This thesis presents how to establish a theoretical model to predict risk of thermal cracking in young concrete when cast on ground or an arbitrary construction. The crack risk in young concrete is determined in two steps: 1) calculation of temperature distribution within newly cast concrete and adjacent structure; 2) calculation of stresses caused by thermal and moisture (due to self-desiccation, if drying shrinkage not included) changes in the analyzed structure. If the stress reaches the tensile strength of the young concrete, one or several cracks will occur. The main focus of this work is how to establish a theoretical model denoted Equivalent Restraint Method model, ERM, and the correlation between ERM models and empirical experiences. A key factor in these kind of calculations is how to model the restraint from any adjacent construction part or adjoining restraining block of any type. The building of a road tunnel and a railway tunnel has been studied to collect temperature measurements and crack patterns from the first object, and temperature and thermal dilation measurements from the second object, respectively. These measurements and observed cracks were compared to the theoretical calculations to determine the level of agreement between empirical and theoretical results. Furthermore, this work describes how to obtain a set of fully tested material parameters at CompLAB (test laboratory at Luleå University of Technology, LTU) suitable to be incorporated into the calculation software used. It is of great importance that the obtained material parameters describe the thermal and mechanical properties of the young concrete accurately, in order to perform reliable crack risk calculations.  Therefore, analysis was performed that show how a variation in the evaluated laboratory tests will affect the obtained parameters and what effects it has on calculated thermal stresses.

Submitted by Fabio Sobreira Campos da Costa (fabio.sobreira@ufpe.br) on 2016-09-19T13:36:37Z No. of bitstreams: 2 license_rdf: 1232 bytes, checksum: 66e71c371cc565284e70f40736c94386 (MD5) COLACAO FINAL.pdf: 6155295 bytes, checksum: 72b54a0d2d74622812225c02c45a9105 (MD5) / Made available in DSpace on 2016-09-19T13:36:37Z (GMT). No. of bitstreams: 2 license_rdf: 1232 bytes, checksum: 66e71c371cc565284e70f40736c94386 (MD5) COLACAO FINAL.pdf: 6155295 bytes, checksum: 72b54a0d2d74622812225c02c45a9105 (MD5) Previous issue date: 2016-02-05 / O anel na derivação gástrica em Y de Roux (DGYR) pode levar a intolerância alimentar, mesmo na ausência de estenose, sendo sua remoção cirúrgica o tratamento habitual. Objetivou-se avaliar a viabilidade, eficácia e segurança da dilatação endoscópica do anel com balão de acalasia – Rigiflex®, bem como a evolução ponderal que se segue ao procedimento. Procedeu-se a um estudo longitudinal retrospectivo, com avaliação de dados coletados prospectivamente. A coorte estudada foi submetida ao procedimento proposto no Hospital das Clínicas da UFPE, entre 2002 e 2011, sendo composta por pacientes advindos de serviços de cirurgia bariátrica, em diferentes regiões do Brasil. Foram incluídos 63 pacientes (45 mulheres e 18 homens), com média de idade de 42,4 anos, com quadro de vômitos pós-alimentares em frequência superior a quatro episódios semanais. A efetividade do método baseou-se na melhora dos sintomas obstrutivos, tendo sido empregadas até quatro sessões. Avaliou-se a evolução do índice de massa corporal (IMC), do percentual de excesso de peso (%EP) e do percentual de perda de excesso de peso (%PEP) da amostra em relação aos períodos pré-operatório, da dilatação e do seguimento tardio. Houve melhora completa da sintomatologia inicial em 59 casos (93,6%) e parcial, em dois casos (3,2%). Houve complicações leves em seis casos (9,6%), todos tratados clinicamente. Após seguimento mediano de 43 meses houve incremento médio no IMC de 2,5 kg/m². A dilatação endoscópica com balão, método minimamente invasivo, mostrou-se viável, segura e eficaz, observando-se pequeno aumento ponderal na avaliação tardia. / The placement of a ring on Roux-en-y gastric bypass (RYGB) can lead to food intolerance, even in the absence of stenosis, and its surgical removal is the usual treatment. The purpose of this retrospective, longitudinal study, which evaluated prospectively collected data, was to evaluate the feasibility, efficacy and safety of endoscopic ring dilation with achalasia balloon - Rigiflex®, as well as the weight gain following the procedure. The patients enrolled in this cohort came from different bariatric services in Brazil and underwent the proposed procedure at Hospital das Clínicas of UFPE, between 2002 and 2011. Sixty three patients (45 women and 18 men) with a mean age of 42.4 years who had more than four post-prandial vomiting episodes per week were included. The effectiveness of the method was based on the improvement in obstructive symptoms, after up to four sessions. The body mass index (BMI), the percentage of excess weight (% EW) and the percentage of excess weight loss (% EWL) of the subjects were evaluated in relation to the preoperative period, the dilation moment and the late follow-up. There was full improvement of the initial symptoms in 59 cases (93.6%) and partial, in two cases (3.2%). Minor complications were observed in six cases (9.6%), which were all treated clinically. After median follow-up of 43 months there was an average BMI increase of 2.5 kg / m². Endoscopic balloon dilation, which is a minimally invasive method, proved to be feasible, safe and effective with a slight weight gain in late evaluation.

Ce travail de thèse porte sur l'étude du comportement de l'interface sol-structure sous sollicitations cycliques. Pour cela, un important programme expérimental à la sonde-pieu, mise en place dans des massifs de sable siliceux en chambre d'étalonnage, a été réalisé. On s'est intéressé, particulièrement, à l'évolution du frottement latéral et de la résistance enpointe à grand nombre de cycles (100 000 cycles), en faisant varier l'état initial du massif (état de densité et contrainte de consolidation) et les paramètres de chargement (amplitude du déplacement cyclique). Lors des essais à déplacement contrôlé, un renforcement important du frottement latéral à grand nombre de cycles a été observé pour les faibles valeurs de résistance en pointe initiale. Ce renforcement n'a quasiment pas été observé avant par les auteurs, car l'accent a été mis sur la phase de dégradation (autour de 1000cycles). Il est attribué à une forte dilatance partiellement empêchée. En revanche, pour les fortes valeurs de résistance en pointe, le renforcement à grand nombre de cycles diminue considérablement. Cette diminution est liée à l'effet des particules fines créées lors du fonçage. Celles-ci jouent le rôle de cimentation/scellement de la surface latérale de la sonde pieu en diminuant sa rugosité. Par ailleurs, des essais à force contrôlée ont été réalisés afin d'étudier la stabilité des pieux. Enfin, des lois empiriques d'évolution du frottement latéral et de la résistance en pointe ont été proposées afin de reproduire les évolutions observées expérimentalement. Ces lois d'évolution ont été intégrées dans un modèle de calcul de pieu sous chargement cyclique de type t-z. Les premières simulations effectuées montrent un bon accord entre le modèle et les résultats expérimentaux à petit nombre de cycles / We study in this present work the behavior of the soil-structure interface under large number of cycles (100 000 cycles). An important program with a probe-pile jacked into the beds of sand was carried out in calibration chamber. We interested particularly on the evolution of local skin friction and tip resistance at different initial state of beds (initial density and confining pressure) and the parameters of the load (cyclic displacement amplitude). We conducted an important part of the experimental work under axial cyclic displacement controlled test which allows studying the large number of cycles. After the degradation phase, already observed by several authors (about 1000 cycles), an important re-increase in the skin friction at large cyclic number was observed at low values of initial tip resistance.This re-increase is attributed to a high dilation of sand around the probe. However, for high values of initial tip resistance there is almost not re-increase in the skin friction. This is due tothe formation of a shear band around the probe made of crushed sand. These reduce theroughness of the probe by cementing/sealing. In addition to the displacement-controlled tests, we conducted the load-controlled tests in order to study the stability of the pile. The results showed a good agreement with the displacement-controlled tests. Finally, empirical model of evolution of skin friction and tip resistance have been proposed in order to reproduce the experimental results. This model was incorporated into a computational model of pile under cyclic axial loading. The first simulations showed a good agreement with the experimental results at low number of cycles

<p>The first class of problem we study deals with geometric matchings. Given a set<br />of points in the plane, we study perfect matchings of those points by straight line<br />segments so that the segments do not cross. Bottleneck matching is such a matching that minimizes the length of the longest segment. We are interested in finding a bottleneck matching of points in convex position. In the monochromatic case, where any two points are allowed to be matched, we give an O(n ²)-time algorithm for finding a bottleneck matching, improving upon previously best known algorithm of O(n ³) time complexity. We also study a bichromatic version of this problem, where each point is colored either red or blue, and only points of different color can be matched. We develop a range of tools, for dealing with bichromatic non-crossing matchings of points in convex<br />position. Combining that set of tools with a geometric analysis enable us to solve the<br />problem of finding a bottleneck matching in O(n ²) time. We also design an O(n)-time<br />algorithm for the case where the given points lie on a circle. Previously best known results were O(n 3 ) for points in convex position, and O(n log n) for points on a circle.<br />The second class of problems we study deals with dilation of geometric networks.<br />Given a polygon representing a network, and a point p in the same plane, we aim to<br />extend the network by inserting a line segment, called a feed-link, which connects<br />p to the boundary of the polygon. Once a feed link is fixed, the geometric dilation<br />of some point q on the boundary is the ratio between the length of the shortest path<br />from p to q through the extended network, and their Euclidean distance. The utility of<br />a feed-link is inversely proportional to the maximal dilation over all boundary points.<br />We give a linear time algorithm for computing the feed-link with the minimum overall<br />dilation, thus improving upon the previously known algorithm of complexity that is<br />roughly O(n log n).</p> / <p>Prva klasa problema koju proučavamo tičee se geometrijskih mečinga. Za dat skup tačaaka u ravni, posmatramo savr&scaron;ene mečinge tih tačaka spajajućii ih&nbsp; dužima koje &nbsp; se ne smeju sećui. Bottleneck mečing je takav mečing koji minimizuje dužinu najduže duži. Na&scaron; cilj je da nađemo bottleneck mečiing tačaka u konveksnom položaju.Za monohromatski slučaj, u kom je dozvoljeno upariti svaki par tačaka, dajemo algoritam vremenske složenosti O(n ²) za nalaženje bottleneck mečinga. Ovo&nbsp; je bolje od prethodno najbolji poznatog algoritam, čiija je složenost O(n ³). Takođe proučavamo bihromatsku verziju ovog problema, u kojoj je svaka tačka&nbsp; obojena ili u crveno ili u plavo, i dozvoljeno je upariti samo tačke različite boje. Razvijamo niz alata za rad sa bihromatskim nepresecajućim mečinzima tačaka u konveksnom položaju. Kombinovanje ovih alata sa geometrijskom analizom omogućava nam da re&scaron;imo problem nalaženja bottleneck mečinga u O(n ² ) vremenu. Takođe, konstrui&scaron;emo algoritam vremenske složenosti O(n) za slučaj kada&nbsp; sve date tačkke leže na krugu. Prethodno najbolji poznati algoritmi su imali složenosti&nbsp; O(n ³ ) za tačkeke u konveksnom položaju i O(n log n) za tačke na krugu.<br />Druga klasa problema koju proučaavamo tiče se dilacije u geometrijskim mrežama. Za datu mrežu predstavljenu poligonom, i tačku p u istoj ravni, želimo pro&scaron;iriti mrežu&nbsp; dodavanjem duži zvane feed-link koja povezuje p sa obodom poligona. Kada je feed- link fiksiran, defini&scaron;emo geometrijsku dilaciju neke tačke q na obodu kao odnos izme&nbsp; đu&nbsp; dužine najkraćeg puta od p do q kroz pro&scaron;irenu mrežu i njihovog Euklidskog rastojanja. Korisnost feed-linka je obrnuto proporcionalna najvećoj dilaciji od svih ta čaka na obodu poligona. Konstrui&scaron;emo algoritam linearne vremenske složenosti koji nalazi feed-link sa najmanom sveukupnom dilacijom. Ovim postižemo bolji rezultat od prethodno najboljeg poznatog algoritma složenosti približno O(n log n).</p>

Den fysiska arbetsmiljön är viktig för hälsan. Den kontorstypen vi arbetar i har en betydande påverkan på individen. Vi vet idag att buller, speciellt över en längre tid bidrar till negativa hälsoeffekter. Trots det utformar vi kontor med öppnare landskap där arbetstagare inte kan kontrollera bakgrundsljudet. Den här studien genomförs i en kontrollerad miljö med syfte att synliggöra hur det kan vara att arbeta i ett öppet kontorslandskap och i ett vanligt kontor. Studien mäter både upplevd och observerad arbetsbelastning, samt hur dessa skiljer sig åt i en tyst miljö och en miljö med bakgrundsljud. I experimentet använde vi oss av eye-tracking utrustning för att mäta pupillutvidgning, vilket kan ha ett samband med ökad mental arbetsbelastning. GSR-utrustning användes för att mäta känslosvall och deltagarnas upplevda arbetsbelastning mättes med hjälp av en NASA-TLX enkät. Resultatet visar att miljön med bakgrundsljud upplevdes störande under hela testet. Skillnader i pupillstorleken visade på en ökad mental arbetsbelastning när det fanns ljud i bakgrunden, men bara på de tester som innehöll en läsuppgift. Om arbetsbelastningen blir för hög, kan det enligt tidigare forskning, leda till en negativ påverkan på en persons hälsa. / The physical work environment is important for your health. The type of office we work in have a significant impact on the individual. We know today that noise, especially over a longer period of time contribute to negative health effects. Despite this we continue designing offices with open landscape where workers cannot control the background noise. This study is conducted in a controlled environment with the intention to get a view how it might be to work in an open landscape office and in a regular office. The study measure both perceived and observed mental load, and how these differ in a quiet environment and an environment with background noise. In the experiment we used eye-tracking equipment to measure pupil dilation, which may be associated with increased mental load. GSR-equipment was used to measure emotional arousal and participants perceived workload was measured using a NASA-TLX questionnaire. The result shows that the environment with background noise was experienced as disturbing throughout the test. Differences in pupil dilation showed an increased mental workload when there was sound in the background, but only on the tests that contained a reading task. If the workload becomes too high, it can, according to previous research, lead to a negative impact on a person’s health.

En la presente investigación, se estudiaron los parámetros representativos que influyen en la resistencia al corte de un suelo granular. El objetivo de este estudio es comprobar que se puede obtener el ángulo de fricción de un suelo granular, a través de una expresión lineal de tres variables, y mediante el uso del método de curvas homotéticas. Son muchas las variables que influyen en la resistencia al corte de un suelo granular. Sin embargo, en esta investigación solo se consideran las variables de dilatancia y el ángulo de fricción, esto debido a la delimitación de variables y parámetros desarrollados en el estudio, lo cual se podría considerar para una futura investigación y para la obtención de una expresión con una mayor cantidad de parámetros de influencia en la resistencia al corte. La resistencia al corte de los suelos granulares depende en gran medida del ángulo de fricción y la dilatancia. De esta manera, se realizó un estudio experimental en muestras de arena con la finalidad de obtener una expresión que permita correlacionar los ángulos de fricción de muestras con granulometría original y muestras elaboradas con el criterio de curvas homotéticas. Luego, se realizaron ensayos de densidad máxima y mínima, y ensayos de corte directo, donde se ensayaron especímenes compactados al 70% de densidad relativa. Finalmente, se obtuvo una expresión basada en el ángulo de fricción y la dilatancia, con un coeficiente de determinación de la ecuación cerca a la unidad, lo cual evidencia un claro ajuste de la expresión. / In the present investigation, representative parameters that influence the shear strength of a granular soil were studied. The objective of this study is to verify that the friction angle of a granular soil can be obtained through a linear expression of three variables, and by using the homothetic curve method. There are many variables that influence the shear strength of a granular soil. However, in this investigation only the variables of dilatancy and the friction angle are considered, this due to the delimitation of variables and parameters developed in the study, which could be considered for future investigation and to obtain an expression with a greater number of parameters of influence in the shear strength. The shear strength of granular soils depends to a great extent on the friction angle and the dilatancy. In this way, an experimental study was realized in sand samples in order to obtain an expression that allows correlating the friction angles of samples with original granulometry and samples made with homothetic curves criterion. Then, maximum and minimum density tests and direct shear tests were realized, where specimens compacted at 70% relative density were tested. Finally, an expression based on the angle of friction and the dilatancy was obtained, with a coefficient of determination of the equation close to unity, which shows a clear fit of the expression. / Tesis

Several hydraulic loadings impose earthen levees to time-dependent variably saturated seepage conditions. The main objective of this study is to improve the analysis of levees under transient seepage with the use of unsaturated soil mechanics. An extensive set of laboratory testing, field monitoring and numerical modeling are performed to analyze a silty sand setback levee located near Seattle, WA. In-situ data obtained from field monitoring are used to monitor suction and effective stress within the levee’s embankment and foundation over the past two years. Soil samples taken from the site are used to perform index, water retention, and unsaturated multi-stage triaxial tests in the laboratory. A finite element model of transient seepage under saturated-unsaturated conditions is then developed and calibrated to reasonably match the field data. The results highlight the need to consider unsaturated soil mechanics along with climatic variables and soil-atmosphere interaction when analyzing levees under transient seepage conditions.

La charge de travail cognitive d'un pilote d'aviation, qui englobe sa capacité mentale à effectuer les manœuvres d'un avion, varie selon l’étape de pilotage et le nombre de tâches convergeant simultanément sur le pilote. Cette charge de travail peut entraîner des erreurs de pilotage aux conséquences graves. La plupart des erreurs se produisent pendant la procédure de décollage ou d'atterrissage. Cette étude vise à mesurer et prédire la charge de travail cognitive d'un pilote lors d'une procédure de décollage afin de mieux comprendre et potentiellement prévenir ces erreurs humaines. Pour y parvenir, nous avons créé une solution logicielle pour mesurer et surveiller en temps réel la fréquence cardiaque, la dilatation pupillaire et la charge de travail cognitive d'un pilote. Le logiciel est également capable de déclencher des événements de défaillance pour déclencher une modification de la charge de travail cognitive à la demande. À l'aide d'un casque électroencéphalogramme (EEG) permettant de mesurer l’activité électrique du cerveau, d'un moniteur de fréquence cardiaque, d'un eye tracker et d'un simulateur, nous avons créé une configuration d'environnement où les pilotes devaient faire décoller un avion A320 avec et sans pannes sans le savoir au préalable. Cette étude a rassemblé 136 décollages sur 13 pilotes pour plus de 9 heures de données de séries chronologiques, soit 2 millions de lignes combinées. De plus, nous avons étudié la relation entre la fréquence cardiaque, la dilatation de la pupille et la charge de travail cognitive lors d'une tâche critique. Cette étude a révélé, à l'aide d'une analyse statistique, qu'un moment critique, comme une panne de moteur, augmente la fréquence cardiaque, la dilatation de la pupille et la charge de travail cognitive d'un pilote. Ensuite, cette recherche a utilisé différents modèles d'apprentissage automatique et d'apprentissage en profondeur pour prédire la charge de travail cognitive d'un pilote pendant le décollage. Nous avons constaté qu'en utilisant un modèle d'apprentissage en profondeur long short-term memory empilé, nous étions en mesure de prédire la charge de travail cognitive 5 secondes dans le futur. Le modèle long short-term memory empilé a donné une erreur quadratique moyenne (MSE) de 44,09, une erreur racine quadratique moyenne (RMSE) de 6,64 et une erreur absolue moyenne de 5,28, prouvant qu'il est possible de prédire la charge de travail cognitive. / The cognitive workload for an aviation pilot, which englobes a pilot's mental capacity to perform aircraft's maneuvers, varies according to the piloting stage and the number of tasks converging simultaneously on the pilot. This workload can lead to piloting errors with severe consequences, where most errors occur during the takeoff or landing procedure. This study aims to predict the cognitive workload of a pilot during a takeoff procedure in order to better understand and potentially prevent these human errors. To achieve this, we created a software solution to measure and monitor in real-time the heart rate, pupil dilation, and cognitive workload of a pilot. The software is also capable of triggering failure events to trigger a change in cognitive workload on demand. Using an electroencephalogram (EEG) headset which measures the electrical brain activity, a heart rate monitor, an eye tracker, and a simulator, we created an environment setup where pilots had to take off an A320 airplane with and without failures without priorly knowing it. This study gathered 136 takeoffs across 13 pilots for more than 9 hours of time-series data, or 2 million rows combined. Moreover, we investigated the relation between heart rate, pupil dilation, and cognitive workload during a critical task. This study found, using statistical F-test analysis, that a critical moment, such as an engine failure, augments the heart rate, pupil dilation, and cognitive workload of a pilot. Next, this research utilized different machine learning and deep learning models to predict the cognitive workload of a pilot during takeoff. We found that, when using a stacked long short-term memory deep learning model, we were able to predict future cognitive workload 5 seconds into the future. The stacked long short-term memory model resulted in a mean square error of 44.09, a root mean square error of 6.64, and an mean absolute error of 5.28, demonstrating that it is possible to predict future cognitive workload.

<p>The fluid dynamics of blood in the systemic circulation modulates production of nitric oxide (NO), a potent vasodilator. Non-invasive techniques such as the flow-mediated dilation (FMD) test and physiologic phenomena associated with autonomic stress induce hyperemia and subsequently higher levels of wall shear stress (WSS), stimulating endothelial nitric oxide synthase (eNOS) expression. In the current clinical practice, WSS–a key regulator of endothelial function–is commonly estimated assuming a parabolic velocity distribution, despite the evidence that the temporal changes of pulsatile blood flow over the cardiac cycle modulate vasodilation in mammals. This work investigates the effect of cardiovascular stress on local WSS distributions and the potential for near-wall accumulation of nitrite, the vasoactive storage form of NO in the bloodstream. The specific aims of the project are therefore as follows: 1) develop a reduced-order model of the major systemic vasculature at rest, during a flight-or-flight response, and under moderate levels of aerobic exercise; 2) derive a velocity-driven Womersley solution for pulsatile flow to support accurate estimation of pulsatile WSS in the clinical setting; and 3) quantify cumulative transport of nitrite in a multiscale model of bifurcating vasculature utilizing computational fluid dynamics (CFD). Development of these open-source, translatable methods enable accurate quantification of hemodynamics and species transport during cardiovascular stress. Results detailed herein extend our knowledge about regulation of regional blood flow during autonomic stress, suggest a convergent evolutionary theory for having a complete circle of Willis, and potentially clarify reproducibility concerns associated with the FMD test. </p>

Pendant les opérations de vol, les pilotes sont exposés à une variété de conditions émotionnelles, mentales et physiques qui peuvent affecter leurs performances et leur attention. Par conséquent, il est crucial de surveiller leur charge de travail et leurs niveaux d'attention pour maintenir la sécurité et l'efficacité de l'aviation, notamment dans les situations d'urgence. La charge de travail fait référence aux exigences cognitives et physiques imposées aux pilotes lors d'un vol. Des niveaux élevés de charge de travail peuvent entraîner une fatigue mentale, une attention réduite et une surcharge cognitive, ce qui peut entraver leur capacité à effectuer leurs tâches de manière efficace et efficiente. L'attention est un processus cognitif complexe qui limite la capacité de se concentrer et de comprendre tout en même temps. Dans les tâches de traitement de l'information visuelle, la vision humaine est la principale source du mécanisme d'attention visuelle. Le mode de distribution de l'attention d'un pilote a un impact significatif sur la quantité d'informations qu'il acquiert, car la vision est le canal le plus critique pour l'acquisition d'informations. Une mauvaise allocation des ressources attentionnelles peut amener les pilotes à négliger ou à oublier des paramètres spécifiques, ce qui entraîne des risques graves pour la sécurité des aéronefs. Ainsi, cette étude vise à étudier les niveaux d'attention des pilotes lors d'une procédure de décollage simulée, en mettant l'accent particulièrement sur les périodes critiques telles que les pannes de moteur. Pour ce faire, l'étude examine s'il existe une corrélation entre la dilatation de la pupille, mesurée à l'aide de la technologie de suivi oculaire, et les niveaux d'engagement, mesurés à l'aide de l'EEG. Les résultats indiquent que les changements de taille de la pupille sont effectivement corrélés aux changements d'activité de l'EEG, suggérant que la dilatation de la pupille peut être utilisée comme un indicateur fiable de l'engagement et de l'attention. Sur la base de ces résultats, la dilatation de la pupille et l'EEG peuvent être utilisés en combinaison pour examiner de manière globale le comportement des pilotes, car les deux mesures sont des indicateurs valides de l'engagement et de la charge cognitive. De plus, l'utilisation de ces mesures peut aider à identifier les périodes critiques où les niveaux d'attention des pilotes nécessitent une surveillance étroite pour garantir la sécurité et l'efficacité de l'aviation. Cette étude met en évidence l'importance de surveiller la charge de travail et les niveaux d'attention des pilotes et recommande d'utiliser les mesures de dilatation de la pupille et d'EEG pour évaluer la charge cognitive et l'engagement d'un pilote pendant les opérations de vol, améliorant ainsi la sécurité et l'efficacité de l'aviation. / During flight operations, pilots are exposed to a variety of emotional, mental, and physical conditions that can affect their performance and attention. Therefore, it is crucial to monitor their workload and attention levels to maintain aviation safety and efficiency, particularly in emergency situations. Workload refers to the cognitive and physical demands placed on pilots during a flight. High levels of workload can lead to mental fatigue, reduced attention, and cognitive overload, which can hinder their ability to perform their tasks effectively and efficiently. Attention is a complex cognitive process that limits the ability to focus and comprehend everything simultaneously. In visual information processing tasks, human vision is the primary source of the visual attention mechanism. A pilot's attention distribution mode significantly impacts the amount of information they acquire, as vision is the most critical channel for information acquisition. Improper allocation of attention resources can cause pilots to overlook or forget specific parameters, resulting in severe risks to aircraft safety. Thus, this study aims to investigate pilots' attention levels during a simulated takeoff procedure, with a specific focus on critical periods such as engine failures. To achieve this, the study examines whether there is a correlation between pupil dilation, measured using eye-tracking technology, and engagement levels, measured using EEG. The results indicate that changes in pupil size are indeed correlated with changes in EEG activity, suggesting that pupil dilation can be used as a reliable indicator of engagement and attention. Based on these findings, pupil dilation and EEG can be used in combination to comprehensively examine pilot behavior since both measures are valid indicators of engagement and cognitive workload. Furthermore, using these measures can help identify critical periods where pilots' attention levels require close monitoring to ensure aviation safety and efficiency. This study emphasizes the significance of monitoring pilots' workload and attention levels and recommends using pupil dilation and EEG measures to assess a pilot's cognitive workload and engagement during flight operations, ultimately enhancing aviation safety and efficiency.