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  • About
  • The Global ETD Search service is a free service for researchers to find electronic theses and dissertations. This service is provided by the Networked Digital Library of Theses and Dissertations.
    Our metadata is collected from universities around the world. If you manage a university/consortium/country archive and want to be added, details can be found on the NDLTD website.
1

A multiple ant colony metaheuristic for the air refueling tanker assignment problem

Annaballi, RonJon. January 2002 (has links)
Thesis (M.S.)--Air Force Institute of Technology, 2002. / Title from title screen (viewed Oct. 28, 2003). Vita. "AFIT/GOR/ENS/02-01." Includes bibliographical references (leaves 84-86). Also issued in paper format.
2

Heuristic scheduling of low acuity patients at the emergency department

Khadndekar, Shashank. January 2007 (has links)
Thesis (M.S.)--State University of New York at Binghamton, Department of Systems Science and Industrial Engineering, 2007. / Includes bibliographical references (leaves 121-125).
3

Parallel machine scheduling with time windows

Rojanasoonthon, Siwate. Bard, Jonathan F. January 2004 (has links) (PDF)
Thesis (Ph. D.)--University of Texas at Austin, 2004. / Supervisor: Jonathan F. Bard. Vita. Includes bibliographical references.
4

An heuristic approach for the improvement of aircraft departure scheduling at airports

Teixeira, Roberto de Barros January 1992 (has links)
This work considers the management in the short run of aircraft departures from their parking stands at major airports where traffic congestion is noticeable. At the ground level, congestion is patent when carefully designed departure time tables become unworkable, causing ever increasing delays which penalize heavily passengers, airlines and the airport surrounding community. The study is composed of two parts: First an overall analysis of the considered problem is performed to provide background knowledge and to display basic principles for the management of aircraft ground movements at modem airports. Physical components as well as current operational rules are discussed and their interdependence is revealed. A particular importance is given to new and foreseeable developments in communication and guidance technology which allow an improved prediction of runway occupancy times or gaps. Capacity issues are also discussed with respect to aircraft ground activities and the airfield capacity is analysed. This first part of the work ends with the description of levels of fuel consumption and of pollution emission by aircraft ground operations and thus shows the relevance of the problem considered in this study. The second part of this work is devoted to the design of a just-in-time clearance policy which should minimise environment, fuel and pollution levels and made possible a delay-free ground traffic for departing aircraft A mathematical formulation of the considered decision problem, characterized as a real time scheduling problem, is built up. Then possible solution strategies are appraised and an "ad hoc" heuristic solution algorithm is designed. This solution is first compared in theoretical terms with a First Come First Served policy showing that in an error-free situation the proposed solution cannot be worse than its competitor. Then a simulation study is performed which confirms in practical terms the above result The influence of the main design parameters of the solution algorithm on its performance are also examined giving some insights in relation to necessary communication and prediction aids. Finally, possible extensions of the proposed method and its integration in a global aircraft traffic management system are discussed.
5

Scheduling the hybrid flowshop : branch and bounnd algorithms

Moursli, Omar 12 February 1999 (has links)
This thesis studies Production Scheduling in a multistage hybrid flowshop facility. It first states the general Production Planning and Scheduling problem and highlights some drawbacks of classical solutions. A theoretical decomposition-based approach is introduced whose main issue is to overcome non-efficient capacity utilization. By using Branch and Bound methods, an in-depth analysis of the scheduling part of the system is then carried out throughout the study and development of upper and lower bounds as well as branching schemes. Already-existing and new heuristics are presented and compared on different shop floor configurations. Five different heuristic approaches are studied. By scheduling the HFS one stage at a time the first approach uses different stage sequencing orders. The second and third approaches are mainly list heuristics. The second approach uses ideas derived from the multistage classical flowshop with a single machine per stage, while the third approach uses classical dispatching priority rules. The fourth and fifth approaches, respectively, use random scheduling and local search techniques. Statistical analysis is carried out in order to compare the heuristics and to select the best of them for each shop configuration. Already-existing and new lower bounds on the single stage subproblem are also presented and compared. Three new lower bounds are developed: a dual heuristic based bound, a partially preemptive bound and a heuristic for the so-called subset bound. Some of these lower bounds use a network flow algorithm. A new version of the “Preflow Push” algorithm which runs faster than the original one is presented. The best lower bounds are selected based on numerical tests. Two branch and bound algorithms are presented, an improved version of the sequence enumeration method and a generalization of the so-called interval branching method, along with several bounding strategies. Based on the upper and lower bound studies, several branch and bound algorithms are presented and compared using numerical tests on different shop floor configurations. Eventually, an Object Model for Scheduling Algorithm Implementations (OMSAI), that has been used for the computer implementation of the developed algorithms, is presented.
6

Scheduling the hybrid flowshop : branch and bounnd algorithms

Moursli, Omar 12 February 1999 (has links)
This thesis studies Production Scheduling in a multistage hybrid flowshop facility. It first states the general Production Planning and Scheduling problem and highlights some drawbacks of classical solutions. A theoretical decomposition-based approach is introduced whose main issue is to overcome non-efficient capacity utilization. By using Branch and Bound methods, an in-depth analysis of the scheduling part of the system is then carried out throughout the study and development of upper and lower bounds as well as branching schemes. Already-existing and new heuristics are presented and compared on different shop floor configurations. Five different heuristic approaches are studied. By scheduling the HFS one stage at a time the first approach uses different stage sequencing orders. The second and third approaches are mainly list heuristics. The second approach uses ideas derived from the multistage classical flowshop with a single machine per stage, while the third approach uses classical dispatching priority rules. The fourth and fifth approaches, respectively, use random scheduling and local search techniques. Statistical analysis is carried out in order to compare the heuristics and to select the best of them for each shop configuration. Already-existing and new lower bounds on the single stage subproblem are also presented and compared. Three new lower bounds are developed: a dual heuristic based bound, a partially preemptive bound and a heuristic for the so-called subset bound. Some of these lower bounds use a network flow algorithm. A new version of the “Preflow Push” algorithm which runs faster than the original one is presented. The best lower bounds are selected based on numerical tests. Two branch and bound algorithms are presented, an improved version of the sequence enumeration method and a generalization of the so-called interval branching method, along with several bounding strategies. Based on the upper and lower bound studies, several branch and bound algorithms are presented and compared using numerical tests on different shop floor configurations. Eventually, an Object Model for Scheduling Algorithm Implementations (OMSAI), that has been used for the computer implementation of the developed algorithms, is presented.
7

Multi-vehicle Mobility Allowance Shuttle Transit (MAST) System - An Analytical Model to Select the Fleet Size and a Scheduling Heuristic

Lu, Wei 2011 August 1900 (has links)
The mobility allowance shuttle transit (MAST) system is a hybrid transit system in which vehicles are allowed to deviate from a fixed route to serve flexible demand. A mixed integer programming (MIP) formulation for the static scheduling problem of a multi-vehicle Mobility Allowance Shuttle Transit (MAST) system is proposed in this thesis. Based on the MIP formulation, we analyze the impacts of time headways between consecutive transit vehicles on the performance of a two-vehicle MAST system. An analytical framework is then developed to model the performance of both one-vehicle and two-vehicle MAST systems, which is used to identify the critical demand level at which an increase of the fleet size from one to two vehicles would be appropriate. Finally, a sensitivity analysis is conducted to find out the impact of a key modeling parameter, w1, the weight of operations cost on the critical demand. In this paper, we develop an insertion heuristic for a multi-vehicle MAST system, which has never been addressed in the literature. The proposed heuristic is validated and evaluated by a set of simulations performed at different demand levels and with different control parameters. By comparing its performance versus the optimal solutions, the effectiveness of the heuristic is confirmed. Compared to its single-vehicle counterpart, the multiple-vehicle MAST prevails in terms of rejection rate, passenger waiting time and overall objective function, among other performance indices.
8

MINIMIZING INTER-CORE DATA-PROPAGATION DELAYS IN PARTITIONED MULTI-CORE REAL-TIME SYSTEMS USING SCHEDULING HEURISTICS

Åberg, Emil January 2021 (has links)
In the field of embedded systems, computers embedded into machines ranging from microwaveovensto assembly lines impact the physical world. They do so under tight real-time constraintswith ever-increasing demand for computing power and performance. Development of higher speedprocessors have been hampered by diminishing returns on power consumption as clock frequency isfurther increased. For this reason, today, embedded processor development is instead moving towardfurther concurrency with multi-core processors being considered more and more every day. Withparallelism comes challenges, such as interference caused by shared resources. Contention betweenprocessor cores, such as shared memory, result in inter-core interference which is potentially unpredictableand unbounded. The focus of this thesis is placed on minimizing inter-core interferencewhile meeting local task timing requirements by utilizing scheduling heuristics. A scheduling heuristicis designed and a prototype scheduler which implements this algorithm is developed. Thescheduler is evaluated on randomly generated test cases, where its ability to keep inter-core datapropagationdelays low across different core counts and utilization values was evaluated. The algorithmis also compared with constraint programming in a real world industrial test case. Theobtained results show that the algorithm can produce schedules with low inter-core delays in a veryshort time, although not being able to optimize them fully compared to constraint programming.
9

A Novel Heuristic Rule for Job Shop Scheduling

Maqsood, Shahid, Khan, M. Khurshid, Wood, Alastair S., Hussain, I. January 2013 (has links)
no / No / Scheduling systems based on traditional heuristic rules, which deal with the complexities of manufacturing systems, have been used by researchers for the past six decades. These heuristics rules prioritise all jobs that are waiting to be processed on a resource. In this paper, a novel Index Based Heuristic (IBH) solution for the Job Shop Scheduling Problem (JSSP) is presented with the objective of minimising the overall Makespan (Cmax). The JSSP is still a challenge to researchers and is far from being completely solved due to its combinatorial nature. JSSP suits the challenges of current manufacturing environments. The proposed IBH calculates the indices of candidate jobs and assigns the job with the lower index value to the available machine. To minimise the gap between jobs, a swap technique is introduced. The swap technique takes candidate jobs for a machine and swaps them without violating the precedence constraint. Several benchmark problems are solved from the literature to test the validity and effectiveness of the proposed heuristic. The results show that the proposed IBH based algorithm outperforms the traditional heuristics and is a valid methodology for JSSP optimization.
10

Heuristic approaches for crane scheduling in ship building

Wen, Charlie Hsiao Kuang, January 2008 (has links)
Thesis (M.S.)--Mississippi State University. Department of Industrial and Systems Engineering. / Title from title screen. Includes bibliographical references.

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