You searched for +publisher:"University of Texas – Austin" +contributor:("Khajavirad, Aida").
Showing records 1 – 5 of
5 total matches.
No search limiters apply to these results.
University of Texas – Austin
1.
-9907-6069.
Simulation and optimization techniques applied in semiconductor assembly and test operations.
Degree: PhD, Operations research and industrial engineering, 2016, University of Texas – Austin
URL: http://hdl.handle.net/2152/40318 
► The importance of back-end operations in semiconductor manufacturing has been growing steadily in the face of higher customer expectations and stronger competition in the industry.…
(more)
▼ The importance of back-end operations in semiconductor manufacturing has been growing steadily in the face of higher customer expectations and stronger competition in the industry. In order to achieve low cycle times, high throughput, and high utilization while improving due-date performance, more effective tools are needed to support machine setup and lot dispatching decisions. In previous work, the problem of maximizing the weighted throughput of lots undergoing assembly and test (AT), while ensuring that critical lots are given priority, was investigated and a greedy randomized adaptive search procedure (GRASP) developed to find solutions. Optimization techniques have long been used for scheduling manufacturing operations on a daily basis. Solutions provide a prescription for machine setups and job processing over a finite the planning horizon. In contrast, simulation provides more detail but in a normative sense. It tells you how the system will evolve in real time for a given demand, a given set of resources and rules for using them. A simulation model can also accommodate changeovers, initial setups and multi-pass requirements easily. The first part of the research is to show how the results of an optimization model can be integrated with the decisions made within a simulation model. The problem addressed is defined in terms of four hierarchical objectives: minimize the weighted sum of key device shortages, maximize weighted throughput, minimize the number of machines used, and minimize makespan for a given set of lots in queue, and a set of resources that includes machines and tooling. The facility can be viewed as a reentrant flow shop. The basic simulation was written in AutoSched AP (ASAP) and then enhanced with the help of customization features available in the software. Several new dispatch rules were developed. Rule_First_setup is able to initialize the simulation with the setups obtained with the GRASP. Rule_All_setups enables a machine to select the setup provided by the optimization solution whenever a decision is about to be made on which setup to choose subsequent to the initial setup. Rule_Hotlot was also proposed to prioritize the processing of the hot lots that contain key devices. The objective of the second part of the research is to design and implement heuristics within the simulation model to schedule back-end operations in a semiconductor AT facility. Rule_Setupnum lets the machines determine which key device to process according to a machine setup frequency table constructed from the GRASP solution. GRASP_asap embeds a more robust selection features of GRASP in the ASAP model through customization. This allows ASAP to explore a larger portion of the feasible region at each decision point by randomizing machine setups using adaptive probability distributions that are a function of solution quality. Rule_Greedy, which is a simplification of GRASP_asap, always picks the setup for a particular machine that gives the greatest marginal improvement in the objective function among all candidates.…
Advisors/Committee Members: Bard, Jonathan F. (advisor), Morrice, Douglas J (committee member), Hasenbein, John (committee member), Khajavirad, Aida (committee member), Gao, Zhufeng (committee member).
Subjects/Keywords: Semiconductor assembly and test; AutoSched; GRASP; Dispatch rules; Statistical analysis; Machine setup; Reentrant flow
Record Details
Similar Records
Cite
Share »
Record Details
Similar Records
Cite
« Share
❌
APA ·
Chicago ·
MLA ·
Vancouver ·
CSE |
Export
to Zotero / EndNote / Reference
Manager
APA (6th Edition):
-9907-6069. (2016). Simulation and optimization techniques applied in semiconductor assembly and test operations. (Doctoral Dissertation). University of Texas – Austin. Retrieved from http://hdl.handle.net/2152/40318
Note: this citation may be lacking information needed for this citation format:
Author name may be incomplete
Chicago Manual of Style (16th Edition):
-9907-6069. “Simulation and optimization techniques applied in semiconductor assembly and test operations.” 2016. Doctoral Dissertation, University of Texas – Austin. Accessed February 28, 2021.
http://hdl.handle.net/2152/40318.
Note: this citation may be lacking information needed for this citation format:
Author name may be incomplete
MLA Handbook (7th Edition):
-9907-6069. “Simulation and optimization techniques applied in semiconductor assembly and test operations.” 2016. Web. 28 Feb 2021.
Note: this citation may be lacking information needed for this citation format:
Author name may be incomplete
Vancouver:
-9907-6069. Simulation and optimization techniques applied in semiconductor assembly and test operations. [Internet] [Doctoral dissertation]. University of Texas – Austin; 2016. [cited 2021 Feb 28].
Available from: http://hdl.handle.net/2152/40318.
Note: this citation may be lacking information needed for this citation format:
Author name may be incomplete
Council of Science Editors:
-9907-6069. Simulation and optimization techniques applied in semiconductor assembly and test operations. [Doctoral Dissertation]. University of Texas – Austin; 2016. Available from: http://hdl.handle.net/2152/40318
Note: this citation may be lacking information needed for this citation format:
Author name may be incomplete
University of Texas – Austin
2.
-9322-9685.
Discovering latent structures in syntax trees and mixed-type data.
Degree: PhD, Operations Research and Industrial Engineering, 2016, University of Texas – Austin
URL: http://hdl.handle.net/2152/68368
► Gibbs sampling is a widely applied algorithm to estimate parameters in statistical models. This thesis uses Gibbs sampling to resolve practical problems, especially on natural…
(more)
▼ Gibbs sampling is a widely applied algorithm to estimate parameters in statistical models. This thesis uses Gibbs sampling to resolve practical problems, especially on natural language processing and mixed type data. It includes three independent studies. The first study includes a Bayesian model for learning latent annotations. The technique is capable of parsing sentences in a wide variety of languages, producing results that are on-par with or surpass previous approaches in accuracy, and shows promising potential for parsing low-resource languages. The second study presents a method to automatically complete annotations from partially-annotated sentence data, with the help of Gibbs sampling. The algorithm significantly reduces the time required to annotate sentences for natural language processing, without a significant drop in annotation accuracy. The last study proposes a novel factor model for uncovering latent factors and exploring covariation among multiple outcomes of mixed types, including binary, count, and continuous data. Gibbs sampling is used to estimate model parameters. The algorithm successfully discovers correlation structures of mixed-type
data in both simulated and real-word data.
Advisors/Committee Members: Dimitrov, Nedialko B. (advisor), Baldridge, Jason (committee member), Hasenbein, John (committee member), Khajavirad, Aida (committee member), Scott, James (committee member).
Subjects/Keywords: Gibbs sampling; Natural language processing; Bayesian statistics; Factor analysis; Syntax trees parsing
Record Details
Similar Records
Cite
Share »
Record Details
Similar Records
Cite
« Share
❌
APA ·
Chicago ·
MLA ·
Vancouver ·
CSE |
Export
to Zotero / EndNote / Reference
Manager
APA (6th Edition):
-9322-9685. (2016). Discovering latent structures in syntax trees and mixed-type data. (Doctoral Dissertation). University of Texas – Austin. Retrieved from http://hdl.handle.net/2152/68368
Note: this citation may be lacking information needed for this citation format:
Author name may be incomplete
Chicago Manual of Style (16th Edition):
-9322-9685. “Discovering latent structures in syntax trees and mixed-type data.” 2016. Doctoral Dissertation, University of Texas – Austin. Accessed February 28, 2021.
http://hdl.handle.net/2152/68368.
Note: this citation may be lacking information needed for this citation format:
Author name may be incomplete
MLA Handbook (7th Edition):
-9322-9685. “Discovering latent structures in syntax trees and mixed-type data.” 2016. Web. 28 Feb 2021.
Note: this citation may be lacking information needed for this citation format:
Author name may be incomplete
Vancouver:
-9322-9685. Discovering latent structures in syntax trees and mixed-type data. [Internet] [Doctoral dissertation]. University of Texas – Austin; 2016. [cited 2021 Feb 28].
Available from: http://hdl.handle.net/2152/68368.
Note: this citation may be lacking information needed for this citation format:
Author name may be incomplete
Council of Science Editors:
-9322-9685. Discovering latent structures in syntax trees and mixed-type data. [Doctoral Dissertation]. University of Texas – Austin; 2016. Available from: http://hdl.handle.net/2152/68368
Note: this citation may be lacking information needed for this citation format:
Author name may be incomplete
University of Texas – Austin
3.
-1709-7032.
Resource allocation in service and logistics systems.
Degree: PhD, Operations Research & Industrial Engineering, 2016, University of Texas – Austin
URL: http://hdl.handle.net/2152/47042
► Resource allocation is a problem commonly encountered in strategic planning, where a typical objective is to minimize the associated cost or maximize the resulting profit.…
(more)
▼ Resource allocation is a problem commonly encountered in strategic planning, where a typical objective is to minimize the associated cost or maximize the resulting profit. It is studied analytically and numerically for service and logistics systems in this dissertation, with the major resource being people, services or trucks. First, a staffing level problem is analyzed for large-scale single-station queueing systems. The system manager operates an Erlang-C queueing system with a quality-of-service (QoS) constraint on the probability that a customer is queued. However, in this model, the arrival rate is uncertain in the sense that even the arrival-rate distribution is not completely known to the manager. Rather, the manager has an estimate of the support of the arrival-rate distribution and the mean. The goal is to determine the number of servers needed to satisfy the quality of service constraint. Two models are explored. First, the constraint is enforced on an overall delay probability, given the probability that different feasible arrival-rate distributions are selected. In the second case, the constraint has to be satisfied by every possible distribution. For both problems, asymptotically optimal solutions are developed based on Halfin-Whitt type scalings. The work is followed by a discussion on solution uniqueness with a joint QoS constraint and a given arrival-rate distribution in multi-station systems. Second, an extension to Naor’s analysis on the joining or balking problem in observable M=M=1 queues and its variant in unobservable M=M=1 queues is presented to incorporate parameter uncertainty. The arrival-rate distribution is known to all, but the exact arrival rate is unknown in both cases. The optimal joining strategies are obtained and compared from the perspectives of individual customers, the social optimizer and the profit maximizer, where differences are recognized between the results for systems with deterministic and stochastic arrival rates. Finally, an integrated ordering and inbound shipping problem is formulated for an assembly plant with a large number of suppliers. The objective is to minimize the annual total cost with a static strategy. Potential transportation modes include full truckload shipping and less than truckload shipping, the former of which allows customized routing while the latter does not. A location-based model is applied in search of near-optimal solutions instead of an exact model with vehicle routing, and numerical experiments are conducted to investigate the insights of the problem.
Advisors/Committee Members: Hasenbein, John J. (advisor), Kutanoglu, Erhan (advisor), Bickel, James E. (committee member), Khajavirad, Aida (committee member), Morrice, Douglas J. (committee member).
Subjects/Keywords: Staffing service systems; Parameter uncertainty; Game-theoretic queueing; Inbound shipping
Record Details
Similar Records
Cite
Share »
Record Details
Similar Records
Cite
« Share
❌
APA ·
Chicago ·
MLA ·
Vancouver ·
CSE |
Export
to Zotero / EndNote / Reference
Manager
APA (6th Edition):
-1709-7032. (2016). Resource allocation in service and logistics systems. (Doctoral Dissertation). University of Texas – Austin. Retrieved from http://hdl.handle.net/2152/47042
Note: this citation may be lacking information needed for this citation format:
Author name may be incomplete
Chicago Manual of Style (16th Edition):
-1709-7032. “Resource allocation in service and logistics systems.” 2016. Doctoral Dissertation, University of Texas – Austin. Accessed February 28, 2021.
http://hdl.handle.net/2152/47042.
Note: this citation may be lacking information needed for this citation format:
Author name may be incomplete
MLA Handbook (7th Edition):
-1709-7032. “Resource allocation in service and logistics systems.” 2016. Web. 28 Feb 2021.
Note: this citation may be lacking information needed for this citation format:
Author name may be incomplete
Vancouver:
-1709-7032. Resource allocation in service and logistics systems. [Internet] [Doctoral dissertation]. University of Texas – Austin; 2016. [cited 2021 Feb 28].
Available from: http://hdl.handle.net/2152/47042.
Note: this citation may be lacking information needed for this citation format:
Author name may be incomplete
Council of Science Editors:
-1709-7032. Resource allocation in service and logistics systems. [Doctoral Dissertation]. University of Texas – Austin; 2016. Available from: http://hdl.handle.net/2152/47042
Note: this citation may be lacking information needed for this citation format:
Author name may be incomplete
University of Texas – Austin
4.
-1860-9725.
Analysis, design and implementation of models for housestaff scheduling at outpatient clinics and improving patient flow at a family health clinic.
Degree: PhD, Operations Research and Industrial Engineering, 2015, University of Texas – Austin
URL: http://hdl.handle.net/2152/31603
► Clinical experiences during the three years of residencies occur in inpatient and outpatient settings on generalist and specialist clinical services. Housestaff rotate through different clinical…
(more)
▼ Clinical experiences during the three years of residencies occur in inpatient and outpatient settings on generalist and specialist clinical services. Housestaff rotate through different clinical experiences monthly, with their primary care clinic time overlaid longitudinally on these other clinical services. The primary goals of this research are to construct housestaff schedules and improve efficiencies for residency programs. In the first phase of the research, we developed two models for constructing monthly clinic schedules for housestaff training in Internal Medicine. In our first model, the objective is to both maximize clinic utilization and minimize the number of violations of a prioritized set of goals while ensuring that certain clinic-level and individual constraints are satisfied. The corresponding problem is formulated as an integer goal program in which several of the hard constraints are temporarily allowed to be violated to avoid infeasibility. A three-phase methodology is then proposed to find solutions. The second model solves a similar problem with the objective of maximizing the number of interns and residents that are assigned clinic duty each month during their training in Internal Medicine. A complexity analysis is provided that demonstrates that the basic problem can be modeled as a pure network and the full problem can be modeled as a network with gains. In the second phase of the research, the goal was to redesign the monthly templates that comprise the annual block rotations to obtain better housestaff schedules. To implement this model, we investigate two different programs: Family Medicine and Internal Medicine. The problems were formulated as mixed-integer programs but proved too difficult to solve exactly. As an alternative, several heuristics were developed that yielded good feasible solutions. For the last part of the research, we focused on improving patient flow at a family health clinic. The objective was to obtain a better understanding of patient flow through the clinic and to investigate changes to current scheduling rules and operating procedures. Discrete event simulation was used to establish a baseline and to evaluate a variety of scenarios associated with appointment scheduling and managing early and late arrivals.
Advisors/Committee Members: Bard, Jonathan F. (advisor), Morrice, Douglas J. (Douglas John), 1962- (advisor), Khajavirad, Aida (committee member), Dimitrov, Ned (committee member), Leykum, Luci (committee member).
Subjects/Keywords: Resident scheduling; Residency outpatient clinic; Medical rotations; Goal programming; Mixed-integer programming; Patient flow; Simulation; Performance analysis
Record Details
Similar Records
Cite
Share »
Record Details
Similar Records
Cite
« Share
❌
APA ·
Chicago ·
MLA ·
Vancouver ·
CSE |
Export
to Zotero / EndNote / Reference
Manager
APA (6th Edition):
-1860-9725. (2015). Analysis, design and implementation of models for housestaff scheduling at outpatient clinics and improving patient flow at a family health clinic. (Doctoral Dissertation). University of Texas – Austin. Retrieved from http://hdl.handle.net/2152/31603
Note: this citation may be lacking information needed for this citation format:
Author name may be incomplete
Chicago Manual of Style (16th Edition):
-1860-9725. “Analysis, design and implementation of models for housestaff scheduling at outpatient clinics and improving patient flow at a family health clinic.” 2015. Doctoral Dissertation, University of Texas – Austin. Accessed February 28, 2021.
http://hdl.handle.net/2152/31603.
Note: this citation may be lacking information needed for this citation format:
Author name may be incomplete
MLA Handbook (7th Edition):
-1860-9725. “Analysis, design and implementation of models for housestaff scheduling at outpatient clinics and improving patient flow at a family health clinic.” 2015. Web. 28 Feb 2021.
Note: this citation may be lacking information needed for this citation format:
Author name may be incomplete
Vancouver:
-1860-9725. Analysis, design and implementation of models for housestaff scheduling at outpatient clinics and improving patient flow at a family health clinic. [Internet] [Doctoral dissertation]. University of Texas – Austin; 2015. [cited 2021 Feb 28].
Available from: http://hdl.handle.net/2152/31603.
Note: this citation may be lacking information needed for this citation format:
Author name may be incomplete
Council of Science Editors:
-1860-9725. Analysis, design and implementation of models for housestaff scheduling at outpatient clinics and improving patient flow at a family health clinic. [Doctoral Dissertation]. University of Texas – Austin; 2015. Available from: http://hdl.handle.net/2152/31603
Note: this citation may be lacking information needed for this citation format:
Author name may be incomplete
University of Texas – Austin
5.
Sisbot, Emre Arda.
Fluid and queueing networks with Gurvich-type routing.
Degree: PhD, Operations research and industrial engineering, 2015, University of Texas – Austin
URL: http://hdl.handle.net/2152/32536
► Queueing networks have applications in a wide range of domains, from call center management to telecommunication networks. Motivated by a healthcare application, in this dissertation,…
(more)
▼ Queueing networks have applications in a wide range of domains, from call center management to telecommunication networks. Motivated by a healthcare application, in this dissertation, we analyze a class of queueing and fluid networks with an additional routing option that we call Gurvich-type routing. The networks we consider include parallel buffers, each associated with a different class of entity, and Gurvich-type routing allows to control the assignment of an incoming entity to one of the classes. In addition to routing, scheduling of entities is also controlled as the classes of entities compete for service at the same station. A major theme in this work is the investigation of the interplay of this routing option with the scheduling decisions in networks with various topologies. The first part of this work focuses on a queueing network composed of two parallel buffers. We form a Markov decision process representation of this system and prove structural results on the optimal routing and scheduling controls. Via these results, we determine a near-optimal discrete policy by solving the associated fluid model along with perturbation expansions. In the second part, we analyze a single-station fluid network composed of N parallel buffers with an arbitrary N. For this network, along with structural proofs on the optimal scheduling policies, we show that the optimal routing policies are threshold-based. We then develop a numerical procedure to compute the optimal policy for any initial state. The final part of this work extends the analysis of the previous part to tandem fluid networks composed of two stations. For two different models, we provide results on the optimal scheduling and routing policies.
Advisors/Committee Members: Hasenbein, John J. (advisor), Bickel, James Eric (committee member), Cudina, Milica (committee member), Djurdjanovic, Dragan (committee member), Khajavirad, Aida (committee member).
Subjects/Keywords: Markov decision processes; Queueing theory; Optimal control; Fluid model; Scheduling; Routing
Record Details
Similar Records
Cite
Share »
Record Details
Similar Records
Cite
« Share
❌
APA ·
Chicago ·
MLA ·
Vancouver ·
CSE |
Export
to Zotero / EndNote / Reference
Manager
APA (6th Edition):
Sisbot, E. A. (2015). Fluid and queueing networks with Gurvich-type routing. (Doctoral Dissertation). University of Texas – Austin. Retrieved from http://hdl.handle.net/2152/32536
Chicago Manual of Style (16th Edition):
Sisbot, Emre Arda. “Fluid and queueing networks with Gurvich-type routing.” 2015. Doctoral Dissertation, University of Texas – Austin. Accessed February 28, 2021.
http://hdl.handle.net/2152/32536.
MLA Handbook (7th Edition):
Sisbot, Emre Arda. “Fluid and queueing networks with Gurvich-type routing.” 2015. Web. 28 Feb 2021.
Vancouver:
Sisbot EA. Fluid and queueing networks with Gurvich-type routing. [Internet] [Doctoral dissertation]. University of Texas – Austin; 2015. [cited 2021 Feb 28].
Available from: http://hdl.handle.net/2152/32536.
Council of Science Editors:
Sisbot EA. Fluid and queueing networks with Gurvich-type routing. [Doctoral Dissertation]. University of Texas – Austin; 2015. Available from: http://hdl.handle.net/2152/32536
. 
Open Access Theses and Dissertations