Balancing labor requirements in a manufacturing environment

“This research examines construction environments within manufacturing facilities, specifically semiconductor manufacturing facilities, and develops a new optimization method that is scalable for large construction projects with multiple execution modes and resource constraints. The model is developed to represent real-world conditions in which project activities do not have a fixed, prespecified duration but rather a total amount of work that is directly impacted by the level of resources assigned. To expand on the concept of resource driven project durations, this research aims to mimic manufacturing construction environments by allowing a non-continuous resource allocation to project tasks. This concept allows for resources to shift between projects in order to achieve the optimal result for the project manager. Our model generates a novel multi-objective resource constrained project scheduling problem. Specifically, two objectives are studied; the minimization of the total direct labor cost and the minimization of the resource leveling. This research will utilize multiple techniques to achieve resource leveling and discuss the advantage each one provides to the project team, as well as a comparison of the Pareto Fronts between the given resource leveling and cost minimization objective functions. Finally, a heuristic is developed utilizing partial linear relaxation to scale the optimization model for large scale projects. The computation results from multiple randomly generated case studies show that the new heuristic method is capable of generating high quality solutions at significantly less computational time”--Abstract, page iv

Planning and scheduling in the digital factory

Production planning and scheduling with the aid of software tools in today’s manufacturing industries have become a common practice which is indispensable for providing high level customer service, and at the same time to utilize the production resources, like workforce, machine tools, raw materials, energy, etc., efficiently. To meet the new requirements, problem modeling tools, optimization techniques, and visualization of data and results have become part of the software packages. In this chapter some recent developments in problem modeling and optimization techniques applied to important and challenging industrial planning and scheduling problems are presented. We will focus on new problem areas which are still at the edge of current theoretical research, but they are motivated by practical needs. On the one hand, we will discuss project based production planning, and on the other hand, we will tackle a resource leveling problems in a machine environment. We will present the problems, some modeling and solution approaches, and various extensions and applications

A Decision Support System for Dynamic Integrated Project Scheduling and Equipment Operation Planning

Common practice in scheduling under limited resource availability is to first schedule activities with the assumption of unlimited resources, and then assign required resources to activities until available resources are exhausted. The process of matching a feasible resource plan with a feasible schedule is called resource allocation. Then, to avoid sharp fluctuations in the resource profile, further adjustments are applied to both schedule and resource allocation plan within the limits of feasibility constraints. This process is referred to as resource leveling in the literature. Combination of these three stages constitutes the standard approach of top-down scheduling. In contrast, when scarce and/or expensive resource is to be scheduled, first a feasible and economical resource usage plan is established and then activities are scheduled accordingly. This practice is referred to as bottom-up scheduling in the literature. Several algorithms are developed and implemented in various commercial scheduling software packages to schedule based on either of these approaches. However, in reality resource loaded scheduling problems are somewhere in between these two ends of the spectrum. Additionally, application of either of these conventional approaches results in just a feasible resource loaded schedule which is not necessarily the cost optimal solution. In order to find the cost optimal solution, activity scheduling and resource allocation problems should be considered jointly. In other words, these two individual problems should be formulated and solved as an integrated optimization problem. In this research, a novel integrated optimization model is proposed for solving the resource loaded scheduling problems with concentration on construction heavy equipment being the targeted resource type. Assumptions regarding this particular type of resource along with other practical assumptions are provided for the model through inputs and constraints. The objective function is to minimize the fraction of the execution cost of resource loaded schedule which varies based on the selected solution and thus, considered to be the model's decision making criterion. This fraction of cost which hereafter is referred to as operation cost, encompasses four components namely schedule delay cost, shipping, rental and ownership costs for equipment

Scheduling Elective Surgeries in Operation Room with Optimization of Post-Surgery Recovery Unit Capacity

Scheduling of surgeries in the Operation rooms with limited available resources is a very complex process. Patients of different specialties are operated by surgery teams in operation rooms and sent to recovery units. In this thesis, we develop a model to help Operation room scheduling management to schedule elective patients based on the availability of surgeons and operation rooms with three phase hierarchical approach of scheduling. A linear integer goal programming method is used to solve problem. The model tries to minimize number of patients waiting for service, underutilization of operating room hours and maximum number of patients in the recovery units. Windsor Regional Hospital help is taken to understand the surgery booking procedure. Lexicographic goal programming method and weighted goal programming is employed and various combinations of priorities are solved to schedule Operating rooms. The focus of the study is to develop mathematical model for scheduling

Non-linear time-cost trade-off models of activity crashing: Application to construction scheduling and project compression with fast-tracking

When shortening a project’s duration, activity crashing, fast-tracking and substitution are the three most commonly employed compression techniques. Crashing generally involves allocating extra resources to an activity with the intention of reducing its duration. To date, the activity time-cost relationship has for the most part been assumed to be linear, however, a few studies have suggested that this is not necessarily the case in practice. This paper proposes two non-linear theoretical models which assume either collaborative or non-collaborative resources. These models closely depict the two most common situations occurring during construction projects. The advantages of these models are that they allow for both discrete and continuous, as well as deterministic and stochastic configurations. Additionally, the quantity of resources required for crashing the activity can be quantified. Comparisons between the models and another recent fast-tracking model from the literature are discussed, and a Genetic Algorithm is implemented for a fictitious application example involving both compression techniques

Non-linear time-cost trade-off models of activity crashing: Application to construction scheduling and project compression with fast-tracking

[EN] When shortening a project's duration, activity crashing, fast-tracking and substitution are the three most commonly employed compression techniques. Crashing generally involves allocating extra resources to an activity with the intention of reducing its duration. To date, the activity time-cost relationship has for the most part been assumed to be linear, however, a few studies have suggested that this is not necessarily the case in practice. This paper proposes two non-linear theoretical models which assume either collaborative or non-collaborative resources. These models closely depict the two most common situations occurring during construction projects. The advantages of these models are that they allow for both discrete and continuous, as well as deterministic and stochastic configurations. Additionally, the quantity of resources required for crashing the activity can be quantified. Comparisons between the models and another recent fast-tracking model from the literature are discussed, and a Genetic Algorithm is implemented for a fictitious application example involving both compression techniques.This research was supported by the CIOB Bowen Jenkins Legacy Research Fund (reference BLJ2016/BJL.01) and by NERC under the Environmental Risks to Infrastructure Innovation Programme (reference NE/R008876/1) at the University of Reading.Ballesteros-Pérez, P.; Elamrousy, KM.; González-Cruz, M. (2019). Non-linear time-cost trade-off models of activity crashing: Application to construction scheduling and project compression with fast-tracking. Automation in Construction. 97:229-240. https://doi.org/10.1016/j.autcon.2018.11.0012292409

Exact and Heuristic Methodologies for Scheduling in Hospitals: Problems, Formulations and Algorithms..

Dit proefschrift handelt over een aantal exacte en heuristische pro cedures voor planningsproblemen die opduiken binnen ziekenhuizen. H et materiaal kan opgedeeld worden in drie delen. Het eerste deel richt z ich op personeelsplanning. We introduceren een nieuwe formulering en ont ledingsbenadering voor een probleem dat het opstellen van een assistente nplanning op lange termijn behelst. De benadering ontleedt het probleem op basis van de activiteiten en maakt gebruik van kolomgeneratie om een optimale oplossing te bekomen. Het resulterende vertak-en-prijs algoritm e werd geïmplementeerd in een applicatie, aangevuld met heuristische zoe kprocedures en getest op een aantal praktijkproblemen. Onze experimentel e resultaten tonen een belangrijke toename in efficiëntie aan, vergeleke n met de traditionele benaderingen die het probleem ontleden op basis va n de stafleden. Het tweede deel van deze thesis handelt over het plannen van het operati ekwartier. Eerst stellen we een model en computerprogramma voor om het g ebruik van diverse hulpmiddelen in functie van de cyclische hoofdplannin g van het operatiekwartier te visualiseren. Vervolgens stellen we een aa ntal modellen en algoritmes voor om planningen te genereren met een afge vlakte, resulterende bedbezetting. Onze ideeën werden getest op praktijk data in twee gevalstudies. In het derde deel combineren we de kennis verkregen uit de eerste twee d elen in een geïntegreerd model voor de planning van het personeel en het operatiekwartier. Het model wordt opgelost door een vertak-en-prijs alg oritme dat herhaaldelijk twee verschillende subproblemen oplost. Het eer ste behelst het genereren van een individuele planning van een personeel slid d.m.v. dynamische programmering. In het tweede subprobleem zoeken w e naar een planning van het operatiekwartier met een bijhorende ben odigde personeelsbezetting die goed past bij de gegenereerde set va n individuele planningen. Dit gebeurt via het oplossen van een geheeltal lig programmeringsprobleem. We hebben mooie rekenresultaten bekomen voor dit moeilijke probleem. Tenslotte wordt er aangetoond hoe onze benaderi ng gebruikt kan worden om verschillende ziekenhuizen te vergelijken. Con creet illustreren we hoe de resultaten geïnterpreteerd kunnen worden om de bronnen van verspilling in het personeelsbeleid van een ziekenhuis te detecteren.