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Phillips, John Michael. "Variable Strategy Model of the Human Operator." Diss., Virginia Tech, 2000. http://hdl.handle.net/10919/28496.
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Human operators often employ discontinuous or "bang-bang" control strategies when performing large-amplitude acquisition tasks. The current study applies Variable Structure Control (VSC) techniques to model human operator behavior during acquisition tasks. The result is a coupled, multi-input model replicating the discontinuous control strategy. In the VSC formulation, a switching surface is the mathematical representation of the operator's control strategy. The performance of the Variable Strategy Model (VSM) is evaluated by considering several examples, including the longitudinal control of an aircraft during the visual landing task. The aircraft landing task becomes an acquisition maneuver whenever large initial offsets occur. Several different strategies are explored in the VSM formulation for the aircraft landing task. First, a switching surface is constructed from literal interpretations of pilot training literature. This approach yields a mathematical representation of how a pilot is trained to fly a generic aircraft. This switching surface is shown to bound the trajectory response of a group of pilots performing an offset landing task in an aircraft simulator study. Next, front-side and back-side landing strategies are compared. A back-side landing strategy is found to be capable of landing an aircraft flying on either the front side or back side of the power curve. However, the front-side landing strategy is found to be insufficient for landing an aircraft flying on the back side. Finally, a more refined landing strategy is developed that takes into the account the specific aircraft's dynamic characteristics. The refined strategy is translated back into terminology similar to the existing pilot training literature.Ph. D.
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Patterson, Cameron Webster. "An Economic Model of Subscriber Offloading Between Mobile Network Operators and a WLAN Operator." Thesis, Virginia Tech, 2014. http://hdl.handle.net/10919/50660.
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With increasing mobile data demand there is a push towards heterogeneous networks. Small-scale operators (SSOs) of WLANs are becoming more prevalent, while Mobile Network Operators (MNOs) seek an outlet for their customers' data usage. These conditions prompt the need for an effective relationship between the two parties for the purpose of offloading cellular data traffic to WLANs in a way that is economically beneficial to all involved. This thesis presents a model of such a relationship, in which the SSO sets a strategic offloading price per subscriber and several MNOs can choose how many subscribers they want to offload in order to minimize their costs. We determine the optimal offloading price, identify how the SSO incorporates its own network's quality of service (QoS) into its price decision, and examine the way in which the MNOs' cost structures affect their ability to offload. This model can be applied by both MNOs and SSOs to make informed network deployment decisions, even before engaging in an offloading relationship.Master of Science
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Magne, Sofie, and Jacob Stenswed. "Revenue Management Applicability on Coworking Space : Operator Perspective." Thesis, KTH, Fastigheter och byggande, 2019. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-254813.
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This thesis explores the potential use and implementation of a revenuemanagement model for coworking operators. With a critical realism philosophyand abductive approach, a quantitative study using primary data from a coworkingoperator has been conducted. Based on a comprehensive literature review, wehave found that much research is done on revenue management in the airline andhotel industries. However, we found no research on revenue management modelsthat intend to optimize revenue for coworking operations. Hence, this thesis aimsto fill this gap in existing academic research. Features from revenue managementmodels used in the hotel and airline industries are identified and analyzed with theobjective of implementing these in the coworking industry to efficiently maximizerevenue. The paper proposes the use of multinomial logit (MNL) model in theprocess of market segmentation; this method allows one to determine whichfactors influence the different segments. Moreover, the MNL model is used todefine the demand function from which a probability (probable?) distributionof total demand can be separated into demands representing each product class.Furthermore, the demand is used to calculate protection limits according to theExpected Marginal Seat Revenue (EMSR) model, with the objective of allocatingcapacity to the highest-yielding customers.Results indicate that the MNL regression is an effective tool to analyze themarket segmentation and demand allocation for coworking operators. Afterour successful analysis, we are prepared to argue with confidence that revenuemanagement models are applicable to coworking operations.I denna uppsats undersöker vi den potentiella användningen och genomförandetav intäktsoptimeringsmodeller för coworking operatörer. En kvantitativ studiemed primär data från en coworking operatör har genomförts med en kritiskrealismfilosofi och ett abduktivt tillvägagångssätt. Det finns mycket forskningkring intäktsoptimering, framför allt inom flyg- och hotellbranschen, men ingensom behandlar intäktsoptimeringsmodeller med avseendepå coworking operatörer. Denna masteruppsats syftar till att bidra med kunskapför att fylla gapet kring revenue management för coworkingkontor, som saknas ibefintlig, svensk akademisk forskning idag.Vitala funktioner som utgör intäktoptimeringsmodeller ämnade för hotellochflygindustrin har identifierats och analyserats med målet att utforskamöjlig implementering för coworkingoperatörer. I uppsatsen genomförsen marknadssegmentering med hjälp av en multinomial regressionsanalys.Vidare görs en multinomial regressionsanalys med samtliga produktklasser somberoende variabler, för att få ut sannolikhetsfördelningen för vilka produkter somefterfrågas av den totala efterfrågan. Resultatet kan användas för att optimeratotala intäkterna genom att beräkna hur många platser som bör reserveras åthögt avkastande kunder, och hur många som kan hyras ut i tidigt skede. Förändamålet har vi tillämpat den så kallade Expected Marginal Seat Revenuemetoden, EMSR.Resultatet indikerar att multinomial logistisk regression är ett effektivt sätt attanalysera marknadssegment och styra efterfrågan till önskad produktklass. Samtatt användandet av rekommenderad revenue management modell är applicerbarpå coworking verksamheter. Alternativt: Resultatet indikerar att: i. multinomiallogistisk regression är ett effektivt sätt att analysera marknadssegment och styraefterfrågan till önskad produktklass. ii. användandet av rekommenderad revenuemanagement modell är applicerbar på coworking verksamheter.
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Guo, Yisong. "Using Agent-Based Models to Understand Multi-Operator Supervisory Control." BYU ScholarsArchive, 2012. https://scholarsarchive.byu.edu/etd/2970.
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As technology advances, many practical applications require human-controlled robots. For such applications, it is useful to determine the optimal number of robots an operator should control to maximize human efficiency given different situations. One way to achieve this is through computer simulations of team performance. In order to factor in various parameters that may affect team performance, an agent-based model will be used. Agent-based modeling is a computational method that enables a researcher to create, analyze, and experiment with models composed of agents that interact within an environment [12]. We construct an agent-based model of humans interacting with robots, and explore how team performance relates to different agent parameters and team organizational structures [21]. Prior work describes interaction between a single operator and multiple robots, while this work includes multi-operator performance and coordination. Model parameters include neglect time, interaction time, operator slack time, level of robot autonomy, etc. Understanding the parameters that influence team performance will be a step towards finding ways to maximize performance in real life human-robot systems.
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Wytock, Matt. "Optimizing Optimization: Scalable Convex Programming with Proximal Operators." Research Showcase @ CMU, 2016. http://repository.cmu.edu/dissertations/785.
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Convex optimization has developed a wide variety of useful tools critical to many applications in machine learning. However, unlike linear and quadratic programming, general convex solvers have not yet reached sufficient maturity to fully decouple the convex programming model from the numerical algorithms required for implementation. Especially as datasets grow in size, there is a significant gap in speed and scalability between general solvers and specialized algorithms. This thesis addresses this gap with a new model for convex programming based on an intermediate representation of convex problems as a sum of functions with efficient proximal operators. This representation serves two purposes: 1) many problems can be expressed in terms of functions with simple proximal operators, and 2) the proximal operator form serves as a general interface to any specialized algorithm that can incorporate additional `2-regularization. On a single CPU core, numerical results demonstrate that the prox-affine form results in significantly faster algorithms than existing general solvers based on conic forms. In addition, splitting problems into separable sums is attractive from the perspective of distributing solver work amongst multiple cores and machines. We apply large-scale convex programming to several problems arising from building the next-generation, information-enabled electrical grid. In these problems (as is common in many domains) large, high-dimensional datasets present opportunities for novel data-driven solutions. We present approaches based on convex models for several problems: probabilistic forecasting of electricity generation and demand, preventing failures in microgrids and source separation for whole-home energy disaggregation.
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Filla, Reno. "Operator and Machine Models for Dynamic Simulation of Construction Machinery." Licentiate thesis, Linköping : Linköpings universitet, 2005. http://urn.kb.se/resolve?urn=urn:nbn:se:liu:diva-4092.
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Huang, Dongliang. "Studies on Identification of Continuous-Time Systems Based on δ-Operator Model." 京都大学 (Kyoto University), 2001. http://hdl.handle.net/2433/150617.
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Hickel, Tilmann. "Theory of many body effects in the Kondo lattice model projection operator method /." [S.l.] : [s.n.], 2005. http://deposit.ddb.de/cgi-bin/dokserv?idn=980739764.
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Cao, Zhenwei. "Quantum evolution: The case of weak localization for a 3D alloy-type Anderson model and application to Hamiltonian based quantum computation." Diss., Virginia Tech, 2012. http://hdl.handle.net/10919/19205.
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Over the years, people have found Quantum Mechanics to be extremely useful in explaining various physical phenomena from a microscopic point of view. Anderson localization, named after physicist P. W. Anderson, states that disorder in a crystal can cause non-spreading of wave packets, which is one possible mechanism (at single electron level) to explain metalinsulator transitions. The theory of quantum computation promises to bring greater computational power over classical computers by making use of some special features of Quantum Mechanics. The first part of this dissertation considers a 3D alloy-type model, where the Hamiltonian is the sum of the finite difference Laplacian corresponding to free motion of an electron and a random potential generated by a sign-indefinite single-site potential. The result shows that localization occurs in the weak disorder regime, i.e., when the coupling parameter λ is very small, for energies E ≤ −Cλ² . The second part of this dissertation considers adiabatic quantum computing (AQC) algorithms for the unstructured search problem to the case when the number of marked items is unknown. In an ideal situation, an explicit quantum algorithm together with a counting subroutine are given that achieve the optimal Grover speedup over classical algorithms, i.e., roughly speaking, reduce O(2n ) to O(2n/2 ), where n is the size of the problem. However, if one considers more realistic settings, the result shows this quantum speedup is achievable only under a very rigid control precision requirement (e.g., exponentially small control error).Ph. D.
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Li, Xiawen. "Power System Stability Improvement with Decommissioned Synchronous Machine Using Koopman Operator Based Model Predictive Control." Diss., Virginia Tech, 2019. http://hdl.handle.net/10919/102503.
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Traditional generators have been decommissioned or replaced by renewable energy generation due to utility long-standing goals. However, instead of flattening the entire plant, the rotating mass of generator can be utilized as a storage unit (inertia resource) to mitigate the frequency swings during transient caused by the renewables. The goal of this work is to design a control strategy utilizing the decommissioned generator interfaced with power grid via a back-to-back converter to provide inertia support. This is referred to as decoupled synchronous machine system (DSMS). On top of that, the grid-side converter is capable of providing reactive power as an auxiliary voltage controller. However, in a practical setting, for power utilities, the detailed state equations of such device as well as the complicated nonlinear power system are usually unobtainable making the controller design a challenging problem. Therefore, a model free, purely data-driven strategy for the nonlinear controller design using Koopman operator-based framework is proposed. Besides, the time delay embedding technique is adopted together with Koopman operator theory for the nonlinear system identification. Koopman operator provides a linear representation of the system and thereby the classical linear control algorithms can be applied. In this work, model predictive control is adopted to cope with the constraints of the control signals. The effectiveness and robustness of the proposed system are demonstrated in Kundur two-area system and IEEE 39-bus system.Doctor of Philosophy
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Zeng, Yuefei [Verfasser]. "Efficient Radar Forward Operator for Operational Data Assimilation within the COSMO-model / Yuefei Zeng." Karlsruhe : KIT Scientific Publishing, 2014. http://www.ksp.kit.edu.
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Al-Balushi, Rashid Ali Ibrahim. "An Enterprise Project Management Model (EPMM) for the transformation of a telecommunication operator organization." Thesis, Heriot-Watt University, 2006. http://hdl.handle.net/10399/166.
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Sinani, Klajdi. "Finite Horizon Optimality and Operator Splitting in Model Reduction of Large-Scale Dynamical System." Diss., Virginia Tech, 2020. http://hdl.handle.net/10919/99358.
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Simulation, design, and control of dynamical systems play an important role in numerous scientific and industrial tasks. The need for detailed models leads to large-scale dynamical systems, posing tremendous computational difficulties when employed in numerical simulations. In order to overcome these challenges, we perform model reduction, replacing the large-scale dynamics with high-fidelity reduced representations. There exist a plethora of methods for reduced order modeling of linear systems, including the Iterative Rational Krylov Algorithm (IRKA), Balanced Truncation (BT), and Hankel Norm Approximation. However, these methods generally target stable systems and the approximation is performed over an infinite time horizon. If we are interested in a finite horizon reduced model, we utilize techniques such as Time-limited Balanced Truncation (TLBT) and Proper Orthogonal Decomposition (POD). In this dissertation we establish interpolation-based optimality conditions over a finite horizon and develop an algorithm, Finite Horizon IRKA (FHIRKA), that produces a locally optimal reduced model on a specified time-interval. Nonetheless, the quantities being interpolated and the interpolant are not the same as in the infinite horizon case. Numerical experiments comparing FHIRKA to other algorithms further support our theoretical results.
Next, we discuss model reduction for nonlinear dynamical systems. For models with unstructured nonlinearities, POD is the method of choice. However, POD is input dependent and not optimal with respect to the output. Thus, we use operator splitting to integrate the best features of system theoretic approaches with trajectory based methods such as POD in order to mitigate the effect of the control inputs for the approximation of nonlinear dynamical systems. We reduce the linear terms with system theoretic methods and the nonlinear terms terms via POD. Evolving the linear and nonlinear terms separately yields the reduced operator splitting solution. We present an error analysis for this method, as well as numerical results that illustrate the effectiveness of our approach. While in this dissertation we only pursue the splitting of linear and nonlinear terms, this approach can be implemented with Quadratic Bilinear IRKA or Balanced Truncation for Quadratic Bilinear systems to further diminish the input dependence of the reduced order modeling.Doctor of Philosophy
Simulation, design, and control of dynamical systems play an important role in numerous scientific and industrial tasks such as signal propagation in the nervous system, heat dissipation, electrical circuits and semiconductor devices, synthesis of interconnects, prediction of major weather events, spread of fires, fluid dynamics, machine learning, and many other applications. The need for detailed models leads to large-scale dynamical systems, posing tremendous computational difficulties when applied in numerical simulations. In order to overcome these challenges, we perform model reduction, replacing the large-scale dynamics with high-fidelity reduced representations. Reduced order modeling helps us to avoid the outstanding burden on computational resources. Numerous model reduction techniques exist for linear models over an infinite horizon. However, in practice we usually are interested in reducing a model over a specific time interval. In this dissertation, given a reduced order, we present a method that finds the best local approximation of a dynamical system over a finite horizon. We present both theoretical and numerical evidence that supports the proposed method. We also develop an algorithm that integrates operator splitting with model reduction to solve nonlinear models more efficiently while preserving a high level of accuracy.
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Paul, Tiffany M. "Application of the Augmented Operator Function Model for Developing Performance Metrics in Persistent Surveillance." Wright State University / OhioLINK, 2013. http://rave.ohiolink.edu/etdc/view?acc_num=wright1389657226.
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Hickel, Tilmann. "Theory of many-body effects in the Kondo-lattice model." Doctoral thesis, Humboldt-Universität zu Berlin, Mathematisch-Naturwissenschaftliche Fakultät I, 2006. http://dx.doi.org/10.18452/15500.
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Das magnetische Verhalten zahlreicher Materialien lässt sich auf eine indirekte Wechselwirkung lokalisierter magnetischer Momente, vermittelt durch die Elektronen eines Leitungsbandes, zurückführen. Das Kondo-Gitter-Modell hat sich als elegante Möglichkeit bewährt, diesen Prozess quantenmechanisch zu beschreiben. Es reduziert die Physik auf eine intraatomare Wechselwirkung der Spins von lokalisierten und itineranten Elektronen. Die vorliegende Arbeit ist den analytischen Eigenschaften dieses Modells gewidmet. Die besondere Herausforderung des Kondo-Gitter-Modells besteht dabei im Zusammenwirken zweier verschiedener Teilchensorten, beschrieben durch Fermi-Operatoren sowie quantenmechanische Spins. Bisherige Untersuchungen haben sich in der Regel nur auf eine der beiden Teilchensorten konzentriert. Mit der Projektions-Operator-Methode stellen wir eine Möglichkeit vor, beide Teilsysteme in gleicher Qualität zu behandeln. Die Auswertung des Teilsystems der itineranten Elektronen führt auf einen Ausdruck für die Selbstenergie, der lineare und quadratische Effekte in der Wechselwirkung exakt beschreibt. Die resultierenden Zustandsdichten weisen starke Korrelationseffekte auf. Deren Untersuchung dient sowohl der Bestätigung von Ergebnissen weniger systematischer Zugänge als auch dem Aufzeigen neuer Vielteilchen-Phänomene. Die Anwendung der Projektions-Operator-Methode auf das System der lokalisierten Momente führt zu einer Analyse der bereits bekannten RPA (random phase approximation). Zu diesem Zweck werden die Magnonenspektren und die Curie-Temperaturen systematisch untersucht. Dabei treten bisher unbekannte Schwachpunkte der RPA zu Tage, die auch die Kombination mit Theorien für das itinerante Teilsystem verhindern. Verbesserungen und Alternativen zur RPA werden diskutiert.The magnetic behaviour of various materials is due to an indirect interaction of localized magnetic moments, which is based on itinerant electrons in a conduction band. The Kondo-lattice model is an elegant approach for a quantum-mechanical description of this process. It reduces the relevant physics to an intra-atomic exchange interaction of the localized and the itinerant electrons. The aim of the present work is a detailed investigation of analytic properties of this model. Here, the interplay of two distinct types of particles, described by Fermi operators and quantum-mechanical spin operators respectively, is a major challenge of the considered model. Previous studies have focused on one of these subsystems only. Using the projection-operator method, we suggest an efficient way to describe both subsystems on the same level of approximation. An evaluation of the subsystem of itinerant electrons yields an expression for the self-energy, which describes linear and quadratic interaction effects exactly. The densities of states derived with this theory show strong correlation effects. We were able to assess results obtained with less systematic approaches and to predict new many-particle effects. The application of the projection-operator method to the subsystem of localized magnetic moments results in a detailed analysis of the RPA (random phase approximation). The dependence of magnon spectra and Curie temperatures on model parameters are investigated systematically. Previously unknown drawbacks of the RPA are revealed, which prevent the combination of these results with theories for the itinerant subsystem. Improvements beyond RPA and alternative approximations are discussed.
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Filla, Reno. "Quantifying Operability of Working Machines." Doctoral thesis, Linköpings universitet, Fluida och mekatroniska system, 2011. http://urn.kb.se/resolve?urn=urn:nbn:se:liu:diva-70394.
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In working machines the human operator is essential for the performance of the total system. Productivity and energy efficiency are both dependent not only on inherent machine properties and working place conditions, but also on how the operator manoeuvres the machine. In order to operate energy-efficient the operator has to experience the machine as harmonic. This is important to consider during the development of such working machines. It is necessary to quantify operability and to include this interaction between the human operator and the machine in both the later stages of a development project (where physical prototypes are evaluated by professional test operators) as well as in the earlier stages like concept design (where only virtual prototypes are available). The influence of the human operator is an aspect that is traditionally neglected in dynamic simulations conducted in concept design, because the modelling needs to be extended beyond the technical system. The research presented in this thesis shows two approaches to rule-based simulation models of a wheel loader operator. Both operator models interact with the machine model just as a human operator does with the actual machine. It is demonstrated that both operator models are able to adapt to basic variations in workplace setup and machine capability. A “human element” can thus be introduced into dynamic simulations of working machines, providing more relevant answers with respect to operator-influenced complete-machine properties such as productivity and energy efficiency. While the influence of the human operator is traditionally ignored when evaluating machine properties in the early stages of the product development process, later stages are very reliant on professional test operators using physical prototypes. The presented research demonstrates how the traditional subjective evaluation of a machine’s operability can be complemented by a calculated measure for the operator’s control effort, derived from the recorded control commands of the machine operator. This control effort measure can also be calculated from the control commands of an operator model in a simulation, such as those presented in this thesis. It thus also allows for an assessment of operability already in the concept design phase. In addition, the results of a study of quantifying operator workload by means of measuring psycho-physiological data such as heart rate variability and respiration rate are presented as the first step towards realising workload-adaptive operator assistance functions. Once fully developed, the method itself can also be used as another complement to the traditional subjective evaluations of operability. This approach can then be applied not only in testing of physical prototypes, but also earlier in the product development process in studies on human-in-the-loop simulators.I arbetsmaskiner spelar föraren en avgörande roll för maskinens prestanda. Såväl produktivitet som energieffektivitet beror inte enbart av maskinens egenskaper och arbetsomgivningen, utan beror också av sättet på vilket föraren manövrerar maskinen. För att främja ett bränslesnålt körsätt ska maskinerna upplevas som harmoniska och det är viktigt att beakta detta vid utvecklingen. Det är nödvändigt att kvantifiera maskinharmonin och att ta hänsyn till interaktionen mellan föraren och maskinen i alla steg av ett utvecklingsprojekt. Detta gäller såväl sena faser, när fysiska prototyper redan har tagits fram och utvärderas av professionella provförare, såväl som tidiga faser som konceptutveckling, när endast virtuella prototyper finns tillgängliga. Förarens inflytande beaktas traditionellt inte i prestandasimuleringar i konceptfasen, eftersom detta innebär att mer än enbart det tekniska systemet måste modelleras. I den forskningen som presenteras här visas två olika regelbaserade modeller av hjullastarförare. Båda förarmodellerna använder maskinmodellen på samma sätt som en verklig förare använder en verklig maskin. Det visas att båda förarmodellerna kan anpassa sig till förändringar både i arbetsomgivningen och i maskinens egenskaper. I och med detta kan man utöka dynamiska simuleringar av arbetsmaskiner med ”ett mänskligt element”. Detta ger bättre resultat vad gäller produktivitet, energieffektivitet och liknande egenskaper som föraren påverkar i kompletta maskiner. Medan man i tidiga faser av produktutvecklingsprocessen traditionellt bortser från förarens inflytande, så är man i senare faser mycket beroende av att professionella provförare testar fysiska prototyper. Den här presenterade forskningen visar hur den traditionella subjektiva förarbedömningen av en maskins körbarhet kan kompletteras med ett mått på förarens ”spakarbete”, som beräknas utifrån en mätning på hur föraren använder sina kontroller för att styra maskinen. Detta mått på ”spakarbete” kan också beräknas utifrån de spaksignaler som genereras av förarmodellerna i en simulering. I och med detta kan en maskins körbarhet undersökas redan under konceptutvecklingen. I avhandlingen redovisas också resultaten från en studie som gjorts i syfte att kvantifiera förarens arbetsbelastning genom att mäta psykofysiologiska mått som variationer i hjärtfrekvens och andningsfrekvens. Studien är ett första steg mot att förverkliga en vision av stödfunktioner i arbetsmaskiner vilka anpassar sig efter förarens momentana arbetsbelastning. En sådan metod att mäta förarens arbetsbelastning kan också användas som ett komplement till den traditionella subjektiva förarbedömningen av en maskins körbarhet. Metoden kan inte bara användas vid provning av fysiska prototyper utan också tidigare i produktutvecklingsprocessen vid studier i avancerade körsimulatorer.
IN ARBETSMASCHINEN spielt der Fahrer eine entscheidende Rolle für die Leistung des gesamten Systems. Produktivität und Energieeffizienz sind nicht nur abhängig von den Grundeigenschaften der Maschine und den Bedingungen am Einsatzort, sondern auch von der Art und Weise wie der Fahrer die Maschine manövreriert. Für eine kraftstoffsparende Fahrweise muss der Fahrer die Maschine als harmonisch erleben. Dies muss bei der Entwicklung beachtet werden. Das Erfassen der Fahrbarkeit und die Berücksichtigung des Zusammenspiels zwischen Fahrer und Maschine ist in allen Phasen der Entwicklung notwendig, sowohl in den späteren Phasen, wenn Prototypen von Erprobungsfahrern ausgewertet werden, als auch in den frühen Phasen wie dem Konzeptentwurf, wenn nur virtuelle Prototypen vorhanden sind. Der Fahrereinfluss wird traditionell in den dynamischen Simulationen während des Konzeptentwurfs vernachlässigt, denn er erfordert die Ausweitung der Modellierung über das technische System hinaus. In dieser Dissertation werden zwei Herangehensweisen zur Erstellung regelbasierter Modelle eines Radladerfahrers aufgezeigt. Beide Fahrermodelle interagieren mit dem Maschinenmodell gleich einem menschlichen Fahrer mit einer realen Maschine. Es wird gezeigt, dass beide Fahrermodelle in der Lage sind, sich auf Änderungen des Einsatzortes und der Maschineneigenschaften anzupassen. Somit kann „ein menschliches Element“ in die dynamische Simulation von Arbeitsmaschinen eingeführt werden, was zu qualitativ besseren Resultaten bezüglich Produktivität, Energieeffizienz und ähnlicher fahrerbeeinflusster Eigenschaften führt. Während man in den frühen Phasen der Produktentwicklung traditionell vom Fahrereinfluss absieht, ist man später sehr auf die Erprobung physischer Prototypmaschinen durch professionelle Testfahrer angewiesen. In dieser Dissertation wird aufgezeigt, wie die traditionell subjektive Bewertung der Fahrbarkeit einer Maschine mit einem Maß der „Steuerungsarbeit“ komplettiert werden kann, berechnet aus der gemessenen Betätigung der dem Fahrer zur Verfügung stehenden Bedienelemente. Dieses Maß der „Steuerungsarbeit“ kann auch aus den Signalen der von uns vorgestellten Fahrermodelle in einer Simulation berechnet werden. Damit kann man die Fahrbarkeit bereits in der Konzeptentwicklung abschätzen. Weiterhin werden die Resultate einer Studie zur Quantifizierung der Fahrerbelastung mithilfe psychophysiologischer Daten wie Veränderungen der Herzfrequenz und Atmungsfrequenz vorgestellt. Diese Studie ist ein erster Schritt zur Entwicklung eines Assistenzsystemes, dass sich an die aktuelle Fahrerbelastung anpasst. Eine solche Messmethode der Fahrerbelastung kan auch zusätzlich zur traditionellen subjektiven Fahrbarkeitseinschätzung angewendet werden – nicht nur bei der Erprobung physischer Prototpyen, sondern auch schon frühzeitig bei Studien auf Fahrsimulatoren.
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Koh, Bong Su. "Adaptive inverse modeling of a shape memory alloy wire actuator and tracking control with the model." [College Station, Tex. : Texas A&M University, 2006. http://hdl.handle.net/1969.1/ETD-TAMU-1713.
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Joshi, Darshan Gajanan. "Magnetic quantum phase transitions: 1/d expansion, bond-operator theory, and coupled-dimer magnets." Doctoral thesis, Saechsische Landesbibliothek- Staats- und Universitaetsbibliothek Dresden, 2016. http://nbn-resolving.de/urn:nbn:de:bsz:14-qucosa-198634.
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In the study of strongly interacting condensed-matter systems controlled microscopic theories hold a key position. Spin-wave theory, large-N expansion, and $epsilon$-expansion are some of the few successful cornerstones. In this doctoral thesis work, we have developed a novel large-$d$ expansion method, $d$ being the spatial dimension, to study model Hamiltonians hosting a quantum phase transition between a paramagnet and a magnetically ordered phase. A highlight of this technique is that it can consistently describe the entire phase diagram of the above mentioned models, including the quantum critical point. Note that most analytical techniques either efficiently describe only one of the phases or suffer from divergences near the critical point. The idea of large-$d$ formalism is that in this limit, non-local fluctuations become unimportant and that a suitable product state delivers exact expectation values for local observables, with corrections being suppressed in powers of $1/d$. It turns out that, due to momentum summation properties of the interaction structure factor, all diagrams are suppressed in powers of $1/d$ leading to an analytic expansion. We have demonstrated this method in two important systems namely, the coupled-dimer magnets and the transverse-field Ising model.
Coupled-dimer magnets are Heisenberg spin systems with two spins, coupled by intra-dimer antiferromagnetic interaction, per crystallographic unit cell (dimer). In turn, spins from neighboring dimers interact via some inter-dimer interaction. A quantum paramagnet is realized for a dominant intra-dimer interaction, while a magnetically ordered phase exists for a dominant (or of the same order as intra-dimer interaction) inter-dimer interaction. These two phases are connected by a quantum phase transition, which is in the Heisenberg O(3) universality class. Microscopic analytical theories to study such systems have been restricted to either only one of the phases or involve uncontrolled approximations. Using a non-linear bond-operator theory for spins with S=$1/2$, we have calculated the $1/d$ expansion of static and dynamic observables for coupled dimers on a hypercubic lattice at zero temperature. Analyticity of the $1/d$ expansion, even at the critical point, is ensured by correctly identifying suitable observables using the mean-field critical exponents. This method yields gapless excitation modes in the continuous symmetry broken phase, as required by Goldstone\'s theorem. In appropriate limits, our results match with perturbation expansion in small ratio of inter-dimer and intra-dimer coupling, performed using continuous unitary transformations, as well as the spin-wave theory for spin-$1/2$ in arbitrary dimensions. We also discuss the Brueckner approach, which relies on small quasiparticle density, and derive the same $1/d$ expansion for the dispersion relation in the disordered phase. Another success of our work is in describing the amplitude (Higgs) mode in coupled-dimer magnets. Our novel method establishes the popular bond-operator theory as a controlled approach.
In $d=2$, the results from our calculations are in qualitative agreement with the quantum Monte Carlo study of the square-lattice bilayer Heisenberg AF spin-$1/2$ model. In particular, our results are useful to identify the amplitude (Higgs) mode in the QMC data.
The ideas of large-$d$ are also successfully applied to the transverse-field Ising model on a hypercubic lattice. Similar to bond operators, we have introduced auxiliary Bosonsic operators to set up our method in this case.
We have also discussed briefly the bilayer Kitaev model, constructed by antiferromagnetically coupling two layers of the Kitaev model on a honeycomb lattice. In this case, we investigate the dimer quantum paramagnetic phase, realized in the strong inter-layer coupling limit. Using bond-operator theory, we calculate the mode dispersion in this phase, within the harmonic approximation. We also conjecture a zero-temperature phase diagram for this model.
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Jerger, Dorit [Verfasser]. "Radar Forward Operator for Verification of Cloud Resolving Simulations within the COSMO Model / Dorit Jerger." Karlsruhe : KIT Scientific Publishing, 2014. http://www.ksp.kit.edu.
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Calin, Ovidiu, and Chang Der-Chen. "The geometry on a step 3 Grushin model." Universität Potsdam, 2004. http://opus.kobv.de/ubp/volltexte/2008/2672/.
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In this article we study the geometry associated with the sub-elliptic operator ½ (X²1 +X²2), where X1 = ∂x and X2 = x²/2 ∂y are vector fields on R². We show that any point can be connected with the origin by at least one geodesic and we provide an approximate formula for the number of the geodesics between the origin and the points situated outside of the y-axis. We show there are in¯nitely many geodesics between the origin and the points on the y-axis.
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Šemberová, Kateřina. "Management of the Enterprise and Environment." Master's thesis, Vysoká škola ekonomická v Praze, 2008. http://www.nusl.cz/ntk/nusl-4001.
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The contribution of acquisition of Veolia group with Czech water supply companies to the Czech Republic. The assessment of Veolia's influence to Czech environment, to quality of citizen's daylife and to economics of the Czech Republic. Comparison with other water service suppliyng companies.
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Wendland, Mitchel. "Shape from focus image processing approach based 3D model construction of manufactured part." Scholarly Commons, 2018. https://scholarlycommons.pacific.edu/uop_etds/3569.
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The purpose of this research is to develop a process and an algorithm to create a 3D model of the surface a part. This is accomplished using a single camera and a CNC machine as a movable stage. A gradient based focus measure operator written in MATLAB is used to process the images and to generate the surface model. The scopes of this research are image processing and surface model generation as well as verifying part accuracy. The algorithm is able to create a rough surface model of a photographed part, and with careful calibration in a limited number of scenarios has been used in checking part z dimensions.
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Perea-Estrada, Hugo. "Development, Verification, and Evaluation of a Solute Transport Model in Surface Irrigation." Diss., Tucson, Arizona : University of Arizona, 2005. http://etd.library.arizona.edu/etd/GetFileServlet?file=file:///data1/pdf/etd/azu%5Fetd%5F1322%5F1%5Fm.pdf&type=application/pdf.
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Sipola, E. (Erika). "Developing a business model for a micro operator in 5G environment in campus use case in Finland." Master's thesis, University of Oulu, 2017. http://urn.fi/URN:NBN:fi:oulu-201711293192.
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The approaching 5G technology is expected to offer new opportunities for business especially in the indoor networks. Researchers have estimated that a new actor, a micro operator could take some part of the traditional mobile network operators’ role in the future. This research takes a future-oriented coopetitive perspective and examines the micro operator within its coopetitive ecosystem in 5G environment in campus context. The research aims to identify possible future business model elements for the micro operator in the 5G campus environment.
This research is conducted with a qualitative anticipatory action research approach. The qualitative methodology facilitates the creation of fundamental understanding of the researched subject that is required. Anticipatory action learning combines future studies and action research. This corresponds well with the target to vision the future business models and creates new knowledge for organizational change. The empirical data was gathered through background interviews and a co-creational workshop. The knowledge developed in the workshop is not static but co-created by players from the micro operator’s ecosystem with various perspectives. The empirical data is analyzed from coopetitive, 4C and openness perspectives.
The results of the study show promise. Many possible ways to generate a new business model were identified in the study. Three potential service entities were recognized for the campus use case. In total three service entities possess fifteen individual business opportunities. From the coopetition perspective, most of these fifteen potential business opportunities lies on the creation of new markets but also on the efficiency in the resource utilization. From the 4C business model perspective, the potential is mainly located on the content and context levels. The micro operator is operating in the coopetitive ecosystem. Thus, some level of openness is anticipated. This kind of business model’s elements are the core and extensions. They can both be closed and operated by one company or they can be developed together within the ecosystem if the core or extensions or both are open.
The research offers insight for academics and practitioners. It contributes to the scarce literature related to the coopetitive business models of micro operators. The study depicts how coopetition enables creation and capture of additional value that could not be created without coopetition. Thus, the coopetition can be valuable as part of the individual company’s business model. However, coopetition can be demanding for the managers as they coordinate the company’s conflicting goals. The study presents various potential business models that managers can evaluate and utilize in practice.
The reliability and validity can not be used as measurements in future-oriented research. The quality of the research is measured by the probability based on trends, the plausibility based on events that could occur in the future and the preferability based on the future we would like to have. The quality of the research is also enhanced by transparency as the choices and the research process are explained in detail.
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Godderidge, Bernhard. "A phenomenological rapid sloshing model for use as an operator guidance system on liquefied natural gas carriers." Thesis, University of Southampton, 2009. https://eprints.soton.ac.uk/142869/.
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A concept for a non-intrusive sloshing guidance system based on a phenomenological Rapid Sloshing Model is proposed to reduce the operational risk of sloshing damage to LNG carriers. A numerical sloshing model is implemented in a commercial Navier-Stokes Computational Fluid Dynamics (CFD) code which uses a volume-of- fluid approach for the simulation of multi- fuid problems. The effect of spatial and temporal discretisation and turbulence is investigated using systematic variation. Dimensional analysis of the multiphase flow regime and examination of the relative velocity at the fluid interface show that an inhomogeneous multiphase model is appropriate for the simulation of a violent sloshing flow. This is conrmed by the good agreement with the experimental data of Hinatsu. The effect of fluid compressibility is investigated for sloshing impacts and a criterion based on wave propagation is developed to assess the importance of compressibility. When modelling sloshing with large air bubble entrainment, the choice of fluid compressibility model is shown to have a significant influence on pressure magnitude and frequency of oscillation required for structural assessment and a thermal energy model is required. The Rapid Sloshing Model (RSM) is based on the observation that the centre of mass of a sloshing fluid tends to follow a particular trajectory. Using a phenomenological modelling approach, the forces affecting the sloshing response are approximated with mathematical functions for restoring force, damping and sloshing impacts. Calculation times for the resulting equations are typically 0.1% of real time on a desktop PC. A case study of sloshing induced by periodic rotation and translation of two-dimensional longitudinal and transverse sections of membrane LNG tanks is carried out using RSM. RSM is set up using one CFD simulation not considered in the case study and the RSM solutions are then compared to the independent CFD solutions. The fluid momentum from RSM is usually within 5%{15% of the CFD solution for excitation at and near the first resonant period at a filling level near the critical depth. An irregular surge motion profile from an ITTC two-parameter spectrum is applied to the tank and the mean error from the RSM solution remains below 15% when using momentum and transverse force. When applied to sloshing with a 10% filling level excited by an irregular seaway a mean error of 9.6% is obtained. Compared to existing phenomenological modelling approaches the RSM methodology reduces the error by an order of magnitude in sloshing scenarios of practical interest. A non-intrusive sloshing guidance system based on the Rapid Sloshing Model which is suitable for installation on existing and newbuild LNG carriers can be implemented by applying motion data measured onboard to the RSM to provide operator guidance on the sloshing severity in partially filled LNG tanks. The RSM is set up for a particular LNG carrier with existing sloshing data from the design and class approval stages.
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Tora, Veronica. "Laplace operator on finite graphs and a network diffusion model for the progression of the Alzheimer disease." Master's thesis, Alma Mater Studiorum - Università di Bologna, 2014. http://amslaurea.unibo.it/7889/.
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Nella tesi viene descritto il Network Diffusion Model, ovvero il modello di A. Ray, A. Kuceyeski, M. Weiner inerente i meccanismi di progressione della demenza senile. In tale modello si approssima l'encefalo sano con una rete cerebrale (ovvero un grafo pesato), si identifica un generale fattore di malattia e se ne analizza la propagazione che avviene secondo meccanismi analoghi a quelli di un'infezione da prioni. La progressione del fattore di malattia e le conseguenze macroscopiche di tale processo(tra cui principalmente l'atrofia corticale) vengono, poi, descritte mediante approccio matematico. I risultati teoretici vengono confrontati con quanto osservato sperimentalmente in pazienti affetti da demenza senile. Nella tesi, inoltre, si fornisce una panoramica sui recenti studi inerenti i processi neurodegenerativi e si costruisce il contesto matematico di riferimento del modello preso in esame. Si presenta una panoramica sui grafi finiti, si introduce l'operatore di Laplace sui grafi e si forniscono stime dall'alto e dal basso per gli autovalori. Al fine di costruire una cornice matematica completa si analizza la relazione tra caso discreto e continuo: viene descritto l'operatore di Laplace-Beltrami sulle varietà riemanniane compatte e vengono fornite stime dall'alto per gli autovalori dell'operatore di Laplace-Beltrami associato a tali varietà a partire dalle stime dall'alto per gli autovalori del laplaciano sui grafi finiti.
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Marais, Mario Alphonso. "Social capital as a resource in the Village Operator model for rural broadband internet access and use." Thesis, University of Pretoria, 2016. http://hdl.handle.net/2263/60506.
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This study dealt with the issue of sustainability of ICT4D initiatives being a problem with few success stories (Heeks, 2002, Toyama, 2010). Many of these initiatives were planned and executed in a top-down fashion by large funders and governments, and these failures have stimulated the search for new strategies to achieve long-term sustainability.
One possible approach is to consider the different levels of systems that are involved. The reasons for failure lie inside the scope of a project, within the community itself, and outside the community in the larger socio-economic system which includes the economy. A systems approach with respect to the analysis of the sustainability (or lack thereof) of development initiatives was therefore adopted. The Choice Framework of Dorothea Kleine (2010) was used since it is a systemic approach, developed in the study of ICT4D initiatives, that embraces the complexity of engaging with development paradigms, societal structures and personal agency.
The research was done on a large South African government initiative, the Broadband-for-All (BB4All), community-based wireless mesh network project which aimed to provide a cost-effective way of enabling reliable broadband connectivity in rural areas. The project had two key aspects, the provision of a large-scale demonstrator of a wireless mesh network (WMN) as a broadband solution and the establishment of a Village Operator (VO) model to support access to and increase the use of the technology. The teachers and learners in more than 170 schools were the primary customers. Young people from local communities were trained as VOs to become local entrepreneurs (micro-enterprises) responsible for operating and supporting the BB4All service in their assigned cluster of schools and respective communities.
The research focus was the sustainability of the VOs. The Choice Framework was used to provide a context for the research regarding the role played by social resources (social capital) in contributing to the sustainability of the VO micro-enterprises. In-depth interviews were held with all but one of the 15 VOs in order to develop an understanding of their social capital and the influence thereof on them as entrepreneurs. The importance and usefulness of social capital in supporting sustainability at VO and initiative level was analysed. Three major themes emerged that were analysed in detail, namely, the role of social capital, community service and social entrepreneurship, as well as the development of networks of innovation.
At a theoretical level, the research reflected on implications of the findings for the role of social capital in the Choice Framework. At a practical level, considerations for using a social capital perspective in order to improve the conceptualisation, design, implementation and transfer of ICT4D initiatives for sustainability were developed.Thesis (PhD)--University of Pretoria, 2016.
Informatics
PhD
Unrestricted
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Ribbing, Jakob. "Covariate Model Building in Nonlinear Mixed Effects Models." Doctoral thesis, Uppsala : Acta Universitatis Upsaliensis, 2007. http://urn.kb.se/resolve?urn=urn:nbn:se:uu:diva-7923.
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Zeng, Yuefei [Verfasser], and K. D. [Akademischer Betreuer] Beheng. "Efficient Radar Forward Operator for Operational Data Assimilation within the COSMO-model / Yuefei Zeng. Betreuer: K. D. Beheng." Karlsruhe : KIT-Bibliothek, 2013. http://d-nb.info/1043756221/34.
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Pátek, Tomáš. "Sada testovacích úloh pro měření odezvy lidského operátora." Master's thesis, Vysoké učení technické v Brně. Fakulta elektrotechniky a komunikačních technologií, 2020. http://www.nusl.cz/ntk/nusl-413183.
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This master’s thesis deals with the design of a simulator for measuring the response of a human operator in the MATLAB program and the Simulink extension. The first part summarizes the theory of mathematical models of human operator, which is followed by a description of a simulator for response measurement with a graphical user interface. In the last part, the basic measurement of human operator response to different scenarios, comparison of quality of control for different operators and identification of model for individual operators are performed.
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Viljoen, Johannes Henning. "Modelling and optimal control of the market of a telecommunications operator." Diss., Pretoria : [s.n.], 2004. http://upetd.up.ac.za/thesis/available/etd-09152004-100823.
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Bansel, Gurvinder Singh. "Advanced operator splitting based semi-implicit spectral method to solve the binary and single component phase-field crystal model." Thesis, Brunel University, 2011. http://bura.brunel.ac.uk/handle/2438/5900.
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We present extensive testing in order to find the optimum balance among errors associated with time integration, spatial discretization, and splitting for a fully spectral semi implicit scheme of the phase field crystal model. The scheme solves numerically the equations of dissipative dynamics of the binary phase field crystal model proposed by Elder et al. [Elder et al, 2007]. The fully spectral semi implicit scheme uses the operator splitting method in order to decompose the complex equations in the phase field crystal model into sub-problems that can be solved more efficiently. Using the combination of non-trivial splitting with the spectral approach, the scheme leads to a set of algebraic equations of diagonal matrix form and thus easier to solve. Using this method developed by the BCAST research team we are able to show that it speeds up the computations by orders of magnitude relative to the conventional explicit finite difference scheme, while the costs of the pointwise implicit solution per timestep remains low. Comparing both the finite difference scheme used by Elder et al [Elder et al, 2007] to the spectral semi implicit scheme, we are also able to show that the finite differencing cannot compete with the spectral differencing in regards to accuracy. This is mainly due to numerical dissipation in finite differencing. In addition the results show that this method can efficiently be parallelized for distributed memory systems, where an excellent scalability with the number of CPUs. We have applied the semi-implicit spectral scheme for binary alloys to explore polycrystalline dendritic solidification. The kinetics of transformation has been analysed in terms of Johnson-Mehl-Avrami-Kolmogorov formalism. We show that Avrami plots are not linear, and the respective Avrami-Kolmogorov exponents (PAK) vary with the transformed fraction (or time). Using the semi-implicit spectral scheme we have been able to provide extensive numerical testing of methods in solving the single component case. This has been demonstrated by using unconditional time stepping with comparable simulations using conditional time stepping. We show the accuracy of the solution for unconditional time stepping is not compromised and furthermore computational efficiency can be significantly increased with the introduction of this scheme. Finally we have investigated how the composition of the initial liquid phase influences the eutectic morphology evolving during solidification. This is the first study that addresses this question using the dynamical density functional theory.
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Langer, Marcel [Verfasser], Dirk [Akademischer Betreuer] Söffker, and Birgit [Akademischer Betreuer] Vogel-Heuser. "Model-based operator guidance in interactive, semi-automated production processes / Marcel Langer. Gutachter: Birgit Vogel-Heuser. Betreuer: Dirk Söffker." Duisburg, 2014. http://d-nb.info/1064580920/34.
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Langer, Marcel Verfasser], Dirk [Akademischer Betreuer] [Söffker, and Birgit [Akademischer Betreuer] Vogel-Heuser. "Model-based operator guidance in interactive, semi-automated production processes / Marcel Langer. Gutachter: Birgit Vogel-Heuser. Betreuer: Dirk Söffker." Duisburg, 2014. http://d-nb.info/1064580920/34.
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Purfürst, Thomas. "Der Einfluss des Menschen auf die Leistung von Harvestersystemen." Doctoral thesis, Saechsische Landesbibliothek- Staats- und Universitaetsbibliothek Dresden, 2009. http://nbn-resolving.de/urn:nbn:de:bsz:14-qucosa-19722.
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Produktivitätsmodelle geben Auskunft darüber, welche Leistung mit einem bestimmten Verfahren unter konkreten Rahmenbedingungen zu erwarten ist. In der Forstwirtschaft sind sie für Planungen und Kalkulationen notwendig. In bisherigen forstlichen Produktivitätsmodellen für den Maschineneinsatz wurde der Faktor Mensch, welcher einen wichtigen, bisher jedoch weitestgehend unbekannten Einfluss auf die Leistung hat, vernachlässigt. Ziel der vorliegenden Untersuchung ist es daher, den menschlichen Einfluss auf die Leistung von Harvestersystemen quantitativ zu erfassen und ihn in Produktivitätsmodelle einzubauen. Die Untersuchungsgrundlage bilden Leistungsmessungen, die mit vier verschiedenen Datenerhebungsverfahren an bis zu 32 Fahrern erfolgten. Neben einer neu entwickelten, sensorgestützten, semiautomatischen Zeitstudienmessung fand die Auswertung von summarischen Bordcomputer-Bestandesdaten über einen Zeitraum von drei Jahren Anwendung. Weiterhin erfolgte die (Weiter-)Entwicklung eines standardisierten Parcourstests, welcher auf einer Freifläche durchgeführt wird sowie eine Beurteilung der Leistung der Harvesterfahrer durch Gutachter. Alle vier Verfahren wurden miteinander verglichen und auf ihre Treffsicherheit und Aussagefähigkeit hin überprüft. Dabei konnten signifikante Korrelationen zwischen allen vier Datenerhebungsverfahren nachgewiesen werden, was eine Umrechnung untereinander grundsätzlich zulässt. Im Rahmen dieser Untersuchungen konnte die Vermutung quantitativ bestätigt werden, dass große, signifikant unterschiedliche Leistungshergaben zwischen den verschiedenen Harvesterfahrern existieren. Dies gilt nicht nur für den Vergleich zwischen so genannten „unerfahrenen“ und „erfahrenen“ Maschinenführern. Auch zwischen schon lange auf den Erntemaschinen arbeitenden Fahrern ist ein Leistungsunterschied von bis zu 80% zu verzeichnen. Somit ist die Beachtung des Parameters „Mensch“ für präzise Produktivitätsmodelle zwingend erforderlich. Der ursprüngliche Lösungsansatz, ein allgemein gültiges Produktivitätsmodell zu entwickeln, in dem der Einfluss des Menschen berücksichtigt wird, wurde aufgrund von Informationsdefiziten sowie zu starken Unterschieden und Komplexität der vorhandenen Modelle verworfen. Mit dem neu gewählten Lösungsansatz, der die Bestimmung eines Leistungswertes für jeden Fahrer vorsieht, ist es nun möglich, ein beliebig erstelltes Produktivitätsmodell linear auf ein Basisniveau zu normieren. Die Multiplikation des normierten Modells mit dem Leistungswert eines Fahrers ermöglicht es, die wahrscheinlich von ihm zu erwartende Produktivität zu berechnen. Dieser Wert kann auf verschiedene Weisen erhoben werden. Als Ergebnis dieser Arbeit kann dafür der entwickelte, schnell und einfach durchzuführende Parcourstest empfohlen werden. Er erreicht eine ungefähre Treffgenauigkeit von ±10%. Die Untersuchungen wiesen des Weiteren aus, dass beim Harvestereinsatz unter einfachen Umwelt- und Geländebedingungen der Fahrereinfluss auf die Produktivität bei 37% liegt. Er stellt somit nach Baumvolumen des ausscheidenden Bestandes (46%) den zweitwichtigsten Einflussfaktor dar. Die Leistungshergabe des einzelnen Harvesterfahrers ist nicht immer gleich, sondern verändert sich über der Zeit (Lernkurve). Die gemessenen Lerngeschwindigkeiten variieren dabei zwischen den Harvesterfahrern sehr stark. Das Anlernen eines unerfahrenen Harvesterfahrers dauerte bei den untersuchten Probanden im Mittel neun Monate, was einer Minderleistung von ca. 24% über diesen Zeitraum entspricht. Die bisherigen angenommenen Modelle der Lernkurve konnten bestätigt werden. Darüber hinaus zeigten sich Tendenzen, dass die Leistung der Fahrer nach der Lernphase ein konstantes Leistungsniveau erreicht, allerdings bei einer hohen Fehlerabweichung. Durch die Beurteilung und Berücksichtigung der Leistungen der Fahrer steht der Forstwirtschaft ein Werkzeug zur Verfügung, mit dem man in Zukunft die erstellten Produktivitätsmodelle für den Harvestereinsatz genauer auf die jeweiligen individuellen Gegebenheiten des eigenen Betriebes anpassen kann. Die Übertragung des gewählten Lösungsansatzes auf weitere Forstmaschinen, die von Menschen bedient werden, sollte geprüft werdenProductivity models provide information about the expected performance of a given procedure under specific conditions. In forestry, they are essential to planning and cost estimation. In hitherto existing productivity models of forest machinery, however, the human being as an important yet mostly unknown factor influencing productivity has been disregarded. Therefore, the objectives of this study are the quantification of the human impact on the performance of forest harvesting systems and its integration into productivity models. The study is based on performance measurements collected using four different methods of data acquisition to monitor up to 32 machine operators: (i) a newly developed sensor-based semi-automatic time study, (ii) the extraction of on-board computer data accumulated over a 3-year period, (iii) an improved standardized machinery test course conducted in an open area, and (iv) the expert evaluation of operator performance. The four data acquisition methods were compared and tested for data accuracy and informational value. All correlations between data yielded by each of the four methods were significant, thus in principle allowing for data conversion between data rendered by different acquisition methods. The results of this study quantitatively corroborate the presumption of major, significantly different performances between harvester operators. This holds true not only for the comparison of so-called ‘inexperienced’ and ‘experienced’ machine operators, but also when exclusively comparing experienced operators with each other. A performance difference of up to 80% has been observed between individuals featuring long-term experience in operating harvesting machinery. The integration of the parameter ‘human being’ is thus an imperative for precise productivity models. The original aim of developing a general productivity model accounting for human influence had to be abandoned due to an information deficit, substantial differences between the existing models as well as their inherent complexity. Instead, the new approach of determining a performance indicator for each individual machine operator now allows for the linear standardisation of any productivity model. By multiplying the standardised model with the performance indicator of a particular operator the probable performance to be expected of this operator can be calculated. This value can be determined in various ways. Based on this study, the test course value can be recommended, which was explicitly developed for fast and simple assessment of operator performance and achieves an accuracy of ±10%. The study results show that under favourable environmental conditions and on easy terrain the influence of the machine operator on overall performance amounts to 37%. The human factor is thus second only to the average volume of harvested trees (46%) with respect to influencing performance. The performance of an individual harvester operator is not constant, but changes over time (learning curve). The measured rate of learning largely differed between operators. The initial training of an inexperienced harvester operator took on average nine months, which corresponds to a performance deficiency of approx. 24% throughout this time period. Hitherto developed models of learning curves were corroborated by the study results. Performance levels following the initial training period tended to remain constant over time, but were characterised by large error margins. The evaluation and consideration of operator performance presents a forest management tool which allows for future customization of existing productivity models of harvesting machinery to the specific conditions and economics of any individual forest enterprise. The extrapolation of the presented approach towards quantification and integration of machine operator performance to other human-operated forest machinery needs to be investigated in subsequent studies
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Dunne, Gerald V. "Deep inelastic scattering and the EMC effect /." Title page, contents and introduction only, 1986. http://web4.library.adelaide.edu.au/theses/09SM/09smd923.pdf.
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Kabir, MD Ahsan. "Techno-economic study of grid connected residential PV system with battery storage - A review of the Local System Operator (LSO) model." Thesis, KTH, Elektroteknisk teori och konstruktion, 2017. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-205594.
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The grid connected solar PV system with battery storage is one of the promising alternativeenergy solutions for electricity consumers. The Local System Operator (LSO) will be a newactor to operate its own energy system by integrating PV and battery system with other technicalsolutions. This thesis investigates the technical and economic viability of a grid connected PVsystem with battery storage in behind-the-meter approach for aggregated residential load toassess the LSO model for the present conditions in Sweden.The system model is developed using the System Advisory Model (SAM) – a simulationsoftware for renewable energy system analysis. The PV system model is designed using solarirradiation profile and fifty multi-dwelling aggregated residential load data from Sweden. Theappropriate design inputs of solar PV module, inverter and system loss are taken from previousstudies. The electricity price is analysed from the comparative study of Nord-pool wholesaleprice, market retail price and distribution grid tariffs. The financial metrics such as discountrate, inflation rate, system cost and currently available PV incentives are considered to make anaccurate model. To help with the assessment, three cases are formed; the first case representsonly the PV system and the other cases include storage - using a lithium-ion or lead-acid battery.This comparative study helps to determine the optimum PV and battery size at two differentlocations in Sweden.The optimum net present value (NPV) and profitability index (PI) is found at the 40 kW PVand 3 kWh battery system at Karlstad, Sweden. The optimum case is considered for furtherinvestigation to evaluate the system life time energy profile, electricity bill saving capabilityand battery performance. The system peak shaving potential is investigated by making twoother scenarios with higher battery capacity. Sensitivity analysis is also performed to assess thesystem’s technical and financial input parameters. The system capacity factor at the site locationis found as an influential parameter to the annual production and profitability. The optimumsize of PV system with a lithium-ion battery investment is found feasible for the LSO realimplementation only considering the current PV incentives and electricity price in Sweden. Thereport concludes with the assessment, the technical and economic feasibility of the studied PVand battery storage system profitability depends on the system site location, residential loadsize, consumer electricity cost and available PV incentives.solcellsystem (PV) med batterilagring är en lovande alternativenergilösning förslutkonsumenten. Den 'local system operator', LSO, blir en ny aktör som driver egetenergisystem genom att integrera PV- och batterisystem med andra tekniska lösningar. Dennaavhandling undersöker det tekniska och ekonomiska genomförbarhetet i ett nätanslutet PVsystem med batterilagring i 'bakom mätaren' scenario för aggregerade bostäder i ettflerbostadshus, för att urvärdera LSO modellen.Systemmodellen är utvecklat med 'system advisory model' (rådgivande modell), SAM, ettsimuleringsprogram för förnybara energisystem. PV systemparametrarna beräknas med hänsyntill väderprofiler och lastdata från Sverige. Lämpliga parametrar för solcellsmoduler, omriktareoch systemförluster tas från tidigare studier. Slutkonsumenternas elpriser analyseras frånjämförande studie av NordPool grosshandelspris, konsumentpris och distributionnätstariffer.Finansiella mått såsom system kostnad, rabatt och inflationstakten och tillgängliga incitamentför PV investeringar används för att göra modellen noggrannare. Tre fall undersöks; det förstarepresenterar systemet med bara PV, och de övriga fallen lägger till lagring, genom antingenlitiumjon eller bly-syre batterier. Denna jämförande studie är ett underlag för att bestämma denoptimala PV och batteristorleken för anläggninar på två olika område i Sverige.Den optimala netto nuvarande värde (NPV) och lönsamhet index (PI) är på 40 kW PV systemetoch 3 kWh batteri på Karlstad, Sverige. Ytterligare undersökning av detta fall används för attutvärdera energiprofilen under systemets livstid, möjlighet till minskad elräkning, och batterietsprestanda. Potential för utjämning av systemets topplast utreds genom att skapa två andrascenarier med högre batterikapacitet. Känslighetsanalys utförs också för att bedöma de tekniskaoch ekonomiska parametrarna. Den optimuma storleken på PV system med ett litium-jonbatterifinns rimligt för LSO riktiga genomförande med tanke på incitamenten. Simuleringsresultatenoch systemkonsekvenserna av LSO modellen diskuteras. Rapporten visar att den tekniska ochekonomiska genomförbarheten av det studerade PV systemet med litium-jon batteri beror påslutkonsumentelpriset, PV incitament och globala trender i kostnaderna försystemkomponenter, samt på valet av lämplig plats med en effektiv analys av väder profil ochsystemetförluster.
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Phillips, Michael James. "A random matrix model for two-colour QCD at non-zero quark density." Thesis, Brunel University, 2011. http://bura.brunel.ac.uk/handle/2438/5084.
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We solve a random matrix ensemble called the chiral Ginibre orthogonal ensemble, or chGinOE. This non-Hermitian ensemble has applications to modelling particular low-energy limits of two-colour quantum chromo-dynamics (QCD). In particular, the matrices model the Dirac operator for quarks in the presence of a gluon gauge field of fixed topology, with an arbitrary number of flavours of virtual quarks and a non-zero quark chemical potential. We derive the joint probability density function (JPDF) of eigenvalues for this ensemble for finite matrix size N, which we then write in a factorised form. We then present two different methods for determining the correlation functions, resulting in compact expressions involving Pfaffians containing the associated kernel. We determine the microscopic large-N limits at strong and weak non-Hermiticity (required for physical applications) for both the real and complex eigenvalue densities. Various other properties of the ensemble are also investigated, including the skew-orthogonal polynomials and the fraction of eigenvalues that are real. A number of the techniques that we develop have more general applicability within random matrix theory, some of which we also explore in this thesis.
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Uyanik, Meltem. "Analysis of Discrete Fractional Operators and Discrete Fractional Rheological Models." TopSCHOLAR®, 2015. http://digitalcommons.wku.edu/theses/1491.
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This thesis is comprised of two main parts: Monotonicity results on discrete fractional operators and discrete fractional rheological constitutive equations. In the first part of the thesis, we introduce and prove new monotonicity concepts in discrete fractional calculus. In the remainder, we carry previous results about fractional rheological models to the discrete fractional case. The discrete method is expected to provide a better understanding of the concept than the continuous case as this has been the case in the past. In the first chapter, we give brief information about the main results. In the second chapter, we present some fundamental definitions and formulas in discrete fractional calculus. In the third chapter, we introduce two new monotonicity concepts for nonnegative or nonpositive valued functions defined on discrete domains, and then we prove some monotonicity criteria based on the sign of the fractional difference operator of a function. In the fourth chapter, we emphasize the rheological models: We start by giving a brief introduction to rheological models such as Maxwell and Kelvin-Voigt, and then we construct and solve discrete fractional rheological constitutive equations. Finally, we finish this thesis by describing the conclusion and future work.
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Parent, Christine. "L'approche erc : un modele de donnees et une algebre de type entite relation." Paris 6, 1987. http://www.theses.fr/1987PA066568.
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Presentation des definitions formelles d'un modele de donnees, d'une algebre associee et des proprietes mathematiques de ses operateurs. Le modele propose est le plus general possible par rapport aux possibilites liees aux trois concepts de base de l'approche entite relation (type d'entite, type de relation et attribut), avec notamment des attributs a structure recursive et des valeurs doubles
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Huang, Jin. "Business Models for Mobile Media Services : A case study in China mainland market." Thesis, KTH, Skolan för informations- och kommunikationsteknik (ICT), 2012. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-121301.
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Mobile media OTT service such as mobile music and mobile video is believed to be the next big revenue driver for mobile operator’s mobile broadband business. The media industry is willing to take mobile distribution channel to increase the content value. In Europe, there are already several successful cooperation cases between online media service provider and mobile operator, such as Spotify and Telia. However, with more complicated market and business environment in China, the mobile media services are still under development with immature business models.This thesis report aims to identify the business models of mobile media services in Europe and China, and to give business solution and strategic recommendation after analysis on actors, business roles, resources and activities using several business model theories. Six interviews have been done with industrial people from mobile network operator, online media service provider and TV channel in Sweden and China. With Spotify and Telia cooperation as the major part of case study in Europe market, data was gathered through business intelligent reports and interviews in Sweden. Six elements of business model theory from Chesbrough & Rosenbloom are used to conduct business model analysis onTelia-Spotify case. The result shows that Spotify play a joint connection role between tons of content from music insustry and mobile connection provider Telia, delivering value of good user experience and brand. Telia put the value of network, billing capability and user resource in the partnership with Spotify and benefit from the differentiated mobile broadband service, in terms of incearsing customer experience and reducing churn rate. TV4 case is investigated to analyze thebusiness development of mobile video in Europe. The result shows that there are two obstacles when delivering TV content to mobile device from TV channel’s perspective. One is that there is no way to measure the advertisement rate on mobile device, the other is that it is difficult to do localized advertisement program on mobile network. In the business model analysis in China, actors from mobile operator, state-owned media group and Internet company are identified as well as their activities in mobile media service. ARA model theory is used to analyze the value network and give the clear map of different actors’relations. The result shows that mobile media service in China has different situation in platform development, partnership with labels, service provider organization property and revenue model. Chinese mobile operators as state-owned companies develop mobile media service platform ontheir own instead of cooperation with service provider to avoid political and finance risk. They have direct partnership with content provider and give 50% of media OTT service revenue to content provider. The pirate rate of music in China is high, which result in very little willingness to pay for the music streaming service. Internet companies can build freemium service model with both licensed music content and content from illegal aggregators on advertising revenue model. However in online video area, Chinese government have implement strict regulatory to protect the copyright of video content. The major part of online video service providers’ revenueis also advertising, but with only licensed video content. The main factor that makes the different business environment between Europe and China is that the state-owned economy force in China plays important role in mobile media area. State owned mobile operators take the most business roles in mobile media service, which makes the possibility to cooperate with Spotify-like Internet companies is low. The first patch 3G mobile licenses are only granted to eight state-owned media groups, which are the only possible content providers of mobile operators’ mobile video service. To address the problem of cooperation inbetween mobile operators and Internet companies, to setup joint venture is the recommended solution. High customer satisfied service platform should be developed to enlarge the value of service. The recognized service value will lower the piracy rate and make the subscription revenue model possible.
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Engh, Cameron Howard. "A See-ability Metric to Improve Mini Unmanned Aerial Vehicle Operator Awareness Using Video Georegistered to Terrain Models." Diss., CLICK HERE for online access, 2008. http://contentdm.lib.byu.edu/ETD/image/etd2664.pdf.
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Falk, Karolina, and Joel Forsberg. "Adapting to the Changes Enforced by EU’s Network Codes for Electricity : The Consequences for an Electricity Company from a Distribution System Operator’s Perspective." Thesis, Linköpings universitet, Energisystem, 2014. http://urn.kb.se/resolve?urn=urn:nbn:se:liu:diva-107079.
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To reach EU’s climate and energy target an integrated electricity market is considered to be required (Klessmann, et al., 2011; Boie, et al., 2014; Becker, et al., 2013). As a result the European Commission decided to form a set of rules, named the Network Codes, to create a single European market (ENTSO-E, 2013b). The Network Codes will affect Distribution- and Transmission System Operators, grid users and production units as well as all the other actors on the electricity market (Eurelectric, n.d.a). Concerns regarding what the Network Codes’ actual consequences are have been expressed within the line of business (Swedish Energy, 2013a). Therefore the purpose of this master’s thesis was to determine and furthermore illustrate the consequences the Network Codes will have, in current version, for a Swedish non-transmission system connected electricity company and determine what actions need to be taken. The purpose has been addressed by conducting interviews, document studies and by utilizing a change management model, the Intervention Strategy Model, introduced by Paton & McCalman (2000). The structured approach that is the nature of the model was used when determining the consequences the Network Codes enforce and what actions a non-transmission system connected electricity company has to take to cope with them. To further facilitate the determination of these actions this study was conducted on a non-transmission system connected electricity company, in this thesis named Electricity Company A. The investigation of the concerns expressed within the line of business illustrated that the concerns were diverse but a majority of them might be incorporated into either of the following groups, simulation models, demand side aggregator and information handling. Out of these groups information handling was by far the area of greatest concern with issues primarily connected to the Distribution System Operator. Consequently this thesis focused on the Distribution System Operator’s perspective. The analysis of the area of greatest concern, presented in two flow charts, clearly showed the increased amount of communication enforced by the Network Codes. This increased information handling results in numerous possible organisational consequences for the Distribution System Operator, for example might new systems be required and some existing systems be used with or without adaption. Furthermore, the extra workload could possibly be handled by the existing personnel, in some cases after complementary education, but it might also require new personnel. Finally the Network Codes open up for the possibility for the Distribution System Operator to define certain details which may be conducted individually or in cooperation with other Distribution System Operators. Which of these possible consequences that will affect a specific company is, however, dependent on its preconditions. The study on Electricity Company A reveals that the numerous actions required to handle the new communication were not as significant as the line of business might have feared. For Electricity Company A, primarily a new system is needed to handle the real-time values and some of the existing systems need to be updated. Additionally the combined extra work load might require extra personnel for Electricity Company A even though the individual work assignments are fairly small. The actions required should be fairly similar for companies of approximately equal size but might be more extensive for smaller non-transmission system connected electricity companies. All companies need, however, to conduct an individual analysis to determine which specific actions are required for them. The conclusions of this thesis aspired, and partly succeeded, to be generalizable on a European level. One example of this is the usage of the Intervention Strategy Model which proved applicable for determining which specific actions are required for all European electricity companies. Furthermore the concerns presented and the possible consequences of the increased information handling found, are generalizable but not complete for all European electricity companies. This thesis focused on one part of the complex Network Codes’ consequences and consequently further research is needed to fully understand the consequences for the electricity business in total.
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Gebhardt, René. "Unbounded operators on Hilbert C*-modules: graph regular operators." Doctoral thesis, Universitätsbibliothek Leipzig, 2016. http://nbn-resolving.de/urn:nbn:de:bsz:15-qucosa-213767.
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Let E and F be Hilbert C*-modules over a C*-algebra A. New classes of (possibly unbounded) operators t: E->F are introduced and investigated - first of all graph regular operators. Instead of the density of the domain D(t) we only assume that t is essentially defined, that is, D(t) has an trivial ortogonal complement. Then t has a well-defined adjoint. We call an essentially defined operator t graph regular if its graph G(t) is orthogonally complemented and orthogonally closed if G(t) coincides with its biorthogonal complement. A theory of these operators and related concepts is developed: polar decomposition, functional calculus. Various characterizations of graph regular operators are given: (a, a_*, b)-transform and bounded transform. A number of examples of graph regular operators are presented (on commutative C*-algebras, a fraction algebra related to the Weyl algebra, Toeplitz algebra, C*-algebra of the Heisenberg group). A new characterization of operators affiliated to a C*-algebra in terms of resolvents is given as well as a Kato-Rellich theorem for affiliated operators. The association relation is introduced and studied as a counter part of graph regularity for concrete C*-algebras.
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Sica, G. "Electron-electron and electron-phonon interactions in strongly correlated systems." Thesis, Loughborough University, 2013. https://dspace.lboro.ac.uk/2134/12194.
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In this work we investigate some aspects of the physics of strongly correlated systems by taking into account both electron-electron and electron-phonon interactions as basic mechanisms for reproducing electronic correlations in real materials. The relevance of the electron-electron interactions is discussed in the first part of this thesis in the framework of a self-consistent theoretical approach, named Composite Operator Method (COM), which accounts for the relevant quasi-particle excitations in terms of a set of composite operators that appear as a result of the modification imposed by the interactions on the canonical electronic fields. We show that the COM allows the calculation of all the relevant Green s and correlation functions in terms of a number of unknown internal parameters to be determined self-consistently. Therefore, depending on the balance between unknown parameters and self-consistent equations, exact and approximate solutions can be obtained. By way of example, we discuss the application of the COM to the extended t-U-J-h model in the atomic limit, and to the two-dimensional single-band Hubbard model. In the former case, we show that the COM provides the exact solution of the model in one dimension. We study the effects of electronic correlations as responsible for the formation of a plethora of different charge and/or spin orderings. We report the phase diagram of the model, as well as a detailed analysis of both zero and finite temperature single-particle and thermodynamic properties. As far as the single-band Hubbard model is concerned, we illustrate an approximated self-consistent scheme based on the choice of a two-field basis. We report a detailed analysis of many unconventional features that arise in single-particle properties, thermodynamics and system's response functions. We emphasize that the accuracy of the COM in describing the effects of electronic correlations strongly relies on the choice of the basis, paving the way for possible multi-pole extensions to the two-field theory. To this purpose, we also study a three-field approach to the single-band Hubbard model, showing a significant step forward in the agreements with numerical data with respect to the two-pole results. The role of the electron-phonon interaction in the physics of strongly correlated systems is discussed in the second part of this thesis. We show that in highly polarizable lattices the competition between unscreened Coulomb and Fröhlich interactions results in a short-range polaronic exchange term Jp that favours the formation of local and light pairs of bosonic nature, named bipolarons, which condense with a critical temperature well in excess of hundred kelvins. These findings, discussed in the framework of the so-called polaronic t-Jp model, are further investigated in the presence of a finite on-site potential U, coming from the competition between on-site Coulomb and Fröhlich interactions. We discuss the role of U as the driving parameter for a small-to-large bipolaron transition, providing a possible explanation of the BEC-BCS crossover in terms of the properties of the bipolaronic ground state. Finally, we show that a hard-core bipolarons gas, studied as a charged Bose-Fermi mixture, allows for the description of many non Fermi liquid behaviours, allowing also for a microscopic explanation of pseudogap features in terms of a thermal-induced recombination of polarons and bipolarons, without any assumption on preexisting order or broken symmetries.
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Nelson, Justin. "The Development of a Human Operator Informatic Model (HOIM) incorporating the Effects of Non-Invasive Brain Stimulation on Information Processing while performing Multi-Attribute Task Battery (MATB)." Wright State University / OhioLINK, 2016. http://rave.ohiolink.edu/etdc/view?acc_num=wright1461066834.
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Cordeiro, Sérgio Gustavo Ferreira. "Formulações do método dos elementos de contorno aplicadas à análise elástica e à fratura coesiva de estruturas compostas planas." Universidade de São Paulo, 2015. http://www.teses.usp.br/teses/disponiveis/18/18134/tde-08042015-162639/.
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O presente trabalho trata do desenvolvimento de formulações numéricas para avaliar o comportamento mecânico de estruturas compostas planas, no contexto de elasticidade linear e mecânica da fratura não linear. As formulações propostas são baseadas no Método dos Elementos de Contorno (MEC), por meio das representações integrais singular e hiper singular dos problemas elastostáticos. A técnica de multi-regiões é considerada para acoplar a interface de sólidos multifásicos. O MEC é uma técnica numérica robusta e precisa para analisar o fenômeno da fratura em sólidos. Esse método numérico apresenta uma natural redução na dimensionalidade do problema, tornando mais simples a modelagem das superfícies de fratura. Além disso, essa redução de dimensionalidade faz também com que o tratamento de interfaces materiais em estruturas compostas seja uma tarefa menos árdua. Com o uso da solução fundamental de Kelvin nas representações integrais, materiais isotrópicos podem ser considerados para constituir as estruturas compostas. Por outro lado, utilizando a solução fundamental de Cruse & Swedlow, também é possível lidar, de maneira geral, com materiais anisotrópicos em estruturas compostas. Nessas estruturas, as fraturas são assumidas como ocorrendo ao longo das interfaces e o comportamento não linear é introduzido pelo modelo coesivo de fratura, o qual é aplicável a materiais quase frágeis. Nessas análises, o sistema não linear de equações pode ser solucionado utilizando dois distintos algoritmos de resolução iterativa. O primeiro sempre leva em consideração a rigidez elástica da estrutura e é, portanto denominado Operador Constante (OC). Já o segundo é denominado Operador Tangente (OT), pois considera uma rigidez tangente à resposta estrutural não linear, o que resulta em melhores taxas de convergência em comparação ao OC. Como aplicações das formulações, estruturas compostas teóricas foram analisadas em regime elástico. Além disso, testes experimentais de fratura em espécimes de concreto e madeira também foram simulados. A comparação dos resultados com as referências demonstrou que, as formulações foram efetivas e precisas para avaliar respostas mecânicas de estruturas, seja em regime elástico linear ou nos testes de fratura quase frágil.The present work deals the development of numerical formulations to evaluate the mechanical behaviour of plane composed structures, in the context of linear elasticity and nonlinear fracture mechanics. The proposed formulations are based on the Boundary Element Method (BEM), through its classical singular and hyper singular integral equations. The multi-region technique is adopted to couple the interfaces of non-homogeneous multiphase bodies. The BEM is a robust and accurate numerical technique to analyse fracture phenomena in solids. This numerical method presents a mesh dimensionality reduction, which makes easier the modelling of cracks surfaces. Besides, this dimensionality reduction also makes the treatment of interfaces in composed structures a less complex task. Considering the use of Kelvin fundamental solutions at the integrals equations, isotropic materials can be represent as parts of the composed structures. On the other hand, using Cruse & Swedlow fundamental solution it is also possible to deal with general anisotropic materials. At the composed structures, cracks can propagate along the materials interfaces and the cohesive crack model is responsible for the nonlinear structural behaviour of the quasi-brittle failures. The nonlinear system of equations at the fracture analyses is solved using two different algorithms for iterative resolution. The first always takes into account the structure elastic strength and, hence it is called Constant Operator (CO). On the other hand, the second is denominated Tangent Operator (TO) due to the fact that it considers strengths at the tangent directions of the nonlinear structural response. Therefore, convergence rates are faster when compared with the CO. As applications, composed structures were analysed with the developed formulations in linear elastic range. In addition, experimental fracture testes performed in concrete and wood specimens were also analysed. The confront of obtained results with the reference ones show that, the formulation was effective and accurate to evaluate the mechanical responses of composed structures in linear elastic range, and also to perform nonlinear quasi-brittle fracture tests.
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Семенчук, Василь Миколайович, and Vasyl Semenchuk. "Методи та програмно-апаратні засоби оптимізаційних процесів на основі генетичних алгоритмів." Master's thesis, Тернопільський національний технічний університет імені Івана Пулюя, 2020. http://elartu.tntu.edu.ua/handle/lib/33351.
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Кваліфікаційна робота присвячена дослідженню генетичних алгоритмів як способу оптимізації, їх ефективності і трудомісткості. Для виконання була обрана задача комівояжера, оскільки вона дуже добре вивчена, має ефективні способи розв’язання, для того, щоб порівняти з отриманими результатами. Також однією з цілей даної роботи є вивчення поширення генетичних алгоритмів на модель з декількома взаємодіючими популяціями (міграції та острівну).
Основним інструментом для практичного дослідження було обрано середовище MATLAB, оскільки воно має багато вбудованих функцій і панелей інструментів для вирішення завдань генетичного програмування і їх паралельного виконання.Thesis deals with the study of genetic algorithms as a way of optimization, their efficiency and complexity. The Travelling Salesman Problem was taken into consideration as it is very well studied, has effective ways of the decision, in order to compare with the received results. Also, one of the aims of this work is to study the propagation of genetic algorithms to a model with several interacting populations (migration and island). The MATLAB environment was taken as the main tool for practical research, as it has many built-in functions and toolbars for solving problems of genetic programming and their parallel execution.
1 Аналітична частина. 2 Теоретична частина. 3. Практична частина. Розв’язок задачі комівояжера з використанням можливостей пакета MATLAB. 4 Охорона праці та безпека в надзвичайних ситуаціях
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Oliveira, Hugo Luiz. "Uma formulação alternativa do método dos elementos de contorno aplicada à análise da propagação de fissuras em materiais quase frágeis." Universidade de São Paulo, 2013. http://www.teses.usp.br/teses/disponiveis/18/18134/tde-30072013-092437/.
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Este trabalho trata da análise da propagação de fissuras, independente do tempo, em domínios bidimensionais utilizando uma formulação alternativa do método dos elementos de contorno (MEC). O MEC vem sendo utilizado com sucesso na análise de diversos problemas de engenharia. Considerando problemas de mecânica da fratura, o MEC é especialmente eficiente devido à redução da dimensionalidade de sua malha, o que permite a simulação do crescimento das fissuras sem as dificuldades do processo de remalhamento. Nesta pesquisa, desenvolvem-se formulações não lineares do MEC para a análise da propagação de fissuras em materiais quase frágeis. Nesses materiais, a zona de processo à frente da ponta da fissura introduz efeitos fisicamente não lineares no comportamento estrutural. Assim, para a simulação da presença da zona de processo, modelos não lineares são necessários. Classicamente a formulação dual do MEC é utilizada para modelar propagação de fissuras na quais equações singulares e hipersingulares são escritas para elementos definidos ao longo das faces das fissuras. O presente trabalho propõe uma segunda formulação utilizando um campo de tensões iniciais para a representação da zona coesiva. Nesta formulação, o termo de domínio da equação integral clássica do MEC é degenerado, de forma a atuar somente ao longo do caminho de crescimento das fissuras, sendo que esse procedimento dá origem a uma nova variável denominada dipolo, responsável por garantir o atendimento das condições de contorno. Em conjunto com essa nova formulação, se propõe o uso do operador tangente (OT), que é deduzido no trabalho, a fim de acelerar o processo de convergência da solução. Os resultados obtidos, por meio da formulação alternativa, são comparados tanto com dados experimentais quanto com o MEC dual, ambos disponíveis na literatura. As respostas encontradas foram satisfatórias no sentido de conseguir reproduzir o comportamento real da estrutura explorando as vantagens computacionais proporcionadas pelo OT.This work presents a time-independent crack propagation analysis, in two-dimensional domains, using an alternative boundary element method (BEM) formulation. BEM has been used successfully to analyze several engineering problems. Considering fracture mechanics problems, BEM is especially efficient due to its mesh reduction aspects, which allows the simulation of crack growth without remeshing difficulties. In this research, nonlinear BEM formulations are develop in order to analyze crack propagation in quasi-brittle materials. Considering these materials, the process zone ahead of the crack tip leads to nonlinear effects related to structural behavior. Thus, nonlinear models are required for simulating the presence of the process zone. Classically, the dual BEM is used for modeling the crack propagation, in which singular and hyper-singular equations are written for elements defined along the crack faces. This work proposes an alternative formulation using the initial stress field to represent the cohesive zone. In this formulation, the classic domain integral term is degenerated in order to be non-null only at the crack growth path. This procedure leads the creation of new variable called dipole, which is responsible for ensuring the compliance of the boundary conditions. In addition to this new formulation, it is proposed the use of the tangent operator (TO), which is derived in this work, in order to accelerate the convergence. The results obtained using the new formulation, are compared with experimental data and dual BEM results available in the literature. The responses were found satisfactory in reproducing the behavior of real structures exploiting the computational advantages provided by the TO.
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Litaiff, Fabian Cardoso. "Modelos de spins geometricamente frustrados: transição de fase e estruturas de platores." Universidade Federal de São Carlos, 2013. https://repositorio.ufscar.br/handle/ufscar/4963.
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Previous issue date: 2013-04-08Universidade Federal de Minas Gerais
This thesis presents a study of the magnetization plateau and the phenomenon of geometrical frustration in spin systems applied to lattices with triangular structure, as well as the results achieved by applying the differential operator technique of the Ising and Heisenberg models with external magnetic field applied to the easy magnetization axis z, their phase diagrams, behavior plateaus observed and analyzed according to the Haldane conjecture and appearance of plateaus presented by Oshikawa, Yamanaka and Affleck, and also to study the behavior of the magnetic susceptibility in order to verify the behavior of frustrated systems using the frustration factor f= θWC/TN to verify frustration encountered at various stages of the study models
Este trabalho apresenta um estudo da magnetização de platô e do fenômeno de frustração geométrica em sistemas de spins, aplicados às redes com estrutura triangular, bem como os resultados alcançados aplicando-se a técnica do operador diferencial a modelos de Ising e Heisenberg com campo magnético externo aplicado sobre o eixo fácil de magnetização z, seus diagramas de fases e comportamento de platôs observados e analisados segundo a conjectura de Haldane e a condição de aparecimento de platôs apresentada por Oshikawa, Yamanaka e Affleck, e ainda, o estudo do comportamento da susceptibilidade magnética com o objetivo de verificar o comportamento dos sistemas frustrados utilizando-se o fator de frustração f= θWC/TN para verificar a frustração nas diversas fases encontradas ao longo do estudo dos modelos.