Overview on: sequencing in mixed model flowshop production line with static and dynamic context

In the present work a literature overview was given on solution techniques considering basic as well as more advanced and consequently more complex arrangements of mixed model flowshops. We first analyzed the occurrence of setup time/cost; existing solution techniques are mainly focused on permutation sequences. Thereafter we discussed objectives resulting in the introduction of variety of methods allowing resequencing of jobs within the line. The possibility of resequencing within the line ranges from 1) offline or intermittent buffers, 2) parallel stations, namely flexible, hybrid or compound flowshops, 3) merging and splitting of parallel lines, 4) re-entrant flowshops, to 5) change job attributes without physically interchanging the position. In continuation the differences in the consideration of static and dynamic demand was studied. Also intermittent setups are possible, depending on the horizon and including the possibility of resequencing, four problem cases were highlighted: static, semi dynamic, nearly dynamic and dynamic case. Finally a general overview was given on existing solution methods, including exact and approximation methods. The approximation methods are furthermore divided in two cases, know as heuristics and methaheuristic

Joint cell loading and scheduling approach to cellular manufacturing systems

Cataloged from PDF version of article.A hierarchical multi-objective heuristic algorithm and pricing mechanism are developed to first determine the cell loading decisions, and then lot sizes for each item and to obtain a sequence of items comprising the group technology families to be processed at each manufacturing cell that minimise the setup, inventory holding, overtime and tardiness costs simultaneously. The linkage between the different levels is achieved using the proposed pricing mechanism through a set of dual variables associated with the resource and inventory balance constraints, and the feasibility status feedback information is passed between the levels to ensure internally consistent decisions. The computational results indicate that the proposed algorithm is very efficient in finding a compromise solution for a set of randomly generated problems compared with a set of competing algorithms. © 2011 Taylor & Francis

Quality Driven Scheduling in Construction

Despite the enormous research effort that has been made in the last fifty years, the goal of construction scheduling quality seems still a long way far. This dissertation has the aim of contributing to the understanding of the quality of construction scheduling, and three issues have been chosen: schedule quality; quality and project control; scheduling approaches for construction. The goal of the whole research work is to study quality in scheduling and project controlling, and to propose some possible research lines to better understand the needed quality for the planning, scheduling, and controlling approaches in construction projects, i.e. quality driven scheduling.Starting from the development of the Critical Path Method (CPM), PERT and Precedence Diagramming, until the recent Location-Based Planning, project scheduling has been developing and improving continuously. However, construction project scheduling systems are still considered to miss the goal of increasing project control efficiency. Project Scheduling is, indeed, one of the basic tools of construction project management, and the success of a project partially depends on having a high quality schedule that defines when each activity will occur and with which duration, and its logic links with other activities and their sequences. Moreover, construction productivity is considered to be improved through scheduling as it can manage different problems such as process productivity, coordination and safety, and connections between systems and processes. Quality of construction scheduling has been object of research in a rather limited manner, and the need of recommended schedule development practices for quality assurance of scheduling processes and deliverables still exists. Therefore, the research work is based upon three main research questions: a) what is schedule quality? b) what does scheduling produce in terms of quality? c) can the activity network schedule model be process-oriented and quality driven? The gained results propose the following regarding to the research questions.a) What is schedule quality? Schedule quality is the fulfilment of many schedule requirements, with the aim of satisfying the needs of work structuring of construction process and of scheduling mechanics. A method of understanding and measuring schedule quality in construction, termed “Schedule Health Assessment” is proposed. The Schedule Health Assessment method also has the aim of guiding the project scheduler in the schedule development process.b) What does scheduling produce in terms of quality? Project schedule is the basis for project control, mostly addressing time and progress of activities, and costs, while quality control is usually separated. Although, these three project objectives are interdependent, and process and product quality management should be fully included in project control. Quality control should be integrated in the project schedule through a “Quality Breakdown Structure”.c) Can the activity network schedule model be process-oriented and quality driven? Activity network creates logic of work structuring. A process-oriented scheduling method for construction has to deal with resources, workflow and spaces. The proposed method, termed Repetitive Networking Technique (REPNET), creates a quality driven construction-oriented schedule model by plotting network logic on resource-space charts and on flowlines.The research results suggest the implementation of these three approaches in the project scheduling of a construction project can improve the quality driven scheduling of the project, meaning the implementation of a good quality schedule, the integration in project control processes of the delivered quality and the process-oriented scheduling

Dynamic set-up rules for hybrid flow shop scheduling with parallel batching machines

An S-stage hybrid (or flexible) flow shop, with sequence-independent uniform set-up times, parallel batching machines with compatible parallel batch families (like in casting or heat treatments in furnaces, chemical or galvanic baths, painting in autoclave, etc.) has been analysed with the purpose of reducing the number of tardy jobs (and the makespan); in Graham’s notation: FPB(m_1, m_2, … , m_S)|p-batch, STsi,b|SUM(Ui). Jobs are sorted dynamically (at each new delivery); batches are closed within sliding (or rolling) time windows and processed in parallel by multiple identical machines. Computation experiments have shown the better performance on benchmarks of the two proposed heuristics based on new formulations of the critical ratio (CRsetup) considering the ratio of allowance set-up and processing time in the scheduling horizon, which improves the weighted modified operation due date rule

Interaction of design and operational parameters in periodic review kanban systems

In this study, we propose an analytical model to determine the withdrawal cycle length, kanban sizes and number of kanbans simultaneously in a multi-item, multi-stage, multi-period, capacitated periodic review kanban system. Traditionally, research in kanban systems has been separated into 'design level' research, and 'shop floor level' research. In both veins of research, especially for the design level, various algorithms have been developed. However, it is important to state that there is a significant relationship between the design parameters and the operational issues, such as kanban schedules and actual lead times. Therefore, we analytically consider the interdependencies between the design and operational decisions, and evaluate their impact on each other

Analyzing longitudinal patterns of river metabolism in five distinct rivers

2021 Summer.Includes bibliographical references.The River Continuum and Serial Discontinuity Concepts are two common frameworks or theories to describe river ecosystem structure and function. While these concepts help explain how rivers should behave, the reality is that aquatic ecosystems are being changed and degraded due to dams which regulate flow and changes to land use and land cover that can negatively impact aquatic ecosystems. Ecosystem metabolism is an increasingly common way to monitor and assess river health and functioning. This analysis is a data synthesis to examine longitudinal coherence in productivity patterns and identify the strongest controls that disrupt coherence. I find that between discharge, dissolved oxygen, and metabolism, metabolism is the least predictable variable going downstream regardless of land use and river characteristics, but at the same time did show patterns consistent with the expected patterns of the River Continuum Concept or other theories of river function variation. This lack of coherence and predictability in river metabolism across sites within rivers highlights effects monitoring methods, river-specific characteristics, and the overall lack of satisfactory theories for how larger rivers behave, despite an abundance of riverine theories

Artificial Intelligence as an Enabler of Quick and Effective Production Repurposing Manufactur-ing: An Exploratory Review and Future Research Propositions

The outbreak of Covid-19 created disruptions in manufacturing operations. One of the most serious negative impacts is the shortage of critical medical supplies. Manufacturing firms faced pressure from governments to use their manufacturing capacity to repurpose their production for meeting the critical demand for necessary products. For this purpose, recent advancements in technology and artificial intelligence (AI) could act as response solutions to conquer the threats linked with repurposing manufacturing (RM). The study’s purpose is to investigate the significance of AI in RM through a systematic literature review (SLR). This study gathered around 453 articles from the SCOPUS database in the selected research field. Structural Topic Modeling (STM) was utilized to generate emerging research themes from the selected documents on AI in RM. In addition, to study the research trends in the field of AI in RM, a bibliometric analysis was undertaken using the R-package. The findings of the study showed that there is a vast scope for research in this area as the yearly global production of articles in this field is limited. However, it is an evolving field and many research collaborations were identified. The study proposes a comprehensive research framework and propositions for future research development

Design and scheduling of periodic review kanban systems

Ankara : Department of Industrial Engineering and Institute of Engineering and Sciences, Bilkent Univ., 1997.Thesis (Master's) -- Bilkent University, 1997.Includes bibliographical references leaves 107-112In the last years, the term just in-time (JIT) has become a common term in repretitive manufacturing systems. It can be defined as the ideal of having the necessary amount of material available where it is needed and when it is needed. One of the major elements of JIT philosophy and pull mechanism is the Kanban system. This system is the information processing and hence shop floor control system of JIT philosophy. In this study, we propose an algorithm to determine the withdrawal cycle length, kanban size and number of kanbans simultancously in a periodic review Kanban system under multi-item, multi-stage, multi period modified flowline production setting. The proposed algorithm considers the impact of operating characteristics such a.s scheduling and actual lead times on design parameters.Erhun, FeryalM.S