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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.
231

"Special Relationship" v době vlády Harolda Macmillana (1957-1963) / "Special Relationship" in the Era of Harold Macmillan (1957-1963)

Beranová, Monika January 2017 (has links)
This thesis analyzes key moments from the tenures of Harold Macmillan as British Prime Minister and John Fitzgerald Kennedy as President of the United States. The United Kingdom and the United States had a Special Relationship between them, which was based upon their close political cooperation. Macmillan and Kennedy deepend this relation by their personal friendship, which played a major role in the course of finding solutions to the conflicts they had to face in the context of the Cold War, when there was a real possibility of nuclear annihilation. The analysis shows that the Special Relationship in the years 1957-1963 went through several dynamic developments, however it never lost its unique status. Despite initial distrust between the two countries immediately following the Suez Crisis, both politicians always managed to find a compromise solution. Thanks to their friendship and deep personal respect, they managed to always unite, even during times of gravest peril. A typical example of the personal relationship is the Cuban Missile Crisis, when Kennedy kept in touch via telephone with Macmillan and often asked him for advice. By virtue of this contact, Macmillan became one of the President's principal advisors in the course of the crisis. The Special Relationship between the two countries did...
232

Preliminary Design of a High-Enthalpy Hypersonic Wind Tunnel Facility and Analysis of Flow Interactions in a High-Speed Missile Configuration

Joshua Craig Ownbey (10721112) 02 August 2021 (has links)
An approach for designing a high-enthalpy wind tunnel driven by exothermic chemical reactions was developed. Nozzle contours were designed using CONTUR, a program implementing the method of characteristics, to design nozzle contours at various flow conditions. A reacting mixture including nitrous oxide has been identified as the best candidate for providing clean air at high temperatures. The nitrous oxide has a few performance factors that were considered, specifically the combustion of the gas. Initial CFD simulations were performed on the nozzle and test region to validate flow characteristics and possible issues. Initial results show a fairly uniform exit velocity and ability to perform testing. In a second phase of the work, two generic, high-speed missile configurations were explored using numerical simulation. The mean flow was computed on both geometries at 0 and 45 roll and 0, 1, and 10 angle of attack. The computations identified complex flow structures, including three-dimensional shock/boundary-layer interactions, that varied considerably with angle of attack.
233

Evaluation of Missile Guidance and Autopilot through a 6 DOF Simulation Model / Utvärdering av missilstyrlagar och -automat med en 6 DOF simuleringsmodell

Sefastsson, Ulf January 2016 (has links)
Missile guidance and autopilot have been active fields of research since the second world war. There are lots of literature on the subjects, but the bulk of which are confined to overly simplified models, and therefore the publications of the methods applied to more realistic models are scarce. In this report a nonlinear 6 DOF simulation model of a tail-controlled air-to-air missile is considered. Through several assumptions and simplifications a linearized approximation of the plant is obtained, which then is used in the implementation of 5 guidance laws and 2 autopilots. The guidance laws are all based on a linearized collision geometry, and the autopilots are based on model predictive control (MPC). Both autopilots use linear quadratic MPC (LQMPC), and one is more robust to modelling errors than the conventional LQMPC. The guidance laws and autopilots are then evaluated with respect to performance in terms of miss distance in 4 interception scenarios with a moving target. The results show that the in this model the autopilots perform equally well, and that the guidance laws with more information about the target generally exhibit smaller miss distances, but at the cost of a considerably larger flight time for some scenarios. The conclusions are that the simplifying assumptions in the modelling are legitimate and that the challenges of missile control probably does not lie in the guidance or autopilot, but rather in the target tracking. Therefore it is suggested that future work include measurement noise and process disturbances in the model. / Det har forskats kring styrlagarna och styrautomaterna för robotar sedan an-dra världskrigets. Det finns mycket litteratur på områdena, men merparten av de publicerade resultaten behandlar enbart grovt förenklade modeller, och därför är tillgången på publikationer där metoderna applicerats i en mer realistisk modell begränsat. I denna rapport behandlas en olinjär simuleringsmodell av en jaktrobot som styrs med stjärtfenor och har sex frihetsgrader. Genom en rad antaganden och förenklingar erhålls en linjäriserad modell av missilen, vilket sedan används för implementering av fem styrlagar och två styrautomater. Styr-lagarna är alla baserade på en linjäriserad kollisionsgeometri och styrautomaterna är baserade på modellprediktiv styrning (MPC). Båda styrautomaterna använder linjärkvadratisk MPC, där den ena påstås vara mer robust gentemot modellfel. Styrlagarna och -automaterna utvärderas ur ett prestandaperspektiv med fokus på bomavstånd i fyra realistiska genskjutningsscenarier med ett rörligt mål. Resultaten visar att båda styrautomaterna presterar lika bra, och att de styrlagar med mer information om målets position/hastighet/acceleration generellt presterar bättre, men att de för vissa skjutfall får en väsentligt längre flygtid. Slutsatserna är att förenklingarna och antagandena i linjäriseringen är välgrundade, och att utmaningarna i missilstyrning inte ligger i utformning av styrlag/-automat, utan förmodligen i målsökningen. Därför föreslås det slutligen att framtida arbete bl. a. inkluderar mätbrus och störningar.
234

Preliminary Design of a High-Enthalpy Hypersonic Wind Tunnel Facility and Analysis of Flow Interactions in a High-Speed Missile Configuration

Joshua Craig Ownbey (10721112) 29 April 2021 (has links)
An approach for designing a high-enthalpy wind tunnel driven by exothermic chemical reactions was developed. Nozzle contours were designed using CONTUR, a program implementing the method of characteristics, to design nozzle contours at various flow conditions. A reacting mixture including nitrous oxide has been identified as the best candidate for providing clean air at high temperatures. The nitrous oxide has a few performance factors that were considered, specifically the combustion of the gas. Initial CFD simulations were performed on the nozzle and test region to validate flow characteristics and possible issues. Initial results show a fairly uniform exit velocity and ability to perform testing. In a second phase of the work, two generic, high-speed missile configurations were explored using numerical simulation. The mean flow was computed on both geometries at 0 and 45 roll and 0, 1, and 10 angle of attack. The computations identified complex flow structures, including three-dimensional shock/boundary-layer interactions, that varied considerably with angle of attack. <br>
235

Rakety a radary jako bezpečnostní dilema: případ třetího pilíře americké protiraketové obrany ve střední Evropě / Missiles and Radars as Security Dilemma The Case of the Third Pillar of the U.S. Missile Defence in Central Europe

Kantor, Lukáš January 2011 (has links)
The thesis deals with the former Bush's plan of the so-called third pillar of the American missile defense system in Poland and Czech republic. We demonstrate on this topic the value of several key (neo)realist theoretical concepts. Specifically, the exact types and functioning of security dilemmas are analyzed in the framework of American-Russian, American-Iranian and American-Czech/Polish relations. The thesis also illustrates the importance of related modalities of deterrence and shows, which states and how balanced the US. In addition to that, attention is paid to the question whether the "shield" was motivated by defensive realist worries about security or rather by offensive realist struggle for power and gains at the expense of others.
236

Současná americká zahraniční politika ve vztahu k Polsku: vývoj, faktory, tendence / Current U.S. foreign policy towards Poland: key factors, tendencies and developments

Čížková, Tereza January 2013 (has links)
Given the enduring importance of the United States and its superpower status, American foreign policy represents a suitable topic for a detailed analysis. The focusing on Poland and the U.S. foreign policy related to it enables to find factors influencing the process of foreign policy-making and to examine the level of their impact. Selecting Poland can be explained by its great potential and rising importance within European politics as well as the long-lasting partnership between Poland and the United States that has been developed over the years. The characterization of factors influencing the formulation of the U.S. foreign policy enables understanding of tendencies and changes in the U.S. approach towards Poland. Contemporary foreign policy is not solely affected by current developments, but also the historical context and circumstances can have impact on its formulation and current shape. The formation of the American approach towards Poland is not completely isolated from other processes and therefore its final outcome depends on subsequent variables such as general American foreign orientation, the relations with Russia or the course of the general security situation. Dynamic development of events since 2001 shows how these new circumstances can be projected into the shape of foreign policy and...
237

A theory of group decision-making applied to the Bay of Pigs and Cuban Missile Crisis decisions

Slade, Lester Stephen 01 January 1973 (has links)
This study of political decision-making stressing the process of decision-making in a group setting is, in part, a reaction against traditional approaches of political analysis. The study of international relations is overburdened with historical studies of the interaction between states. The classic approach to the study of a given decision by one government affecting another might be called the “rational actor model”. This model treats the state as the entity reaching the decision. The decision itself is seen as behavior that reflects a rational purpose or intent. The central concepts of the model center around the calculated weighing of goals, alternatives, consequences, and choices. The “rational actor model” is the dominant method of current political analysis. I will implicitly contend in this paper that the concept of foreign policy as a rational process of gathering information, setting alternatives, and making decisions is not an adequate tool of understanding. In fact, the “rational actor model” does not make sense out of much political phenomenon. I will directly contend in this paper that a process model of political decision-making provides an adequate and helpful tool for the understanding of political decisions.
238

DEVELOPMENT OF AN OPEN-SOURCE TOOLBOX FOR DESIGN AND ANALYSIS OF ACTIVE DEBRIS REMEDIATION ARCHITECTURES

Joshua David Fitch (16360641) 15 June 2023 (has links)
<p> Orbital Debris is a growing challenge for the Space Industry. The increasing density of derelict objects in high-value orbital regimes is resulting in more conjunction warnings and break-up events with cascading repercussions on active satellites and spacecraft. The recent rapid growth of the commercial space industry, in particular proliferated satellite constellations, has placed orbital debris remediation at the forefront of Space Industry efforts. The need to remove existing debris, combined with a growing demand for active satellite life extension services, has created an emerging market for space logistics, in particular spacecraft capable of rendezvous and docking, orbital refueling, debris deorbiting, or object relocation. This market has seen numerous companies emerge with multi-purpose on-orbit servicing platforms. This ecosystem poses technological, economical, and policy questions to decision-makers looking to acquire platforms or invest in technologies and requires a System-of-Systems approach to determine mission and system concepts of merit. An open-source modeling, analysis, and simulation software toolbox has been developed which enables rapid early-stage analysis and design of diverse fleets of on-orbit servicing platforms, with a specific emphasis on active debris removal applications. The toolbox provides fetching and processing of real-time orbital catalog data, clustering and scoring of high-value debris targets, flexible and efficient multi-vehicle multi-objective time-varying routing optimization, and fleet-level lifecycle cost estimation. The toolbox is applied to a diverse sample of promising commercial platforms to enable government decision-makers to make sound investment and acquisition decisions to support the development of ADR technologies, missions, and companies. </p>
239

MULTIPLE SIGNALS OF OPPORTUNITY FOR LAND REMOTE SENSING

Seho Kim (8820074) 27 July 2023 (has links)
<p>Multiple Signals of Opportunity (multi-SoOp) across different frequencies and polarizations</p> <p>offer a potential breakthrough for remote sensing of root-zone soil moisture (RZSM). Deeper penetration depths of existing communication transmissions in the frequency ranges of 137–138, 240–270, and 360–380 MHz enable the estimation of RZSM by complementing global navigation satellite system reflectometry (GNSS-R) in L-band. The small form factor of the multi-SoOp observatory allows for high spatiotemporal coverage of RSZM by a satellite constellation in a cost-effective manner. This study aims to develop models and tools to define mission requirements for various system parameters that affect observation accuracy and coverage, for the advancement of spaceborne multi-SoOp remote sensing. These parameters include frequency and polarization combinations, observation error, inter-frequency temporal coincidence, and configuration of the satellite constellation. We present the development of a retrieval algorithm and the sensitivity analysis of retrieval accuracy. The retrieval algorithm was evaluated using synthetic observations generated from multiyear time series of in-situ soil moisture (SM) and satellite-based vegetation data. The combined use of both high and low frequencies improves retrieval accuracy by limiting uncertainties from vegetation and surface SM and providing sensitivity to deeper layers. A bivariate model, derived from the sensitivity analysis, facilitates error prediction for future science missions. We introduce a framework for tradespace exploration of the multi-SoOp satellite constellation. A constellation design study indicates that a Walker constellation comprising 24 satellites with 3 orbital planes at 500 km and 50° inclination optimizes the coverage and mission cost under mission requirements. A tower-based field experiment validated the performance of a prototype antenna for multi-SoOp using the interference pattern technique. More field experiments with improved instruments are required to further advance the multi-SoOp technique.</p>
240

A Customer Value Assessment Process (CVAP) for Ballistic Missile Defense

Hernandez, Alex 01 June 2015 (has links) (PDF)
A systematic customer value assessment process (CVAP) was developed to give system engineering teams the capability to qualitatively and quantitatively assess customer values. It also provides processes and techniques used to create and identify alternatives, evaluate alternatives in terms of effectiveness, cost, and risk. The ultimate goal is to provide customers (or decision makers) with objective and traceable procurement recommendations. The creation of CVAP was driven by an industry need to provide ballistic missile defense (BMD) customers with a value proposition of contractors’ BMD systems. The information that outputs from CVAP can be used to guide BMD contractors in formulating a value proposition, which is used to steer customers to procure their BMD system(s) instead of competing system(s). The outputs from CVAP also illuminate areas where systems can be improved to stay relevant with customer values by identifying capability gaps. CVAP incorporates proven approaches and techniques appropriate for military applications. However, CVAP is adaptable and may be applied to business, engineering, and even personal every-day decision problems and opportunities. CVAP is based on the systems decision process (SDP) developed by Gregory S. Parnell and other systems engineering faculty at the Unites States Military Academy (USMA). SDP combines Value-Focused Thinking (VFT) decision analysis philosophy with Multi-Objective Decision Analysis (MODA) quantitative analysis of alternatives. CVAP improves SDP’s qualitative value model by implementing Quality Function Deployment (QFD), solution design implements creative problem solving techniques, and the qualitative value model by adding cost analysis and risk assessment processes practiced by the U.S DoD and industry. CVAP and SDP fundamentally differ from other decision making approaches, like the Analytic Hierarchy Process (AHP) and the Technique for Order of Preference by Similarity to Ideal Solution (TOPSIS), by distinctly separating the value/utility function assessment process with the ranking of alternatives. This explicit value assessment allows for straightforward traceability of the specific factors that influence decisions, which illuminates the tradeoffs involved in making decisions with multiple objectives. CVAP is intended to be a decision support tool with the ultimate purpose of helping decision makers attain the best solution and understanding the differences between the alternatives. CVAP does not include any processes for implementation of the alternative that the customer selects. CVAP is applied to ballistic missile defense (BMD) to give contractors ideas on how to use it. An introduction of BMD, unique BMD challenges, and how CVAP can improve the BMD decision making process is presented. Each phase of CVAP is applied to the BMD decision environment. CVAP is applied to a fictitious BMD example.

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