Orientador: Raimundo e Leite Cruz / Banca: João Carlos Cury Saad / Banca: Tarlei Arriel Botrel / Banca: Valdir Atsushi Yuki / Resumo: O presente trabalho teve como objetivo avaliar a variação da uniformidade de vazão, utilizando água com alto teor de ferro em microaspersores NaanDan autocompensantes, bocal marrom 35 L/h, foram testados no campo no Sítio Bocaina, localizado no município de Lençóis Paulista-SP, logo após 120 horas de uso foi retirado do campo e colocados em uma bancada no Laboratório de Irrigação e Drenagem da UNESP, em Botucatu -SP, onde foram submetidos a três sistemas (Tipo Malha, Tipo Linha Lateral e Tipo Serpentina) de irrigação, verificando inclusive sua pressão dos emissores. Através de coletas de água analisando sua qualidade e determinando os teores de ferro presentes que variaram de 1,6 á 2,6 mg/l, para testes na irrigação em microaspersores no campo. Os resultados mostraram que o ferro prejudica na vazão do microaspersor dependendo da pressão e do sistema utilizado, os sistemas tipo malha e linha lateral se mostram superiores aos do tipo serpentina. / Abstract: This study aimed to evaluate the variation of uniformity of flow, using water with high iron content in microsprinklers auto Naan Dan, brown nozzle 35 L / h, were tested in the field Bocaina Site, located in Lençois Paulista-SP , after 120 hours of use of the field was removed and placed on a bench in the Laboratory of Irrigation and Drainage of UNESP, Botucatu-SP, which were submitted to three systems (Mesh Type, Type and Type Lateral Line Serpentina) from irrigation, including checking of the pressure transmitters. By analyzing samples of water and its quality determines the levels of iron present ranging from 1.6 to 2.6 mg / l for tests on irrigation in microsprinklers field. The results showed that iron affect the flow of microsprinklers depending on the pressure and the system used, the systems mesh type and lateral line are shown above the type of coil. / Mestre

Les particules ultrafines (PUF) sont de nos jours susceptibles de se retrouver massivement dans l’air des lieux de travail et dans l’environnement, notamment de par leur génération non-intentionnelle par certains procédés industriels. Du fait de la toxicité de plus en plus avérée de ces particules, l’air contaminé doit être extrait des lieux de travail et filtré avant d’être rejeté dans l’atmosphère. Les filtres classiquement utilisés sont des filtres à fibres plissés présentant l’inconvénient vis-à-vis des PUF d’être rapidement et irréversiblement colmatés. Afin de trouver une alternative à ces filtres, il a été décidé d’étudier les lits granulaires. Pour ce faire, la cinétique de colmatage des lits granulaires par des PUF a dans un premier temps été étudiée à l’échelle macroscopique et microscopique par suivi des évolutions des performances ainsi qu’en procédant à des observations de structure de dépôt. Evaluer la capacité des lits granulaires à se positionner en tant qu’alternative aux médias fibreux peut nécessiter la connaissance des performances des lits granulaires dans un grand nombre de configurations. Pour s’affranchir des expériences correspondantes, un modèle théorique de prédictions des performances des lits granulaires en cours de colmatage a été développé. Ce modèle a par la suite permis par une optimisation multicritère de trouver la configuration optimale d’un lit granulaire amélioré. Enfin, des essais préliminaires très prometteurs d’une manche granulaire permettant d’augmenter la surface de filtration et l’efficacité de collecte ont posé les bases d’une potentielle utilisation des lits granulaires pour la filtration de PUF dans l’industrie / The air of workplaces and the environment can be contaminated by ultrafine particles (UFP) coming mainly from a non-intentional generation emitted by some industrial processes. The toxicity of these particles being more and more admitted nowadays, the polluted air of the workplaces has to be extracted and filtered in order to protect the workers and the public, respectively. The commonly used filters are pleated fiber filters which are rapidly and sometimes irreversibly clogged by the UFP. In order to find an alternative to these pleated filters, it was decided to study the granular beds. To do so, the clogging kinetic of granular bed by UFP was studied. This was achieved by conducting both macroscopic and microscopic studies of the granular bed clogging consisting in the monitoring of the evolution of the performances and in performing visualizations of UFP deposit structures. Evaluate the ability of granular beds to be an alternative to fiber filters can require the knowledge of the granular bed performances evolution for a large number of configurations. In order to avoid the realization of the corresponding experiments, a theoretical model was developed. Then, this model permitted by a multi-criteria optimization method to find the optimal configuration of an improved granular bed. Finally, some preliminary and very promising tests of a cylindrical granular bed filter permitting to increase the surface filtration and the collection efficiency laid the groundwork of a potential use of granular beds for the industrial UFP filtration

Submitted by (lucia.rodrigues@ufrpe.br) on 2016-10-13T15:06:26Z No. of bitstreams: 1 Sonivagno de Sousa Silva.pdf: 1092395 bytes, checksum: 8e337ebd4d4b11b5aae5edfb0bca1b16 (MD5) / Made available in DSpace on 2016-10-13T15:06:26Z (GMT). No. of bitstreams: 1 Sonivagno de Sousa Silva.pdf: 1092395 bytes, checksum: 8e337ebd4d4b11b5aae5edfb0bca1b16 (MD5) Previous issue date: 2011-07-29 / Coordenação de Aperfeiçoamento de Pessoal de Nível Superior - CAPES / Trickle irrigation is an irrigation technique which expands for the entire world. Use of microtubules as emitters in trickle irrigation has been used in small units of agricultural production due to its low cost and installation. This study evaluated hydraulic performance of four different microtubes (diameter of 0.6; 0.7; 0.8 and 1.0mm) under fertigation, simulating the growth of melon. Coefficient of manufacturing variation, coefficient of variation of discharge, coefficient distribution uniformity and clogging degree were used to determinate susceptibility to clogging. The experiment was conducted with three types of water, the first from a well in the Department of Rural Technology UFRPE, the second with fertilizers as recommended by EMBRAPA (2003), and the third also with fertigation, but according DANTAS (2010). Four lateral lines of the same diameter were installed in a bench trial, each line with 25 equal microtubes. Descriptive statistics was applied to obtain the mean, standard deviation and coefficient of variation. In conclusion, microtubules showed excellent coefficient of manufacturing variation. Distribution uniformity ranged from bad to good depending on the fertilizer and concentrations used. In general, larger diameter microtubes performed better than others. The use of fertilizers has influenced the hydraulic performance of irrigation system. / A irrigação localizada é a técnica que mais apresenta tendências de crescimento mundial. O uso de microtubos como emissores na irrigação localizada tem sido utilizado em pequenas unidades de produção agrícola devido a seu baixo custo de aquisição e instalação. Como forma de verificar a viabilidade técnica da utilização de microtubos o presente trabalho teve como objetivo avaliar o desempenho hidráulico de quatro microtubos gotejadores de diferentes diâmetros sob fertirrigação, simulando o cultivo do meloeiro com diferentes recomendações de adubação. Para tal, foi determinado o coeficiente de variação de fabricação (CVf), o coeficiente de variação de vazão (CVq), a uniformidade de distribuição (UD) e o grau de entupimento (GE). O experimento foi conduzido com três tipos de água, sendo o primeiro proveniente de um poço no Departamento de Tecnologia Rural da UFRPE (denominado como controle), a segunda sob fertirrigação conforme recomendação da EMBRAPA (2003), e a terceira também sob fertirrigação, sendo que de acordo com DANTAS (2010). Quatro linhas laterais de mesmo diâmetro foram instaladas em uma bancada de ensaio, sendo cada linha composta por 25 emissores iguais. Foi aplicada a estatística descritiva para a obtenção das médias, desvio padrão e coeficientes de variação. Com base nos resultados obtidos pode-se concluir que os microtubos analisados apresentaram CVf excelente e a uniformidade de distribuição variou de ruim a bom, dependendo dos fertilizantes e concentrações utilizadas. Em geral, os microtubos de maior diâmetro apresentaram melhor desempenho que os demais. O uso de fertilizantes comprometeu o desempenho hidráulico do sistema de irrigação.

Les générateurs de vapeur sont d'imposants échangeurs de chaleur qui alimentent les turbines des centrales nucléaires à eau pressurisée. Au cours de leur exploitation, des dépôts d'oxydes s'y accumulent et obstruent progressivement des trous prévus pour le passage du fluide. Ce phénomène, appelé colmatage, pose des problèmes de sûreté. Une méthode de diagnostic est nécessaire pour optimiser la stratégie de maintenance permettant de s'en prémunir. La piste explorée dans cette thèse est l'analyse de la réponse dynamique des générateurs de vapeur lors de transitoire de puissance, à l'aide d'un modèle physique monodimensionnel. Deux améliorations ont été apportées au modèle existant au cours de la thèse : la prise en compte des débits perpendiculaires à l'axe du générateur de vapeur et la modélisation du déséquilibre cinématique entre la phase liquide et la phase vapeur. Ces éléments ont ajouté des degrés de liberté permettant de mieux reproduire le comportement réel des générateurs de vapeur. Une nouvelle méthodologie de calage et de validation a alors été proposée afin de garantir la robustesse du modèle.Le problème inverse initial était mal posé car plusieurs configurations spatiales de colmatage peuvent donner des réponses identiques. La magnitude relative de l'effet des dépôts suivant leur localisation a été évaluée par analyse de sensibilité avec la méthode de Sobol'. La dimension de la sortie fonctionnelle du modèle a au préalable été réduite par une analyse en composantes principales.Enfin, une méthode de réduction de dimension appelée régression inverse par tranches a été mise en œuvre pour déterminer dessous-espaces de projection optimaux pour le diagnostic. Une méthode de diagnostic plus robuste et mieux maitrisée que celle existante a pu être proposée grâce à cette nouvelle formulation. / Steam generators are massive heat exchangers feeding the turbines of pressurised water nuclear power plants. Internal parts of steam generators foul up with iron oxides which gradually close some holes aimed for the passing of the fluid. This phenomenon called clogging causes safety issues and means to assess it are needed to optimise the maintenance strategy. The approach investigated in this thesis is the analysis of steam generators dynamic behaviour during power transients with a monodimensional physical model. Two improvements to the model have been implemented. One was taking into account flows orthogonal to the modelling axis, the other was introducing a slip between phases accounting for velocity difference between liquid water and steam. These two elements increased the model's degrees of freedom and improved the adequacy of the simulati onto plant data. A new calibration and validation methodology has been proposed to assess the robustness of the model. The initial inverse problem was ill posed: different clogging spatial configurations can produce identical responses. The relative importance of clogging, depending on its localisation, has been estimated by sensitivity analysis with the Sobol' method. The dimension of the model functional output had been previously reduced by principal components analysis. Finally, the input dimension has been reduced by a technique called sliced inverse regression. Based on this new framework, a new diagnosis methodology, more robust and better understood than the existing one, has been proposed.

The hyporheic interstitial was recognized as an integral zone within the aquatic ecosystem bearing important functions for both adjacent compartments, surface and ground water, about 50 years ago. Since then, rather disciplinary works gained knowledge on the organismic community of this ecotone, its spatial extent, the role of distinct parameters such as hydrology and morphology, temporal characteristics, process dynamics, the role for stream or groundwater quality and restoration measures. However, a systematic study on the risks to the hyporheic functions was missing to date. This thesis combined existing methods in order to gather an integrated set of information allowing for the assessment of the ecotonal status. This approach was applied to investigate the functional behavior towards stressors like increasing nutrient and fine sediment input into a rather pristine environment. An interdisciplinary risk assessment and the establishment of adapted measures was called for as land-use scenarios for the studied catchment area indicated progressive onland erosion. Therefore firstly, an integrated monitoring scheme was drawn up and conducted at three sites along a river that underlay a stressor gradient such as mentioned before. Secondly, the data sets were analysed in order to evaluate the status of the hyporheic funtions at the riffles. Thirdly, a coupled surface-subsurface modelling approach was set up to further study the impact of the stressors on the ecotonal integrity. And fourthly, an interdisciplinary consideration combined with studies on the catchments sediment budget and the rivers ecological status was applied to identify measures for the restoration and protection of the aquatic ecosystem. The analysis of the data gathered with the help of the established monitoring scheme revealed that elevated nutrient or fine sediment input lead to biological or physical clogging, respectively, with consequences for the hyporheic zone functions. The surface - ground water connectivity was either lowered in summer months, when biofilm growth was highest, or permanently, as fine sediment particles infiltrated into the interstices of the riverbed sediment. Scouring did not seem to take place as high amounts of fine particles were found in the matrix after discharge events of snowmelt and summer precipitation. With respect to the biogeochemical regulation function, biofilm material appeared to provide an autochthonous carbon source boosting microbial substance turnover. The sediment underneath the physical clogged layer was cut off from carbon and oxygen rich surface water and thus was not reactive. However, the enhanced surface area provided by the fine sediment within the topmost sediment layer seemed to support microbial processing. The inclusion of the results of a study concerning the ecological status at the investigated reaches lead to the deduction that biological clogging at the present degree was not affecting habitat quality. Whereas the physical clogging had tremendeous and lasting effects on the macroinvertebrate community which carries to the conclusion that sediment management within the studied catchment is of uttermost importance. A scenario analysis reflecting distinct clogging degrees and types with a calibrated model of a studied riffle within a pristine reach proved the observed loss of hydrologic connectivity due to physical and biological clogging. Further, a treshold of oxygen consumption rates above which the reproduction of salmonid fish would be unsuccessful was identified for the settings of the middle reaches. In summer month with low discharge it seemed to be likely that this treshold might be reached. Following, a dynamic discharge may be decisive to protect the ecotonal integrity. The integration with the outcome of an investigation regarding the sediment sources within the catchment allowed for two suggestions. On the one hand, river bank restoration and protection within the middle reaches need to be prioritised, and on the other hand, the conservation of the natural vegetation at the steep slopes within the mountaineous areas need to be undertaken in order to secure the pristine aquatic environment of this area. Hyporheic zone research of the last decade was driven by testing hypotheses on the functional significance of distinct spatial and temporal configurations in the field and by new modelling approaches. However, data on the quantification of the ecological impact of clogging processes were lacking. The thesis contributed to the systemic understanding of the hyporheic zone being affected by physical and biological clogging and new field data within a degrading pristine environment were generated, accessible for further hyporheic research. The interdisciplinarity enabled comprehensive statements for the usage of an Integrated Water Resources Management plan.

Porous asphalt has gradually gained a lot of popularity in the past ten years for its ability to reduce traffic noise, especially noise generated between tire and road surface. The acoustical absorption properties are mainly due to the pore structure and the texture of the mixture. However, the percentage of these pores decrease during the lifetime. The main reason is that dirt and organic material get stuck in the air void structure and eventually cause clogging. In Nordic countries, particles from the road which get released due to the use of spiked tires accelerate clogging. To minimize wear and tear of these roads, larger aggregates are used. But, larger stone size diminishes the noise absorption ability of the mixture. Another reason that is attributed to void reduction is post-compaction. The fact that these mixtures damage prematurely and need more maintenance than conventional pavements is the main reason for its limited use. Given these problem, it is therefore important to understand how clogging can be minimized and/or reverted via operational maintenance actions. Different types of cleaning vehicles have been used previously to restore porosity. Unfortunately, these cleaning attempts have led to ambiguities and the effect of cleaning is widely debated. A method to look inside and to measure this effect is needed. This thesis has compared nine field core samples of porous asphalt from E4 Huskvarna, with the aim to conduct an in depth analysis of the air voids distribution before and after cleaning with a particular cleaning method. For this, the Skanska maintenance vehicle was selected, named VägRen  which is claimed to be optimized for porous asphalt under Nordic conditions has been used to clean a 100 m section. Cores were drilled before and after cleaning. The samples were scanned with high resolution X-ray computed tomography (CT) scanner in order to capture the entire morphology.  The digital image analysis program, AvizoFire® was used to characterize the 3D internal structure of air voids. Porosity evaluation as a function of depth of the asphalt layers has been studied to analyze the void distribution and cleaning effectiveness of the dirt with the investigated method. The results show that: (i) No visible damage induced by VägRen could be detected. (ii) Skanska's maintenance vehicles increased the air voids in the entire cleaned core and connected air voids increased by 83 %. The knowledge generated from this study can assist in the broader understanding of effectively utilizing porous asphalt under Nordic Conditions, though more research will be needed for conclusive results on the general effectiveness of the cleaning method and the effect of the life time of the pavement. / Intresset för att använda bullerreducerande beläggningar har gradvis ökat de senaste tio åren på grund av dess förmåga att reducera trafikbuller och i synnerhet det buller som genereras mellan däck och vägbana. Den bullerreducerande förmågan beror främst på beläggningens textur samt porstruktur. Dessutom minskar den procentuella andelen hålrum med tiden, det är främst partiklar och vägdamm som fastnar i porstrukturen och medverkar till igensättning av hålrummen. Denna igensättning accelereras i de nordiska länderna på grund av frekvent användande av dubbdäck. För att minska dubbdäcksslitaget används ofta beläggningar med större maximal stenstorlek, dessa större stenar genererar dock mer trafikbuller. En annan faktor som kan bidra till minskat hålrum är relaterat till efterpackning av beläggningen. Faktum att dessa typer av asfalt försämras i förtid och kräver mer underhåll generellt motverkar en bredare användning av bullerreducerande beläggningar. Ovannämnda problem belyser vikten att förstå till vilken grad igensättningsprocessen av beläggningens porstruktur kan minimeras samt återställas med riktade underhållsåtgärder. För att förbättra den akustiska livslängden har olika typer av rengöringsutrustningar testats. Utvärderingen från dessa tester har inte varit entydiga, vilket har lett till att effekterna av rengöring har ifrågasatts. Det finns således ett behov av att kunna utvärdera porstrukturen före och efter rengöring. Föreliggande avhandling har jämfört nio borrkärnor från en bullerreducerande beläggning från E4 utanför Huskvarna, med syftet att utföra en djupanalys av borrkärnornas porstruktur. Skanskas egenutvecklade underhållsfordon, VägRen (VR), optimerad för nordiska förhållanden användes för att rengöra en sträcka på ca 100 m av E4:an. Borrkärnorna togs före och efter rengöringen. Provkropparna analyserades med en högupplöst röntgen datortomograf (CT) skanner för att framställa hela morfologin. Bilderna erhållna från datortomografin bearbetades till 3D med bildanalysprogrammet, AvizoFire®. Porositeten som funktion av beläggningsdjup har studerats för att analysera effeketen av den valda rengöringsmetoden. Resultaten visar  att: (i) Inga synliga skador på den rengjorda sträckan, orsakade av  VägRen. (ii) Skanskas rengöringsfordon återställde en del av hålrummet på samtliga nivåer för de tvättade provkropparna. Andel sammanhängande porer ökade med 83 \%. Kunskap erhållen från denna studie kan bidra till en djupare förståelse om mer optimal användande av bullerreducerande beläggningar under nordiskt klimat. Dock behövs det mer forskning för att fastställa effektiviteten av rengöringsmetoden och hur den påverkar livslängen.

Inclusions in molten steel have received worldwide concern due to their serious influence on both the steel product quality and the steel production process. These inclusions may come from the deoxidation process, reoxidation by air and/or slag due to an entrainment during steel transfer, and so on. They can break up a casting process by clogging a nozzle. A good knowledge on both steel flow and inclusion behavior is really important to understand nozzle clogging, as well as to take some possible measures to alleviate clogging. In this thesis, steel flow and inclusion behavior during a teeming process were investigated by mathematical simulations with verification by pilot-plant experiments. Firstly, steel flow phenomena during a ladle teeming process were studied. Different turbulence models, including the low Reynolds number k-ɛ model and the realizable k-ɛ model both with an enhanced wall treatment (EWT) and a standard wall function (SWF), were used to simulate this process. All of these turbulence model predictions generally agreed well with the experimental results. The velocity distributions in the nozzle were also predicted by these turbulence models. A large difference of the boundary-layer velocity predicted with these two near wall treatment methods was found. At the late stage of the teeming process, the drain sink flow phenomena were studied. The combination of an inclined ladle bottom and a gradually expanding nozzle was found to be an effective way to alleviate a drain sink flow during teeming. Then, inclusion behavior during a teeming stage was studied. A Lagranian method was used to track the inclusions in steel flow and compare the behaviors of different-size inclusions. In addition, a statistical analysis was conducted by the use of a stochastic turbulence model to investigate the behaviors of different-size inclusions in different nozzle regions. Inclusions with a diameter smaller than 20μm were found to have a similar trajectory and velocity distribution in the nozzle. However, inertia force and buoyancy force were found to play an important role for the behavior of large-size inclusions or clusters. The statistical analysis results indicate that the regions close to the connection between different angled nozzle parts seem to be very sensitive for an inclusion deposition. / <p>QC 20130305</p>

Managed Aquifer Recharge (MAR) can be conducted via wells or by spreading the water on a surface (e.g, during basin infiltration). While the former has the advantage of minimal area demand and the possibility of dual-use for groundwater abstraction, the latter usually has smaller construction costs and offers additional treatment to the water during infiltration via the vadose zone. Vadose Zone Wells (VZWs) combine many of these advantages, but as their hydraulics are more complex, infiltration rates and the degradation processes in the subsurface are more difficult to determine. Furthermore, they are prone to clogging and redevelopment has not been documented in the literature. Therefor, low-quality waters - with high content of suspended solids or dissolved contaminants/nutrients - are rarely infiltrated via VZWs. In this study, I will (1) evaluate the hydraulic advantage, VZWs can have over other vadose zone infiltration systems in a synthetical modeling study, (2) assess the spatial variability of key parameters for aerobic degradation below a VZW in a small-scale experiment, (3) determine the relationship between clogging dynamics and a well’s diameter and setup (gravel pack) in an experimental study and (4) demonstrate that the backflush of a VZW is possible - in contrast to the literature’s suggestions. All in all, VZWs appear to offer potential even for low-quality waters, and a further investigation for economical operation seems worthwhile. / Managed Aquifer Recharge' ('MAR' = 'Künstliche Grundwasseranreicherung') kann mit Brunnen oder über flächenhafte Versickerung erfolgen (z.B. durch Infiltrationsbecken). Während Brunnen wenig Platz benötigen und neben der Infiltration auch für die Grundwasserentnahme genutzt werden können, sind Becken meist günstiger in Errichtung und Erhaltung und die Versickerung durch die ungesättigte Zone kann die Wasserqualität erheblich verbessern. 'Vadose Zone Wells' ('VZWs' ≈ 'Ungesättigte Schluckbrunnen') verbinden einige dieser Vorteile, allerdings sind Infiltrations- und Abbauprozess aufgrund der ungleich komplizierteren Hydraulik schwer vorherzusagen. Darüber hinaus sind sie anfällig für Kolmation/Clogging und über ihre Regenerierung ist nach jetzigem Stande nichts bekannt. Im Allgemeinen werden deshalb Wässer mit niedriger Qualität - hohe Trübung und/oder Schad- und Nährstoffgehalte - selten durch VZWs versickert. In dieser Studie, werde ich (1) in einer synthetischen Modellstudie die hydraulichen Vorteile aufzeigen, die VZWs gegenüber anderen Versickerungsformen haben, (2) die räumlichen Unterschiede von Schlüsselparametern für den aeroben Abbau unter einem VZW in einem Laborexperiment untersuchen, (3) die Verbindung zwischen Kolmationsdynamik sowie Brunnendurchmesser und -aufbau (insb. der Kiesschüttung) herausarbeiten und (4) demonstrieren, dass eine Rückspülung von VZWs möglich ist - anders als es die Literatur nahelegt. Insgesamt, bieten VZWs ein hohes Potential - auch für Wasser niedriger Qualität, die allerdings noch durch weitere Untersuchungen bzgl. Kosten/Nutzen und Nachhaltigkeit bestätigt werden müssen.

Monitoring the non-metallic inclusions formed in steels is of the utmost importance. In fact, inclusions, depending on their type, can affect both the properties of the steel and its processing. Once the most problematic inclusions have been detected, solutions can be found and applied to counter the arising issues. One such solution is the addition of calcium during ladle treatment to modify the inclusions shapes and avoid the precipitation of problematic inclusions. The focus was put on the detection, analysis and calcium addition countermeasure of inclusions. No clear conclusion could be drawn as to the effects of calcium addition on the inclusions, due to the very high zirconium content of the inclusions. A high zirconium content has a significant impact on the thermodynamics governing inclusion formation and prevents reliable analysis of the results. After discussion with the company, it has been found that the zirconium is not present in the steel grade but instead originates from the samplers that were used. / Övervakning av icke-metalliska inneslutningar som bildas i stål är av yttersta vikt. Faktum är att inneslutningar, beroende på typ, kan påverka både stålets egenskaper och dess bearbetning. När de mest problematiska inneslutningarna har upptäckts kan lösningar hittas och tillämpas för att motverka de uppkomna problemen. En sådan lösning är att tillsätta kalcium under skänkbehandlingen för att ändra inneslutningarnas form och undvika utfällning av problematiska inneslutningar. Fokus låg på detektering, analys och kalciumtillsats som motåtgärd för inneslutningar. Ingen tydlig slutsats kunde dras om effekterna av kalciumtillsats på inneslutningarna, på grund av inneslutningarnas mycket höga zirkoniuminnehåll. En hög zirkoniumhalt har en betydande inverkan på den termodynamik som styr bildandet av inneslutningar och förhindrar en tillförlitlig analys av resultaten. Efter diskussion med företaget har det visat sig att zirkoniumet inte finns i stålsorten utan istället härrör från de provtagare som användes.

Elliptic curve cryptography (ECC) is extensively used in various multifactor authentication protocols. In this work, various recent ECC based authentication and key exchange protocols are subjected to threat modeling and static analysis to detect vulnerabilities, and to enhance them to be more secure against threats. This work demonstrates how currently used ECC based protocols are vulnerable to attacks. If protocols are vulnerable, damages could include critical data loss and elevated privacy concerns. The protocols considered in thiswork differ in their usage of security factors (e.g. passwords, pins, and biometrics), encryption and timestamps. The threatmodel considers various kinds of attacks including denial of service, man in the middle, weak authentication and SQL injection. Countermeasures to reduce or prevent such attacks are suggested. Beyond cryptanalysis of current schemes and proposal of new schemes, the proposed adversary model and criteria set forth provide a benchmark for the systematic evaluation of future two-factor authentication proposals.