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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.
61

Interdomain Traffic Engineering for Multi-homed Networks

Gao, Ruomei 24 August 2007 (has links)
Interdomain traffic engineering (TE) controls the flow of traffic between autonomous systems (ASes) to achieve performance goals under various resource constraints. Interdomain TE can be categorized into ingress TE and egress TE, which aim to control the ingress and egress traffic flow in a network, respectively. Most interdomain TE techniques are based on BGP, which was not designed to support performance based routing. Hence even though some basic interdomain TE techniques are widely deployed, their overall effectiveness and impact on interdomain traffic are not well understood. Furthermore, systematic practices for deploying these techniques have yet to be developed. In this thesis, we explore these open issues for both ingress and egress TE. We first focus on the AS-Path prepending technique in interdomain ingress TE. We design a polynomial algorithm that takes network settings as input and produces the optimal prepending at each ingress link. We also develop methods to measure the inputs of the optimal algorithm by leveraging widely available looking glass severs and evaluate the errors of such measurement. We further propose an algorithm, based on this optimal algorithm, that is robust to input errors. We then focus on Intelligent Routing Control (IRC) systems often used at multihomed networks for egress interdomain TE. To address the possible traffic oscillation problem caused by multiple IRC systems, we design a class of randomized IRC algorithms. Through simulations, we show that the proposed algorithms can effectively mitigate oscillations. We also show that IRC systems using randomized path switching algorithms perform better than those switching path deterministically, when both types of IRC systems co-exist. To further understand the performance impact of IRC systems, we next focus on the performance of applications, such as TCP connections. We study the synergistic and antagonistic interactions between IRC and TCP connections, through a simple dual-feedback model. We first examine the impact of sudden RTT and available bandwidth changes in TCP connection. We then examine the effect of IRC measurement delays on closed loop traffic. We also show the conditions under which IRC is beneficial under various path impairment models.
62

Development of Quality Assurance Methods for Performance-Based Maintenance Contracts for Roadway Assets

Shelton, Debora Brooke 2010 December 1900 (has links)
Performance-based Maintenance Contracts (PBMCs) are increasingly being used for roadway maintenance as an alternative to method-based specifications. However, this technique is still relatively new and several issues have not been adequately addressed in the literature. The paper provides a systematic process for developing quality assurance measures to be used within these contracts. The process addresses key issues, including the development of performance standards and targets, a method for monitoring the roadside performance, and a methodology for developing pay adjustment factors. The developed performance standards presented in the paper are easily measured and assigned grades of pass, fail, or not applicable. The required sample size is a function of the project characteristics, including performance variability along the project, required confidence level, and allowable tolerance. Finally, the pay adjustment curves are a function of the initial project LOS, the target LOS, and the maintenance cost to achieve the target LOS.
63

An Asset Management Framework Based on Field Performance of Pavement Markings

Madiri, Sam 2010 May 1900 (has links)
Performance-based asset management provides a strategic framework for managing transportation infrastructure to improve existing procedures for resource allocation. The importance of comprehensive management of pavement marking assets not only results in monetary benefits to the agencies but also complements other management systems in providing safer driving conditions. A majority of research concerned with pavement markings addresses installation, performance, maintenance, and economic evaluation. Although agencies have developed guides and manuals on these subjects, they had difficulties in practical implementation. The purpose of this study was to address the issues that were identified in the practical implementation of analytical and information tools of asset management practice in the field of pavement markings. Problems of limited variable data, censored data and uncertainty in field evaluation and retroreflectivity based prediction were addressed by adopting statistical techniques. Sectional assessment and management methods were proposed as a part of a practical restriping methodology. An information tool was developed in a geographic information system (GIS) environment as an application. Retroreflectivity was the only performance measure on which the analysis and application was carried out. Two case studies were conducted, one for statistical techniques with retroreflectivity data collected by the National Transportation Product Evaluation Program (NTPEP) on U.S. Highway 78 westbound, Lee County, Mississippi. The other for application with retroreflectivity data collected using mobile retroreflectivity unit (MRU) on FM 57, Fisher County, Texas. This research effort provides a framework for an agency in developing a pavement marking management program to maintain good visibility of markings. It also provides a basis for further research in building an integrated asset management system based on other transportation assets.
64

3D CFD Simulation Analysis and Experimental Investigation of the Performance-based Smoke Management System Designs of a Building with Large Space

Yeh, Tsung-Chyn 08 August 2006 (has links)
The existing local fire code ¡§Standard for Installation of Fire Protection Facilities in Classified Areas¡¨ is prescriptive in nature and suitable for buildings, which can be well compartmented. It also described the minimum requirement for specific system designs such as fire and smoke compartmentation, mechanical smoke extraction rate, etc. on item 188. In this reserch, the concourse level encountered large spaces and is the vital part for passengers¡¦ movement, either under normal condition or in emergency cases. Therefore, a performance-based fire engineering design has been exercised which is also allowed in local fire code subject to approval from the authorities having jurisdiction. First, a comparative study of the code compliances should be addressed, with the alternative design options supported by 3D CFD simulation. The FDS (Fire Dynamic Simulation) program was utilized for this reserch for 3D CFD simulation. It is developed by the National Institute of Standards and Technology (NIST) of U.S.. FDS is a computational fluid dynamics (CFD) model of fire-driven fluid flow. The software solves numerically a form of the Navier-Stokes equations appropriate for thermally-driven flow with an emphasis on smoke and heat transport from fires. Secondly, it is decided that a full-scale hot smoke test should be conducted to validate the smoke management system performances under the as-built conditions. It can be summarized that, following the NFPA 92B N-percentage Criteria, both test 1 and test 2 results indicated that the hot smoke tests are successful, in validating that a sufficient smoke clear height can be maintained for safe evacuation should a 5 MW t-squared fast fire occurred at the concourse level. Finally, following the NFPA 130 and NFPA 92B as the design guides, the performance-based fire safety engineering design conducted in concourse level, is successful through 3D CFD simulations and full-scale hot smoke test. A smoke¡Vfree escape route can be maintained for a period of time much longer than needed for the worst case fire scenario which warrants a safe evacuation in case of a 5 MW fire occurred on concourse level.
65

Performance Based Ratemaking In Electric Distribution Services

Uguz, Mustafa 01 December 2006 (has links) (PDF)
Regulation is one of the main elements in electric distribution services. The objective of the regulation is to maintain the balance between the rates and the service quality of electric distribution on behalf of both utilities and customers. In rapidly changing world the regulation regimes are also changing .In this thesis, an increasingly implemented regulation model in electric distribution, performance based ratemaking is studied. Its advantages and disadvantages, implementing methods and its quality effects are analyzed.
66

Värdering av en stressad livssituation

Larsson, Lina January 2009 (has links)
<p>The aim of this study was to examine if performance-based self-esteem, personality (Type A), perceived stress, age and gender predict the value of own or others life-stress (VLS). The aim was also to examine whether the variables were correlated significantly with each other. The investigation was conducted in a town in the mid-south of Sweden. The instrument consisted of two forms where the first measured Type A personality and the second tapped perform-ance-based self-esteem, perceived stress and the level of life-stress. The results showed that the level of life-stress could explain, on the basis of the predictors, performance-based self-esteem, personality (Type A), perceived stress, age and gender. Perceived stress was signifi-cantly correlated with VLS when Spearman’s test was performed but it was not a significant predictor in the MRA. Performance-based self-esteem and perceived stress were higher among the younger participants. Gender differences were found where men valued a higher level of a stressed life situation, more than women. The results also showed that a higher score on Type-A behavior resulted in a higher value of a stressed life situation.</p>
67

The social construction of performance-based design

Powell, Ashleigh Boerder 24 April 2013 (has links)
Construction and operation of commercial and residential buildings in the United States have been identified as the single largest sector of energy consumption and contributor to greenhouse gas emissions. Subsequently, buildings must be a primary target for reductions. From short-term incentives, to long-term milestones, building energy efficiency, specifically net zero energy buildings, have emerged as a significant and unprecedented objective for a variety of public and private organizations in the United States. Altering the practices of the building culture requires not only technological innovation, but also an understanding of how practitioners within the building culture see their role in transforming it. Consequently my research seeks to understand how building industry professionals comprehend their capacity to influence the cultural boundaries of their profession in order to account for and mitigate the impacts of energy and emissions in the built environment. Ultimately, this study is an investigation into the social construction of technological change. The AIA+2030 Professional Series offered by the Denver Chapter of the American Institute of Architects has served as the single case study for this investigation. By limiting local conditions to the Denver-based Series and defining advocates as the self-selected group of participants, I’ve narrowed this analysis to reflect a workable microcosm of practitioners who are committed to the investigation and integration of net zero energy design, construction, and building operation practices. In order to substantiate this empirical analysis, I employed a triangulated series of data collection and interpretation consisting of: participant observation, interviews, and a survey. Data analysis involved an iterative process of coding and categorizing the primary key words and themes that emerged throughout my investigation. Each of the perspectives offered during this investigation indicate that architects who are advocates of net zero energy building design perceive that consequential opportunities for fundamental change exist within the social and cultural facets of the building culture. Ultimately, by preferencing social and cultural activism over technological manipulation, these advocates have corroborated the notion that technological change is fundamentally rooted in social change. / text
68

Making sense of performance pay : sensemaking and sensegiving in teachers' implementation of compensation reform

Herbert, Karen Shellberg 09 February 2011 (has links)
Teacher compensation reforms have been on the rise in recent years, yet research has yet to fully demonstrate how teachers interpret these policies and how they may influence their instructional practices and professional decisions. This qualitative study of a performance pay program in an urban district in Texas drew on cognitive approaches to policy implementation and theories of sensemaking to examine and explicate these issues. Teachers’ experiences in two schools were examined through interviews, focus groups, and document analysis. The experiences of school principals and district policymakers acting as sensegivers to teachers about the program’s goals, purposes, and theory of action were also examined. District policymakers’ understandings of the program varied, and were informed by their positions in the system and their own interests in the program. These differences resulted in a complex program with an array of objectives for teachers to implement in schools and classrooms, as well as varying expectations for teachers’ work, which were not always understood by teachers. With few clear and consistent messages from policymakers, teachers and principals interpreted the program according to their own ideas about important outcomes, and then shaped it to fit their situations. Although accepting of the program, teachers and principals were not always able to focus on it in ways expected by policymakers given other demands on them, particularly those emanating from the accountability system. Some evidence of goal distortion in terms of teachers’ attention to student assignments and mobility was also found. These findings hold implications for cognitive theories of policy implementation, suggesting that teachers’ responses to policies are influenced by the amount of attention they are able to give them, as well as direct sensegiving about policy goals and expectations on the part of policymakers. The findings also suggest that performance pay programs can be expected to be adapted, co-opted, and selectively attended to in order to fit within the contexts in which they are implemented. Thus, policymakers should consider other demands in the policy environment that may compete with performance incentives, as well as the organizational contexts of schools in which they will be implemented. / text
69

Prestationsbaserad självkänsla, kompensatoriska strategier och återhämtning i det gränslösa arbetet

Lukina, Victoria January 2008 (has links)
Gränslöst arbete innebär att ansvaret ligger hos individen och denne själv kan bestämma var, hur och när arbetet ska utföras. Prestationsbaserad självkänsla bidrar till utmattning och sömnsvårigheter och att använda sig av kompensatoriska strategier är ett sätt att hantera gränslösheten. Syftet med studien var att undersöka sambanden mellan prestationsbaserad självkänsla, strategier och återhämtning bland personer med gränslöst arbete. En enkätundersökning genomfördes. Deltagare var 93 män och 47 kvinnor som arbetar på ett privat företag inom säkerhet och utbildning. Variabler testades i multipla regressioner. Resultaten visade att prestationsbaserad självkänsla och användning av kompensatoriska strategier hade en negativ påverkan på återhämtning medan gränslöst arbete hade en positiv effekt. Detta indikerar att gränslöst arbete i sig snarare är en frihet än krav. / Boundaryless work means that the individual himself decides where, how and when to perform his work. Performance-based self-esteem contributes to exhaustion and using compensatory strategies is a way to handle the boundarylessness. The purpose of this study was to examine the relations between performance-based self-esteem, strategies and recovery among people with boundaryless work. A questionnaire study was carried out. The participants were 93 men and 47 women working in a private company with safety and education. Variables were tested in multiple regressions. The results showed that performance-based self-esteem and use of compensatory strategies had negative influence on recovery, while boundaryless work had a positive effect. This indicates that boundaryless work itself is considered more of a freedom than a demand.
70

Experimental and financial investigations into the further development of Damage Avoidance Design

Solberg, Kevin Mark January 2007 (has links)
Multiple experimental and computational tests are performed on precast concrete structures designed for damage avoidance. These structures accommodate non-linear behaviour by rocking at specially detailed connections. Unbonded prestress is employed to provide a restoring force and supplemental devices are used to dissipate energy. Tests are performed on a 30 percent scale bridge pier and an 80 percent scale 3D beam-column joint subassembly. Several detailing strategies are developed and tested. Straight and draped tendon profiles are considered. Supplemental energy dissipation is provided by yielding mild steel devices or lead-extrusion dampers. The lead-extrusion dampers are tested both externally and internally. Detailing at the joint region is refined in an effort to provide a cost-effective and simple solution. A closure pour is considered to simply the construction process. Results indicate it is possible to eliminate virtually all damage at the beam-column joint with minor increased cost from steel armouring. The lead-extrusion damper is shown to be 'resetable', and therefore would not have to be replaced following a seismic event. Two seismic financial risk methodologies are developed to investigate the enhanced performance inherent to ductile jointed structures. A rapid method is introduced which simplifies the intensive computational effort necessary to perform loss studies. A distribution-free computational method is also examined. The methods are demonstrated with a case study of bridge piers designed to different seismic design codes and a bridge designed for damage avoidance. The bridge pier designed for damage avoidance is shown to have an expected annual loss of approximately 25 percent that of the conventional ductile piers.

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