Au cours des dernières décennies, le concept de « matériaux intelligents » a suscité un intérêt en croissance rapide en raison de l'apparition de plusieurs nouveaux types de matériaux polymères qui sont capables d'accomplir une fonction désirée en réponse à un stimulus spécifique de façon prédéterminée et contrôlée. Deux exemples représentatifs sont les polymères à mémoire de forme (SMPs) et les polymères autoréparables or réparables par un stimulus (SHPs). Ils sont sujets de cette thèse. D'une part, les SMPs sont des matériaux qui ont la capacité de mémoriser une forme spécifique. Après avoir été déformés et fixés à une forme temporaire, ils peuvent récupérer la forme originale et permanente sous l'effet d'un signal stimulant comme la chaleur, la lumière ou un champ électrique. Bénéficiant de la mise en œuvre relativement facile, les SMPs sont une alternative intéressante aux alliages à mémoire de forme bien établis; et ils ont trouvé un large éventail d'applications potentielles allant des implants pour la chirurgie non-invasive aux actionneurs sensibles aux environnements. D'autre part, les SHPs sont des matériaux qui sont capables de réparer des dommages mécaniques (fissures ou fractures) par eux-mêmes ou avec l'aide d’un stimulus externe. Leur développement a un grand intérêt pour améliorer la sécurité, prolonger la durée de vie et réduire le coût de l'entretien des matériaux. Sauf quelques matériaux souples (certains gels et élastomères) qui sont guérissables de façon vraiment autonome, la plupart des SHPs nécessitent l'intervention d'un stimulus comme c’est le cas pour les SMPs. L'objectif principal de cette thèse est de développer de nouveaux SMPs et SHPs contrôlables par un rayonnement lumineux. La stratégie que nous avons utilisée est basée sur l'ajout d'une petite quantité de nanoparticules d'or (AuNPs ) ou de nanotiges d'or (AuNRs) dans un SMP ou SHP pour absorber la lumière visible ou proche infrarouge. L’idée est d’utiliser la chaleur dégagée par les nanoparticules lors de l’absorption de la lumière due à la résonance plasmonique de surface (SPR) pour contrôler les transitions de phase dans les polymères et, par conséquent, de dicter leurs processus de mémoire de forme ou de guérison. Bien qu’un effet photothermique est à l'origine de ces processus, tous les avantages de l'utilisation de la lumière comme stimulus sont conservés, tels que l'activation à distance et le contrôle spatiotemporel. Plusieurs travaux de recherche ont été réalisés au cours de cette thèse, dont les résultats, nous l'espérons, peuvent constituer une contribution de base faisant l'utilisation d’AuNPs et AuNRs une technologie de plate-forme pour le développement des SMPs et SHPs contrôlables par la lumière. En ce qui concerne les SMPs, nous avons d’abord préparé un nouveau matériau nanocomposite AuNP-polymère à base d’oligo(ε-caprolactone) ramifié et réticulé. En faisant usage de chauffage localisé induit par la lumière, nous avons prouvé que la lumière visible peut être utilisée pour activer un processus de récupération de forme de manière sélective spatialement, et pour réaliser plusieurs formes intermédiaires sur-demande. En outre, nous avons constaté qu'en ajustant l'intensité de la lumière laser ou la quantité d’AuNPs, l'élévation locale de la température dans le matériau peut être importante et atteindre une amplitude prédéterminée sans influence défavorable sur ses environs. Cette caractéristique intéressante permet d'utiliser le même SMP pour des applications couvrant un large domaine de températures environnantes. De plus, dans cette étude, nous avons démontré comment l'énergie libérée dans un processus de récupération de forme contrôlé par la lumière peut être utilisée pour accomplir un travail mécanique. Sur la base du projet précédent, nous avons ensuite fait la première démonstration que la polarisation de la lumière peut également être utilisée pour contrôler l'effet de mémoire de forme ainsi que le processus de récupération de forme. À cette fin, nous avons conçu et préparé un SMP anisotrope contenant des AuNRs orientés par étirage de films de poly(alcool de vinyle) (PVA). L'idée est que la quantité de chaleur dégagée par les nanotiges d’or lors de l'exposition à la lumière proche infrarouge, est déterminée par l’absorption de photons qui, pour un matériau anisotrope, est dépendante de la polarisation de la lumière incidente. Nous avons montré qu’en effet, changeant la direction de polarisation du laser incident par rapport à la direction d'étirage du film tout en conservant toutes les autres conditions inchangées, permet de contrôler le degré d'élévation de température dans le matériau, ce qui détermine le processus de récupération de forme. En découvrant ce nouveau moyen de control, cette étude a élargi la boîte à outils pour les SMPs contrôlables par voie optique. Sur le côté SHPs, notre motivation d’exploiter l'approche photothermique est d'aborder la question difficile de la guérison de matériaux mécaniquement forts et dues. En général, une force mécanique élevée (ou une grande dureté) d'un matériau entrave sa capacité d’auto-guérison ou guérison induite par des stimuli en raison du manque de mobilité de chaînes du polymère, sachant que cette mobilité est cruciale pour la diffusion du polymère dans une région fracturée conduisant à la cicatrisation. Nous avons proposé la stratégie consistant à utiliser l'effet photothermique pour provoquer la transition de phase « fusion – cristallisation » pour la réparation. Dans une première étude, par le chargement d'une très petite quantité d’AuNPs dans deux polymères cristallins, le poly(oxyde d' éthylène ) (PEO, T[indice inférieur m~]63 °C) et le polyéthylène de basse densité (LDPE , T[indice inférieur m~]103 °C), nous avons réussi une guérison optique très rapide et efficace, fusionnant deux morceaux de polymère en contact en un seul avec des propriétés mécaniques bien récupérées. Nous avons confirmé le mécanisme de guérison basé sur la fusion des chaînes cristallisées lors de l’exposition à la lumière, suivie de la cristallisation lors du refroidissement après l'extinction du laser. Cette cristallisation des chaines ayant diffusé à travers les surfaces de coupe a pour effet de les fusionner pour la guérison. En plus de l'activation à distance et la capacité de cicatrisation rapide, nous avons aussi démontré le control spatial de la guérison optique car elle a lieu uniquement dans les régions fracturées exposées au laser. Après avoir appris comment utiliser l'effet photothermique découlant de la SPR d’AuNPs pour réaliser le control des processus de mémoire de forme et de guérison dans des polymères séparés, nous avons continué notre effort pour développer des matériaux qui possèdent les deux fonctions de mémoire de forme et de guérison commandées par la lumière. La réalisation d’un tel matériau est aussi une tâche difficile en raison de l'incompatibilité structurelle entre les SMPs et SHPs, puisque la structure de réseau réticulé nécessaire pour le mémoire de forme réduit généralement la mobilité de chaînes requise pour la guérison. Grâce aux connaissances générées par nos recherches, nous avons proposé un design de matériau consistant à réticuler chimiquement un polymère cristallin (PEO) chargé d’une petite quantité d’AuNPs. Notre étude a montré que ce matériau polymère acquise l’effet de mémoire de forme contrôlable par la lumière et la guérison optique rapide dus au même effet de chauffage localisé induit par un laser. En effet, l'effet photothermique peut activer le processus de récupération de la forme du matériau en élevant sa température au-dessus de la T[indice inférieur m] de la phase cristalline et, dans le même temps, permet la cicatrisation de fissures par l'intermédiaire de fusion des chaînes cristallisées sous exposition au laser et la cristallisation ultérieure lors du refroidissement après l’éteinte du laser. De plus, nous avons démontré que ces deux fonctions peuvent être exécutées de manière séquentielle sur le même matériau, sans interférence entre elles. La mise en œuvre simultanée des deux fonctions distinctes dans un seul matériau peut élargir les applications possibles de SMPs et SHPs. Par la suite, nous avons appliqué la stratégie établie avec des polymères cristallins aux hydrogels polymères. Il est connu depuis longtemps qu’il est très difficile d’obtenir des hydrogels mécaniquement robustes pouvant être réparés par effets de stimuli. Nous avons conçu et préparé un hydrogel hybride en chargeant une petite quantité d’AuNPs dans un hydrogel formé par copolymérisation du N, N-diméthylacrylamide (DMA), de l'acrylate de stéaryle (SA) et du N, N'- méthylène bisacrylamide (MBA). La force mécanique de cet hydrogel est donnée par une réticulation chimique qui coexiste avec une réticulation physique due aux chaînes latérales d’alkyles hydrophobes cristallisées. Encore une fois, par le contrôle de la transition de phase de « fusion-cristallisation » des chaînes SA à l'aide d'un laser, l'hydrogel hybride montre à la fois la fonction de mémoire de forme contrôlé par la lumière et la fonction de guérison optique efficace. Une grande contrainte à la rupture supérieure à 2 MPa a été obtenue pour un hydrogel coupé en deux et puis réparé par la lumièr. La dernière, mais non la moindre, contribution portée par l’étude dans cette thèse est une découverte que nous avons faite sur les SHPs. Nous avons observé que l’hydrogel de PVA physiquement réticulé, étant préparé par la méthode de congélation/décongélation, peut s’auto-guérir à la température ambiante sans l’utilisation d’un stimulus ou d'un agent de guérison. Cette découverte est importante étant donné que cet hydrogel est biocompatible et un matériau largement utilisé pour des applications. Notre étude a montré que la clé pour obtenir une guérison autonome efficace de l'hydrogel de PVA ayant une force mécanique relativement élevée est d'avoir une quantité suffisante de groupements hydroxyle libres sur les chaînes de PVA pour ponts-hydrogène et une bonne mobilité de chaîne assurant la diffusion du polymère à travers les surfaces de coupe.

The recent development of materials with autonomous repair capabilities has opened an exciting new field of polymer science expected to impact nearly every facet of modern society. Similar to natural systems, these "self-healing" materials sense when their structural integrity has been compromised (e.g., due to wear or damage) and respond with a viable repair mechanism. Despite the extraordinary number of successes and advances in this area, a means to ascertain instantaneous knowledge of a material's structural integrity, and more importantly, when it has been compromised, remains a considerable challenge in current systems and materials. To address this challenge, we report recent efforts toward the development of an electronically conductive material that is structurally dynamic and responds to various types of external stimuli. In particular, we have developed new synthetic methodology to prepare a variety of organometallic polymers containing a novel benzobisimidazolylidene or bis(benzoimidazolylidene) ligand, which is comprised of two linearly opposed N-heterocyclic carbenes (NHCs) annulated to a common linker, and various types of transition metals in the polymer's main-chain. Using this approach, polymers with molecular weights up to 10⁶ Da were prepared and cast into robust thin films. Using four-point probe technique, the inherent conductivities of these materials were found to be on the order of 10⁻³ S/cm. Secondly, the dynamics of these polymers were probed in solution using gel permeation chromatography. At specific cross-linker loadings, thermally-responsive gels were obtained. Collectively, these experiments suggested that the essential features for a thermally-responsive, structurally dynamic, conjugated organometallic polymer were developed. Efforts toward probing their ability to display self-healing characteristics in the solid-state are described. The inherent conductivity of the polymers permitted the healing behavior of thin films to be observed by scanning electron microscopy in the absence of a dopant. Long range goals of implementing and utilizing these materials in electronic circuits and other advanced devices are also described. An additional approach towards a dynamic material utilized functional imidazolium-based ionic liquids. A series of functional ionic liquids were produced by appending N-substituents containing pendant halides, alkynes, azides, furans and maleimides. These functional groups allowed for polymerization and crosslinking. The physical properties of the imidazolium monomers, as well as the resulting polymers, could be tuned by altering the anion. When a trifunctional monomer is used in conjunction with the polymerization of difunctional ionic liquids an insoluble crosslinked material forms. This behavior, combined with NHCs ability to bind transition metals as ligands and catalyze various organic transformations, provides potential for this system to be used as a method for catalyst recovery and ultimately catalyst recycling. / text

Un matériau qui se répare tout seul. Une fissure ou une rayure qui se rebouche elle-même après un impact, comme une blessure pour un être vivant. Le concept d’autoréparation ainsi décrit n’est plus une idée purement fantaisiste issue de l’imagination fertile des chercheurs. De récents travaux prouvent le contraire. Catalyse a choisi de mettre au point un processus d’autoréparation par l’intégration de microparticules contenant un principe actif liquide, libéré lors son l’éclatement. Ce liquide, un monomère, va alors polymériser, rebouchant ainsi la fissure et empêchant sa propagation.L’innovation de Catalyse a été d’imaginer une formulation autoréparante capable de polymériser directement au contact du milieu extérieur. Les éléments alors mis à disposition par l’environnement peuvent être la lumière (rayonnements UV ou visibles), l’oxygène, ou l’humidité. Les monomères envisagés pour l’encapsulation sont alors respectivement un acrylate, TMPTA, ou une époxy (mélangés avec un photoamorceur adapté), l’huile de lin (siccative) et un isocyanate trimère de l’hexamétylène diisocyanate. L’encapsulation des ces quatre composés est étudiée en parallèle et les travaux réalisés sont explicités dans les chapitres 2, 3 et 4 de ce document. Le TMPTA et l’huile de lin sont encapsulés par le procédé sol-gel, l’époxy et l’isocyanate, par polycondensation interfaciale. Les résultats obtenus sont variables d’un monomère à l’autre, mais dans l’ensemble, les résultats sont concluants et montrent d’une part, qu’il est possible d’obtenir des particules contenant un taux de principe actif intéressant et stables dans le temps, et d’autre part que suite à l’éclatement desdites capsules, le monomère polymérise, assurant ainsi le processus d’autoréparation. / A material that could repair itself, a crack that can heal itself after an impact, like a wound on the body. The concept of self-healing described is not science fiction created by the crazy imagination of researchers. Recent studies show otherwise. The French company CATALYSE has developed a process of self-healing through the integration of microparticles containing an active liquid ingredient that is released during a crack in the material. The liquid monomer fills the crack, polymerizes and prevents further spread. The innovation of CATALYSE was to imagine a self-repairing formula, which polymerizes when exposed to the outside of the self-contained environment. This includes light (UV or visible rays), oxygen or humidity. The corresponding monomers to be encapsulated are respectively an acrylate (for example TMPTA), an epoxy (mixed with an adapted photoinitiator), linseed oil or diisocyanate (for example an isocyanine trimer or hexamethylene diisocyanate). The encapsulations of these four compounds were studied in parallel and the results are explained in chapters 2, 3 and 4 of this document. The TMPTA and linseed oil are both encapsulated by the sol-gel process, the epoxy and isocyanate, by interfacial polycondensation. The results vary from one monomer to another but the overall results are conclusive. They show that it is possible to obtain a high percentage of the active ingredient and that the particles stay stable over time. Following the bursting of such capsules, the monomer polymerizes and ensures the self-healing process.

Cybercrime costs a total loss of about $338 billion annually which makes it one of the most profitable criminal activities in the world. Controlled malware (Botnet) is one of the most prominent tools used by cybercriminals to infect, compromise computer networks and steal important information. Infecting a computer is relatively easy nowadays with malware that propagates through social networking in addition to the traditional methods like SPAM messages and email attachments. In fact, more than 1/4 of all computers in the world are infected by malware which makes them viable for botnet use. This thesis proposes, implements and presents the Self-healing framework that takes inspiration from the human immune system. The designed self-healing framework utilises the key characteristics and attributes of the nature’s immune system to reverse botnet infections. It employs its main components to heal the infected nodes. If the healing process was not successful for any reason, it immediately removes the infected node from the Enterprise’s network to a quarantined network to avoid any further botnet propagation and alert the Administrators for human intervention. The designed self-healing framework was tested and validated using different experiments and the results show that it efficiently heals the infected workstations in an Enterprise network.

The annular cement sheath plays a crucial role in ensuring well integrity by providing adequate zonal isolation, stabilizing the formation, and protecting the casing from corrosion. A majority of well integrity problems originate from oil well cement shrinkage and shrinkage-induced cracking, as well as cracking induced by other external stresses. The addition of expansive additives is a commonly used way to compensate for shrinkage. Compared to conventional ettringite-based and CaO-based expansive additives, MgO has many advantages including a thermally stable hydration product, relatively low water requirements for hydration, and designable expansion properties. These make MgO a promising candidate for delivering the desired expansion under the complex and variable underground wellbore environment. Self-healing materials which have the capability for autonomous crack repair are an attractive solution for addressing cracking problems in oil well cement. Engineered additions of healing agents for autonomic self-healing via a delivery system have been reported as effective ways to promote self-healing in cementitious materials. Microcapsules that can be easily added to cement pastes and dispersed through the cement matrix are considered particularly suitable for use in oil well cement. This research project investigates the efficacy of reactive MgO expansive additives to reduce shrinkage, and of sodium silicate microcapsules to improve the self-healing properties of oil well cement, and explores the feasibility of their combined use in a high temperature oil well environment. Three types of reactive MgOs from different reactivity grades, high reactivity N50, medium reactivity MAG-R, and low reactivity 92/200, were characterised in terms of their expansion characteristics in cement paste prisms cured in water, and further tested on their autogenous shrinkage reduction at 80oC. The highly reactive N50 could only partially compensate for autogenous shrinkage, while the less reactive MAG-R and 92/200 completely compensated for autogenous shrinkage. MAG-R and 92/200 also showed effective drying shrinkage reduction at 90% RH. The restrained expansion of MAG-R and 92/200 during an early age was found to significantly improve the cracking resistance of oil well cement. The free expansion of 92/200, with low reactivity, caused significant strength reduction, but under restrained conditions the effect was mitigated as its compressive strength was enhanced by confined expansion. The addition of MAG-R increased compressive strength under both free and restrained conditions. Two groups of sodium silicate microcapsules, T1 with rigid polyurea shells and T2 with rubbery polyurea shells, were characterised in terms of their thermal stability, alkalinity resistance and survivability during cement mixing, and the results verified their suitability for use in oil well cement at the high temperature of 80 oC. The effects of the two types of microcapsules on the self-healing performance of oil well cement at 80 oC were monitored using a variety of techniques. Oil well cement itself showed very little healing capability when cured at 80 oC, but the addition of microcapsules significantly promoted its self-healing performance, showing reduced crack width and crack depth, enhanced tightness recovery against gas permeability and water sorptivity, as well as strength recovery. Microstructure analyses of the cracking surface further verified the successful release of the sodium silicate core and its reaction with the cement matrix to form C-S-H healing products. Both groups of microcapsules showed comparable self-healing efficiency. Their different shell properties mainly influenced the strength of oil well cement, with rigid shell microcapsules causing less strength reduction than rubbery shell microcapsules. The overall performance of oil well cement containing both reactive MgO and microcapsules were evaluated. The combined addition of MgO MAG-R and T1 microcapsules showed similar expansion performance and self-healing efficiency compared to their individual use. The use of MgO MAG-R compensated for the strength reduction caused by the addition of microcapsules, achieving an overall improvement in the cement strength.

Crack formation under tensile forces is a major weakness of concrete. Cracks make concrete vulnerable to the extreme environment due to the ingress of water and harmful compounds from the surrounding environment. Conventional methods of crack repairing are expensive and time consuming. It is estimated that in Europe, cost related to repair works is half of the annual construction budget and the US has average annual maintenance cost for existing bridges through the year is estimated to $5.2 billion. To overcome this problem, a self-healing concrete is produced based on the application of mineral producing alkaliphilic Bacillus Subtilis (strain 168) bacteria. Metabolic activities of these bacteria on calcium-based nutrients results in precipitation of calcium carbonate, which helps to repair concrete cracks. In bacteria based self-healing concrete, the bacteria are protected in the dense cementitious matrix by encapsulating them in “bacteria-carriers”. However, the presently available bacteria-carriers are not always suitable for concrete because of their complex manufacturing procedures or high cost. With the aim to develop a more suitable bacteria-carrier, in this study feasibility of cellulose fiber as a novel bacteria-carrier for self-healing mortar is investigated. Cellulose fibers compared to other bacteria-carriers can serve the dual purpose of arresting cracks and at the same time be a bacteria-carrier in large scale concrete construction. Two types of bacterial mortar by using cellulose fiber as a carrier was prepared. For one type, nutrients were added inside the mortar mix, while for the other, nutrients were added into the curing water. The two types of composites; control and cellulose fiber reinforced concrete (CeFRC) have also been investigated for autogenous healing of concrete. The crack healing efficiency of bacterial mortars was investigated using image analysis and ultrasonic pulse velocity (UPV) test and compared with unreinforced and control cellulose fiber mortars. Variation in compressive strength for all mixes compared to control mortar is also presented in this thesis. Research shows that self-sealing mortar using cellulose fiber as a bacteria-carrier result in maximum self-healing as compared to other mixes. This study also aims to evaluate the self-healing potential and water permeability of CeFRC. Compressive strength and flexural tests were also performed to evaluate the mechanical properties of the composites. Water permeability test was used to evaluate the coefficient of permeability and the self-healing performance was investigated by using UPV and a patented self-healing test. The results indicate that the water permeability coefficient decreased by 42% (+15% or -21%) whereas the healing ratio increased at a higher rate for the initial days of healing when cellulose fibers were added in the concrete. CeFRC also results in a 7.8% increase in flexural strength. / Graduate / 2020-09-13

The aim of this study was to develop a new single-part healing system for self-healing composites. The self-healing approach to composite repair has been developed in the last two decades and means that a damaged area can be repaired by material already housed within the structure. The background and development of self-healing has been reviewed. The two main self-healing mechanisms are discussed. To date only two part self healing systems have been examined. These require diffusion of the separate constituents to a single location in order to effect cure and restore strength. Single part adhesives do not have this disadvantage and are therefore very attractive. Several candidate single-part adhesive or resin systems were considered and discussed according to the critical requirements of a self-healing system. A series of experiments was undertaken to evaluate the possibility of candidate adhesive systems being effective for self-healing by focusing on the determination of storage stability and bonding efficiency. The results of storage stability testing showed that the stability of cyanoacrylate and polyurethane adhesives was poor. However silane and polystyrene cements showed good storage stability. Very low bonding efficiency was achieved with polystyrene cement but a 22% strength recovery was obtained with the silane 3-[tris(trimethylsiloxy)silyl]-propylamine. Suggestions for further research into single-part healing systems are also given.

This thesis is autobiographical in nature and follows my life experiences relating to the development and subsequent removal of a large epidermoid brain tumour. The resultant impairment of my faculties, and its effect on my vocational, emotional and spiritual life is outlined. My main means of expressing my journey from illness to partial recovery and self-renewal is through art-making. This art-making (a form of art self-therapy) is recorded in my paintings; included in my thesis as my main means of expression taking the place of the printed word, as my capacity to write and type is somewhat impaired. The main value of my thesis relates to recounting the experience, for others of the renewal of my life, following a major illness. Most brain tumours are fatal or severely limit the ability of a person to communicate, or limit their intellectual functioning. I was fortunate in that I could still communicate through using the visual arts; an area where I had retained my competencies. My thesis then, is aimed at increasing the understanding of illness, recovery and renewal for those in the helping and medical professions; also to give hope of life renewal through art expression and art therapy in cases where verbal and written means of communication are limited. The field of my thesis is adult education and personal learning through experience. This learning has focussed on using creative painting experiences as a way of self-healing. Those paintings that were significant in my recovery and renewal are exhibited in the Art Gallery section of this thesis. By viewing these artworks, you can share in, and understand my journey through illness, recovery and renewal through art-making, self-therapy.

The 3GPP Long Term Evolution (LTE) is considered as a dominant future cellular wireless technology in terms of performance and user experience. With technological advancement of the wireless networks, dependencies and business impact of the mobile network services have increased phenomenally. It is, therefore, crucial to address the issues regarding network infrastructure or service failure. In this thesis, a self-healing solution is presented for the LTE Evolved Packet Core (EPC) with a view to maintaining service continuity in the event of core network elements - the MME and S-GW failures. The core network element failures have significant impact on a larger number of subscribers in comparison to the access network element failures. In the proposed self-healing scheme, the restoration mechanisms and associate failover recovery procedures with regards to service survivability are described in details from the LTE network and protocol perspective. This thesis studies two different self-healing approaches - the centralized active-backup and distributed active-active and conducts simulation for each approach in various failure scenarios. The performances of each of these scenarios are evaluated in terms of service restoration time, throughput, EPS (Evolved Packet System) bearer delay etc. The results show that the proposed self-healing system can ensure service continuity at a certain level if resources are properly provisioned. And in terms of restoration delay, in general, the active-backup configuration performs better than the active-active configuration. The thesis presents analytical and simulation methods to estimate signaling message overhead at the LTE EPC that arises due to the recovery process. It also analyzes the bandwidth requirements of the signaling traffic that is incurred by the other operational procedures of the self-healing scheme and their ramification to the LTE core network. / UOIT

Fortums electric grid in Norra Djurgårdsstaden is a test grid for smart equipment and they are investigating new techniques and ways to improve the quality of the grid. With the quality improvements that are researched, a "self-restoring system" is a part of the research with the intention to lower the amount of outages and shorten the time it takes to restore faults. This thesis can be seen as a part of the optimization process of the grid in Norra Djurgårdsstaden where the benefits with a basic self-restoring system have been investigated on low voltage level. In the thesis the self-restoring system has been classified into a "basic" and an "advanced" category. The basic self-restoring system cross-connect several feeding paths by cross-connecting different low voltage grids and use mechanical equipment to change between cables when a fault in a cable occurs. The advanced self-restoring system uses several feeders and smart grid technology with equipment and softwares which communicate and visualize the grid. The difference between the systems is that the advanced system can visualize the grid and is able to tell when and where faults have occurred to a more detailed level. The advanced system can also calculate the power available and does not need the same amount of cables for redundancy because it can command users to lower their consumption when an outage has occurred. A decision was made to only investigate the technique on low voltage level because a basic system already exists on medium voltage in Norra Djurgårdsstaden. Results show that investing in a basic self-restoring system in Norra Djurgårdsstaden would cost about 2 million SEK and lower the total amount of outages for the customers in the area from 45 minutes per customer and year down to about 41 minutes. The reason why the decrease is only four minutes per year and customer is because faults occurring on higher voltage level cannot be reduced with the system. It is totally about 10 % of the faults that occur on low voltage level. One conclusion from the thesis is that the reduction in quality costs which are because to the lowered outages will not be enough to pay back the investment. More outage-time per customer and year need to be prevented with the system or the customers need to value reduced outages significantly more.