This thesis considers four nonlinear systems with parametric forcing. The first problem involves an inverted pendulum with asymmetric elastic restraints subjected to harmonic vertical base excitation. On linearizing trigonometric terms the pendulum is governed by an asymmetric Mathieu equation. Solutions to this equation are scaleable. The stability regions in the parameter plane are studied numerically. Periodic solutions at the boundaries of stable regions in the parameter plane are found numerically and then their existence is proved theoretically. The second problem involves use of the method of multiple scales to elucidate the dynamics associated with early and delayed ejection of ions from Paul traps. A slow flow equation is developed to approximate the solution of a weakly nonlinear Mathieu equation to describe ion dynamics in the neighborhood of the nominal stability boundary of ideal traps. Since the solution to the unperturbed equation involves linearly growing terms, some care in identification and elimination of secular terms is needed. Due to analytical difficulties, harmonic balance approximations are used within the formal implementation of the method. The third problem involves the attenuation, caused by weak damping, of harmonic waves through a discrete, periodic structure with wave frequency nominally within the Propagation Zone. Adapting the transfer matrix method and using the harmonic balance for nonlinear terms, a four-dimensional map governing the dynamics is obtained. This map is analyzed by applying the method of multiple scales upto first order. The resulting slow evolution equations give the amplitude decay rate in the structure. The fourth problem involves the dynamic response of a strongly nonlinear single-degree-of-freedom oscillator under a constant amplitude, parametric, periodic, impulsive forcing, e.g., a pendulum with strongly nonlinear torsional spring that is periodically struck in the axial direction. Single-term harmonic balance gives an approximate, but explicit, 2-dimensional map governing the dynamics. The map exhibits many fixed points (both stable and unstable), higher period orbits, transverse intersections of stable and unstable manifolds of unstable fixed points, and chaos.

Iki 2003 m. LR BK normose buvo numatytas, tik žmogaus laisvės pasirinkti buvimo vieta varžymas. Tuo tarpu kėsinimasis i žmogaus laisvę pasirinkti, elgesio varianta LR BK išvis nebuvo reglamentuotas. 2003 m. įsigaliojus naujam Baudžiamajam kodeksui, jo 148 str. buvo numatyta nauja nusikalstamos veikos sudėtis - žmogaus veiksmų laisvės varžymas. Naujas požiūris į žmogaus laisvę atitiko visuomeninių santykių realijas ir tarptautinius Lietuvos įsipareigojimus, tačiau šios normos taikymas tapo problematiškas dėl jos naujumo ir požymiu neaiškumo. Šiame darbe atskleidžiama žmogaus veiksmu laisvės samprata įvairiu istoriniu laikotarpiu. Pateiktas šios sampratos filosofinis ir teisinis aiškinimas. Aptariamos teisinės žmogaus veiksmų laisvės sampratos ištakos, teisinio apibrėžtumo būtinumas ir įstatyminis šios sampratos reglamentavimas, ne tik Lietuvos, bet ir užsienio šalių baudžiamuosiuose įstatymuose, bei tarptautiniuose teisės aktuose. Nurodomi žmogaus veiksmų laisvės sampratos teisinio reglamentavimo trūkumai Lietuvos baudžiamuosiuose įstatymuose. Darbe pateikta šiuo metu galiojančios LR BK 148 str. normos objektyviųjų ir subjektyviųjų požymių analizė. Šios normos teisinio vertinimo ypatumai atskleisti analizuojant ryšius su kitomis, savo sudėties požymiais panašiomis nusikalstamomis veikomis. Normos teisinio įvertinimo problemos aptariamos ne tik moksliniu, teisminiu aiškinimu, tačiau panaudota ir teismų praktikos pavyzdžiai. Darbe pateikta žmogaus veiksmų laisvės varžymo normos... [to full text] / Until the year 2003, only the restriction on a person’s freedom to choose the place of residence was provided for in the Criminal Code of the Republic of Lithuania, whereas the infringement of a person’s freedom of action was not regulated at all. In 2003, when the new Criminal Code became effective, a new criminal act – the restriction on a person’s freedom of action was established in Article 148 of the Code. A new approach towards the freedom of a person was in line with the currently existing public relations and international Lithuanian covenant but the application of this norm was quite complicated due to the fact that it was new and its elements were not clearly defined. This paper reveals the understanding of a person’s freedom of action in various historical periods. A philosophical and legal definition and explanation of this concept is presented here. The beginnings of legal understanding of a person’s freedom of action, the necessity for a legal definition and statutory regulation of this concept not only in the Lithuanian but also in foreign criminal laws and international legal acts are discussed. The shortcomings of legal regulation of the concept of a person’s freedom of actions in the Lithuanian criminal laws are highlighted. The analysis of objective and subjective elements of the norm, stipulated in the currently effective Article 148 of the Criminal Code of the Republic of Lithuania, is presented in this paper. The specific features of legal appraisal... [to full text]

A lack of quality data on high clouds has led to inadequate representations within global weather and climate models. Recent advances in spaceborne measurements of the Earth’s atmosphere have provided complementary information on the interior of these clouds. This study demonstrate how an array of space-borne measurements can be used and combined, by close co-located comparisons in space and time, to form a more complete representation of high cloud processes and properties. High clouds are found in the upper atmosphere, where sub-zero temperatures frequently result in the formation of cloud particles that are composed of ice. Weather and climate models characterise the bulk properties of these ice particles to describe the current state of the cloud-sky atmosphere. By directly comparing measurements with simulations undertaken at the same place and time, this study demonstrates how improvements can be made to the representation of cloud properties. The results from this study will assist in the design of future cloud missions to provide a better quality input. These improvements will also help improve weather predictions and lower the uncertainty in cloud feedback response to increasing atmospheric temperature. Most clouds are difficult to monitor by more than one instrument due to continuous changes in: large-scale and sub-cloud scale circulation features, microphysical properties and processes and characteristic chemical signatures. This study undertakes co-located comparisons of high cloud data with a cloud ice dataset reported from the Microwave Limb Sounder (MLS) instrument onboard the Aura satellite that forms part of the A-train constellation. Data from the MLS science team include vertical profiles of temperature, ice water content (IWC) and the mixing ratios of several trace gases. Their vertical resolutions are 3 to 6 km. Initial investigations explore the link between cloud-top properties and the longwave radiation budget, developing methods for estimating cloud top heights using; longwave radiative fluxes, and IWC profiles. Synergistic trios of direct and indirect high cloud measurements were used to validate detections from the MLS by direct comparisons with two different A-train instruments; the NASA Moderate-resolution Imaging Spectroradiometer (MODIS) and the Clouds and the Earth’s Radiant Energy System (CERES) onboard on the Aqua satellite. This finding focuses later studies on two high cloud scene types that are well detected by the MLS; deep convective plumes that form from moist ascent, and their adjacent outflows that emanate outwards several hundred kilometres. The second part of the thesis identifies and characterises two different high cloud scenes in the tropics. Direct observational data is used to refine calculations of the climate sensitivity to upper tropospheric humidity and high cloud in different conditions. The data reveals several discernible features of convective outflows are identified using a large sample of MLS data. The key finding, facilitated by the use of co-location, reveals that deep convective plumes exert a large longwave warming effect on the local climate of 52 ± 28Wm−2, with their adjacent outflows presenting a more modest warming of 33 ± 20Wm−2.

Increases in the frequency and magnitude of extreme water levels and storm surges are observed along some areas of the British Columbia coast to be correlated with known climatic variability (CV) phenomena, including the El Niño/Southern Oscillation (ENSO) and the Pacific Decadal Oscillation (PDO). Since a shift to a positive PDO regime in 1977, the effect of ENSO events have been more frequent, persistent, and intense. Teleconnected impacts include more frequent storms, higher surges, and greater coastal erosion. Geomorphic recovery of regional beach-dune systems from erosive events is usually rapid (i.e., within a year) by way of high onshore sand transport and aeolian delivery to the upper beach and dunes. At Wickaninnish Bay on the west coast of Vancouver Island, fast progradation rates (to +1.46 m a-1) have been observed in recent decades, in part due to rapid regional tectonic uplift and a resulting fall in relative sea level of ~ -0.9 mm a-1. The Wickaninnish foredune complex has rapidly extended alongshore in response to a net northward littoral drift and onshore sediment delivery. Bar deposition and welding processes supply sediment to the foredune complex via aeolian processes, and as a result, this is forcing Sandhill Creek northward toward the prograding (+0.71 m a-1) Combers Beach system, in part maintaining active erosion (-1.24 m a-1) of a bluff system landward of the channel. Bluff erosion generates substantial sediment volumes (-0.137 m3 m-2 a-1) that feed a large intertidal braided channel and delta system as the creek purges into the Pacific Ocean. As a first step in exploring the interactions between ocean-atmosphere forcing and beach-dune responses on the west coast of Vancouver Island, British Columbia, Canada, the proposed thesis: 1) Examines and assembles the historic erosive water level regime and attempts to draw links to observed high magnitude storm events that have occurred in the Tofino-Ucluelet region (Wickaninnish Bay); and 2) Explores the geomorphic response of local shorelines by examining the geomorphology and historical evolution of a foredune-riverine-backshore bluff complex. Despite rapid shoreline progradation, foredune erosion occurs locally with a recurrence interval of ~1.53 yrs. followed by rapid rebuilding, often in the presence of large woody debris and rapidly colonizing vegetation, which drives a longer-term trend of shoreline progradation. This process is complicated locally, however, by the influence of local geological control (bedrock headlands) and backshore rivers, such as Sandhill Creek, which alter spatial-temporal patterns of both intertidal and supratidal erosion and deposition. This work is necessary to understand mechanisms responsible for erosive water levels and the process interaction responsible for subsequent coastal rebuilding following erosive periods. / Graduate / 0368 / derek.heathfield@gmail.com

Ensemble simulations of smoke aerosol radiative effects with a regional climate model in the Amazon has been conducted to investigate the radiative effects of aerosols on clouds, rainfall, and circulation from dry to wet season. The results of the ensemble simulations suggest that the radiative effect of the smoke aerosols can reduce daytime surface radiative and sensible fluxes, the depth and instability of the planetary boundary layer (PBL), consequently the clouds in the lower troposphere in early afternoon in the smoke center, where the aerosols optical depth, AOD, exceeds 0.3. The aerosol radiative forcing also appears to weaken moisture transport into the smoke center and increase moisture transport and cloudiness in the region upwind to the smoke center, namely, the northern Amazon. Anomalous wind convergence over the equatorial western Amazon occurs to compensate the anomalous wind divergence in the southern Amazon, leading to an increase of both clouds and rainfall in that region. The increased atmospheric thermodynamic stability in Southern Amazonia also appears to block synoptic cyclonic activities propagated from extratropical South America, leading to an increased synoptic cyclonic activities and rainfall in southern Brazil, Paraguay and northern Argentina. Evidently, the dynamic response of the monsoon circulation plays a major role in determining the pattern of rainfall change induced by the radiative effect of the aerosols.

Le carbone-suie, ou “black carbon” (BC), contribue au réchauffement climatique avec un forçage positif de l’ordre de +1.1 W m-2 dont l’incertitude reste haute (de l’ordre de 90%). Ce forçage s’effectue à travers l’interaction aérosol-radiation et l’interaction aérosols-nuage. Ces deux mécanismes sont affectés par le degré de mélange des particules du BC avec divers matériaux non-réfractaires et non-absorbants. Cependant, les estimations du forçage radiatif considèrent rarement les effets du mélange interne. Par ailleurs le rôle du BC comme noyau glaçogène qui influence l’interaction aérosol-nuage est largement inconnu. L’objectif de cette thèse est de mieux comprendre les mécanismes par lesquels le degré de mélange interne du BC influence la variabilité des propriétés optiques du BC et les propriétés d’activation des noyaux glaçogènes contenant du BC.Dans le premier chapitre de cette thèse, nous avons exploré la variabilité spatiale et saisonnière du coefficient d’absorption massique -mass absorption cross-section (MAC)- dans l’atmosphère en Europe. Les valeurs de MAC sont déterminées à partir de concentrations de carbone élémentaire et de coefficients d’absorption observée à différentes stations d’observation européenne du réseau ACTRIS (Aerosol, Cloud and Trace gases Research InfraStructure). Les résultats montrent une faible variabilité spatiale du MAC avec une moyenne de 10 ± 2.5 m2 g-1 à 637 nm de longueur d’onde qui peut être considérée comme représentative du BC en Europe. Le cycle saisonnier du MAC est probablement lié à la composition chimique de l’aérosol et son état de mélange, qui provoque une augmentation du MAC.Dans le second chapitre on s’est intéressé au lien entre l’absorption du BC et son état de mélange après transport sur longue-distance. Ce travail se base sur des mesures effectuées dans le cadre du projet CLIMSLIP (CLimate IMpact of Short-Lived Pollutants and methane in the Arctic). Une campagne de mesure a été conduite sur la station de recherche Zeppelin au Svalbard, Norvège en Avril 2012. Les données acquises avec un Single Particle Soot Photometer (SP2) révélaient que le BC est généralement présent en mélange interne dont l’épaisseur moyenne de la couche superficielle de matériel non-absorbant est de 47 nm pour des particules de BC de diamètre compris entre 170 et 280 nm. Ce mélange interne conduit à une augmentation d’absorption de 46%. Elle entraîne cependant une diminution relativement faible de l’albédo de simple diffusion, de l’ordre de 1%.Enfin, la capacité du BC à agir comme noyaux glaçogène pour la formation de cristaux de glace a été étudiée sur le site de haute altitude du Jungfraujoch (Suisse) dans le cadre du “cloud and aerosol characterization experiment” (CLACE) en 2013. Les différents éléments du nuage étaient séparé à partir d’une prise d’entrée type ice-CVI connectée au SP2. Ce dispositif permet de sélectionner uniquement les cristaux de glace et quantifier la fraction de BC activée. Une réduction de la présence de BC dans les résidus de glace a été observée. Des mesures de l’épaisseur de la couche de mélange interne des particules contentant du BC ont montré que les résidus de cristaux de glace présentaient des enrobages bien plus épais comparée à l’aérosol total.Les résultats obtenus au cours de ce travail ont permis de mieux comprendre l’impact du degré de mélange interne sur les propriétés optiques du BC et sur son rôle dans la formation de cristaux de glace. Les propriétés optiques du BC évoluent en fonction de la saison, tandis que la formation d’une couche superficielle amplifie sa capacité d’absorption du rayonnement solaire. De plus, cette étude souligne l’importance du vieillissement atmosphérique du BC sur sa capacité à servir de noyau de nucléation de la glace. Enfin, il fournit une avancée au sujet des propriétés sensibles mesurées dans l’atmosphère avec des techniques innovantes qui permettront la simulation plus précise du forçage radiatif. / Black carbon (BC) induces a warming effect (RFBC = +1.1 W m-2 ± 90%) through two main pathways: aerosol-radiation interaction (RFari) and aerosol-cloud interaction (RFaci). Both BC-radiation and BC-cloud interaction are affected by the mixing of black carbon with other non-refractory and non-absorbing matter present in the atmosphere. An estimation of the global radiative forcing of BC rarely accounts for internal mixing of BC while the net global cloud radiative forcing is sensitive to assumptions in the initiation of cloud glaciation, which is mostly unknown for black carbon particles. Within this thesis we investigated the variability of the light absorbing properties of black carbon, the mixing of black carbon, and the impact on light absorption and ice activation.In the first part of this thesis we investigated the spatial and seasonal variability of the mass absorption cross section (MAC) over Europe. MAC values were determined from ambient observations of elemental carbon mass concentrations (mEC) and absorption coefficients (σap). The data had been acquired during several years at different background ACTRIS supersites spread over Europe. Site specific MAC values were found to be spatially homogeneous, suggesting that the overall MAC average 9.5 ± 1.9 m2 g-1 at a wavelength of 637 nm might be representative of BC at European background locations. The MAC values showed a distinct seasonal cycle at every station. This seasonality might be related to chemical composition and aging. We observed that the MAC value has a linear and positive proportionality with the non-absorbing matter mass fraction.The second part of the work focuses on the coating acquisition of BC and the induced absorption enhancement after long-range transport. Within the CLIMSLIP (climate impact of short-lived pollutants and methane in the Arctic) project field experiments were conducted at the Zeppelin research site in Svalbard, Norway, during the Arctic spring. SP2 data were used to characterize the BC size distribution and mixing. BC containing particles having a core diameter between 170 and 280 nm were found to have a median coating thickness of 47 nm. The relationship between coating thickness and BC absorption was simulated. The observed coating thickness enhanced the mass absorption cross section by 46%, which led to a decrease of less than 1% in the single scattering albedo.In the final part of this work, the role of black carbon as ice nuclei in mixed phase clouds was investigated at the high elevation measuring site Jungfraujoch (Switzerland) during the cloud and aerosol characterization experiment (CLACE) held in 2013. The ice-CVI inlet and a single particle soot photometer were used to select and quantify the ice activated BC particles. According to the observations, BC containing particles were depleted in the ice residuals. The activation efficiency showed a size dependency, with larger BC containing particles being activated more efficiently compared to smaller ones. Activated BC cores having a diameter between 170 and 240 nm showed a larger coating thickness (median = 53 nm) compared to the total aerosol (median = 16 nm).The results obtained in this thesis shed new light on the effect of the mixing state on the optical properties and cloud activation of black carbon particles. Absorbing properties of BC showed a distinct seasonal pattern, while aging was found to consistently increase its absorption behavior. However, black carbon was found not to act as ice nuclei in low tropospheric mixed-phase clouds, where the coating thickness might play a role in the activation efficiency. This work provides freshly determined physical properties derived from ambient observations that will improve the accuracy of future aerosol and cloud radiative forcing estimations.

No description available.

Title: Structure of equality sets Author: Jana Hadravová Department: Department of Algebra Supervisor: doc. Mgr. Štěpán Holub, Ph.D., Dept. of Algebra Abstract: Binary equality set of two morphisms g, h : ⌃⇤ ! A⇤ is a set of all words w over two-letter alphabet ⌃ satisfying g(w) = h(w). Elements of this set are called binary equality words. One of the important results of research on binary equality sets is the proof of the fact that each binary equality set is generated by at most two words provided that both morphisms g and h are non-periodic. Moreover, if a binary equality set is generated by exactly two words, then the structure of both generators, and therefore of the whole set, is uniquely given. This work presents the results of our research on the structure of binary equality sets with a single generator. Importantly, these generators can be decomposed into simpler structures. Generators which can not be further decomposed are called simple equality words. First part of the presented work describes the structure of simple equality words and introduces their detailed classification. The main result of the first part is a precise characterisation of su ciently large simple equality words. In the second part, the work describes the iterative process which transforms a general generator of a binary...

This thesis describes an experimental investigation of the response of lean turbulent swirling flames with different degrees of premixedness (i.e. different mixture patterns) to acoustic forcing using the same burner configuration and varying only the fuel injection strategy. Special emphasis was placed on the amplitude dependence of their response. Also, the behaviour of self-excited fully premixed flames was examined. kHz OH* chemiluminescence was used to study qualitatively the heat release response of the flames, while kHz OH Planar Laser Induced Fluorescence (PLIF) was employed to understand the response of the flame structure and the behaviour of the various parts of the flame. The Proper Orthogonal Decomposition (POD) method was used to extract the dominant structures of the flame and their periodicity. In the first part of the thesis, self-excited oscillations were induced by extending the length of the duct downstream of the bluff body. It was found that the longer the duct length and the higher the equivalence ratio, the stronger the self-excited oscillations were, with the effect of duct length being much stronger. The dominant frequencies of the system were found to increase with equivalence ratio and bulk velocity and decrease with duct length. For some conditions, three simultaneous periodic motions were observed, where the third motion oscillated at a frequency equal to the difference of the other two frequencies. A novel application of the POD method was proposed to estimate the convection velocity from the most dominant reaction zone structures detected by OH* chemiluminescence imaging. For a range of conditions, the convection velocity was found to be in the range of 1.4-1.7 bulk flow velocities at the inlet of the combustor. In the second part, the response of fully premixed, non-premixed with radial fuel injection (NPR) and axial fuel injection (NPA) flames was investigated and compared. All systems exhibited a nonlinear response to acoustic forcing. The highest response was observed by the NPR flame, followed by the fully premixed and the non-premixed with axial fuel injection flame. The proximity of forced flames to blow-off was found to be critical in their heat release response, as close to blow-off the flame response was significantly lower than that farther from blow-off. In the NPR and NPA systems, it was shown that the acoustic forcing reduced the stability of the flame and the stability decreased with the increase in forcing amplitude. In the fully premixed system, the flame area modulations constituted an important mechanism of the system, while in the NPR system both flame area and equivalence ratio modulations were important mechanisms of the heat release modulations. The quantification of the local response of the various parts of the flame at the forcing frequency showed that the ratio RL (OH fluctuation at 160 Hz to the total variance of OH) was greater in the inner shear layer region than in the other parts in the case of NPR and NPA flames. In fully premixed flames, greater RL values were observed in large regions on the downstream side of the flame than those in the ISL region close to the bluff body. The ratio of the convection velocity to the bulk velocity was estimated to be 0.54 for the NPR flame, while it was found to be unity for the respective fully premixed flame. In the last part of the thesis, the response of ethanol spray flames to acoustic oscillations was investigated. The nonlinear response was very low, which was reduced closer to blow-off. The ratio RL was the highest in the spray outer cone region, downstream of the annular air passage, while RL values were very low in the inner cone region, downstream of the bluff body. Unlike NPR and fully premixed flames, in case of spray and NPA systems, it was found that forcing did not affect greatly the flame structure. The understanding of the nonlinear response of flames with different degrees of premixedness in a configuration relevant to industrial systems contributes to the development of reliable flame response models and lean-burn devices, because the degree of premixedness affects greatly the flame response. Also, the understanding of the behaviour of forced spray flames is of great interest for industrial applications, contributing to the development of thermoacoustic models for liquid fuelled combustors. Finally, the estimation of the convection velocity is of importance in the modelling of self-excited flames and flame response models, since the convection velocity affects the flame response significantly.

Estimativas de erro são estabelecidas em termos do número de Rossby para a aproximação de Galerkin não linear nas soluções do modelo atmosférico balanceado de Lorenz com massa forçante. Desse modo a aproximação espectral da aproximação de Galerkin não linear é ligada ao número de Rossby. / Error estimates are established in terms of the Rossby number for a nonlinear Galerkin approximation to the solutions of the balanced atmosphere model of Lorenz with mass forcing. Thereby, the approximation spectral dimension of the nonlinear Galerkin approximation is linked to the Rossby number.