Experimentos têm revelado que redes de neurônios, tanto in vitro como in vivo, mantêm atividade descrita por avalanches e se organizam em um estado crítico no qual essas avalanches são distribuídas de acordo com leis de potência. Mostramos no presente trabalho que um modelo de rede de elementos excitáveis com sinapses dinâ- micas é capaz de exibir criticalidade auto-organizada para ampla região do espaço de parâmetros. Nossos resultados estão de acordo com outros estudos que indicam que a depressão sináptica de curto prazo constitui mecanismo suciente para produzir criticalidade em avalanches neuronais. No entanto, segundo diversos pesquisadores, embora o ajuste de parâmetros seja grosso para que haja criticalidade no modelo, é mais preciso dizer que o sistema não apresenta criticalidade auto-organizada genu ína, mas sim quasi-criticalidade auto-organizada, como os demais modelos não conservativos presentes na literatura. / Experiments have shown that neuronal networks, both in vitro and in vivo, maintain activity described by avalanches and they are organized into a critical state in which these avalanches are distributed according to power laws. We have demonstrated that a model based on a network of excitable elements with dynamical synapses is able to exhibit self-organized criticality for a wide range of the parameter\'s space. Our results are consistent with other studies that suggest short-term synaptic depression is enough to produce criticality in neuronal avalanches. However, according to several researchers, in spite of the tuning to be gross to ensure that there is criticality in the model, it is more accurate do not say that the system presents genuine self-organized criticality, but self-organized quasi-criticality as the other non-conservative models in the literature.

The central original contribution to knowledge proposed by this thesis is the setting forth of a conceptualisation of ethical theory specifically in relation to design, with a focus on visual communication design. Building on earlier work by design theorist Clive Dilnot in the area of design ethics and on philosopher Giorgio Agamben’s formulation of the philosophical concept of potentiality, a way of thinking about the relationship between design and ethics is proposed which concludes that design is in fact always inherently ethical. However, this conception of ethical design purposefully leaves questions of the qualification of good and bad unresolved, stating only that the ethical is the prerequisite condition in which both good and bad become possibilities. Design’s significantly unethical capability to suppress and anaesthetise individuals’ ethical experience is highlighted through a proposal of a process of an/aesth/ethics. Observation of the relationship between design and ethics in the real world through a series of interviews demonstrates something of the complexity of design’s relationship with ethics and the diverse range of positions, beliefs, attitudes and paradoxes abounding within the design profession when it comes to addressing the question of “good” design practice. Six “sites” of ethics within contemporary design discourse are introduced and discussed. The ethicality of design practices in relation to these sites are then analysed through the lens of the proposed ethical framework: identifying strengths, weaknesses and potentials within these observed strategies. The way of thinking about ethical design proposed here demonstrates potential in contributing to designers’ ability to critically consider the ethicality of their own practices. From this foundation they may be better equipped to begin addressing the question of the qualification of the “goodness” of design. In conclusion, proposals are made for how this framework could be practically developed and used to support and encourage ethical design in the real world.

Cette thèse propose des techniques de construction d'une séquence d'ordonnancement valide par un algorithme équitable pour des systèmes temps-réel multicoeurs subissant des pannes processeurs permanentes. Selon la nature des tâches les concepteurs peuvent allouer ou pas du temps supplémentaire pour récupérer l'exécution perdue. Dans un premier temps, nous traitons le cas de la défaillance d'un seul coeur. Nous montrons alors que s'il n'y a pas d'allocation de temps supplémentaire, prévoir un coeur de plus que le minimum nécessaire permet de construire une séquence valide : c'est la Technique de la Redondance Matérielle Limitée. Toutefois, si une telle allocation s'impose, nous proposons trois techniques : la Technique des Sous-tâches de Substitution qui augmente le WCET des tâches afin de prévoir du temps additionnel en remplacement du temps perdu, la Technique Contraindre puis Relâcher qui crée une marge de temps entre le délai critique et la période d'une tâche pour rattraper l'exécution perdue et la Technique du Flux Apériodique (TFA) qui réordonnance l'exécution perdue dans les unités de temps creux équitablement réparties. Ensuite, l'utilisation conjointe de ces techniques est envisagée en fonction de la nature des tâches impactées. Enfin, le cas de la défaillance de plusieurs coeurs est étudié. Pour ajuster la charge du système au nombre de coeurs fonctionnels, deux approches sont proposées : le changement de mode de criticité qui modifie les paramètres temporels de certaines tâches et l'abandon de certaines tâches en fonction de leur importance dans le système. / This thesis proposes several techniques to build a valid schedule with a Pfair algorithm for multicore real-time systems despite permanent processor failures. Depending on the nature of the tasks, additional time may be allocated or not to recover the lost execution. First, we consider a single core failure. We then show that if no additional time is allocated, the use of a single more core than the required minimum provides a valid schedule : it is the Limited Hardware Redundancy Technique. However, if full recovery is mandatory, we propose three techniques : the Substitute Subtasks Technique which increases the WCET to provide additionnal time which can be used to recover the lost time, the Constrain and Release Technique which creates a time margin between each task's deadline and the following period which can be used to recover the lost execution and the Aperiodic Flow Technique which reschedules the lost execution within the idle time units. Then, these techniques are mixed to adapt the scheduling behaviour to the nature of the impacted tasks. Finally, the case of the failure of several cores is studied.To adapt the system load to the number of remaining functionnal cores we use the criticality mode change which modifies the temporal parameters of some tasks or we discard some tasks according to their importance.

No description available.

Over the last decades sleep research has focused on epidemiological studies of how different factors affect sleep, and how sleep influences other physiologic and cognitive functions. However, the complex dynamics of sleep stage transitions and arousals which occur at time scales of seconds to minutes during healthy sleep and constitute the sleep micro-architecture are not yet understood. I analyze long-term continuous EEG recordings in rats and human, and dissect emergent signatures of criticality in the dynamics of cortical rhythm bursts in relation to their correlation properties and reciprocal coupling. I show that active states durations follow a power-law distribution while the quiet states durations follow an exponential-like behavior. Such emerging bursting activity in the brain rhythm dynamics described by power-laws and exhibiting long-range spatio-temporal correlations has been proposed as an indication of self-organized criticality (SOC). To have a deeper understanding of SOC in cortical rhythm bursting dynamics, it is essential to study the dynamical evolution of an entire network of physiologic interactions in the context of different physiologic states and pathologic conditions. The human organism comprises various physiological systems, each with its own structural organization and dynamic complexity, leading to transient, fluctuating and nonlinear signals. Understanding integrated physiologic function as emergent phenomena from complex interactions among diverse organ systems is the main focus of a new field, Network Physiology. I apply Network Physiology approach and the novel concept of time delay stability (TDS), and I demonstrate their utility to study transient synchronous bursts in systems dynamics as a fundamental form of physiologic network communications. My results demonstrate that during a given physiological state, the physiological network is characterized by a specific topology and coupling strength between systems. Probing physiological network connectivity and the stability of physiological coupling across physiological states provide new insights on integrated physiological function. / 2023-03-04T00:00:00Z

This project critically reflects on the relationship between human culture and the ocean from a posthumanist perspective. Specifically, it explores how ocean data can facilitate a relationship of care towards the sea. While doing this, this thesis explores how those critical ideas can be introduced when working in industry and natural science. In this project I propose and demonstrate a method of Relational Participatory Design as a possible way to not only create design outcomes with others but also establish relationships between different actors, human or nonhu-man involved in the process.

<p>Environmental concerns and the increase in energy demand with technology and innovations lead us to develop more efficient and environmentally friendly energy sources. With that purpose, Generation IV International Forum (GIF) Charter determined six advanced nuclear reactors. This thesis focuses on one of those reactors, Molten Salt Reactors (MSRs). MSR was chosen because of its outstanding feature; molten salt coolant/fuel. The fuel/coolant in this reactor type is in its molten salt form, which enables the reactor to reach a high temperature ( ̴ 600°C) with low pressure. As high temperature enhances thermal efficiency, low pressure makes the reactor safer. Besides, low pressure enables the reactor to be more economical because there is no need to use large pumps to maintain high pressure and no need for the pressure vessel, thereby decreasing the cost of construction and maintenance. Furthermore, molten salt reactors are inherently safer than light water reactors (LWRs) due to the molten salt fuel. Materials and structures are designed to tolerate the high-temperature molten salt, which means no risk of a core meltdown accident.</p> <p>A comprehensive literature review has been made on molten salt reactors to have a broad knowledge of MSR design characteristics and the current developments in the reactor. The literature review highlighted the notable features of this reactor design; being inherently safer and economical and having high thermal efficiency. In addition, the literature review showed that there are many studies on MSRs with different designs and materials for different purposes. However, the current parametric studies on literature were mainly performed for single channels and limited materials, meaning there is limited knowledge of whole reactor core analysis. This observation led us to perform a complete MSR core analysis with various design parameters; core size, moderator and fuel/coolant materials, and core configurations (hexagonal and hexahedral lattice geometries). Considering the advantages of MSRs and the need for detailed work on this reactor type in literature, a parametric study on the reactor was performed under the thesis presented here. </p> <p>Monte Carlo N-Particle (MCNP) 6.2 code is chosen for the criticality and the flux simulations. The single-fluid double-zone thorium-based molten salt reactor (SD-TMSR) has been selected as a base model. Single fluid means molten salt is the same as for fuel and coolant. Various molten salt compositions have been investigated to observe the effect of different elements and isotopes on criticality. The active core has two zones with the same molten salt but different fuel/coolant channel diameters for each zone. The inner zone represents where the fission reaction occurs mainly, and the outer zone serves as a blanket that enables the breeding process of thorium. To determine the criticality behavior of the reactor with moderation, simulations were performed with various inner zone fuel channel radii, from 0.25 cm to 5 cm. In comparison with the channel radius of the inner one, the outer zone fuel channel radius is fixed at 5 cm. </p> <p>Additionally, graphite and BeO moderators were examined separately to decide the material for better moderation. On the other hand, the core configuration is essential to make a more compact reactor. Therefore, hexagonal and hexahedral lattice geometries were simulated with all other cases; different fuel channel diameters, molten salts, and moderators. Before the flux distribution and the heat transfer calculations, the best combinations of the parameters which reach the criticality with the less fuel inventory have been decided and used for further calculations. Finally, four fuel/coolant salts have been chosen for the thermal neutron flux distribution simulations. Results for the flux distribution were represented with 2D and 3D color graphs, and results for different salts were compared with 2D graphs for axial and radial directions. Besides, to obtain a general idea of the reactor's power density and thermal-hydraulics characteristics, heat transfer calculations were done for the hot channel as a transition from neutronics to thermal hydraulics for future studies. With those calculations, power density, an average mass flow rate, and core inlet/outlet temperatures were determined.</p>

No description available.

Critical industrial applications in embedded field devices require reliability and consistency. Cloudbased services have been gaining attraction in embedded field devices for monitoring, optimization, predictive maintenance, and other supporting use cases. A significant challenge persists in enabling cloud-connection to the embedded field devices. The central issues on this matter are diversity, resource constraint, and the critical applications of these devices. This paper proposes a novel concept for enabling cloud connection to these devices. A dedicated software module, μConnector, has been introduced for cloud-related activities. It operates on Zephyr RTOS. The purpose of μConnector is to create a separation between critical and cloud related applications within the embedded field devices. μConnector is designed to be application-agnostic while being independent of vendor selection for hardware components. The scientific contribution of the paper lies in the introduction of μConnector. The presented concept addresses the challenges associated with cloud connectivity for embedded field devices. Its primary objective is to define architectural decisions guiding the implementation of the proposed software module.

No description available.