Η αλματώδης πρόοδος στις ασύρματες επικοινωνίες έχει φέρει ως αποτέλεσμα την δυνατότητα δημιουργίας μικρών σε μέγεθος μικροϋπολογιστικών συστημάτων που έχουν την δυνατότητα ασύρματης διασύνδεσης. Λόγω του μικρού μεγέθους αυτών είναι δυνατή η μεταφορά τους ακόμα και από φυσικά πρόσωπα και άρα προσφέρουν με τον τρόπο αυτό το πλεονέκτημα φορητότητας. Παράλληλα η επιθυμία για δημιουργία δικτύων μεγάλης κλίμακας με χρήση τέτοιων συσκευών χωρίς την δυνατότητα σταθερής παροχής ενέργειας δημιούργησε την ανάγκη μικρής εμβέλειας μετάδοσης και άρα πολλαπλών επαναμεταδόσεων ανά πακέτο δεδομένων μέχρι να φτάσει στον τελικό προορισμό του. Το ερευνητικό αντικείμενο αυτής της διδακτορικής διατριβής είναι η πρόταση μίας ολοκληρωμένης ασύρματης δομής που θα παρέχει δυνατότητες ασύρματης διασύνδεσης σε δίκτυα μεγάλης κλίμακας χωρίς ύπαρξη κεντρικής διαχείρισης. Το πρόβλημα της εύρεσης διαδρομών σε ένα ασύρματο δίκτυο κινούμενων αισθητήρων αποτελεί ένα πολύ δύσκολο εγχείρημα, ακόμα δε περισσότερο αν λάβουμε υπόψη μας και το ασύρματο μέσο που είναι ένα μη-ντετερμινιστικό φυσικό μέσο δικτύου. Η ύπαρξη απαιτήσεων πραγματικού χρόνου παρ’ όλες τις δυσκολίες υπάρχει σε εφαρμογές δικτύων κινούμενων αισθητήρων και δυσκολεύει περαιτέρω την σχεδίαση μιας δομής που θα διατηρεί διασυνδεσιμότητα μεταξύ των αισθητήρων του δικτύου ενώ παράλληλα θα ικανοποιεί τις απαιτήσεις πραγματικού χρόνου. Πρόσθετα οι δυναμικές συνθήκες που παρατηρούνται σε ένα ασύρματο δίκτυο κινούμενων αισθητήρων όσον αφορά σημαντικές παραμέτρους λειτουργίας όπως μεταβλητό φορτίο εφαρμογής, ταχύτητα φυσικής κίνησης του κινούμενου αισθητήρα και αριθμός συγκέντρωσης τους στην ίδια ασύρματη περιοχή καθώς και η μη ύπαρξη σταθερής παροχής ενέργειας, δημιουργούν την ανάγκη σχεδίασης μιας ασύρματης δομής που θα έχει την δυνατότητα να προσαρμόζεται στις εκάστοτε συνθήκες του δικτύου. Υποστηρίζοντας δυνατότητα προσαρμογής στις εκάστοτε συνθήκες του δικτύου ενώ παράλληλα εξυπηρετούνται οι απαιτήσεις πραγματικού χρόνου, δημιουργείται η δυνατότητα μείωσης του προσθετόμενου πρωτοκολλικού δικτυακού φόρτου άρα και μείωση της ενεργειακής κατανάλωσης του κινούμενου αισθητήρα. Προχωρώντας περαιτέρω, η λειτουργία του πρωτοκόλλου δρομολόγησης μπορεί επίσης να βελτιστοποιηθεί ώστε να εξυπηρετεί τα δρομολογούμενα πακέτα με μεγαλύτερη επιτυχία. Η παρούσα διδακτορική διατριβή έρχεται να καλύψει την ανάγκη για τεχνικές προσαρμοστικότητας σε ασύρματα δίκτυα στις εκάστοτε συνθήκες του δικτύου και να παρουσιάσει μια πρόταση πρότυπης υλοποίησης που να βελτιστοποιεί την λειτουργία του ασύρματου δικτύου, παρακολουθώντας σε πραγματικό χρόνο κρίσιμες μεταβλητές της λειτουργίας. Τα κυριότερα αποτελέσματα της παρούσας διδακτορικής διατριβής παρουσιάζονται παρακάτω: • Μελέτη και ανάλυση της εν γένη συμπεριφοράς υπαρχόντων προτεινόμενων δομών για την δρομολόγηση σε ασύρματα κινούμενα δίκτυα αισθητήρων. • Σχεδίαση και ανάλυση πρότυπης υβριδικής δομής στηριζόμενη σε γνωστούς αποδεκτούς αλγορίθμους δρομολόγησης. • Μελέτη και ανάλυση των μεταβλητών λειτουργίας και εξαγωγή των κρίσιμων μεταβλητών μέσω των οποίων μπορεί να γίνει η αναγνώριση κατάστασης του ασύρματου δικτύου. • Σχεδίαση, ανάλυση και υλοποίηση πρότυπου αλγορίθμου ελέγχου και προσαρμογής λειτουργίας της ασύρματης δομής στις εκάστοτε συνθήκες λειτουργίας του δικτύου. • Πλήρης υλοποίηση πρότυπης δικτυακής ασύρματης αρχιτεκτονικής με δυνατότητες αναπροσαρμογής σε μεταβλητές συνθήκες δικτύου. • Λήψη και δημοσίευση πλήρους συνόλου μετρήσεων μέσω προσομοίωσης της προτεινόμενης δομής με χρήση παγκοσμίου φήμης λογισμικού προσομοίωσης δικτύων και απόδειξη της επιτυγχανόμενης βελτίωσης λειτουργίας του δικτύου. / The progress in wireless telecommunications has resulted in the creation of small sized microprocessor systems that are wireless enabled. Due to the small size of these systems, they are considered portable since they can even be carried by a person. Furthermore, the need to create large scale wireless networks using such systems, without a fixed power supply, has created the constraint of small communication range for such devices. This leads to multiple retransmissions of data packets in order to reach their final destination within the wireless network. This communication is often referred to as multihop communication. The research objective of this thesis is to propose a new wireless architecture that will provide wireless connectivity for large scale wireless ad-hoc networks without the need of central management. The problem of finding a route, or even worse, the optimal route in a wireless ad-hoc network is very difficult and gets even worse if we consider the nature of the wireless medium that is un-deterministic and probably the less predictable medium used in networks. The need of real time constraints in wireless ad-hoc networks exists however, making even more difficult the design of a wireless architecture that will provide connectivity in the domain of a wireless network while managing to succeed in satisfying the real time constraints. Furthermore the dynamic nature of a wireless mobile network as far as important functional variables are concerned, like application load, speed of node movement, rate of connectivity in the same wireless domain, as well as the lack of a fixed power supply, create the need of adaptivity support, based on network status, in any wireless module designed to address the above problems. Supporting an adaptivity functionality based on the wireless network status, while managing to meet the real time constrains imposed from the application, we manage to lower the overhead of the network protocol, hence reducing the energy consumption of the wireless node. Moving forward, the functionality of the routing protocol itself is enhanced so as to route the data packets to the destination node with higher rates of success. This dissertation manages to fulfill the need for techniques of adaptivity in wireless ad-hoc networks by presenting a new wireless architecture, that is enhancing the general behavior of a wireless network by monitoring in real time various critical network variables and change the protocols behavior to adapt to changing network condition. The more important results of this dissertation are presented below: • Study and analysis of general behavior of already existing routing protocols for ad-hoc wireless networks. • Design and analysis of a prototype hybrid module, based on existing routing algorithms. • Study and analysis of functional variables, extraction of critical functional variables that can be used to identify the status of the wireless network within a certain domain. • Design, analysis and implementation of a prototype algorithm that controls and adapts the general functionality of the wireless module based on the network status. • Implementation prototype of a wireless architecture supporting automatic real time adaptability to network status based on real time monitoring of network variables. • Collection and publication of a full set of tests by using a world wide known software tool to simulate data networks, and proof of the resulted functionality enhancement of the wireless network’s behaviour.

Made available in DSpace on 2014-12-17T15:48:09Z (GMT). No. of bitstreams: 1 FernandoHLS_DISSERT.pdf: 2616798 bytes, checksum: 22d85c8d781aecef20ff0906635a692b (MD5) Previous issue date: 2013-08-05 / Coordena??o de Aperfei?oamento de Pessoal de N?vel Superior / One way to deal with the high complexity of current software systems is through selfadaptive systems. Self-adaptive system must be able to monitor themselves and their environment, analyzing the monitored data to determine the need for adaptation, decide how the adaptation will be performed, and finally, make the necessary adjustments. One way to perform the adaptation of a system is generating, at runtime, the process that will perform the adaptation. One advantage of this approach is the possibility to take into account features that can only be evaluated at runtime, such as the emergence of new components that allow new architectural arrangements which were not foreseen at design time. In this work we have as main objective the use of a framework for dynamic generation of processes to generate architectural adaptation plans on OSGi environment. Our main interest is evaluate how this framework for dynamic generation of processes behave in new environments / Uma forma de lidar com a elevada complexidade dos sistemas de software atuais ? atrav?s de sistemas autoadaptativos. Sistema autoadaptativos devem ser capazes de monitorar a si mesmos e ao seu ambiente, analisar os dados monitorados para determinar a necessidade de adapta??o, decidir como a adapta??o ser? realizada e, por fim, realizar as adapta??es necess?rias. Uma das maneiras de realizar a adapta??o de um sistema ? gerar, em tempo de execu??o, o processo que ir? executar a adapta??o. Uma vantagem dessa abordagem ? a possibilidade de levar em considera??o caracter?sticas que s? podem ser avaliadas em tempo de execu??o, como por exemplo, o surgimento de novos componentes que possibilitem novos arranjos arquiteturais que n?o foram previstos em tempo de projeto. Neste trabalho, temos como principal objetivo a utiliza??o de um framework de gera??o din?mica de processos para gerar planos de adapta??o arquiteturais sobre o ambiente OSGi. Nosso principal interesse consiste em verificar como esse framework de gera??o din?mica de processos se comporta em novos ambientes

Ces travaux de thèse s'inscrivent dans la thématique des objets connectés, désormais connue sous le nom de Internet of Things (IoT). Elle trouve son origine dans la démocratisation d'Internet depuis le début des années 2000 et la migration vers des appareils hautement mobiles, rendue possible grâce à la miniaturisation des systèmes embarqués. Dans ce contexte, l'efficacité énergétique est primordiale puisque les projections actuelles parlent de dizaines de milliards de composants connectés à l'horizon 2020. Or pour une question de facilité de déploiement et d'usage, une grande partie des échanges de données dans ces réseaux s'effectue via une liaison sans-fil dont l'implémentation représente une part importante de la consommation. Effectivement, la question de l'efficacité énergétique est en général considérée comme un problème de perfectionnement des architectures matérielles, souvent associé à une évolution favorable de la technologie. Toutefois, ce paradigme atteint rapidement ses limites puisqu'il implique nécessairement un dimensionnement fortement contraint pour être compatible avec les pires conditions d'utilisation, même si elles ne sont pas effectives la plupart du temps. C'est typiquement le cas avec les communications sans-fil puisque le canal radio est un milieu caractérisé par une forte variabilité en raison des phénomènes de propagation et de la présence d'interférences. Notre étude a donc porté sur la conception d'une chaîne de transmission dont le budget de liaison peut être dynamiquement modifié en fonction de l'atténuation réelle du signal, afin de réduire la consommation du système. La thèse a notamment contribué à la mise au point d'un récepteur auto-adaptatif spécifique à la norme IEEE 802.15.4, en proposant à la fois une architecture de modem numérique reconfigurable et à la fois une méthode de contrôle automatique du point de fonctionnement. Plus précisément, le travail s'est appuyé sur deux approches, l'échantillonnage compressif et l'échantillonnage partiel, pour réduire la taille des données à traiter, diminuant ainsi l'activité interne des opérateurs arithmétiques. En contrepartie, le processus de démodulation nécessite un SNR supérieur, dégradant la sensibilité du récepteur et donc le budget de liaison. Cette solution, portée sur une technologie STMicroelectronics CMOS 65 nm LP, offre une faible empreinte matérielle vis-à-vis d'une architecture classique avec seulement 23,4 kcellules. Grâce au modèle physique du circuit qui a été développé, la consommation pour la démodulation d'un paquet est estimée à 278 uW lorsque le modem est intégralement utilisé. Elle peut toutefois être abaissée progressivement jusqu'à 119 uW, correspondant à une baisse de la sensibilité de 10 dB. Ainsi, le modem implémenté et sa boucle de contrôle permettent d'économiser en moyenne 30 % d'énergie dans un cas d'utilisation typique. / This thesis work takes part in the connected objects theme, also known as the Internet of Things (IoT). It emerges from the Internet democratization since the early 2000's and the shift to highly mobile devices, made possible by the miniaturization of embedded systems. In this context, the energy efficiency is mandatory since today's projections are around tens of billions of connected devices in 2020. However for ease of deployment and usage, a large part of the data transfers in these networks is wireless, which implementation represents a significant part of the power consumption. Indeed, the energy efficiency question is addressed in general as a fine tuning of hardware architectures, which is often associated with a favorable technology evolution. Nevertheless, this design paradigm quickly reached its limits since it necessary implies a highly constrained sizing to be compatible with the worst operating conditions, even if they are not effective most of the time. It's typically the case with wireless communications since the radio channel is a medium characterized by a strong variability due to propagations effects and interferences. Thus, our study focused on the design of a communication chain whose link budget can be dynamically tuned depending on the actual signal attenuation, in order to reduce the system power consumption. The thesis has contributed to the design of a self-adaptive receiver dedicated to IEEE 802.15.4 standard, by proposing both a reconfigurable digital baseband architecture and an automatic control method of the operating mode. More precisely, the work relied on two approaches, the compressive sampling and the partial sampling, to reduce the data's size to process, decreasing the internal activity of arithmetics operators. In return, the demodulation processing needs a higher SNR, degrading in the same time the receiver sensitivity and thus the link budget. This solution, implemented in an STMicroelectronics CMOS 65 nm LP process, offers a low hardware overhead compared to conventional architecture with only 23,4 kgates. Thanks to the circuit physical model that has been developed, the power consumption for a packet demodulation is estimated to 278 uW when the baseband is fully activated. It can however be gradually decreased down to 119 uW, corresponding to a sensitivity reduction of 10 dB. Thus, the proposed digital baseband and its control loop save 30 % of energy in average in a typical use case.

Self-adaptive systems are capable of autonomously adjusting their behavior at runtime to accomplish particular adaptation goals. The most common way to realize self-adaption is using a feedback loop(s) which contains four actions: collect runtime data from the system and its environment, analyze the collected data, decide if an adaptation plan is required, and act according to the adaptation plan for achieving the adaptation goals. Existing approaches achieve the adaptation goals by using formal methods, and exhaustively verify all the available adaptation options, i.e., adaptation space. However, verifying the entire adaptation space is often not feasible since it requires time and resources. In this thesis, we present an approach which uses machine learning to reduce the adaptation space in self-adaptive systems. The approach integrates with the feedback loop and selects a subset of the adaptation options that are valid in the current situation. The approach is applied on the simulator of a self-adaptive Internet of Things application which is deployed in KU Leuven, Belgium. We compare our results with a formal model based self-adaptation approach called ActivFORMS. The results show that on average the adaptation space is reduced by 81.2% and the adaptation time by 85% compared to ActivFORMS while achieving the same quality guarantees.

Les décollements autour d’un corps en mouvement sont à l’origine de détériorations des performances aérodynamiques, de fatigues structurelles ou de nuisances sonores. La compréhension de ces phénomènes reste encore aujourd’hui l’un des enjeux majeurs de la recherche en aérodynamique. Le développement de systèmes permettant de contrôler l’écoulement et d’altérer ou de réduire les décollements apparaît comme une solution prometteuse en vue d’améliorer les performances aérodynamiques. On distingue les systèmes de contrôles passifs, simples d’utilisation mais incapables de s’adapter aux modifications de l’écoulement, des systèmes actifs qui disposent d’une grande adaptabilité mais nécessitent un apport extérieur d’énergie pour fonctionner. La stratégie du contrôle auto-adaptif s’apparente à un compromis entre ces deux méthodes. En s’inspirant de mécanismes présents dans la nature, elle permet d’associer amélioration des performances aérodynamiques, adaptabilité et autonomie. Ce travail de thèse porte sur l’étude expérimentale du contrôle du sillage turbulent d’un corps épais à l’aide d’actionneurs bio-inspirés avec un double objectif : i. déterminer les paramètres optimaux du dispositif de contrôle qui prend la forme d’un couple de volets flexibles, ii. Identifier les mécanismes physiques d’interactions entre l’actionnement et l’écoulement. Pour mener à bien cet objectif, de nombreux instruments de mesure complémentaires ont été mis en oeuvre. Une étude paramétrique a permis de démontrer l’efficacité du dispositif pour différentes configurations (fixes et auto-adaptatives) et d’identifier des configurations d’intérêt. La caractérisation de l’écoulement autour et dans le sillage du cylindre carré sans et avec contrôle a révélé un allongement de la longueur de recirculation à l’arrière du cylindre et la réduction de l’expansion du sillage. L’un des résultats majeurs de l’étude est que la réduction de traînée obtenue est principalement liée à une action du système sur l’anisotropie des fluctuations de l’écoulement et plus particulièrement sur l’entrainement du fluide dans le sillage de l’obstacle. / Flow separations around moving bodies lead to detrimental effects such as aerodynamic performances loss, structural fatigue and noises production. The understanding of these phenomena remains one of the most challenging issue of modern fluid dynamics. A promising solution to improve aerodynamic performances relies on the development of flow control devices able to prevent or mitigate the effects of separation. One can distinguish the passive flow control strategy, with easy to use devices but unable to adapt to the flow changes, from the active flow control strategy which benefits from a great adaptability but requires external power supply. Self-adaptive flow control appears to be a good compromise between those two strategies. Inspired from mechanisms at play in Nature, it combines good aerodynamic performances, self-adaptability and self-sustainability. This PhD thesis is dedicated to the experimental investigation of the turbulent flow over a bluff-body controlled by means of bio-inspired devices. The objective is two-folds : i. Design the control device which consists of a couple of compliant flaps, ii. Identify the physical mechanisms governing the interactions between the flow and the devices. A great number of complementary measurement techniques have been used in order to achieve these objectives. The efficiency of the devices for different configurations – locked and self-adaptive flaps - has been demonstrated through a parametric study. It has led to the identification of the main parameters involved in the control mechanism. The flow characterization around and in the wake of both uncontrolled and controlled cylinder revealed an increase in the length of the recirculation region and the reduction of the wake width. One of the major findings of this study is that the control essentially modifies the turbulent velocity field leading to a reduction of the lateral flow entrainment in the wake of the obstacle.

Made available in DSpace on 2014-12-17T14:56:05Z (GMT). No. of bitstreams: 1 GustavoFS.pdf: 1361196 bytes, checksum: fe1a67dcdb84a334e6c49247c8c68a06 (MD5) Previous issue date: 2005-01-21 / Image compress consists in represent by small amount of data, without loss a visual quality. Data compression is important when large images are used, for example satellite image. Full color digital images typically use 24 bits to specify the color of each pixel of the Images with 8 bits for each of the primary components, red, green and blue (RGB). Compress an image with three or more bands (multispectral) is fundamental to reduce the transmission time, process time and record time. Because many applications need images, that compression image data is important: medical image, satellite image, sensor etc. In this work a new compression color images method is proposed. This method is based in measure of information of each band. This technique is called by Self-Adaptive Compression (S.A.C.) and each band of image is compressed with a different threshold, for preserve information with better result. SAC do a large compression in large redundancy bands, that is, lower information and soft compression to bands with bigger amount of information. Two image transforms are used in this technique: Discrete Cosine Transform (DCT) and Principal Component Analysis (PCA). Primary step is convert data to new bands without relationship, with PCA. Later Apply DCT in each band. Data Loss is doing when a threshold discarding any coefficients. This threshold is calculated with two elements: PCA result and a parameter user. Parameters user define a compression tax. The system produce three different thresholds, one to each band of image, that is proportional of amount information. For image reconstruction is realized DCT and PCA inverse. SAC was compared with JPEG (Joint Photographic Experts Group) standard and YIQ compression and better results are obtain, in MSE (Mean Square Root). Tests shown that SAC has better quality in hard compressions. With two advantages: (a) like is adaptive is sensible to image type, that is, presents good results to divers images kinds (synthetic, landscapes, people etc., and, (b) it need only one parameters user, that is, just letter human intervention is required / Comprimir uma imagem consiste, basicamente, em represent?-la atrav?s de uma menor quantidade de dados, sem para tanto comprometer a qualidade da imagem. A grande import?ncia da compress?o de dados fica evidente quando se utiliza quantidade muito grande de informa??es e espa?os pequenos para armazenamento. Com esse objetivo ? que se apresenta esse trabalho no qual desenvolveu-se um m?todo para a compress?o de imagens coloridas e multiespectrais baseado na quantidade de informa??o contida em cada banda ou planos da imagem. Este m?todo foi chamado de Compress?o Auto-Adaptativa (C.A.A.), no qual cada banda da imagem ? comprimida com uma taxa de compress?o diferente, buscando um melhor resultado de forma a manter a maior parte da informa??o. A t?cnica baseia-se na compress?o com maior taxa para a banda com maior redund?ncia, ou seja, menor quantidade de informa??o e com taxas mais amenas ?s bandas com informa??o mais significativa. O CAA utiliza duas transformadas de imagens como elementos ativos da compress?o. A Transformada Cosseno Discreta (DCT) e a An?lise de Componentes Principais (PCA). A Imagem original (sem compress?o) ? processada pelo sistema CAA no espa?o RGB, sob o qual ? aplicado a transformada PCA, que leva a imagem para um novo espa?o (ou planos de dados), no qual as informa??es est?o descorrelacionadas. Neste espa?o gerado pela PCA, realiza-se a DCT em cada um dos planos individualmente, e, atrav?s de um limiar calculado em fun??o do resultado da PCA e de um par?metro de compress?o fornecido pelo usu?rio, ? que alguns elementos da matriz gerada pela DCT s?o descartados. Por fim realiza-se, respectivamente, a DCT e PCA inversas, reconstruindo assim uma aproxima??o da imagem. Quando comparada com a compress?o realizada pela tradicional JPEG (Joint Photographic Experts Group), a CAA apresenta, em m?dia, resultados cerca de 10 % melhores no que diz respeito a MSE (Mean Square Root), com duas grandes vantagens, por ser adaptativa, ? sens?vel ao tipo de imagem, ou seja, apresenta bons resultados em diversos tipos de imagens (sint?tica, paisagens, pessoas, e etc.), e, necessita apenas um par?metro de compress?o determinado pelo usu?rio

L’allégement des structures aéronautiques conduit à associer par stratification les composites aux métaux : on parle alors de multi-matériaux. L’assemblage mécanique des empilages nécessite au préalable des opérations de perçage qui s’effectuent majoritairement sur Unité de Perçage Automatique (UPA). L’objectif des travaux présentés dans ce mémoire est d’optimiser les opérationsde perçage effectuées sur UPA dans des multi-matériaux CFRP-7175-TA6V. Trois axes de recherche ont ainsi été étudiés. Le premier concerne l’optimisation de l’outil. L’utilisation d’une méthode de conception adaptée a conduit vers plusieurs pistes d’améliorations de la géométrie d’un foret. Le deuxième axe traite de la modélisation du perçage vibratoire. Cette méthode consiste à ajouter un mouvement de vibration axiale, au mouvement de coupe. Le dernier axe développe la technique du perçage auto-adaptatif. Une nouvelle méthode est proposée pour identifier les différents matériaux constituants l’empilage. / The weight reduction of aero structures has led to use composite materials combined to metallicparts to form multilayer materials. Stacked materials are drilled in one-shot during the assemblyprocess. The objective of this work is to find optimised parameters to drill efficiently CFRP-7175-TA6Vmaterial stack using Automatic Drilling Units (ADU). Three research areas have been explored. Thefirst one concerns drill bit optimisation. A customized functional analysis had led to several toolimprovements. The second area focuses on vibration-assisted drilling. This method consists in addinga reciprocating axial displacement. Formerly under ribbon form, the chips become well broken withthe vibrations and their evacuation gets better. At last, the self-adaptive drilling technique is studied.A new methodology for real-time material identification is proposed.

Warehouse trucks are now a practical equipment for lifting and moving goods in warehouses. The working situation for warehouse trucks is complicated. Spilling of machine oil or liquid product leads to low friction coefficient of the floor. Warehouse floors are normally made of concrete. Smooth concrete floors easily become slippery with liquid on the surface. With several tons of load on the fork, the braking distance is longer. An Anti-lock Braking System(ABS) for the truck control system is needed concerning the safety of the operator and people surrounding the truck. The warehouse truck braking is realized by controlling the motor torque. In order to control the torque, the truck wheel slip ratio is needed. With an accurate slip ratio, the control system will have accurate information regarding the vehicle status. To calculate the slip ratio, both the vehicle speed and wheel speed is needed. The wheel speed is derived from the motor speed. The vehicle speed is the challenge of this project. For normal passenger vehicles, sensors are installed on the trailer wheel where no slip occurs. In this case, the requirement is to use a lower number of sensors. There are two reasons of this requirement. It reduces the installation complexity and the cost of the control system. According to the literature study, a sensorless ABS system is impossible realize. Without sensor, it is not possible to estimate the vehicle status. One accelerometer is used in this project. An algorithm is designed and implemented in MATLAB. This algorithm solves the problem with zero-point drifting. Additional features are also added to the algorithm. The algorithm is a self-adaptive algorithm. It operates independently of the installation position of the accelerometer, without additional sensors. The result of the experiment with real measurements is very good. Future work on how to rewrite the algorithm from MATLAB programming to C programming is suggested in the end. Methods of implementation of the algorithm are also recommended. / Lagertruckar är en praktisk utrustning för att lyfta och flytta gods på ett lager. Arbetssituationen för en lagertruck är komplicerad. Oljespill eller spill av vätskor i allmänhet innebär att friktionskoefficienten för golvet blir låg. En förklaring till att golvet påverkas mycket av spill är att ytan är mycket slät eftersom den vanligvis är ett obehandlat betonggolv. Med flera ton last på gaffeln kan bromssträckan bli avsevärt längre om golvet är halt. För att uppnå tillräcklig säkerhet för föraren och personer i truckens omgivning skulle ett anti-låsningssystem (ABS) för bromsfunktionen vara nödvändig. Bromsfunktionen hos lagertrucken ombesörjs genom styrning av motormomentet. För detta ändamål är det nödvändigt att känna till drivhjulets âslipâ. Om denna storhet är känd med god noggrannhet kan styrsystemet få god information om fordonets status. För att kunna bestämma drivhjulets âslipâ krävs information om såväl fordonets hastighet som drivhjulets varvtal. Drivhjulets varvatl kan bestämmas mha motorvarvtalet. Fordonets hastighet är utmaningen i detta arbete. För normala passagerarfordon installeras varvtalsgivare på ett hjul som inte har drivning, eftersom detta inte har något âslipâ. I detta fall krävs emellertid att ett lägre antal sensorer ska användas. Det finns två skäl till detta krav. För det första minskas komplexiteten av installationen och för det andra minskas kostnaden. Enligt litteraturstudien är det omöjligt att realisera ett sensorlöst ABS-system. Utan givare kan fordonets status inte bestämmas. I detta projekt används därför en accelerometer. En algoritm har tagits fram och implementerats i MATLAB. Denna algoritm löser problemet med s.k. âzero-point driftningâ. Ytterligare funktioner har också lagts till i algoritmen. Algoritmen är själv-uppdaterande. Den fungerar oberoende av positionen av acelerometern utan ytterligare sensorer. Resultatet av mätningen en mycket bra. I framtiden kan MATLAB-koden ersättas med C-kod. Metoder för implementering av algoritmen föreslås också.

Future applications will run in a highly heterogeneous and dynamic execution environment that forces them to adapt their behavior and offered functionality depending on the user's or the system's current situation. Since application components in such heterogeneous multi-device systems will be distributed over multiple interconnected devices and cooperate to achieve a common goal, a coordinated adaptation is required to ensure a consistent system behavior. In this paper we present a decentralized adaptation middleware to adapt a distributed software system. Our approach supports the reliable execution of multiple adaptation operations that depend on each other and are performed transactionally even in unsteady environments coined by message loss or node failures. We implemented our approach in a search-and-rescue robot scenario to show its feasibility and conduct first performance evaluations.

The complexity of computer networks has been rising over the last decades. Increasing interconnectivity between multiple devices, growing complexity of performed tasks and a strong collaboration between nodes are drivers for this phenomenon. An example is represented by Internet-of-Things devices, whose relevance has been rising in recent years. The increasing number of devices requiring updates and supervision makes maintenance more difficult. Human interaction, in this case, is costly and requires a lot of time. To overcome this, self-adaptive software systems (SAS) can be used. SAS are a subset of autonomous systems which can monitor themselves and their environment to adapt to changes without human interaction. In the literature, different approaches for engineering SAS were proposed, including techniques for executing adaptations on multiple devices based on generated plans for reacting to changes. Among those solutions, also decentralised approaches can be found. To the best of our knowledge, no approach for engineering a SAS exists which tolerates errors during the execution of adaptation in a decentralised setting. While some approaches for role-based execution reset the application in case of a single failure during the adaptation process, others do not make assumptions about errors or do not consider an erroneous environment. In a real-world environment, errors will likely occur during run-time, and the adaptation process could be disturbed. This work aims to perform adaptations in a decentralised way on role-based systems with a relaxed consistency constraint, i.e., errors during the adaptation phase are tolerated. This increases the availability of nodes since no rollbacks are required in case of a failure. Moreover, a subset of applications, such as drone swarms, would benefit from an approach with a relaxed consistency model since parts of the system that adapted successfully can already operate in an adapted configuration instead of waiting for other peers to apply the changes in a later iteration. Moreover, if we eliminate the need for an atomic adaptation execution, asynchronous execution of adaptation would be possible. In that case, we can supervise the adaptation process for a long time and ensure that every peer takes the planned actions as soon as the internal task execution allows it. To allow for a relaxed consistent way of adaptation execution, we develop a decentralised adaptation execution protocol, which supports the notion of eventual consistency. As soon as devices reconnect after network congestion or restore their internal state after local failures, our protocol can coordinate the recovery process among multiple devices to attempt recovery of a globally consistent state after errors occur. By superseding the need for a central instance, every peer who received information about failing peers can start the recovery process. The developed approach can restore a consistent global configuration if almost all peers fail. Moreover, the approach supports asynchronous adaptations, i.e., the peers can execute planned adaptations as soon as they are ready, which increases overall availability in case of delayed adaptation of single nodes. The developed protocol is evaluated with the help of a proof-of-concept implementation. The approach was run in five different experiments with thousands of iterations to show the applicability and reliability of this novel approach. The time for execution of the protocol and the number of exchanged messages has been measured to compare the protocol for different error cases and system sizes, as well as to show the scalability of the approach. The developed solution has been compared to a blocking approach to show the feasibility compared to an atomic approach. The applicability in a real-world scenario has been described in an empirical study using an example of a fire-extinguishing drone swarm. The results show that an optimistic approach to adaptation is suitable and specific scenarios can benefit from the improved availability since no rollbacks are required. Systems can continue their work regardless of the failures of participating nodes in large-scale systems.:Abstract VI 1. Introduction 1 1.1. Motivational Use-Case 2 1.2. Problem Definition 3 1.3. Objectives 4 1.4. Research Questions 5 1.5. Contributions 5 1.6. Outline 6 2. Foundation 7 2.1. Role Concept 7 2.2. Self-Adaptive Software Systems 13 2.3. Terminology for Role-Based Self-Adaptation 15 2.4. Consistency Preservation and Consistency Models 17 2.5. Summary 20 3. Related Work 21 3.1. Role-Based Approaches 22 3.2. Actor Model of Computation and Akka 23 3.3. Adaptation Execution in Self-Adaptive Software Systems 24 3.4. Change Consistency in Distributed Systems 33 3.5. Comparison of the Evaluated Approaches 40 4. The Decentralised Consistency Compensation Protocol 43 4.1. System and Error Model 43 4.2. Requirements to the Concept 44 4.3. The Usage of Roles in Adaptations 45 4.4. Protocol Overview 47 4.5. Protocol Description 51 4.6. Protocol Corner- and Error Cases 64 4.7. Summary 66 5. Prototypical Implementation 67 5.1. Technology Overview 67 5.2. Reused Artifacts 68 5.3. Implementation Details 70 5.4. Setup of the Prototypical Implementation 76 5.5. Summary 77 6. Evaluation 79 6.1. Evaluation Methodology 79 6.2. Evaluation Setup 80 6.3. Experiment Overview 81 6.4. Default Case: Successful Adaptation 84 6.5. Compensation on Disconnection of Peers 85 6.6. Recovery from Failed Adaptation 88 6.7. Impact of Early Activation of Adaptations 91 6.8. Comparison with a Blocking Approach 92 6.9. Empirical Study: Fire Extinguishing Drones 95 6.10. Summary 97 7. Conclusion and Future Work 99 7.1. Recap of the Research Questions 99 7.2. Discussion 101 7.3. Future Work 101 A. Protocol Buffer Definition 103 Acronyms 108 Bibliography 109