identifier: Abbasi, Arash  (2022). Low-power wideband receiver front-end design for short-range IoT applications.  Thèse de doctorat électronique, Montréal, École de technologie supérieure.

subject:
IoT
current-reuse receiver
low noise amplifier
wideband
low-power

abstract:
The fast growth of the internet-of-things (IoT) promises the establishment of a smart environment including home automation, health monitoring, location tracking etc. Billions of IoT devices are needed to achieve this goal and connect the objects around us. This introduces a need to develop low-power IoT devices. Accordingly, reducing by a fraction of the power consumption in each IoT device can lead to an important overall energy use reduction globally. undoubtedly, the RF transceiver plays a significant role to define the overall power consumption of the IoT module.

The aim of this work is to develop a low-power and wideband current-reuse receiver front-end for IoT applications. The wideband feature covers several frequency bands to reduce the number of receivers required. To do this, first, a literature review is presented. It focuses on the low-power receiver design techniques and discusses the circuits in detail.

Following the literature review, A detailed design tutorial including the design procedures and characterization results is presented to provide a systematic design approach of the current-reuse receiver front-end to breakdown the circuit to sub-blocks and perform the design as a conventional receiver architecture.

A low-power RF-to-BB current-reuse receiver front-end using an active-inductor and 1/ f noise-cancellation techniques for L-band applications is presented. The active-inductor improves the receiver noise-figure at higher frequencies and the noise-cancellation technique suppresses the low frequency noise. Both active-inductor and 1/ f noise-cancellation techniques help enhance the receiver noise figure. The effect of the metal fill on the performance is studied in measurements that shows the notable improvement in the noise figure performance.

A comparison of an off-chip differential and an LC Balun employing the same current-reuse receiver front-end with and without an on-chip inductor is presented to evaluate the performance using different matching networks and frequencies. This demonstrates that the receiver can be tuned to any frequency band by adjusting the matching network.

Overall, this thesis describes the study, design and characterization of low-power and wideband current-reuse receiver front-ends that can be tuned for any frequency band to be used for different IoT applications. The active-inductor and 1/ f noise-cancellation techniques introduced in this work improve the performance of the receiver and allow it to maintain its performance at higher frequencies even in a relatively large 130 nm CMOS process.


identifier: Shahin Moghadam, Asad  (2022). A message-driven architecture to integrate isolated building data into digital twins.  Mémoire de maîtrise électronique, Montréal, École de technologie supérieure.

type:
Mémoire ou thèse
Non évalué par les pairs

subject: jumeau numérique

subject: construction

subject: intégration des données

subject: gestion des installations

subject: système de construction

subject: capteurs isolés

subject: DMZ

subject: architecture axée sur les messages

subject: informatique en nuage (cloud computing)

abstract:
This thesis aims at developing and implementing a framework for the Digital Twin (DT) of buildings that their systems are inside a network-wised isolated environment, hence face data integration challenges. There are several studies focusing on conceptual models and implementation of DT in Architecture, Engineering, Construction, Operation and Facility Management (AECO-FM). DTs can be applied to facility management, preventive maintenance, monitoring and anomaly detection, and enhance the efficiency of constructions projects and workforce safety. However, due to certain features of this industry, this sector has been slow in adoption of DTs. Moreover, despite increasing number of DT implementations, less attention has been given to the challenges of implementing them. Data integration issues including data access, collection, storage and exchange are among the main challenges identified by scholars. Specifically, the majority of DT studies have assumed that data are readily accessible for implementing DTs, while it is rarely the case in practice.

This research focuses on the data integration problem in implementing a DT in buildings where accessing sensor data is restricted for various reasons such as data accessibility and privacy issues, or due to deployed legacy BMS/BAS systems. A methodological framework for implementing a DT in such scenarios is presented in which file-based offline sensory data is transformed to message-based online data. In addition, a distributed message-driven architecture is designed to implement this methodological framework. A case study of a community center is implemented to assess the applicability of the proposed methodological framework.

This thesis contributes to the field, by relaxing the widespread assumption of easy data accessibility for DT implementation in the literature. The proposed methodological framework and its cloud-native software architecture can be applied to similar scenarios in which sensory data is not readily accessible. The proposed framework is reusable, scalable and flexible in the data types that it can handle. Moreover, Data is critical to collaborations within AECO-FM projects. Therefore, this study is beneficial to practitioners as well allowing them to use the potentials of untapped data which is being constantly collected in data silos of legacy systems of various stakeholders but kept isolated.


identifier: Mechichi, Sarah  (2022). Commande d’un manipulateur aérien avec l’approche de décomposition virtuelle.  Mémoire de maîtrise électronique, Montréal, École de technologie supérieure.

subject:
manipulation aérienne
décomposition virtuelle
loi d’adaptation
commande robuste

abstract: Le but de ce mémoire est de commander un manipulateur aérien par l’approche de contrôle par décomposition virtuelle (CDV). Le système étudié se composera d’un drone de châssis S500 et d’un manipulateur sériel à 2 degrés de liberté. Dans un premier temps, les modèles cinématique et dynamique du système seront élaborés. Dans un second temps, une commande d’altitude et d’orientation sera développée. Trois cas de commande seront présentés. Le premier consiste à appliquer les lois de commande classique de la méthode CDV. Les deux autres cas consistent à robustifier le cas précédent en employant les fonctions signe et tangente hyperbolique. Pour obtenir les différents paramètres physiques du système, un assemblage du système aérien sera réalisé sous SolidWorks. Cet assemblage sera constitué d’un design du drone S500 préexistant et d’un bras sériel conçu grâce au même logiciel pour répondre aux besoins. Pour valider les commandes développées, deux types de simulations seront effectuées. La première sera réalisée sous l’environnement de simulation MATLAB/ Simulink et sera effectuée pour deux scénarios de mouvement. Le Scénario I sera appliqué sur les trois cas de commande pour déterminer le cas permettant d’avoir les meilleures performances du système. Quant au Scénario II, il permettra de simuler les performances du système, en employant le cas de commande précédemment sélectionné, pour des trajectoires polynomiales cubiques. Le deuxième type de simulation sera sous Simscape Multibody consistera à appliquer le Scénario II sur l’assemblage réalisé et importé sous l’environnement mécanique de Matlab dans le but d’observer le mouvement du système de manipulation ainsi que les améliorations qui en découlent.


identifier: Bérubé, Étienne  (2022). Conception d’un réacteur tubulaire sous pression d’ozonation pour l’enlèvement des organismes fongiques et des moisissures aquatiques des eaux piscicoles.  Mémoire de maîtrise électronique, Montréal, École de technologie supérieure.

subject:
ozone
système d’aquaculture en recirculation
désinfection
qualité de l’eau
micro-organismes fongiques
moisissures aquatiques

abstract:
Les systèmes d’aquaculture en recirculation permettent une production de biomasse supérieure tout en réduisant l’espace nécessaire à l’élevage, mais cette augmentation de production est caractérisée par une augmentation de la densité des poissons dans les bassins d’élevage et un risque supérieur de transmission de maladies. Les épidémies en milieu d’élevage de salmonidés représentent un problème pour les productions piscicoles. L’interdiction d’utilisation du produit antifongique utilisé par la majorité des piscicultures, le vert de malachite, a amplifié ce problème. L’objectif de ce mémoire est de développer une technologie, soit un nouveau type de réacteur d’ozonation pour les piscicultures, dans le but de résoudre cette problématique d’épidémies en milieu d’élevage piscicole.

Un réacteur tubulaire horizontal d’hydro-injection d’ozone a été élaboré et installé sur les bassins de classement de la Pisciculture Gilbert. Des essais d’enlèvement de micro-organismes pathogènes et de suivi de la cinétique de consommation de l’ozone dans le réacteur ont été effectués. La détermination des paramètres de qualité physico-chimique des eaux d’élevage a montré que la qualité du milieu d’élevage se situe sous les limites de tolérance des poissons. Les échantillons étaient collectés sur le terrain et analysés en laboratoire. L’ajout de l’ozone a permis la réduction de 1.2 ± 0.3 log des organismes fongiques et semi-fongiques à l’aide d’un traitement correspondant à une valeur de Ct de 3.0 mg⋅min/L. Les essais d’ozonation ont montré que la consommation de l’ozone obéit à la loi du premier ordre et détient deux constantes de vitesse distinctes : 0.004 ± 0.001 s-1 et 0.013 ± 0.004 s-1. Cette différence d’un ordre de grandeur s’explique par des augmentations du taux de recirculation du système d’élevage piscicole. Par exemple, un problème de pompe stoppant l’apport en eau neuve et augmentant donc le taux de recirculation a causé une augmentation d’un ordre de grandeur de la vitesse de consommation de l’ozone. De plus, la vitesse de consommation de l’ozone varie selon la charge en matière organique et en micro-organismes. Du maillage plastique a été installé à l’intérieur des tubes pour maximiser la turbulence du réacteur d’ozonation (10200 Re et facteur de friction de 0.06) en plus de favoriser le mélange du gaz avec l’eau par l’installation de 40 mélangeurs statiques. Le réacteur présente une efficacité hydraulique λ de 0.96, indiquant un bon écoulement sans la présence de zones mortes. Les résultats d’enlèvement des micro-organismes et les conditions d’opération du réacteur supporte l’utilisation de celui-ci en milieu piscicole. Ainsi, l’ozonation constitue une option alternative aux traitements antifongiques actuels.


identifier: Bui, Thi Thuyet  (2022). Autoregressive model updating for modal analysis of non-stationary vibration systems.  Thèse de doctorat électronique, Montréal, École de technologie supérieure.

subject:
modèle autorégressif
moindres carrés récursifs
sélection de l'ordre du modèle
identification des paramètres modaux
système variable
fenêtre glissante

abstract:
Operational modal analysis (OMA) has recently become one of the most effective techniques to extract modal parameters (natural frequencies, damping ratios, and mode shapes) for practical vibrations under working conditions. Many good results have been observed in numerous domains, such as robotics, fluid-structure interaction, and bridges. Due to these applications being considered under working conditions, their modal parameters change over time. Hence, identifying the operational modal parameters in structures is a computationally complex and time-consuming procedure. In addition, collected non-stationary signals are usually mixed with heavy noise caused by operating conditions or changing environments. Consequently, problem resolution using least-squares is rank deficient. To mitigate these disadvantages in OMA, it is essential to develop updating algorithms.

The main objective of this study is to develop novel algorithms to reduce the computational complexity, time burden, and matrix singularity for the modal identification of OMA. The proposed methods can be applied to slow-varying non-stationary vibration structures and are validated by experiments on the fluid-structure interaction. To achieve this, the research is conducted in two steps.

The objective of the first step is to present a novel method for updating model parameters of autoregressive models and monitoring the change of modal parameters for slow-varying nonstationary vibration systems. This method avoids computational complexity and timeconsuming modal analysis for slow-varying non-stationary vibration systems. The sliding window technique is used to extract modal parameters for systems. For this objective, the Schur complement is applied to the sliding window to update model parameters in time and order. Numerical simulation and experiments on an emerging plate are effective ways to validate that the proposed approach enhances performance in terms of computational complexity and execution time. In addition, the proposed method is used to monitor and track the change of modal parameters for slow-varying non-stationary systems. Restrictions of the proposed approach are also discussed. The results of the first step have been accepted for publication in the Journal of Mechanical Systems and Signal Processing (MSSP).

Based on the promising results regarding reduced computational complexity and execution time for modal analysis identification, the second step is also to develop an updating algorithm, which can be applied to structures under working conditions with only the output vibratory responses. In addition, the proposed method copes with the matrix singularity caused by operating conditions for operational modal analysis. The basic idea of this method consists of using a short-time sliding window (STSW) to identify modal parameters for slow-varying nonstationary vibration structures. This method uses the recursive multivariable least-squares method with singular value decomposition (SVD) to find the solutions in a data segment from each time window. The updating model identification is conducted by updating the SVD of the data matrix through the order and time from the previous computational window to monitor the modal parameters of the slow-varying non-stationary systems. Prospective applications are found in the modal analysis of the submerged hydraulic turbines excited by turbulent flows to extract and monitor the change of modal parameters. The results of this step have been submitted to the Journal of Mechanical Systems and Signal Processing (MSSP) for publication.


identifier: Molinier, Nathan  (2022). Imagerie ultrasonore par réseaux antagonistes génératifs conditionnels (cGAN).  Mémoire de maîtrise électronique, Montréal, École de technologie supérieure.

subject:
DAS
TFM
FMC
Contrôle non destructif
ultrasons
onde plane (PW)
cGAN

abstract: La mise en forme des faisceaux avec la méthode de somme et de retard (de l’anglais DelayAnd-Sum : DAS) en combinaison avec une acquisition de type capture matricielle complète (de l’anglais Full-Matrix-Capture : FMC) est une méthode encore aujourd’hui extrêmement utilisée dans le contrôle non destructif pour un grand nombre d’applications d’imagerie ultrasonore. Cependant, dans certains cas, comme les inspections à haute cadence, il est impossible d’envisager une telle méthode sans ralentir le processus. C’est pourquoi dans cette étude, nous avons cherché à contourner cette méthode standard en utilisant un réseau adversaire génératif conditionnel (de l’anglais conditional Generative Adversarial Network : cGAN) en combinaison avec des acquisitions type onde plane à zéro degré. Dans ce mémoire, trois différents modèles de cGAN ont été testés avec différentes fonctions de coût dans trois configurations différentes et les résultats ont été comparés à ceux obtenus grâce à la méthode conventionnelle. Les différents modèles ont été capables de reconstruire avec des résolutions équivalentes les images tout en améliorant dans plus de la moitié des cas le contraste, et en réduisant le niveau de bruit et les artéfacts dans les images. De plus, la méthode proposée a permis de diviser le temps de calcul par 120 et le temps d’acquisition par 64 tout en divisant l’espace de stockage nécessaire aux données d’entrée par 75.


identifier: Montazer Zohour, Hamed  (2022). An analytical approach to safe collaborative assembly station with cobots.  Mémoire de maîtrise électronique, Montréal, École de technologie supérieure.

subject:
robotique
cinématique
tâches collaboratives
minimisation de l’occlusion

abstract:
Robotics is an interdisciplinary science encompassing vast fields of research: vision, motion planning, control, locomotion, design, and so on. The objective of the creation of robots in the early sixties was to relieve man of certain hard jobs such as: handling a heavy object, and repetitive tasks often tiring or even sometimes infeasible manually. Following this situation, several kinds of manipulators were created . Historically, the manipulator arms were the first manufactured and still are widely used in industry. These robotic systems have the ability to act on the environment through the realization of manipulation tasks such as the grasping of objects, the assembly of pieces, etc. They are nevertheless very limited in their operational workspace and in the type of work they can achieve.

New applications where robots are employed near humans are growing rapidly. Unlike industrial robots, which are used in cages to guarantee high precision and safety, collaborative robots, also called Cobots, are designed with a high degree of compliance to ensure safety in presence of humans.

Several industrial pick-and-place applications, such as collaborative assembly lines, rely on visual tracking of the parts. Recurrent occlusions caused by the manipulator motion decrease line productivity and can provoke failures. This work provides a complete solution for maintaining an occlusion-free line of sight between a variable-pose camera and the object to be picked by a 6R manipulator that is not wrist-partitioned. We consider potential occlusions by the manipulator as well as the operator working at the assembly station. An actuated camera detects the object goal (part to pick) and keeps track of the operator. The approach consists in using the complete set of solutions obtained from the derivation of the univariate polynomial equation solution to the inverse kinematics (IK). Compared to numerical iterative solving methods, our strategy grants us with a set of joint positions (posture) for each root of the equation from which we extract the best (minimizing the risks of occlusion). Our analytical-based method, integrating collision and occlusion avoidance optimizations, can contribute to greatly enhancing efficiency and safety of collaborative assembly workstations.


identifier: Poulin, Samuel  (2022). Analyse quantitative de l’électroencéphalogramme en sommeil paradoxal.  Mémoire de maîtrise électronique, Montréal, École de technologie supérieure.

subject: détection des artéfacts oculaires (AO)

subject: électroencéphalogramme (EEG)

subject: sommeil paradoxal (REM)

subject: analyse par composante indépendante (ICA)

subject: micro-états

subject: Snooz

abstract: L’analyse de l’électroencéphalogramme (EEG) durant le sommeil paradoxal (REM) est une problématique dans tous les domaines nécessitant cette analyse que ce soit pour l’étude du trouble comportemental en sommeil paradoxal (TCSP) ou l’étude des micro-états par exemple. Le problème majeur rencontré en REM demeure l’omniprésence des mouvements oculaires rapides (MOR) dans l’EEG et ceux-ci masquent l’activité cérébrale sous-jacente. Ce mémoire offre une méthode afin de corriger automatiquement les artéfacts oculaires (AO) présents sur l’EEG à l’aide d’une analyse par composantes indépendantes (ICA). De plus, un détecteur de mouvement oculaire rapide semi-automatique sera implémenté en sommeil paradoxal afin d’augmenter la précision du correcteur ainsi qu’offrir un outil essentiel pour l’analyse du REM pour les patients RBD (REM Sleep Behaviour Disorder). Finalement, l’analyse des techniques permettant d’identifier les micro-états durant le sommeil paradoxal complétera cette analyse quantitative. Ces topographies caractéristiques visibles sur le scalpe sont une représentation de l’activité cérébrale sous-jacente, donc il est primordial de nettoyer la trace d’activité oculaire sur l’EEG de REM afin de ne pas biaiser ces micro-états. Ce mémoire offre donc un algorithme permettant de corriger tout en préservant l’activité thêta et même l’augmenter un peu en REM ainsi que réduire l’activité delta associée aux mouvements oculaires. Un détecteur semiautomatique permet de faire une première passe très rapidement et ainsi grandement accélérer la détection des experts pour ensuite présenter les micro-états en sommeil paradoxal. Ces outils permettront d’analyser l’intégralité du sommeil paradoxal, mais surtout découvrir le procédé réalisé par le cerveau lors de ces micro-états. Tous ces outils seront disponibles via l’application Snooz développée au Centre d'études avancées en médecine du sommeil (CÉAMS) permettant aux chercheurs et aux cliniciens d’effectuer des analyses numériques sur le sommeil grâce aux outils qui seront accessibles. Cette plateforme permettra aussi aux intéressés d’implémenter leurs propres outils sur le sommeil.


identifier: Xu, Huiyang  (2022). A finite element model of a human head and a corresponding acoustic test fixture to assess the objective occlusion effect induced by earplugs under bone-conducted stimulation.  Thèse de doctorat électronique, Montréal, École de technologie supérieure.

subject:
effet d’occlusion
modélisation par éléments finis
tête artificielle
bouchon d’oreille

abstract:
The occlusion effect refers to the increased perception of bone-conducted sounds (e.g., physiological noises like one’s own voice, breathing, chewing, heartbeat) when one wears hearing protection devices, and it constitutes a major acoustic discomfort factor. This phenomenon occurs mainly at low frequencies (below 1.0 kHz) and is particularly pronounced for earplug-type hearing protection devices.

This thesis is interested in assessing the occlusion effect of earplugs using virtual and physical testers both based on the same real head geometry of a living participant. The virtual tester consists of a finite-element head model whereas the physical one corresponds to an augmented acoustic test fixture (i.e., a realistic artificial head). The finite-element head model is evaluated by comparing numerical results with experimental data (i) available in the literature obtained on groups of participants, (ii) obtained on the augmented acoustic test fixture, and (iii) measured on the participant whose head is used for constructing the geometrical head model. The augmented acoustic test fixture is evaluated itself by comparing the occlusion effect of a foam earplug measured on it and on the participant.

In fact, several numerical models for studying the occlusion effect are available in the literature. However, it is found that boundary and loading conditions greatly affect the simulation results of these models due to the consideration of truncated outer ears. On the contrary, the finite-element head model developed in this thesis is found to be only sensitive to the boundary conditions on the artificial boundaries created by the truncation (at the head base in this case) at very low frequencies. It thus avoids choosing boundary conditions so that the corresponding simulation results match the experimental data at the best. Moreover, the finite-element model includes an external air domain surrounding the entire head. A perfectly absorbing condition (i.e., perfectly matched layer) is applied to the boundaries of the air domain, which simulates a free sound field. This allows for taking into account the radiation from the soft tissues of the head into the open earcanal. The present numerical model thus simulates the occlusion effect that better matches experimental data at low frequencies. Thirdly, the finite-element head model allows for investigating the effect on the occlusion effect of the stimulation position. The sensitivity of the occlusion effect to the stimulation position for a given part of the head (e.g., the ipsilateral mastoid) suggests that this factor contributes to the variability of the experimental data obtained on groups of participants in the literature. In this study, the present model is also used to investigate the variability of the occlusion effect induced by the material properties of the earcanal surrounding tissues (i.e., soft tissues, cartilage, and bone). The stiffness parameters (i.e., Young’s modulus and Poisson’s ratio) of the soft tissues and the cartilage are found to affect the occlusion effect the most compared with the other parameters. Besides, the sound fields in the open and occluded earcanals under bone-conducted stimulation are explored using the finite-element head model. Results suggest that the occlusion effect measured at the eardrum position is similar to that assessed at the position of the earplug medial surface. The latter position is safer and more comfortable for the human subjects involved. Finally, the experimental evaluation of the augmented acoustic test fixture shows that in contrast to the measurement on the participant, the occlusion effect of earplugs does not decrease with frequency, which is mainly due to the mechanical properties of the materials used for its fabrication.

In the long term, after robust validation and calibration, the augmented acoustic test fixture developed during this project could serve as a powerful tool for evaluating the acoustic performance of earplugs (e.g., occlusion effect and sound attenuation).


identifier: Brial, Victor  (2022). Étude de la valorisation des brasques traitées comme liants cimentaires.  Thèse de doctorat électronique, Montréal, École de technologie supérieure.

subject:
LCLL Ash
brasques traitées
production d’aluminium primaire
ajouts cimentaires
réactivité
ciment

abstract:
Les brasques usées issues de la production d’aluminium primaire (appelée spent pot lining (SPL) en anglais) sont une matière dangereuse générée par les cellules d'électrolyse en fin de vie. Le SPL est séparé en deux parties, la première riche en matériaux carbonés et la seconde riche en réfractaires vitrifiés. Le traitement de la partie réfractaire du SPL par le procédé industriel LCL&L (Low Caustic Leaching and Liming) génère un résidu inerte non dangereux, appelé LCLL Ash.

Avec une production de 4 milliards de tonnes en 2018, le béton est l'un des matériaux les plus consommés au monde. Néanmoins, l'industrie du béton consomme aussi beaucoup de ressources naturelles et d'énergie, causant d'importantes émissions de gaz à effet de serre (GES). L’une des meilleures solutions pour réduire l’impact environnemental des bétons est d’utiliser des ajouts cimentaires (SCM). L’objectif de la présente thèse est d’étudier la possibilité de valorisation du LCLL Ash comme matériaux cimentaire.

Ce projet de doctorat se divise en trois objectifs spécifiques. Le premier objectif s’intéresse à la caractérisation du LCLL Ash, et à la compréhension de l’impact de l’ajout de LCLL Ash sur les propriétés des matériaux cimentaires. Le second objectif spécifique de la thèse vise à étudier la réactivité du LCLL Ash selon les méthodes standardisées et par méthodes avancées. Le troisième objectif spécifique se concentre sur l’amélioration de la réactivité du LCLL Ash comme liant cimentaire. Pour ce faire, cet objectif spécifique est divisé en quatre sous-objectifs visant à identifier la température de calcination idéale, et évaluer l’impact de l’addition de fluorite sur la calcination du LCLL Ash. Enfin les deux derniers sous-objectifs, se sont concentrés sur des essais exploratoires pour améliorer le LCLL Ash avec des mélanges ternaires et par la synthèse de ciments alternatifs.

L’étude des diffèrent objectifs spécifiques a montré que le LCLL Ash est une poudre composée de phases cristallines stables telles que l'albite, la néphéline, de corindon, et des résidus de graphite. Le LCLL Ash a montré un comportement similaire à un filler, comme la poudre de quartz. La calcination du LCLL Ash à 1050°C a montré une nette augmentation de la réactivité avec un comportement pouzzolanique visible par un indice de réactivité similaire à ceux des cendres volantes. L’influence de la température de calcination sur la réactivité du LCLL Ash a ensuite été étudiée à l’aide des essais Frattini et R3 . Avec des températures de calcination allant de 600°C à 1200°C, deux comportements ont pu être identifiés. À 800°C une augmentation de la réactivité similaire à celle d’un ajout pouzzolanique moyennement réactif a été observée. Cette augmentation s’accompagne d’une diminution des alcalis dans la solution poreuse. Pour des températures de 1000°C et plus, une réactivité offrant des performances similaires à une cendre volante de classe N a été observée. Afin de favoriser la formation de phases amorphes lors de la calcination, l’ajout de fluorite, un autre sous-produit du procédé LCL&L, a été étudié à 800°C et 1000°C selon les méthodes précédentes. À 1000°C, et avec un remplacement de 10 % en masse de fluorite, une augmentation significative de la réactivité a été observée, avec un comportement entre un laitier de haut fourneau et une cendre volante de classe N. Au-delà d’un remplacement de 10 %, la fluorite en excès ne permet plus d’augmenter la réactivité du LCLL Ash calciné. Enfin, des essais exploratoires ont été menés afin de déterminer si l’inclusion du LCLL Ash sans calcination, dans des mélanges ternaires ou pour la synthèse de ciment alternatif, pourrait s’avérer avantageuse. Les mélanges ternaires à base de LCLL Ash non calciné n’ont pas montré d’amélioration. La synthèse de ciment à base de LCLL Ash a permis d’obtenir des ciments belitique, riche en mayenite.


identifier: Emamgholi, Bita  (2022). Investigation of the rejuvenator content effect on the mechanical characteristics of cold recycled asphalt mixes.  Mémoire de maîtrise électronique, Montréal, École de technologie supérieure.

subject:
rajeunisseur
GBR
regroupement
chimie du bitume
IDT
FTIR
analyse rhéologique
mélange à froid

abstract:
Asphalt pavements usually lose their essential bituminous components by the time (as they age) which leads to cracking, brittleness and in general low mechanical properties of the pavement. Therefore, pavements need a partial or full treating (recycling) to prevent its deterioration. Nowadays, aside from the conventional hot recycling methods, cold recycling pavement technologies due to the energy source's limitation and also environmental concerns (eliminating of fume and particle emission to the atmosphere) are highly in demand. Maintenance activities of old pavements (that need rehabilitation) using secondary and waste materials (Reclaimed Asphalt Pavement (RAP) produced by crunching old bituminous pavement) is of important manifestations of the construction potential share in the sustainability goals. Cold Recycled Mixes (CRM) can be made of 100% of recycled materials. However, one of the major challenges in this process is that, the bitumen included in the recycled materials is not usable in the new mix. Therefore, adding a high amount of new bitumen to the base pavement increases the process cost.

The use of a rejuvenator could potentially mobilize the aged binder included in the recycled material, and it would change the behaviour of the mix and asphalt binder leading to higher possible amount of RAP usage in the mixture, enhanced cracking and rutting resistance. The positive effect of rejuvenators in the hot asphalt recycling has been approved in the literature. The main objective of the present research was to evaluate the feasibility of using a rejuvenator with cold recycled materials. The specific objectives were to assess the physical and chemical interaction between the RAP and its bitumen content with the additive rejuvenator. This was aimed to quantify the impact of the rejuvenator addition in cold recycled mixes (CRM) rehabilitation (such as new cluster creation) and RAP rheological properties (tensile strength), and its corresponding rehabilitated bitumen properties. The secondary objective was then to optimize the amount of added bitumen to those mixes using effective employment of rejuvenators in different cold mix preparation scenarios. To do so the effect of rejuvenator content in different aspects of asphalt rehabilitation including clustering effect, and rheological characterization of the cold mixes were examined in different conditions of specimen preparation. Several specimen characteristics and specimen preparation parameters such as RAP size, RAP content in the mixture, specimen preparation temperature, curing time, compaction were analyzed in parallel to the rejuvenator content percentage in the mix. Besides, FTIR tests were conducted to find out the whether the rejuvenator effect had a chemical reaction (new chemical bonding) nature or it comes with some physical property modification in the mixture. The studied RAP was collected from the metropolitan area of the Montreal, and SYLVAROAD PR1000 commercial rejuvenator was used for the investigations.

Results indicated that although the rejuvenator content could significantly affect the clustering formation in the cold mix, the RAP content and its corresponding size as well as mixture preparation process (compaction and preparation temperature) had significant effect both on the cluster formation and rheological properties of the RAP such as tensile strength in IDT tests. In the case of new cluster formation in the rehabilitated materials, results showed that an increase in the rejuvenator content would result in an increase in the cluster formation. However, this effect was significantly increased when it was combined with the compaction. The same RAP IDT tests revealed that the optimum additive content is significantly affected by the preparation temperature where an increase in the specimen preparation temperature resulted in reduction in the required optimum content of rejuvenator (4% for specimen preparation at 40 ℃ and 7% for preparation at 60 ℃). Furthermore, rehabilitated extracted bitumen analysis showed that an increase in the rejuvenator content in the initial RAP could increase the low temperature and high temperature performance of the bitumen, however, the shear complex modulus suggested 7% additive percentage as the optimum content in this setup of materials. Finally, the chemical bonding analysis in the Fourier Transform Infrared Spectroscopy (FTIR) test could not reveal any effective chemical alteration/production in chemical functional groups of the tested materials as a result of rejuvenator addition in the rehabilitated extracted bitumen. In other words, results suggest that the rejuvenator effects are mostly controlled by the physical modification of the mix such as viscosity reduction, etc).


identifier: Jawarnenh, Ahlam  (2022). Hybrid massive MIMO architecture with SWIPT in NOMA systems.  Thèse de doctorat électronique, Montréal, École de technologie supérieure.

subject: récupération d’énergie

subject: onde millimétrique

subject: formation de faisceau hybride

subject: massifs MIMO

subject: gradient conjugué élargi à longue récurrence

subject: accès multiple non orthogonal

subject: la technologie de transmission simultanée d’informations et d’énergie sans fil

abstract: It is becoming apparent that radio frequency energy harvesting (EH) presents a vital potential for improving the energy efficiency of existing and future networks. EH has also emerged as a viable option, allowing for the re-use of a portion of the transmitted energy through an energy cycle. Moreover, the enormous need for large data speeds and increased traffic in wireless networks has prompted research into the millimeter wave (mm-Wave) spectrum for future (5G) communication systems. Massive antenna arrays are used for this high frequency. However, high implementation costs and signal processing complexity make completely digital (homogeneous) beamforming systems expensive and inefficient, while employing purely analog beamforming reduces system performance owing to hardware limits. To address the aforementioned issues, hybrid beamforming has been proposed. Finding an appropriate design remains a significant difficulty for the researcher. In this thesis, we first formulate and present a new method based on the long recurrence enlarged conjugate gradient (LRE-CG) algorithm for iteratively realizing the MMSE detection method while avoiding the matrix inversion complexities in massive MIMO systems. We demonstrate its superior performance to present competing methods. Then we tailor its application to massive MIMO systems and mmWave massive MIMO systems with NOMA System. It has been verified by the simulation results that the presented method outperforms the conventional methods in the literature including the Neumann series approximation-based approach and Gauss-Siedel iterative (GS) methods for massive MIMO systems. The proposed algorithm succeeds to attain the near-optimal performance of a typical MMSE algorithm with a minimal level of iterations. Secondly, we deal with the issue of power consumption in millimeter-wave (mmWave) huge MIMO systems caused by mixed-signal components like analog-to-digital converters. In order to increase the efficiency of the spectrum, we use non-orthogonal multiple access (NOMA) in mmWave large MIMO systems. Massive multi-input multi-output (MIMO) systems operating at millimeter waves will make advantage of the simultaneous wireless transmission of information and power (SWIPT). In the NOMA scenario, where inter-user interference may be utilized for energy harvesting, SWIPT is particularly helpful in extending the battery life of mobile users (MUs) and improving the system energy efficiency (EE) (EH). To begin with, we developed a user grouping algorithm based on affinity propagation clustering, which groups user equipment (UE) based on channel correlation and distance. Following that, we designed the analog RF precoder for all beams using the selected user grouping, then we designed a low-dimensional digital baseband precoder to achieve a maximum sum-rate as well as minimize inter-beam interference for the system. Afterward, we formed a joint power allocating and power splitting optimization problem. Given the existence of linked variables and inter-user interference, the studied non-convex optimization issue is challenging to handle. In order to address this issue, a decoupled approach is used, in which the power allocation and power splitting are treated as independent issues, and the Lagrangian duality technique is used to solve these sub-problems. The simulation findings validate the efficacy of the proposed technique and show that it is near-optimal and has superior spectrum and energy efficiency compared to the previous designs and the existing SWIPT-enabled mmWave MIMO-NOMA system.


identifier: Kazemmanesh, Alireza  (2022). A power management system for isolated operation of microbial fuel cells with voltage protection.  Mémoire de maîtrise électronique, Montréal, École de technologie supérieure.

subject: sources d’énergie renouvelable

subject: pile à combustible microbienne (PCM)

subject: système de gestion de l'énergie (PMS)

subject: suivi du point de puissance maximale (MPPT)

subject: commande en mode glissant (SMC)

abstract:
Renewable energy sources are growing rapidly in the world. In 2020, they made up 29% of all the electric power generated. Microbial fuel cell (MFC) is a high-potential energy source in this category. It helps remove environmental contaminants such those in wastewater, decrease carbon dioxide in the atmosphere, and convert organic substrates to electricity through a bioelectrochemical reaction.

However, due to its low power density, a single MFC cannot power most of common electronic applications. One solution to increase the power is to use multiple MFCs and connect them in parallel or series. However, these types of circuit configurations can result in overall lower power efficiency due to the unpredictable and unstable nature of MFCs.

This study aims to design a power management system (PMS) for harvesting the maximum energy from the MFCs in the stack. The PMS controls the connection and disconnection of the MFCs such that each MFC operates independently. Consequently, should there be an MFC failure leading to unwanted MFC disconnection, the energy harvesting process from the other MFC(s) continues without interruption. The PMS is developed to consider the biochemical limitation of microorganism in order to expand their lifetime. This was accomplished by employing an MFC health protection algorithm. This algorithm prevents the weak MFC to participate in the energy harvesting process. Control techniques such as hysteresis control and the maximum power point tracking (MPPT) are executed to achieve these contributions.

A high-efficiency DC-DC converter is selected as the back-end upconverter to boost the output voltage to a desirable level. The sliding mode controller (SMC), which is a voltage regulation (VReg) technique, is applied to the control of converter switching. The proposed controller maintains the output voltage of the converter within acceptable limits, regardless of the input voltage volatilities caused by the system nonlinearity. A two-level voltage reference was applied to the VReg technic to obtain higher levels of voltage and power at the load.

A testing procedure was constructed to evaluate the PMS performance based on the real-world MFCs characteristics. To make this happen, numerous lab experiments on four real MFCs were conducted and the extracted data was classified into three benchmarks. Each benchmark replicates the electrical characteristics of model-based MFCs according to their wide range of ambient and operational conditions. These benchmarks were applied to a comparable approach from a previous study and its pros and cons were compared to the proposed PMS.

The average load power (Ploadave) of 5.16 mW was obtained using the two-level VReg, which is 3.44 times more than utilizing the single-level VReg (1.5 mW). According to the PMS’s comparison results, the proposed PMS could successfully power the resistive load without interruption while multiple load power disruptions were observed in the previous study. Hence, the proposed PMS was reported to have a 41% higher Ploadave in this comparison in the case of multiple MFC failure

Further improvement upon this study can be including a start-up circuit to the converter for autonomous operation of the system, a necessary feature for using MFCs in remote areas.


identifier: Langevin, Antoine  (2022). Effective and scalable smart residential energy monitoring systems.  Thèse de doctorat électronique, Montréal, École de technologie supérieure.

subject: surveillance de la charge des appareils

subject: surveillance non intrusive de la charge

subject: séparation aveugle de sources

subject: autoencodeur variationnel

subject: prévision de la charge à court terme

abstract:
The growing interest for active end-user contribution in reducing the carbon footprint brings several new challenges that traditional solutions are insufficient to handle. In this collective effort, novel solutions, such as the accessibility of detailed information on users’ electrical energy consumption or the implementation of smart energy management systems, must be applied to achieve further energy savings. However, these solutions require effective and scalable methods to monitor the power consumption of appliances and predict household power demand while maintaining systems with limited intrusiveness and low cost.

In this thesis, we propose methods for appliance load monitoring (ALM) and household shortterm load forecasting (STLF). These methods are designed to address challenging problem characteristics that arise in real use cases. As an effective solution for demand response programs, semi-intrusive load monitoring (SILM) is used to get granular power measurements at the level of individual appliances in buildings. Hall effect sensors (HES) on each wire attached to a circuit breaker in distribution panels are one means of providing SILM. However, HES are greatly affected by crosstalk noise generated by neighboring wires, up to 35% of interfering signals. As a first contribution, we propose a blind source separation (BSS) approach to remove crosstalk noise and make SILM measurements accurate for home energy management systems. The proposed BSS approach is designed to deal with several challenging problems such as sparse mixing matrices, low mixing coefficients, and imbalanced signal levels. Experiments show that the proposed BSS approach achieves state-of-the-art performance, making the SILM a reliable low-cost alternative to intrusive ALM.

On the other hand, non-intrusive load monitoring (NILM) is a technique that uses a single sensor to measure the total power consumption of a building. Using an energy disaggregation method, the consumption of individual appliances can be estimated from the aggregate measurement. Recent energy disaggregation algorithms have significantly improved the performance of NILM systems. However, the generalization capability of these methods to different houses as well as the disaggregation of multi-state appliances are still major challenges. As a second contribution, we propose an energy disaggregation approach based on the variational autoencoders (VAE) framework. The probabilistic encoder makes this approach an efficient model for encoding information relevant to the reconstruction of the target appliance consumption. Experiments show that the proposed model accurately generates more complex load profiles, thus improving the power signal reconstruction of multi-state appliances. Moreover, the regularized latent space of the VAE framework strengthens the generalization capabilities of the model across different houses.

Finally, as a third contribution, we propose a two-stage approach for household STLF. However, the electrical load at the household level is highly impacted by user behavior. Hence, load forecasting at such a level of granularity is challenging due to the high uncertainty caused by the difficulty of expecting the user behavior. Therefore, the proposed approach leverages past and future appliance load information estimated from a NILM method. This granular information is then augmented through a household load predictive model. In the light of the experimental results on real-world data, identifying the running appliances as well as predicting their consumption is relevant information, and consequently has a significant impact on the performance of the household STLF.

This thesis shows challenges and solutions for monitoring and forecasting electricity consumption at a low granularity level in real use cases in buildings. We propose a SILM solution and a NILM solution to address some of these challenges for the ALM task. Moreover, we propose a STLF approach that leverages appliance load information to predict more accurately the household load demand. We validate all proposed methods on real-world data sets and identify future research directions and remaining problems.


identifier: Sabeti, Parham  (2022). Optimal temporal resolution for hydrological modeling studies.  Mémoire de maîtrise électronique, Montréal, École de technologie supérieure.

subject:
modélisation hydrologique
précision de la modélisation
résolution temporelle
taille du bassin versant

abstract: The impact of climate change on water resources has been an important field of research over the recent decades. Better water management is one way to adapt to a changing climate. To achieve this, having better rainfall-runoff models would be beneficial. Rainfall-runoff models are essential for improving our understanding and ability to forecast floods and droughts. Most hydrological modeling studies have been conducted at the daily-scale since most meteorological data was only available at this time step. However, higher temporal resolution data has become increasingly available at the sub-daily time scales. Previous work has shown that using data with a higher temporal resolution often results in an improvement in modelling accuracy. However, using a finer time scale increases the computational requirements of running the hydrological model. Finding the best time step is therefore an exercise in maximizing simulation accuracy while keeping the computational burden as low as possible. Smaller catchments may benefit more from a smaller time step due to the faster reaction time, whereas larger catchments may be relatively insensitive to the computation time-step. This highlights the importance of taking catchment size and shape into account when trying to determine the best temporal resolution. Even though there have been numerous studies on runoff models with sub-daily and even sub-hourly time steps, a systematic knowledge of how catchment size affects the time resolution option and how to determine the most efficient time step for the model has not yet been achieved. This work therefore investigated how the temporal resolution of a lumped hydrological model impacts simulation results, and if the impact is related to catchment size. Three-hundred and thirty-nine (339) catchments with quality-controlled hourly precipitation were selected covering most of the contiguous UnitedStates. Hourly meteorological data was aggregated at 2, 3, 4, 6, 12 and 24-hour time steps and one hydrological model was calibrated on all catchment and for each of the 8 time-steps. To study the impact of catchment size, the catchments were regrouped into 6 different size classes, from smaller than 500 km2 to larger than 4500 km2 , each group containing approximately the same number of catchments. Results showed that using as small a time-step as possible was beneficial to all catchment size classes, as it systematically improved the simulated flow bias as well as the magnitude and timing of peaks flows. The smallest size classes benefited the most from a reduced time step whereas for larger catchments, going to time step smaller than 8-hour only provided marginal improvements.


identifier: Shams, Nakisa  (2022). Low power agile wideband RF CMOS front-ends for 5G, Wi-Fi 6E and impulse radio applications.  Thèse de doctorat électronique, Montréal, École de technologie supérieure.

subject:
récepteur
sélection des harmoniques
suppression du bruit
IR-UWB
reconfgurable

abstract:
The 2020s belong to the ffth generation, 5G, that is a new radio (NR) standard, which is considered an outstanding evolution over the current communication systems and can be fexibly confgured for various application scenarios. Thus, our lives will be afected by 5G more dramatically than any other technology shift since it will lead us to a fully connected world. 5G using sub-6 GHz frequency band and millimeter wave (mm-Wave) spectrum together with other RF technologies like ultra-wideband (UWB) will provide multiple services.

As 5G NR transitioned from concept to reality, Wi-Fi has been the developing standard in parallel to keep it at par with the cellular standard providing better performance and higher throughput. Recently, the IEEE introduced a new task group, i.e., the Wi-Fi 6E or IEEE 802.11ax, to investigate and realize next-generation Wi-Fi technologies. Wi-Fi 6E refers to the set of Wi-Fi devices, provides gigabit throughputs with higher performance, faster data rates, and lower latency, and complements the deployment of 5G networks to provide connectivity indoors, where 5G NR is far less efective. Wi-Fi 6E was extended into the 6 GHz band, ofering considerable increases in available bandwidth. However, its relatively high power dissipation poses challenges for Wi-Fi being adopted for low power platforms, such as Internet-of-Things (IoT) devices and wireless sensor nodes. Forecasts of numerous connected devices by 2030 and the realization of 5G and Wi-Fi 6E drive the need for circuit-level techniques to alleviate the increasing interference coming with this growing number of devices.

To this end, this work focuses on design techniques to provide highly interference resilient RF receiver front-end architectures in a power efcient manner and operating in a wide range of input RF frequencies. First, a literature review is presented. It focuses on the RF receiver frontends, their transistor-level circuit, and their specifcations. In the second part of this dissertation, we demonstrate three wideband RF receivers using a 4-, 8-, and 16-path switching confguration that allows for the selection of the third harmonic of the local oscillator (LO) frequency, and that efectively suppresses other harmonics to reduce the input frequency and power consumption of the multi-phase clock generator at higher RF frequency bands of operation.

When considering the design challenges related to the N-path switching flter, including the number of switches, power consumption of the LO phases generation circuitry, and noise performance, it is shown that an 8-path switching flter system is preferred to provide a suitable trade-of between the harmonic fold back efects, noise fgure, circuit area, and power consumption. Thus, the third part of this dissertation demonstrates a blocker-tolerant harmonic selection wideband RF receiver that can be reconfgured to select the frst and third harmonics of the switching frequency at the low and high frequency bands, respectively. We present a proof of concept integrated circuit in 130 nm CMOS technology process and present the measurement results.

Strong out-of-band (OOB) interference or undesired blockers can desensitize a receiver. To enhance resilience to the blockers, the RF front-end must avoid amplifcation at blocker frequencies at the input node of the receiver. To do this, two diferent wideband noise-cancelling wideband RF receiver architectures are then presented that have the capability of tolerating the LO harmonic blockers without sacrifcing noise performance and alleviating the SAW pre-flters requirement while consuming low clocking power consumption. Measurement results from the integrated circuit prototypes in 65 nm CMOS confrm our techniques’ benefts.

Since power dissipation is always important for wideband communication devices, more power can be saved by exploiting a self-demodulating direct conversion impulse radio UWB (IRUWB) architecture. To this end, this dissertation describes the study, design, fabrication, and characterization of a reconfgurable dual-band non-coherent wideband IR-UWB front-end. The proposed multi-band IR-UWB receiver can be digitally reconfgured in diferent operating frequency modes, and is able to support data modulated in binary frequency shift keying (FSK) in addition to on-of keying (OOK), and allows for the leveraging of ternary signaling by combining both OOK and FSK modulations. Ultimately, a detailed design methodology and measurement results of the fabricated receiver in TSMC 130 nm CMOS technology are presented.

The presented techniques will undoubtedly allow the development of new applications, and will thus contribute to the scientifc knowledge advancement on RF wideband receiver front-ends.


identifier: Dourandish, Simin  (2022). Microstructure-based process modeling of open die forging of a high strength martensitic stainless steel.  Thèse de doctorat électronique, Montréal, École de technologie supérieure.

subject:
acier inoxydable martensitique
déformation à chaud
simulation d’éléments finis
évolution microstructure
forgeage de lingots de grande taille
recristallisation dynamique
analyse des dommages
équation constitutive
modélisation de matériaux

abstract:
In engineering components, high-strength stainless steels are well known for their corrosion resistance and excellent combination of strength and toughness. Heat treatment can change their properties and make them suitable for a variety of applications such as offshore platforms for oil extraction, cutting tools, steam generators, pressure vessels, and blades. Manufacturing of these large components starts with the sequence of casting, forging, quenching, and tempering operations. The main aim of forging the as-cast ingot is to eliminate the casting defects that occur during solidification including shrinkage, segregation, porosity, non-metallic inclusion, and cracks. These defects are initiated during the teeming of the liquid steel and/or during solidification in the mold. Although casting process optimization has been used to reduce the incidence of these defects, preventing them is very difficult. A detrimental defect causes heterogeneous properties in the final cast ingot, which significantly affects the performance and suitability of the final products. However, if the defects are too big, it is very difficult to heal all the porosity just by the forward forging process. As a result, the appropriate and accurate forging schedule is significant for heavy manufacturing industries. It is the main purpose of this work to examine the mechanisms involved in the microstructural evolution of a martensitic stainless steel used in oil and gas industries as a turbine shaft during the breakdown of the as-cast structure. In addition, the hot deformation behavior of the investigated steel was modeled using the best predictable material model. Using a finite element code, the constitutive equations and microstructure evolution models are implemented, and then thermomechanical and microstructure evolution are coupled.

The first part of this study provides the microstructure characterization of casting structures during solidification. Advanced characterization techniques were used to determine the phase distribution, chemical composition, and phase identification. All determining factors were considered to investigate the occurrence of phase precipitation and segregation during the casting process.

The second part of this study is focused on isothermal hot compression tests using the thermomechanical simulator machine, Gleeble TM 3800, in order to determine the flow behavior of the investigated martensitic stainless steel under a wide range of temperatures and strain rates corresponding to the industrial forging process for large size ingots. The measured flow stresses were corrected by considering the effect of friction and adiabatic heating and then used to develop a model in order to predict the flow behavior of the material. The mathematical equations that best predict the flow curves model were established and the accuracy of the developed material model was verified with experimental measurements.

Heavy forging is a highly nonlinear process in which plastic deformation and recrystallization change both the microstructure and the boundary conditions. In hot forging, microstructure evolution impacts deformation behaviors due to its effects on dynamic recovery, dynamic recrystallization, and grain growth. At the same time, forging parameters such as strain, strain rate, temperature, and pass sequence control microstructure evolution. Therefore, the third part of this project was allocated to investigating the effect of working parameters on microstructure evolution during the hot forging of martensitic stainless steel. After experimental analysis of microstructure evolution, the mathematical equations which describe the microstructure changes were developed.

The next step was integrating the constitutive equations and microstructure models into a 3D finite element code to predict the variations of strain, dynamic recrystallization fraction, DRX grain size, and damage. The most important criterion in the forging industry is to determine the deformation conditions at which the ingot is susceptible to cracking and failure of the component. Therefore, the prediction of the risky deformation conditions or areas of the component is of great importance.

After the validation of all models, the forging process of a 13.5-ton ingot was simulated by the developed system based on industrial operational practice. The influence of working parameters including temperature, strain, and strain rate on microstructure evolution was analyzed. Simulation of the forging process has been used to analyze strain, temperature, dynamic recrystallization volume fraction, and grain size variations. Based on the developed simulation system, an optimum hot forging process was designed.


identifier: Lavertu, Jean-Simon  (2023). Détection de défauts de surface sur le bois par capteur tactile capacitif.  Mémoire de maîtrise électronique, Montréal, École de technologie supérieure.

subject:
capteurs tactiles
inspection de surface
détection de défaut
apprentissage profond

abstract:
La montée en popularité des robots collaboratifs crée, pour plusieurs petites et moyennes entreprises, de nouvelles possibilités d’automatisation qui n’étaient pas auparavant viables. C’est notamment le cas pour l’inspection de tâches de sablage et de polissage de produits en bois. Or, afin de pouvoir réaliser cette inspection, le robot doit être équipé de capteurs permettant de percevoir les détails de leur surface. Dans ce mémoire, nous avons exploré la possibilité d’utiliser un capteur tactile capacitif pour détecter la présence de défauts de surface sur le bois.

Dans un premier temps, nous avons utilisé les quatre modalités du capteur tactile CoRo pour entraîner une variété de réseaux de neurones artificiels à détecter la présence de trois types de défauts de surface, soit les rayures, les indentations et les arrachements. Aucune des modalités n’a permis de détecter la présence de rayures étant donné leurs très petites dimensions. Cela dit, la modalité statique, qui mesure le motif de pression sur la surface du capteur, a obtenu les meilleurs résultats pour les indentations et les arrachements.

Nous avons ensuite testé si la fusion des modalités permet de mieux détecter la présence de défauts. Contrairement à ce que nous avions anticipé, les résultats obtenus montrent que la fusion ne permet pas nécessairement d’obtenir une meilleure performance que l’utilisation de modalités individuelles. Néanmoins, nous avons confirmé que la modalité statique, utilisée seule ou en combinaison avec la modalité dynamique, est la plus intéressante.

En somme, nous avons démontré que le capteur tactile capacitif CoRo représente une solution prometteuse pour la détection de défauts de surface dans le bois. Toutefois, sa conception devrait être repensée en fonction de cette tâche pour atteindre le maximum de performance.


identifier: Tonga Naha, Rodrigue  (2022). Pupa: Moteur de génération des contrats intelligents pour les processus d’affaires avec évènement de minuterie et branchement inclusif.  Mémoire de maîtrise électronique, Montréal, École de technologie supérieure.

subject:
chaîne de blocs
business process management
contrat intelligent
BPMN
événement de minuterie
branchement inclusif

abstract:
La chaîne de blocs et les autres registres distribués sont reconnus comme des technologies clés aptes à offrir des propriétés de confiance et de transparence. À cet effet, un besoin en matière d’applications décentralisées et capables de déployer les processus d’affaires sur les contrats intelligents se pose. Les solutions existantes de BPM basées sur la chaîne de blocs, prennent en charge diverses plateformes de chaîne de blocs (exemple Ethereum) et différents langages de modélisation de processus (exemple BPMN).

Cependant, à cause des limitations liées à la programmation des contrats intelligents notamment l’impossibilité de planifier l’exécution d’une transaction, la majorité de ces approches ne soutient pas les processus métiers avec les évènements de minuterie et décisions inclusives. Afin de renverser les défis mentionnés ci-dessus, nous proposons un moteur logiciel appelé Pupa. Pupa est une solution décentralisée basée sur Ethereum capable de convertir les processus d’affaires avec évènement de minuterie et branchement inclusif en contrat intelligent.

Pour réaliser ce service, notre solution ajoute les fonctionnalités de la tâche utilisateur à l’évènement de minuterie et augmente des procédures de contrôle sur la tâche succédant la minuterie. De plus, la solution Pupa implémente des variables d’écoute sur les flux de séquence des branchements inclusifs. Nous avons implémenté notre solution en allongeant la solution Caterpillar. C’est une solution BPMN existante qui utilise Solidity et Ethereum. Nous avons évalué les performances de Pupa et nous l’avons comparée à celle de Caterpillar. Nos résultats montrent que Pupa, en plus de supporter des éléments additionnels de BPMN, est assez performante en termes de coût de déploiement et de nombre de lignes du code généré.


identifier: Cunningham, Nicholas  (2022). Injectable chitosan hydrogel as a delivery system for cancer immunotherapy.  Thèse de doctorat électronique, Montréal, École de technologie supérieure.

subject:
adoptive cell therapy
immunothérapie du cancer
chitosane
hydrogel
injectable
études animales
modèles de tumeur
microbilles

abstract:
Adoptive cell therapy (ACT) is a cancer immunotherapy where high quantities of T cells that specifically target cancer cells are administered intravenously to patients, where the delivered cytotoxic CD8+ T cells can directly eliminate cancer cells. In various forms, it has shown success against previously treatment-resistant cancers such as metastatic melanoma and certain blood cancers, though its use is often limited in solid cancers. Despite its success, limitations persist including the difficulty of cultivating the high number of cells required, their dispersal to non-tumour sites and side effects resulting from the drugs necessary in clinical ACT.

Localised delivery of T cells, for example via a scaffold, could address these limitations by concentrating cells at the tumour site, reducing both the initial number of cells and the dosage of associated drugs required for successful treatment. An ideal scaffold for this application should be easily administered and mixed with cells, biodegradable and biocompatible with encapsulated cells, allowing them to perform their anti-cancer function. The hypothesis of this PhD is that localised delivery will allow treatment with fewer cells and greater efficacy than systemic treatment.

The thermosensitive chitosan hydrogel that we have developed was shown to be biocompatible and biodegradable in vivo, and supported the survival, escape and anti-cancer functionality of encapsulated T cells. In the MC38-OVA murine tumour model, gel-encapsulated OT-I limited tumour growth compared to untreated and mice treated with PBS-suspended OT-I, though IVdelivered OT-I were more effective than the gel in limiting tumour growth. This showed the feasibility and potential of the chitosan gel for localised OT-I delivery as a cancer immunotherapy. Microbeads were successfully produced as an alternative gel format to potentially improve oxygen and nutrient access to encapsulated cells, although their fabrication must be optimized due to the currently elevated mortality in microbead-encapsulated cells. Further development of the microbeads, as well as the addition of growth factors and binding motifs, could further improve gel efficacy and continue progress towards eventual clinical translation.


identifier: Villeneuve, Guillaume  (2022). Développement d’une machine et du contrôle d’un procédé d’usinage électrochimique pour matériaux difficiles à usiner.  Mémoire de maîtrise électronique, Montréal, École de technologie supérieure.

subject:
micro-usinage
verre
systèmes micro-électromécanmiques

abstract:
Ce mémoire a pour but de faire des avancements dans le développement d’un procédé d’usinage électrochimique, la gravure chimique assistée par étincelage (Spark-Assisted Chemical Engraving, SACE). Le procédé SACE a des applications particulièrement pour la fabrication de formes à l’échelle des dizaines aux centaines de micromètres dans des matériaux durs et fragiles. Notamment, le verre, qui sera le cas à l’étude, est utilisé dans les systèmes micro-électromécaniques et microfluidiques.

Le SACE est présentement un procédé académique, avec peu d’adoption en industrie. Ceci est dû à un manque de contrôle sur le procédé, menant à une mauvaise répétabilité des formes usinées. L’objectif principal de ce projet de recherche est l’identification d’un signal de rétroaction permettant un meilleur contrôle sur le procédé. La mesure du courant électrique passant par les électrodes est un bon candidat, et sera étudiée ici.

Premièrement, la littérature en micro-usinage du verre a été revue. La niche que pourrait occuper le SACE dans l’industrie a été identifiée, principalement dans le contexte de prototypage rapide et production en petite série. Ensuite, l’état de l’art du SACE a été étudié. Les enjeux actuels ont été identifiés et des avenues de recherche pertinentes permettant d’améliorer le procédé et son adoption en industrie ont été proposés.

Deuxièmement, deux machines SACE ont été conçues et développées. La première, ayant une très bonne précision de positionnement, offre de nombreuses avenues de recherche par sa flexibilité et facilité d’interface. Le système de contrôle de celle-ci a été programmé, incluant un module pour AutoCAD permettant la création de parcours d’outil spline. La seconde, simple et à faible coût, a permis de faire des essais à faible délai. Elle a été conçue et fabriquée à base d’une fraiseuse de bureau à commande numérique.

Finalement, une étude a été complétée et soumise à une revue scientifique avec comme objet l’utilisation du signal de courant en usinage SACE. Des opérations SACE de base ont été exécutées avec la machine à faible-coût. Deux applications ont été proposées : un palpage sans contact, en profitant d’un pic dans le courant à l’approche de l’outil, et puis un monitorage de l’état du film gazeux entourant l’outil, ce qui affecterait la stabilité des décharges et l’uniformité de l’enlèvement de matière.


identifier: Aouinti, Meriam  (2023). Sorption du produit de traitement de bois par l'argile dans la construction en terre : cas de l'octaborate disodique tétrahydraté (DOT).  Mémoire de maîtrise électronique, Montréal, École de technologie supérieure.

subject: sapin

subject: épinette

subject: octaborate disodique tétrahydraté (ODT)

subject: torchis

subject: durabilité

subject: protection biologique et contre le feu

subject: architecture écologique

abstract: L'utilisation de la construction en terre crue est idéale pour l’architecture écologique car elle a un impact environnemental positif. Le torchis représente la méthode et le matériau de remplissage d'une structure en bois. Pour pouvoir supporter la charge des bâtiments, il doit avoir une capacité puissante. Le bois utilisé dans ce projet a été traité avec l'octaborate disodique tétrahydraté DOT, qui offre la capacité de protéger à la fois du feu et des agents de détérioration biologiques. Le but ultime de cette étude est d’évaluer la capacité du bois à conserver la durabilité accordée au contact avec le torchis en fonction du temps, du pourcentage d’humidité, des essences de bois (épinette et sapin), et de l’axe de remplissage. Les résultats en fonction de temps montrent un profil de mouvement DOT décroissant dans l’argile allant de la partie en contact avec le bois vers la surface. Ce profil disparaît généralement si un contact dure plus de deux mois. L’expérience à long terme a montré que la quantité de DOT sorbée a tendance à se stabiliser avec le temps même si la concentration initiale de DOT est différente. Les résultats en fonction de l’humidité de conditionnement (9 et 19 %) montrent que cette dernière n’a pas un effet significatif sur la quantité de DOT sorbée par l’argile. Afin d’identifier les différentes phases présentes et de déterminer les changements microstructuraux provoqués par le traitement et le contact avec l’argile, une étude spectroscopique a été menée sur quelques échantillons de bois traités avec et sans contact avec l’argile ainsi que sur certains échantillons de bois non traités. À partir de cette étude, nous n’avons pas pu détecter la présence du bore sur le sapin de façon statistiquement significative alors que les résultats pour l’épinette nous ont permis d’identifier le mécanisme de fonctionnement de l’argile sur le bois.


identifier: Benesch, Danielle  (2022). The sensitive ear: towards real-time monitoring of in-ear physiological and audio signals for managing decreased sound tolerance.  Mémoire de maîtrise électronique, Montréal, École de technologie supérieure.

subject:
tolérance sonore réduite
appareils auditifs
reconnaissance automatique du stress

abstract:
People with decreased sound tolerance often wear hearing protection or headphones to block out the sounds they are sensitive to. However, conventional hearing devices indiscriminately block out all sounds, even when these sounds do not cause distress and may be useful for the wearer to hear. The resulting acoustic isolation can prevent the wearer from fully participating in their environment and could also have long term consequences, as research suggests that regular noise avoidance may exacerbate sensitivity to sound. A potential solution to over-avoidance of noise could be a hearing device specifically designed for decreased sound tolerance to attenuate sound only when necessary to reduce the wearer’s stress, by recording external sounds, processing them, and selectively transmitting them inside the earcanal.

However, there are several challenges associated with developing a hearing device that selectively attenuates distressing sounds: 1) Existing devices used to manage decreased sound tolerance are not readily modifiable, and the resources required to independently develop a new device can be a barrier to prototyping new features; 2) There is limited research on how to balance usability considerations such as how effectively distressing sounds are filtered out and potential impacts on speech comprehension, which could be of particular concern for populations where decreased sound tolerance symptoms co-occur with communication challenges; 3) The presentation of decreased sound tolerance can vary greatly, for different individuals as well as over time for the same individual, and therefore, the audio processing required could depend on each wearer’s current needs.

This thesis presents the findings of research efforts aiming to address the above challenges: First, existing hardware and software tools to prototype hearing device algorithms were evaluated for their suitability for decreased sound tolerance research. A processing pipeline interfacing an external personal computer with a microcontroller-based platform was developed to allow for algorithms implemented on the computer to control real-time audio processing. Second, an experimental protocol, piloted online with 50 participants, was developed to assess the latency requirements for real time audio processing based on how simulated delays affected a task necessitating speech comprehension. Third, with a dataset of 30 participants’ heartbeat sounds recorded from a hearing device during a stress-induction protocol, an automatic stress recognition system was developed and validated. These results open the possibility for a hearing device that can adapt to the wearer by simultaneously monitoring stress and controlling triggering noise for the benefit of users with decreased sound tolerances.


identifier: Kolahdouz Moghaddam, Amir Reza  (2022). Temperature Compensation and Performance Enhancement Techniques for Lamé Mode MEMS Resonators.  Mémoire de maîtrise électronique, Montréal, École de technologie supérieure.

subject: résonateurs MEMS

subject: micro-usinage en masse

subject: caractérisation du comportement résonant

subject: coefficient de température de fréquence

subject: résonateur compensé en température

subject: fermeture d’entrefer

subject: électrode mobile

subject: résistance motionnelle

abstract:
The importance of micromachined resonators continues to grow as they become increasingly prevalent in a wide range of applications, from wearable devices to more complex applications such as wireless communication and aerospace. As a result of this increased demand, academics and industry are developing oscillators with higher performance and stability while focusing on cost reduction.

Although numerous resonator architectures and electrical circuits to drive the resonator have been studied for many years, the problem of producing a fully compensated resonator that operates independently of ambient temperature remains unsolved.

This work presents an analytical model for predicting the performance of a Lamé resonator with varying rotation angles, and different structure varieties are proposed. The adaptability of the proposed analytical model is demonstrated, and the model’s versatility is experimentally validated by fabricating multiple resonator variants and analyzing their frequency responses and temperature behavior.

Afterward, a novel Lamé mode electrostatic resonator employing a chevron-shaped thermal actuator is proposed, which decreases the transducer gap resulting in a reduced motional resistance and overcoming the micro-fabrication process limitation in the minimum spacing of the structural silicon layer. It is shown that combining the heaters and the resonator in a small area may result in frequency stability over temperature by applying the ovenization concept utilized in oscillators.


identifier: Pourvali Kakhki, Amin  (2022). A low-power agile coherent IR-UWB receiver with non-coherent-assisted synchronization.  Mémoire de maîtrise électronique, Montréal, École de technologie supérieure.

subject:
ultra-wideband
impulse radio
coherent
non-coherent
synchronization
low power
template-based correlation

abstract:
Impulse Radio Ultra Wide Band (IR-UWB) has recently received significant attention for short-range wireless communication applications. The unique properties of IR-UWB systems have made them more prevalent in today’s wearable and Internet of Things (IoT), sensor nodes, healthcare devices and smartphones.

A variety of transceiver architectures in the IR-UWB system have been proposed by researchers over the past decade, including coherent and non-coherent architectures, which can improve one or more challenges associated with the IR-UWB systems. This thesis aims to realize a low-power efficient coherent IR-UWB system. In order to reduce the energy consumption of conventional coherent receivers, a hybrid synchronization algorithm for the coherent receivers is proposed. Prior to a coherent synchronization, the algorithm uses a non-coherent assisted synchronization to limit the search space. Compared to conventional coherent receivers, this method greatly reduces the amount of power used for receiver synchronization.

The proposed hybrid synchronization method begins with a non-coherent synchronization mechanism based on energy detection using On-Off Keying (OOK) modulation to coarsely synchronize the receiver by determining the correct integration window in which the received signal resides. Once the coarse synchronization level is achieved, a coherent template-based coherent correlation employing Binary Phase-Shift Keying (BPSK) modulation is carried-out for fine synchronization and to benefit from coherent payload decoding.

A prototype IR-UWB receiver operating from 3.5 to 5 GHz has been implemented in a TSMC 65 nm CMOS technology. Our proposed receiver architecture enabled us to compare our hybrid synchronization approach to two common receiver architectures, namely non-coherent energy detection and coherent detection receivers.

The receiver architecture utilizes a self-mixer for a non-coherent detection based on OOK modulation and a template correlation for a coherent detection based on BPSK modulation. Most blocks in the proposed receiver architecture, including the LNA, mixer and baseband circuitry are shared between the non-coherent and coherent modes to minimize the total power consumption and receiver area. A two-step coarse and fine acquisition mechanism is utilized to simplify the coherent synchronization and minimize the total required packet length. A multi-resolution Delay-Locked Loop (DLL) and a fast start-up Voltage Controlled Oscillator (VCO) provide the proper phase for the integration window and template generation.

The receiver consumes 6.8 mW in non-coherent mode and 8.8 mW in coherent mode when operating fully ON, excluding the power consumption of the buffers and the digital baseband processor. It achieves a -68 dBm, -70.5 dBm, and -70.8 dBm RF sensitivity at a 10−3 BER in the non-coherent, coherent, and proposed hybrid mode, respectively. Our proposed receiver architecture, in combination with the hybrid coherent synchronization algorithm, demonstrates that the proposed synchronization approach is capable of significantly reducing the overhead incurred by the preamble. The packet duration is reduced from 37.12 us dans le cas de corrélation cohérente à 24,42 us avec la méthode de synchronisation hybride proposée pour une charge utile de 1024 bits.


identifier: Rossignol, Chantal  (2022). A two-step strategy to reduce garment volumes and improve garment structural fit for everyone.  Mémoire de maîtrise électronique, Montréal, École de technologie supérieure.

subject:
mode
vêtement
garde-robe
ajustement
sur mesure
automatisation
environnement

abstract: This research elaborated a two-step strategy to reduce garment volumes and improve garment structural fit for everyone. The strategy is based on data from semi-structured discussions and a comprehensive literature review. Step 1 is a conceptual concerted minimal custom wardrobe model that is composed of a minimal number of custom garments that structurally fit a person’s unique body shape and are concerted to efficiently relate to one another and, over an extended period of time, to the person’s unique style, social and climate profiles. Step 2 is the automation of custom structural fit. That is, the ability of a computer-aided design (CAD) system to draft, for each and every body shape and directly from inputted formulas and body shape data, patterns that structurally fit without alterations. Such automation gives more people, professionals, and companies the ability to create, with less skills and training, custom garments that structurally fit, scaling the potential effect of the concerted minimal custom wardrobe on garment volumes, and user satisfaction and agency. However, this research established that CAD systems and existing research do not truly automate optimal custom structural fit, in part because with multiple gaps, pattern drafting does not produce for each and every body shape, optimal structural fit that does not require alterations. For these reasons, studies on the topic of custom pattern drafting CAD systems were analysed to identify priority topics for subsequent research. They are, automation of custom block patterns that structurally fit, complete body shape data from 3D body scans and expert structural fit evaluation.


identifier: Noei Yazdian, Mehrdad  (2023). A correlation-based algebraic transition model for flow over rough surfaces.  Mémoire de maîtrise électronique, Montréal, École de technologie supérieure.

subject:
rugosité
turbulence
SA-BCM
profil givré
transition laminaire/turbulente

abstract: The problem of icing is one of the challenges in the aviation industry which has not been tackled completely. Aircraft icing can affect flight safety in many ways. When the aircraft undergoes icing, due to the changes in the shape and roughness of the surface, the maximum lift coefficient, critical stall speed and slope of the lift curve decrease, while the drag increase. Rough surfaces, such as ice, cause the transition onset location to move upstream and the flow becomes turbulent at lower Reynolds numbers. Since in turbulent flow, the cooling effect increases significantly compared to laminar flow, it is important to locate the onset of the transition for ice accretion simulation. Several Reynolds-averaged Navier-Stokes transition models exist; However, they were mostly developed over smooth surfaces. For further development over rough surfaces, the SA-BCM (Spalart-Allmaras Bas-Çakmakçıoğlu with Modifications) transition model was adopted. The SA-BCM transition model is classified as an algebraic or zero-equation model since it employs an intermittency function rather than deriving additional equations for intermittency transport. The underlying model for the SABCM transition model is the well-established and validated Spalart-Allmaras (SA) turbulence model. To detect the transition onset location, the turbulence production term of the SA model has been damped with an intermittency function until it satisfies a turbulence onset criteria using empirical correlations. First, the experimental results from literature over rough flat plate were utilised as a reference to further develop the SA-BCM model to account for surface roughness. In this experiment, the effect of different roughness heights on the transition onset location at a constant free stream velocity has been studied and documented. The empirical correlation mentioned previously has been modified to mimic the same transition location as the experimental results. The model was calibrated against a flat plate with a zero-pressure gradient and various equivalent sand-grain roughness heights. In the next step, the NACA0012 airfoil has been chosen to validate the roughness correlation. The validation is done using the same geometry and two Reynolds numbers. The model was able to set the transition point in between the transition region compared to the experimental and other CFD results. However, it was unable to exactly predict the transition onset location and the end of the transition region.


identifier: Palmieri, Sébastien  (2022). Nouvelle stratégie d’insertion haute vitesse basée sur l’inclinaison en robotique collaborative.  Mémoire de maîtrise électronique, Montréal, École de technologie supérieure.

subject:
insertion en robotique
robotique collaborative

abstract:
Lors de cette maîtrise, nous avons contribué à la recherche en assemblage pour la robotique collaborative par la conceptualisation et réalisation d’une nouvelle stratégie d’insertion basée sur le principe de l’inclinaison. Son effet sur les forces et positions du robot a permis d’élaborer un vecteur solution, candidat à une direction vers un alésage dont la position est initialement inconnue.

Les insertions ont été analysées minutieusement pour aider le robot dans la recherche de trou et éliminer l’effet de hasard de l’insertion en spirale. Ceci a rendu le robot plus intelligent sans avoir à utiliser un système de contrôle rigide ou un capteur externe.

Nous avons pu effectuer l’insertion de nombreux types de chevilles, telles que des matériaux différents, des diamètres différents et longueurs différentes avec des performances qui dépassent ce qui se trouve sur le marché.


identifier: Remila, Kamilia  (2023). La démarche participative du projet Dow : une étude de cas.  Mémoire de maîtrise électronique, Montréal, École de technologie supérieure.

subject:
définition du projet
valeur
utilisateur
lean
besoins
exigences

abstract:
La définition du projet est la toute première phase d’un projet de construction. Il s’agit d’un processus visant à déterminer et à recueillir les besoins, les souhaits et les attentes du client pour un ouvrage. En d’autres termes, la définition d’un projet conduit à énoncer le problème architectural et les exigences à satisfaire. Elle est considérée comme l’une des principales contributrices à la valeur dans le cycle de vie du projet. En effet, de nombreuses caractéristiques d’un projet sont désignées à cette étape.

Beaucoup de problèmes liés aux projets de construction sont attribués à l’inefficacité de cette phase. L’une des principales causes avancées est la faible implication des utilisateurs. En outre, dans une démarche traditionnelle de définition d’un projet, les besoins ou les exigences du client sont déterminés avant le développement de la conception. Cette approche était adéquate à une époque où la plupart des institutions étaient plus simples et lentes à changer. Cela permettait aux architectes de comprendre intuitivement ce dont ils avaient besoin. Elle est devenue obsolète à mesure que les projets se sont complexifiés. Des approches participatives, dans lesquelles l’ensemble des usagers sont impliqués, sont proposées pour pallier ces problèmes. Toutefois, la littérature informe peu sur l’apport de ces approches à la définition du projet par rapport à l’approche traditionnelle. Ainsi, notre recherche s’applique à apporter un éclairage sur cet aspect.

Notre méthodologie de recherche s’appuie sur deux études de cas exploratoires : le premier cas est réalisé selon une approche traditionnelle, tandis que le second est réalisé avec une approche participative, suivi d’une étude de cas approfondie dont la définition de projet est réalisée selon les deux approches. Cette recherche permet alors d’identifier les écarts entre la définition traditionnelle et participative d’un projet, et ce notamment au niveau des enjeux des programmes complexes et évolutifs. Ensuite, elle identifie les barrières de l’application de cette approche en les comparant aux deux études de cas exploratoires.

Connaissant ces écarts et ces barrières, les professionnels qui entreprendront l’application de l’approche participative ; auront une meilleure connaissance de la valeur ajoutée de celle-ci et pourront anticiper les barrières susceptibles d’être rencontrées lors de son utilisation.


identifier: Dawa, Mohamed  (2022). Design and analysis of chaos-based communication systems.  Thèse de doctorat électronique, Montréal, École de technologie supérieure.

subject:
5G
Internet des Objets
DCSK
TEB
FTN

abstract:
The introduction of the IoT paradigm for shaping the future 5G network, as billions of new devices would be deployed with different needs in terms of wireless access, is one of the cornerstones in establishing the 5G standard. A large chunk of the IoT network consists of the WSN and LOWPAN devices, known as devices with limited computation and battery life resources. The new standard for IoT devices, i.e., 802.15.4aa specifies several physical layer methods of access for the Low-Rate Wireless Networks using modulations like DSSS, FSK, MPSK, and UWB. The more significant proportion still deploys the DSSS modulation for WSNs, given its excellent performance in terms of security and its simple implementation.

The chaos-based modulations offer better performances in comparison with the DSSS and were considered in the literature, given the excellent statistical properties of the chaotic signals. Hence, they were considered an alternative, especially for devices with low capabilities widely seen in WSNs and LOWPANs. The non-coherent chaos-based scheme specifically offers an excellent solution with its simple detection method that enables successful transmission even through very noisy channels and multipath fading.

In the literature, the BER performance of non-coherent chaos-based schemes lacks a universal approach in its establishment, given that every scheme is studied apart and its BER performance is computed using Monte Carlo simulations or through the error function for each model. Moreover, the inherent limitation of non-coherent chaos-based systems in terms of data rate and spectral efficiency has been tackled by introducing countless modulation schemes. However, most of the schemes proposed in the literature require advanced signal processing blocks to implement such designs.

In light of this, the issue of BER computation is tackled in the second chapter of this thesis, where the BER expressions of several non-coherent chaos-based schemes over the multipath Rayleigh fading channel are studied, and a new metric in the form of a lower bound is introduced. For this purpose, a transformation is applied to the BER expression of non-coherent chaos-based schemes to replace the error function with an equivalent lower bound to the exponential function multiplied by the PDF of the fading channel, and then an anti-derivative is calculated. This yields a true theoretical expression that can be used to accurately compute the BER values over multipath Rayleigh fading channels for different chaos-based systems

As a follow-up, the third chapter extends the work done in chapter 2 to a more generalized channel model, namely the multipath Nakagami-m fading channel. The same methodology is applied to the non-coherent chaos-based models in order to derive a closed-form solution of the BER expression. The newly established lower bound to the BER is then computed and compared to the simulation results and proven to deliver a close match with tiny performance gaps.

The fourth chapter of the thesis is dedicated to the improvement of the spectral efficiency of the basic DCSK design. Since the DCSK scheme suffers from the transmission of a reference signal that actively occupies half of the transmission time, we opt for a solution that can shorten such time. We combine the DCSK design with the FTN filtering to reduce the spacing between the transmitted symbols and as a result obtain a gain in terms of spectrum usage. The performances of the newly introduced design are evaluated for different channel models and system settings. In addition, the system performances are compared to state-of-the-art designs in terms of BER and spectral efficiency.


identifier: Agossou, Coffi Dominique  (2000). Dynamique des populations des régions métropolitaines et non métropolitaines du Canada : une approche multirégionale.  Thèse.  Québec, Université du Québec, Institut national de la recherche scientifique, Doctorat en études urbaines, 302 p.

type:
Thèse
Non évalué par les pairs

subject:
Population
dynamique
démographie
accroissement
évolution
migration
immigration
ville
région
région métropolitaine
territoire
Canada
projection
analyse multirégionale.

abstract:
Le présent travail examine les mécanismes démographiques selon lesquels les régions métropolitaines de recensement (RMR) et les régions non métropolitaines (RNM) du Canada ont évolué au cours des vingt-cinq dernières années et évolueront dans le futur. L'approche multirégionale de A. Rogers nous a servi de base théorique pour atteindre ce
but. L'intérêt de cette approche réside dans le fait qu'elle permet d'examiner de façon jointe et simultanée non seulement les 25 RMR et 10 RNM, mais aussi la fécondité, la
mortalité et la migration. Pour chacune des 35 régions, nous avons dans une première étape analysé l'évolution de
la taille et de la structure par âge des populations, de la fécondité, la mortalité, la migration interne et la migration internationale entre 1971 et 1996. Il ressort
fondamentalement de cette analyse qu'il existe des disparités marquantes non seulement entre RMR et RNM mais aussi entre les régions métropolitaines elles-mêmes, et cela
quelle que soit la composante démographique considérée.
En 1971, 57% de la population canadienne habitait les régions métropolitaines mais en 1996, cette part des RMR est passée à 62% et corrélativement les RNM ont perdu de leur poids. Ce sont surtout Toronto, Montréal, Vancouver et Ottawa-Hull qui continuent d'attirer une bonne part de la population du pays. La croissance de la population dans ces
régions est relativement rapide. La croissance de la population des RMR et surtout des grandes régions s'explique de plus en plus par l'immigration internationale qui continue de se concentrer à Toronto, Vancouver et Montréal. Ainsi, en général on observe qu'aussi bien dans les RMR que les RNM, le rôle de l'accroissement naturel dans l'accroissement total de la population baisse alors que celui de la migration augmente. La population vieillit plus rapidement en RNM qu'en RMR; dans ces dernières le
processus de vieillissement est ralenti par l'immigration internationale mais cet effet de rajeunissement est très faible. L'indice synthétique de fécondité est en baisse dans toutes les régions, la baisse étant plus rapide dans les RMR que les RNM. L'âge moyen à la maternité augmente dans toutes les régions, cela signifie que les femmes ont tendance à reporter leurs naissances. Cette tendance est plus forte en RMR et surtout en grandes régions. L'espérance de vie est en hausse aussi bien en RMR qu'en RNM; cependant un enfant né dans une région métropolitaine vivra plus longtemps que le nouvau-né d'une RNM. Les jeunes adultes (15-29 ans) ont une propension à sortir plus élevée en RNM qu'en RMR. Les migrants en provenance des RMR ont un âge moyen relativement plus élevé que ceux des RNM. Le niveau global de la migration interne est plus élevé en RMR
c' est-à-dire que les individus des RMR ont une propension à sortir plus forte que ceux des RNM. Une part importante de la migration en provenance d'une des RNM est destinée aux RMR. Dans la deuxième étape, nous avons analysé l'impact ultime des comportements démographiques observés sur l'évolution de la population. Les tendances actuelles
indiquent qu'aucune région n'est en mesure d'assumer elle-même le renouvellement de sa population, même en recourant à la migration interne. Mais il y a des disparités importantes : le taux net de reproduction multirégional est plus élevé dans les RNM que dans les RMR, et la capacité d'un nouveau-né de produire à son tour un enfant est plus
faible dans une RMR que dans une RNM. Dans un contexte de sous-fécondité, le rôle de l'immigration internationale devrait s'accroître: sans celle-ci, la population des régions, notamment des RMR, devrait décroître dans moins d'un quart de siècle. Toutefois, à long terme l'immigration
internationale sera incapable de freiner significativement le processus de vieillissement. de la population; elle ne pourra le ralentir que de façon modeste à Toronto, Montréal et Vancouver. La migration des individus implique non seulement une délocalisation des personnes, mais également un transfert d'années à vivre et d'enfants à naître. À cet égard, les grandes régions métropolitaines gagnent le plus puisque d'une part elles retiennent plus de 60% de leurs natifs jusqu'à l'âge productif et reproductif, et d'autre part elles " importent" plus de jeunes migrants, et donc plus d'années à vivre et d'enfants à naître. Enfin, il ressort clairement de nos recherches que lorsqu'on extrapole les comportements actuels jusqu'à obtenir l'état stable (c'est-à-dire celui de l'équilibre) Vancouver et
Toronto (donc !'Ontario et la Colombie-Britannique) accroissent leur importance alors que Montréal (donc le Québec) ainsi que les autres régions perdent du poids.