Tesis: "Dynamic gain"

1

Jones, Christopher D. C. "Dynamic gain-scheduled control of a nonlinear UCAV model". Thesis, University of Bristol, 2005. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.424426.

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2

THOMAS, DJEISSON HOFFMANN. "CONTROL SYSTEM TO SUPPRESS GAIN DYNAMIC INSTABILITIES OF AN EDFA". PONTIFÍCIA UNIVERSIDADE CATÓLICA DO RIO DE JANEIRO, 2003. http://www.maxwell.vrac.puc-rio.br/Busca_etds.php?strSecao=resultado&nrSeq=3954@1.

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CONSELHO NACIONAL DE DESENVOLVIMENTO CIENTÍFICO E TECNOLÓGICO
ERICSSON DO BRASIL
Objetivando suprimir as instabilidades dinâmicas de ganho em um amplificador à fibra dopada com Érbio (EDFA), uma nova configuração de laser em anel é apresentada e demonstrada. Neste trabalho, analizamos os efeitos da variação do nível de atenuação no laço de re-alimentação sobre a resposta transitória do EDFA. Particularmente, observamos as excursões de ganho experimentadas pelo canal sobrevivente quando sete dentre oito canais da rede são adicionados ou removidos, à exemplo do que ocorre em sistemas WDM reais. Sob esta análise, avaliamos o desempenho do sistema em suprimir as instabilidades dinâmicas de ganho do EDFA.
A new ring laser configuration to eliminate the gain dynamic instabilities of an erbium doped fiber amplifier (EDFA) is proposed and demonstrated. We examine the effect of the attenuation level in the optical feedback path over thetransient response of the EDFA. In particular, we look at the transient gain excursions experienced by surviving channel when seven of eight channels are added or dropped, like in real WDM systems. Using this analysis as a guide, we highlight the robustness of the approach and evaluate its performance to EDFA gain stabilization.

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3

Szabo, Melinda Dora. "Adaptive gain spatial receiver for wide dynamic range communication links". Thesis, Massachusetts Institute of Technology, 2020. https://hdl.handle.net/1721.1/130198.

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Thesis: M. Eng., Massachusetts Institute of Technology, Department of Electrical Engineering and Computer Science, May, 2020
Cataloged from student-submitted PDF of thesis.
Includes bibliographical references (pages 317-323).
Wireless optical communication facilitates high-speed transmission across long distances. However, time-varying and spatially-dependent attenuation through freespace channels due to scattering impedes operation for many wide dynamic range links. In the atmosphere, communication is often limited to short transmission times when optimal power is delivered to the detector, as the distance and channel conditions between ground terminals and airborne or space systems changes constantly. This effect is even more apparent in oceans, where optical attenuation varies so drastically that it has hindered practical implementation of high-speed communication undersea. To accommodate the wide range of input powers, a novel adaptive gain spatial receiver is developed in this thesis. The designed device replaces multiple detector functions of an existing underwater laser communication system with an adjustable gain and sensitivity receiver for long-range or high-rate transmissions. The novel receiver also provides spatial resolution for improved efficiency and performance. In preliminary laboratory tests, a proof-of-concept setup validates simulation expectations and informs future terminal integration. Using the new system, a wide range of input power across six orders of magnitude down to single photon detection and data rates up to 1Gb/s are attainable, which will enable future tests in the open ocean.
by Melinda Dora Szabo.
M. Eng.
M.Eng. Massachusetts Institute of Technology, Department of Electrical Engineering and Computer Science

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4

Kadhim, Ali. "Estimation of the Dynamic Relative Gain Array for Control Configuration Selection". Licentiate thesis, Luleå tekniska universitet, Signaler och system, 2015. http://urn.kb.se/resolve?urn=urn:nbn:se:ltu:diva-26177.

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The control of multi-input multi-output systems (MIMO) is more difficult than for single-input single-output systems (SISO) due to the multitude of input-output couplings. Coupling, simply means that a change in any input leads to changes in many outputs. Nevertheless, in many cases, a simple decentralised controller is usually sufficient to achieve desired performance goals. However, there is a need for systematic techniques that can suggest the most promising configurations or pairings for the decentralized controller.The relative gain array (RGA) has proven itself to be an efficient tool to solve the pairing problem. It is easily calculated and does not depend on input-output scaling. However, it gives misleading results in some cases where system dynamics are involved and hence Dynamic Relative Gain Array (DRGA) used instead. The commonplace procedure to estimate DRGA values from the input-output data is to identify a parametric system model. Thus, the user needs to decide a model structure and a model order to calculate the system frequency response. Eventually, DRGA values are obtained based on that system frequency response over the frequency range of interest. In this work, a method which requires less user interaction is proposed. The system frequency response, and subsequently the DRGA, is directly estimated from the input-output data by employing a non-parametric identification approach. Such an approach reduces the uncertainties arising from incorrect user decisions by avoiding the parametric model identification. However, DRGA values obtained by the nonparametric identification are subject to different uncertainty sources such as system nonlinearity and noise. In this thesis various strategies are presented to reduce the effect of these uncertainties. In that direction, RGA (DRGA) of linear systems is first analysed using a random excitation signal. Due to the nonperiodic nature of the random signal, the frequency response is susceptible to leakage. To reduce the leakage effect, data is divided into sub-records and the frequency response was averaged over these sub-records. Although the data division proved to be efficient in limiting the leakage effect it has a drawback of reducing the frequency resolution. Moreover, RGA (DRGA) of weakly nonlinear systems is analysed using a multisine excitation signal. The multisine excitation is used to distinguish between the nonlinear distortion and the output noise. It is very difficult to make such distinction using the random excitation. However, long experimental time is needed in returns. To overcome the shortcomings represented by low frequency resolution and the experiment running time, local polynomial approximation approach (LPA) is investigated using both random and multisine excitation.In that direction, RGA (DRGA) of linear systems is first analysed using a random excitation signal. Due to the nonperiodic nature of the random signal, the frequency response is susceptible to leakage. To reduce the leakage effect, data is divided into sub-records and the frequency response was averaged over these sub-records. Although the data division proved to be efficient in limiting the leakage effect it has a drawback of reducing the frequency resolution. Moreover, RGA (DRGA) of weakly nonlinear systems is analysed using a multisine excitation signal. The multisine excitation is used to distinguish between the nonlinear distortion and the output noise. It is very difficult to make such distinction using the random excitation. However, long experimental time is needed in returns. To overcome the shortcomings represented by low frequency resolution and the experiment running time, local polynomial approximation approach (LPA) is investigated using both random and multisine excitation.It can be concluded that the proposed approach achieves quite accurate RGA values with the advantage of exempting the user from deriving a complete parametric model of the plant. Hence, efforts of identifying the parameters of all MIMO subsystems can be saved by finding the parameters of the most significant subsystems of a multivariable system.
Godkänd; 2015; 20151027 (alikad); Nedanstående person kommer att hålla licentiatseminarium för avläggande av teknologie licentiatexamen. Namn: Ali Mohammed Hussein Kadhim Ämne: Reglerteknik/Control Engineering Uppsats: Estimation of the Dynamic Relative Gain Array for Control Configuration Selection Examinator: Professor Wofgang Birk, Institutionen för system- och rymdteknik, Avdelning: Signaler och system, Luleå tekniska universitet Diskutant: Associate Professor Hamid Reza Shaker, The Maersk Mc-Kinney Moller Institute, Denmark Tid: Onsdag 4 december 2015 kl 09.30 Plats: F531, Luleå tekniska universitet

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5

Franklin, Timothy C. "Linear System Analyses of the Role of Reflex Gain and Delay in a Dynamic Human Spine Model". Thesis, Virginia Tech, 2006. http://hdl.handle.net/10919/33605.

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Measurement studies have linked paraspinal muscle reflexes to low back pain. However, the role of reflexes in stabilizing the spine is not clear. Previous studies enlisted biomechanical models to aid in understanding of how intrinsic stiffness stabilizes the spine. This work expands these previous studies by modeling the neuromuscular dynamic control of the spine. The presence of delay in the reflexive system limits the availability of traditional stability analyses. However it is possible to investigate how reflex delay affects stability of the spine model using methods in linear time delayed stability. Such analyses find the maximum reflex delay, i.e., the delay margin for which stability is possible. Therefore a biomechanical model of the spine was developed that used these methods for stability. The model was able to demonstrate how reflex gains and delays affect stability. It was shown that increased proportional reflex gain reduced the amount of co-contraction required for stability. However, increased reflex gain required a reduced delay margin of the system. Differential reflex gain had no effect on the amount of co-contraction required for stability. However, it was shown to increase the delay margin for small gains. As the differential reflex gain approached the magnitude of intrinsic muscle damping the trend was reversed, and increased gain caused the delay margin to approach zero. Increased intrinsic muscle damping did not affect the minimum co-contraction required for stability, but was shown to increase the delay margin in all cases. This study provided a theoretical explanation for the role of reflexes in stabilizing the spine. Results agree with the trends in the published literature regarding patients with low-back pain. Specifically, these patients demonstrate abnormally larger reflex delay. To maintain stability, atypically small reflex gain is necessary. Compensatory co-contraction is required to offset the small reflex gain. Co-contraction and instability is observed in low back pain patients. The results presented here agree with measurement studies, and should aid in the development of hypotheses for future measurement studies.
Master of Science

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6

Chen, Lin. "A low power, high dynamic-range, broadband variable gain amplifier for an ultra wideband receiver". Texas A&M University, 2003. http://hdl.handle.net/1969.1/5843.

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A fully differential Complementary Metal-Oxide Semiconductor (CMOS) Variable Gain Amplifier (VGA) consisting of complementary differential pairs with source degeneration, a current gain stage with programmable current mirror, and resistor loads is designed for high frequency and low power communication applications, such as an Ultra Wideband (UWB) receiver system. The gain can be programmed from 0dB to 42dB in 2dB increments with -3dB bandwidth greater than 425MHz for the entire range of gain. The 3rd-order intercept point (IIP3) is above -13.6dBm for 1Vpp differential input and output voltages. These low distortion broadband features benefit from the large linear range of the differential pair with source degeneration and the low impedance internal nodes in the current gain stages. In addition, common-mode feedback is not required because of these low impedance nodes. Due to the power efficient complementary differential pairs in the input stage, power consumption is minimized (9.5mW) for all gain steps. The gain control scheme includes fine tuning (2dB/step) by changing the bias voltage of the proposed programmable current mirror, and coarse tuning (14dB/step) by switching on/off the source degeneration resistors in the differential pairs. A capacitive frequency compensation scheme is used to further extend the VGA bandwidth.

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7

Syed, Khalid Siraj. "A theoretical study of dynamic gain gratings and their application to self-adaptive laser oscillators". Thesis, Imperial College London, 1998. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.298865.

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8

Rubio, Pedro, Francisco Fernandez y Francisco Jimenez. "REAL TIME C BAND LINK BUDGET MODEL CALCULATION". International Foundation for Telemetering, 2016. http://hdl.handle.net/10150/624184.

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The purpose of this paper is to show the integration of the transmission gain values of a telemetry transmission antenna according to its relative position and integrate them in the C band link budget, in order to obtain an accuracy vision of the link. Once our C band link budget was fully performed to model our link and ready to work in real time with several received values (GPS position, roll, pitch and yaw) from the aircraft and other values from the Ground System (azimuth and elevation of the reception telemetry antenna), it was necessary to avoid a constant value of the transmitter antenna and estimate its values with better accuracy depending of the relative beam angles between the transmitter antenna and receiver antenna. Keeping in mind an aircraft is not a static telecommunication system it was necessary to have a real time value of the transmission gain. In this paper, we will show how to perform a real time link budget (C band).

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9

Cylc, Linda. "A VALUABLE TOOL TO HAVE WHEN WORKING WITH PSK DEMODULATORS IS A KNOWLEDGE OF ITS FUNCTIONALITY". International Foundation for Telemetering, 1998. http://hdl.handle.net/10150/609675.

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International Telemetering Conference Proceedings / October 26-29, 1998 / Town & Country Resort Hotel and Convention Center, San Diego, California
PSK demodulators have been an integral part of the signal recovery process for decades. Unless a person has designed a demodulator, how much can a person know or understand about its operation? Instruction on how to set up a demodulator’s parameters to acquire a signal is found in a manual. An explanation of why parameters are set a certain way to handle particular input signal characteristics is often not provided in a manual. This paper is designed to be a tool to aid engineers, technicians, and operators who utilize demodulators. Its purpose is to relay the functionality of a demodulator to a user so that he or she can take advantage of its control parameters and status feedback. Knowing the reasons why a demodulator is set to certain parameters may greatly reduce confusion when a system is not working properly. On site troubleshooting may be accomplished without the need to call the manufacturer of the product. Another advantage of understanding the operation will be recognized when interfacing with the manufacturer. A person will be able to relay the information to a design engineer more easily, and will understand more of the engineer’s feedback on the potential problem. Utilizing this paper as an aid to enhance operation of a PSK demodulator will bring a user one step closer to understanding the complexity of its design.

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10

Bernard, Pauline. "Synthèse d'observateur pour systèmes non linéaires". Thesis, Paris Sciences et Lettres (ComUE), 2017. http://www.theses.fr/2017PSLEM010/document.

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Contrairement aux systèmes linéaires, il n’existe pas de méthode systématique pour la synthèse d’observateurs pour systèmes non linéaires. Cependant, la synthèse peut être plus ou moins simple suivant les coordonnées choisies pour exprimer la dynamique. Des structures particulières, appelées formes canoniques, ont notamment été identifiées comme permettant la construction facile et directe d’un observateur. Une façon usuelle de résoudre ce problème consiste donc à chercher un changement de coordonnées réversible transformant l’expression de la dynamique dans l’une de ces formes canoniques, puis à synthétiser l’observateur dans ces coordonnées, et enfin à en déduire une estimation de l’état du système dans les coordonnées initiales par inversion de la transformation. Cette thèse contribue à chacune de ces trois étapes. Premièrement, nous montrons l’intérêt d’une nouvelle forme triangulaire avec des non linéarités continues (non Lipschitz). En effet, les systèmes observables pour toutes entrées, mais dont l'ordre d’observabilité différentielle est supérieur à la dimension du système, peuvent ne pas être transformables dans la forme triangulaire Lipschitz standard, mais plutôt dans une forme triangulaire "seulement continue". Le célèbre observateur grand gain n’est alors plus suffisant, et nous proposons d’utiliser plutôt des observateurs homogènes.Une autre forme canonique intéressante est la forme linéaire Hurwitz, qui admet un observateur trivial. La question de la transformation d’un système non linéaire dans une telle forme n’a été étudiée que pour les systèmes autonomes à travers les observateurs de Kazantzis-Kravaris ou de Luenberger. Nous montrons ici comment cette synthèse, consistant à résoudre une EDP, peut être étendue aux systèmes instationnaires/commandés. Quant à l’inversion de la transformation, cette étape est loin d’être triviale en pratique, surtout lorsque les espaces de départ et d’arrivée ont des dimensions différentes. En l’absence d’expression explicite et globale de l’inverse, l’inversion numérique repose souvent sur la résolution d’un problème de minimisation couteux en calcul. C’est pourquoi nous développons une méthode qui permet d’éviter l’inversion explicite de la transformation en ramenant la dynamique de l’observateur (exprimée dans les coordonnées de la forme canonique) dans les coordonnées initiales du système. Ceci passe par l’ajout de nouvelles coordonnées et par l’augmentation d’une immersion injective en un difféomorphisme surjectif. Enfin, dans une partie totalement indépendante, nous proposons aussi des résultats concernant l’estimation de la position du rotor d’un moteur synchrone à aimant permanent en l’absence d’informations mécaniques (sensorless) et lorsque des paramètres tels que la résistance ou le flux de l’aimant sont inconnus. Ceci est illustré par des simulations sur données réelles
Unlike for linear systems, no systematic method exists for the design of observers for nonlinear systems. However, observer design may be more or less straightforward depending on the coordinates we choose to express the system dynamics. In particular, some specific structures, called canonical forms, have been identified for allowing a direct and easier observer construction. It follows that a common way of addressing the problem consists in looking for a reversible change of coordinates transforming the exression of the system dynamics into one of those canonical forms, design an observer in those coordinates, and finally deduce an estimate of the system state in the initial coordinates via inversion of the transformation. This thesis contributes to each of those three steps.First, we show the interest of a new triangular canonical form with continuous (non-Lipschitz) nonlinearities. Indeed, we have noticed that systems which are observable for any input but with an order of differential observability larger than the system dimension, may not be transformable into the standard Lipschitz triangular form, but rather into an "only continuous" triangular form. In this case, the famous high gain observer no longer is sufficient, and we propose to use homogeneous observers instead.Another canonical form of interest is the Hurwitz linear form which admits a trivial observer. The question of transforming a nonlinear system into such a form has only been addressed for autonomous systems with the so-called Lunberger or Kazantzis-Kravaris observers. This design consists in solving a PDE and we show here how it can be extended to time-varying/controlled systems.As for the inversion of the transformation, this step is far from trivial in practice, in particular when the domain and image spaces have different dimensions. When no explicit expression for a global inverse is available, numerical inversion usually relies on the resolution of a minimization problem with a heavy computational cost. That is why we develop a method to avoid the explicit inversion of the transformation by bringing the observer dynamics (expressed in the canonical form coordinates) back into the initial system coordinates. This is done by dynamic extension, i-e by adding some new coordinates to the system and augmenting an injective immersion into a surjective diffeomorphism.Finally, in a totally independent part, we also provide some results concerning the estimation of the rotor position of a permanent magnet synchronous motors without mechanical information (sensorless) and when some parameters such as the magnet flux or the resistance are unknown. We illustrate this with simulations on real data

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11

Dasgupta, Abhijeet. "High efficiency S-Band vector power modulator design using GaN technology". Thesis, Limoges, 2018. http://www.theses.fr/2018LIMO0021/document.

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L’évolution des systèmes de télécommunications, liée à une demande sans cesse croissante en termes de débit et de volume de données, se concrétise par le développement de systèmes proposant des bandes passantes très larges, des modulations à très hautes efficacités spectrales, de la flexibilité en puissance et en fréquence d’émission. Par ailleurs, la mise en œuvre de ces dispositifs doit se faire avec un souci permanent d’économie d’énergie d’où la problématique récurrente de l’amplification de puissance RF qui consiste à allier au mieux rendement, linéarité et bande passante. L’architecture conventionnelle d’une chaine d’émission RF consiste dans une première étape à réaliser l’opération de modulation-conversion de fréquence (Modulateur IQ) puis dans une deuxième étape l’opération de conversion d’énergie DC-RF (Amplificateur de Puissance), ces deux étapes étant traditionnellement traitées de manière indépendante. L’objectif de ces travaux de thèse est de proposer une approche alternative qui consiste à combiner ces deux opérations dans une seule et même fonction : le modulateur vectoriel de puissance à haute efficacité énergétique. Le cœur du dispositif, conçu en technologie GaN, repose sur un circuit à deux étages de transistors HEMT permettant d’obtenir un gain en puissance variable en régime de saturation. Il est associé à un modulateur de polarisation multi-niveaux spécifique également en technologie GaN. Le dispositif réalisé a permis de générer directement, à une fréquence de 2.5 GHz, une modulation vectorielle 16QAM (100Msymb/s) de puissance moyenne 13 W, de puissance crête 25W avec un rendement global de 40% et une linéarité mesurée par un EVM à 5%
The evolution of telecommunications systems, linked to a constantly increasing demand in terms of data rate and volume, leads to the development of systems offering very wide bandwidths, modulations with very high spectral efficiencies, increased power and frequency flexibilities in transmitters. Moreover, the implementation of such systems must be done with a permanent concern for energy saving, hence the recurring goal of the RF power amplification which is to combine the best efficiency, linearity and bandwidth. Conventional architectures of RF emitter front-ends consist in a first step in performing the frequency modulation-conversion operation (IQ Modulator) and then in a second step the DC-RF energy conversion operation (Power Amplifier), these two steps being usually managed independently. The aim of this thesis is to propose an alternative approach that consists in combining these two operations in only one function: a high efficiency vector power modulator. The core of the proposed system is based on a two-stage GaN HEMT circuit to obtain a variable power gain operating at saturation. It is associated with a specific multi-level bias modulator also design using GaN technology. The fabricated device generates, at a frequency of 2.5 GHz, a 16QAM modulation (100Msymb/s) with 13W average power, 25W peak power, with an overall efficiency of 40% and 5% EVM

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12

Ren, Zheng. "Contribution au développement du transistor bipolaire à fort gain et d'un interrupteur bidirectionnel à quatre quadrants". Thesis, Tours, 2018. http://www.theses.fr/2018TOUR4031/document.

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Afin de répondre aux besoins en management efficace de l’énergie électrique dans les bâtiments intelligents, le laboratoire GREMAN a proposé une nouvelle topologie d’interrupteur bidirectionnel de 600 V nommé TBBS. Les études antérieures ont validé la bidirectionnalité en courant et en tension de cette nouvelle topologie. Les travaux de recherche menées dans cette thèse avaient pour l’objectif d’approfondir, de compléter nos connaissances sur ce nouvel interrupteur bidirectionnel ainsi que sur le transistor bipolaire à fort gain. Le premier chapitre introduit le fonctionnement principal du TBBS et sa modélisation physique sous un environnement de simulation à éléments finis. Le deuxième chapitre présente le travail concernant la caractérisation expérimentale du TBBS et du transistor bipolaire à fort gain sous température contrôlée. Enfin la modélisation électrique du TBBS et du transistor bipolaire à fort gain est présentée dans le troisième et dernier chapitre
In order to meet the requirement of more efficient electrical energy management for intelligent buildings, a new 600V bidirectional switch, named as TBBS, has been proposed by the GREMAN laboratory. Previous studies have validated the current and voltage bidirectionality of this newly proposed topology. The research work carried out in this thesis deals with a deeper and more comprehensive study of this bidirectional switch and its elementary component - the High-gain bipolar juncion transistor. The first chapter introduces the operation of the TBBS and its physical modeling in a finite element simulation environment. The second chapter presentes the research work related to the experimental caracterisation of the TBBS and the High-gain bipolar junction transistor. At last the third chapter deals with the electrical modeling of these two bipolar components

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13

Tergny, Guillaume. "Allocation dynamique de portefeuille avec profil de gain asymétrique : risk management, incitations financières et benchmarking". Phd thesis, Conservatoire national des arts et metiers - CNAM, 2011. http://tel.archives-ouvertes.fr/tel-00629049.

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Les gérants de portefeuille pour compte de tiers sont souvent jugés par leur performance relative à celle d'un portefeuille benchmark. A ce titre, ils sont amenés très fréquemment à utiliser des modèles internes de "risk management" pour contrôler le risque de sous-performer le benchmark. Par ailleurs, ils sont de plus en plus nombreux à adopter une politique de rémunération incitative, en percevant une commission de sur-performance par rapport au benchmark. En effet, cette composante variable de leur rémunération leur permet d'augmenter leur revenu en cas de sur-performance sans contrepartie en cas de sous-performance. Or de telles pratiques ont fait récemment l'objet de nombreuses polémiques : la période récente de crise financière mondiale a fait apparaître certaines carences de plusieurs acteurs financiers en terme de contrôle de risque ainsi que des niveaux de prise de risque et de rémunération jugés excessifs. Cependant, l'étude des implications de ces pratiques reste un thème encore relativement peu exploré dans le cadre de la théorie classique des choix dynamiques de portefeuille en temps continu. Cette thèse analyse, dans ce cadre théorique, les implications de ces pratiques de "benchmarking" sur le comportement d'investissement de l'asset manager. La première partie étudie les propriétés de la stratégie dynamique optimale pour l'asset manager concerné par l'écart entre la rentabilité de son portefeuille et celle d'un benchmark fixe ou stochastique (sur ou sous-performance). Nous considérons plusieurs types d'asset managers, caractérisés par différentes fonctions d'utilité et qui sont soumis à différentes contraintes de risque de sous-performance. Nous montrons en particulier quel est le lien entre les problèmes d'investissement avec prise en compte de l'aversion à la sous-performance et avec contrainte explicite de "risk management". Dans la seconde partie, on s'intéresse à l'asset manager bénéficiant d'une rémunération incitative (frais de gestion variables, bonus de sur-performance ou commission sur encours additionnelle). On étudie, selon la forme de ses incitations financières et son degré d'aversion à la sous-performance, comment sa stratégie d'investissement s'écarte de celle de l'investisseur (ou celle de l'asset manager sans rémunération incitative). Nous montrons que le changement de comportement de l'asset manager peut se traduire soit par une réduction du risque pris par rapport à la stratégie sans incitation financière soit au contraire par une augmentation de celui-ci. Finalement, nous montrons en quoi la présence de contraintes de risque de sous-performance, imposées au gérant ou traduisant son aversion à la sous-performance, peut être bénéfique à l'investisseur donnant mandat de gestion financière.

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14

Martins, Merino Ricardo [Verfasser], Fred [Akademischer Betreuer] [Gutachter] Wolf, Walter [Gutachter] Stühmer, Andreas [Gutachter] Neef, Jochen [Gutachter] Staiger, Siegrid [Gutachter] Löwel y Oliver [Gutachter] Schlüter. "Determination of the Dynamic Gain Function of Cortical Interneurons with distinct Electrical Types / Ricardo Martins Merino ; Gutachter: Fred Wolf, Walter Stühmer, Andreas Neef, Jochen Staiger, Siegrid Löwel, Oliver Schlüter ; Betreuer: Fred Wolf". Göttingen : Niedersächsische Staats- und Universitätsbibliothek Göttingen, 2017. http://d-nb.info/1130868303/34.

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15

Berg, Miguel. "Radio Resource Management in Bunched Personal Communication Systems". Doctoral thesis, KTH, Signals, Sensors and Systems, 2002. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-3316.

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The traditional way of increasing capacity in a wirelesscommunication system has been cell splitting and fixedchannel-allocation based on prediction tools. However, theplanning complexity increases rapidly with the number of cellsand the method is not suitable for the large temporal andspatial traffic variations expected in the future. A lot ofresearch has therefore been performed regarding adaptivechannel allocation, where a channel can be used anywhere aslong as the signal-to-interference ratio (SIR) is acceptable. Acommon opinion is that these solutions must be decentralizedsince a centralized one would be overly complex.

In this thesis, we study the locally centralizedbunch conceptfor radio resource management (RRM) in aManhattan environment and show that it can give a very highcapacity both for outdoor users and for indoor users covered byoutdoor base stations. We show how measurement limitations anderrors affect the performance and wepropose methods to handlethese problems, e.g. averaging of measured values, robustchannel selection algorithms, and increased SIR margins. Wealso study the computational and signaling complexities andshow that they can be reduced by splitting large bunches, usingsparse matrix calculations, and by using a simplified admissionalgorithm. However, a reduction of the complexity often means areduction of the system capacity.

The measurements needed for RRM can also be used to find amobile terminal's geographical position. We propose and studysome simple yet accurate methods for this purpose. We alsostudy if position information can enhance RRM as is oftensuggested in the literature. In the studied scenario, thisinformation seems to be of limited use. One possible use is toestimate the mobile user's speed, to assist handover decisions.Another use is to find the location of user hotspots in anarea, which is beneficial for system planning.

Our results show that the bunch concept is a promisingcandidate for radio resource management in future wirelesssystems. We believe that the complexity is manageable and themain price we have to pay for high capacity is frequentreallocation of connections.

Keywords:bunch concept, radio resource management,network-assisted resource management, base station selection,dynamic channel allocation, DCA, channel selection,least-interfered, interference avoidance, interferenceaveraging, handover, power control, path-loss measurements,signal strength, link-gain matrix, TD-CDMA, UTRA TDD, Manhattanscenario, microcells, mobile positioning, position accuracy,trilateration, triangulation, speed estimation

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16

Mehrez, Fatima. "Design and test of a readout ASIC for a SiPM - based camera : ALPS (ASIC de lecture pour un photodétecteur SiPM)". Thesis, Université Grenoble Alpes (ComUE), 2015. http://www.theses.fr/2015GREAT131/document.

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Cette thèse est la R&D de l’électronique de front-end destinée à la camera de deuxième génération du télescope de grande taille LST de projet CTA, étant basée sur les détecteurs de type SiPM. Cette étude rassemble des équipes du LAPP, de l’université de Padoue, de l’INFN et du MPI de Munich. La première partie de cette thèse porte sur les tests de caractérisations d’une matrice de 16 SiPMs fabriquée par Hamamatsu. Les résultats de ces tests ont souligné les avantages qui pourraient être apportés par l’utilisation de tels détecteurs. Un cahier des charges pour l’électronique a été défini à l’issue de ces tests. Notamment, une nécessité de corriger la dispersion en gain entre les 16 pixels qui a été trouvée d’environ 10%. La seconde partie est la conception d’un circuit intégré (ASIC) qui pourrait lire les signaux des pixels -SiPM avec la moindre perturbation possible de fonctionnement du détecteur. Cet ASIC inclut des fonctions de contrôle (slow control) qui permettent l’ajustement de gain des pixels, l’amélioration de l’uniformité de gain et la possibilité de supprimer les canaux bruyants ou encore même le contournement du processus de contrôle de gain. Ces fonctionnalités peuvent unifier le gain de 16 canaux. Les sorties des 16 canaux seront sommées pour en faire deux signaux seulement à la sortie de l’ASIC. Ces deux signaux, un sur le haut gain et l’autre sur le bas gain seront fournis au système d’acquisition qui suivra l’ASIC. Une fonction de déclenchement génèrera un signal de trigger qui sera ainsi transmis au système d’acquisition. Cet ASIC a été réalisée avec la technologie AMS 0.35um BiCMOS. Les simulations ont montré une gamme dynamique linéairement couverte jusqu’à 2000 photoélectrons et la possibilité de mesurer le photoélectron unique grâce au bon rapport signal sur bruit électronique. Les tests au laboratoire confirment une grande partie de ces résultats
This thesis is the R&D on front-end electronics for a second generation camera based on the SiPM detectors for the Large Size Telescope (LST) of the CTA project. It is a part of the SiPM collaboration involving the LAPP, the University of Padua, the INFN and the MPI in Munich. The first part of the thesis is the characterization of an array of 16 SiPMs from Hamamatsu. The study proves the advantages of using such detectors in the LST. It defines the specifications of the readout electronics that are the aim of this work. Especially that it should ameliorate the gain dispersion of the 16 pixels that was found of about 10%. The second part is the design of the readout ASIC. The scheme tends to measure the SiPMs’ signals with minimum disturbance of the detector. It integrates slow control facilities that adjust the detector’s gain, minimize the dispersion in gain and provide the possibility of deleting noisy channels or even completely jumping over the control process. These facilities could perfectly get rid of the gain dispersion. Outputs of the 16 pixels will be summed on both high gain and low gain so that only two signals are delivered to the acquisition system that follows. A trigger function will also generate a trigger signal to the acquisition system. The choice was made to realize this ASIC according to the rules of the AMS 0.35um BiCMOS technology. Simulation shows a linearly-covered dynamic range up to 2000 photoelectrons with good signal to noise ratio that allows the measurement of the single photoelectron. Laboratory tests confirm a great part of these results

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17

Laferriere, Patrick. "Gain Dynamics of the N2+ Air Laser". Thesis, Université d'Ottawa / University of Ottawa, 2018. http://hdl.handle.net/10393/38025.

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Lasing from femtosecond laser filaments is a relatively new field of study that has been studied since its first observation in 2003. Such lasing effect is of interest to the scientific community due to its possible application in remote sensing. This thesis studies the lasing dynamics of the excited molecular nitrogen ion N2+ which emits primarily at 391 nm and 428 nm wavelengths. We start by studying the ellipticity dependence of the gain from filaments in ambient air. We then study the ellipticity dependence in a vacuum in a supersonic gas jet to remove the complexity of filamentation. We show that recollision doesn't play a significant role in creating a population inversion by comparing the ellipticity dependence of the gain and high harmonic generation. The rest of this thesis is devoted to shining some light on another possible mechanism. We characterize the gain by its temporal profile, jet position dependence, and density dependence.

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18

Sanchez, Ayala Gerardo. "Centralized Control of Power System Stabilizers". Diss., Virginia Tech, 2014. http://hdl.handle.net/10919/51754.

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This study takes advantage of wide area measurements to propose a centralized nonlinear controller that acts on power system stabilizers, to cooperatively increase the damping of problematic small signal oscillations all over the system. The structure based on decision trees results in a simple, efficient, and dependable methodology that imposes much less computational burden than other nonlinear design approaches, making it a promising candidate for actual implementation by utilities and system operators. Details are given to utilize existing stabilizers while causing minimum changes to the equipment, and warranting improvement or at least no detriment of current system behavior. This enables power system stabilizers to overcome their inherent limitation to act only on the basis of local measurements to damp a single target frequency. This study demonstrates the implications of this new input on mathematical models, and the control functionality that is made available by its incorporation to conventional stabilizers. In preparation of the case of study, a heuristic dynamic reduction methodology is introduced that preserves a physical equivalent model, and that can be interpreted by any commercial software package. The steps of this method are general, versatile, and of easy adaptation to any particular power system model, with the aggregated value of producing a physical model as final result, that makes the approach appealing for industry. The accuracy of the resulting reduced network has been demonstrated with the model of the Central American System.
Ph. D.

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19

Kursu, Sami. "Adaptiv nivåreglering: Dynamisk expansion av ljudsignaler i en reell arbetsmiljö". Thesis, Interactive Institute Piteå, 2013. http://urn.kb.se/resolve?urn=urn:nbn:se:ri:diva-24267.

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20

Wuestner, Sebastian Marc. "Gain and plasmon dynamics in active nanoplasmonic metamaterials". Thesis, Imperial College London, 2012. http://hdl.handle.net/10044/1/10543.

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Optical metamaterials are composite media that can be made to exhibit striking optical properties, some of which are not observed in nature, such as a negative refractive index. This advanced control over the electromagnetic response is enabled by subwavelength building blocks, most often based on metals. While metallic structural features provide the necessary resonant interaction with light, they also give rise to dissipative losses, which can interfere with the desired performance in applications. The incorporation of optical gain has emerged as a promising way to improve the loss-encumbered operation. It is this enhancement of metamaterials by gain, which is at the heart of this thesis. Three relevant topics will be considered: loss compensation, coherent amplification and lasing dynamics. The numerical studies presented here focus on the double-fishnet structure, a metamaterial exhibiting a negative refractive index at optical wavelengths. First, it is shown that loss compensation via optical gain is possible and that, in addition, it constitutes a practical means to overcome dissipative losses. Compensation of losses in combination with a negative refractive index is observed, disproving theoretical claims that rule out such behaviour. As a natural continuation, the characteristics above the threshold of amplification are investigated, i.e., when dissipative losses are overcompensated. By defining and analysing an effective rate balance, radiative outcoupling is found to be non-negligible. Hence, contrary to quasistatic predictions for nanoplasmonic metamaterials, a window of amplification opens. Beyond the regime of amplification, when gain exceeds both dissipative losses and radiative outcoupling, lasing instabilities occur. Nonlinear mode dynamics arise and it is shown that sole bright emission can be achieved despite the strong competition from a dark plasmonic mode. The numerical studies performed here shed new light on the complex physics arising from the nonlinear dynamic interaction of optical gain and resonant modes in nanoplasmonic metamaterials.

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21

Archundia-Berra, Luis. "EXTERNAL CAVITY MULTIWAVELENGTH SEMICONDUCTOR MODE-LOCKED LASER GAIN DYNAMICS". Doctoral diss., University of Central Florida, 2006. http://digital.library.ucf.edu/cdm/ref/collection/ETD/id/3078.

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External cavity semiconductor mode-locked lasers can produce pulses of a few picoseconds. The pulses from these lasers are inherently chirped with a predominant linear chirp component that can be compensated resulting in sub-picosecond pulses. External cavity semiconductor mode-locked lasers can be configured as multiwavelength pulse sources and are good candidates for time and wavelength division multiplexing applications. The gain medium in external cavity semiconductor mode-locked lasers is a semiconductor optical amplifier (SOA), and passive and hybrid mode-locked operation are achieved by the introduction of a saturable absorber (SA) in the laser cavity. Pump-probe techniques were used to measure the intracavity absorption dynamics of a SA in an external cavity semiconductor mode-locked laser and the gain dynamics of a SOA for the amplification of diverse pulses. The SOA gain dynamics measurements include the amplification of 750 fs pulses, 6.5 ps pulses, multiwavelength pulses and the intracavity gain dynamics of an external cavity multiwavelength semiconductor mode-locked laser. The experimental results show how the inherent chirp on pulses from external cavity semiconductor mode-locked lasers results in a slow gain depletion without significant fast gain dynamics. In the multiwavelength operation regime of these lasers, the chirp broadens the temporal pulse profile and decreases the temporal beating resulting from the phase correlation among wavelength channels. This results in a slow gain depletion mitigating nonlinearities and gain competition among wavelength channels in the SOA supporting the multiwavelength operation of the laser. Numerical simulations support the experimental results.
Ph.D.
Department of Physics
Optics and Photonics
Optics

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22

Bream, Philip John. "Nonequilibrium carrier dynamics and gain in semiconductor quantum wells". Thesis, University of Nottingham, 2006. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.438558.

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23

Schmiel, David R. "Effects of variations in controller gains on the dynamics of magnetic bearings". Thesis, This resource online, 1996. http://scholar.lib.vt.edu/theses/available/etd-11182008-063516/.

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24

Fonseca, Daniel Guerra Vale da. "Modelagem e controle adaptativo de uma planta did?tica de n?vel com instrumenta??o industrial". Universidade Federal do Rio Grande do Norte, 2012. http://repositorio.ufrn.br:8080/jspui/handle/123456789/15446.

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Made available in DSpace on 2014-12-17T14:56:07Z (GMT). No. of bitstreams: 1 DanielGVF_DISSERT.pdf: 2881772 bytes, checksum: 5236953fb6bb70560393eeeaa01f96f9 (MD5) Previous issue date: 2012-08-31
Conselho Nacional de Desenvolvimento Cient?fico e Tecnol?gico
The control, automation and optimization areas help to improve the processes used by industry. They contribute to a fast production line, improving the products quality and reducing the manufacturing costs. Didatic plants are good tools for research in these areas, providing a direct contact with some industrial equipaments. Given these capabilities, the main goal of this work is to model and control a didactic plant, which is a level and flow process control system with an industrial instrumentation. With a model it is possible to build a simulator for the plant that allows studies about its behaviour, without any of the real processes operational costs, like experiments with controllers. They can be tested several times before its application in a real process. Among the several types of controllers, it was used adaptive controllers, mainly the Direct Self-Tuning Regulators (DSTR) with Integral Action and the Gain Scheduling (GS). The DSTR was based on Pole-Placement design and use the Recursive Least Square to calculate the controller parameters. The characteristics of an adaptive system was very worth to guarantee a good performance when the controller was applied to the plant
As ?reas de controle, automa??o e otimiza??o contribuem para a melhoria dos processos utilizados pelas ind?strias, permitindo uma linha de produ??o r?pida, aprimorando a qualidade do produto final e reduzindo os custos de produ??o. Boas ferramentas para o desenvolvimento de pesquisas nestas ?reas s?o as plantas did?ticas, pois proporcionam um contato direto com equipamentos semelhantes ou at? mesmo usados no setor industrial. Em vista dessas capacidades, o objetivo deste trabalho ? modelar e controlar uma planta did?tica que consiste de um sistema de controle de processo para vaz?o e n?vel com instrumenta??o industrial. Com o modelo ? poss?vel construir um simulador capaz de permitir estudos a respeito do funcionamento do sistema, sem os gastos com a opera??o do processo real. ? o caso de experimentos com controladores, que podem ser testados diversas vezes antes de serem efetivamente utilizados no processo real. Dentre os diversos tipos de controladores existentes, foi dado foco aos de tipo adaptativo, principalmente ao auto-sintoniz?vel direto (Direct Self-Tuning Regulator DSTR) com a??o integral e ao controlador com Escalonamento de Ganho (Gain Scheduling GS). O controlador DSTR foi projetado com base no m?todo de posicionamento de p?los e teve seus par?metros calculados atrav?s da t?cnica dos m?nimos quadrados recursivos. As caracter?sticas dos sistemas adaptativos foram de grande valia para garantir um desempenho satisfat?rio dos controladores, quando aplicados ? planta

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25

Talli, Giuseppe. "Amplified spontaneous emission and gain dynamics in semiconductor optical amplifiers". Thesis, University of Essex, 2004. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.397730.

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26

Charles, William G. "Dynamic walking models to understand asymmetric gait characteristics". Thesis, Swansea University, 2018. https://cronfa.swan.ac.uk/Record/cronfa48133.

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Passive dynamic walking models remarkably predict gait behaviour such as walk-run transition speeds, preferred step length, stride frequencies and - with the inclusion of springs - ground reaction forces. Muscular or neurological conditions may lead to asymmetric walking characteristics that, in turn, come with long term health risks. Gait analysis may be used to understand an individual patient's conditions to help rehabilitate them. However, people adapt their kinematic and kinetic walking patterns so it can be hard to distinguish the eﬀects of gait alterations such as inertial imbalance or injury. In this thesis a compass walking model with no active controllers is explored to understand the dynamics of gait. To help us interpret the eﬀects of mass imbalance with a prosthetic foot or orthotic device, asymmetric loading conditions are investigated. A simple spring-mass walking model is used to explore the eﬀects of altered touch-down angles and eﬀective leg stiﬀness to see if these are used as strategies to alter the characteristics of gait. Results show that an asymmetric touch-down angle alters step length while retaining a symmetric stance time. A hybrid model is then derived with springs to emulate human-like ground reaction forces and asymmetric inertial loading of the legs. Results support previous research that push-oﬀ from the trailing leg propels the leg mass more than the body mass. Higher rates of joint forces, larger step lengths and a longer stance time on the residual limb may be due to the prosthetic leg stiﬀness or the higher location of centre-of-mass. These results help us understand how the dynamic components aﬀect gait characteristics such as step length, stance time and walking speeds. This work is motivated by the needs of persons with disabilities and by the desire to understand human walking.

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27

Giessen, Harald Willi. "Ultrafast carrier and gain dynamics in strongly confined semiconductor quantum dots". Diss., The University of Arizona, 1995. http://hdl.handle.net/10150/187341.

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This thesis investigates the carrier and gain dynamics of semiconductor quantum dots in the strong quantum confinement regime (i.e. the dot radius is smaller than the bulk excitonic Bohr radius). The materials under investigation are InP and CdSe. We can summarize our findings as follows: For the first time, the quantum confined ground state in InP quantum dots has been observed at room temperature by femtosecond spectral holeburning. This is the first confirmation of the observation of a strongly confined quantum dot made of III-V semiconductor materials. In CdSe quantum dots with a radius of half the bulk exciton Bohr radius, the carrier and gain dynamics have been investigated. The predicted phonon bottleneck, which should slow down carrier relaxation up to nanoseconds, has not been found. The carrier relaxation rates are rather on the order of 1 eV/ps. Gain has been found for the first time in strongly confined quantum dots. The existence of gain was proven by spectral holeburning in the gain region. The gain buildup and decay dynamics have been studied on a femtosecond and picosecond timescale. A multi-level model including biexcitons accounts for the gain formation. The model has been confirmed by three-beam spectral holeburning experiments and femtosecond pump-probe experiments with circularly polarized light. Some quantum dots did not show gain under high optical excitation but instead exhibited photodarkening. The carrier separation and localization dynamics of this photodarkening process has been studied on a femtosecond timescale. For the first time, the shift of the bleaching towards lower energy during the localization process could be observed on a femtosecond timescale. Finally, pulse propagation in bulk CdSe at multiple Pi-pulses has been studied. For the first time, strong evidence for the observation of self induced transparency in semiconductors has been found. Also, optical precursors, probably of nonlinear nature, have been found.

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28

Muratagic, Haris. "Passive Symmetry in Dynamic Systems and Walking". Scholar Commons, 2015. http://scholarcommons.usf.edu/etd/5998.

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The ubiquitous nature of symmetry lends itself to be taken for granted, however the breath of research on symmetry encompasses several disciplines. In engineering, studies centered on symmetry often address issues in dynamic systems theory, robotics, and gait rehabilitation. This thesis presents findings on two specific topics dealing with passively induced symmetry; dissimilar rotating systems and human gait. Past studies on passive symmetry in dynamic systems often incorporate physical coupling or a controller. This thesis presents a technique to passively induce symmetry between two dissimilar systems that are not physically connected. This work also presents a human gait study consisting of several elements that merge to provide a unique look at how walking symmetry and altered physical parameters (leg length and added weight) of the lower limbs are related. One aspect of this thesis shows the successful development of a general method to induce synchronization between any two dissimilar, uncoupled, rotating systems given the same degrees of freedom, initial angular dynamics, and applied torque. This method is validated with a simulation and subsequent comparison with two physical experiments. The results are in agreement, with slight variations due to the friction and damping of the physical systems. This is further expanded to include the induced symmetry of two systems that experience an external collision. Due to the highly non-linear nature of such systems, an analytical solution was not found; instead a numerical solution is presented that resulted in partial symmetry between systems. The gait study demonstrated that weighted walking and altered leg length have both independent and combined spatio-temporal effects on lower limb symmetry. While altered leg length alone resulted in higher gait asymmetry, the combination of the two physical changes increases this asymmetry to affect the same limb. This study also showed that cognitive and physically distracted walking does not have an added effect to the gait symmetry with passive physical changes. In addition, this study was able to demonstrate that the arm swinging that occurs during natural walking does not significantly alter spatial or temporal gait parameters.

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29

Le, Riche Antoine. "Commerce international dans le modèle bi-sectoriel à générations imbriquées". Thesis, Aix-Marseille, 2014. http://www.theses.fr/2014AIXM2023/document.

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Cette thèse comporte trois essais sur l'existence de cycles endogènes sous efficacité dynamique et compte deux thèmes. Le premier thème est traité dans le chapitre 2 et aborde la relation entre la structure industrielle et l'émergence de fluctuations endogènes. Le deuxième sujet est examiné dans les chapitres 3 et 4, et tente d'améliorer notre compréhension du rôle du commerce international sur l'existence de cycles endogènes.La première contribution analyse dans quelle mesure l'existence de bien durable et non-durable est associée à l'occurrence de cycles endogènes sous efficacité dynamique. Les résultats indiquent que des cycles endogènes existent si la part de la consommation des jeunes allouée au bien non durable est assez petite. Nous démontrons qu'une politique de stabilisation basée sur des taxes et transferts forfaitaires permet dans un même temps d'augmenter le bien-être des agents et de supprimer l'existence des cycles.La seconde contribution considère un modèle à générations imbriquées à deux facteurs, deux biens et deux pays. Cette approche est basée sur l'hypothèse d'immobilité des facteurs de production entre pays. On suppose également que les pays sont identiques en tout point excepté en leur taux d'escompte. Nous établissons à l'aide d'une simulation numérique que des cycles à deux périodes se propagent d'un pays à l'autre.La troisième contribution se situe dans un cadre proche du modèle du chapitre 3 mais se focalise sur des différences technologiques entre pays. Nous mettons en évidence par le biais de simulations numériques que le commerce international peut générer des cycles à deux périodes qui n'existaient pas en économie fermée
This dissertation consists of three essays on the existence of endogenous cycles under dynamic efficiency and covers two different topics. The first one developed in chapter 2 addresses the relation between the structure of production and the occurrence of endogenous fluctuations. The second topic is developed in chapters 3 and 4, and tries to better understand the role of international trade on the emergence of sunspot cycles. These chapters explain that international trade may have a destabilizing effect.Chapter 2 examines how the existence of durable and non-durable goods are associated with the occurrence of endogenous cycles with dynamic efficiency. Main results indicate that sunspot fluctuations exist if young agents consume less non-durable goods than old agents. In this context, we show that a stabilization policy based on lump-sum taxes and lump-sum transfers allows to increase the welfare of agents and eliminate the existence of endogenous cycles.Chapter 3 analyzes a two-factor, two-good, two-country overlapping generations model. We assume that countries differ only with respect to their discount rate. We suppose that the factor of production are immobile across countries. Using a numerical simulation, we show that period-two cycles spread from one country to another.Chapter 4 considers a framework similar to the model of chapter 3 but with focus on asymmetric technology. We show through numerical simulations that the opening to international trade can create two-period cycles that can exist in the world economy even though the closed-economy equilibrium in each country is saddle-point stable

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30

Wellman, Brandon. "Root Locus Techniques With Nonlinear Gain Parameterization". UKnowledge, 2012. http://uknowledge.uky.edu/me_etds/21.

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This thesis presents rules that characterize the root locus for polynomials that are nonlinear in the root-locus parameter k. Classical root locus applies to polynomials that are affine in k. In contrast, this thesis considers polynomials that are quadratic or cubic in k. In particular, we focus on constructing the root locus for linear feedback control systems, where the closed-loop denominator polynomial is quadratic or cubic in k. First, we present quadratic root-locus rules for a controller class that yields a closed-loop denominator polynomial that is quadratic in k. Next, we develop cubic root-locus rules for a controller class that yields a closed-loop denominator polynomial that is cubic in k. Finally, we extend the quadratic root-locus rules to accommodate a larger class of controllers. We also provide controller design examples to demonstrate the quadratic and cubic root locus. For example, we show that the triple integrator can be high-gain stabilized using a controller that yields a closed-loop denominator polynomial that is quadratic in k. Similarly, we show that the quadruple integrator can be high-gain stabilized using a controller that yields a closed-loop denominator polynomial that is cubic in k.

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31

Nash, Jason Mark. "Evidence gathering for dynamic feature extraction". Thesis, University of Southampton, 1999. https://eprints.soton.ac.uk/253031/.

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32

Biswas, Ajoy. "Dynamic gait stability index using a fuzzy logic model". Thesis, University of Ottawa (Canada), 2006. http://hdl.handle.net/10393/27334.

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The field of physical rehabilitation needs a quantitative technique for measuring dynamic gait stability (walking stability) to make decisions regarding treatment, assistive devices, potential for falls, and to track progress during rehabilitation. This measure should be easily applied in a clinical setting, valid across physical disabilities, and must provide a quantitative index that can be used for comparisons over a range of tasks and environments. This research project developed and evaluated a gait stability index using a portable pressure measurement system. This study examined current stability analysis methods and evaluated dynamic gait stability assessment parameters. Six gait parameters were identified and extracted from a commercial foot pressure measurement system (F-Scan). A fuzzy logic controller combined the six parameters and generated an index value. Fifteen healthy subjects were evaluated at four stability levels. All parameter combinations (57 indices in total) were assessed to isolate the most effective index.

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33

Massenzo, Trisha J. "An Investigation of Kinetic Visual Biofeedback on Dynamic Stance Symmetry". VCU Scholars Compass, 2016. http://scholarscompass.vcu.edu/etd/4661.

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The intent of the following research is to utilize task-specific, constraint-induced therapies and apply towards dynamic training for symmetrical balance. Modifications to an elliptical trainer were made to both measure weight distributions during dynamic stance as well as provide kinetic biofeedback through a man-machine interface. Following a review of the background, which includes research from several decades that are seminal to current studies, a design review is discussed to cover the design of the modified elliptical (Chapter 2). An initial study was conducted in a healthy sample population in order to determine the best visual biofeedback representation by comparing different man-machine interfaces (Chapter 3). Index of gait symmetry measures indicated that one display interface optimized participant performance during activity with the modified elliptical trainer. A second study was designed to determine the effects of manipulating the gain of the signal to encourage increased distribution towards the non-dominant weight bearing limb. The purpose of the second study was to better understand the threshold value of gain manipulation in a healthy sample set. Results analyzing percentage error as a measure of performance show that a range between 5-10% allows for a suitable threshold value to be applied for participants who have suffered a stroke. A final study was conducted to apply results/knowledge from the previous two studies to a stroke cohort to determine short-term carryover following training with the modified elliptical trainer. Data taken from force measurements on the elliptical trainer suggest that there was carryover with decreased error from pre to post training. For one participant GaitRite® data show a significant difference from pre to post measurements in single limb support. The results of the research suggest that visual biofeedback can improve symmetrical performance during dynamic patterns. For a better understanding of visual biofeedback delivery, one display representation proved to be beneficial compared to the others which resulted in improved performance. Results show that healthy human participants can minimize error with visual biofeedback and continue minimizing error until a threshold value of 10%. Finally, results have shown promise towards applying such a system for kinetic gait rehabilitation.

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34

Cooney, Ryan. "Charge carrier dynamics and the development of optical gain in semiconductor quantum dots". Thesis, McGill University, 2010. http://digitool.Library.McGill.CA:80/R/?func=dbin-jump-full&object_id=86867.

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State-resolved pump/probe measurements with femtosecond temporal resolution were made to examine the size dependent charge carrier dynamics of strongly confined CdSe quantum dots. Following optical excitation, relaxation in the conduction band is shown to be consistent with the expectations of an Auger mediated process. In the valence band, the presence of a previously unobserved relaxation mechanism is detected. This mechanism is associated with non-adiabatic interactions with the surface ligands. The quantitative nature of these measurements, resulting from the explicit investigation of state-to-state transition rates, allowed for the development of a unified picture of exciton relaxation in these materials. Here the total transition rate associated with the charge carriers is composed of a manifold of different contributions, each with a distinct size dependence.
These state-resolve methods were further applied to investigate the development of optical gain in CdSe quantum dots. It was observed that the capacity of these systems to achieve the regime of optical gain has a pronounced dependence on the initially prescribed excitonic state. In general, as the energy of the initial state was increased it was progressively more difficult to achieve optical gain due to the impeding influence of state dependent multiexcitonic interactions. This explains the inability of prior research which used fixed wavelength excitation sources to demonstrate optical gain in small particles. By maintaining the identity for the pumped state in different particle sizes, the long standing prediction that quantum dots would be a universal gain medium was recovered. In addition, evidence for the capacity of specific higher order multiexcitonic interactions to manipulate the resulting optical gain spectrum was provided.
Des mesures pompe/sonde résolues en états quantiques de résolutions temporelles de l'ordre du femtoseconde ont été effectuées pour examiner la dynamique, dépendante de la taille, des transporteurs de charges de points quantiques de CdSe fortement confinés. Après l'excitation optique, la relaxation de la bande de conduction s'effectue par le mécanisme Auger, tel que prédit, alors que dans la bande de valence la présence d'un mécanisme de relaxation précédemment inobservé est détectée. Ce mécanisme est associé aux interactions non-adiabatiques avec les ligands de surface. La nature quantitative de ces mesures, résultant d'une recherche explicite sur les taux de transition d'état-à-état, a permis de développer un portrait d'ensemble de la relaxation d'exciton pour ces matériaux. Dans ce système, le taux de transition associé aux porteurs de charge se compose de différentes contributions, chacune ayant une dépendance de taille distincte.
Ces méthodes résolues en états quantiques ont été également appliquées à l'étude du développement du gain optique dans les points quantiques de CdSe. Il a été observé que la capacité de ces systèmes à atteindre le régime du gain optique dépend fortement de l'état excitonique initial. Au fur et à mesure que l'énergie de l'état fondamental fût augmentée, il fùt progressivement plus difficile d'obtenir un gain optique à cause de l'influence des interactions multiexcitoniques, dépendantes des états. Ceci explique donc l'incapacité des études antérieures, ayant utilisées des sources fixes d'excitation de longueur d'onde, à démontrer le gain optique des petites particules. La prévision émise antérieurement selon laquelle les points quantiques seraient un médium de gain universel a été confirmée en conservant l'identité pour l'état pompé dans des tailles de particules différentes. La capacité des interactions multiexcitoniques d'ordres spécifiques supérieures à manoeuvrer le gain optique résultant a aussi été prouvée.

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35

Piiroinen, Petri. "Recurrent dynamics of nonsmooth systems with application to human gait". Doctoral thesis, KTH, Mechanics, 2002. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-3430.

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36

Dixon, Philippe. "Gait dynamics on a cross-slope walking surface". Thesis, McGill University, 2008. http://digitool.Library.McGill.CA:80/R/?func=dbin-jump-full&object_id=112616.

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Though the biomechanics of level walking have been studied extensively, the adaptations required for cross-slope locomotion are still largely unknown despite being a common terrain characteristic. The goals of this thesis were to determine (1) ground reaction forces (GRF) and moments (GRM), (2) lower-limb kinematics, and (3) lower-limb joint reaction forces (JRF) and moments (JRM) during level and cross-slope walking. Statistical analyses were made across limbs (down-slope (DS) and up-slope (US)) and across slope condition (level (0°) and cross-slope (6°)) (2X2 ANOVA). Ten healthy male volunteers performed several barefoot walking trials. The lower-limbs responded asymmetrically to the cross-slope condition by substantially changing (1) the medio-lateral GRF, (2) the sagittal and frontal plane kinematics as well as step-width, and (3) the medio-lateral JRF and frontal plane JRM. The modest cross-slope induced important asymmetrical changes in locomotor patterns and may represent a substantial physical obstacle to populations with restricted mobility.

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37

Sushko, John. "Asymmetric Passive Dynamic Walker Used to Examine Gait Rehabilitation Methods". Scholar Commons, 2011. http://scholarcommons.usf.edu/etd/3373.

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Testing gait rehabilitation devices on humans can be a difficult task, due to the effects of the neurological controls of the human body. This thesis advances the use of a passive dynamic walker (PDW) tuned to have asymmetric gait patterns similar to those with physical impairments to test rehabilitation devices. A passive dynamic walker is a multipendulum system that has a stable gait pattern when walking down a slope without any energy inputs except the forces due to gravity. A PDW model is better suited for testing rehabilitation devices because it has been shown to resemble human gait and separates the human neurological controls from the purely dynamic aspects of walking. This research uses different asymmetric gait patterns based on an asymmetric PDW to aid in the design of current and future rehabilitation methods. There are four major parts to this research: (1) the derivation of the current nine mass PDW model, (2) the effects of changing the moment of inertia and center of mass on each leg, (3) the effects of having a leg that is longer than the other and adding masses on the opposite leg to generate a symmetric gait, and (4) the design of a theoretical prosthesis that will break the assumption that the knee on the prosthetic leg should be in the same location as the intact leg. The result of changing the moment of inertia and center of mass on each leg in the nine mass model showed that it is an improvement over the previously used five mass model. This is because the five mass model forces the center of mass to change with the moment of inertia, while the nine mass model allows these to be changed independently of each other. A theoretical prosthesis has been developed in this research that is is significantly lighter while maintaining a symmetric gait. This was accomplished by moving the knee of the prosthetic limb below the location of the intact knee.

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38

Ko, Seung-uk. "Human gait analysis by gait pattern measurement and forward dynamic model combined with non linear feedback control /". Connect to this title online, 2007. http://hdl.handle.net/1957/3754.

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39

Sève, Florian. "Commande robuste pour une classe de systèmes non linéaires à paramètres variants : application aux projectiles guidés". Thesis, Université de Lorraine, 2016. http://www.theses.fr/2016LORR0281.

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Ce mémoire de thèse traite du développement des dynamiques et des lois de commande de vol d’un projectile d’artillerie gyrostabilisé guidé par une tête découplée. Un modèle non linéaire du projectile est proposé, et sert à calculer un modèle linéarisé de la dynamique de roulis du nez et un modèle q-LPV des chaînes de tangage et de lacet à paramètres fortement variants. Les incertitudes de modélisation sont prises en compte pour concevoir l’autopilote. Des propriétés importantes des projectiles gyrostabilisés, qui sont liées au couplage dynamique tangage/lacet, aux modes internes et à la stabilité, sont mises en valeur grâce au modèle q-LPV. En vue de l’utiliser pour calculer une loi de commande, la dimension de son vecteur des paramètres est réduite et la position des capteurs intégrés dans le nez est considérée. Un seul correcteur linéaire est suffisant pour la dynamique de l’angle de roulis du nez alors qu’une stratégie systématique de commande par séquencement de gains basée sur une linéarisation est élaborée séparément pour générer un correcteur séquencé des facteurs de charge de tangage et de lacet. Des structures de commande fixées d’ordre réduit sont conçues en appliquant la même approche de synthèse linéaire H∞ par façonnage de gain de boucle pour les axes de roulis et de tangage/lacet. De très bonnes propriétés de performance et de robustesse en boucle fermée, comparables à celles fournies par des correcteurs d’ordre plein, sont obtenues. Finalement, l’efficacité de l’autopilote augmenté d’une loi de guidage par navigation proportionnelle pure est vérifiée via de nombreuses simulations non linéaires de trajectoires. Ces dernières correspondent à des scénarios de vol nominaux d’interception de cibles balistiques, non balistiques immobiles, ou manœuvrantes, ainsi qu’à des scénarios considérant des perturbations sur les conditions de tir ou sur les dynamiques du projectile guidé
This thesis addresses the development of the flight dynamics and control laws for an artillery spin-stabilized projectile equipped with a decoupled guidance nose. A projectile nonlinear model is discussed, and it is used for computing a linearized model of the nose roll dynamics along with a q-LPV model of the highly parameter-varying pitch/yaw-dynamics. Modeling uncertainty is taken into account for autopilot design. Important properties specific to spin-stabilized projectiles, which are relevant to pitch/yaw-channel cross-coupling, internal modes and stability, are highlighted using the q-LPV model. In order to use the latter for calculating a control law, the dimension of its parameter vector is reduced and the position of the nose-embedded sensors is considered. A single linear controller is sufficient for the nose roll angle dynamics whereas a systematic linearization-based gain-scheduled control strategy is separately devised to provide a pitch/yaw-axis load factor gain-scheduled controller. Controllers of reduced-order fixed structures are computed by applying the same H∞ linear design loop-shaping approach for the roll and pitch/yaw-axes. Very good closed-loop performance and robustness properties, which are similar to those provided by full order controllers, are obtained. Finally, the effectiveness of the autopilot augmented by a pure proportional navigation guidance law is verified through a variety of nonlinear trajectory simulations. The latter correspond to nominal flight scenarios with ballistic, non-ballistic stationary, and maneuvering interception points, and to scenarios with perturbed launch conditions or guided projectile dynamics

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40

Kumar, Tushar. "Characterizing and controlling program behavior using execution-time variance". Diss., Georgia Institute of Technology, 2016. http://hdl.handle.net/1853/55000.

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Immersive applications, such as computer gaming, computer vision and video codecs, are an important emerging class of applications with QoS requirements that are difficult to characterize and control using traditional methods. This thesis proposes new techniques reliant on execution-time variance to both characterize and control program behavior. The proposed techniques are intended to be broadly applicable to a wide variety of immersive applications and are intended to be easy for programmers to apply without needing to gain specialized expertise. First, we create new QoS controllers that programmers can easily apply to their applications to achieve desired application-speciﬁc QoS objectives on any platform or application data-set, provided the programmers verify that their applications satisfy some simple domain requirements speciﬁc to immersive applications. The controllers adjust programmer-identiﬁed knobs every application frame to effect desired values for programmer-identiﬁed QoS metrics. The control techniques are novel in that they do not require the user to provide any kind of application behavior models, and are effective for immersive applications that defy the traditional requirements for feedback controller construction. Second, we create new proﬁling techniques that provide visibility into the behavior of a large complex application, inferring behavior relationships across application components based on the execution-time variance observed at all levels of granularity of the application functionality. Additionally for immersive applications, some of the most important QoS requirements relate to managing the execution-time variance of key application components, for example, the frame-rate. The proﬁling techniques not only identify and summarize behavior directly relevant to the QoS aspects related to timing, but also indirectly reveal non-timing related properties of behavior, such as the identiﬁcation of components that are sensitive to data, or those whose behavior changes based on the call-context.

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41

Guo, Yixuan. "Hexapod Gait Planning and Obstacle Avoidance Algorithm". University of Toledo / OhioLINK, 2016. http://rave.ohiolink.edu/etdc/view?acc_num=toledo1461868607.

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42

Samson, Christine O. "The Creation and Validation of the Dynamic Injury Screening Tool for the Lower Extremity (DISTLE)". Ohio University / OhioLINK, 2014. http://rave.ohiolink.edu/etdc/view?acc_num=ohiou1396977937.

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43

Majer, Niels [Verfasser] y Eckehard [Akademischer Betreuer] Schöll. "Nonlinear Gain Dynamics of Quantum Dot Semiconductor Optical Amplifiers / Niels Majer. Betreuer: Eckehard Schöll". Berlin : Universitätsbibliothek der Technischen Universität Berlin, 2012. http://d-nb.info/102288574X/34.

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44

He, Chengming. "Robust design of high gain amplifiers using dynamical systems and bifurcation theory". [Ames, Iowa : Iowa State University], 2007.

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45

Anderson, Frank Clayton. "A dynamic optimization solution for a complete cycle of normal gait /". Digital version accessible at:, 1999. http://wwwlib.umi.com/cr/utexas/main.

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46

Quick, Tyler James. "Temporal and Spatial Variability in Base Materials Treated with Asphalt Emulsion". BYU ScholarsArchive, 2011. https://scholarsarchive.byu.edu/etd/2715.

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The first objective of this research was to investigate temporal trends in the mechanical properties of base materials stabilized with asphalt emulsion and to assess the rate at which emulsion-treated base (ETB) design properties are achieved. The second objective of this research was to identify construction and environmental factors most correlated to specific mechanical properties of ETB layers and to determine which construction factors exhibit the greatest variability. Additional statistical analysis was performed to determine if significant differences existed between different test sections on a given project. In this research, three experimental sections were established along a pavement reconstruction project near Saratoga Springs, Utah. Field tests were performed to assess the structural properties of the ETB immediately following construction and at 2, 3, 7, and 14 days; 4 months; and 1 year. Measured values were plotted against time to determine trends in ETB strength development. Several statistical analyses were then performed on the collected data. Modulus values were consistently low in all three sections during the first two weeks of testing, increased dramatically by 4 months, and then decreased considerably by 1 year. During the first two weeks following construction, the average ETB structural coefficient was 0.04. Only two of the three sections reached the design structural coefficient of 0.25, which occurred after approximately 3 months; however, the average structural coefficient measured for all three sections after 1 year of curing, which included a winter, was only 47 percent of the design strength. The results of this research show that, while pavement capacity is sufficient at 4 months, it is severely reduced during the first two weeks and at 1 year. Trafficking under these reduced capacities is not recommended. Statistical analysis showed that gradation, binder change during emulsion treatment, and moisture content have the most significant impact on ETB structural properties. Gradation and binder change during emulsion treatment also exhibited significant variability; tighter specifications on material gradations and improved uniformity in emulsion distribution should therefore be considered. Because of the negative impacts of moisture on ETB strength development, construction should not be performed in conditions of excess moisture.

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47

Janka, Adam Martin. "Methods of Diffusing Pulse Detonation Combustion". Thesis, Virginia Tech, 2014. http://hdl.handle.net/10919/49152.

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Pulse detonation combustion has been of interest for many years since it offers several advantages over standard deflagrative combustion. In theory, detonative combustion is a better use of fuel compared to deflagrative combustion since less entropy is generated during a detonation. As a result, detonation offers higher pressure and temperature gain across the wave front compared to the comparable deflagration. Since a detonation is a supersonic event which uses a shock to compress and dissociate reactants, a Pulse Detonation Combustor (PDC) is a relatively simple device that does not necessarily require a large compressor section at the inlet. Despite these benefits, using a turbine to extract work from a PDC is a problem littered with technical challenges. A PDC necessarily operates cyclically, producing highly transient pressure and temperature fields. This cyclic operation presents concerns with regards to turbine reliability and effective work extraction. The research presented here investigated the implementation of a pulse detonation diffuser, a device intended to temporally and spatially distribute the energy produced during a detonation pulse. This device would be an inert extension from a baseline PDC, manipulating the decaying detonation front while minimizing entropy production. A diffuser will seek to elongate, steady, attenuate, and maintain the quality of energy contained in the exhaust of a detonation pulse. These functions intend to reduce stresses introduced to a turbine and aid in effective work extraction. The goal of this research was to design, implement, and evaluate such a diffuser using the using conventional analysis and simulated and physical experimentation. Diffuser concepts using various wave dynamic mechanisms were generated. Analytical models were developed to estimate basic timing and wave attenuation parameters for a given design. These models served to inform the detail design process, providing an idea for geometric scale for a diffuser. Designs were simulated in ANSYS Fluent. The simulated performance of each diffuser was measured using metrics quantifying the wave attenuation, pulse elongation, pulse steadying, and entropy generation for each design. The most promising diffuser was fabricated and tested using a detonation tube. Diffuser performance was compared against analytical and computational models using dynamic pressure transducer diagnostics.
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48

Flick, Kevin Charles. "Biomechanics and dynamics of turning /". Thesis, Connect to this title online; UW restricted, 2005. http://hdl.handle.net/1773/5221.

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49

Orendurff, Michael S. "Dynamic foot and ankle characteristics in functionally relevant gait performance in those with and without a pathology". Thesis, University of Roehampton, 2012. https://pure.roehampton.ac.uk/portal/en/studentthesis/dynamic-foot-and-ankle-characteristics-in-functionally-relevant-gait-performance-in-those-with-and-without-a-pathology(abd2dc9a-26a9-47fd-afcc-edee49360c64).html.

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The human ankle joint is hypothesized to be a primary controller of support, propulsion and steering during locomotion. A series of experiments were initiated to understand ankle plantarflexor muscle kinematics and kinetics in normal and pathological gait, and to define the specific locomotor demands of community ambulation. Additional experiments were then conducted to quantify the effects of walking speed on plantar pressures and centre of mass motion, to illuminate the role of the ankle in acceleration and deceleration during walking, and to examine how humans alter their kinematics and kinetics to turn. The results of these experiments provide support for the hypothesis that the ankle joint is important in a wide range of locomotor movements beyond walking straight ahead at constant speed. The ankle appears instrumental in adapting to different walking speeds, altering both the pressures on specific regions the plantar surface and the motion of the centre of mass across a range of speeds. The ankle also has subtle kinetic changes that appear to modulate acceleration and deceleration during single limb stance. For turning, the ankle plays a role during slowing into the turn and accelerating after the turn, but mediolateral shears appear to alter the trajectory of the body to negotiate a corner and the external hip rotators appear to rotate the trunk toward the new direction of travel. This work extends our understanding of the ankle in functionally relevant gait activities beyond simple straight-ahead walking at constant speed. The published papers included in this supporting statement have been cited by 180 different subsequent peerreviewed publications, suggesting that this work has had some impact on the field.

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50

Slezák, Jakub. "Analogový vstupní díl pro softwarový přijímač". Master's thesis, Vysoké učení technické v Brně. Fakulta elektrotechniky a komunikačních technologií, 2012. http://www.nusl.cz/ntk/nusl-219843.

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This thesis deals with a theoretical analysis of the basic parameters of receivers, input circuit architecture and signal digitization. According to the specified assignment it is outlined block scheme of front end for software receiver with specified components and the total bilance is calculated. Individual parts of the system are designed and realized. This is a set of four input filters for bandwidths: short waves up to 30 MHz, 87,5-108 MHz, 144-148 MHz and 174-230 MHz. The main point of design is a circuit containing a low-noise amplifiers, switches, and two amplifiers with adjustable amplification. Mainly are used integrated circuits from Analog Devices corporation. To control the various switches and adjustable amplifiers was designed a separate panel, which is connected to the main circuit via a cable. In the last phase was the whole system and its components subjected to measurements. Thanks to a number of mounted SMA connectors it is possible to measure different parts of the system and we are able to modify it partially.

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Tesis sobre el tema "Dynamic gain"

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