To see the other types of publications on this topic, follow the link: The higher order mode.
Dissertations / Theses on the topic 'The higher order mode'
Create a spot-on reference in APA, MLA, Chicago, Harvard, and other styles
Consult the top 50 dissertations / theses for your research on the topic 'The higher order mode.'
Next to every source in the list of references, there is an 'Add to bibliography' button. Press on it, and we will generate automatically the bibliographic reference to the chosen work in the citation style you need: APA, MLA, Harvard, Chicago, Vancouver, etc.
You can also download the full text of the academic publication as pdf and read online its abstract whenever available in the metadata.
Browse dissertations / theses on a wide variety of disciplines and organise your bibliography correctly.
1
Gupta, Sanjeev. "Higher order approximation for combined mode heat transfer in building insulations." Thesis, Virginia Tech, 1988. http://hdl.handle.net/10919/43751.
Full textAbstract:
For heat transfer through building insulations such as fiberglass, radiation and conduction are important modes of heat transfer. Moreover, materials like fiberglass scatter radiation in a highly anisotropic manner. The equations for heat transfer by simultaneous conduction and radiation are a coupled pair, one of which is of the nonlinear integrodifferential type. Exact solution for transient heat transfer in this case is not available, and the approximate solution available is the two-flux model. The two-flux model does not give good results for transient, combined mode heat transfer, through an absorbing, emitting, and anisotropically scattering medium. In this thesis a higher order approximate solution has been developed. It is found that this model gives appreciably better results than the two-flux model.
Master of Science
2
Swikir, Abdalla M. Lamen. "CHATTERING ANALYSIS OF THE SYSTEM WITH HIGHER ORDER SLIDING MODE CONTROL." The Ohio State University, 2015. http://rave.ohiolink.edu/etdc/view?acc_num=osu1444243591.
Full text
3
Pukdeboon, Chutiphon. "Optimal Higher-Order Sliding Mode Controller Designs for Spacecraft Attitude Manoeuvres." Thesis, University of Sheffield, 2009. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.521820.
Full text
4
Neatherway, Robin Philip. "Higher-order model checking with traversals." Thesis, University of Oxford, 2014. http://ora.ox.ac.uk/objects/uuid:240bd517-1582-45f9-86c3-eb30f85757de.
Full textAbstract:
Higher-order recursion schemes are a powerful model of functional computation that grew out of traditional recursive program schemes and generalisations of grammars. It is common to view recursion schemes as generators of possibly-infinite trees, which Ong showed to have a decidable monadic second order theory and opened the door to applications in verification. Kobayashi later presented an intersection type characterisation of the model checking problem, on which most subsequent applied work is based. In recent work, recursion schemes have been considered to play a role similar to Boolean programs in verification of first-order imperative programs: a natural target for abstraction of programs with very large or infinite data domains. In this thesis we focus on the development of model checking algorithms for variants of recursion schemes. We start our contributions with a model checking algorithm inspired by the fully abstract game semantics of recursion schemes, but specified as a goal-directed approach to intersection type inference, that offers a unification of the views of Ong and Kobayashi. We build on this largely theoretical contribution with two orthogonal extensions and practical implementations. First, we develop a new extension of recursion schemes: higher-order recursion schemes with cases, which add non-determinism and a case construct operating over a finite data domain. These additions provide us with a more natural and succinct target for abstraction from functional programs: encoding data using functions inevitably results in an increase in the order and arity of the scheme, which have a direct impact on the worst-case complexity of the problem. We characterise the model checking problem using a novel intersection and union type system and give a practical algorithm for type inference in this system. We have carried out an empirical evaluation of the implementation --- the tool TRAVMC --- using a variety of problem instances from the literature and a new suite of problem instances derived via an abstraction-refinement procedure from functional programs. Second, we extend our approach from safety properties to all properties expressible in monadic second order logic using alternating parity tree automata as our specification language. We again provide an implementation and an empirical evaluation, which shows that despite the challenges accompanying liveness properties our tool scales beyond the current state of the art.
5
Williams, Brett W. "Higher-order modes in free electron lasers." Thesis, Monterey, Calif. : Springfield, Va. : Naval Postgraduate School ; Available from National Technical Information Service, 2005. http://library.nps.navy.mil/uhtbin/hyperion/05Sep%5FWilliams.pdf.
Full text
6
Liu, Jianxing. "Contributions to Adaptative Higher Order Sliding Mode Observers : Application to Fuel Cell an Power Converters." Thesis, Belfort-Montbéliard, 2014. http://www.theses.fr/2014BELF0232/document.
Full textAbstract:
Les systèmes piles à combustible de type PEM pour des applications de transport reposent sur un ensemble d’auxiliaires (stockage d’hydrogène, compresseur d’air, convertisseur de puissance, humidificateur, etc) qui assurent le bon fonctionnement du système pile. La mise en place d’observateurs permet de disposer d’un outil pour reconstruire les états non mesurés de ce système; cela permet de mettre en place un contrôle par retour de sortie en vue d’optimiser les performances du système pile et ainsi d'améliorer la détection et l’isolation de défauts (FDI). Cette thèse est basée sur l’étude et la synthèse d'observateurs adaptatifs par mode glissant d’ordre supérieur, pour deux principaux auxiliaires de la pile que sont, le système d'alimentation en air et les convertisseurs de puissance associés à la pile. La première partie de la thèse est consacrée à la synthèse d’observateurs pour la reconstruction des états et à la détection et l’isolation des défauts sur le système d’alimentation en air de la PEMFC. Dans un premier temps, un observateur algébrique par mode glissant d’ordre supérieur est synthétisé pour la reconstruction de la pression partielle de l'oxygène et de l'azote. Dans un deuxième temps, un nouvel observateur adaptatif par mode glissant d’ordre deux est synthétisé pour assurer l'observation simultanée des états, l'identification des paramètres, la surveillance et la reconstruction de défaut dans le circuit d’air. Les performances des observateurs proposées ont été validées grâce à un simulateur Hardware-In-Loop (HIL) du système pile à combustible.Dans la deuxième partie, nous nous sommes intéressés à l’élaboration d’observateurs et de commande par retour de sortie pour les convertisseurs associé au système pile dans une application transport. Ainsi, une commande novatrice par mode glissant d’ordre deux, de type retour de sortie, a été élaborée pour le convertisseur AC/DC. Dans un second temps, un observateur de type modes glissants d’ordre 2 adaptatif est synthétisé pour un convertisseur de type multicellulaireAutomotive PEM Fuel Cell systems rely upon a set of auxiliary systems for proper operation, such as humidifier, air-feed compressor, power converter etc. The internal physical states of the latter are often unmeasurable, yet required for their precise control. Observers provide a means of obtaining the unmeasured states of these auxiliary systems for feedback control, optimal energy consumption and Fault Diagnosis and Isolation (FDI). This thesis is based on higher order sliding mode observer design studies for two major PEMFC auxiliary systems found in modern automobiles, the air-feed system and the power electronics system.The first part is focused on robust observation and FDI of the PEMFC air-feed systems. Sliding mode observer design and their applications to FDI have been studied in detail for this purpose and the key observation problems in this system have been identified. Based on this study, two solutions are proposed, a sliding mode algebraic observer for oxygen and nitrogen partial pressures and a novel robust adaptive-gain Second Order Sliding Mode (SOSM) observer based FDI for simultaneous state observation, parameter identification, health monitoring and fault reconstruction of the PEMFC air-feed system. The performance of the proposed observers has been validated on an instrumented Hardware-In-Loop (HIL) test bench.The observation and output feedback control problems of different power electronic converters, commonly found in fuel cell vehicles, are addressed in the next part. Robust output feedback SOSM control for three phase AC/DC converters have been presented. A robust SOSM observer for multi-cell converters has also been designed. The performance of all these designs has been demonstrated through a multi-rate simulation approach. The results highlight the robustness of the observers and controllers against parametric uncertainty, measurement noise and external disturbance
7
James, Michael Mark. "Fundamental Studies of the Herschel-Quinke Tube Concept with Mode Measurements." Thesis, Virginia Tech, 2003. http://hdl.handle.net/10919/35862.
Full textAbstract:
A fundamental study of the Herschel-Quincke (HQ) tube concept for the reduction of noise in circular ducts is presented here. Recent testing of the Herschel-Quincke tube concept on the Pratt-Whitney JT15D and AlliedSignal TFE731-60 engines showed the potential for the practical application of this approach. A model of the HQ-system has been developed to aid in the design of the system tested. The model has revealed new noise control mechanisms associated to the implementation of multiple HQ-waveguides in a duct in the presence of higher order modes. However, the practical nature of these engine facilities results in limitations with regard to the fundamental research knowledge that could be gained from testing in a more controlled laboratory environment.
A series of experiments was conducted at the NASA Langley Research Center 0.30 m ducted fan test facility where detailed modal measurements were performed. The main goals of this research endeavor were to evaluate the accuracy of the previously developed theoretical model and provide insight into the noise control mechanisms. Experiments were performed with different disturbance mode structures, number of HQ tubes and arrays, and axial positions. The modes in the duct were generated with an array of acoustic drivers (no flow case) and measured with logarithmically spaced circumferential and helical microphone arrays located on the duct wall. The modal amplitudes of the incident, transmitted, and reflected modes in the duct were determined from the microphone measurements. This allowed for the comparison of analytical and experimental modal amplitudes, modal powers, total power, and reductions.
The results of this study provide insight into the three noise control mechanisms associated with this approach: reflection, circumferential scattering, and radial scattering. Comparison with the experimental results shows that the model accurately predicts the sound power attenuation except near the cut-off frequency of the modes where it tends to overestimate the attenuation. The effect of the number of tubes in the array and its axial position was also evaluated. Overall, the results of this study validate the general modeling approach for the HQ tube concept.Master of Science
8
Kowalski, Elizabeth J. (Elizabeth Joan). "Miter bend loss and higher order mode content measurements in overmoded millimeter-wave transmission lines." Thesis, Massachusetts Institute of Technology, 2010. http://hdl.handle.net/1721.1/62444.
Full textAbstract:
Thesis (S.M.)--Massachusetts Institute of Technology, Dept. of Electrical Engineering and Computer Science, 2010.Cataloged from PDF version of thesis.
Includes bibliographical references (p. 119-121).
High power applications require an accurate calculation of the losses on overmoded corrugated cylindrical transmission lines. Previous assessments of power loss on these lines have not considered beam polarization or higher order mode effects. This thesis will develop a theory of transmission that includes the effect of linearly polarized higher order modes on power loss in overmoded corrugated transmission line systems. This thesis derives the linearly polarized basis set of modes for corrugated cylindrical waveguides. These modes are used to quantify the loss in overmoded transmission line components, such as a gap in waveguide or a 900 miter bend. The dependence of the loss in the fundamental mode on the phase of higher order modes (HOMs) was investigated. In addition, the propagation of a multi-mode beam after the waveguide was quantified, and it was shown that if two modes with azimuthal (m) indices that differ by one propagate in the waveguide, the resultant centroid and the tilt angle of radiation at the guide end are related through a constant of the motion. These theoretical calculations are useful for high-power applications, such as the electron cyclotron heating in plasma fusion reactors. In addition, this thesis develops a low-power S-Parameter Response (SPR) technique to accurately measure the loss in ultra-low loss overmoded waveguide components. This technique is used to measure the loss of components manufactured to ITER (an experimental fusion reactor) specifications, operated at 170 GHz with a diameter of 63.5 mm and quarter-wavelength corrugations. The loss in a miter bend was found to be 0.022+0.08 dB. This measurement is in good agreement with theory, which predicts 0.027 dB loss per miter bend, and past measurements [18]. The SPR was used to measure the loss in a gap of waveguide and the results were in good agreement with the well-established theoretical loss due to gap, which demonstrates the accuracy of the SPR technique. For both of these measurements, a baseline analysis determined the effects of a small percentage (1-2%) of higher order modes in the system.
by Elizabeth J. Kowalski.
S.M.
9
Lombardi, Paolo. "Generic wind estimation and compensation based on residual generators and higher-order sliding mode schemes." Master's thesis, Alma Mater Studiorum - Università di Bologna, 2016. http://amslaurea.unibo.it/10662/.
Full textAbstract:
This master thesis proposes a solution to the approach problem in case of unknown severe microburst wind shear for a fixed-wing aircraft, accounting for both longitudinal and lateral dynamics. The adaptive controller design for wind rejection is also addressed, exploiting the wind estimation provided by suitable estimators. It is able to successfully complete the final approach phase even in presence of wind shear, and at the same time aerodynamic envelope protection is retained. The adaptive controller for wind compensation has been designed by a backstepping approach and feedback linearization for time-varying systems. The wind shear components have been estimated by higher-order sliding mode schemes. At the end of this work the results are provided, an autonomous final approach in presence of microburst is discussed, performances are analyzed, and estimation of the microburst characteristics from telemetry data is examined.
10
Goodell, Brian Carpenter, and Brian Carpenter Goodell. "Probing Intracavity Plasma Dynamics with Higher-Order Transverse Modes." Thesis, The University of Arizona, 2017. http://hdl.handle.net/10150/625686.
Full textAbstract:
Extreme ultraviolet (XUV) frequency combs exhibit promise for enabling high-precision spectroscopic measurements of myriad chemical species for the first time. Coherent XUV radiation can be generated through high harmonic generation (HHG) in femtosecond enhancement cavities. HHG efficiency is limited by nonlinear phase shifts induced by residual intracavity plasma. The goal of this work is to gain insight regarding plasma dynamics in order to allay the detrimental effects of plasma interactions. Our approach is to conduct simulations of cavity pump-probe experiments by probing with higher-order transverse modes. We propose methods for estimating spatial plasma profiles, gas jet velocities, and the plasma recombination coefficient based on measurements of plasma-induced phase shifts. Beam distortion due to plasma interaction is analyzed and used as another reference for plasma dynamics.
11
Liu, Fang-Jou. "A higher-order moment model for multiport circuits /." Diss., Connect to a 24 p. preview or request complete full text in PDF format. Access restricted to UC campuses, 1999. http://wwwlib.umi.com/cr/ucsd/fullcit?p9930902.
Full text
12
Ahlkrona, Josefin. "Implementing Higher Order Dynamics into the Ice Sheet Model SICOPOLIS." Thesis, Uppsala universitet, Avdelningen för teknisk databehandling, 2011. http://urn.kb.se/resolve?urn=urn:nbn:se:uu:diva-146947.
Full textAbstract:
Ice sheet modeling is an important tool both for reconstructing past ice sheets and predicting their future evolution, but is complex and computationally costly. It involves modeling a system including the ice sheet, ice shelves and ice streams, which all have different dynamical behavior. The governing equations are non-linear, and to capture a full glacial cycle more than 100,000 years need to be simulated. To reduce the problem size, approximations of the equations are introduced. The most common approximation, the Shallow Ice Approximation (SIA), works well in the ice bulk but fails in e.g. the modeling of ice streams and the ice sheet/ice shelf coupling. In recent years more accurate models, so-called higher order models, have been constructed to address these problems. However, these models are generally constructed in an ad hoc fashion, lacking rigor. In this thesis, so-called Second Order Shallow Ice Approximation (SOSIA) equations for pressure, vertical shear stress and velocity are implemented into the ice sheet model SICOPOLIS. The SOSIA is a rigorous model derived by Baral in 1999 [3]. The numerical solution for a simple model problem is compared to an analytical solution, and benchmark experiments, comparing the model to other higher order models, are carried out. The numerical and analytical solution agree well, but the results regarding vertical shear stress and velocity differ from other models. It is concluded that there are problems with the model implemented, most likely in the treatment of the relation between stress and strain rate.
13
Tahoumi, Elias. "New robust control schemes linking linear and sliding mode approaches." Thesis, Ecole centrale de Nantes, 2019. http://www.theses.fr/2019ECDN0056.
Full textAbstract:
Ce travail de thèse porte sur la conception des lois de commande pour des systèmes non linéaires, incertains et perturbés; ces lois de commande sont basées à la fois sur des approches par mode glissant, et sur des techniques linéaires. Les commandes par mode glissant (notamment d’ordre supérieur) sont connues pour leur robustesse face aux perturbations et incertitudes ainsi que pour leurs performances en terme de précision. Cependant, elles sont énergivores. Le retour d’état linéaire est connu pour être une commande lisse et à faible consommation d’énergie, mais il est très sensible aux perturbations et incertitudes. Le premier objectif de cette thèse est le développement de lois de commande présentant les avantages à la fois de la commande par mode glissant (robustesse et précision) et du retour d'état linéaire (faible consommation d'énergie). Le deuxième objectif est de montrer l’applicabilité des méthodes proposées aux systèmes physiques réels, notamment le banc électropneumatique de LS2N. Des applications sont également effectuées sur un système éolienThis work deals with the design of control laws for nonlinear, uncertain and perturbed systems based on sliding mode control and linear state feedback. Sliding mode control is known for its robustness versus perturbations and uncertainties as well as high accuracy tracking; however, it is high energy consuming. The linear state feedback is known to be a smooth control and low energy consuming, but it is highly sensitive to perturbations and uncertainties. The first objective of this thesis is the development of control laws that have the advantages of both sliding mode control (robustness and accuracy) and linear state feedback (low energy consumption). The second objective is to show the applicability of the proposed methods to real physical systems, notably the LS2N electropneumatic bench. Applications are also made on a wind system physical systems, notably the LS2N electropneumatic bench. Applications are also made on a wind system
14
Kord, Ahmad Farzaneh. "Higher order corrections in the minimal supersymmetric standard model." Thesis, University of Liverpool, 2005. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.420728.
Full text
15
Grellois, Charles. "Semantics of linear logic and higher-order model-checking." Sorbonne Paris Cité, 2016. http://www.theses.fr/2016USPCC024.
Full textAbstract:
Dans cette thèse, nous envisageons des problèmes de model-checking d'ordre supérieur à l'aide d'approches issues de la sémantique et de la logique. Le model-checking d'ordre supérieur étudie la vérification de propriétés, exprimées en logique monadique du second ordre, sur des arbres infinis générés par une classe de systèmes de réécriture appelés schémas de récursion d'ordre supérieur. Ces systèmes sont équivalents au lambda-calcul simplement typé avec récursion, et peuvent donc être étudiés à l'aide d'outils sémantiques. Plus précisément, l'objet de cette thèse est de relier le model-checking d'ordre supérieur à une série de concepts de premier plan en sémantique contemporaine, tels que la logique linéaire et sa sémantique relationnelle, la logique linéaire indexée, les lois distributives entre comonades, les comonades paramétrées et la logique tensorielle. Nous verrons que ces concepts contribuent de façon particulièrement naturelle à l'étude du model-checking d'ordre supérieur. Notre approche débute par une étude du système de types intersection de Kobayashi et Ong, qui permet de typer un schéma de récursion d'ordre supérieur avec les états d'un automate donné encodant une formule de la logique monadique du second ordre. Le schéma admet pour type l'état initial de l'automate si et seulement si l'arbre infini qu'il représente satisfait la propriété encodée par l'automate. En dépit de cette adéquation, le système de types de Kobayashi et Ong a été pensé indépendamment de la connexion existant entre les types intersections et les modèles de la logique linéaire, relation observée par Bucciarelli, Ehrhard, de Carvalho et Terui. Nous avons donc cherché à relier ces deux domaines. Notre analyse nous a permis de définir un système de types intersection dérivé de celui de Kobayashi et Ong, capturant lui aussi le model-checking d'ordre supérieur de façon adéquate. Contrairement au système original, notre système est formulé de façon modale, et correspond à une sémantique finitaire de la logique linéaire obtenue en composant la modalité exponentielle usuelle avec une comonade colorant les formules. Nous équipons cette sémantique de la logique linéaire avec un opérateur de point fixe inductif-coinductif, et obtenons ainsi un modèle du lambda-calcul avec récursion dans lequel l'interprétation d'un schéma de récursion d'ordre supérieur est l'ensemble des états depuis lesquels l'arbre infini qu'il représente est accepté. La finitude de la sémantique nous permet de donner de nouvelles preuves de plusieurs résultats de décidabilité pour des problèmes de model-checking d'ordre supérieur, dont le problème de la sélection formulé récemment par Carayol et Serre. La sémantique finitaire que nous définissons est inspirée du théorème d'écrasement extensionnel d'Ehrhard, qui montre que l'écrasement extensionnel du modèle relationnel de la logique linéaire correspond à sa sémantique finitaire donnée par le modèle de Scott. Ce résultat nous permet de définir dans un premier temps la comonade de coloration et l'opérateur de point fixe inductif-coinductif dans une sémantique quantitative correspondant à une variante infinie (et non-continue) du modèle relationnel de la logique linéaireThis thesis studies problems of higher-order model-checking from a semantic and logical perspective. Higher-order model-checking is concerned with the verification of properties expressed in monadic second-order logic, specified over infinite trees generated by a class of rewriting systems called higher-order recursion schemes. These systems are equivalent to lambda-terms with recursion, and can therefore be studied using semantic methods. The more specific purpose of this thesis is to connect higher-order model-checking to a series of advanced ideas in contemporary semantics, such as linear logic and its relational semantics, indexed linear logic, distributive laws between comonads, parametric comonads and tensorial logic. As we will see, all these ingredients meet and combine surprisingly well with higher-order model-checking. The starting point of our approach is the study of the intersection type system of Kobayashi and Ong. This intersection type system enables one to type a higher-order recursion scheme with states of a given automaton, associated with a formula of monadic second-order logic. The recursion scheme is typable with the initial state of the automaton if and only if the infinite tree it represents satisfies the formula of interest. In spite of this soundness-and-completeness result, the original type system by Kobayashi and Ong was not designed with the connection between intersection types and models of linear logic observed by Bucciarelli, Ehrhard, de Carvalho and Terui in mind. Our work has thus been to connect these two fields. Our analysis leads us to the definition of an alternative intersection type system, which enjoys a similar soundness-and-completeness theorem with respect to higher-order model-checking. In contrast to the original type system by Kobayashi and Ong, our modal formulation is the proof-theoretic counterpart of a finitary semantics of linear logic, obtained by composing the traditional exponential modality with a coloring comonad. We equip the semantics of linear logic with an inductive-coinductive fixpoint operator. We obtain in this way a model of the lambda-calculus with recursion in which the interpretation of a higher-order recursion scheme is the set of states from which the infinite tree it represents is accepted. The finiteness of the semantics enables us to reestablish several results of decidability for higher-order model-checking problems, among which the selection problem recently formulated and proved by Carayol and Serre. This finitary semantics are inspired from the extensional collapse theorem of Ehrhard, who shows that the relational semantics of linear logic collapses extensionally to the finitary semantics provided by Scott lanices. For that reason, we start in a preliminary approach to define the coloring comonad and the inductive-coinductive fixpoint operator in the quantitative semantics provided by an infinitary (and non-continuous) version of the relational model of linear logic
16
Walter, Sebastian. "Structured higher-order algorithmic differentiation in the forward and reverse mode with application in optimum experimental design." Doctoral thesis, Humboldt-Universität zu Berlin, Mathematisch-Naturwissenschaftliche Fakultät II, 2012. http://dx.doi.org/10.18452/16514.
Full textAbstract:
In dieser Arbeit werden Techniken beschrieben, die es erlauben (höhere) Ableitungen und Taylorapproximationen solcher Computerprogramme effizient zu berechnen. Auch inbesondere dann, wenn die Programme Algorithmen der numerischen linearen Algebra (NLA) enthalten. Im Gegensatz zur traditionellen algorithmischen Differentiation (AD), bei der die zugrunde liegenden Algorithmen um zusätzliche Befehlere erweitert werden, sind in dieser Arbeit die Zerlegungen durch definierende Gleichungen charakterisiert. Basierend auf den definierenden Gleichungen werden Strukturausnutzende Algorithmen hergeleitet. Genauer, neuartige Algorithmen für die Propagation von Taylorpolynomen durch die QR, Cholesky und reell-symmetrischen Eigenwertzerlegung werden präsentiert. Desweiteren werden Algorithmen für den Rückwärtsmodus der AD hergeleitet, welche im Wesentlichen nur die Faktoren der Zerlegungen benötigen. Im Vergleich zum traditionellen Ansatz, bei dem alle Zwischenergebnisse gespeichert werden, ist dies eine Reduktion von O(N^3) zu O(N^2) für Algorithmen mit O(N^3) Komplexität. N ist hier die Größe der Matrix. Zusätzlich kann bestehende, hoch-optimierte Software verwendet werden. Ein Laufzeitvergleich zeigt, dass dies im Vergleich zum traditionellen Ansatz zu einer Beschleunigung in der Größenordnung 100 führen kann. Da die NLA Funktionen als Black Box betrachtet werden, ist desweiteren auch der Berechnungsgraph um Größenordnungen kleiner. Dies bedeutet, dass Software, welche Operator Overloading benutzt, weniger Overhead hervorruft und auch weniger Speicher benötigt.This thesis provides a framework for the evaluation of first and higher-order derivatives and Taylor series expansions through large computer programs that contain numerical linear algebra (NLA) functions. It is a generalization of traditional algorithmic differentiation (AD) techniques in that NLA functions are regarded as black boxes where the inputs and outputs are related by defining equations. Based on the defining equations, structure-exploiting algorithms are derived. More precisely, novel algorithms for the propagation of Taylor polynomials through the QR, Cholesky,- and real-symmetric eigenvalue decomposition are shown. Recurrences for the reverse mode of AD, which require essentially only the returned factors of the decomposition, are also derived. Compared to the traditional approach where all intermediates of an algorithm are stored, this is a reduction from O(N^3) to O(N^2) for algorithms with O( N^3) complexity. N denotes the matrix size. The derived algorithms make it possible to use existing high-performance implementations. A runtime comparison shows that the treatment of NLA functions as atomic can be more than one order of magnitude faster than an automatic differentiation of the underlying algorithm. Furthermore, the computational graph is orders of magnitudes smaller. This reduces the additional memory requirements, as well as the overhead, of operator overloading techniques to a fraction.
17
Maddali, Ramakanth. "Parametric studies of circular expansion chambers using four-pole matrix approach while considering higher order mode effects." University of Cincinnati / OhioLINK, 2011. http://rave.ohiolink.edu/etdc/view?acc_num=ucin1298044625.
Full text
18
Zhang, Pei. "Beam position diagnostics with higher order modes in third harmonic superconducting accelerating cavities." Thesis, University of Manchester, 2013. https://www.research.manchester.ac.uk/portal/en/theses/beam-position-diagnostics-with-higher-order-modes-in-third-harmonic-superconducting-accelerating-cavities(587aa24b-8adc-4bc6-8f5c-475aa0028d06).html.
Full textAbstract:
Higher order modes (HOM) are electromagnetic resonant fields. They can be excited by an electron beam entering an accelerating cavity, and constitute a component of the wakefield. This wakefield has the potential to dilute the beam quality and, in the worst case, result in a beam-break-up instability. It is therefore important to ensure that these fields are well suppressed by extracting energy through special couplers. In addition, the effect of the transverse wakefield can be reduced by aligning the beam on the cavity axis. This is due to their strength depending on the transverse offset of the excitation beam. For suitably small offsets the dominant components of the transverse wakefield are dipole modes, with a linear dependence on the transverse offset of the excitation bunch. This fact enables the transverse beam position inside the cavity to be determined by measuring the dipole modes extracted from the couplers, similar to a cavity beam position monitor (BPM), but requires no additional vacuum instrumentation.At the FLASH facility in DESY, 1.3 GHz (known as TESLA) and 3.9 GHz (third harmonic) cavities are installed. Wakefields in 3.9 GHz cavities are significantly larger than in the 1.3 GHz cavities. It is therefore important to mitigate the adverse effects of HOMs to the beam by aligning the beam on the electric axis of the cavities. This alignment requires an accurate beam position diagnostics inside the 3.9 GHz cavities. It is this aspect that is focused on in this thesis. Although the principle of beam diagnostics with HOM has been demonstrated on 1.3 GHz cavities, the realization in 3.9 GHz cavities is considerably more challenging. This is due to the dense HOM spectrum and the relatively strong coupling of most HOMs amongst the four cavities in the third harmonic cryo-module. A comprehensive series of simulations and HOM spectra measurements have been performed in order to study the modal band structure of the 3.9 GHz cavities. The dependencies of various dipole modes on the offset of the excitation beam were subsequently studied using a spectrum analyzer. Various data analysis methods were used: modal identification, direct linear regression, singular value decomposition and k-means clustering. These studies lead to three modal options promising for beam position diagnostics, upon which a set of test electronics has been built. The experiments with these electronics suggest a resolution of 50 micron accuracy in predicting local beam position in the cavity and a global resolution of 20 micron over the complete module. This constitutes the first demonstration of HOM-based beam diagnostics in a third harmonic 3.9 GHz superconducting cavity module. These studies have finalized the design of the online HOM-BPM for 3.9 GHz cavities at FLASH.
19
Hu, Yikun. "A generic approach for the study of higher-order mode propagation in circular ducts with simple aperture devices." Thesis, Loughborough University, 2007. https://dspace.lboro.ac.uk/2134/19783.
Full textAbstract:
The aim of the work reported in this thesis is to establish a generic approach for the study of the propagation of higher-order modes in ducts of circular cross section when a simple aperture device is installed in the duct. Additionally to describe the effects of the simple aperture device on the whole in duct acoustic field, especially in the frequency range after the first higher-order mode cuts on. The approach, which is based on approximating each higher-order mode as an uncoupled mode, requires an accurate and effective decomposition of the in duct field in the higher frequency range. In the theoretical work for the propagation of the higher-order modes in circular ducts, one established model to describe the open end of the duct is considered. Another model to describe the sound source (both plane wave source and point source) and the boundaries between the aperture device and the main duct is proposed. Combining the two models together, a revised model to describe the whole acoustic system is obtained and used to carry out the in duct field decomposition in the higher frequency range. From this the amplitudes of various higher-order modes are obtained. Experimental investigations have also been carried out to determine the applicability of this model. The experimental work can be divided into two groups: reference measurements for the inputs to the models and direct measurements of the sound fields. The reference measurements are used to obtain the strength of the sound source. The direct measurements are used to compare with the results obtained from the theoretical calculations. Through the comparison, the errors and the applicability of the theoretical model are established. It is shown that this approach to the problem may be used in the normalized wave number region up to k * R -< 7 , which is nearly four times the plane wave region and includes sixteen propagating higher-order modes. By determining the amplitudes of the higher-order modes, the whole in-duct acoustic field is fully decomposed into individual model contributions and can be reconstructed in detail. In order to get a complete and coordinate-independent description of the effects of installing different simple aperture devices, the power radiated out of the open end of - i - the duct is calculated in the fonn of different single modes. Additionally the insertion losses for different aperture device situations are also obtained. Then through the comparison of the powers and the insertion losses, it is possible to find an effective and direct way to express the effects of installing different simple aperture devices in a duct.
20
Tam, Kwok-Leung Yves. "Pricing risk for nonnormal processes and conditional higher-order moments /." free to MU campus, to others for purchase, 1997. http://wwwlib.umi.com/cr/mo/fullcit?p9842570.
Full text
21
Rangaswami, Roopa. "A cost analysis for a higher-order parallel programming model." Thesis, University of Edinburgh, 1996. http://hdl.handle.net/1842/747.
Full textAbstract:
Programming parallel computers remains a difficult task. An ideal programming environment should enablethe user to concentrate on the problem solving activity at a convenient level of abstraction, while managing the intricate low-level details without sacrificing performance. This thesis investigates a model of parallel programming based on the Bird-Meertens Formalism (BMF). This is a set of higher-order functions, many of which are implicitly parallel. Programs are expressed in terms of functions borrowed from BMF. A parallel implementation is defined for each of these functions for a particular topology, and the associated execution costs are derived. The topologies which have been considered include the hypercube, 2-D torus, tree and the linear array. An analyser estimates the costs associated with different implementations of a given program and selects a cost-effective one for a given topology. All the analysis is performed at compile-time which has the advantage of reducing run-time overheads. the cost model's accuracy in choosing a cost-effective implementation and predicting its performance has been studied for three programs. The main contribution of the thesis is the cost model which aims to predict realistic performances and which considers several possible parallel implementations for a given programbefore selecting a cost-effective one.
22
Qin, Lihai. "Development of Reduced-Order Models for Lift and Drag on Oscillating Cylinders with Higher-Order Spectral Moments." Diss., Virginia Tech, 2004. http://hdl.handle.net/10919/29542.
Full textAbstract:
An optimal solution of vortex-induced vibrations of structures would be a time-domain numerical simulation that simultaneously solves the fluid flow and structural response. Yet, the requirements in terms of computing power remains a major obstacle for implementing such a simulation. On the other hand, lower- or reduced-order models provide an alternative for determining structural response to forcing by fluid flow. The objective of this thesis is to provide a consistent approach for the development of reduced-order models for the lift and drag on oscillating cylinders and the identification of their parameters. Amplitudes and phases of higher-order spectral moments of the lift and drag coefficients data are combined with approximate solutions of the representative models to determine their parameters. The results show that the amplitude and phase of the trispectrum could be used to model the lift on the oscillating cylinder under different excitation conditions. Moreover, the amplitude and phase of the cross-bispectrum could be used to establish the lift-drag relation for oscillating cylinders. A forced van der Pol equation is used to represent the lift on a transversely oscillating cylinder, and a parametrically excited van der Pol equation is used to model the lift coefficient on an inline oscillating cylinder. All cases of excitations lead to close values for the damping and nonlinear parameters in the van der Pol equation. Consequently, and as shown in this thesis, different excitation cases could be used to identify the parameters in the governing equations. Moreover, the results show that the drag coefficient could be derived from the lift coefficient through a square relation that takes into account the effects of the forced motions.Ph. D.
23
Yan, Xinming. "Development of robust control based on sliding mode for nonlinear uncertain systems." Thesis, Ecole centrale de Nantes, 2016. http://www.theses.fr/2016ECDN0012.
Full textAbstract:
Le travail de thèse présenté dans ce mémoire s’inscrit dans le cadre du développement de lois de commande pour des systèmes non linéaires incertains, basées sur la théorie des modes glissants. Les méthodes classiques de la commande par modes glissants sont des lois de commande par retour d’état, où la variable de glissement et ses dérivées sont nécessaires. Le premier objectif de cette thèse est de proposer des lois de commande par modes glissants d’ordre supérieur avec une réduction de l’ordre de dérivation de la variable de glissement. Le deuxième objectif est de combiner les nouvelles lois de commande avec un mécanisme de gain adaptatif. L’utilisation d’un gain adaptatif permet de simplifier le réglage du gain, de réduire le temps de convergence et d’améliorer la précision. Enfin, l’applicabilité de ces approches est démontrée à travers leur application au banc d’essais électropneumatique de l’IRCCyN, et à un système volant à trois degrés de libertéThis work deals with the development of control laws for nonlinear uncertain systems based onsliding mode theory. The standard sliding mode control approaches are state feedback ones, in which the sliding variable and its time derivatives are required. This first objective of this thesis is to propose high order sliding mode control laws with a reduced use of sliding variable time derivatives. The contributions are made for the second and third order sliding mode control. The second objective is to combine the proposed control laws with a gain adaptation mechanism. The use of adaptive gain law allows to simplify the tuning process, to reduce the convergence time and to improve the accuracy. Finally, the applicability of the proposed approaches is shown on IRCCyN pneumatic benchmark. Applications are also made on 3DOF flying system
24
Happe, Lucia [Verfasser]. "Configurable Software Performance Completions through Higher-Order Model Transformations / Lucia Happe." Karlsruhe : KIT Scientific Publishing, 2014. http://www.ksp.kit.edu.
Full text
25
Gyftodimos, Elias. "A probabilistic graphical model framework for higher-order term-based representations." Thesis, University of Bristol, 2005. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.425088.
Full text
26
Quarterman, Martyn. "Acquisition of higher-order professional competencies: a new synergistic learning model." Thesis, Anglia Ruskin University, 2017. https://arro.anglia.ac.uk/id/eprint/701818/1/Quarterman_2017.pdf.
Full textAbstract:
Context:
This research centres on the acquisition of professional competencies by graduates
who have recently entered the construction industry. Many professional
competencies involve critical thinking and subjective decision-making under
conditions of uncertainty and variability; and therefore require higher-order abilities
to accomplish. The acquisition of these competencies has been shown to be
problematic, difficult to achieve and to take longer than anticipated. The aim of this
research was to determine if acquisition could be enhanced and/or accelerated.
Research Design:
The research design adopted a mixed methods approach. The study commenced
by identifying and defining the problematic competencies through a process of
qualitative research. This was followed by analysis of existing learning theories and
non-traditional learning techniques that had been applied in other contexts through a
search of the literature and published accounts of applications. The analysis
identified constituent parts of theories and practice which were developed into an
innovative learning model. The model was tested through a process of quantitative
research conducted using a controlled experiment with a sample of new-entrant
graduates employed by professional firms.
Findings:
The research produced a new model of learning comprising a unique combination of
learning theories, practices and applicational constituents which acted in a
synergistic way to enhance the acquisition of higher-order professional
competencies. The research identified synergy as an important factor in the design
and efficacy of the model, hitherto not recognised.
Conclusions:
The research has shown that higher-order professional competencies can be
acquired faster and more effectively. It has developed and extended the learning
theory of Bancroft, Burguillo, Lui et al and others through the identification of
synergy as a significant factor. The research concludes by demonstrating that the
learning model can reasonably be transferred to other new-entrants within the built
environment industry and generalised to the development of graduate new-entrants
in other professional sectors.
27
Quarterman, Martyn. "Acquisition of higher-order professional competencies : a new synergistic learning model." Thesis, Anglia Ruskin University, 2017. http://arro.anglia.ac.uk/701818/.
Full textAbstract:
Context This research centres on the acquisition of professional competencies by graduates who have recently entered the construction industry. Many professional competencies involve critical thinking and subjective decision-making under conditions of uncertainty and variability; and therefore require higher-order abilities to accomplish. The acquisition of these competencies has been shown to be problematic, difficult to achieve and to take longer than anticipated. The aim of this research was to determine if acquisition could be enhanced and/or accelerated. Research Design The research design adopted a mixed methods approach. The study commenced by identifying and defining the problematic competencies through a process of qualitative research. This was followed by analysis of existing learning theories and non-traditional learning techniques that had been applied in other contexts through a search of the literature and published accounts of applications. The analysis identified constituent parts of theories and practice which were developed into an innovative learning model. The model was tested through a process of quantitative research conducted using a controlled experiment with a sample of new-entrant graduates employed by professional firms. Findings The research produced a new model of learning comprising a unique combination of learning theories, practices and applicational constituents which acted in a synergistic way to enhance the acquisition of higher-order professional competencies. The research identified synergy as an important factor in the design and efficacy of the model, hitherto not recognised. Conclusions The research has shown that higher-order professional competencies can be acquired faster and more effectively. It has developed and extended the learning theory of Bancroft, Burguillo, Lui et al and others through the identification of synergy as a significant factor. The research concludes by demonstrating that the learning model can reasonably be transferred to other new-entrants within the built environment industry and generalised to the development of graduate new-entrants in other professional sectors.
28
Niblett, Samuel Peter. "Higher order structure in the energy landscapes of model glass formers." Thesis, University of Cambridge, 2018. https://www.repository.cam.ac.uk/handle/1810/277582.
Full textAbstract:
The study of supercooled liquids and glasses remains one of the most divisive and divided fields in modern physics. Despite a vast amount of effort and research time invested in this topic, the answers to many central questions remain disputed and incomplete. However, the link between the behaviour of supercooled liquids and their energy landscapes is well established and widely accepted. Understanding this link would be a key step towards resolving many of the mysteries and controversies surrounding the glass transition. Therefore the study of glassy energy landscapes is an important area of research. In this thesis, I report some of the most detailed computational studies of glassy potential energy landscapes ever performed. Using geometry optimisation techniques, I have sampled the local minima and saddle points of the landscapes for several supercooled liquids to analyse their dynamics and thermodynamics. Some of my analysis follows previous work on the binary Lennard-Jones fluid (BLJ), a model atomic liquid. BLJ is a fragile glass former, meaning that its transport coefficients have super-Arrhenius temperature dependence, rather than the more usual Arrhenius behaviour exhibited by strong liquids. The difference in behaviour between these two classes of liquid has previously been attributed to differing degrees of structure in the relevant energy landscapes. I have studied models for both fragile and strong glass formers: the molecular liquid ortho-terphenyl (OTP) and viscous silica (SiO$_{2}$) respectively. My results for OTP agree closely with trends observed for BLJ, suggesting that the same diffusion mechanism is applicable to fragile molecular liquids as well as to atomic. However, the dynamics and energy landscape of OTP are made complicated by the molecular orientational degrees of freedom, making the analysis more challenging for this system. Dynamics of BLJ, OTP and silica are all dominated by cage-breaking events: structural rearrangements in which atoms change their nearest neighbours. I propose a robust and general method to identify cage breaks for small rigid molecules, and compare some properties of cage breaks between strong and fragile systems. The energy landscapes of BLJ and OTP both display hierarchical ordering of potential energy minima into metabasins. These metabasins can be detected by the cage-breaking method. It has previously been suggested that metabasins are responsible for super-Arrhenius behaviour, and are absent from the landscapes of strong liquids such as SiO2. My results indicate that metabasins are present on the silica landscape, but that they each contain fewer minima than metabasins in BLJ or OTP. Metabasins are associated with anticorrelated particle motion, mediated by reversed transitions between minima of the potential energy landscape. I show that accounting for time-correlation of particle displacement vectors is essential to describe super-Arrhenius behaviour in BLJ and OTP, but also required to reproduce strong behaviour in silica. I hypothesise that the difference between strong and fragile liquids arises from a longer correlation timescale in the latter case, and I suggest a number of ways in which this proposition could be tested. I have investigated the effect on the landscape of freezing the positions of some particles in a BLJ fluid. This “pinning” procedure induces a dynamical crossover that has been described as an equilibrium “pinning transition”, related to the hypothetical ideal glass transition. I show that the pinning transition is related to (and probably caused by) a dramatic change in the potential energy landscape. Pinning a large fraction of the particles in a supercooled liquid causes its energy landscape to acquire global structure and hence structure-seeking behaviour, very different from the landscape of a typical supercooled liquid. I provide a detailed description of this change in structure, and investigate the mechanism underlying it. I introduce a new algorithm for identifying hierarchical organisation of a landsape, which uses concepts related to the pinning transition but is applicable to unpinned liquids as well. This definition is complementary to metabasins, but the two methods often identify the same higher-order structures. The new “packings” algorithm offers a route to test thermodynamic theories of the glass transition in the context of the potential energy landscape. Over the course of this thesis, I discuss several different terms and methods to identify higher-order structures in the landscapes of model glass formers, and investigate how this organisation varies between different systems. Although little variation is immediately apparent between most glassy landscapes, deeper analysis reveals a surprising diversity, which has important implications for dynamical behaviour in the vicinity of the glass transition.
29
Brand, Michael Max. "HOOD : a Higher-Order Object-Oriented Database model and its implementation." Master's thesis, University of Cape Town, 1992. http://hdl.handle.net/11427/17375.
Full textAbstract:
Bibliography: pages 133-140.There is no accepted standard for the object-oriented database paradigm at present, which has led to different definitions of features and conformance requirements. HOOD is a Higher-Order Object-Oriented Database system which defines a meta-data model for specifying the requirements of an Object-Oriented Database, which provides uniformity and extensibility. From this specification and by making use of a comprehensive structure system, an exemplar or implementation model is defined. Among the constructs provided by the model are types, instances, objects, values, methods, base types, generic types and metatypes. The mechanisms of instantiation and subtyping allow for relationships between these constructs. Extensibility is provided in the model for types, base types, structures and methods. Uniformity is achieved by defining all constructs as instances and through the use of messages for all operations. There is only one form of object construct which provides persistence and identities. The complex values and extensibility of the model allow it to adapt in order to model the real world instead of adapting the real world to fit the model. We have implemented a subset of the structures and values defined in the model, provided persistence and identities for object, and included the various constructs mentioned above. The method language allows for the specification of methods, the passing of messages, and the use of complex values. The compiler performs type checking and resolution and generates instructions for an abstract machine which manipulates the database.
30
Anderson, Gemma Jayne. "Inflationary model constraints using higher-order statistics of the primordial curvature perturbation." Thesis, University of Sussex, 2014. http://sro.sussex.ac.uk/id/eprint/50744/.
Full textAbstract:
Cosmological inflation is the leading candidate for the origin of structure in the Universe. However, a huge number of inflationary models currently exist. Higher-order statistics, particularly the bispectrum and trispectrum, of the primordial curvature perturbation can potentially be used to discriminate between competing models. This can provide an insight into the precise physical mechanism of inflation. Current constraints on inflationary models using the amplitude fNL of the bispectrum are quoted for specific templates. This results in much of the inflationary parameter space remaining unexplored. By utilizing the symmetries of the underlying quasi-de Sitter spacetime to construct a generic ‘effective field theory' Lagrangian with adjustable parameters, one can encompass many single-field models of inflation in a unifying framework. In the first part of this thesis we perform a partial-wave decomposition of the bispectrum produced at horizon-exit by each operator in the effective Lagrangian, which we use to find the principal components using a Fisher-matrix approach. This allows us to probe much more of the parameter space. Cosmic Microwave Background bispectrum data is used to estimate the amplitude of each component, which can then translated into constraints on particular classes of single-field models. We consider the implications for DBI and ghost inflation as examples. In the second part of this thesis we extend the transport formalism, first introduced by Mulryne, Seery and Wesley, to calculate the trispectrum generated during superhorizon evolution in inflationary models with multiple fields. We provide transport equations that track the evolution of the local trispectrum non-linearity parameters tNL and gNL throughout inflation. We compute these for several models as examples.
31
Zhang, Lei. "Contribution to robust and adaptive control and observation of linear induction machine : High order sliding mode approach." Thesis, Bourgogne Franche-Comté, 2018. http://www.theses.fr/2018UBFCA010.
Full textAbstract:
Les effets d’extrémité jouent un rôle important dans la modélisation et la commande de la Machine Linéaire à Induction (MLI). Ces phénomènes augmentent significativement la non-linéarité du modèle de la machine et génèrent plusieurs difficultés pour contrôler et observer ses états avec de bonnes performances. Cette thèse aborde trois problématiques distinctes : la commande robuste de la MLI, l’estimation de la vitesse et du flux de la MLI et le contrôle robuste à base d’observateur en utilisant la théorie du mode glissant d’ordre supérieur.Dans la première partie de la thèse, trois contrôleurs robustes assurant la poursuite de trajectoire de la vitesse et du flux pour la MIL ont été développés : le Super Twisting (ST), le Super Twisting Adaptatif (STA) et le Twisting Adaptatif (TA). Ces commandes ont été testées en simulations et leurs performances ont été démontrées. Ainsi, le ST assure un contrôle continu avec convergence à temps fini de l’erreur à zéro malgré les perturbations, sous l’hypothèse que les bornes des incertitudes sont connues. Cette hypothèse est relaxée dans le cas du TA et du STA grâce à leurs propriétés adaptatives.Dans la deuxième partie de la thèse, un nouveau modèle du MLI a été proposé et son observabilité a été démontrée. Ensuite un Observateur par Mode Glissant d’Ordre Deux (MGOD) et un Observateur par Mode Glissant d’Ordre Supérieur (MGOS) ont été synthétisé afin d’estimer la vitesse et le flux du MLI, uniquement en utilisant la mesure des tensions et des courants statorique. La stabilité des deux observateurs a été prouvée par une approche de Lyapunov et leurs performances ont été démontrées à travers des simulations.Dans la dernière partie de la thèse, deux commandes par rejet actif des perturbations sont synthétisées. Ainsi et dans un premier temps, le modèle de la MLI est décomposé en deux sous-systèmes du second ordre. Ensuite, deux contrôleurs (le twisting et le super-twsiting) ont été synthétisés afin d’assurer la poursuite du flux et de la vitesse. Le MGOS est utilisé pour estimer les dérivées du flux et de la vitesse, ainsi que pour l’estimation en temps réel de la perturbation. Les contrôleurs quant à eux assurent la compensation des perturbations et la poursuite des trajectoires du flux et de la vitesse. La stabilité et la convergence des deux commandes proposées ont été prouvées et leurs performances démontrées par simulationDynamic end effects play an important role in the Linear Induction Machine (LIM) control. They increase significantly the nonlinearity of the machine model and generate several difficulties to control and observe states with good performances. This thesis addresses three distinctissues: LIM robust control, LIM speed and flux estimation and observer-based robust control using higher order sliding mode theory.In the first part, to achieve speed and flux tracking,Super Twisting Controller (STC), Adaptive Super Twisting Controller (ASTC), and Adaptive Twisting Controller (ATC) were proposed and implemented into LIM system with great performance, i.e. finite time convergence and robustness properties. Among them, STC ensures continuous control with finite time convergence of the error to zero despite disturbances, under the assumption that their bounds are known. ATC and ASTC can deal with unknown bounded disturbance thanks to their adaptive properties.In the second part, a novel simplified LIM model was proposed and its observability has been proved. Then, Second Order Sliding Mode Observer (SOSMO) and Adaptive High Order Sliding Mode Observer (HOSMO) were proposed to estimate LIM speed, only by using the measured stator voltages and stator currents. SOSMO observer is based on the super twisting algorithm and its stability has been proved with Lyapunov’s theory, which can guarantee finite time convergence with less chattering. Adaptive HOSMO strategy combines speed adaptive algorithm and HOSMO method together to estimate rotor fluxes and speed simultaneously.In the third part, the LIM is viewed as two second order subsystems. Moreover, only the speed and the flux are supposed to be measured. Based on that two differentcontrollers based on HOSMO were presented in order to achieve flux and speed tracking. In both controllers, the idea of active disturbance rejection control is applied. Hence, the HOSMO is used to estimate the derivatives of the flux and the speed, as well as the disturbance. Then, in order to deal with the uncertainty in the measured variables, two different SM controllers are proposed. Firstly, the TC is applied in the LIM. However, the control signal in this case is discontinuous. Then, in order to provide a continuous control signal, the TC is replaced with STC. The stability and convergence of proposed TC-HOSMO and STC-HOSMO approaches were given and simulation validated their performances
32
Kim, Jeonghoon. "Investigation of the Herschel-Quincke tube concept in a rectangular lined duct." Thesis, Virginia Tech, 2001. http://hdl.handle.net/10919/46175.
Full textAbstract:
In this research an innovative combination of the Herschel-Quincke tubes and traditional liners is proposed for application in noise reduction of aircraft engines. The approach consists of installing Herschel-Quincke (HQ) tubes on lined rectangular ducts. An analytical model was developed to predict the effects of HQ tubes applied to rectangular lined ducts. The technique involves assuming the tube-duct interfaces as finite piston sources. These sources couple the acoustic field inside the duct with the acoustic field within the HQ tubes. The accuracy of the analytical model was validated with experimental data. Three different types of experimental configurations were tested: liner only, HQ tube with a hard wall duct, and HQ tubes with liners. Analytical predictions were shown to correlate well with the experimental data. Two typical types of liners, perforate and linear, were tested in these investigations. The perforate and linear liners with HQ systems showed better sound attenuations than the HQ tubes with hard walled ducts and liners only systems. The performance of the perforate and linear liners with HQ tubes were investigated in various configurations. The results indicated possible combinations which show great potential for reducing the noise within the ducts.Master of Science
33
Garbin, Turpaud Fernando, and Pachas Ángel Alfredo Lévano. "Higher-order non-local finite element bending analysis of functionally graded." Bachelor's thesis, Universidad Peruana de Ciencias Aplicadas (UPC), 2019. http://hdl.handle.net/10757/626024.
Full textAbstract:
La teoría de vigas de Timoshenko TBT y una teoría de alto orden IFSDT son formuladas utilizando las ecuaciones constitutivas no locales de Eringen. Se utilizaron ecuaciones constitutivas en 3D en el modelo IFSDT. Se utilizó una variación del material con el uso de materiales funcionalmente graduados a lo largo del peralte de una viga de sección rectangular. El principio de trabajos virtuales utilizado y ejemplos numéricos fueron presentados para comparar ambas teorías de vigas.Timoshenko Beam Theory (TBT) and an Improved First Shear Deformation Theory (IFSDT) are reformulated using Eringen’s non-local constitutive equations. The use of 3D constitutive equation is presented in IFSDT. A material variation is made by the introduction of FGM power law in the elasticity modulus through the height of a rectangular section beam. The virtual work statement and numerical results are presented in order to compare both beam theories.
Tesis
34
Fishbaugh, James. "Development of a Higher-Order Ice Sheet Model Using a Rescaled Coordinate System." The University of Montana, 2008. http://etd.lib.umt.edu/theses/available/etd-05302008-101724/.
Full textAbstract:
The Intergovernmental Panel on Climate Change (IPCC) has estimated between 9 and 88 cm of sea level rise over the next hundred years. Of this, only negative 19 to 11 cm is attributed to the largest ice masses on the planet, the Antarctic and Greenland ice sheets. Over the last decade, dramatic activity in the outlet glaciers of Greenland and the Antarctic Peninsula raise the possibility that these large ice sheets will have a much greater contribution to sea level rise over the next century than was predicted by the IPCC. Recent studies have shown these areas are exhibiting decadal scale changes in response to climate forcings, whereas IPCC models show that ice is not responsive to climate change over such short periods of time. Many believe the IPCC type models fail to show short term climate responses due to the simplifications they make to ice sheet mechanics. Here, we develop a higher-order model -- a new ice sheet model which contains all relevant flow physics. In order to gauge our progress, we perform a verification of our model around a structured set of experiments. The analysis reveals our model is performing well over a range of different scenarios.
35
陸貴文 and Kwai-man Luk. "Complex-source-point theory of the higher-order modes in an open resonator." Thesis, The University of Hong Kong (Pokfulam, Hong Kong), 1985. http://hub.hku.hk/bib/B31230532.
Full text
36
Luk, Kwai-man. "Complex-source-point theory of the higher-order modes in an open resonator /." [Hong Kong] : University of Hong Kong, 1985. http://sunzi.lib.hku.hk/hkuto/record.jsp?B12315382.
Full text
37
Shaner, Steve M. "Modular verification of higher-order methods with mandatory calls specified by model programs." [Ames, Iowa : Iowa State University], 2008.
Find full text
38
Weathersby, Stephen. "Damping higher order modes in the PEP-II B-factory storage ring collider." Diss., Connect to online resource - MSU authorized users, 2007.
Find full textAbstract:
Thesis (Ph.D.)--Michigan State University. Dept. of Physics and Astronomy, 2007.Title from PDF t.p. (viewed on August 18, 2009) Includes bibliographic references (p. 175-179). Also issued in print.
39
Poutous, Menalaos. "Stable continuous-wave operation of Ti:Sapphire lasers in higher-order transverse Hermite-Gaussian modes." Diss., Georgia Institute of Technology, 1996. http://hdl.handle.net/1853/29877.
Full text
40
Wang, Chaohui. "Distributed and Higher-Order Graphical Models : towards Segmentation, Tracking, Matching and 3D Model Inference." Phd thesis, Ecole Centrale Paris, 2011. http://tel.archives-ouvertes.fr/tel-00658765.
Full textAbstract:
This thesis is devoted to the development of graph-based methods that address several of the most fundamental computer vision problems, such as segmentation, tracking, shape matching and 3D model inference. The first contribution of this thesis is a unified, single-shot optimization framework for simultaneous segmentation, depth ordering and multi-object tracking from monocular video sequences using a pairwise Markov Random Field (MRF). This is achieved through a novel 2.5D layered model where object-level and pixel-level representations are seamlessly combined through local constraints. Towards introducing high-level knowledge, such as shape priors, we then studied the problem of non-rigid 3D surface matching. The second contribution of this thesis consists of a higher-order graph matching formulation that encodes various measurements of geometric/appearance similarities and intrinsic deformation errors. As the third contribution of this thesis, higher-order interactions were further considered to build pose-invariant statistical shape priors and were exploited for the development of a novel approach for knowledge-based 3D segmentation in medical imaging which is invariant to the global pose and the initialization of the shape model. The last contribution of this thesis aimed to partially address the influence of camera pose in visual perception. To this end, we introduced a unified paradigm for 3D landmark model inference from monocular 2D images to simultaneously determine both the optimal 3D model and the corresponding 2D projections without explicit estimation of the camera viewpoint, which is also able to deal with misdetections/occlusions
41
Aydin, Emine Dilara. "A higher-order transport model for photon propagation and its applications to optical tomography." Thesis, Imperial College London, 1999. http://hdl.handle.net/10044/1/8236.
Full text
42
Barth, Alexander [Verfasser], Johann [Akademischer Betreuer] Reger, Pérez Jaime Alberto [Gutachter] Moreno, and Martin [Gutachter] Horn. "Indirect adaptive higher-order sliding-mode control using the certainty-equivalence principle / Alexander Barth ; Gutachter: Jaime Alberto Moreno Pérez, Martin Horn ; Betreuer: Johann Reger." Ilmenau : TU Ilmenau, 2020. http://d-nb.info/1224416597/34.
Full text
43
Chuai, Kun. "High order phase-locked loop design and test for time-mode signal processing applications." Thesis, McGill University, 2010. http://digitool.Library.McGill.CA:80/R/?func=dbin-jump-full&object_id=95015.
Full textAbstract:
This thesis first presents a pole-zero placement algorithm for the systematic design of high-order phase-locked loops (PLL) serving as anti-imaging and anti-aliasing filters for time-mode signal processing applications. A 6th order PLL is designed and fabricated on a printed circuit board and is interfaced to a production mixed-signal tester. The correct filtering operation and large-signal transfer characteristic of the PLL are verified with an all-digital DFT solution. The digital test input is driven by a single clock, which can be programmed directly from an ATE high-speed digital pattern generator. As application of these high-order PLLs, an accurate and low-cost clock delay generation system is presented. With proper compensation and calibration, a delay resolution of 15 ps is achieved over an 8.4 ns range. This technique is shown experimentally to be a viable solution for clock alignment and for measuring jitter at a 50 GHz effective sampling rate.Ce mémoire présente tout d'abord une approche systématique descendante pour la conception de boucles à verrouillage de phase (PLL) ayant un ordre arbitraire et opérant comme filtre anti-image ou anti-repliement pour le traitement de signal dans le domaine temporel. Un PLL de 6e ordre a été conçu et fabriqué sur une carte de circuit imprimé montée sur un tester à signaux-mixtes (ATE). La fonction de filtrage et la caractéristique de transfert de grands-signaux sont vérifiées à l'aide d'une solution de conception pour test (DFT) entièrement numérique. Le signal d'entrée numérique est cadencé par une horloge unique. Par conséquent, le signal de test peut être programmé sans effort à partir de l'instrument numérique à haute-vitesse (HSD) d'un testeur à signaux-mixtes (ATE). De plus, un système précis et économique de génération de délai d'horloge est présenté comme une application du PLL construit. A l'aide de calibration et compensation appropriées, une résolution de délai de l'ordre de 15 ps est réalisée pour un intervalle de 8.4 ns. Cette technique est démontrée expérimentalement comme étant une solution viable pour l'alignement d'horloge et pour mesurer le vacillement d'horloge à un rythme de sous-échantillonnage de 50 GHz.
44
Chen, Chih-Chiang, and 陳志強. "Microstrip Line Syntheses for Quasi-TEM Mode and First Higher-Order Mode." Thesis, 2004. http://ndltd.ncl.edu.tw/handle/6v2pp8.
Full textAbstract:
博士國立交通大學
電信工程系所
92
This dissertation studies microstrip transmission line syntheses for quasi-transverse electromagnetic (Quasi-TEM, EH0) mode and the first higher-order (EH1) mode. The dissertation mainly consists of two parts, investigating a new synthetic transmission line for miniaturizing microwave passive circuits and presenting a novel synthetic beam-steering leaky-wave antenna. The first part presents a synthetic two-dimensional transmission line (2-D TL) that supports quasi-TEM propagation mode and reduces problems associated with compacted meandering of microstrip (MS) on propagation constants and the characteristic impedances commonly observed in conventional one-dimensional MSs. The proposed 2-D TL comprises two layers of metallic surfaces on either side of a dielectric substrate. The top metal surface is a meandered connection of a unit cell with a central patch and connecting arms. The bottom surface is a meshed 2-D periodical ground plane, whose etched portion complements the patch portion of the top surface, forming a complementary-conducting-strip (CCS) TL, enabling a combination of an MS and MS with the tuning septa in a unit cell. Both theoretical and experimental investigations of the CCS TL agree well and demonstrate that it is much less susceptible to the effects of meanderings on the propagation constant and characteristic impedance than an MS for the same meandered pattern, where the synthetic CCS TL can provide wider choice of characteristic impedance and flatter propagation characteristic. Two design examples are presented to demonstrate the potential for a CCS TL for miniaturizing microwave passive circuits with minimal losses. The first example involves a 5.4-GHz CCS four-port rat-race hybrid realized in RO4003 and reduces the area of original MS design by 87 %. The second example illustrates the applicability of a CCS TL to a monolithic RF integrated circuit using a first-pass design of a 5.2-GHz CMOS oscillator incorporating a CCS TL as a resonator with an area totaling 500x600 um2 including pads base on Taiwan Semiconductor Manufacturing Company's 0.25-um 1P5M CMOS process techniques. In the second part of the dissertation a novel synthetic beam-steering leaky-wave antenna that uses reactive loading capacitors along the leaky line is presented. The reactive loading varies the phase constant of the leaky line, altering direction of the main beam. A prototype was constructed and tested, demonstrating that a beam scanning angle of 23-degree is obtained by periodically loading the 0.06527-pF capacitors along the leaky line at 4 GHz. A compacted, electronic beam-steering antenna of scanning angle 13-degree was established by replacing the 79 MIM capacitors with four varactors.
45
Peschke, Claudius [Verfasser]. "Higher-Order-Mode-Dämpfer als Strahllagemonitore / von Claudius Peschke." 2008. http://d-nb.info/98734692X/34.
Full text
46
Chi-ChihChen and 陳驥之. "Mode converter for higher order mode fiber dispersion compensation using shortcut to adibaticity." Thesis, 2014. http://ndltd.ncl.edu.tw/handle/67005947681172991975.
Full textAbstract:
碩士國立成功大學
光電科學與工程學系
102
In our research, we develop a fiber dispersion compensation module based on higher-order modes. By using higher order modes, we can obtain smaller nonlinear effect, tailorable dispersion curve, therefore, this module is very compatible with the high power laser module. The key components of this module are the mode converter and a well-designed dispersion compensation fiber. By using long period grating (LPG), designing the coupling region of a resonant mode converter to the half of the beat length, we can achieve total power mode conversion. This kind of mode converter is easier to fabricate but having less error tolerance and narrow bandwidth. Recently, the analogies between quantum theory and waveguide optics has been investigated. From this, we can develop the mode converter with better error tolerance through adiabatic theory which has been used in the quantum control. For the adiabatic following mode converter, the device length must be long enough to satisfy the adiabatic condition. We can add the counter-diabatic term into the mode converter design to get the improvement but it requires an extra step in fabrication. Therefore, we introduce the rotation method of Hamiltonain to simplify the fabrication process into one step. For dispersion compensation, we propose to use the fiber with core-ring-trench structure to get the tailarable dispersion curve in the LP02 mode. We develop a finite-difference-based numerical tool to design and analyze these kinds of fibers.
47
Yang, Ge, and 楊格. "Higher-Order Mode Analysis and Shape Optimization of Plenum Systems." Thesis, 2012. http://ndltd.ncl.edu.tw/handle/87943704860238861350.
Full textAbstract:
碩士大同大學
機械工程學系(所)
100
At low frequency, the sound will propagate in mufflers only in a plane wave type, however, for a high frequency, the higher-order mode effect occurred that will result a difference between the measurement and the theory. Research on new techniques of three-dimensional wave propagating in muffler has been discussed in recent literature; however, the research work of a multi-chamber and a chamber hybridized with plates which may efficiently increase the acoustical performance is rare. Therefore, the main goal of this paper is not only to analyze the sound propagating of simple mufflers and mufflers system but also to optimize their best design shape within a limited space. In this paper, the chamber is modeled as a piston-driven rectangular tube. Using the eigenfunction technique to obtained a four-pole matrix and then calculate the sound transmission loss for a three-dimension wave propagating in chambers. The geometric parameters of chamber such as the length, the width, the height, and the location of inlet/outlet can be putted anywhere. Subsequently, analyzing the STL for various mufflers and comparing the theoretical data with the literature yield that the mathematical model of the mufflers is correct. In order to maximize the acoustical performance, the shape optimization of mufflers in connection with the genetic algorithm is performed. The result indicated that the STL at the target frequency will be improved. Furthermore, the broadband STL will increase when the chambers increase in the muffler.
48
PAN, QUAN-WEN, and 潘權文. "Development of Higher-order Circumferential Mode Disc-typed Ultrasonic Motors." Thesis, 2008. http://ndltd.ncl.edu.tw/handle/27237441559414716523.
Full textAbstract:
碩士國立交通大學
機械工程系所
96
This thesis proposes a disc-typed ultrasonic motor (USM) driven by a higher order circumferential ridge waves around its inner stiffened circular ring. The motor stator is made of an aluminum alloy disk supported at its outer edge and a PZT-4 annular disk with segmented dual phase electrodes. A directional traveling wave is formed from constructive interference of two equal-intensity standing waves induced by those transducers using dual sinusoidal excitations in 90 degree phase difference. The circumferential mode (1, 3) is selected to drive the USM since it has the widest modal separation from its adjacent resonant frequencies and provides three contact points to get rid of wobble motion happened to the rotor. The maximum amplitude of circumferential displacement is proportional to the revolution speed. The motor stator is required to have enough torsional rigidity to support output torque. A good design of USM has an optimal compromise between revolution speed and output torque. The inner radius and height of the stiffened circular ring are considered as two design parameters for optimal design. The prototypes having inner radius of 18 mm and the heights of inner rings of 4, 5, 6 mm were developed in this study. The fabrication includes opposite direction poling in thickness of PZT-4 annular disks. The resonant frequency of mode (1, 3) measured by impedance analyzer and laser Doppler vibrometer is around 37 kHz, which is used to be the operating frequency for the USM. The revolution speed decreases with the increase of pre-stress exerted by the rotor against the stator.
49
Lo, Yi-Chun, and 羅一鈞. "Design of the Slotline First-higher-order Leaky-mode Antennas." Thesis, 1999. http://ndltd.ncl.edu.tw/handle/35836212127531374228.
Full textAbstract:
碩士國立交通大學
電信工程系
87
This thesis presents two types of feedline structure to excite the first slotline's higher order leaky mode. First type is parallel-strips fed, second type is microstrip line fed and to compare with microstrip line coupled fed. We use a fed method that can obtain wide bandwidth. We establish a modal to calculate antenna radiation patterns. Finally, the measurement results are shown to be in good agreement with the numerical results.
50
Sung, Chieh, and 宋傑. "SIMULATION STUDY OF HIGHER-ORDER-MODE DAMPING OF STORAGE RING CAVITIES." Thesis, 2001. http://ndltd.ncl.edu.tw/handle/64478990933166750209.
Full textAbstract:
碩士國立清華大學
物理學系
89
We present studies of a higher-order-mode coupling device, which employs a circular waveguide to coaxial transition (CWCT). The waveguide is double-ridged. A properly shaped back cavity at the far end allows broadband coupling to a coaxial window. Configurations of CWCTs with either symmetric or asymmetric ridge depth are optimized with the HFSS code. HFSS calculations have also been performed to examine CWCT damping effects on a DORIS box cavity. The anti-symmetric modes are shown to be much more effectively damped by the asymmetric CWCT, however, relative merits of symmetric and asymmetric CWCTs depend on other factors such as the cavity configuration. We also make optimizations of CWCT structure and discuss the fundamental mode damping effect of our newly designed symmetric coupler. A simulation study of the vacuum window for 7/8” coaxial is also included as an appendix.