This thesis reports on the application of ground penetrating radar (GPR) as a non-destructive technique for the monitoring of ring separation in brick masonry arch bridges. In addition, research is reported on the assessment of the clay capping layer often used in construction as a waterproof backing to arches. The thrust of the research is numerical modelling, verified by large laboratory experiments. Due to the heterogeneity of these structures, the resultant signals from the interaction between the GPR system and the bridge are often complex and hence, hard to interpret. This highlighted the need to create a GPR numerical model that would allow the study of the attributes of reflected signals from various targets within the structure of the bridge. The GPR numerical analysis was undertaken using the finite-difference time-domain (FDTD) method. Since micro regions in the bridge structure need to be modelled, the introduction of subgrids of supporting finer spatial resolution into the standard FDTD method was considered essential in order to economise on the required computational resources. In the main part of this thesis, it is demonstrated how realistic numerical modelling of GPR using the FDTD method could greatly benefit from the implementation of subgrids into the conventional FDTD mesh. This is particularly important when (a) parts of the computational domain need to be modelled in detail (i.e., ring separation between the mortar layers and the brick units, which is the case studied in this thesis); and also (b) when there are features or regions in the overall computational mesh with values of high relative permittivity supporting propagation of waves at very short wavelengths. A scheme is presented that simplifies the process of implementing these subgrids into the traditional FDTD method. This scheme is based on the combination of the standard FDTD method and the unconditionally stable alternating-direction implicit (ADI) FDTD technique. Given that ADI-FDTD is unconditionally stable, its time-step can be set to any value that facilitates the accurate calculation of the electromagnetic fields. By doing so, the two grids can efficiently communicate information across their boundary without requiring to use a time-interpolation scheme. The performance of ADI-FDTD subgrids when implemented into the traditional FDTD method is discussed herein. The developed algorithm can handle cases where the subgrid crosses dielectrically inhomogeneous and/or conductive media. In addition, results from the comparison between the proposed scheme and a commonly employed purely FDTD subgridding technique are presented. After determination of the optimum ADI-FDTD scheme, numerical experiments were conducted and calibrated using GPR laboratory experiments. Good correlations were obtained between the numerical experiments and the actual GPR experiments. It was shown both numerically and experimentally that significant mortar loss between the masonry arch rings can be detected. Dry hairline delaminations between the mortar and the brick masonry are difficult to detect using standard GPR procedures. However, hairline faults containing water produce distinct and detectable GPR responses. In addition, the clay layer was successfully identified and its thickness calculated to a satisfactory accuracy.

The GRP 5000 is a track measuring trolley capable of collecting track geometry data and performing clearance analyses based on laser scanning technology. The obtained laser data can also be used for as-built documentation, and the track recording functionality makes applications such as surveying, tamping assistance and slab track construction possible. The accuracy, huge data amount and time efficiency by which the system operates sets a new standard in railway surveying, and outdates traditional methods of manual and visual inspection. This thesis is a case study of the GRP 5000 with several objectives: a functional and technical description of the system is given; the accuracy of the system is evaluated, showing overall good values except for one of the sensors used; comparisons are made to other railway surveying techniques, such as track recording vehicles, manual devices and other track recording trolleys; possible improvements are pointed out, both based on comparison results as well as testing results. Finally, new and innovative ways of using the trolley, such as offtrack usage, as well as for the obtained laser data, such as GIS, maintenance aspects and CFD aspects, are examined.

No description available.

Punktförmige Verbindungen, wie das Clinchen, bieten vorteilhafte Eigenschaften und werden in zunehmendem Maße in der Dünnblech verarbeitenden Industrie für metallische Verbindungen eingesetzt. Sie spielen gegenwärtig für Metall-Kunststoff-Verbindungen eine untergeordnete beziehungsweise gar keine Rolle. Dies ist wahrscheinlich der Tatsache geschuldet, dass Kunststoffe aufgrund ihrer mechanischen Eigenschaften ungeeignet für das Clinchen scheinen. In der vorliegenden Dissertation werden die Grundlagen für das Clinchen von Metall-Kunststoff-Verbindungen erarbeitet und qualifiziert, so dass es möglich ist, damit eine Verbindung dieser Werkstoffe reproduzierbar herzustellen. Im Speziellen werden Prozessmerkmale und mechanische Verbindungseigenschaften des Clinchens von Metall-Kunststoff-Verbindungen sowie der Feuchtigkeitseinfluss des Kunststofffügepartners und der Einfluss von Wärme vor und/oder nach dem Fügen untersucht. / Because of its advantageous properties there is an extended utilization of point-shaped joints, like the clinching, in the sheet processing industry for metal-metal joints. These joining technologies are not relevant for metal-thermoplastic joints currently. The main reason for this could be the fact that the clinching process seems not to be eligible for thermoplastic materials. In the present thesis the fundamentals for clinching metal to thermoplastics were worked out and qualified. The results allow creating reproducible joints out of these materials. Process features and mechanical properties of clinched metal-thermoplastic joints were investigated. Also the influence of moisture and heat input during and after the clinching process was in focus.

Wind power is growing fast all over the world, and in Sweden alone thousands of turbines has been installed the last few decades. Although the number of decommissioned turbines so far is very low, the rapid installation rate indicates that a similar rapid decommissioning rate is to be expected shortly. If the waste material from these turbines is not handled sustainably the whole concept of wind power as a clean energy alternative is challenged. This study aims to present an accurate estimate of the amounts of waste material that will be generated from wind turbines in Sweden during the coming decades, allowing the waste management industry to plan for this and by extension prevent unnecessary energy losses through imperfect waste treatment. It should also present helpful information on how problematic waste can be reduced or avoided. VindStat’s annual report, presenting installation date and other relevant data for most installed turbines in Sweden, has been used as the base for the calculations. Information on material composition in different types and sizes of wind turbines has been extracted from various life cycle assessments, and by using the available parameters in the data base each turbine has been assigned a specific amount of steel, iron, copper, aluminum, blade material and electronics. An average life time of 20 years has been assumed, based on prior research and comparison with empiric data, and the material of each turbine is therefore seen as generated waste 20 years after installation date. To calculate the amount of waste material from replacing faulty components, empiric data over replacement rates in further developed markets has been combined with a prognosis over future development of installed wind capacity in Sweden based on a method described by prior research. As no sufficient way to predict how the future second hand market for turbines and components has been found, three different possible scenarios have been investigated to see how this may affect waste amounts. The results show that annual waste will grow slowly at about 12 % increase per year until around 2026, and then the average increase is 41 % per year until 2034. By then, annual waste amounts are estimated to have reached 237 600 tonne steel and iron (16 % of currently recycled amounts), 2 300 tonne aluminium (4 %), 3 300 tonne copper (5 %), 343 tonne electronics (<1 %) and 28 100 tonne blade material. There is no industrial scale recycling method for commonly used blade materials, and a high strength steel developed by Sandvik is proposed as a fully recyclable material to consider for further research. A well-functioning second hand market is shown to possibly have a major impact on waste amounts, at least in postponing it until better recycling systems are in place. / Vindkraft är en snabbt växande energikälla världen över och enbart i Sverige har tusentals vindkraftverk installerats under senaste decennier. Även om antalet nedmonterade verk än så länge är relativt lågt, indikerar det stora antalet årliga installationer att ett liknande antal nedmonteringar är att vänta inom kort. Om avfallsmaterialet från dessa verk inte hanteras på ett hållbart sätt riskeras att syftet med vindkraft som ett miljövänligt alternativ utmanas. Målet med studien är att presentera en noggrann uppskattning om vilka mängder avfallsmaterial som kommer att genereras från vindkraftverk i Sverige under kommande årtionden, vilken kan användas för att planera avfallshantering och på så vis i förlängningen undvika onödiga energiförluster genom felaktiga processer. Information om hur problematiskt avfall kan undvikas eller minskas ska även presenteras. Vindstats årliga rapport, vilken presenterar installationsdatum och annan relevant information för de flesta installerade vindkraftverk, har använts som bas för beräkningar. Information över materialfördelning i olika typer och storlekar av vindkraftverk har extraherats från ett antal livscykelanalyser och genom att använda tillgängliga parametrar i databasen har varje enskilt vindkraftverk tilldelats en specifik mängd stål, järn, koppar, aluminium, bladmaterial och elektronik. En genomsnittlig livslängd på 20 år har antagits, baserat på tidigare forskning och jämförelse med empirisk data, och materialet i vindkraftverken har därför setts som genererat avfall 20 år efter installationsdatum. För att beräkna mängden avfallsmaterial från utbytta komponenter har empirisk data över utbytningsfrekvenser hos mer utvecklade marknader applicerats på en prognos över över möjlig framtida utbyggnad av vindkraftskapacitet i Sverige som skapats enligt en metod beskriven i tidigare forskning. Eftersom ingen fullständig metod har funnits för att förutse hur framtida andrahandsmarknad för vindkraftverk och komponenter så har tre möjliga scenarion undersökts för att se hur detta kan komma att påverka avfallsmängder. Resultaten visar att de årliga avfallsmängderna förväntas växa med ca 12 % per år fram till 2026, och därefter i genomsnitt 41 % per år fram till 2034. Då förväntas avfallsmängderna uppnått 237 600 ton stål och järn (16 % av nuvarande återvunnen mängd), 2 300 ton aluminium (4 %), 3 300 ton koppar (5 %), 343 ton elektronik (<1 %) och 28 100 ton bladmaterial. Det finns ingen metod för att återvinna vanligen använda bladmaterial på industriell skala, och ett extra starkt stål utvecklat av Sandvik föreslås som fullt återvinningsbart alternativ att undersöka. En väl fungerande andrahandsmarknad visar sig kunna ha en betydande inverkan på framtida avfallsmängder, åtminstone genom att skjuta upp behovet av hantering tills ett mer effektivt system finns på plats.

Endogène du territoire et présente des enjeux politiques et économiques forts. Pour l’entreprise, il concerne la construction collective de ressources, spécifiques et localisées. A ce titre il présente également un enjeu managérial.La littérature a montré l’influence des préférences personnelles du dirigeant de PME sur certains choix managériaux, notamment concernant la localisation de l’entreprise. Prolongeant ces travaux, nous cherchons à comprendre l’influence que le lien personnel entre le dirigeant et le territoire exerce sur l’ancrage territorial des PME.Nous conduisons cinq études de cas, dans une perspective entrepreneuriale, en mobilisant à la fois la théorie des conventions et les travaux sur la proximité. A des fins instrumentales, nous utilisons le business model, dans une approche conventionnaliste (modèle Génération Rémunération Partage), afin de comprendre l’ancrage territorial des entreprises observées.Les résultats font apparaître l’influence effective du lien personnel du dirigeant au territoire. Ils montrent que l’ancrage opéré n’est pas nécessairement stratégique. Les liens peuvent être affectifs, opportunistes mais aussi idéologiques. Le dirigeant de PME apparaît comme un acteur politique du territoire. La recherche montre également la diversité des situations d’ancrage (ancrage sociétal, de patrimoine, d’innovation). Enfin, elle permet d’approfondir l’articulation entre différentes formes proximiques et conventionnelles dans la coordination en situation d’ancrage.Mots / Territorial anchoring is an interdisciplinary subject. It contributes to the endogenous development of the territory and raises strong political and economic issues. For the company, it involves a collective construction of resources that are specific and localized. As such, it is also a managerial challenge.The literature has shown the influence of the personal preferences of the SME's manager on some business choices, particularly those concerning the location of the company. In line with these studies, the aim of our study was to understand the influence of the personal link between the entrepreneur and the territory upon the territorial anchoring of SMEs.We conducted five case studies in an entrepreneurial perspective, mobilizing both the conventions theory and research on proximity. The business model was used as an analytical framework to understand the territorial anchoring of the SMEs observed. The GRS model (Generation Remuneration Sharing) is a conventionalist modelisation of the business model.The findings highlight the effective influence of the link between the entrepreneur and the territory. Territorial anchoring is not always the result of a strategic decision. Links can be emotional, opportunistic, but also ideological. The SME manager appears as a political actor in the territory. The study also showed the diversity of anchoring situations. Anchoring can be established on CSR - Corporate Social Responsibility -, local heritage, and innovation. Finally, it deepens our understanding of how coordination in an anchoring situation is based on combinations of proximities and conventions

No description available.

Non-destructive testing (NDT) of glass-fibre reinforced polyester (GRP) composite materials has been becoming increasingly important due to their wide applications in engineering components and structures. Electronic Speckle Pattern Interferometry (ESPI) has promising potential in this context because it is a non-contact, whole-field and real-time measurement system. This potential has never been fully exploited and there is only limited knowledge and understanding available in this area. This reality constrains the wide popularity and acceptance of ESPI as a novel NDT technique. Therefore it is of considerable importance to develop an understanding of the capability of ESPI with respect to damage evaluation in GRP composite materials. The research described in this thesis is concerned with an investigation into the applicability of ESPI in the NDT of GRP composite materials. Firstly, a study was carried out to determine excitation techniques in terms of practicality and effectiveness in the ESPI system. Three categories of defects were artificially introduced in GRP composite materials, namely holes, cracks and delaminations each with different geometrical features. ESPI was then employed to evaluate the three kinds of defects individually. It has been found that cracks and holes on back surfaces can be defined when the technique is used in conjunction with thermal excitation. Internal Temperature Differential (ITD) induced fringe patterns were more efficient than External Thermal Source (ETS) induced fringe patterns with regard to detecting the presence of holes and cracks. In the case of delamination, ESPI was found to be capable of detecting the damage when used in combination with mechanical excitation originating from a force transducer hammer. The geometrical features and magnitudes of delaminations were also established as being quantifiable. The validation of ESPI as an NDT technique was carried out in an attempt to establish a better understanding of its suitability and have more confidence in its applications. Four damaged specimens were Subjected to ESPI examination in conjunction with visual inspection, ultrasonic C-scan and sectioning techniques. The geometrical features and magnitudes of damage evaluated using ESPI showed a good correlation with those evaluated by conventional techniques. Poor visibility and readability is an inherent problem associated with ESP! due to an overlapping between the noise and signal frequencies. An improvement of image quality is expected in an attempt to achieve a wide acceptance of ESPI as a novel NDT technique. It has also been demonstrated that this problem can be tackled using optical phase stepping techniques in which optical phase data can be extracted from the intensity fringes. A three-frame optical phase stepping technique was employed to produce the "wrapped" and "unwrapped" phase maps which are capable of indicating internal damage with high visibility and clarity. Finally ESPI was practically employed to evaluate damage in GRP composites introduced by quasi-static and dynamic mechanical loading. It was found that ESP! was capable of monitoring the progressive damage development of specimens subjected to incremental flexural loading. The initial elastic response, damage initiation, propagation and ultimate failure of specimens were clearly characterised by the abnormal fringe pattern variations. In a similar manner, ESPI was employed to evaluate the low velocity falling weight impact induced damage. A correlation was established between the magnitude of damage and the impact event parameters as well as the residual flexural properties.

Ce manuscrit est dédié à l'approximation numérique de plusieurs modèles du transfert radiatif. Dans un premier temps, l'attention est portée sur le modèle cinétique d'ordonnées discrètes. Dans le but de coupler ce modèle avec d'autres phénomènes plus lents, il est nécessaire d'avoir des méthodes numériques performantes et précises sur des temps longs. À partir d'une double approximation polynomiale de la solution en temps et en espace, on développe un schéma de type GRP d'ordre élevé sans restriction sur le pas de temps pour un système hyperbolique linéaire sur des maillages non structurés. Ce schéma est ensuite étendu pour le modèle d'ordonnées discrètes. Dans un second temps, on s'intéresse à des modèles aux moments issus du transfert radiatif. En effet, dans certaines applications, les modèles aux moments de type M1 conservent de nombreuses propriétés de l'ETR et fournissent une approximation suffisante de la solution. Après avoir résolu le problème de Riemann associé au modèle M1 gris, on considère l'approximation numérique du modèle M1 multigroupe. Une attention particulière est portée sur le calcul des moyennes d'opacités et des lois de fermeture. Un algorithme de précalculs est alors mis en place. La dernière application traitée dans ce mémoire porte sur une extension du transfert radiatif pour estimer des doses de radiothérapie. À la différence du M1 gris usuel, les flux dépendent ici de fonctions peu régulières en espace. Grâce à des changements de variables, un schéma HLL rétrograde est développé. De nombreux exemples numériques illustrent l'intérêt des schémas obtenus dans cette étude.

The multi-net Global Routing Problem (GRP) in VLSI physical design is a problem of routing a set of nets subject to limited resources and delay constraints. Various state-of-the-art routers are available but their main focus is to optimize the wire length and minimize the over ow. However optimizing wire length do not necessarily meet timing constraints at the sink nodes. Also, in modern nano-meter scale VLSI process the consideration of process variations is a necessity for ensuring reasonable yield at the fab. In this work, we try to nd a fundamental strategy to address the timing-driven Steiner tree construction (i.e., the routing) problem subject to congestion constraints and process variation. For congestion mitigation, a gradient based concurrent approach (over all nets) of Erzin et. al., rather than the traditional (sequential) rip-and-reroute is adopted in or- der to propagate the timing/delay-driven property of the Steiner tree candidates. The existing sequential rip-up and reroute methods meet the over ow constraint locally but cannot propagate the timing constraint which is non-local in nature. We build on this approach to accommodate the variation-aware statistical delay/timing requirements. To further reduce the congestion, the cost function of the tree generation method is updated by adding history based congestion penalty to the base cost (delay). Iterative use of the timing-driven Steiner tree construction method and history based tree construction procedure generate a diverse pool of candidate Steiner trees for each net. The gradient algorithm picks one tree for each net from the pool of trees such that congestion is e ciently controlled. As the technology scales down, process variation makes process dependent param- eters like resistance, capacitance etc non-deterministic. As a result, Statistical Static Timing Analysis or SSTA has replaced the traditional static timing in nano-meter scale VLSI processes. However, this poses a challenge regarding the max/min-plus algebra of Dijkstra like approximation algorithm that builds the Steiner trees. A new approach based on distance between distributions for nding maximum/minimum at the nodes is presented in this thesis. Under this metric, the approximation algorithm for variation aware timing driven congestion constrained routing is shown to be provably tight and one order of magnitude faster than existing approaches (which are not tight) such as the MVERT. The results (mean value) of our variation aware router are quite close to the mean of the several thousand Monte Carlo simulations of the deterministic router, i.e the results converge in mean. Therefore, instead of running so many deterministic Monte Carlo simulations, we can generate an average design with a probability distribution reasonably close to that of the actual behaviour of the design by running the proposed statistical router only once and at a small fraction of the computational e ort involved in physical design in the nano regime VLSI. The above approximation algorithm is extended to local routing, especially non- Manhattan lambda routing which is increasingly being allowed by the recent VLSI tech- nology nodes. Here also, we can meet delay driven constraints better and keep related wire lengths reasonable.