Dissertations / Theses on the topic 'Oscillation period'

This diploma thesis is concerned with selecting the appropriate method for determining the moment of inertia to the vertical, lateral and longitudinal axis through the centre of gravity of the vehicle. Using the special mechanical device, constructed on IAE was carried out repeated measurements of known mass properties in each axis. With the aid of obtained data was calculated measurement error. To compare the resulting values was created MBS model.

This diploma thesis deals with measurement of vehicle centre of gravity height position. In the first part is created summary of methods used for measuring centre of gravity position and moment of inertia of the vehicle. In the other parts are designed and analyzed two dynamics method of measuring centre of gravity height position. This thesis presents analysis of the errors of the proposed methods, results of measurements and design of the construct adjustments device for measuring of the moments of inertia enabling its used for measuring centre of gravity height position. Some components are through analyse of tension.

This master's thesis deals with problems connected with measuring vehicle centre of gravity height. The research part summarizes generally known methods of measuring vehicle centre of gravity and moments of inertia. Essential part of this thesis is the design of a device for measuring the centre of gravity height of a road vehicle on a principle of measuring a period of oscillation. The height position of the platform of the device is adjustable through hydraulic cylinders. A stress-strain analysis of the design was executed through a combination of analytical methods and a finite element method. The process of measurement was described and an equation for determination of centre of gravity height was deduced. Error of measurement was estimated based on the knowledge of partial errors of measured values.

This diploma thesis deals with the measurement of wind oscillation waves on reservoirs, especially with regard to the determination of wave properties with a focus on the spectral density. The thesis presents the basics of the theory of creation and propagation of wind oscillation waves, the recherche of measuring devices and a description of the pilot measurement with the processing of measured data in the MATLAB environment using the software tool WAFO. Attached to the CD are sample scripts for data processing from the resistance sensor.

This thesis is concerned with the study of near-planetary rotation period oscillations in Saturn’s magnetic field. Similar oscillations are present in a variety of other magnetospheric phenomena, most notably kilometre-wavelength radio emissions, and together they have a substantial influence throughout the Saturnian plasma environment. However, their origin remains poorly understood, despite more than a decade of study. Surprising new discoveries have been made regarding the seasonality of these oscillatory phenomena, and their intrinsic connection to the high-latitude upper atmosphere and ionosphere of the planet, though a complete theory of their origin remains to be developed. In this thesis, three detailed studies of this phenomenon are presented, each of which uses magnetic field data recently obtained by the Cassini spacecraft. The first consists of an extensive survey of near-equatorial field data during southern summer, from which the structure of the rotating oscillations is determined and the electrical currents flowing through the equatorial plane are calculated. The second study is prompted by the recent discovery of a north-south asymmetry in the period of related radio emissions, and consists of a survey of high-latitude magnetic field data in which evidence for a corresponding asymmetry in the magnetic field rotation period is found. Finally, the third study concerns the presence of long-termdrifts between the phase of the magnetic field oscillation and the Saturn kilometric radiation (SKR) modulation, which, through construction of a simple theoretical model, is shown to arise as a consequence of ‘rotational’ modulations in the SKR rather than the hitherto assumed ‘strobe-like’ modulations. These three studies substantially further our understanding of these phenomena, and in the case of the detection of a rotational modulation in the SKR overturn three decades of previous thought. Consequently, the results presented here elucidate characteristics of these phenomena that any theoretical understanding of their origin must serve to explain, and will therefore be of central importance in further development of this topic in the future. Before presenting these three studies, an introduction to the topics of space plasma physics and planetary magnetospheres is presented in Chapter 1. This is followed in Chapter 2 with a discussion of Saturn’s magnetosphere, and the topic of near-planetary period oscillations, and in Chapter 3 by descriptions of the instruments with which data used in this thesis have been obtained.

This diploma thesis deals the with measurment of the centre of gravity height position of a road vehicle and its issues. The introduction of this thesis focuses on the determining of the position of the center of gravity and the moment of inertia of a road vehicle. The next part is about creationing of a construction plan and its verification. The thesis contains a sensitivity analysis of this device including its results. The end of the thesis informs about the executed measurment in a laboratory and about recommendations for next measurments.

La dynamique d'un laser a fibre dopee er#3#+ a ete analysee aussi bien en regime de pompage continu qu'en regime de pompage module. En pompage continu, lorsque l'on augmente la puissance de pompe, le laser atteint un second seuil et une bifurcation de hopf apparait menant le laser d'un regime de fonctionnement continu a un regime de fonctionnement pulse. Une etude de l'influence des parametres aussi bien intrinseques (dopage, longueur,. . . ) que extrinseques (pompage, cavite,. . . ) nous a permis de determiner dans un espace de parametres propres au laser la frontiere entre les differents regimes de fonctionnement. Nous avons aussi pu observer, aussi bien en regime de fonctionnement continu qu'en regime de fonctionnement pulse, que le comportement transitoire de l'intensite totale du laser est en fait la somme des comportements transitoires de deux etats orthogonaux de polarisation. En regime transitoire (reponse a un pompage en echelon) le laser a fibre presente des oscillations de relaxation. C'est en modulant la puissance de pompe de maniere sinusoidale au voisinage de la frequence de relaxation que nous avons pu observer dans le comportement dynamique du laser a fibre une cascade de doublement de periodes conduisant a un fonctionnement chaotique. Nous avons developpe un modele semi-classique decrivant de la dynamique du laser a fibre dopee. Cette dynamique est parfaitement decrite par un modele de deux lasers couples pompes de maniere coherente. La transition entre le regime continu et le regime pulse est bien decrite ainsi que les deux etats propres de polarisation et le comportement chaotique

In this thesis we show that Saturn’s magnetopause and bow shock oscillate with a period near that of planetary rotation that we term the ‘magnetospheric period’. In our first study, using two Cassini orbits as exemplars, we demonstrate that Saturn’s magnetopause oscillates at the magnetospheric period in response to changes in the magnetospheric pressure. The change in internal pressure required to produce such oscillations, which typically correspond to a ~10% change in the boundary radius, is estimated to be ~30-40% of the unperturbed background pressure. In our second study we develop a simple theoretical model of motion through an oscillating planar boundary that is equally applicable to the magnetopause and the bow shock. In our third study we use data from ~40 Cassini orbits to conduct a first systematic investigation of the magnetospheric period magnetopause oscillations. We show that boundary oscillation events are highly organized by the phase of the magnetic oscillations in the ‘core’ region of the magnetosphere. When radial propagation is accounted for, the phase of maximum outward boundary displacement is found to be directly related to the phase of the density maximum in the Enceladus torus. The boundary oscillation amplitude is estimated to be ~1.2 Saturn radii, but is occasionally as great as ~4-5 Saturn radii. In our fourth study we use data from 35 Cassini orbits that crossed both the magnetopause and the bow shock to provide first evidence for magnetospheric period bow shock oscillations. We find that the oscillations are significantly organized by the phase of the ‘core’ magnetosphere magnetic oscillations, though the degree of organization is less than for the magnetopause. The bow shock and magnetopause are found to oscillate approximately in phase within a phase uncertainty of about ± 25° and to have similar oscillation amplitudes.

Meteor radar observations of mesosphere/lower thermosphere (MLT) daily temperatures have been performed at Collm, Germany since August 2004. The data have been analyzed with respect to long-period oscillations at time scales of 2–30 days. The results reveal that oscillations with periods of up to 6 days are more frequently observed during summer, while those with longer periods have larger amplitudes during winter. The oscillations may be considered as the signature of planetary waves. The results are compared with analyses from radar wind measurements. Moreover, the temperature oscillations show considerable year-to-year variability. In particular, amplitudes of the quasi 5-day oscillation have increased during the last decade, and the quasi 10-day oscillations are larger if the equatorial stratospheric winds are eastward.

Daily analyses of the zonal and meridional prevailing wind at the mesopause ( - 95 km height) are investigated with respect to planetary wave scale oscillations with periods ranging between 2 and 18 days. A mean climatology of the years 1983 - 1994 is presented. Time series of planetary wave activity show a significant increase during this period, which is in accordance with results from literature
Tägliche Analysen des zonalen und meridionalen Grundwindes in der Mesopausenregion (- 95 km Höhe) werden hinsichtlich planetarer Wellenaktivität im Periodenbereich von 2 bis 18 Tagen untersucht. Es wird eine mittlere Klimatologie der Jahre 1983 - 1994 dargestellt. In diesem Zeitraum ist eine signifikante Zunahme der Wellenaktivität zu verzeichnen, die in Übereinstimmung mit Literaturangaben steht

Daily analyses of the zonal and meridional prevailing wind at the mesopause ( - 95 km height) are investigated with respect to planetary wave scale oscillations with periods ranging between 2 and 18 days. A mean climatology of the years 1983 - 1994 is presented. Time series of planetary wave activity show a significant increase during this period, which is in accordance with results from literature.
Tägliche Analysen des zonalen und meridionalen Grundwindes in der Mesopausenregion (- 95 km Höhe) werden hinsichtlich planetarer Wellenaktivität im Periodenbereich von 2 bis 18 Tagen untersucht. Es wird eine mittlere Klimatologie der Jahre 1983 - 1994 dargestellt. In diesem Zeitraum ist eine signifikante Zunahme der Wellenaktivität zu verzeichnen, die in Übereinstimmung mit Literaturangaben steht.

Using measurements, derived from a meteor radar in Collm (51.3°N, 13°E), the mesopause region is analyzed with respect to the temperature distribution at an altitude of 90 km over a period of 10 years. The analyzed period lasts from 2005 till 2013. Based on these measurements, the typical temperature seasonal cycle of the mesopause region can be observed. The temperature reaches its minimum of about 130 K in summer and its maximum of about 220 K in winter. At this altitude, also strong day-today- fluctuations of up to 35 K exist, which are probably partly induced by planetary waves. Shorter-period oscillations with a period between 2 and 6 days have maximum amplitudes during summer, while longer-period oscillations with a period between 7 and 20 days maximize during winter. During the measurement period the amplitudes of oscillations with periods between 4 and 6 days, which may be attributed to the quasi-5-day-wave, increase with time.
Auf der Grundlage von Messungen eines Meteorradars in Collm (51.3°N, 13°E), die in einer Höhe von 90 km erfolgten, was in etwa der Mesopause entspricht, wird die Temperatur hinsichtlich ihres Jahresganges und insbesondere ihrer Variationen in einem Messzeitraum von 10 Jahren analysiert. Der analysierte Zeitraum erstreckt sich von 2005 bis 2013. Anhand der Daten kann man den typischen Jahresgang der Temperatur in der Mesopausenregion erkennen. Die Temperatur erreicht im Sommer das Minimum bei etwa 130 K und im Winter das Maximum bei etwa 220 K. Zudem treten starke Tag-zu-Tag-Fluktuationen auf, die im Maximum 35 K betragen. Diese werden vermutlich durch planetare Wellenaktivität der Atmosphäre hervorgerufen. Hierbei spielen im Sommer die kurzwelligen und im Winter die langwelligen Oszillationen, letztere mit Perioden größer 7 Tage, die wesentliche Rolle. Ferner sind innerhalb des Messzeitraums zunehmende Amplituden von Oszillationen mit Perioden zwischen 4 und 6 Tagen (quasi 5-Tage-Welle) zu erkennen.

A study on phase synchronization in large populations of nonlinear dynamical systems is presented in this thesis. Using the well-known Rossler system as a prototypical model, phase synchronization in one oscillator with periodic external forcing and in two-coupled nonidentical oscillators was explored at first. The study was further extended to consider three-dimensional lattices and globally coupled populations of nonidentical oscillators, in which the mathematical formulation that represents phase synchronization in the generalized N-coupled Rossler system was derived and several computer programs that perform numerical simulations were developed. The results show the effects of coupling dimension, coupling strength, population size, and system parameter on phase synchronization of the various Rossler systems, which may be applicable to studying phase synchronization in other nonlinear dynamical systems as well.
M.S.
Department of Mathematics
Arts and Sciences
Mathematics

Oscillations are present at many different levels of biological organization. The cell cycle that directs the division of individual cells, the regular depolarization of neurons in the sinu-atrial node which underlies the regular beating of the heart, the circadian rhythms that govern the daily activity cycles of virtually all organisms, and the clocks that make entire populations of fireflies flash on and off in unison feature as prominent examples of biological clocks. During development, biological clocks regulate the patterning of growing tissues, as is the case in vertebrate somitogenesis, and potentially also in vertebrate limb outgrowth and axial segmentation of invertebrate embryos. During vertebrate segmentation, the embryonic axis is subdivided along its anterior-posterior axis into epithelial spheres of cells called somites. This rhythmic process is thought to be driven by a multicellular oscillatory gene network, the so-called segmentation clock. Oscillations of hairy and enhancer of split gene products have been proposed to constitute the core clockwork in individual cells, and these oscillators are coupled to each other by Delta-Notch intercellular signaling. The interaction of the segmentation clock with a posteriorly-moving arrest wavefront then translates the temporal information encoded by the clock into a spatial pattern of segments. In the framework of this Clock and Wavefront model, segment length is determined by both clock period and arrest wavefront velocity. How the period of the segmentation clock is regulated is presently unknown, and understanding the mechanism of period setting might yield insight into the nature and function of the segmentation clock. In this study, two different but complementary approaches were pursued to investigate how period is regulated in the zebrafish segmentation clock. First, it has been reported that zebrafish mind bomb (mib) mutant embryos form somites more slowly than their wt siblings, suggesting that Mib might be implicated in period setting. Mib is an E3 ubiquitin ligase required for ubiquitination and endocytosis of the Notch ligand Delta, and Notch signaling is impaired in mutants with defective Mib. It has been suggested that the mechanistic basis for the requirement of Delta endocytosis in Notch signaling is a need for Delta to enter a particular endocytic compartment, potentially a recycling endosome, in a ubiquitin-dependent manner, where its signaling ability might be established or amplified by an as yet unknown posttranslational modification. In the present study, Delta trafficking through the endocytic pathway was analyzed in the PSM of wt and mib embryos through colocalization studies with endocytic markers. The rationale of this approach was that if Delta gained access to a particular endocytic compartment through Mib-dependent endocytosis, the presence of Delta in this compartment would be expected to be reduced in mutants with defective Mib, thereby revealing the compartment’s identity. However, no qualitative changes in colocalization with different endocytic markers could be detected in mib mutants, and the methods available did not allow for quantification of colocalization in wt or mutant backgrounds. However, Delta colocalized with 13 markers of recycling endosomes, consistent with the hypothesis that these are functionally important in Notch signaling. More refined techniques will be necessary for a quantitative analysis of normal as compared to impaired Delta trafficking. A genetic approach to period regulation proved to be successful for the Drosophila circadian clock, where the identification of period mutants advanced the understanding of the clock’s genetic circuitry. This motivated a screen for period mutants of the segmentation clock, which was carried out by measuring somitogenesis period, segment length and arrest wavefront velocity in a pool of candidate mutants. A subset of Delta-Notch mutants, and embryos treated with a small-molecule inhibitor that impairs Notch signaling, displayed correlated increases in somitogenesis period and segment length, while there was no detectable change in arrest wavefront velocity. Combined, these findings suggested that segmentation clock period is increased in experimental conditions with impaired Delta-Notch signaling. Using a theoretical description of the segmentation clock as an array of coupled phase oscillators, the delay in the coupling and the autonomous frequency of individual cells were estimated from the direction and magnitude of the period changes. The mutants presented here are the first candidates for segmentation clock period mutants in any vertebrate. The nature of the molecular lesions in these mutants, all of which affect genes implicated in intercellular Delta-Notch signaling, suggests that communication between oscillating PSM cells is a key factor responsible for setting the period of the segmentation clock.

High-pass filtering that is one of the most efficient methods in removing long-period noise of accelerograms is investigated for its effect on nonlinear oscillator deformation response. Within this context, uncertainty in filter cut-off periods that would significantly modify the low-frequency content of accelerograms come into prominence for obtaining reliable long-period displacement response. Analog and digital ground-motion records from recently compiled Turkish strong-motion database are used and these records are high-pass filtered with a consistent methodology by randomly generated filter cut-offs that represent different filter cut-off decisions of the analysts. The uncertainty in inelastic spectral and residual displacements (SDIE and SDR, respectively) due to variations in filter cut-offs is examined to derive the usable period ranges where the effect of high-pass filtering is tolerable. Non-degrading, stiffness degrading and stiffness and strength degrading oscillator behavior are considered in these analyses. The level of nonlinear behavior in single degree of freedom (SDOF) response is described by varying the yield strength (R, normalized yield strength) and displacement ductility (µ
) levels. The usable period ranges that depend on magnitude, recording quality, level of inelasticity and level of degradation are determined for SDIE through robust probabilistic methodologies.

Dans ce travail, on étudier, au voisinage d'un point d'équilibre, l'existence et l'unicité et la dépendance régulière des solutions presque-périodique (p.p.), présqu'automorphe (p.a.), asymptotiquement p.p., asymptotiquement p.a., pseudo p.p., pseudo p.a., pseudo p.p. avec poids, pseudo p.a. avec poids de la famille d'équations de Liénard forcée suivantes x''(t) + f(x(t), p). x'(t) + g(x(t), p) = ep(t), (1) où le terme ep est de la même nature que la solution, et p est un paramètre dans un espace de Banach. On utilise le théorème des fonctions implicites au voisinage de l'équilibre. On étudier aussi deux cas particuliers de la famille (1) qui sont x''(t) + f1(x(t)). x'(t) + g1(x(t))= e(t), x''(t) + f2(x(t), q). x'(t) + g2(x(t), q) = e(t). On établit aussi un nouveau résultat sur la dépendance différentielle des solutions S-asymptotiquement presque-périodique du problème de Cauchy x'(t)=A(t) x(t)+f(t, x(t),u(t) ) x(0) = ζ , par rapport à la condition initial et le contrôle u. On applique cet résultat sur une équation parabolique avec coefficients périodique par rapport au temps.

In this work present the broad-band noise structure in the 2-60 keV data of Cataclysmic Variables (CVs) with Anomalous X-Ray Pulsars (AXPs) and Soft Gamma Repeaters (SGRs). We analyzed Rossi X-ray Timing Explorer (RXTE) PCA data and derived time series from 27 CVs, 4 AXPs and 1 SGR using the RXTE archive. In general, CVs of different types all show broad band noise which can be fitted with power laws, using exponentional cut-offs, and Lorentzians in a similar way to power spectral (noise) characteristics of X-ray Binaries (XRBs). In general terms the power spectra show a power law index of (-)1.2-2. A rather large scale flattening of the power spectra exits in nonmagnetic systems in the low to very low frequency range. We observe that in low and high states/outbursts the noise in the high frequency range and low frequency range is changed. CVs show considerably low frequency noise. In addition, we recovered several possible QPOs in the X-ray wavelengths from CVs mainly from Intermediate Polar systems. AXP and SGR sources which are thought to be powered by either magnetic decay or accretion show band limited noise in their low frequencies. We also correlated their equal time interval noise characteristic with their burst states and discovered that in the two AXPs (1E 2259+586, 1E 1048.1-5937) noise correlates with their bursts.

Human activity and other events can cause environmental changes to the habitat of organisms. The environmental changes effect the vital rates for a population. In order to predict the impact of these environmental changes on populations, we use two different models for population dynamics. One simpler linear model that ignores environmental competition between individuals and another model that does not. Our population models take into consideration the age distribution of the population and thus takes into consideration the impact of demographics. This thesis generalize two theorems, one for each model, developed by Sonja Radosavljevic regarding long term upper and lower bounds of a population with periodic birth rate ; see [6] and [5]. The generalisation consist in including the case where the periodic part of the birth rate can be expressed with a finite Fourier series and also infinite Fourier series under some constraints. The old theorems only considers the case when the periodic part of the birth rate can be expressed with one cosine term. From the theorems we discover a connection between the frequency of oscillation and the effect on population growth. From this derived connection we conclude that periodical changing environments can have both positive and negative effects on the population.

Cette thèse vise à étudier expérimentalement, analytiquement et numériquement, les conséquences de variations et d'oscillations hydrodynamiques à forte variabilité temporelle en milieux poreux partiellement saturés. Les problèmes que nous étudions comportent des surfaces libres tant à l'extérieur qu'à l'intérieur des milieux poreux, celles-ci étant définies comme des isosurfaces de pression d'eau égale à la pression atmosphérique (Pwater = Patm). Les différentes études expérimentales réalisées en laboratoire sont, respectivement : une expérience d'imbibition dans une boite à sable avec effets capillaires importants; la transmission d'oscillations de la surface libre à travers un massif sableux intercalaire dans un petit canal à houle (IMFT, Toulouse); l'étude de la dynamique et de la propagation des oscillations des niveaux d'eau dans un grand canal à houle (HYDRALAB, Barcelone), partiellement recouvert d'un fond sableux incliné, avec mesures de niveaux d'eau en pleine eau et sous le sable, et mesures du fond sableux (érosion/dépôts). Pour les études théoriques, nous avons développés des solutions analytiques linéarisées. Un exemple de problème traité analytiquement est: l'équation linéarisée de Dupuit-Boussinesq (D-B) transitoire à surface libre, en hypothèse d'écoulements plans et vidange/remplissage instantané : oscillations forcées, transmission et dissipation d'ondes à travers une boite à sable rectangulaire. Nous avons aussi développé une solution de l'équation faiblement non linéaire de Dupuit- Boussinesq (D-B) pour étudier le problème d'imbibition avec variation abrupte du niveau d'eau amont (suivi temporel du front de saturation). Nous avons pu étudier les différents types de problèmes transitoires liés aux expériences citées plus haut par simulation numérique. En particulier, nous avons simulé des écoulements partiellement saturés et insaturés, en coupe verticale, à l'aide d'un code de calcul (BIGFLOW 3D) qui résoud l'équation de Richards généralisée en régime transitoire. Nous avons ainsi étudié numériquement en régime non saturé, l'expérience d'imbibition dans un sable initialement sec à frontières verticales (IMFT sandbox), puis l'expérience de propagation d'ondes dans le grand canal à houle de Barcelone (laboratoire HYDRALAB) comportant une plage de sable inclinée, avec un couplage complètement intégré entre les zones micro-poreuse (sable) et “macro-poreuse” (pleine eau). Pour analyser les résultats de cette dernière expérience et les comparer aux simulations, nous avons utilisé plusieurs méthodes de traitement et d'analyse des signaux : analyse de Fourier (spectres de fréquences) ; ondelettes discrètes multi-résolution (Daubechies) ; analyses corrélatoires simple et croisée. Ces méthodes sont combinées avec des méthodes de préfiltrage pour estimer dérives et résidus (moyennes mobiles ; ondelettes multi-résolution). Cette analyse des signaux a permis de comprendre et quantifier la propagation à travers une plage de sable. Au total, les différentes approches de modélisation mis en oeuvre, associé à des procédures de calage en situation de couplage transitoire non linéaire ont permis de reproduire globalement les phénomènes de propagation de teneur en eau et de niveau d'eau dans les différentes configurations étudiées
This thesis aims at investigating experimentally, analytically and numerically, the consequences of hydrodynamic variations and oscillations with high temporal variability in partially saturated porous media. The problems investigated in this work involve “free surfaces” both outside and inside the porous media, the free surface being defined as the “atmospheric” water pressure isosurface (Pwater = Patm). The laboratory experiments studied in this work are, respectively: Lateral imbibition in a dry sand box with significant capillary effects; Transmission of oscillations of the free surface through a vertical sand box placed in a small wave canal (IMFT, Toulouse); Dynamics of free surface oscillations and wave propagation in a large wave canal (HYDRALAB, Barcelona), partially covered with sand, with measurements of both open water and groundwater levels, and of sand topography (erosion / deposition). For theoretical studies, we have developed linearized analytical solutions. Here is a sample problem that was treated analytically in this work: The linearized equation of Dupuit-Boussinesq (DB) for transient free surface flow, assuming horizontal flow and instantaneous wetting/drainage of the unsaturated zone: forced oscillations, wave transmission and dissipation through a rectangular sandbox. We also developed a weakly nonlinear solution of the Dupuit-Boussinesq equation to study the sudden imbibition (temporal monitoring of the wetting front). We have studied the different types of transient flow problems related to the experiments cited above by numerical simulation. In particular, we have simulated unsaturated or partially saturated transient flows in vertical cross-section, using a computer code (BIGFLOW 3D) which solves a generalized version of Richards’ equation. Thus, using the Richards / BIGFLOW 3D model, we have studied numerically the experiment of unsaturated imbibition in a dry sand (IMFT sandbox), and then, with the same model, we have also studied the partially saturated wave propagation experiment in the large Barcelona wave canal (HYDRALAB laboratory), focusing on the sloping sandy beach, with coupling between the micro-porous zone (sand) and the “macro-porous” zone (open water). To interpret the results of the latter experiment and compare them to simulations, we use several methods of signal analyzis and signal processing, such as: Fourier analysis, discrete multi-resolution wavelets (Daubechies), auto and cross-correlation functions. These methods are combined with pre-filtering methods to estimate trends and residuals (moving averages; discrete wavelet analyses). This signal analyzis has allowed us to interpret and quantify water propagation phenomena through a sandy beach. To sum up, different modeling approaches, combined with model calibration procedures, were applied to transient nonlinear coupled flow problems. These approaches have allowed us to reproduce globally the water content distributions and water level propagation in the different configurations studied in this work

We prove the existence and linear stability of quasi-periodic breather solutions in a 1d Hamiltonian lattice of identical, weakly-coupled, anharmonic oscillators with general on-site potentials and under the effect of long-ranged interaction, via de KAM technique. We prove the persistence of finite-dimensional tori which correspond in the uncoupled limit to N arbitrary lattice sites initially excited. The frequencies of the invariant tori of the perturbed system are only slightly deformed from the frequencies of the unperturbed tori.

L'objet de cette etude est la determination qualitative et quantitative des regimes oscillatoires et vibro-rotatifs d'un systeme dynamique conservatif ou faiblement amorti, modelises par l'equation du pendule excite periodiquement. L'analyse qualitative est basee essentiellement sur l'etablissement de la distribution des singularites dans le plan de phase de la recurrence associee, pour les regimes oscillatoires, et sur un cylindre de phase particulier pour les regimes vibro-rotatifs. La connaissance des proprietes quantitatives a permis de construire les expressions analytiques approchees de plusieurs solutions stationnaires oscillatoires et vibrorotatives ainsi que leurs solutions voisines. Ces solutions permettent de determiner les regimes importants pour les applications techniques

In this thesis, RXTE observations of 4U 1907+09 are presented. Timing analysis of these data sets have yielded quasi periodic oscillations (QPOs) at orbital phases corresponding to the two flares in every orbital period. Known continuous spin down trend and QPO behaviour at the flares strongly suggest that a transient accretion disk occurs at the flares. Our findings strongly suggested that neutron star passes through the equatorial wind of Be companion star. During these passages a transient disk forms around Be neutron star.

Any periodic signal can be decomposed into a sum of oscillating functions. Traditionally, cosine and sine segments have been used to represent a single period of the periodic signal (Fourier Series). In more general cases, each of these functions can be represented by a set of spectral parameters such as its amplitude, frequency, phase, and the variability of its instantaneous spectral components. The accuracy of these parameters depends on several processing variables such as resolution, noise level, and bias of the algorithm used. This thesis presents some background of existing frequency estimation techniques and proposes a new technique for estimating the instantaneous frequency of signals using short sinusoid-like basis functions. Furthermore, it also shows that the proposed algorithm can be implemented in a popular embedded DSPmicroprocessor for practical use. This algorithm can also be implemented using more complex features on more resourceful processing processors in order to improve estimation accuracy

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O presente trabalho apresenta a modelagem matemática de um sistema vibracional com excitação harmônica da base. Esse tipo de sistema tem sido estudado por vários pesquisadores que exploraram muitos aspectos da dinâmica global. No entanto, na grande parte dos sistemas estudados, o sistema era modelado para uma característica de vibroimpacto. No sistema aqui estudado, os impactos são substituídos por outro conjunto visco-elástico e os instantes de transição são considerados como condição de periodicidade. As condições de periodicidade são aplicadas sobre o estado nos instantes de transição a fim de obter um mapa da próxima transição baseada no estado da anterior. Este mapa não-linear é aplicado para obter as condições de existência dos movimentos periódicos com padrões específicos. Assim, aplicando as condições de existência, a estabilidade do movimento pode ser realizada por meio da análise dos autovalores do mapa linearizado, tendo em conta estas restrições
This work presents the mathematical modeling of a vibrational system with the harmonically excited base. The system has been investigated by several researchers exploring many aspects of the global dynamics. However, in most of the systems studied, the systems were modeled for a vibro-impact feature. In this system, the impacts are replaced by another visco-elastic set and the moment of transition is considered as a condition of periodicity. Periodicity conditions are applied on the state at the moment of transition in order to obtain a map of the next transition based on the state of the previous one. This nonlinear map is used to obtain the conditions of existence of periodic motions with specific patterns. Applying the existence conditions, the stability of the motion can be achieved by analyzing the eigenvalues of the linearized map while taking these conditions into account

L'étude cinétique d'une réaction catalytique permet une meilleure compréhension du mécanisme réactionnel et du fonctionnement du catalyseur. Elle est nécessaire pour le dimensionnement des réacteurs et des procédés. Les modèles micro-cinétiques sont constitués d'une séquence d'étapes élémentaires sans hypothèses sur les étapes cinétiquement déterminantes. Ces modèles sont applicables sur des plages de conditions opératoires plus larges que celles des modèles plus classiques de type Langmuir-Hinshelwood (LH) ou d'Hougen-Watson. Lorsqu'ils sont implémentés dans un modèle de réacteur, ils permettent d'obtenir une plus grande précision vis-à-vis du dimensionnement du catalyseur et du réacteur. Cependant, cette approche nécessite un nombre d'expériences plus élevé pour estimer les nombreux paramètres cinétiques qui le constituent. Ce travail de thèse porte sur le développement de modèles micro-cinétiques de systèmes catalytiques en exploitant les informations obtenues lorsque le catalyseur fonctionne en régime transitoire. En effet, l'expérimentation en régime transitoire, en comparaison avec celle classiquement réalisée en régime stationnaire, permet d'accéder à plus d'informations par une meilleure sensibilisation des réactions mises en jeu. Les études cinétiques en régime permanent sont plutôt adaptées pour des modèles cinétiques globaux qui considèrent un nombre limité d'étapes cinétiquement déterminantes (en général une seule). De ce fait, la compréhension du mécanisme réactionnel [1], la connaissance du nombre de types de sites actifs mis en jeu ou encore la détermination des vitesses de réaction des étapes élémentaires restent imprécises. Afin d'accéder aux différentes vitesses de réaction des étapes élémentaires, il est nécessaire de réaliser un grand nombre d'expériences en régime permanent, ce qui est très coûteux en temps et en argent. L'expérimentation en régime transitoire est donc une alternative qui permet d'accéder à des informations cinétiques détaillées dans un délai plus rapide. Cependant, l'interprétation des expériences est plus fastidieuse puisqu'elle nécessite le développement de modèles dynamiques de réacteur. Ces études consistent à réaliser des perturbations sous forme de pulses, d'échelons ou bien d'oscillations périodiques d'un certain nombre de paramètres d'état tels que la concentration des réactifs, la pression ou encore la température. Dans ces travaux, des oscillations périodiques de concentration sont réalisées en entrée de réacteur. Ce choix permet de réaliser des variations autour de l'état stationnaire, dans des conditions proches des celles utilisées dans l'industrie. La mise en place et la validation de cette méthodologie ont été réalisées pour un système catalytique réactionnel d'intérêt industriel : l'hydrogénation sélective de l'acétylène. Cette réaction a lieu en phase gaz au contact d'un catalyseur solide et présente l'avantage de mettre en jeu peu de composés facilement analysables. Une voie importante pour la production d'éthylène est le vapocraquage. L'éthylène produit par ce procédé contient de faibles quantités d'acétylène qu'il faut éliminer car il constitue un poison pour les procédés catalytiques en aval. Cette élimination se fait par l'hydrogénation sélective de l'acétylène, en présence d'éthylène, en employant un catalyseur à base de palladium. C'est une réaction rapide dont le mécanisme réactionnel n'est pas encore complètement connu.La cinétique transitoire permet non seulement d'étudier les réactions chimiques mais également de caractériser le transport des réactifs et des produits, de l'échelle du lit catalytique à l'échelle des pores du catalyseur. Un modèle de réacteur incluant un modèle cinétique a été développé pour expliquer les données expérimentales obtenues sur un réacteur pilote. Des manipulations en régime transitoires et une modélisation dynamique de l'unité pilote incluant un modèle micro-cinétique sont réalisées [etc...]
Kinetic experiments performed under stationary conditions mainly give information on the rate determining step. Numerous experiments must be done to estimate a limited number of parameters. Unsteady-state experiments, on the other hand, give more detailed information about the kinetics of the different elementary steps with a small number of experiments. In order to work under dynamic conditions, a perturbation of a process variable (concentration, pressure, temperature, etc.) is introduced at the reactor entrance (pulse, step, oscillation ...). This study explores periodic sinusoidal variations of the flow to obtain kinetics for heterogeneous catalytic processes. The kinetic information is contained in the phase lag and the gain change of the oscillations. The oscillations can be kept small and can be performed around steady-state operation, thus studying the kinetics under relevant conditions. First a model able to directly estimate the gain and phase lag has been created. Secondly, simple cases of adsorption have been performed in order to validate the model and to test the experimental set up. To finish, the approach has been applied to the selective hydrogenation of acetylene. Kinetic modeling was carried out in both stationary and dynamic conditions in order to compared the two methodologies

In this thesis, X-ray observations of four accretion powered pulsars are presented. Using RXTE observations of 4U 1907+09, we found three new pulse periods of the source. We found that the source spun-down almost at a constant rate of $dot nu$ = (-3.54 $pm 0.02) times 10^{-14}$ Hz s$^{-1}$ for more than 15 years. Using RXTE observations, X-ray flux related spectral and timing features in 2S 1417-62 were, in general, interpreted as a sign of a disc accretion with a similar geometry with a varying mass accretion rate, whereas spectral and timing features of the low X-ray flux regions were interpreted as a sign of possible temporary accretion geometry change prior to the next periastron. Using XMM-Newton and RXTE observations of SAX J2103.5+4545, we discovered quasi periodic oscillations around 0.044 Hz (22.7 sec) while the source was spinning-up with a rate of $(7.4pm0.9)times10^{-13}$Hz s$^{-1}$. In the X-ray spectrum, we also found a soft component consistent with a blackbody emission with ${rm{kT}}sim1.9$keV. Using RXTE observations, we also studied spectral evolution of Her X-1

This thesis presents an experimental study of the superconducting proximity effect in sub-micrometer sized ferromagnetic discs. Such discs belong to a class of mesoscopic ferromagnets intermediate between microscopic magnets with dimensions below about 10nm that behave as single giant spins and macroscopic structures that are larger than approximately 1 micrometer where domains are formed to minimise stray fields. The magnetic structure of mesoscopic magnets is strongly dependent on their geometric shape, allowing for purposeful engineering of magnetic structures using modern lithographic techniques. The ground magnetic state of mesoscopic ferromagnetic discs is the magnetic vortex where unusual time-asymmetric triplet superconductivity is predicted to exist and survive up to the non-magnetic coherence length, that is orders in magnitude larger than the ferromagnetic singlet coherence length. Magnetic Force Microscopy (MFM) was used to directly study the magnetic structure of the discs. To detect the proximity effect in the vortices, Andreev interferometers were used with normal parts replaced with mesoscopic ferromagnetic discs in the magnetic vortex state. The samples were fabricated using electron-beam lithography and a modified shadow evaporation technique developed within this project, allowing the whole structure to be made with highly precise alignment, without breaking vacuum and avoiding redundant ferromagnetic elements disturbing the magnetic vortices. Observations were made of superconducting phase periodic oscillations in the conductance of the Andreev interferometers. Such oscillations provide unambiguous evidence of phase coherent electron transport through the ferromagnetic vortex. Finally, further experiments are discussed that would provide a more detailed understanding of the long range proximity effect in SFS junctions.

In this thesis, RXTE timing analysis of Galactic Microquasars GRO J1655-40 and GRS 1915+105, the Chandra and RXTE joint spectral analysis of GRS 1915+105 are presented. We have investigated quasi periodic oscillations (QPOs) in the black hole binaries GRO J1655-40 and GRS 1915+105 observed in 99 and 122 observations made by the Proportional Counter Array (PCA) on board Rossi X-Ray Timing Explorer (RXTE) in both low energy band (2-12 keV) and high energy band (13-27 keV), respectively. Four different X-ray states are seen in the combined characteristics of power spectra, light curves extracted by using All Sky Monitor (ASM) and spectra during 1996 and 2005. Timing analysis of RXTE observations of both of two black hole binaries GRO J1655-40 and GRS 1915+105 displays twin high frequency quasi periodic oscillations (QPOs) which are sometimes simultaneous in high energy band. It is also shown that the time averaged 30 ksec Chandra grating spectrum analysis and RXTE spectrum analysis of recent observation of GRS 1915+105 in the very high state are consistent with the parameters which were mentioned before. We briefly discussed our results and the models on black hole spin and mass.

Les systèmes « excitables » sont omniprésents dans la nature, le plus paradigmatique d'entre eux étant le neurone, qui répond de façon « tout ou rien » aux perturbations externes. Cette particularité étant clairement établie comme l'un des points clé pour le fonctionnement des systèmes nerveux, son analyse dans des systèmes modèles (mathématiques ou physiques) peut d'une part aider à la compréhension de la dynamique d'ensembles de neurones couplés et d'autre part ouvrir des voies pour un traitement neuromimétique de l'information. C'est dans cette logique que s'inscrit la préparation de cette thèse de doctorat. Dans ce mémoire, nous utilisons des systèmes basés sur des lasers à semiconducteur pour d'une part modéliser des systèmes excitables ou des ensembles de systèmes neuromimétiques couplés et d'autre part pour contrôler (grâce à l'optogénétique) des canaux ioniques impliqués dans l'émission de potentiels d'action par des neurones de mammifères. Le long du premier chapitre, nous présentons de manière synthétique les concepts dynamiques sur lesquels nous nous appuierons dans la suite du manuscrit. Par la suite, nous décrivons brièvement le contexte de ce travail du point de vue de la synchronisation, notamment de cellules excitables. Enfin, nous discutons le contexte applicatif potentiel de ces travaux, c’est-à-dire l'utilisation de systèmes photoniques dits « neuromimétiques » dans le but de traiter de l'information. Dans le chapitre 2, nous analysons tout d'abord du point de vue théorique et bibliographique le caractère excitable d'un laser à semiconducteur sous l'influence d'un forçage optique cohérent. Par la suite, nous détaillons nos travaux expérimentaux d'abord, puis numériques et théoriques, sur la réponse de ce système « neuromimétique » à des perturbations répétées dans le temps. Tandis que le modèle mathématique simplifié prévoit un comportement de type intégrateur en réponse a des perturbations répétées, nous montrons que le comportement est en fait souvent résonateur, ce qui confère à ce système la propriété étonnante d'émettre une impulsion seulement s'il reçoit deux perturbations séparées d'un intervalle de temps bien précis. Nous montrons également que ce système peut convertir des perturbations de différente intensité en une série d'impulsions toutes identiques mais dont le nombre dépend de l'intensité de la perturbation incidente. Dans le chapitre 3, nous analysons (de nouveau expérimentalement, puis numériquement et théoriquement) le comportement dynamique d'un réseau de lasers à semiconducteur couplés dans un régime de chaos lent-rapide. Nous nous basons sur une étude antérieure montrant qu'un seul de ces éléments peut présenter une dynamique neuromimétique (en particulier l'émission chaotique d'impulsions originant du phénomène de canard). De façon surprenante pour un système ayant un si grand nombre de degrés de liberté, nous observons une dynamique qui semble chaotique de basse dimension. Nous examinons l'impact des propriétés statistiques de la population considérée sur la dynamique et relions nos observations expérimentales et numériques à l'existence d'une variété critique calculable analytiquement pour le champ moyen et près duquel converge la dynamique grâce au caractère lent-rapide du système. Dans le chapitre 4 enfin, nous présentons une brève étude expérimentale de la réponse de cellules biologiques à des perturbations lumineuses. En effet, les techniques optogénétiques permettent de rendre des cellules (en particulier des neurones) sensibles à la lumière grâce au contrôle optique de l'ouverture et de la fermeture de canaux ioniques. Ainsi, après avoir étudié dans les chapitres précédents des systèmes optiques sur la base de considérations provenant de systèmes biologiques, nous amenons matériellement un système laser vers un système biologique
Excitable systems are everywhere in Nature, and among them the neuron, which responds to an external stimulus with an all-or-none type of response, is often regarded as the most typical example. This excitability behaviour is clearly established as to be one of the underlying operating mechanisms of the nervous system and its analysis in model systems (being them mathematical of physical) can, from one hand, shed some light on the dynamics of neural networks, and from the other, open novel ways for a neuro-mimetic treatment of information. The work presented in this PhD thesis was realized in this perspective. In this dissertation we will consider systems based on semiconductor lasers both for modelling excitable systems or coupled neuromorphic networks and for controlling (in an optogenetic outlook) ionic channels that are involved in the emission of action potentials of neurons in mammals. During the first chapter, we will briefly present the dynamical concepts on which we will build our understanding for the rest of the manuscript. Thereafter, we will describe the context of this work from the point of view of synchronized systems, in particular excitable cells. Finally, we will discuss in this context the applications potential of this work, namely the possibility of using “neuromimetic” photonic systems as a was to treat information. In chapter 2 we will firstly analyse from a theoretical and bibliographical standpoint the excitable character of a laser with coherent injection. Later, we will firstly detail our results, firstly experimental and subsequently numerical and theoretical, on the response of this “neuromimetic” system to perturbations repeated in time. Whereas the simplified mathematical model envisions an integrator behaviour in response to repeated perturbations, we will show that the system often acts as a resonator, thus imparting the remarkable property of being able to emit a single pulse only if it receives two perturbations that are separated by a specific time interval. We will also illustrate how this system can convert perturbations of different intensity in a series of all identical pulses whose number depends on the intensity of the incoming perturbation. In the third chapter we will analyse, first experimentally and later numerically and theoretically, the dynamical behaviour of a network of coupled semiconductor lasers in a slow-fast chaotic regime. We will rely on a previous study documenting that a single such element can present a neuromimetic dynamics (in particular, the emission of chaotic pulses originating from a canard phenomenon). Surprisingly for a system having such a large number of degrees of freedom, we observe a dynamics which seems low dimensional chaotic. We will examine the impact of statistical properties of the selected population on the dynamics, and we will link our experimental and numerical observations to the existence of a slow manifold for the mean field, computable analytically, and towards whom the dynamics converges thanks to the slow-fact nature of the system. Finally, in chapter 4 we will present a short experimental study on the response of biological cells to light perturbations. Indeed, optogenetic techniques enables to render the cells (in particular neurons) sensitive to light due to the optical control of the opening and closing of ionic channels. Hence, after having studied in the previous chapters optical systems on the basis of observations derived from biological systems, we will physically transfer an optical system towards a biological one. Here we lay the groundwork of a photonic system which allows, with a moderate complexity, to realize cell measurements in response to spatially localized optical perturbations

In this study, thermocapillary-driven convection around a gas bubble under a horizontal heated wall is experimentally investigated under gravitational conditions. The thermocapillary convective flow under conditions beyond the laminar steady state towards turbulent flow is explored in detail. Generally, Marangoni convection is more critical and important under microgravity conditions rather than on earth. Under low gravity, this surface tension induced flow can dictate both heat and mass transfer processes. Thus, thermocapillary convection should be considered by manufacturers during material production processes in space. Moreover, temperature gradients can be purposefully used to eliminate or move bubbles or drops suspended in liquid materials. In addition to that, thermocapillary convective flow appears in many other applications like manufacturing of single-walled carbon nanotubes and mono crystal production, to mention only few examples. Researchers have always seen Marangoni convection as an interesting topic for both numerical and experimental studies. Regarding the configuration of the injected gas bubble under a horizontal heated wall, this physical problem is mainly characterized by a dimensionless number that represents the ratio of convective heat flow induced by capillary convection to the heat transfer due to conduction which is termed Marangoni number (Mg). The past decade has seen different approaches to describe the flow behaviour at high Marangoni numbers. The thermocapillary flow has been mainly investigated and categorized regarding a stable laminar behaviour and a non-laminar one, which is characterized by periodic or non-periodic oscillations. Through previous studies, the point of the transition of the thermocapillary flow from the periodic oscillatory zone to the non-periodic one has been well investigated. However, there is a lack of information about this non-periodic behaviour at very high temperature gradients. Therefore, in the current study, our experimental investigations focus mainly on exploring different factors affecting the non-periodicity of the Marangoni convection and on explaining how this flow behaves under conditions above the transitional Marangoni number (Mg tran ). The experimental work was launched using a PIV technique and shadowgraphy. In addition to that, temperature measurements at different locations in the matrix fluid around the air bubble were conducted to determine the undisturbed temperature gradients at different boundary conditions. The transient observation of both velocity and temperature measurements at locations near the bubble allowed deeper insight in the behaviour of the thermocapillary bubbleconvection. Moreover, through shadowgraphy, a qualitative evaluation of the fluid flow periodicity around the gas bubble was achieved. The implementation of experiments inside a pressure chamber under gauge pressure conditions formed a novel methodology to enable us conducting experiments under higher temperature gradients in order to reach high Marangoni numbers. The thermocapillary bubble convection was categorized into laminar, periodic oscillatory, and non-periodic oscillatory flow. The periodic fluid flow oscillations were categorized in symmetric and asymmetric ones depending on the different applied boundary conditions. The non-periodic fluid flow oscillations around the gas bubble were also achieved at high temperature gradients for different bubble aspect ratios. We proved that for every bubble size, the non-periodic oscillatory state of the fluid flow around the gas bubble undergoes four different modes (A-D). The last one (phase D) is a developed turbulent state starting at Mg- numbers of 75000 for the smallest bubble aspect ratio of 1.2 up to the maximal measured Mg- number of 140000 for a bubble aspect ratio of 2.3. Hence, turbulent thermocapillary bubble convection was realized and studied in our experimental configuration. Moreover, the thermocapillary flow driving velocities at the bubble periphery were measured at different boundary conditions. This study clearly demonstrates that it is the high magnitude of the driving velocity that initiates the interactions between thermocapillary flow vortices leading finally to a highly developed oscillation mode (turbulent state) and that buoyancy plays a secondary role in the described flow configuration.:1 INTRODUCTION 2 LITERATURE REVIEW 3 EXPERIMENTAL SETUP AND METHODOLOGY 4 RESULTS AND DISCUSSION 5 CONCLUSIONS AND RECOMMENDATIONS
In dieser Arbeit wird die thermokapillare Konvektion um eine Gasblase unter einer horizontal beheizten Wand unter Gravitationsbedingungen experimentell untersucht. Diese thermokapillare konvektive Strömung jenseits des laminaren stationären Zustands in Richtung turbulenter Strömung steht in dieser Arbeit im Fokus. Im Allgemeinen ist die Marangoni-Konvektion unter Schwerelosigkeitsbedingungen kritischer und wichtiger als auf der Erde. Unter geringen Schwerkraftkräften kann diese durch Oberflächenspannung induzierte Strömung sowohl Wärme- als auch Stoffübergangsprozesse maßgeblich bestimmen. Daher sollte die thermokapillare Konvektion bei Materialproduktionsprozessen im Weltraum berücksichtigt werden. Darüber hinaus können Temperaturgradienten gezielt angewendet werden, um in flüssigen Materialien suspendierte Blasen oder Tropfen zu entfernen oder zu bewegen. Außerdem tritt thermokapillare Strömung in vielen anderen Anwendungen auf, beispielsweise bei der Herstellung von einwandigen Kohlenstoffnanoröhren oder der Herstellung von Einkristallen, um nur einige Beispiele zu nennen. Forscher haben die Marangoni-Konvektion immer als ein wichtiges und interessantes Thema für numerische und experimentelle Studien betrachtet. In Bezug auf die Konfiguration der injizierten Blase unter einer horizontal beheizten Wand wird dieses physikalische Problem hauptsächlich durch eine dimensionslose Kennzahl, die das Verhältnis des durch Kapillarkonvektion induzierten konvektiven Wärmeübertragungs zur Wärmeübertragung durch Leitung darstellt und als Marangoni-Zahl (Mg) bezeichnet wird, definiert. In den letzten Jahrzehnten wurden verschiedene Ansätze zur Beschreibung des Strömungs-Verhaltens bei höheren Marangoni-Zahlen verfolgt. Dabei wurde die Thermokapillarströmung grundsätzlich in ein stabiles laminares und ein nicht laminares (oszillierendes) Verhalten, das durch periodische oder nicht periodische Geschwindigkeit- und Temperatur-Fluktuationen gekennzeichnet ist, eingeteilt. Durch frühere Studien wurde das Regime des Übergangs des thermokapillaren Verhaltens von der periodischen Schwingungszone zur nichtperiodischen gut untersucht. Es fehlen jedoch immer noch detaillierte Informationen über das nichtperiodische Verhalten bei sehr hohen Temperaturgradienten. Daher konzentrieren sich unsere experimentellen Untersuchungen in der vorliegenden Studie hauptsächlich auf die Untersuchung verschiedener Faktoren, die die Nichtperiodizität der konvektiven Thermokapillarströmung beeinflussen, und auf eine Klärung, wie sich diese Strömung unter verschiedenen Randbedingungen über der kritischen Marangoni-Zahl (Mg c ) verhält.Die experimentelle Arbeit wurde sowohl mit einer PIV-Technik als auch mit der Shadowgraph- Technik durchgeführt. Darüber hinaus waren Temperaturmessungen auf Sensorbasis an verschiedenen Stellen in der verwendeten Flüssigkeit um die Luftblase geeignet, um die ungestörten Temperaturgradienten bei verschiedenen Randbedingungen zu bestimmen. Die zeitabhängige Messung sowohl von Geschwindigkeiten als auch von Temperaturen an Orten in der Nähe der Blase lieferte Informationen über das Verhalten der Konvektion der thermokapillaren Strömung. Darüber hinaus wurde durch die Shadowgraph-Technik eine qualitative Bewertung der Fluidströmungsperiodizität um die Blase ermöglicht. Die Durchführung von Experimenten in einer Druckkammer unter Überdruck-Bedingungen bildet eine neuartige Methode, um solche Experimente unter höheren Temperaturgradienten durchzuführen und höhere Marangoni-Zahlen zu erreichen. Die thermokapillare Blasenkonvektion wurde in dieser Arbeit in laminaren stetigen Flüssigkeitsströmungen, periodischen und nichtperiodischen oszillierenden Flüssigkeitsströmungen eingeteilt. Die periodischen Fluidströmungsschwingungen wurden in Abhängigkeit von unterschiedlichen Randbedingungen in symmetrische und asymmetrische eingeteilt. Die nichtperiodischen Strömungsoszillationen um die Gasblase wurden auch bei hohen Temperaturgradienten für verschiedene Blasenaspektverhältnisse erreicht. Wir konnten zeigen, dass für jede Blasengröße der nichtperiodische Schwingungszustand der Strömung um die Gasblase vier verschiedene Modi (A-D) besitzen kann. Die letzte (Phase D) ist ein hoch entwickelter turbulenter Zustand, der bei Mg-Zahlen von 75000 für das kleinste Blasenaspektverhältnis von 1,2 bis zur maximal gemessenen Mg-Zahl von 140000 für das Blasenaspektverhältnis von 2,3 beginnt. Der ausgebildete turbulente Zustand der thermokapillaren Strömung konnte mit unserer experimentellen Konfiguration erstmalig erreicht werden. Darüber hinaus konnten die Antriebsgeschwindigkeiten der thermokapillaren Strömung an der Peripherie der Blase bei verschiedenen Randbedingungen gemessen werden. Diese Studie zeigt deutlich, dass es die Höhe der Antriebsgeschwindigkeit ist, welche die Wechselwirkungen zwischen thermokapillaren Strömungswirbeln unterschiedlicher Größe antreibt, die schließlich zu chaotischen Schwingungen der im Folgenden beschriebenen Grenzlinie führen. Diese Studie zeigt auch, dass die Auftriebskonvektion in der beschriebenen Strömungskonfiguration eine untergeordnete Rolle spielt.:1 INTRODUCTION 2 LITERATURE REVIEW 3 EXPERIMENTAL SETUP AND METHODOLOGY 4 RESULTS AND DISCUSSION 5 CONCLUSIONS AND RECOMMENDATIONS

Ce travail de thèse porte sur l'étude de l'intégration des fonctions d'amortissement vibroacoustique dans des plaques en matériau composite. Dans un premier temps, pour une méta-plaque non composite, les caractéristiques d'atténuation des vibrations ont été étudiées avec un réseau périodique de résonateurs (poutre-masse) attachés à une plaque.L'effet de périodicité et des résonances locales permet de bloquer la propagation d'ondes sur des plages de fréquences données, appelée bandes interdites. Des simulations numériques basées sur la MEF ont permis de calculer les diagrammes de bandes des plaques périodiques et d'analyser la sensibilité de ces bandes interdites aux différents paramètres de conception de méta-plaque. Les calculs de coefficient de transmission d'une onde plane selon la direction perpendiculaire à la zone traitée, mettent en évidence la présence des bandes interdites prédites par le diagramme de bande. Les réponses fréquentielles de plusieurs modèles sont comparées, pour mettre en évidence les écarts entre une structure infinie et une structure finie. Une méthode automatique originale est mise au point pour détecter les gammes de fréquences des bandes interdites pour une méta-plaque finie.Ces méthodes théorique et expérimentale sont alors appliquées à des plaques composites SMC avec des perforations périodiques. Des essais avec une excitation unidirectionnelle et une excitation ponctuelle sont réalisés. L'influence de chaque type de sollicitation sur la réponse vibratoire des plaques est analysée pour mettre en évidence la détectabilité des bandes interdites. Enfin, la robustesse des bandes interdites aux variations du réseau périodique est validée
The vibration attenuation characteristics of a metamaterial plate were investigated theoretically and experimentally with a 2-dimensional periodic array of resonators (mass-beam) attached to a thin homogeneous plate.The sensitivity analysis of the band gap frequency range took into account the uncertainties of all the design parameters of the metamaterial plate. The theoretical approach used the finite element method (FEM) to compare the predicted band gaps with those derived from infinite and finite models of the metamaterial.An original automatic method is proposed to detect the frequency ranges of band gaps in finite metamaterial based on the behavior of the corresponding bare plate. Directional plane wave excitation and point force excitation were applied to evaluate the efficiency of the detection method. The results of these analyses were compared with experimental measurements. Frequency ranges of experimental vibration attenuation are in good agreement with the theoretically predicted complete and directional band gaps.These theoretical and experimental methods are then applied to SMC (Sheet Molding Compound) composite plates with periodic perforations. Tests with unidirectional excitation and point force excitation are performed. The influence of each type of excitation on the vibratory response of the plates is analyzed in order to demonstrate the detectability of the bands gaps.Finally, the robustness of the band gap to the variations of the periodic lattice is validated following an integration of perturbations: addition of local mass on half of the unit cells according to a periodic or random positions

This thesis is concerned with nonlinear analyses of BWR stability behaviour, contributing to a deeper understanding in this field. Despite negative feedback-coefficients of a BWR, there are operational points (OP) at which oscillatory instabilities occur. So far, a comprehensive and an in-depth understanding of the nonlinear BWR stability behaviour are missing, even though the impact of the significant physical parameters is well known. In particular, this concerns parameter regions in which linear stability indicators, like the asymptotic decay ratio, lose their meaning. Nonlinear stability analyses are usually carried out using integral (system) codes, describing the dynamical system by a system of nonlinear partial differential equations (PDE). One aspect of nonlinear BWR stability analyses is to get an overview about different types of nonlinear stability behaviour and to examine the conditions of their occurrence. For these studies the application of system codes alone is inappropriate. Hence, in the context of this thesis, a novel approach to nonlinear BWR stability analyses, called RAM-ROM method, is developed. In the framework of this approach, system codes and reduced order models (ROM) are used as complementary tools to examine the stability characteristics of fixed points and periodic solutions of the system of nonlinear differential equations, describing the stability behaviour of a BWR loop. The main advantage of a ROM, which is a system of ordinary differential equations (ODE), is the possible coupling with specific methods of the nonlinear dynamics. This method reveals nonlinear phenomena in certain regions of system parameters without the need for solving the system of ROM equations. The stability properties of limit cycles generated in Hopf bifurcation points and the conditions of their occurrence are of particular interest. Finally, the nonlinear phenomena predicted by the ROM will be analysed in more details by the system code. Hence, the thesis is not focused on rendering more precisely linear stability indicators like DR. The objective of the ROM development is to develop a model as simple as possible from the mathematical and numerical point of view, while preserving the physics of the BWR stability behaviour. The ODEs of the ROM are deduced from the PDEs describing the dynamics of a BWR. The system of ODEs includes all spatial effects in an approximated (spatial averaged) manner, e.g. the space-time dependent neutron flux is expanded in terms of a complete set of orthogonal spatial neutron flux modes. In order to simulate the stability characteristics of the in-phase and out-of-phase oscillation mode, it is only necessary to take into account the fundamental mode and the first azimuthal mode. The ROM, originally developed at PSI in collaboration with the University of Illinois (PSI-Illinois-ROM), was upgraded in significant points: • Development and implementation of a new calculation methodology for the mode feedback reactivity coefficients (void and fuel temperature reactivity) • Development and implementation of a recirculation loop model; analysis and discussion of its impact on the in-phase and out-of-phase oscillation mode • Development of a novel physically justified approach for the calculation of the ROM input data • Discussion of the necessity of consideration of the effect of subcooled boiling in an approximate manner With the upgraded ROM, nonlinear BWR stability analyses are performed for three OPs (one for NPP Leibstadt (cycle7), one for NPP Ringhals (cycle14) and one for NPP Brunsbüttel (cycle16) for which measuring data of stability tests are available. In this thesis, the novel approach to nonlinear BWR stability analyses is extensively presented for NPP Leibstadt. In particular, the nonlinear analysis is carried out for an operational point (OP), in which an out-of-phase power oscillation has been observed in the scope of a stability test at the beginning of cycle 7 (KKLc7_rec4). The ROM predicts a saddle-node bifurcation of cycles, occurring in the linear stable region, close to the KKLc7_rec4-OP. This result allows a new interpretation of the stability behaviour around the KKLc7_rec4-OP. The results of this thesis confirm that the RAM-ROM methodology is qualified for nonlinear BWR stability analyses
Die vorliegende Dissertation leistet einen Beitrag zum tieferen Verständnis des nichtlinearen Stabilitätsverhaltens von Siedewasserreaktoren (SWR). Trotz der Tatsache, dass in diesem technischen System nur negative innere Rückkopplungskoeffizienten auftreten, können in bestimmten Arbeitspunkten oszillatorische Instabilitäten auftreten. Obwohl relativ gute Kenntnisse über die signifikanten physikalischen Einflussgrößen vorliegen, fehlt bisher ein umfassendes Verständnis des SWR-Stabilitätsverhaltens. Das betrifft insbesondere die Bereiche der Systemparameter, in denen lineare Stabilitätsindikatoren, wie zum Beispiel das asymptotische Decay Ratio (DR), ihren Sinn verlieren. Die nichtlineare Stabilitätsanalyse wird im Allgemeinen mit Systemcodes (nichtlineare partielle Differentialgleichungen, PDG) durchgeführt. Jedoch kann mit Systemcodes kein oder nur ein sehr lückenhafter Überblick über die Typen von nichtlinearen Phänomenen, die in bestimmten System-Parameterbereichen auftreten, erhalten werden. Deshalb wurde im Rahmen der vorliegenden Arbeit eine neuartige Methode (RAM-ROM Methode) zur nichtlinearen SWR-Stabilitätsanalyse erprobt, bei der integrale Systemcodes und sog. vereinfachte SWR-Modelle (ROM) als sich gegenseitig ergänzende Methoden eingesetzt werden, um die Stabilitätseigenschaften von Fixpunkten und periodischen Lösungen (Grenzzyklen) des nichtlinearen Differentialgleichungssystems, welches das Stabilitätsverhalten des SWR beschreibt, zu bestimmen. Das ROM, in denen das dynamische System durch gewöhnliche Differentialgleichungen (GDG) beschrieben wird, kann relativ einfach mit leistungsfähigen Methoden aus der nichtlinearen Dynamik, wie zum Beispiel die semianalytische Bifurkationsanalyse, gekoppelt werden. Mit solchen Verfahren kann, ohne das DG-System explizit lösen zu müssen, ein Überblick über mögliche Typen von stabilen und instabilen oszillatorischen Verhalten des SWR erhalten werden. Insbesondere sind die Stabilitätseigenschaften von Grenzzyklen, die in Hopf-Bifurkationspunkten entstehen, und die Bedingungen, unter denen sie auftreten, von Interesse. Mit dem Systemcode (RAMONA5) werden dann die mit dem ROM vorhergesagten Phänomene in den entsprechenden Parameterbereichen detaillierter untersucht (Validierung des ROM). Die Methodik dient daher nicht der Verfeinerung der Berechnung linearer Stabilitätsindikatoren (wie das DR). Das ROM-Gleichungssystem entsteht aus den PDGs des Systemcodes durch geeignete (nichttriviale) räumliche Mittelung der PDG. Es wird davon ausgegangen, dass die Reduzierung der räumlichen Komplexität die Stabilitätseigenschaften des SWR nicht signifikant verfälschen, da durch geeignete Mittlungsverfahren, räumliche Effekte näherungsweise in den GDGs berücksichtig werden. Beispielsweise wird die raum- und zeitabhängige Neutronenflussdichte nach räumlichen Moden entwickelt, wobei für eine Simulation der Stabilitätseigenschaften der In-phase- und Out-of-Phase-Leistungsoszillationen nur der Fundamentalmode und der erste azimuthale Mode berücksichtigt werden muss. Das ROM, welches ursprünglich am Paul Scherrer Institut (PSI, Schweiz) in Zusammenarbeit mit der Universität Illinois (USA) entwickelt wurde, ist in zwei wesentlichen Punkten erweitert und verbessert worden: • Entwicklung und Implementierung einer neuen Methode zur Berechnung der Rückkopplungsreaktivitäten • Entwicklung und Implementierung eines Modells zur Beschreibung der Rezirkulationsschleife (insbesondere wurde der Einfluss der Rezirkulationsschleife auf den In-Phase-Oszillationszustand und auf den Out-of-Phase-Oszillationszustand untersucht) • Entwicklung einer physikalisch begründeten Methode zur Berechnung der ROM-Inputdaten • Abschätzung des Einflusses des unterkühlten Siedens im Rahmen der ROM-Näherungen Mit dem erweiterten ROM wurden nichtlineare Stabilitätsanalysen für drei Arbeitspunkte (KKW Leibstadt (Zyklus 7) KKW Ringhals (Zyklus 14) und KKW Brunsbüttel (Zyklus 16)), für die Messdaten vorliegen, durchgeführt. In der Dissertationsschrift wird die RAM-ROM Methode ausführlich am Beispiel eines Arbeitspunktes (OP) des KKW Leibstadt (KKLc7_rec4-OP), in dem eine aufklingende regionale Leistungsoszillation bei einem Stabilitätstest gemessen worden ist, demonstriert. Das ROM sagt die Existenz eines Umkehrpunktes (saddle-node bifurcation of cycles, fold-bifurcation) voraus, der sich im linear stabilen Gebiet nahe der Stabilitätsgrenze befindet. Mit diesem ROM-Ergebnis ist eine neue Interpretation der Stabilitätseigenschaften des KKLc7_rec4-OP möglich. Die Resultate der in der Dissertation durchgeführten RAM-ROM Analyse bestätigen, dass das weiterentwickelte ROM für die Analyse des Stabilitätsverhaltens realer Leistungsreaktoren qualifiziert wurde

Cette thèse traite de certaines propriétés spectrales de deux classes spécifiques des opérateurs périodiques. Nous nous intéressons tout d’abord à un modèle périodique perturbée par un opérateur dépendant d’un petit paramètre semi-classique. Nous obtenons alors le comportement asymptotique de la fonction du comptage des valeurs propres dans les gaps spectrales avec une estimation optimale du reste. Le second modèle étudié dans cette thèse est un modèle elliptique périodique d’ordre deux perturbée par un opérateur dépendant d’une grande constante de couplage. Nous donnons également la description de la fonction de compactage des valeurs propres lorsque la constante de couplage tend vers l’infini. La dernière partie de cette thèse discute l’étude du spectre discret de l’opérateur de Schrödinger avec un potentiel très oscillent dépendant d’un petit paramètre semi-classique
This Ph.D thesis deals with some spectral properties of two specific classes of two periodic operators. We are firstly interested in the model periodic perturbed by operator depending on a small semi-classical constant. We obtain an asymptotic behavior of the eigenvalue counting function in the spectral gaps with scharp remainder estimate. The second model studied in this thesis is a two-dimensional periodic elliptic second order opera-tor perturbed by operator depending on a large coupling constant. We also give the description of the counting function of eigenvalues when the coupling constant tends to infinity. The last part of this thesis highlights the study the spectrum of a Schrödinger operator perturbed by a fast oscillatingdecaying potential depending on a small parameter

Ces travaux s'articulent autour du calcul des solutions périodiques dans les systèmes dynamiques non linéaires, au moyen de méthodes numériques de continuation. La recherche de solutions périodiques se traduit par un problème avec conditions aux limites périodiques, pour lequel nous avons implémenté deux méthodes d'approximation : - Une méthode spectrale dans le domaine fréquentiel : l'équilibrage harmonique d'ordre élevé, qui repose sur une formulation quadratique des équations. Nous proposons en outre une formulation originale permettant d'étendre cette méthode aux cas de non-linéarités non rationnelles. - Une méthode pseudo-spectrale par éléments dans le domaine temporel : la collocation à l'aide fonctions polynômiales par morceaux. Ces méthodes transforment le problème continu en un système d'équations algébriques non linéaires, dont les solutions sont calculées par continuation à l'aide de la méthode asymptotique numérique. L'ensemble de ces outils, intégrés au code de calcul MANLAB et complétés d'une analyse linéaire de stabilité, sont alors utilisés pour l'étude des régimes périodiques d'une classe particulière de systèmes dynamiques non linéaires : les instruments de musique auto-oscillants. Un modèle physique non-régulier de clarinette est étudié en détail : à partir de la branche de solutions statiques et ses bifurcations, on calcule les différentes branches de solutions périodiques, ainsi que leur stabilité et leurs bifurcations. Ce modèle est ensuite adapté au cas du saxophone, pour lequel on intègre une caractérisation acoustique expérimentale, afin de mieux tenir compte de la géométrie complexe de l'instrument. Enfin, nous étudions un modèle physique simplifié de violon, avec une non-régularité liée frottement de Coulomb. Cette dernière application illustre ainsi la polyvalence des outils développés face aux différents types de non-régularité.

碩士
國立中正大學
光機電整合工程所
96
A numerical study on all-optical frequency conversion on nonlinear dynamical period-one oscillations of optically injected semiconductor lasers is presented in this thesis. wavelength conversion is demonstrated at 2.5 GHz over a wavelength span of 50GHz by the use of period-one oscillation in optical injection configuration. An increase in the signal to noise ratio is measured for the converted signal compared to the input signal implying signal regeneration as well as wavelength conversion.

碩士
國立中正大學
光機電整合工程所
97
A numerical study of semiconductor lasers external optical injection lock system, master laser modulated response based on period one oscillation condition is presented in this thesis. An evluation for novel application in ROF system also presented in this work. Modulation parameters such as modulation index (MI), frequency modulation index ( ), frequency deviation ( ) are investigated to help us understand the amplitude/frequency modulated response of this system. Also the frequency response of modulation frequency for this optical communication generation, 2.5GHz modulation frequency is analyzed based on different operation parameter.

碩士
國立中正大學
光機電整合工程所
97
The thesis is individually done by way of numerical simulation analysis to research nonlinear dynamical periodic-one oscillation of optical injected semiconductor lasers. By means of injection continuous optical signal, it discusses the relation between the differently operative point and conversion efficiency or transmission efficiency. Also, the thesis discusses how the laser noise affect nonlinear dynamical periodic-one oscillation of optical injected semiconductor lasers. And changing the operative point to better conversion efficiency or transmission efficiency.

碩士
國立交通大學
應用數學系數學建模與科學計算碩士班
101
In this thesis, we study the periods and amplitudes in coupled oscillations. The study is motivated by some interesting investigations in mathematical models on biological clocks. Herein, we couple two oscillators, and use the Hopf bifurcation theorem to show that the coupled oscillation is sustained. We observe the relation between the collective period and the isolated individual periods. We also study the amplitudes of oscillations in coupled systems. In particular, we discuss the oscillations in three-cell feed-forward by Golubitsky and collaborators, where synchrony-breaking Hopf bifurcations may happen in some feed-forward network, and amplify the periodic signals. We summarize these results, and extend the study to the variation of amplitudes in a four-cell feed-forward chain. Finally, we give some numerical simulation to illustrate our results.

碩士
國立中正大學
光機電整合工程所
94
ABSTRACT A numerical study on effects of laser parameters on period-one oscillations of optically injected semiconductor lasers is presented in this thesis. In this study, nonlinear dynamics、frequency separation、intensity difference、conversion efficiency、transmission efficiency as a function of laser parameters are investigated and discussed to assess suitability for frequency converter due to period-one oscillations spectrum characteristic is similar to frequency conversion. Nonlinear dynamics of an optically injected semiconductor laser is mapped as a function of injection parameter (ξ) and detuning frequency (f). Variation in the normalize bias current ( ) and intrinsic parameters ( 、 、 ， ) are observed have some effects on the dynamics of the system.

碩士
國立清華大學
光電工程研究所
96
We numerically simulated signal generation for range and velocity detecction utilizing optically injected (OI) system. OI system consists of a master laser and a slave laser. By tuning the operating parameters, the optically injected semiconductor laser can be operated in different instable regions. There are stable-locking, chaotic oscillation (CO), period-one oscillation (P1), period-two oscillation (P2) and high order oscillation regions. We research the radar for range and velocity detection with P1 state. For range detection, two schemes will be used to generate linearly chirped signal. One is directly modulating the injection strength of slave laser, and the other is indirectly modulating the injection strength of slave laser. After mixing transmitting signal and refected signal, the mixing signal can be used to evaluate the range of the target. We investigate the effect of bandwidth, period, and noise on the linewidth that determinates the resolution of the signal. By simulation, the resloution is 0.753 m utilizing directly modulating the injection strength of slave laser, and the resolution is 1.087 m utilizing indirectly modulating the injection strength of slave laser. In comparison, the resolution of the former is better than the latter. For velocity detection, there is Doppler-shift frequency when the target is moving, and we can evaluate the velocity of the target. By double-lock technology, the linewidth can be reduced with MSF. We evaluate that the resolution is 4.5 μm/s with the hypotheses. When the target moves sinusoidally or as a triangular wave, we research the relation between Doppler-shift frequency and the ratio of the target moving amplitude and the mircowave wavelength.

碩士
國立臺灣科技大學
電機工程系
99
A time-to-digital converter (TDC) plays an important role in time period measurement. Many kinds of TDC structure were developed for different requirements. Among them, the vernier-based time-to-digital converter is the best in terms of highly accurate time resolution. However, the input time period cannot exceed a period of the reference clock for the conventional vernier-based TDC. Therefore, a TDC structure that employs three PLL as reference clocks was purposed in literature for increasing the range of allowable time period. However it needs complicated calibration procedure. This makes it difficult in use practically. In this thesis, we purpose a new oscillation circuit for the TDC, a soft-injection-locked ring oscillator. It can oscillate immediately right after the trigger signal arrives. For measuring a long period of time, the deviation is less than 0.01% with correction formula. Moreover, the TDC structure employing the purposed oscillator can be implemented in 40- and 74-series ICs. Compared with the full-custom design flow or FPGA, the TDC in this thesis can be verified quickly and possesses very low manufacturing coast.

The cell division cycle is the process in which the entirety of a cell's contents is duplicated completely and then equally segregated into two identical daughter cells. The order of the steps in the cell cycle must be followed with fidelity to guarantee two viable cells. Understanding the regulatory mechanisms that control cell-cycle events remains to be a fundamental question in cell biology. In this dissertation, I explore the mechanisms that coordinate and regulate cell-cycle progression in the budding yeast, Saccharomyces cerevisiae.

Cell-cycle events have been shown to be triggered by oscillations in the activity of cyclin dependent kinases (CDKs) when bound to cyclins. However, several studies have shown that some cell-cycle events, such as periodic transcription, can continue in the absence of CDK activity. How are periodic transcription and other cell-cycle events coupled to each other during a wild-type cell cycle? Currently, two models of cell-cycle regulation have been proposed. One model hypothesizes that oscillations in CDK activity controls the timing of cell-cycle events, including periodic transcription. The second model proposes that a transcription factor (TF) network oscillator controls the timing of cell-cycle events, via proper timing of gene expression, including cyclins. By measuring global gene expression dynamics in cells with persistent CDK activity, I show that periodic transcription continues. This result fits with the second model of cell-cycle regulation. Further, I show that during a wild-type cell cycle, checkpoints are responsible for arresting the bulk of periodic transcription. This finding adds a new layer of regulation to the second model, providing a mechanism that coordinates cell-cycle events with a TF network oscillator. Taken together, these data provide further insight into the regulation of the cell cycle.

Dissertation