O trabalho apresentado nesta dissertação consiste do estudo do comportamento direcional de um veículo comercial de 2 eixos, classificando-o quanto a sua estabilidade (Oversteer, Understeer ou Neutral Steer) e predizendo em que condições sua instabilidade torna-se crítica. para esta finalidade, o veículo foi modelado desenvolvendo uma trajetória curvilínea de raio constante em situação de regime permanente e uma rotina de cálculos representa sua dinâmica lateral. O recurso computacional utilizado (software Excel) foi propositadamente escolhido tendo como premissa ser o mais simples possível, para que os custos e tempo envolvidos fossem mínimos. Foram realizadas algumas medições com o veículo em questão e, levando-se em conta todas as simplificações implementadas, os resultados práticos e teóricos demonstraram correlação satisfatória. Desta maneira, então, pode-se dizer que o instrumento desenvolvido neste trabalho pode ser aplicado como um recurso valioso durante a fase inicial de conceituação da suspensão de um veículo de 2 eixos, principalmente tratando-se de uma avaliação comparativa com veículos semelhantes já testados. / The work presented consists of a 2 axles light truck directional behavior evaluation, where computational resources applied are very simple and easy hand (software excel). Steady state cornering concept was used to get its stability classification (Oversteer, Understeer or Neutral Steer) and show in which moment its behavior become unstable. Experimental measurements took place and the practical (measured) and theoretical (came from the developed model) results showed theirselves satisfactory, considering all the simplifications. Thus, this procedure might be useful during a two axle light truck suspension development, ultimately if is adopted to compare with another one already known. Costs and time are saved in this way.

Dissertação (Mestrado em Engenharia Mecânica) - Centro Universitário FEI, São Bernardo do Campo, 2016.

This study explores the reactions and related species of NOx pollutants in methane flames in order to understand their production and consumption during the combustion process. To do this, several analytical simulations were run to explore the behavior of nitrogen species in the pre-flame, post- flame, and reaction layer regions. The results were then analyzed in order to identify all "steady-state" species in the flame as well as the determine all the unnecessary reactions and species that are not required to meet a defined accuracy. The reductions were then applied and proven to be viable.

Various directional comparison bus protection methods including widely used superimposed directional element method need to have both voltages and currents from all feeders connected to the zone of protection to find the direction of current for detecting a bus fault or a line fault. The purpose of the thesis is to present a new technique for directional comparison bus protection to discriminate a bus fault from line fault and normal condition. The new technique, which is implementing superimposed directional element method to modify partial operating current characteristics (POC) method to superimposed POC (SPOC) method, does not use voltages from feeders, hence capacitor voltage transformers (CVTs) are no longer needed in the zone of protection. The proposed technique was implemented in 4-bus and IEEE 14-bus test system and was tested using different fault cases including CT saturation and high impedance fault. The proposed technique, SPOC method was compared with POC method with both methods implemented in same test systems and tested with same fault cases. The results show that the proposed technique is successful to detect bus faults with high accuracy and high speed.

In this thesis, we will study bio-mathematics. We will introduce differential equations, biological applications, and simulations with emphasis in molecular events. One of the first courses of action is to introduce and construct a mathematical model of our biological element. The biological element of study is the Hepatitis C virus. The idea in creating a mathematical model is to approach the biological element in small steps. We will first introduce a block (schematic) diagram of the element, create differential equations that define the diagram, convert the dimensional equations to non-dimensional equations, reduce the number of parameters, identify the important parameters, and analyze the results. These results will tell us which variables must be adjusted to prevent the Hepatitis C virus from becoming chronic.

Cette thèse, à la fois numérique et expérimentale, porte sur l’étude du transfert de chaleur par convection naturelle qui apparait au sein d’une cavité hémisphérique en régime stationnaire. L’enceinte est remplie d’eau ou de nanofluide de type eau / ZnO. La fraction volumique varie entre 0 (eau pure) et 10%. La coupole de la cavité est maintenue à température froide. Ce travail s’applique au domaine de l’ingénierie électronique et plus particulièrement au refroidissement des composants actifs de différentes formes. Trois géométries de sources de chaleur sont étudiées : la première est plane et circulaire (disque) et les suivantes, centrées sur le disque, de même surface d’échange, sont cubique et hémisphérique. L’angle d’inclinaison du disque varie entre 0 (coupole orientée vers le haut) et 180° (coupole orientée vers le bas) par rapport au plan horizontal. Les sources de chaleur génèrent des puissances qui conduisent à des Rayleigh importants. L’approche numérique est effectuée à l’aide de la méthode des volumes finis basée sur l’algorithme SIMPLE et un modèle monophasique. Pour chaque source active, le transfert de chaleur convectif est analysé et quantifié par l’intermédiaire d’une corrélation du type Nusselt-Rayleigh-Prandtl-angle d’inclinaison. D’un point de vue expérimental, la fabrication des sources de chaleur est minutieusement décrite étape par étape et le calcul du coefficient de transfert convectif moyen expérimental est détaillé. La comparaison mesures-corrélations remet en question l’efficacité du nanofluide en termes de refroidissement. / This numerical and experimental thesis deals with natural convective heat transfer that occurs in a hemispherical cavity in steady state. The enclosure is filled with water or ZnO / water nanofluid. The volume fraction varies between 0% (pure water) and 10%. The coupola of the cavity is kept at a cold temperature. This work corresponds to the field of electronics and the cooling of different actives composants. Three active heating sources are studied: the first one is plane and circular (the disc) and the followings, centered on the disc with the same surface, are cubical and hemispherical. The tilted angle varies between 0 (dome facing upwards) and 180° (dome facing downwards) with respect to the horizontal plane. Heat sources generate important heat fluxes leading to high Rayleigh numbers values. Numerical approach is done by means of the volume control method based on the SIMPLE algorithm and using monophasic model. For each active source, the convective heat transfer is analyzed and quantified by means of a correlation of the Nusselt-Rayleig-Prandtl-tilt angle type. Experimentally, the heat sources are built step by step and the average convective heat transfer coefficient is calculated. The comparison measures-correlations questions on the cooling nanofluid’s efficiency.

Dopamine appears to play a critical role in regulating spatial working memory (SWM) in non-human primates, and SWM deficits are observed in patients with Parkinson�s disease and schizophrenia. Unfortunately, the current experimental literature in humans is marred by inconsistent behavioural findings, and there is a void in neuroimaging studies examining dopaminergic manipulation of SWM-related brain activity. The present thesis used a combination of behavioural neurocognitive testing and brain imaging to further examine dopaminergic manipulation of SWM in healthy humans, using two pharmacological challenges: 1) acute tyrosine depletion (TPD) (to acutely deplete tonic dopamine), and 2) D1/D2 receptor activation using the dopamine receptor agonist pergolide (to stimulate dopamine neurotransmission) under conditions of TPD. The effects of TPD on behavioural performance were examined using three SWM tasks: 1) a delayed-recognition task previously impaired by TPD (Experiment 1) and 2) two delayed-response tasks designed to vary only in response requirements (Experiment 2). The findings demonstrated an apparent failure of TPD to impair performance on any of the tasks. Further, the effects of TPD on SWM-related brain activity during a SWM n-back task were examined using regional Cerebral Blood Flow (rCBF) measured by H2 150 Positron Emission Tomography (Experiment 2), and Steady State Visually Evoked Potentials (SSVEP) measured by Steady State Probe Topography (Experiment 4). TPD failed to produce discernable effects on either neural networks (task-related rCBF) or temporal electrophysiological activity (SSVEP) associated with the SWM n-back task. In contrast, D1/D2 receptor stimulation under dopamine depleted conditions impaired performance on both a SWM delayed-response task (Experiment 1) and SWM n-back task (Experiment 2), and resulted in task-related increases in fronto-temporal SSVEP latency (suggestive of increased inhibition) and decreases in parieto-occipital SSVEP amplitude (suggestive of increased activation) during the early delay period of the SWM n-back task (Experiment 4). These changes are consistent with the undisputed role of frontal and parietal regions in n-back task performance, and with previous evidence of dopaminergic modulation of these regions in animals and humans. In summary, TPD did not modulate SWM behavioural performance on four different SWM tasks with differing task demands, and failed to produce measurable changes to either SWM-related neural networks (task-related rCBF) or cortical electrophysiological activity (SSVEP) associated with the SWM n-back task. The implication of these findings, when taken together with previous studies, is that the degree of dopaminergic depletion achieved with TPD may be insufficient to consistently and robustly modulate SWM networks in healthy humans, questioning the utility of TPD as a probe of dopaminergic function. In addition, these findings demonstrate the complexity of stimulating D1/D2 receptors under dopamine depleted conditions, and highlight the critical importance of baseline dopamine levels in influencing the effects of acute dopamine challenge on SWM performance.

<p> </p><p>I denna studie har jämförelse gjorts mellan Interacoustics Eclipse och GSI Audera i samband med Auditory Steady-State Respons (ASSR) mätningar.</p><p>Syftet med studien var att undersöka ASSR som metod, att utvärdera dess tillförlitlighet i jämfö­relse med tonaudiometri för personer med normal hörsel och personer med hörsel­nedsätt­ning. Avsikten var dessutom att undersöka om elektrod­placering­ på örsnibb eller på mastoid påverkade mät­resultatet, försökspersonens upplevelse av instrumen­­t­ens ljudstimuli, om de estimerade ASSR-värdena påverkades av att mättillfället påbörjades eller avslutades med Interacoustics Eclipse samt undersöka tiden för mätningarna.</p><p>En experimentell studie genomfördes. Mätningarna som utfördes var tonaudiometri och ASSR, den senare uppmättes med Interacoustics Eclipse och GSI Audera på (n=20) vuxna med normal hörsel och (n=4) vuxna med hörselnedsättning.</p><p>För personer med normal hörsel påvisades en god överensstämmelse mellan estimerade ASSR-värden och tonaudiometri för Interacoustics Eclipse, något sämre överensstämmelse för GSI Audera. Genomsnittlig mättid för båda instrumenten var ca 40 min. Resultaten visade att elektrodplaceringen inte har någon påverkan på ASSR-värden för Interacoustics Eclipse. Hälften av försökspersonerna upplevde att Interacoustics Eclipse hade ett behagligare ljudstimuli att slappna av till och den andra hälften upplevde GSI Audera som behagligast. De estimerade ASSR-värdena påverkades minimalt beroende på om mättillfället påbörjades eller avslutades med Interacoustics Eclipse.</p><p> </p>

Recent research shows that human auditory steady-state responses (ASSRs) develop a resonance at 40 Hz and the dramatic amplitude increase of the Pb component of the middle latency response (MLR) accounts for the high amplitude of the ASSR at 40 Hz. The first part of this study aimed to investigate the ASSR resonance characteristics as a function of rate in guinea pigs. A study of the grand average of the peak-to-peak and fundamental frequency amplitudes does indeed show a resonance around 40 Hz in guinea pigs. Unlike human ASSRs, this resonance is very broad (26-52 Hz) and flat. The centrally recorded ASSRs are smaller and tend to have resonances at higher rates compared to temporal signals. The second part of the analysis investigated whether the superposition of transient responses can predict the acquired ASSRs at each corresponding rate. This superposition theory is one of two competing theories on the origin of the ASSRs, with the other centering on the induced phase synchronization of brain waves. In order to test the first theory, transient responses were used to create synthetic ASSRs, which were then compared to the acquired ASSRs via correlation coefficient and phasor analysis. For the 40 Hz ASSR, both temporal and central electrode synthesized ASSRs show a correlation coefficient above 0.80. In the comparison at 20 Hz, the correlation coefficient is very high (about 0.9) in the temporal electrode, yet significantly lower (about 0.7) for the central electrode. Furthermore, at 80 Hz, the correlation coefficient is significantly lower in both temporal and central electrodes (about 0.7). At all rates, the correlation coefficients are highest with low jitter sequences. Finally, phasor analysis was also used to test the superposition theory of the generation of the acquired ASSRs at 20, 40, and 80 Hz. Overall, in the temporal recordings at 40 Hz, the superposition of the MLR responses accurately predicted the acquired 40 Hz ASSR as demonstrated by both magnitude and phase analysis. The recordings made in the central electrode only predicted the acquired ASSR in its phases, with significant differences found in magnitude at its main harmonics. Similarly, at 20 and 80 Hz in both temporal and central electrodes, the synthetic ASSRs did not appear to fully predict the acquired ASSRs. Although the phases were successfully predicted, large magnitude variations were observed. As shown by mean prediction error plots, the acquired ASSRs are best predicted by low jitter sequences, followed by low-medium and medium jitter sequences.

In this paper, we identify sufficient conditions for Lyapunov Mean Square Stability (LMSS) of a contention-based network of first-order systems, with state-based schedulers. The stability analysis helps us to choose policies for adapting the scheduler threshold to the delay from the network and scheduler. We show that three scheduling laws can result in LMSS: constant-probability laws and additively increasing or decreasing probability laws. Our results counter the notions that increasing probability scheduling laws alone can guarantee stability of the closed-loop system, or that decreasing probability scheduling laws are required to mitigate congestion in the network. / <p>QC 20130116</p>