Global ETD Search
Search theses and dissertations gathered from participating repositories worldwide. Every result links back to the library that holds it. No account is needed.
Results
Showing 1 to 20 of 43 for “"Service times"”.
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Queue with Random Arrivals and Exponential Service Times
Queues for service of one kind or another arise in many different fields of activity. In recent years a considerable amount of research has been conducted into the properties of simplified mathemtical models of such queuing systems. Initially, it was my aim to present a short but balanced survey of …
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Approximate solutions for multi-server queuing systems with Erlangian service times and an application to air traffic management
This thesis is concerned with approximations of certain M(t)/G(t)/n(t)/n(t) + q queueing systems. More specifically, we are interested in such systems under very general conditions such as time-varying demand and capacity, and high utilization, including occasional oversaturation. Conditions such …
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Assessment of waiting and service times in public and private health care facilities in Gondar district, North western Ethiopia
… of equitable and acceptable standard of health services to all segments of the population has been the major objective of the 1993 Ethiopian National health policy. However, community based studies on satisfaction with public health care facilities reveal that the majority of the population are …
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Many-Server Queues with Time-Varying Arrivals, Customer Abandonment, and non-Exponential Distributions
… in parallel, are intended to model large-scale service systems such as call centers and health care systems. Such models also have been employed to study communication, computing and manufacturing systems. The heavy-traffic approximations yield relatively simple formulas for quantities …
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Problems in feedback queueing systems with symmetric queue disciplines
… with instantaneous Bernoulli feedback where the service discipline is one of two symmetric disciplines. For the processor sharing queue with exponentially distributed service requirements we analyze the departure process, imbedded queue lengths, and the input and output processes. We determine …
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A large-scale neighborhood search approach to vehicle routing pick-up and delivery problem with time windows under uncertainty
… cost possible under a given/predicted demand and service time scenario. This thesis aims to study a real-world VRPPDTW problem with side-constraints and build solutions that are cost-effective as well as robust to stochasticity in demands and service times. Even without the additional side …
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Generalised analytic queueing network models. The need, creation, development and validation of mathematical and computational tools for the construction of analytic queueing network models capturing more critical system behaviour.
… Validation studies indicate central processor service times are highly variable on the system. More pessimistic predictions assuming this variability are in part verified by observation. The utility of the Generalised Exponential (GE) as a distribution parameterised by mean and variance is …
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Generalised analytic queueing network models. The need, creation, development and validation of mathematical and computational tools for the construction of analytic queueing network models capturing more critical system behaviour.
… Validation studies indicate central processor service times are highly variable on the system. More pessimistic predictions assuming this variability are in part verified by observation. The utility of the Generalised Exponential (GE) as a distribution parameterised by mean and variance is …
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A Generic BI Application for Real-time Monitoring of Care Processes
Patient wait times and care service times are key performance measures for care processes in hospitals. Managing the quality of care delivered by these processes in real-time is challenging. A key challenge is to correlate source medical events to infer the care process states that define patient …
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The allocation of non-identical machines among non-identical servers
… the case of quasirandom input and exponential service times. Machines are assigned to operators with the objective of minimizing an expected cost model of the queuing system. Different classes of machines have different service rates and, for a given class of machines, the service rates are …
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Creation and Simulation of a Model for a Discrete Time Buffer System with Interrupted Poisson Arrivals and Uncorrelated Server Interruptions
… they can be transmitted over the output channel. Service times are constant and the buffer is assumed to be of infinite size. Both arrival stream as well as the service of the packets are subjected to random interruptions described by Bernoulli processes, where the interruption process of the …
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Improving access through stochastic modeling in Veterans Affairs Mental Health Services
… discrete event simulation tool. To simulate wait times, users input arrival rates, service times, patience, probabilities of relapses and probabilities to go from one program to another. We determine that blocking is one of the main drivers of the delays. This model is not only useful for direct …
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Robust optimization for network-based resource allocation problems under uncertainty
… modeling uncertainties in data corresponding to service times, resource availability, supplies and demands, we can generate solutions that are more robust operationally, that is, more likely to be executed or easier to repair when disrupted. The challenges are the following: approaches to achieve …
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Analysis and optimization of the Emergency Department at Beth Israel Deaconess Medical Center via simulation
… to predict future patient arrivals, and a service module that takes into account the fact that service times decrease and capacity increases when the system becomes congested. We show that the simulation model results in predictions of waiting times that closely match those observed in the …
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Generalized techniques for using system execution traces to support software performance analysis
… performance properties, such as response times, service times. The dissertation also proposes a novel technique to auto-construct a dataflow model from the system execution trace, which will be useful in evaluating software performance properties. Finally, it showcases how we can use …
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A Study of Geomorphologic Instantaneous Unit Hydrograph
… by a linear reservoir. Based on a concept of service time, the constants of the linear reservoirs and linear channels are related to the geomorphologic parameters. The linear reservoir is a fictitious reservoir in which the storage is directly proportional to the outflow. The geomorphologic …
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Analysis of congested clients' flows in banking systems: A case study of Standard Bank Namibia
As competition amongst banks increases customer service becomes the only unique factor to consider staying relevant and forging ahead in business. The most frequent complaint of customers at Standard Bank Namibia is the waiting lines. The queuing model used in the analysis was M/M/s which involved …
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Essays on Service Operations with Strategic Customers and Innovative Business Models
… studies operations management problems in service operations and supply chains, analyzing the impact of strategic customers and disruptive technologies. We investigate three problems, and insights from the study of each one illuminate the effect of information and/or strategic customer …
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