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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.
81

The Characterization and Feasibility of a Low-Duty-Cycle Diaphragmless Shock Tube

Taylor, David Christopher 2012 August 1900 (has links)
The feasibility and characterization of a novel diaphragmless shock tube was examined at the National Aerothermochemistry Laboratory at Texas A&M University. The goal was to design a facility that reliably produces shock waves through air in a repeatable manner sufficient for statistical analysis. The device is modular, automated, and compact. The proposed diaphragmless shock tube uses a shock wave generating mechanism that consists of a rotating door and locking cam-shaft system. The facility produced the desired driver gas pressures repeatedly to within 0.31% at low-duty-cycle of 6 seconds. The driven gas pressure profiles within the test-section suggest that shock waves may be forming within test section for a driver gas pressure of 200 psig and above, which corresponds to shock wave Mach numbers of 1.7 to 2.0. The measured wave speeds were within 3.1% of that predicted by ideal shock tube theory; however, the induced driven gas pressures within the constant pressure region were approximately half that expedited from ideal shock tube theory.
82

Mathematical Programming Formulations of the Planar Facility Location Problem

Zvereva, Margarita January 2007 (has links)
The facility location problem is the task of optimally placing a given number of facilities in a certain subset of the plane. In this thesis, we present various mathematical programming formulations of the planar facility location problem, where potential facility locations are not specified. We first consider mixed-integer programming formulations of the planar facility locations problems with squared Euclidean and rectangular distance metrics to solve this problem to provable optimality. We also investigate a heuristic approach to solving the problem by extending the $K$-means clustering algorithm and formulating the facility location problem as a variant of a semidefinite programming problem, leading to a relaxation algorithm. We present computational results for the mixed-integer formulations, as well as compare the objective values resulting from the relaxation algorithm and the modified $K$-means heuristic. In addition, we briefly discuss some of the practical issues related to the facility location model under the continuous customer distribution.
83

Hur kvalitetssäkras en Facility Management upphandling. : Viktig aspekt att tänka på vid outsourcing av den tekniska fastighetsskötseln.

Bohlström, Kristina January 2011 (has links)
Denna rapport handlar om kvalitet på tekniska installationer i fastigheter. Det har blivit allt vanligare inom fastighetsbranschen att organisationer/företag handlar upp FM tjänster som stöd till sin kärnverksamhet. Detta för att kunna effektivisera sin kärnverksamhet och göra kostnadsbesparingar.   Själv har jag arbetat några år som fastighetsförvaltare och då kommit i kontakt med FM tjänster. Funderingar som har funnits hos beställare av FM tjänster på den tekniska sidan har varit om FM leverantör utfört tillsyn och skötsel enligt avtal. Av egen erfarenhet har de uppenbarligen inte gjort tillsyn och skötsel enligt avtalen. Som ett exempel kan nämnas när nödbelysning inte har fungerat vid strömbortfall. Enligt avtalet skulle batterier till nödbelysning kontrolleras med jämna intervaller och bytas ut av FM leverantör. Denna kostnad ingick i det fasta arvodet till FM entreprenören. Eller när tillsyn och skötsel av hängrännor uppenbarligen inte hade rensas på flera år. Följden av det blev frostsprängning i tegelfasaden då det under senhöst/vinter byggde på så mycket mossa, löv och annat skräp att vattnet som rann på fasaden sögs in i tegelfasaden och frös till.   Rapporten handlar inte om specifika fall som ovan utan om det finns några viktiga parametrar att tänka på som beställare av FM tjänster på de tekniska installationerna. Hur kan en beställare av FM tjänster kvalitetssäkra de tekniska installationerna?
84

Mathematical Programming Formulations of the Planar Facility Location Problem

Zvereva, Margarita January 2007 (has links)
The facility location problem is the task of optimally placing a given number of facilities in a certain subset of the plane. In this thesis, we present various mathematical programming formulations of the planar facility location problem, where potential facility locations are not specified. We first consider mixed-integer programming formulations of the planar facility locations problems with squared Euclidean and rectangular distance metrics to solve this problem to provable optimality. We also investigate a heuristic approach to solving the problem by extending the $K$-means clustering algorithm and formulating the facility location problem as a variant of a semidefinite programming problem, leading to a relaxation algorithm. We present computational results for the mixed-integer formulations, as well as compare the objective values resulting from the relaxation algorithm and the modified $K$-means heuristic. In addition, we briefly discuss some of the practical issues related to the facility location model under the continuous customer distribution.
85

A Semidefinite Programming Model for the Facility Layout Problem

Adams, Elspeth January 2010 (has links)
The continuous facility layout problem consists of arranging a set of facilities so that no pair overlaps and the total sum of the pairwise connection costs (proportional to the center-to-center rectilinear distance) is minimized. This thesis presents a completely mixed integer semidefinite programming (MISDP) model for the continuous facility layout problem. To begin we describe the problem in detail; discuss the conditions required for a feasible layout; and define quaternary variables. These variables are the basis of the MISDP model. We prove that the model is an exact formulation and a distinction is made between the constraints that semidefinite programming (SDP) optimization software can solve and those that must be relaxed. The latter are called exactness constraints and three possible exactness constraints are shown to be equivalent. The main contribution of this thesis is the theoretical development of a MISDP model that is based on quaternary, as oppose to binary, variables; nevertheless preliminary computational results will be presented for problems with 5 to 20 facilities. The optimal solution is found for problems with 5 and 6 facilities, confirming the validity of the model; and the potential of the model is revealed as a new upper bound is found for an 11-facility problem.
86

LP-based Approximation Algorithms for the Capacitated Facility Location Problem

Blanco Sandoval, Marco David January 2012 (has links)
The capacitated facility location problem is a well known problem in combinatorial optimization and operations research. In it, we are given a set of clients and a set of possible facility locations. Each client has a certain demand that needs to be satisfied from open facilities, without exceeding their capacity. Whenever we open a facility we incur in a corresponding opening cost. Whenever demand is served, we incur in an assignment cost; depending on the distance the demand travels. The goal is to open a set of facilities that satisfy all demands while minimizing the total opening and assignment costs. In this thesis, we present two novel LP-based approximation algorithms for the capacitated facility location problem. The first algorithm is based on LP-rounding techniques, and is designed for the special case of the capacitated facility location problem where capacities are uniform and assignment costs are given by a tree metric. The second algorithm follows a primal-dual approach, and works for the general case. For both algorithms, we obtain an approximation guarantee that is linear on the size of the problem. To the best of our knowledge, there are no LP-based algorithms known, for the type of instances that we focus on, that achieve a better performance.
87

Identifying Relevant Variables for Understanding How School Facilities Affect Educational Outcomes

Bosch, Sheila Jones 07 January 2004 (has links)
Many school facilities in the United States are old, out-of-date, poorly maintained, and lack specific design elements that are likely to enhance teaching, learning, behavior, and other desirable outcomes. This study proposed that one reason why previous research regarding the effects of the physical school environment on educational outcomes has had little impact on the quality of schools is because there is a lack of knowledge about these relationships. A multi-method approach was used to solicit information from educators and researchers familiar with school facility effects literature to develop a set of research priorities to guide future research. In Phase I, a literature analysis provided important physical and outcome variables to seed brainstorming lists used in following phases of the research and provided the basis for a gap analysis to identify unavailable information. A concept mapping methodology was utilized in Phase II to solicit feedback from a group of seventeen experienced educators who were asked to brainstorm a list of measures of student, school, or school district success, sort their final list of more than 100 items into categories that made sense to them, and rate each item regarding how important it is to monitor or otherwise track. Using a Delphi method, a series of four questionnaires was given to a group of experienced researchers who developed a list of physical variables plausibly related to educational outcomes, rated the importance of those items, developed hypotheses that included top-rated physical variables and top-rated outcome variables (i.e., measures of success rated by educators), and then selected from those hypotheses several that became the basis of the recommended research priorities for the field. These research priorities propose investigations of the relationships between a set of physical variables (including the provision of team work stations and faculty collaborative spaces, well-designed circulation spaces, spaces for quiet reflection, adaptable seating, daylighting in classrooms, and overall maintenance and building quality) and a variety of educational outcomes (e.g., achievement, behavior, satisfaction, affective performance).
88

Joint optimization of location and inventory decisions for improving supply chain cost performance

Keskin, Burcu Baris 15 May 2009 (has links)
This dissertation is focused on investigating the integration of inventory and facility location decisions in different supply chain settings. Facility location and inventory decisions are interdependent due to the economies of scale that are inherent in transportation and replenishment costs. The facility location decisions have an impact on the transportation and replenishment costs which, in turn, affect the optimal inventory policy. On the other hand, the inventory policy dictates the frequency of shipments to replenish inventory which, in turn, affects the number of deliveries, and, hence, the transportation costs, between the facilities. Therefore, our main research objectives are to: • compare the optimal facility location, determined by minimizing total transportation costs, to the one determined by the models that also consider the timing and quantity of inventory replenishments and corresponding costs, • investigate the effect of facility location decisions on optimal inventory decisions, and • measure the impact of integrated decision-making on overall supply chain cost performance. Placing a special emphasis on the explicit modeling of transportation costs, we develop several novel models in mixed integer linear and nonlinear optimization programming. Based on how the underlying facility location problem is modeled, these models fall into two main groups: 1) continuous facility location problems, and 2) discrete facility location problems. For the stylistic models, the focus is on the development of analytical solutions. For the more general models, the focus is on the development of efficient algorithms. Our results demonstrate • the impact of explicit transportation costs on integrated decisions, • the impact of different transportation cost functions on integrated decisions in the context of continuous facility location problems of interest, • the value of integrated decision-making in different supply chain settings, and • the performance of solution methods that jointly optimize facility location and inventory decisions.
89

Community Hospitals' Vertical Integration into Nursing Facilities: A Resource Dependence Perspective

Lo, Jen-Pei 28 August 2004 (has links)
Research Objective The purpose of this study is to profile market factors and organizational characteristics associated with community hospitals¡¦ vertical integration into a nursing facility through the lens of resource dependence. Data Sources Data for this study were drawn from three sources: the 2002 secondary data collected by Taiwan Community Hospital Association (TCHA) on a regular yearly basis; the 2001 secondary data compiled by Taiwan Association of Long-Term Care Professionals (TALTCP); and the 2002 area-based population data gathered by Department of Budget, Accounting, and Statistics (DOBAS) in local governments respectively. Study Design This study is a one-year cross-sectional design with community hospitals as the unit of analysis. A sample of 248 community hospitals was the focus of this study. Since the dependent variable is dichotomous, the logistic procedure was used to fit the regression. The analysis was performed using the statistics software, SPSS 10.0. Findings A higher ratio of the elderly, a high degree of competition, and the provision of dialysis and home care services spur community hospitals on to vertical integration into a nursing facility. Occupancy rate, the rehabilitative service, respiratory care service, high technology, the ratio of MDs to staffed beds, as well as the ratio of RNs and LPNs to staffed beds bear no reference to community hospitals¡¦ vertically integrating a nursing facility. Conclusion Not all community hospitals are equally good candidates for stepping into the avenue to nursing facility. Given the environmental factors, community hospitals situated in highly competitive district areas with a higher ratio of the elderly are more likely to vertically integrate a nursing facility. In terms of organizational factors, the provisions of dialysis service and home care service have a significant relationship with the likelihood of vertical integration.
90

Investigation of industrial wastewater and treatment facility performance of A-gong-dian river basin

Li, Tsai-yu 04 July 2009 (has links)
The water quality of rivers currently is seriously polluted in Taiwan for influencing drinking water quality, harming onto plants growth caused soil pollution problems by using river irrigation and harming the human health indirectly by contamination in river sediments. In this work, we will investigate the area of river water quality characteristics and pollution sources to solve effectively for the pollution problems in the river area of A-Gong-Den in Kaohsiung County. The source of the river area of this study is dam of A-Gong-Den. Their water quality is polluted majorly by the domestic and industrial wastewater. The dark red-color of river body was due to the effluent from those industrial factories. Heavy metals such as Zn, total Cr ions and conductivity were all over the water quality standard of irrigation uses. Thus, we will try to improve the color problems in this area of river by diagnostics method in five factories having wastewater treatment plants. The effective solution in management and controlling will be discussed. We investigate the treatment facilities and performance evaluation in five industrial plants. We found the wastewater treatment and operation technology should be done and elevated in some factories. Importantly, the marked signs in pipelines in wastewater treatment were not clear and operated under not normal conditions. The EPA in county should send officers for checking the operations of the wastewater treatment plants in listings with a normal period for once.

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