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  • About
  • The Global ETD Search service is a free service for researchers to find electronic theses and dissertations. This service is provided by the Networked Digital Library of Theses and Dissertations.
    Our metadata is collected from universities around the world. If you manage a university/consortium/country archive and want to be added, details can be found on the NDLTD website.
481

Optical Micromanipulation Techniques Combined with Microspectroscopic Methods / Optical Micromanipulation Techniques Combined with Microspectroscopic Methods

Pilát, Zdeněk January 2015 (has links)
Předložená dizertační práce se zabývá kombinací optických mikromanipulací s mikrospektroskopickými metodami. Využili jsme laserovou pinzetu pro transport a třídění živých mikroorganismů, například jednobuněčných řas, či kvasinek. Ramanovskou spektroskopií jsme analyzovali chemické složení jednotlivých buněk a tyto informace jsme využili k automatické selekci buněk s vybranými vlastnostmi. Zkombinovali jsme pulsní amplitudově modulovanou fluorescenční mikrospektroskopii, optické mikromanipulace a jiné techniky ke zmapování stresové odpovědi opticky zachycených buněk při různých časech působení, vlnových délkách a intenzitách chytacího laseru. Vyrobili jsme různé typy mikrofluidních čipů a zkonstruovali jsme Ramanovu pinzetu pro třídění mikro-objektů, především živých buněk, v mikrofluidním prostředí.
482

Design of a Differential Cross-Coupled Power LC Oscillator with ASK Modulation

Sarker, Sanjay January 2023 (has links)
Rapid growth in the field of communications industry has led to newer opportunities and challenges in the design of CMOS based monolithic integrated circuits. ASK modulators are a class of digital modulators which are known for their relative simplicity of implementation for low cost applications in the industrial and biomedical domains. This thesis presents a LC-based CMOS Amplitude Shift Keying (ASK) modulator scheme which demonstrates promising capability for radio frequency designs. This work describes the design and implementation of differential cross-coupled NMOS only LC power oscillator with ASK modulation to operate at 2.4 GHz frequency. In this work, 65nm CMOS process technology has been used for implementation. The work mainly focused on system parameters such as oscillation frequency, output signal power, power consumption and phase noise. The LC tank was created with a centre-tap on-chip differential spiral inductor and a Metal Insulator Metal (MIM) capacitor. The method of a current mirror with switching technique is employed for biasing the LC oscillator as well as ASK modulation output. The oscillator circuit has been optimised by using a simulation based approach to study the design and measurements to gain a greater insight into the performance of the ASK modulator. An output signal power of -1.59dBm at 2.30 GHz with a phase noise of -115.39dBc/Hz@1MHz and a power consumption of 5.92mW has been achieved at the layout level. Optimal ASK modulated output performance has been obtained for the data rate of up to around 40Mbits/s. In this thesis, simulation results have been presented for both the schematic and the layout levels.
483

[en] AMPLITUDE ANALYSIS OF THE DS+ TO K-K+K+ DECAY USING THE LHCB RUN 2 DATA / [pt] ANÁLISE DE AMPLITUDES DO DECAIMENTO DS+ EM K−K+K+ USANDO DADOS DO RUN 2 DO LHCB

GUSTAVO ALEJANDRO LOACHAMIN ORDONEZ 15 May 2023 (has links)
[pt] Apesar de ser considerada uma teoria de sucesso no campo das partículas e interações fundamentais, o Modelo Padrão é considerado incompleto porque ainda deixa uma série de questões em aberto. Para abordar algumas delas, é necessário estudar processos tais como decaimento de partículas. Em particular, os decaimentos de hádrons pesados, como os mésons D e B, podem ser sensíveis à física além do Modelo Padrão, como novas fontes de violação de carga-paridade e novas interações. No entanto, com massas na faixa de poucos GeV, onde os cálculos perturbativos da cromodinâmica quântica são limitados, modelos fenomenológicos são necessários para descrever seus decaimentos hadrônicos. Nesta dissertação, um estudo da dinâmica de decaimento de 3 corpos do canal Ds+ em K−K+K+ é apresentado pela primeira vez e utiliza duas abordagens fenomenológicas para descrever a amplitude do decaimento: o Modelo Isobárico e a chamada Quasi-Model Independent Partial Wave Analysis (QMIPWA). As amostras utilizadas correspondem aos dados coletados na run 2 do experimento LHCb (entre os anos 2016-2018) com colisões prótonpróton a uma energia de centro de massa de 13 TeV. A análise é realizada após um processo de seleção para reduzir o background, levando a uma amostra final com cerca de 100 mil decaimentos. Para realizar a análise de amplitudes no Dalitz plot do decaimento, o background remanescente e a eficiência ao longo do gráfico de Dalitz são parametrizados. No caso em que a amplitude de decaimento é descrita pelo Modelo Isobárico, os resultados obtidos mostram uma dominância da ressonância phi(1020) e uma composição de ressonâncias escalares, f0(980) como a mais clara, sendo formada como estados intermediários, e uma pequena mas não desprezível contribuição das ressonâncias de spin-2. O Modelo Isobárico oferece uma descrição qualitativa da dinâmica de decaimento, mas não fornece um ajuste de boa qualidade, mesmo quando uma variedade de possíveis estados intermediários são adicionados ao modelo de amplitude. Por outro lado, o QMIPWA como ferramenta para descrever o setor escalar revelou-se difícil para a região de massa K−K+ acima de 1.3 GeV e sensível às ressonâncias de spin mais alto adicionadas ao modelo, tornando difícil e menos confiável a interpretação dos resultados obtidos. Ainda com as limitações encontradas nos dois modelos, a análise apresentada aqui representa um passo importante para o entendimento da dinâmica deste decaimento, abrindo caminho para estudos com maior estatística no run 3 do LHCb. / [en] Despite of being considered a successful theory in the field of fundamental particles and interactions, the Standard Model is considered incomplete because it still leaves a number of open questions. In order to address some of these, it is necessary to study physical processes such as particle decays. In particular, the decays of heavy hadrons such as D and B mesons can be sensitive to physics beyond the Standard Model, such as new sources of charge-parity violation and new interactions. Nevertheless, at masses at the few GeV range, where perturbative calculations of quantum chromodynamics are limited, phenomenological models are needed to describe their hadronic decays. In this dissertation, a study of the 3-body decay dynamics of the Ds+ to K-K+K+ channel is presented for the first time and uses two phenomenological approaches to describe the decay amplitude: the Isobar Model and the Quasi-Model Independent Partial Wave Analysis (QMIPWA). The samples used corresponds to the data collected in Run 2 of the LHCb experiment (between the years 2016-2018) with proton-proton collisions at a center-of-mass energy of 13 TeV. The analysis is performed after a selection process to reduce background, leading to a final sample of about 100 thousand decays. To perform the amplitude analysis fit to the Dalitz plot of the decay, the remaining background and the efficiency across the Dalitz plot are parametrized. In the case of the Isobar Model, the results obtained show a dominance of the phi(1020) resonance and a composition of scalar resonances, f0(980) as the most clear one, being formed as intermediate states, and a small but not negligible contribution of spin-2 resonances. The Isobar Model offers a qualitative description of the decay dynamics but does not provide a good quality fit, even when a variety of possible intermediate states are added to the amplitude model. On the other hand, the QMIPWA as a tool to describe the scalar sector revealed itself difficult for the region of K−K+ mass above 1.3 GeV and sensitive to the higher-spin resonances added to the model, making it difficult and less reliable to interpret the results obtained. Even with the limitations found through both models, the analysis presented here represent an important step towards the understanding of the dynamics of this decay, opening the path to further studies with higher statistics in run 3 of LHCb.
484

Seismic and Well Log Attribute Analysis of the Jurassic Entrada/Curtis Interval Within the North Hill Creek 3D Seismic Survey, Uinta Basin, Utah, A Case History

ONeal, Ryan J. 18 July 2007 (has links) (PDF)
3D seismic attribute analysis of the Jurassic Entrada/Curtis interval within the North Hill Creek (NHC) survey has been useful in delineating reservoir quality eolian-influenced dune complexes. Amplitude, average reflection strength and spectral decomposition appear to be most useful in locating reservoir quality dune complexes, outlining their geometry and possibly displaying lateral changes in thickness. Cross sectional views displaying toplap features likely indicate an unconformity between Entrada clinoforms below and Curtis planar beds above. This relationship may aid the explorationist in discovering this important seismic interval. Seismic and well log attribute values were cross plotted and have revealed associations between these data. Cross plots are accompanied by regression lines and R2 values which support our interpretations. Although reservoir quality dune complexes may be delineated, the Entrada/Curtis play appears to be mainly structural. The best producing wells in the survey are associated with structural or stratigraphic relief and the thickest Entrada/Curtis intervals. Structural and stratigraphic traps are not always associated with laterally extensive dune complexes. Time structure maps as well as isochron maps have proven useful in delineating the thickest and/or gas prone portions of the Entrada/Curtis interval as well as areas with structural and stratigraphic relief. We have observed that the zones of best production are associated with low gamma ray (40-60 API) values. These low values are associated with zones of high amplitude. Thus, max peak amplitude as a seismic attribute may delineate areas of higher sand content (i.e. dune complexes) whereas zones of low amplitude may represent areas of lower sand content (i.e. muddier interdune or tidal flat facies). Lack of significant average porosity does not seem to be related to a lack of production. In fact, the best producing wells have been drilled in Entrada/Curtis intervals where average porosity is near 4 %. There are however zones within the upper portion of the Entrada/Curtis that are 40 ft. (12.2 m) thick and have porosities between 14% and 20%. By combining derived attribute maps with observed cross plot relationships, it appears that the best producing intervals within the Entrada/Curtis are those associated with high amplitudes, API values from 40-60 and structural relief.
485

Behavior of a Full-Scale Pile Cap with Loosely and Densely Compacted Clean Sand Backfill under Cyclic and Dynamic Loadings

Cummins, Colin Reuben 16 March 2009 (has links) (PDF)
A series of lateral load tests were performed on a full-scale pile cap with three different backfill conditions, namely: with no backfill present, with densely compacted clean sand in place, and with loosely compacted clean sand in place. In addition to being displaced under a static loading, the pile cap was subjected to low frequency, small displacement loading cycles from load actuators and higher frequency, small displacement, dynamic loading cycles from an eccentric mass shaker. The passive earth pressure from the backfill was found to significantly increase the load capacity of the pile cap. At a displacement of about 46 mm, the loosely and densely compacted backfills increased the total resistance of the pile cap otherwise without backfill by 50% and 245%, respectively. The maximum passive earth pressure for the densely compacted backfill occurred at a displacement of approximately 50 mm, which corresponds to a displacement to pile cap height ratio of 0.03. Contrastingly passive earth pressure for the loosely compacted backfill occurred at a displacement of approximately 40 mm. Under low and high frequency cyclic loadings, the stiffness of the pile cap system increased with the presence of the backfill material. The loosely compacted backfill generally provided double the stiffness of the no backfill case. The densely compacted backfill generally provided double the stiffness of the loosely compacted sand, thus quadrupling the stiffness of the pile cap relative to the case with no backfill present. Under low frequency cyclic loadings, the damping ratio of the pile cap system decreased with cap displacement and with increasing stiffness of backfill material. After about 20 mm of pile cap displacement, the average damping ratio was about 18% with the looser backfill and about 24% for the denser backfill. Under higher frequency cyclic loadings, the damping ratio of the pile cap system was quite variable and appeared to vary with frequency. Damping ratios appear to peak in the vicinity of the natural frequency of the pile cap system for each backfill condition. On the whole, damping ratios tend to range between 10 and 30%, with an average of about 20% for the range of frequencies and displacement amplitudes occurring during the tests. The similar amount of damping for different ranges of frequency suggests that dynamic loadings do not appreciably increase the apparent resistance of the pile cap relative to slowly applied cyclic loadings.
486

The Effectiveness Of Data Codes And Hardware Selection To Mitigate Scintillation Effects On Free Space Optical Data Transmission

Stein, Keith 01 January 2006 (has links)
The design of an optical communication link must plan for the random effects of atmospheric turbulence. This study analyses data from an experiment which transmitted from a laser located 8 meters above ground over a 13 Km range to coherent detection devices approximately 162 meters above ground. The effects of a fading and surging beam wave were considered in regards to code techniques for error correction, amplitude modulation and hardware architecture schemes. This study simulated the use of arrays and large apertures for the receiving devices, and compared the resultant scintillation index with the theoretical calculations.
487

First Order Self-Oscillating Class-D Circuit with Triangular Wave Injection

Carroll, Matthew J 01 June 2021 (has links) (PDF)
An investigation into performance improvements to the modulator stage of a class-D amplifier is conducted in this thesis. Two of the standard topologies, namely class-D open-loop pulse-width modulation (PWM), and the improved self-oscillating feedback system are benchmarked against a topology which includes both a hysteretic comparator in a feedback loop and triangle wave injection. Circuit performance is analyzed by comparing how the triangle injection circuit handles known issues with open-loop and self-oscillating circuits. Using this analysis, it is shown that the triangle injection topology offers an improved power supply rejection ratio relative to open-loop PWM and reduces distortion generated by frequency modulation characteristic of the self-oscillating topology.
488

A Study of Open Orbits In Gallium, Cadmium, Zinc and Copper By An Induced Torque Method

Cook, James Robert 10 1900 (has links)
<p> The theoretical treatment of the induced torque problem is discussed, and equations describing the functional form of the torque amplitude are derived on the basis of a model calculation valid in the high field limit. This functional form is applied to a detailed interpretation of the open orbit structure in gallium, cadmium, zinc and copper. </p> <p> An investigation of the open orbit structure in gallium at l.4°K using this technique has yielded direct information on the connectivity of the sixth-band hole surface. This surface supports a k(c)-trajectory for all field directions in the ab plane, except within 0.1° of the a-axis. A k(a)-trajectory of lower conductivity is reported over a 10° range of field direction centred (32°±2°) from the b-axis in the be plane. These data, in addition to the highly anisotropic amplitude and field dependence of the k(c) -trajectory, require that this surface contact the Brillouin zone boundary at both the k(a) -and k(c) -faces. The present data are compared with available models of the sixth band hole surface, and are found to be in excellent agreement with the predictions of recent pseudopotential calculations . The possibility of magnetic breakdown in the k(c)-trajectory for B|| b-axis is discussed. Finally, a non-linear frequency dependence, and an anisotropic non-quadratic field dependence are understood to occur through the long mean free path and short skin depth parameters in gallium at l.4°K. </p> <p> In cadmium, the induced torque amplitude due to the [0001]-open trajectory tends to saturation at high field intensities for all observation directions. This effect is attributed to magnetic breakdown between the first-and secondhand hole surfaces through the spin·-orbit interaction energy 'gap near the H-symmetry point in the AHL plane. This magnetic breakdown effect is analyzed on the basis of a linear chain model and the theoretical curves of Falicov and Sievert. Detailed analysis indicates the possibility of two separate breakdown probabilities across the HL and HA gaps; for <1010> directions , breakdown fields of 10.8 k0e and (as low as) 0.72 k0e are indicated . A similar range of breakdown fields is indicated for all field directions in the (0001) plane. </p> <p> In zinc, the induced torque technique is used to investigate magnetic breakdown effects in the [0001]-trajectory for specific field directions in the basa l plane. These effects are attributed to the onset of partial breakdown between the monster and cap surfaces near the H-symrnetry points, for field intensities above 16 kOe. The linear chain model is shown to be an inappropriate description of breakdown effects in zinc. An onset field of 16 kOe for <1120> is determined; no breakdown is observed along <lOIO> below 20 kOe. In addition, magnetic breakdown effects occurring in the basal orbits of zinc were investigated. The general monotonic rise in torque amplitude with field intensities is fitted to the theoretical expressions of Falicov, Pippard, and Sievert. The giant quantum oscillations arising through coherence-effect modulation of the breakdown probability are shown consistent with earlier data. </p> <p> The technique is applied to a general survey of the various types of open orbits existing in copper, and the general applicability of the sample torque equations to both compensated and uncompensated metals is demonstrated. </p> / Thesis / Doctor of Philosophy (PhD)
489

Asymptotic enumeration via singularity analysis

Lladser, Manuel Eugenio 15 October 2003 (has links)
No description available.
490

[pt] MODELAGEM DE GOTAS DISPERSAS EM ESCOAMENTO ANULAR VERTICAL / [en] MODELLING OF DISPERSED DROPLETS IN VERTICAL ANNULAR TWO-PHASE FLOW

JOAO GABRIEL CARVALHO DE SIQUEIRA 30 April 2020 (has links)
[pt] O escoamento anular é caracterizado por um núcleo gasoso fluindo a alta velocidade com um filme líquido no seu entorno, molhando a parede do duto. A presença de gotículas líquidas no núcleo gasoso resulta em impacto relevante em características do escoamento anular, como gradiente de pressão e propriedades das ondas presentes no filme líquido. A formação de gotículas se dá usualmente na crista das ondas de perturbação presentes na interface líquido-gás. No presente trabalho, é realizado um estudo do regime anular com presença de gotículas em tubulações verticais utilizando o Modelo de Dois Fluidos unidimensional. Um modelo de transferência de massa das gotículas é desenvolvido e acoplado ao modelo de Dois Fluidos. O modelo resultante permite capturar a evolução automática da interface gás-líquido e a formação de ondas de filme líquido e sua influência no desprendimento e deposição de gotículas. Analisa-se o desempenho de três modelos de entranhamento de gotículas disponíveis na literatura, além de um modelo de deposição de gotículas. Considerando que gotículas são criadas por cisalhamento nas cristas das ondas de perturbação, modificações dos modelos são propostas com a finalidade de melhor capturar a influência das ondas do filme líquido nos processos de entranhamento e deposição de gotículas. Parâmetros do escoamento como gradiente de pressão, espessura do filme do líquido e variáveis relacionadas com as ondas interfaciais são avaliados, mostrando boa concordância com dados experimentais disponíveis na literatura. / [en] Annular flow is characterized by a high velocity gas core flow, with a thin liquid film around it, wetting the pipe wall. The presence of liquid droplets in the gas core has relevant impact on annular flow characteristics, such as pressure drop and liquid film wave properties. Droplets are usually created by shear at disturbance wave crests, along the gas-liquid interface. At the present work, vertical annular flow with droplet entrainment is studied using the 1-D Two-Fluid model. A droplet mass transfer model is developed and coupled to the Two-Fluid model. The resulting model allows capturing the automatic evolution of the gas-liquid interface, liquid film wave formation and the waves influence on droplet entrainment and deposition. A performance analysis in carried out for three droplet entrainment models available in literature, as well as one deposition model. Taking into account that droplets are created by disturbance wave crest shearing, model modifications are proposed, aiming to better capture the influence of liquid film waves on droplet entrainment and deposition mechanisms. Flow parameters such as pressure drop, film thickness and wave features are evaluated, showing good agreement with experimental data found in literature.

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