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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.
931

The Spatial 2:1 Resonant Orbits in Multibody Models: Analysis and Applications

Andrew Joseph Binder (18848701) 24 June 2024 (has links)
<p dir="ltr">Within the aerospace community in recent years, there has been a marked increase in interest in cislunar space. To this end, the study of the dynamics of this regime has flourished in both quantity and quality in recent years, spearheaded by the use of simplified dynamical models to gain insight into the dynamics and to generate viable mission concepts. The most popular and simple of these models, the Circular Restricted Three-Body Problem, has been thoroughly explored to meet these goals (even well-prior to the recent spike in interest). Much work has been done investigating periodic orbits within these models, and similarly has been performed on non-periodic transfers into periodic orbits. Studied less is the superposition of these two concepts, or using periodic orbits as a way to transit, for example, cislunar space. In this thesis, the development of periodic orbits amenable to transiting is accomplished. Beginning from periodic orbit families already present in the literature, this research finds a novel and useful family of periodic orbits, here dubbed the spatial 2:1-resonant orbit family. Within this newly-discovered family, multitudes of qualitative behaviors interesting to the astrodynamics community are found. Many family members seem accommadating to a diverse set of mission profiles, from purely-unstable family members best suited to use as transfers, to marginally stable ones best suited to longer-term use. This family as a whole is analyzed and catalogued with thorough descriptions of behavior, both quantitative and qualitative. While the Circular Restricted Three-Body Problem serves as an excellent starting point for analysis, trajectories found there must be generalized to higher-fidelity modeling. In this spirit, this thesis also focuses on demonstrating such generalization and putting it into practice using the more sophisticated Elliptic-Restricted Three-Body Problem. Documentation of the numerical tools necessary and helpful in accomplishing this generalization is included in this work. Prototypically, the truly 2:1 sidereally-resonant unstable member of the 2:1 family is transitioned into the elliptic problem, as is a nearly-stable L2 Halo orbit family member. This new trajectory is paired with a more classically-present example to show the validity of the methodology. To aid this analysis, symmetries present within the elliptic model are also explored and explained. With this analysis completed, this orbit family is demonstrated to be both interesting and useful, when considered under even more realistic modelling. Further work to mature this novel family of orbits is merited, both for use as the fundamental building block for transfers and for use for more-permanent habitation. More broadly, this work aims to achieve a further proliferation of the merger between transfer and orbit, concepts which seem distinct at first, but deserve more gradual consideration as different flavors of the same idea.</p>
932

[pt] RESOLVENDO OS PROBLEMAS DETERMINÍSTICO E ESTOCÁSTICO DE ESCALONAMENTO DE EMBARCAÇÕES DO TIPO PIPE- LAYING SUPPORT VESSEL / [en] SOLVING THE DETERMINISTIC AND STOCHASTIC PIPE-LAYING SUPPORT VESSEL SCHEDULING PROBLEM

VICTOR ABU-MARRUL CARNEIRO DA CUNHA 26 July 2021 (has links)
[pt] Empresas de exploração de petróleo e gás offshore frequentemente precisam lidar com problemas relacionados ao uso eficiente de seus recursos. Neste trabalho, abordamos um problema de programação de navios associado à logística offshore de petróleo e gás – O Problema de Programação de Embarcações do tipo Pipe-Laying support Vessel (PLSVSP). Essas embarcações são especialmente projetadas para realizar conexões de dutos entre poços de petróleo submarinos e plataformas de produção. A conexão de dutos é a última etapa a ser executada para permitir a drenagem do óleo e iniciar a produção em um poço. No PLSVSP, o objetivo é antecipar a conclusão de poços mais produtivos. O problema pode ser visto como uma variante de um problema de programação de lotes com máquinas paralelas idênticas e tempos de configuração não antecipados por família para minimizar o total weighted completion time. Nessa analogia, embarcações são as máquinas, poços são as tarefas e lotes são as viagens executadas por PLSVs, definindo quais poços devem ser conectados a cada saída do porto. Foram desenvolvidas diversas abordagens de otimização para resolver as variantes determinística e estocástica do problema. Para a variante determinística, desenvolvemos métodos híbridos e uma metaheurística capazes de melhorar as soluções desenvolvidas por formulações MIP puras e lidar com o PLSVSP. Para a variante estocástica, foi desenvolvida uma simheurística utilizando simulação de Monte Carlo incorporada, considerando incertezas nas durações das conexões e nas datas de chegada dos oleodutos no porto. Os resultados mostram uma melhora significativa no custo das soluções quando lidam com incertezas em comparação com soluções geradas por um método determinístico. O uso da simulação em uma estrutura metaheurística mostrou-se uma abordagem promissora, capaz de lidar com o problema estocástico, com pouco esforço computacional extra necessário. / [en] Offshore oil and gas exploration companies frequently need to deal with problems related to the efficient use of their resources. In this work, we address a ship scheduling problem associated with offshore oil and gas logistics – The Pipe Laying Support Vessel Scheduling Problem (PLSVSP). These vessels are specially designed to perform pipeline connections between sub-sea oil wells and production platforms. The connections are the last step to be performed to allow the oil draining, starting production in a well. The PLSVSP objective is to anticipate the completion of the most productive wells. The problem can be seen as a variant of a batch scheduling problem with identical parallel machines and non-anticipatory family setup times to minimize the total weighted completion time. In this analogy, vessels are machines, wells are jobs, and batches are voyages executed by PLSVs, defining which wells to connect each time it leaves the port. We developed several optimization approaches to solve the deterministic and stochastic variants of the problem. For the deterministic problem, we developed hybrid methods and a metaheuristic that outperformed the pure MIP formulations, being practical to deal with the PLSVSP. A simheuristic using embedded Monte Carlo simulation was developed for the stochastic variant of the problem, considering uncertainties in the connection duration and the arrival dates of pipelines at the port. The results show a significant improvement in the solutions dealing with uncertainties compared to solutions generated by a deterministic method. The use of simulation within a metaheuristic framework proved to be a promising approach, being able to deal with the stochastic problem, with little extra computational effort required.
933

Scale Invariant Equations and Their Modified EM Algorithm for Estimating a Two-Component Mixture Model

Ukenazor, Ifeanyichukwu Valentine 07 1900 (has links)
In this work, we propose a novel two-component mixture model: the first component is the three-parameter generalized Gaussian distribution (GGD), and the second is a new three-parameter family of positive densities on the real line. The novelty of our mixture model is that we allow the two components to have totally different parametric families of distributions with asymmetric tails of the mixture density. We extend the scale invariant variable fractional moments (SIVFM) method proposed by Song for the GGD to the parameter estimation of our mixture model. We show that the SIVFM population and sample equations for the second component share very similar desirable global properties such as convexity and unique global roots as those for the GGD given in earlier research. The two-component mixing of these properties make the SIVFM mixture population and estimation equations well-behaved resulting in easy to compute estimators without the issue with starting values. The asymptotic results such as consistency and limiting distribution of the estimators are presented. Furthermore, SIVFM estimators can also serve as a consistent initial estimator for the EM algorithm leading to improved accuracy of the EM algorithm. These algorithms are applied to the analysis of the average amount of precipitation (rainfall) for each of 70 United States (and Puerto Rican) cities clearly demonstrating the bimodal distribution of the estimated mixture density.
934

Resource Allocation on Networks: Nested Event Tree Optimization, Network Interdiction, and Game Theoretic Methods

Lunday, Brian Joseph 08 April 2010 (has links)
This dissertation addresses five fundamental resource allocation problems on networks, all of which have applications to support Homeland Security or industry challenges. In the first application, we model and solve the strategic problem of minimizing the expected loss inflicted by a hostile terrorist organization. An appropriate allocation of certain capability-related, intent-related, vulnerability-related, and consequence-related resources is used to reduce the probabilities of success in the respective attack-related actions, and to ameliorate losses in case of a successful attack. Given the disparate nature of prioritizing capital and material investments by federal, state, local, and private agencies to combat terrorism, our model and accompanying solution procedure represent an innovative, comprehensive, and quantitative approach to coordinate resource allocations from various agencies across the breadth of domains that deal with preventing attacks and mitigating their consequences. Adopting a nested event tree optimization framework, we present a novel formulation for the problem as a specially structured nonconvex factorable program, and develop two branch-and-bound schemes based respectively on utilizing a convex nonlinear relaxation and a linear outer-approximation, both of which are proven to converge to a global optimal solution. We also investigate a fundamental special-case variant for each of these schemes, and design an alternative direct mixed-integer programming model representation for this scenario. Several range reduction, partitioning, and branching strategies are proposed, and extensive computational results are presented to study the efficacy of different compositions of these algorithmic ingredients, including comparisons with the commercial software BARON. The developed set of algorithmic implementation strategies and enhancements are shown to outperform BARON over a set of simulated test instances, where the best proposed methodology produces an average optimality gap of 0.35% (compared to 4.29% for BARON) and reduces the required computational effort by a factor of 33. A sensitivity analysis is also conducted to explore the effect of certain key model parameters, whereupon we demonstrate that the prescribed algorithm can attain significantly tighter optimality gaps with only a near-linear corresponding increase in computational effort. In addition to enabling effective comprehensive resource allocations, this research permits coordinating agencies to conduct quantitative what-if studies on the impact of alternative resourcing priorities. The second application is motivated by the author's experience with the U.S. Army during a tour in Iraq, during which combined operations involving U.S. Army, Iraqi Army, and Iraqi Police forces sought to interdict the transport of selected materials used for the manufacture of specialized types of Improvised Explosive Devices, as well as to interdict the distribution of assembled devices to operatives in the field. In this application, we model and solve the problem of minimizing the maximum flow through a network from a given source node to a terminus node, integrating different forms of superadditive synergy with respect to the effect of resources applied to the arcs in the network. Herein, the superadditive synergy reflects the additional effectiveness of forces conducting combined operations, vis-à-vis unilateral efforts. We examine linear, concave, and general nonconcave superadditive synergistic relationships between resources, and accordingly develop and test effective solution procedures for the underlying nonlinear programs. For the linear case, we formulate an alternative model representation via Fourier-Motzkin elimination that reduces average computational effort by over 40% on a set of randomly generated test instances. This test is followed by extensive analyses of instance parameters to determine their effect on the levels of synergy attained using different specified metrics. For the case of concave synergy relationships, which yields a convex program, we design an inner-linearization procedure that attains solutions on average within 3% of optimality with a reduction in computational effort by a factor of 18 in comparison with the commercial codes SBB and BARON for small- and medium-sized problems; and outperforms these softwares on large-sized problems, where both solvers failed to attain an optimal solution (and often failed to detect a feasible solution) within 1800 CPU seconds. Examining a general nonlinear synergy relationship, we develop solution methods based on outer-linearizations, inner-linearizations, and mixed-integer approximations, and compare these against the commercial software BARON. Considering increased granularities for the outer-linearization and mixed-integer approximations, as well as different implementation variants for both these approaches, we conduct extensive computational experiments to reveal that, whereas both these techniques perform comparably with respect to BARON on small-sized problems, they significantly improve upon the performance for medium- and large-sized problems. Our superlative procedure reduces the computational effort by a factor of 461 for the subset of test problems for which the commercial global optimization software BARON could identify a feasible solution, while also achieving solutions of objective value 0.20% better than BARON. The third application is likewise motivated by the author's military experience in Iraq, both from several instances involving coalition forces attempting to interdict the transport of a kidnapping victim by a sectarian militia as well as, from the opposite perspective, instances involving coalition forces transporting detainees between interment facilities. For this application, we examine the network interdiction problem of minimizing the maximum probability of evasion by an entity traversing a network from a given source to a designated terminus, while incorporating novel forms of superadditive synergy between resources applied to arcs in the network. Our formulations examine either linear or concave (nonlinear) synergy relationships. Conformant with military strategies that frequently involve a combination of overt and covert operations to achieve an operational objective, we also propose an alternative model for sequential overt and covert deployment of subsets of interdiction resources, and conduct theoretical as well as empirical comparative analyses between models for purely overt (with or without synergy) and composite overt-covert strategies to provide insights into absolute and relative threshold criteria for recommended resource utilization. In contrast to existing static models, in a fourth application, we present a novel dynamic network interdiction model that improves realism by accounting for interactions between an interdictor deploying resources on arcs in a digraph and an evader traversing the network from a designated source to a known terminus, wherein the agents may modify strategies in selected subsequent periods according to respective decision and implementation cycles. We further enhance the realism of our model by considering a multi-component objective function, wherein the interdictor seeks to minimize the maximum value of a regret function that consists of the evader's net flow from the source to the terminus; the interdictor's procurement, deployment, and redeployment costs; and penalties incurred by the evader for misperceptions as to the interdicted state of the network. For the resulting minimax model, we use duality to develop a reformulation that facilitates a direct solution procedure using the commercial software BARON, and examine certain related stability and convergence issues. We demonstrate cases for convergence to a stable equilibrium of strategies for problem structures having a unique solution to minimize the maximum evader flow, as well as convergence to a region of bounded oscillation for structures yielding alternative interdictor strategies that minimize the maximum evader flow. We also provide insights into the computational performance of BARON for these two problem structures, yielding useful guidelines for other research involving similar non-convex optimization problems. For the fifth application, we examine the problem of apportioning railcars to car manufacturers and railroads participating in a pooling agreement for shipping automobiles, given a dynamically determined total fleet size. This study is motivated by the existence of such a consortium of automobile manufacturers and railroads, for which the collaborative fleet sizing and efforts to equitably allocate railcars amongst the participants are currently orchestrated by the \textit{TTX Company} in Chicago, Illinois. In our study, we first demonstrate potential inequities in the industry standard resulting either from failing to address disconnected transportation network components separately, or from utilizing the current manufacturer allocation technique that is based on average nodal empty transit time estimates. We next propose and illustrate four alternative schemes to apportion railcars to manufacturers, respectively based on total transit time that accounts for queuing; two marginal cost-induced methods; and a Shapley value approach. We also provide a game-theoretic insight into the existing procedure for apportioning railcars to railroads, and develop an alternative railroad allocation scheme based on capital plus operating costs. Extensive computational results are presented for the ten combinations of current and proposed allocation techniques for automobile manufacturers and railroads, using realistic instances derived from representative data of the current business environment. We conclude with recommendations for adopting an appropriate apportionment methodology for implementation by the industry. / Ph. D.
935

Integrated Aircraft Fleeting, Routing, and Crew Pairing Models and Algorithms for the Airline Industry

Shao, Shengzhi 23 January 2013 (has links)
The air transportation market has been growing steadily for the past three decades since the airline deregulation in 1978. With competition also becoming more intense, airline companies have been trying to enhance their market shares and profit margins by composing favorable flight schedules and by efficiently allocating their resources of aircraft and crews so as to reduce operational costs. In practice, this is achieved based on demand forecasts and resource availabilities through a structured airline scheduling process that is comprised of four decision stages: schedule planning, fleet assignment, aircraft routing, and crew scheduling. The outputs of this process are flight schedules along with associated assignments of aircraft and crews that maximize the total expected profit. Traditionally, airlines deal with these four operational scheduling stages in a sequential manner. However, there exist obvious interdependencies among these stages so that restrictive solutions from preceding stages are likely to limit the scope of decisions for succeeding stages, thus leading to suboptimal results and even infeasibilities. To overcome this drawback, we first study the aircraft routing problem, and develop some novel modeling foundations based on which we construct and analyze an integrated model that incorporates fleet assignment, aircraft routing, and crew pairing within a single framework. Given a set of flights to be covered by a specific fleet type, the aircraft routing problem (ARP) determines a flight sequence for each individual aircraft in this fleet, while incorporating specific considerations of minimum turn-time and maintenance checks, as well as restrictions on the total accumulated flying time, the total number of takeoffs, and the total number of days between two consecutive maintenance operations. This stage is significant to airline companies as it directly assigns routes and maintenance breaks for each aircraft in service. Most approaches for solving this problem adopt set partitioning formulations that include exponentially many variables, thus requiring the design of specialized column generation or branch-and-price algorithms. In this dissertation, however, we present a novel compact polynomially sized representation for the ARP, which is then linearized and lifted using the Reformulation-Linearization Technique (RLT). The resulting formulation remains polynomial in size, and we show that it can be solved very efficiently by commercial software without complicated algorithmic implementations. Our numerical experiments using real data obtained from United Airlines demonstrate significant savings in computational effort; for example, for a daily network involving 344 flights, our approach required only about 10 CPU seconds for deriving an optimal solution. We next extend Model ARP to incorporate its preceding and succeeding decision stages, i.e., fleet assignment and crew pairing, within an integrated framework. We formulate a suitable representation for the integrated fleeting, routing, and crew pairing problem (FRC), which accommodates a set of fleet types in a compact manner similar to that used for constructing the aforementioned aircraft routing model, and we generate eligible crew pairings on-the-fly within a set partitioning framework. Furthermore, to better represent industrial practice, we incorporate itinerary-based passenger demands for different fare-classes. The large size of the resulting model obviates a direct solution using off-the-shelf software; hence, we design a solution approach based on Benders decomposition and column generation using several acceleration techniques along with a branch-and-price heuristic for effectively deriving a solution to this model. In order to demonstrate the efficacy of the proposed model and solution approach and to provide insights for the airline industry, we generated several test instances using historical data obtained from United Airlines. Computational results reveal that the massively-sized integrated model can be effectively solved in reasonable times ranging from several minutes to about ten hours, depending on the size and structure of the instance. Moreover, our benchmark results demonstrate an average of 2.73% improvement in total profit (which translates to about 43 million dollars per year) over a partially integrated approach that combines the fleeting and routing decisions, but solves the crew pairing problem sequentially. This improvement is observed to accrue due to the fact that the fully integrated model effectively explores alternative fleet assignment decisions that better utilize available resources and yield significantly lower crew costs. / Ph. D.
936

Development and testing of mycoinsecticides based on submerged spores and aerial conidia of the entomopathogenic fungi Beauveria bassiana and Metarhizium anisopliae (Deuteromycotina: Hyphomycetes) for control of locusts, grasshoppers and storage pests / Mycoinsecticides for pest control / Biologische Schädlingsbekämpfung / Mykoinsektiziden für Schädlingsbekämpfung

Kassa, Adane 14 July 2003 (has links)
No description available.
937

Verification of the local similarity theory above forests / Verifikation lokala likhetsteori över skogen

Hubmann, Yasmin January 2021 (has links)
In this study, the local similarity theory functions were calculated with two different approaches and on the other hand the mean hub height wind speed was compared with the rotor equivalent wind speed. Both calculations are based on two independent data-sets from measurement campaigns Hornamossen and Ryningsnäs which were conducted in the south of Sweden between May 2015 and June 2017, and November 2010 and February 2012. The first campaign includes measurements between 100 and 173 m and the second 98 and 138 m. In general, the aims were to validate if the results with reference functions and to compare the results from both approaches. The local similarity theory was used, because well above the ground, the assumption of a constant flux layer typically does not hold especially in the stable boundary layer. The used approaches are the flux-gradient and Richardson number formulation. Based on those, the non-dimensional universal functions for momentum and heat could be calculated and those could be presented as functions of the stability parameter. As shown in this study, the scatter the Richardson number formulation results are significant smaller compared to the flux-gradient formulation. One reason can be that the stability parameter and the universal functions for momentum and heat depend solely on the Richardson number. Despite the higher scatter, the medians of the universal function for momentum based on the flux-gradient formulations for both data-sets agree also with the references. Furthermore, for the results of the universal function for heat based on the flux-gradient formulation agree with the references if the minimum limit for the kinetic heat flux is significantly higher than for the universal function for momentum. Furthermore, in the publication from England &amp; McNider 1995, who derived the Richardson number formulation, includes two erroneous equations for stable stratification. One of them has a tipping error and the other was incorrectly derived. Thus, the corrected equations are presented in this work. This work also presents new equations which are not based on the assumption that the constants of the empirical formulation for the universal function for momentum and heat with the same value. A comparison of the old and new equations show for a generated Richardson number vales a agreement of the results over the defined Richardson number range. Finally, in the wind industry it is a common practice to use the mean wind speed at the hub height as the representative mean wind speed over the entire rotor swept area. However, this assumption differs increasingly from the reality, because turbine sizes increase constantly. Thus, in this study, this common method is compared with another averaging concept. Hence, the work focuses on a area-weighted mean wind speed which is called the rotor equivalent wind speed. This average gives a better estimation of the existing wind field because it is based on multiple measurements at various heights. Since the wind gradient changes with height, those two velocities are plotted as functions of the same stability parameter as above. The main results in unstable stratification are that the hub height wind speed underestimates the rotor equivalent wind speed by about 1 to 1.5 %. In stable stratification the results vary: Two calculations show a overestimates by about 1 % and another shows no difference between those averages. Hence, the conclusion based on those findings are that the hub height wind speed is a source for a higher modelling uncertainty. On the contrary, the rotor equivalent wind speed gives more accurate modelling results. / I denna studie beräknades de lokala likhetsteorifunktionerna med två olika tillvägagångssätt och å andra sidan jämförs genomsnittliga vindhastigheten vid navhöjden med rotorekvivalent vindhastigheten. Beräkningarna är baserad på två oberoende datamängder från mätningskampanjer Hornamossen och Ryningsnäs som genomfördes i södra Sverige mellan maj 2015 och juni 2017 och november 2010 och februari 2012. Första kampanj innehåller mätningar mellan 100 och 173 m och den andra 98 och 138 m. Generellt var målet att validera resultaten med referensfunktioner och jämföra både tillvägagångssätt med varandra. Lokala likhetsteorinen används eftersom för mätningar långt över marken håller antagandet om ett konstant flödesskikt vanligtvis inte. Det gäller särskilt i det stabila gränsskiktet. De två tillvägagångssätten är flödesgradientförhållandet och Richardson-talformuleringen. Baserade på de formuleringarna kan de icke-dimensionella universella funktionerna för momentum och värme beräknas och de visas som en funktion av stabilitetsparametern. I denna studie visas att spridningen av Richardsons talformuleringsresultat är signifikant mindre jämfört med andra metoden. En anledning är att stabilitetsparameter och både universella funktioner beror endast på Richardson tal. Trots den högre spridningen överensstämmer medianerna för den universella funktionen för momentum baserat på flödesgradientformuleringarna med referenserna. Detsamma gäller för resultaten av den universella funktionen för värme baserat på flödesgradientformuleringen om minimigränsen om kinetiska värmeflödet är betydligt högre än för den universella funktionen för momentum. Dessutom innehåller publikationen från England &amp; McNider 1995, som innehåller härledning av Richardson talformulering, två felaktiga ekvationer för stabila gränsskiktet. En av dem har ett tippfel och den andra var felaktigt härledd. Detta arbete presenteras de korrigerade ekvationerna. Dessutom presenteras en uppsättning nya ekvationer där de konstanterna av den empiriska formuleringen för den universella funktionen för momentum och värme inte antas att har samma värde. Slutligen är det i vindindustrin en vanlig praxis att använda den genomsnittliga vindhastigheten vid navhöjden som den representativa medelvindhastigheten för hela "rotor swept area". Turbinstorlekarna ökar dock ständigt och därför får skillnaden mellan realitet och beräkningen alltid större. Således fokusera denna studien en areaviktad medelvindhastighet som heter rotorekvivalent vindhastighet. Den beräknar medelvindhastigheten med ett mindre osäkerhet eftersom den är baserad på flera vindmätningar på olika höjder. På grund av ett ojämt vindgradient i gränsskiktet visas resulten som funktion av densamma stailitetsparameter från likhetsteorien. Huvudresultaten för instabil gränskiktet är att navhöjdens vindhastigheten underskattar rotorekvivalent vindhastigheten med cirka 1 till 1,5 %. För det stabila gränskiktet finns olika resultaten: Två beräkningar visar att navhöjdens vindhastigheten överskattningar rotorekvivalent vindhastigheten med ungefär 1 % och en beräkning visa inget skillnad mellan medelvärdarna. Slutsatsen är att navhöjdens vindhastigheten är ett källa till ett högre modelleringsosäkerhet. Däremot visades att användningen av rotorekvivalent vindhastigheten leda till ett bättre prognosresultat. / In dieser Studie wurde einerseits die lokale ähnlichkeitstheorie mit zwei unterschiedlichen Ansätzen berechnet und andererseits die durchschnittliche Nabenhöhen- mit der rotor-äquivalenten Windgeschwin- digkeit verglichen. Dafür standen zwei unabhängige Datensätze zur Verfügung, welche Messwerte zwischen 98 und 173 m beinhalteten. Die Messungen wurden in Südschweden durch die Messtürme Hornamossen und Ryningsnäs in den Zeiträumen von Mai 2015 bis Juni 2017 und von November 2012 bis Februar 2012 erhoben. Das Ziel dieser Studie war es, die Ergebnisse aus den Berechnungen mit Referenzfunktionen zu validieren und den ausgewählten Ansätzen zu vergleichen. Für Messungen mit mehr als 100 m über der Erdoberfläche ist die lokale ähnlichkeitstheorie anstelle der ähnlichkeitstheorie basierend auf der konstanten Flussschicht besser geeignet, da letztere von einem konstanten Wert ausgeht. Die Ansätze, die hierfür verwendet wurden, sind die „Flux-Gradient Formulation“ und die „Gradient Richardson Number Formulation“. Mit beiden kann die universelle Impuls- und Wärmefunktion berechnet und als Funktion des Stabilitätsparameters dargestellt werden. Wie diese Studie zeigt, ist die Streuung um die Referenzkurven sehr klein für die „Gradient Richardson Number“ Ergebnisse im Vergleich zur „Flux-Gradient Formulation“. Dies liegt daran, dass sowohl der Stabilitätsparameter und die universellen Impuls- und Wärmefunktion nur von der Richardson-Zahl abhängen. Trotz der höheren Streuung für die „Flux-Gradient Formulation“ stimmen die Mediane der universellen Impulsfunktionen von beiden Datensätzen und die Referenzkurven überein. Das Gleiche gilt für die Ergebnisse der universellen Wärmefunktion basierend auf der „Flux-Gradient Formulation“, wenn der Mindestwert für den kinetischen Wärmefluss signifikant größer ist als für die universelle Impulsfunktion. Ausgangspunkt ist die Veröffentlichung von England &amp; McNider 1995, welche die „Gradient Richardson Number Formulation“ dargestellt haben. Diese enthält zwei fehlerhafte Gleichungen, wovon eine einen Tippfehler aufweist und die andere auf einer fehlerhaften Herleitung basiert. Diese Arbeit stellt daher ebenso die korrigierten Gleichungen dar. Zusätzlich werden neue Gleichungen vorgestellt, bei denen nicht angenommen wird, dass die von England &amp; McNider angenommenen Konstanten der empirischen Funktionen für die universelle Impuls- und Wärmefunktion den gleichen Wert haben. In der Windindustrie ist es üblich, dass die durchschnittliche Nabenhöhen-Windgeschwindigkeit als Durchschnittsgeschwindigkeit für die gesamte „rotor swept area“ angenommen wird. Diese Annahme weicht immer mehr von der Realität ab, weil Windkraftwerke kontinuierlich größer werden. Daher wird in dieser Arbeit auf eine flächengewichtete mittlere Windgeschwindigkeit mit der Bezeichnung Rotor-äquivalente Windgeschwindigkeit gearbeitet. Diese produziert realistischere Durchschnittswerte, weil sie Messungen von mehreren vertikal verteilten Messpunkten einbezieht. Aufgrund des sich verändernden Windgradientens in der Grenzschicht wird die Abweichung zwischen diesen beiden Geschwindig- keiten als Funktion der Schichtungsstabilität dargestellt. Die zentralen Ergebnisse dieser Studie zeigen zusammenfassend, dass bei labiler Schichtung die Nabenhöhen-Windgeschwindigkeit die Rotor-äquivalente Windgeschwindigkeit um etwa 1 % bis 1.5 % unterschätzt. Für die stabile Schichtung unterscheiden sich die Ergebnisse: Zwei Berechnungen zeigen, dass die Nabenhöhen-Windgeschwindigkeit die Rotor-äquivalente Windgeschwindigkeit um ca. 1 % überschätzt und eine andere Berechnung zeigt keinen Unterschied zwischen den Mittelwerten. Daraus kann gefolgert werden, dass die Nabenhöhen-Windgeschwindigkeit eine höhere Fehlerquelle aufweist. Im Gegensatz dazu liefert die rotor-äquivalente Windgeschwindigkeit genauere Prognosewerte.
938

Inductive elements in pulpit communication of pentecostal churches / Dissertation

Booysen, Willem Matheus 11 1900 (has links)
Discontent with preaching as mode of communication is the problem statement of this study. The authoritative nature of deductive preaching is mirrored by the exploratory, "discovery nature" of inductive models, emphasizing how dialogical preaching is enhanced by incorporating inductive elements into preaching. Meaning production and levels of meaning were studied, and a hermeneutical model for Pentecostal churches were proposed. Dialogical preaching as attitude and principle as well as method was looked at, and the role of interactive participative communication in the dialogic process was described. Special emphasis was placed on the Parable, the metaphor and narrative preaching as models for inductive preaching, and the development and phases of the "plot" was examined. Bridging models between inductive and deductive styles were explored, while two dialogical tools for preparation of sermons were designed. / Practical Theology / Th.M. (Practical theology)
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政府機構轉換資訊科技基礎設施的歷程 / Adopting and Implementing IT infrastructure: A Case Study of the Transformation Process in a Government Agency

汪其芬, Wang, Chi-Fen Unknown Date (has links)
轉換資訊科技基礎設施一如佈建好的房舍遷移重蓋,其涉及的轉換是全面且浩大的工程。在面臨公元二千年危機僅餘兩年的時間,在當時微軟作業平台尚不成熟,國內資訊科技基礎設施轉換成功案例尚不多見,組織內部人員對有關技術一知半解,資訊部門未能有效處理問題等情境下,高階主管採行轉換資訊科技基礎設施策略,將主機移除轉換至區域網路伺服器環境,並重新開發所有應用資訊系統。如此大工程高風險的策略及如此困頓的情境,如何順利進行? 轉換資訊科技基礎設施涉及組織層面極廣而複雜。包括硬體、軟體、程序、制度、人員等。有關機器設備或可一次更新,惟設置於新機器設備上的核心應用資訊系統,則需逐步開發及調整。有關設備、系統及制度標準,如何與組織需求及業務融合發揮效能,更需人員觀念的轉變與不斷的學習,其所需之時間都不是一朝一夕能見其成效。所以轉換資訊科技基礎設施要看的是它的歷程,由時間的演變可以看出轉換資訊科技基礎設施對組織的影響,也可以看出其互動的關聯性。 本研究採用個案研究法,觀察經濟部國際貿易局這個成功案例如何進行資訊科技基礎設施的轉換。該個案有幾個特徵:一、政府機構;二、面臨內外危機及電子化政府的壓力;三、採行的技術策略,對組織而言是一種全面性、突破性(Radical change)的改變,技術無法累積,必需重新學習。 鑑於轉換資訊科技基礎設施歷程十分冗長而複雜,為能有系統的描繪個案,本文採取一般性研究架構(內容、情境及歷程),並輔以「問題解決」觀點描繪轉換資訊科技基礎設施的歷程。又為能適當控制研究資訊量,本文分三大問題(如何形成策略並開始執行?如何整合資訊並推廣應用?資訊部門與人員如何轉型?),加以描述及分析。 有關歷程的特徵,則引用江志浩(1999)所推導出的組織歷程模式—計畫性模式、適應模式、浮現模式加以檢視。該模式係以「問題解決」的二個元素「設定解決問題的目標」、「進度控制與資源配置」,檢視三種歷程模式的特徵及差異。此外,本文並對問題解決者(高階主管、資訊經理、執行團隊)在此歷程中所扮演之角色及其影響加以探索。 本研究發現,轉換資訊科技基礎設施的歷程無法以單一的歷程模式加以描繪。轉換資訊科技基礎設施的歷程涉及一組相關問題的解決,通常在大眾印象中多只看到硬體設施的建置及導入,極易忽略真正困難的問題在於人員觀念的轉變與不斷的學習。由於這些隱藏的問題,整個歷程會出現一些意想不到的狀況。本研究可作為實務界導入資訊科技基礎設施、組織變革及組織創新的參考;對於涉及長達七年轉換歷程的資料,還可以提供未來學術界研究之基礎。 / Adopting and implementing Information Technology (IT) infrastructure , like the removing already-built premises for reconstruction, involves a comprehensive and massive conversion. Less than two years before the Y2K crisis, when the Microsoft platform had not been fully developed, there were only a few successful cases of domestic IT infrastructure adoption and implementation. Moreover, Internal personnel of organization was not proficient with the related technology, and IT department was not able to effectively handle the issues; however , top management adopted a strategy of IT infrastructure conversion by switching the mainframe to Local Area Network servers and then re-developing all the application information systems. How did they successfully implement this strategy amidst such a massive re-engineering, and with high-risk information technology ? In reality, IT infrastructure adoption and implementation involves extremely broad and complicated levels, including hardware, software, procedures, systems, personnel, and so on. Machines and equipment can be updated at once, but the core application information systems installed on new machines and equipment must be sequentially developed and adjusted. To achieve the desired effects, people especially, need to change their ways of thinking and learn constantly if they want their equipment, systems, and system standards to be aligned with the needs and business goals of the organization. However, results cannot be achieved in a short time. Therefore the IT infrastructure adoption and implementation process needs to be studied longitudinally. With respect to time, we can see the impact of IT infrastructure adaptation on organizational changes and its interactive association. This study uses the case study approach to observe how the Bureau of Foreign Trade of the Ministry of Economic Affairs in Taiwan has successfully adopted and implemented IT infrastructure. This case is characterized by the following properties: (1) It is a government organization; (2) It encountered internal and external challenges and pressure to launch an “e-Government;” and (3) It used technological strategies, which are comprehensive and radical changes to organization, so that the technologies involved were unable to be accumulated and needed be relearned. As it is a very long and complicated process to adopt and implement IT infrastructure, this article uses a general research framework (consisting of contents, context, and processes), supplemented by “problem solving”, to systematically describe the IT infrastructure adoption and implementation process. Moreover, with the hope of properly controlling the information for this research, three major issues are described and analyzed: (1) How to formulate and implement strategies; (2) How to integrate and apply information; and (3) How to transform the information system department and its personnel. Additionally, the characteristics of a transformation process can be studied using the organizational process model derived by Chiang Chi-ku (1999), comprising of a planned model, an adaptive model, and an emergent model. This organizational process model studies the properties and differences of these three process models using the two components of “problem solving” —“goal setting for problem solving” and “status control and resource allocation.” Moreover, this article also studies the roles played by the problem solvers (i.e., top management, information manager, and the executive team) in these processes and their effects. According to the findings of this study, the process of adopting and implementing IT infrastructure can’t be described as a single process. Moreover, it involves solutions to a series of related problems. Generally speaking, most people only recognize the construction and implementation of hardware, but easily disregard the real difficulty in personnel’s conceptual change and constant learning. Due to these hidden problems, some unexpected conditions may appear throughout the transformation process. Hence, this research can be taken as a reference for the business sector in adopting and implementing of IT infrastructure, organizational change, and organizational innovation. Moreover, it can also provide the basis for future academic research of the data involving a seven-year-long adaptation process.
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Solution Methods for Service Network Design with Resource Management Consideration

Vu, Duc Minh 06 1900 (has links)
La gestion des ressources, équipements, équipes de travail, et autres, devrait être prise en compte lors de la conception de tout plan réalisable pour le problème de conception de réseaux de services. Cependant, les travaux de recherche portant sur la gestion des ressources et la conception de réseaux de services restent limités. La présente thèse a pour objectif de combler cette lacune en faisant l’examen de problèmes de conception de réseaux de services prenant en compte la gestion des ressources. Pour ce faire, cette thèse se décline en trois études portant sur la conception de réseaux. La première étude considère le problème de capacitated multi-commodity fixed cost network design with design-balance constraints(DBCMND). La structure multi-produits avec capacité sur les arcs du DBCMND, de même que ses contraintes design-balance, font qu’il apparaît comme sous-problème dans de nombreux problèmes reliés à la conception de réseaux de services, d’où l’intérêt d’étudier le DBCMND dans le contexte de cette thèse. Nous proposons une nouvelle approche pour résoudre ce problème combinant la recherche tabou, la recomposition de chemin, et une procédure d’intensification de la recherche dans une région particulière de l’espace de solutions. Dans un premier temps la recherche tabou identifie de bonnes solutions réalisables. Ensuite la recomposition de chemin est utilisée pour augmenter le nombre de solutions réalisables. Les solutions trouvées par ces deux méta-heuristiques permettent d’identifier un sous-ensemble d’arcs qui ont de bonnes chances d’avoir un statut ouvert ou fermé dans une solution optimale. Le statut de ces arcs est alors fixé selon la valeur qui prédomine dans les solutions trouvées préalablement. Enfin, nous utilisons la puissance d’un solveur de programmation mixte en nombres entiers pour intensifier la recherche sur le problème restreint par le statut fixé ouvert/fermé de certains arcs. Les tests montrent que cette approche est capable de trouver de bonnes solutions aux problèmes de grandes tailles dans des temps raisonnables. Cette recherche est publiée dans la revue scientifique Journal of heuristics. La deuxième étude introduit la gestion des ressources au niveau de la conception de réseaux de services en prenant en compte explicitement le nombre fini de véhicules utilisés à chaque terminal pour le transport de produits. Une approche de solution faisant appel au slope-scaling, la génération de colonnes et des heuristiques basées sur une formulation en cycles est ainsi proposée. La génération de colonnes résout une relaxation linéaire du problème de conception de réseaux, générant des colonnes qui sont ensuite utilisées par le slope-scaling. Le slope-scaling résout une approximation linéaire du problème de conception de réseaux, d’où l’utilisation d’une heuristique pour convertir les solutions obtenues par le slope-scaling en solutions réalisables pour le problème original. L’algorithme se termine avec une procédure de perturbation qui améliore les solutions réalisables. Les tests montrent que l’algorithme proposé est capable de trouver de bonnes solutions au problème de conception de réseaux de services avec un nombre fixe des ressources à chaque terminal. Les résultats de cette recherche seront publiés dans la revue scientifique Transportation Science. La troisième étude élargie nos considérations sur la gestion des ressources en prenant en compte l’achat ou la location de nouvelles ressources de même que le repositionnement de ressources existantes. Nous faisons les hypothèses suivantes: une unité de ressource est nécessaire pour faire fonctionner un service, chaque ressource doit retourner à son terminal d’origine, il existe un nombre fixe de ressources à chaque terminal, et la longueur du circuit des ressources est limitée. Nous considérons les alternatives suivantes dans la gestion des ressources: 1) repositionnement de ressources entre les terminaux pour tenir compte des changements de la demande, 2) achat et/ou location de nouvelles ressources et leur distribution à différents terminaux, 3) externalisation de certains services. Nous présentons une formulation intégrée combinant les décisions reliées à la gestion des ressources avec les décisions reliées à la conception des réseaux de services. Nous présentons également une méthode de résolution matheuristique combinant le slope-scaling et la génération de colonnes. Nous discutons des performances de cette méthode de résolution, et nous faisons une analyse de l’impact de différentes décisions de gestion des ressources dans le contexte de la conception de réseaux de services. Cette étude sera présentée au XII International Symposium On Locational Decision, en conjonction avec XXI Meeting of EURO Working Group on Locational Analysis, Naples/Capri (Italy), 2014. En résumé, trois études différentes sont considérées dans la présente thèse. La première porte sur une nouvelle méthode de solution pour le "capacitated multi-commodity fixed cost network design with design-balance constraints". Nous y proposons une matheuristique comprenant la recherche tabou, la recomposition de chemin, et l’optimisation exacte. Dans la deuxième étude, nous présentons un nouveau modèle de conception de réseaux de services prenant en compte un nombre fini de ressources à chaque terminal. Nous y proposons une matheuristique avancée basée sur la formulation en cycles comprenant le slope-scaling, la génération de colonnes, des heuristiques et l’optimisation exacte. Enfin, nous étudions l’allocation des ressources dans la conception de réseaux de services en introduisant des formulations qui modèlent le repositionnement, l’acquisition et la location de ressources, et l’externalisation de certains services. À cet égard, un cadre de solution slope-scaling développé à partir d’une formulation en cycles est proposé. Ce dernier comporte la génération de colonnes et une heuristique. Les méthodes proposées dans ces trois études ont montré leur capacité à trouver de bonnes solutions. / Resource management in freight transportation service network design is an important issue that has been studied extensively in recent years. Resources such as vehicles, crews, etc. are factors that can not be ignored when designing a feasible plan for any service network design problem. However, contributions related to resource management issues and service network design are still limited. The goal of the thesis is to fill this gap by taking into account service network design problems with resource management issues. In this thesis, we propose and address three service network design problems that consider resource management. In the first study, we consider the capacitated multi-commodity fixed cost network design with design-balance constraints which is a basic sub-problem for many service design problems because of the capacitated multi-commodity structure as well as its design-balance property. We propose a three-phase matheuristic that combines tabu-search, path-relinking and an exactbased intensification procedure to find high quality solutions. Tabu-search identifies feasible solutions while path-relinking extends the set of feasible solutions. The solutions found by these two meta-heuristics are used to fix arcs as open or close. An exact solver intensifies the search on a restricted problem derived from fixing arcs. The experiments on benchmark instances show that the solution approach finds good solutions to large-scale problems in a reasonable amount of time. The contribution with regard to this study has been accepted in the Journal of Heuristics. In the second study, together with the consideration of the design of routes to transport a set of commodities by vehicles, we extend resources management by explicitly taking account of the number of available vehicles at each terminal. We introduce a matheuristic solution framework based on a cycle-based formulation that includes column generation, slope-scaling, heuristic and exact optimization techniques. As far as we know, this is the first matheuristic procedure developed for a cycle-based formulation. The column generation solves the linear relaxation model and provides a set of cycles to define the approximation model used in slopescaling loop. A heuristic is used to convert each solution to the approximation problem into a feasible solution. Memory-based perturbation procedure is used to enhance the performance of the algorithm. Experiments show that the proposed algorithm is able to find good feasible solutions for the problem. The contribution with regard to this study has been accepted for publication in Transportation Science. In the third study, we examine resources allocation issues in service network design. We aim to address a number of fleet utilization issues which usually appear at the beginning of the season because of the change of demand patterns: 1) reposition resources among terminals to account for shifts in demand patterns; 2) acquire (buy or long-term rent) new resources and as sign them to terminals; 3) outsource particular services. We present an integrated formulation combining these selection-location and scheduled service design decisions. The mixed-integer formulation is defined over a time-space network, the initial period modeling the location de cisions on resource acquisition and positioning, while the decisions on service selection and scheduling, resource assignment and cycling routing, and demand satisfaction being modeled on the rest of the network. We also present a matheuristic solution method combining slope scaling and column generation, discuss its algorithmic performance, and explore the impact of combining the location and design decisions in the context of consolidation carrier service design. This study will be presented at XII International Symposium On Locational Deci sion, in conjunction with the XXI Meeting of EURO Working Group on Locational Analysis, Naples/Capri (Italy), 2014. In summary, three studies are considered in this thesis. The first one considers the capaciated multi-commodity fixed cost network design with design-balance constraints, a basic problem in many service network design problems with design-balance constraints. We propose an ef ficient three-phase matheuristic solution method that includes tabu search, path relinking and exact optimization. In the second study, we propose a new service network design model that takes into account resources limitations at each terminal. We also propose an advanced matheuristic framework solution method based on a cycle-based formulation which includes slope-scaling, column generation, heuristics and exact optimization for this problem. The last study addresses resources allocation issues in service network design. We introduce formula tions that model the reposition, acquisition/renting of resources and outsourcing of services. A solution framework based on the slope-scaling approach on cycle-based formulations is pro posed. Tests indicate that these proposed algorithms are able to find good feasible solutions for each of threse problems.

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