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Recent Submissions

Access status: Open Access ,
The Vehicle Scheduling Problem: Models, Complexity and Algorithms
(1988-03-28) Cyrus, James Pemberton; Doctor of Philosophy
The Vehicle Scheduling Problem with time windows (VSP) is concerned with finding a minimum-cost set of vehicle schedules which processes a set of jobs with specified earliest and latest start times, durations and trip times between jobs. This problem is well known to be very difficult to solve. A proof that the VSP decision problem is NP-complete is developed in order to gain a deeper understanding of the reasons for the problem's complexity. The ideas are extended to measuring the difficulty of integer instances of the problem. A graph-theoretic representation of the VSP is combined with ideas related to problem difficulty and this leads to theorems on reducing the difficulty of problem instances. The techniques are aimed at reducing the number and sizes of the time windows, therefore greatly reducing the size of the feasible region. The window reduction methods are shown to be both theoretically and empirically valid. The VSP is formulated as a constrained assignment problem, and the start times of jobs are replaced by time window variables. This new formulation leads to theorems on bounds for the VSP, and to a class of approximation algorithms with strong convergence properties. The algorithms prove to be effective in solving both easy and hard problems. The ideas are extended to produce exact algorithms for the VSP. Extensions of the VSP model to include earliness, waiting time and return trips are formulated. The optimal solutions to some special cases of these problems are developed. The approximation algorithms for the VSP are easily adapted to these extended models. An interactive system is developed to build and test new algorithms. This facility allows fundamental algorithms to be combined to produce new results. The user interfaces allow multiple solution views and manipulations to gain insight into the solution structures.
Access status: Open Access ,
Scheduling Problems in Automated Guided Vehicle Systems
(1984-07-23) Cyrus, James Pemberton; MASTER OF APPLIED SCIENCE
The scheduling problems in Automated Guided Vehicle Systems are investigated. A survey of vehicle routing and scheduling problems is presented. The characteristics of Automated Guided vehicle Systems (AGVS's) are described. A taxonomy is developed for the Vehicle Scheduling Problem in AGVS's, and formulations are presented for the most important problems. Heuristic algorithms are developed to solve three of the scheduling problems in AGVS's: the Vehicle Scheduling Problems (VSP's) with fixed start times and minimum route length and minimum cost objectives, and the minimum-cost VSP with time windows. A fast implementation of the Dilworth decomposition algorithm, 0(n 2 ), is developed to solve the traditional minimum-vehicle VSP as applied to AGVS's. A sub-gradient algorithm is developed to solve the minimum-cost VSP with fixed start times; the algorithm uses a new application of Lagrangian multipliers in an upper-bound heuristic. The algorithms are analysed and the heuristic algorithms are shown to have complexity 0(n 2 ) and also to be capable of solving problems with up to 800 tasks in less than 30 seconds. The solutions to problems with 100 tasks are shown to be within 20 percent of the optimal solutions, for the particular types of data used.
Access status: Open Access ,
The extracellular domain of mGluR6 regulates targeting to the conventional secretion pathway
(2026) Rideout, AP; Abuelatta, OW; Agosto, MA
Access status: Open Access ,
A Critical Analysis of Memorial University's Draft Indigenous Verification Policy
(2026-02-09) Martin, Debbie; Hudson, Amy; Snow, Shannon; Fagan Bidwell, Kristina
Access status: Open Access ,
Fountain of Health Initiative for Optimal Aging
(Dalhousie University Faculty of Health, 2018) Courtney Jean Sheedy
An oral presentation will be given on how The Fountain of Health (FoH) Initiative for Optimal Aging has become a leading movement in positive psychiatry in Canada. The presentation will review how FoH has approached the theoretical issues in health practices and the importance of preventative efforts.
Access status: Open Access ,
Unlocking the Potential of Interprofessional Students to Advance Health Care: Learning from two student led environments
(Dalhousie University Faculty of Health, 2018) Elizabeth Hanna
A three-way partnership between Holland Bloorview Kids Rehabilitation Hospital, University Health Network and the Centre for Interprofessional Education in Toronto has supported the development of interprofessional student led environments in two very different healthcare care settings. These initiatives confirm the value of these placements for students, patients, preceptors and administrators.