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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.
1

Geometric reaction forces in billiards

Sinclair, E. C. January 1995 (has links)
No description available.
2

Human Dimensions of Young Forest Conservation Programs: Effects of Outreach, Post-Program Management, and a Coupled Systems Perspective

Lutter, Seth Hendrik 13 August 2018 (has links)
Achieving long-term conservation gains through the framework of conservation incentive programs requires an understanding of both the ecological and social components of these programs. Landowner program experiences and management decisions after program participation are important for long-term conservation, but these aspects of conservation programs are not well understood. To address this research gap related to conservation program participation, this thesis investigates Natural Resources Conservation Service programs that provide private landowners with financial and technical assistance to manage for young forest habitat in the eastern United States. We conducted a telephone survey to investigate private landowner experiences during and after participation in these NRCS conservation programs. Coordinating with biologists monitoring managed properties for birds, we assessed how in-person outreach and mailed monitoring results influenced landowners. Next, we evaluated how landowner motivations, resources, and cognitions were related to post-program young forest management intentions. Finally, we applied a coupled human and natural systems lens to investigate the linkage between wildlife outcomes, landowner perceptions, and continued young forest management. Our results demonstrate how in-person outreach can shape positive conservation experiences and increasing landowner trust in resource agencies. We also demonstrate the importance of both social and environmental factors for influencing landowner decision-making after conservation program participation. We detail the applications of this research for conservation agencies and professionals who work with private landowners. / Master of Science / The decline of young forest habitat and associated wildlife species is a major conservation issue in the eastern United States. Since 2011, Natural Resources Conservation Service conservation programs have provided hundreds of private landowners with financial and technical assistance to create and maintain young forest habitat. Landowner program experiences and management decisions after program participation are important for long-term conservation, but information is limited on these aspects of NRCS young forest programs. In response, we conducted a telephone survey to investigate private landowner experiences during and after participation in these conservation programs. Coordinating with biologists monitoring managed properties for birds, we assessed how in-person outreach and mailed monitoring results influenced landowners. Next, we evaluated how landowner motivations, resources, and cognitions were related to post-program young forest management intentions. Finally, we examined how landowners observed and interpreted wildlife outcomes of young forest management and how these perceptions were related to habitat management after program participation. Our results highlight the importance of in-person outreach for shaping positive conservation experiences and increasing landowner trust in resource agencies. We also demonstrate the importance of both social and environmental factors for influencing landowner decision-making after conservation program participation. We detail the applications of this research for conservation agencies and professionals who work with private landowners.
3

Security Analysis of Interdependent Critical Infrastructures: Power, Cyber and Gas

January 2018 (has links)
abstract: Our daily life is becoming more and more reliant on services provided by the infrastructures power, gas , communication networks. Ensuring the security of these infrastructures is of utmost importance. This task becomes ever more challenging as the inter-dependence among these infrastructures grows and a security breach in one infrastructure can spill over to the others. The implication is that the security practices/ analysis recommended for these infrastructures should be done in coordination. This thesis, focusing on the power grid, explores strategies to secure the system that look into the coupling of the power grid to the cyber infrastructure, used to manage and control it, and to the gas grid, that supplies an increasing amount of reserves to overcome contingencies. The first part (Part I) of the thesis, including chapters 2 through 4, focuses on the coupling of the power and the cyber infrastructure that is used for its control and operations. The goal is to detect malicious attacks gaining information about the operation of the power grid to later attack the system. In chapter 2, we propose a hierarchical architecture that correlates the analysis of high resolution Micro-Phasor Measurement Unit (microPMU) data and traffic analysis on the Supervisory Control and Data Acquisition (SCADA) packets, to infer the security status of the grid and detect the presence of possible intruders. An essential part of this architecture is tied to the analysis on the microPMU data. In chapter 3 we establish a set of anomaly detection rules on microPMU data that flag "abnormal behavior". A placement strategy of microPMU sensors is also proposed to maximize the sensitivity in detecting anomalies. In chapter 4, we focus on developing rules that can localize the source of an events using microPMU to further check whether a cyber attack is causing the anomaly, by correlating SCADA traffic with the microPMU data analysis results. The thread that unies the data analysis in this chapter is the fact that decision are made without fully estimating the state of the system; on the contrary, decisions are made using a set of physical measurements that falls short by orders of magnitude to meet the needs for observability. More specifically, in the first part of this chapter (sections 4.1- 4.2), using microPMU data in the substation, methodologies for online identification of the source Thevenin parameters are presented. This methodology is used to identify reconnaissance activity on the normally-open switches in the substation, initiated by attackers to gauge its controllability over the cyber network. The applications of this methodology in monitoring the voltage stability of the grid is also discussed. In the second part of this chapter (sections 4.3-4.5), we investigate the localization of faults. Since the number of PMU sensors available to carry out the inference is insufficient to ensure observability, the problem can be viewed as that of under-sampling a "graph signal"; the analysis leads to a PMU placement strategy that can achieve the highest resolution in localizing the fault, for a given number of sensors. In both cases, the results of the analysis are leveraged in the detection of cyber-physical attacks, where microPMU data and relevant SCADA network traffic information are compared to determine if a network breach has affected the integrity of the system information and/or operations. In second part of this thesis (Part II), the security analysis considers the adequacy and reliability of schedules for the gas and power network. The motivation for scheduling jointly supply in gas and power networks is motivated by the increasing reliance of power grids on natural gas generators (and, indirectly, on gas pipelines) as providing critical reserves. Chapter 5 focuses on unveiling the challenges and providing solution to this problem. / Dissertation/Thesis / Doctoral Dissertation Electrical Engineering 2018
4

A graph-theoretic approach to the construction of Lyapunov functions for coupled systems on networks

Shuai, Zhisheng 11 1900 (has links)
For coupled systems of differential equations on networks, a graph-theoretic approach to the construction of Lyapunov functions is systematically developed in this thesis. Kirchhoffs Matrix-Tree Theorem in graph theory plays an essential role in the approachs development. The approach is successfully applied to several coupled systems well-known in the literature to demonstrate its applicability and effectiveness. / Applied Mathematics
5

Design and Control of Products Including Parts with Impacts

Jerrelind, Jenny January 2004 (has links)
Today's product development process should be rapid andcost-efficient, and should result in innovative and reliableproducts. A crucial factor is the dynamic behaviour of theproduct. This thesis focuses on theoretical, numerical andexperimental approaches to achieve a comprehensiveunderstanding of dynamical phenomena occurring in nonlinearproducts, especially in products with parts that includeimpacts. The aim is to show the usefulness of nonlineartheories to better understand and optimise the dynamicbehaviour of products and thereby account for nonlinearphenomena already in the product development process. This is achieved through an investigation of researchefforts in the field of nonlinear dynamics; identification ofimportant research directions; a study on the effect ofcouplings between nonlinear parts; a detailed study on thedynamic behaviour of a product component; investigations oflow-cost strategies for controlling the dynamics of a nonlinearsystem; and the design and implementation of experimentalset-ups of two studied products. The investigation of research efforts shows that nonlinearparts are frequently included in products. Most common areparts that are nonlinear due to impacts and friction. Twoimportant areas are identified; to study coupling effectsbetween nonlinear subsystems and to study how nonlinearanalysis can be used to improve existing designs. Considering the studied products; a pantograph on a trainand a Braille printer, it can be concluded that thecharacteristics of a part can largely affect the dynamicbehaviour of the product. Typical nonlinear behaviour, such ascoexisting solutions and irregular motions, do occur. Theanalysis of the pan- tograph motion shows important aspects toconsider in the modelling process; coupling effects. In thecase of the Braille printer it is shown possible to create alow-cost control, by taking advantage of an existingdiscontinuity, to achieve a desired motion. Altogether, this work contributes to improved understandingof the be- haviour of nonlinear parts in products, especiallythose including impacts, pro- viding greater knowledge aboutaspects to consider in the design process. Keywords:Nonlinear Dynamics, Impacts, Discontinuities,Subsystems, Chaos, Irregular Behaviour, Printer Dynamics,Suspensions, Coupled Systems, Control. / QC 20100621
6

A graph-theoretic approach to the construction of Lyapunov functions for coupled systems on networks

Shuai, Zhisheng Unknown Date
No description available.
7

Exploring middle managers sensemaking processes during the adoption and practice of sustainability strategies in organisations

Aryee, Benonia January 2016 (has links)
The thesis explores middle managers sensemaking processes of a University’s social responsibility and sustainability (SRS) strategy during a period of change. Overall the thesis establishes links between middle managers simultaneous sensemaking processes, dynamics of loosely coupled organizational contexts and organizational responses to unexpected outcomes as they impact strategy creation processes in organisations. Three main issues evolve. Firstly, middle managers in loosely coupled organisations consist of two different sets (administrators and academics). Based on their nature of work in particular, administrators and academics select different sets of dominant and subtle sensemaking frames to make sense of organizational strategies. Generally, while administrators select sensemaking frames which emanate from existing strategic processes, academics select autonomous cues which exist outside strategic processes. Administrators and academics sensemaking processes are therefore not a single level or consecutive processes as typically researched, but rather occur as simultaneous sensemaking processes. Six dominant simultaneous sensemaking frames are identified and described. Secondly, the thesis examines less explored aspects of debates on loosely coupled systems. It investigates specific patterns of coupledness in middle managers strategic work and relationships. It identified and described patterns of administrative work which are tightly coupled and patterns in academic work which are loosely coupled. Thirdly, distinct links are identified between middle managers simultaneous sensemaking processes and unexpected strategy outcomes. This further led to exploring how organizations respond to unexpected sustainability initiatives, especially in light of integrating them into already existing strategy outcomes. Three integration strategies are identified and described.
8

Improved Reduced Order Modeling Strategies for Coupled and Parametric Systems

Sutton, Daniel 25 August 2005 (has links)
This thesis uses Proper Orthogonal Decomposition to model parametric and coupled systems. First, Proper Orthogonal Decomposition and its properties are introduced as well as how to numerically compute the decomposition. Next, a test case was used to show how well POD can be used to simulate and control a system. Finally, techniques for modeling a parametric system over a given range and a coupled system split into subdomains were explored, as well as numerical results. / Master of Science
9

Avvikelsens mekanismer : Observationer av projekt i praktiken / Mechanisms of deviations : Observations of projects in practice

Hällgren, Markus January 2009 (has links)
Bakgrund I det närmaste alla organisationer strävar efter att använda sina resurser så effektivt som möjligt. Vad som dock inte diskuterats i någon större utsträckning är att den starkt kopplade komplexa organisationen inte klarar av att bemöta ens den minsta avvikelsen utan att ägna den direkt uppmärksamhet. Den övergripande frågan är därför Hur hanteras avvikelser i starkt kopplade projekt? Det teoretiska ramverket är först och främst projektlitteratur men ramverket vidgas sedermera till att omfatta praktikansatslitteratur samt Weicks (1976) ”Loosely coupled systems”. Metod Givet ansatsen faller det sig naturligt att göra en fallstudie med observationer som huvudsaklig metod. Utöver tolv veckors observationer förlitar jag mig på 57 intervjuer och mängder av dokument. En organisation, två projektgrupper och 118 avvikelser observerades totalt under perioden. De data som samlades in analyserades med hjälp av dataprogrammet Nvivo. Resultat Analysen är uppdelad i tre integrerade kapitel. Det första kapitlet diskuterar avvikelser som företeelse och definierar begreppet närmare. En avvikelse definieras som en händelse som kräver såväl identitet som handlingskraft. Det andra analyskapitlet analyserar praktiken närmare. Allt som allt observerades 29 praktiker vilka kunde grupperas i åtta praktikmönster. Praktikmönstren kunde sedermera inordnas i två distinkta löskopplingsmönster i en teoretiskt underbyggd och empiriskt styrkt figur. Figuren och följaktligen praktikmönstren beskriver hur avvikelsen görs löst kopplad. Det tredje analyskapitlet diskuterar fem mekanismer som följer av med de löst kopplade avvikelserna. Dessa fem mekanismer kan sedermera betonas och utnyttjas av projektledaren. Slutsatser Slutsatserna följer två spår. Det ena spåret fokuserar på projekt i allmänhet och projektledning i synnerhet. Slutsatsen som kan dras där är att det finns en inneboende osäkerhet i projekt som kan utnyttjas för att hantera avvikelser. Alla avvikelser har inte stora konsekvenser men de besitter vissa gemensamma egenskaper. Det andra spåret är ett bidrag till teorin om löst kopplade system. Länge har en processuell och praktikbaserad studie saknats. Genom att undersöka löskopplingsprocesser i ljuset av en praktikansats har jag visat hur löskopplingsprocesser ser ut.
10

Supplemental Educational Services in an Urban Local Education Agency: Case Study of District Implementation

January 2011 (has links)
abstract: The purpose of this study was to explore features of Supplemental Educational Services (SES) implementation at the district level. In the study beliefs, goals, and actions of district office administrators were analyzed against the backdrop of changing federal guidelines and challenges faced by SES implementers across Arizona. The case study focuses on implementation in the 2007-2008, 2008-2009, and 2009-2010 school years. The study uses the 2005 and 2009 Department of Education guidelines, survey responses from Arizona district and school implementers, as well as documents and interviews from an urban Arizona case district. The study separates the implementation activities into task areas, which are analyzed separately. Using a loose coupling perspective, the separate task areas are furthered used as coupling domains and represented in social network graphs. Results show that the case district personnel were highly focused on their primary role, maintaining district compliance with federal guidelines. The district personnel employed several changes over the case study period to centralize their control of SES operations within district. The employment and training of site level coordinators was the most impactful of the strategies. As boundary spanners, the coordinators allowed greater access to information, oversight, and influence at the site level. Despite the growing capacity and earnest efforts of the district personnel, the case district was still very far from being able to measure or assess the impact of SES on student achievement. Centralization in the scholastic task areas was relatively low, and had marginal changes over the case study period. Years into the program, there was still no avenue to accurately gauge the effectiveness. As the district personnel were chiefly concerned with compliance, they had suspended judgment on the program and focused primarily on improving their processes. / Dissertation/Thesis / Ph.D. Educational Leadership and Policy Studies 2011

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