1,720,967 research outputs found
A flexible operating tool to provide an efficient project's staffing and resource allocation
No full textA Biased-Randomized Discrete Event Algorithm to Improve the Productivity of Automated Storage and Retrieval Systems in the Steel Industry
Full text linkIn automated storage and retrieval systems (AS/RSs), the utilization of intelligent algorithms can reduce the makespan required to complete a series of input/output operations. This paper introduces a simulation optimization algorithm designed to minimize the makespan in a realistic AS/RS commonly found in the steel sector. This system includes weight and quality constraints for the selected items. Our hybrid approach combines discrete event simulation with biased-randomized heuristics. This combination enables us to efficiently address the complex time dependencies inherent in such dynamic scenarios. Simultaneously, it allows for intelligent decision making, resulting in feasible and high-quality solutions within seconds. A series of computational experiments illustrates the potential of our approach, which surpasses an alternative method based on traditional simulated annealing
A multistart biased-randomized algorithm for solving a three-dimensional case picking problem with real-life constraints
No full textThis paper introduces the three-dimensional case picking problem (3D-CPP) and proposes a multistart biased-randomized algorithm (BRA) to solve it. The 3D-CPP combines two important topics in modern warehouse logistics: the pallet loading problem and the routing of pickers in manual warehouses. The proposed optimization procedure aims at minimizing the overall distance traveled by the pickers, and is achieved by combining a routing problem (i.e., the order in which picking positions are visited) with a loading problem (i.e., the way in which cases are placed onto the pallet). We also consider additional constraints regarding the weight, vertical support, and strength of the cases. In order to solve this problem, we first propose a constructive heuristic which combines routing and packing procedures. This initial heuristic is then extended into a multistart BRA by employing a skewed probability distribution to introduce a certain degree of randomness during the solution-construction process. A series of computational experiments allow us to assess the quality of the proposed approach, through a comparison with other algorithms as well as using real-life data provided by an industrial partner
Optimizing Retrieving Performance of an Automated Warehouse for Unconventional Stock Keeping Units
Full text linkIn recent years, the diffusion of automated warehouses in different industrial sectors has fostered the design of more complex automated storages and handling solutions. These circumstances, from a technological point of view, have led to the development of automated warehouses that are very different from the classic pallet Automated Storage and Retrieval Systems (AS/RS), both in terms of design and operating logic. A context in which these solutions have spread is the steel sector. Warehouses with innovative layouts and operating logics have been designed to move metal bundles of different sizes, weights and quality levels, instead of standard, interchangeable stock keeping units. Moreover, picking is often not allowed in these warehouses, due to the configuration of the loading units. In this work we propose a meta-heuristic algorithm based on the Simulated Annealing (SA) procedure, which aims to optimize performance during the retrieving phase of an automated warehouse for metal bundles. The algorithm translates the customers’ requests, expressed in terms of item code, quality and weight into a list of jobs. The goal is to optimize the retrieving performance, measured in missions per hour, minimizing the deviations in quality and weight between customer request and the material retrieved. For the validation, a simulation model of an existing warehouse has been created and the performance of the algorithm tested on the simulation model has been compared with the current performance of the warehouse
Maturity Models in Industrial Internet: a Review
Full text linkThe introduction of assembly lines in industrial plants marked the beginning of the third industrial revolution. The support of information technology has enabled continuous progresses, up to the digitalisation of the processes. In this context, the further innovation characterised by the introduction of Cyber-Physical Systems and other enabling technologies has allowed the fourth industrial revolution. Proposed by the German government, Industry 4.0 appealed to both researchers and practitioners. Since the appearance of the term Industry 4.0, the linked-term Industrial Internet has been introduced to indicate the technology stack and knowledge management required by Industry 4.0. Industrial Internet makes a factory smart by applying advanced information and communication systems and future-oriented technologies, as well as new principles of knowledge management. Undeniably, such a system introduces greater complexity in terms of technologies, knowledge and socio-cultural aspects. Companies are often unprepared to deal with innovation issues, because they lack knowledge and competences and they are not culturally prepared for the relative novelties, but especially because they lack the necessary technological pre-requisites to develop the appropriate technology stack. From this perspective, different models of maturity have been developed, both in academic and technical environments, to support companies in understanding their position within the paradigm of the Industrial Internet. Starting from a quantitative review of the maturity models designed in the general literature, this article develops a qualitative review of the models applied in Industry 4.0, characterising all relevant models and proposing future perspectives to improve existing models and develop new ones
A new heuristic algorithm to improve the design of a vertical storage system
Full text linkIn this paper, a new heuristic algorithm to support the design phase of a vertical storage system is presented. The considered vertical storage system is made up of racks accommodating metal containers which are arranged on the two sides of the lift device that feeds them. The proposed heuristic algorithm has been developed combining two well-known problems: Bins Packing Problem (BPP) and Rectangular Nesting Problem (RNP). Given a list of products that must be stored, the dimensions of the warehouse's racks and its load capacity, the developed algorithm allows to obtain the list of products that must be placed in each stock keeping unit and returns the right position and orientation any item should take. The algorithm provides the minimum number of racks with height dimension as low as possible. This aim is due to the common interest of automated vertical storage systems designers or owners in lowering costs, which trend to grow up with racks number and height. Furthermore, the position of the items inside each rack is managed to optimize the volume exploitation and to balance the container distributing the weight inside it. The whole procedure also regards the maximum weight constrain that basically limits the filling of loading units. The robustness of the proposed algorithm has been studied simulating different scenarios, by changing boundary conditions such as the number of items to be stored, their middleweight, their average size and the variance of these physical characteristics. Finally, the algorithm has been applied in a realistic situation to support automated vertical storage system design aimed at holding in stock metal moulds
Project Time Deployment: a new lean tool for losses analysis in Engineer-to-Order production environments
No full textThis paper presents a novel lean tool called Project Time Deployment (PTD) whose objectives are to classify, analyse, and eliminate losses in order to reduce production lead time in Engineer-to-Order (ETO) environments. By combining two already known approaches, i.e. the Manufacturing Critical-path Time and the Manufacturing Cost Deployment, PTD identifies the critical losses affecting the project, focusing on the business processes where causal losses occur, and providing opportunities for greater efficiency and effectiveness by reducing or even eliminating them. In ETO projects, the lead time and respecting deadlines are of paramount importance and they are often threatened by several different losses that are difficult to compare. Companies thus need a tool to identify the losses and the tasks where they occur, quantifying them in terms of a single dimension: the time. PTD was designed using a methodology based on four steps: analysis of current solutions, concept design and prototype, proof of concept and validation, and definition of future researches. It was also validated in an industrial implementation concerning an Engineering, Procurement & Construction company operating in the steel industry, and led to an approximate 24% reduction in lead time
Going Beyond Counting First Authors in Author Co-citation Analysis
Full text linkThe present study examines one of the fundamental aspects of author co-citation analysis (ACA) - the way co-citation
counts are defined. Co-citation counting provides the data on which all subsequent statistical analyses and mappings
are based, and we compare ACA results based on two different types of co-citation counting - the traditional type that
only counts the first one among a cited work's authors on the one hand and a non-traditional type that takes into
account the first 5 authors of a cited work on the other hand. Results indicate that the picture produced through this non-traditional author co-citation counting contains more coherent author groups and is therefore considerably clearer. However, this picture represents fewer specialties in the research field being studied than that produced through the traditional first-author co-citation counting when the same number of top-ranked authors is selected and analyzed. Reasons for these effects are discussed
Variations on the Author
Full text link“Variations on the Author” discusses two of Eduardo Coutinho’s recent films (Um Dia na Vida, from 2010, and Últimas Conversas, posthumously released in 2015) and their contribution to the general question of documentary authorship. The director’s filmography is characterized by a consistent yet self-effacing form of authorial self-inscription: Coutinho often features as an interviewer that rather than express opinions propels discourses; an interviewer that is good at listening. This mode of self-inscription characterizes him as an author who is not expressive but who is nonetheless markedly present on the screen. In Um Dia na Vida, however, Coutinho is completely absent form the image, while Últimas Conversas, on the contrary, includes a confessional prologue that moves the director from the margins to the center of his films. This article examines the ways in which these works stand out in the filmography of a director who offers new insights into the notion of cinematic authorship
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