problems). Метою даної роботи є створення єдиної методології розв’язання задач SPP.В статье рассматривается задача оптимального размещения шаров различной размерности в контейнерах произвольных геометрических форм. Согласно международной классификации эта задача относится к классу SPP (Sphere Packing Problems). Целью данной работы является создание единой методологии решения задач SPP
Training software for orthogonal packing problems
An open source architecture for the interactive solution of packing problems in two dimensions is presented. Although primarily developed for helping engineering students to understand the algorithmic approaches to the solution of difficult combinatorial optimization problems, the application can be useful to practitioners and developers thanks to its visual tools. The paper gives intuitive and formal definitions of the problems at hand, discusses two natural heuristic approaches, provides technical information on the application, and reports the results of classroom experimental testings
Container Loading Problems: A State-of-the-Art Review
Container loading is a pivotal function for operating supply chains efficiently. Underperformance results in unnecessary costs (e.g. cost of additional containers to be shipped) and in an unsatisfactory customer service (e.g. violation of deadlines agreed to or set by clients). Thus, it is not surprising that container loading problems have been dealt with frequently in the operations research literature. It has been claimed though that the proposed approaches are of limited practical value since they do not pay enough attention to constraints encountered in practice.In this paper, a review of the state-of-the-art in the field of container loading will be given. We will identify factors which - from a practical point of view - need to be considered when dealing with container loading problems and we will analyze whether and how these factors are represented in methods for the solution of such problems. Modeling approaches, as well as exact and heuristic algorithms will be reviewed. This will allow for assessing the practical relevance of the research which has been carried out in the field. We will also mention several issues which have not been dealt with satisfactorily so far and give an outlook on future research opportunities
- …