This study characterizes production-line defects in lithium-ion batteries' anode, cathode, and separators. Lithium-ion batteries demand has increased tremendously in the last decades due to their use in various applications, including electric vehicles, portable electronics, and energy storage systems. Therefore, characterizing defects in these batteries is crucial to understand their performance and reliability. This study uses scanning electron microscopy (SEM) and energy-dispersive X-ray spectroscopy (EDS) analysis to identify and analyze defects in the battery components. The major critical defects encountered in the study are impurities, contaminations, agglomerates, point defects, line defects, and more. This study helps improve the quality and reliability of lithium-ion batteries by providing guidelines to analyze and address essential deficiencies during the manufacturing process. / Denna studie karakteriserar produktionslinjedefekter i litiumjonbatteriers anod, katod och separatorer. Efterfrågan på litiumjonbatterier har ökat enormt under de senaste decennierna på grund av deras användning i olika applikationer, inklusive elfordon, bärbar elektronik och energilagringssystem. Därför är det avgörande att karakterisera defekter i dessa batterier för att förstå deras prestanda och tillförlitlighet. Denna studie använder svepelektronmikroskopi (SEM) och energidispersiv röntgenspektroskopi (EDS) analys för att identifiera och analysera defekter i batterikomponenterna. De största kritiska defekterna som påträffats i studien är föroreningar, föroreningar, agglomerat, punktdefekter, linjedefekter med mera. Denna studie hjälper till att förbättra kvaliteten och tillförlitligheten hos litiumjonbatterier genom att tillhandahålla riktlinjer för att analysera och åtgärda väsentliga brister under tillverkningsprocessen

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A possible mechanism to explain the origin of around 35 neutron–deficient stable isotopes with mass A≥75 between 74 Se and 196 Hg, known as the p–nuclei is the nucleosynthesis in the proton–rich neutrino–driven winds of core–collapse supernovae via the νp–process. However this production scenario is very sensitive to the underlying supernova dynamics and the nuclear physics input. As far as nuclear uncertainties are concerned, the breakout reaction from the pp-chains, 7Be(α, γ)11C, has been identified as an important link which can influence the nuclear flow and therefore the efficiency of the νp–process. However its reaction rate is not well known over the relevant energy range (T9 = 1.5–3). In this thesis we report on the direct first measurement of two resonances of the 7Be(α, γ)11 C reaction with previously unknown strengths using an intense radioactive 7Be beam from ISAC and the DRAGON recoil separator in inverse kinematics. Since resonance strength measurements with low mass beams using recoil separators depend strongly on the recoil angular distribution, which can exceed the acceptance of the separator, we first performed a proof–of–principle test by measuring a known resonance of the 6Li(α, γ)10B reaction, which also presents a similar challenge. Our results from the 6Li(α, γ)10B reaction are in agreement with literature, showing that DRAGON can measure resonance strengths of reactions for which the maximum momentum cone of the recoils exceeds its acceptance. From the newly measured 7Be(α, γ)11C resonance strengths we calculated the new reaction rate which is lower than the current recommended by 10–50% and constrained to 5–10% in the relevant temperature region. Using this new rate, we performed detailed nucleosynthesis calculations which suggest that there is no effect the production of light p–nuclei, but a production increase for CNO elements of up to an order of magnitude is observed. / Dissertation / Doctor of Philosophy (PhD)

Helicopter turboshaft engines may ingest large amounts of foreign particles (most commonly sand/dust), which can cause significant compressor blade damage and even engine failure. In many helicopters, this issue is mitigated by separating the particles from the intake airstream. An effective device for engine air-particle separation is the vortex tube separator (VTS), which uses centrifugal forces in a vortical flow to radially filter foreign particles from a duct with an annular exit. Dozens or hundreds of these devices are linked together on a shared manifold known as a VTS array. There is a distinct lack of scientific literature regarding these arrays, which likely feature significantly more complex flowfields than singular VTSs due to aerodynamic interactions between the devices. The research presented in this dissertation identifies and explains flow features unique to arrays by means of an experimental investigation downstream of various VTS configurations in a wind tunnel. Mean PIV flowfields reveal that the VTS array rapidly generates a strong central recirculation zone while a single VTS does not, implying the existence of axial flow gradients within associated separators that could affect filtration efficiency. The key factor here is the global swirl intensity, which is increased in array flows due to high angular momentum contributions from separators that are radially distant from the duct center. A preliminary momentum integral model is constructed to predict the onset of recirculation in VTS flows. Analysis is then extended to the unsteady flowfield, where it is shown that VTS-generated turbulence contains only low levels of anisotropy. Spectral proper orthogonal decomposition is conducted on the array flow; it reveals the existence of low-frequency harmonic behavior composed of back-and-forth pumping motions downstream of the central VTS. Additionally, a unique precession motion is found in the same region at a slightly higher frequency. Similar precessing vortex cores have been shown to reduce separation efficiency in other cyclone separators. Both of these coherent structures may be associated with the central recirculation zone and may interfere with VTS array filtration given their timescales relative to potential particle relaxation timescales. This dissertation opens the door for future experimental and computational studies of fluid and particle dynamics in VTS flows with the goal of improving VTS array-specific design philosophies. / Doctor of Philosophy / Vortex tube separators (VTSs) help protect helicopter engines by filtering harmful particles (sand, dust, snow, ash, sea spray, etc.) they would otherwise ingest. This is done by creating a vortex in which centrifugal forces eject particles outwards, separating them from the main airstream. These devices are effective when dozens are grouped together into VTS arrays, but little is understood of the complex air and particle dynamics that result from the many interacting vortices both in and around such arrays. This dissertation describes an early effort to study these aerodynamics and open the door for subsequent particle dynamics research. A laser-based measurement technique called particle image velocimetry is used to determine flow velocities downstream of a VTS array placed in a wind tunnel. When velocities are averaged together over time, they reveal a central recirculation zone (a known feature of intensely swirling flows) downstream of the VTS array that vanishes when only a single separator in the array is active. A mathematical model is developed to predict such recirculation. It demonstrates that a VTS array comprises many separators that are far from the center of the duct they are contained within, and these contribute greatly to the overall swirl intensity. Other data analysis techniques are used to investigate the instantaneous velocity flowfield, which differs significantly from averaged quantities. One such technique is spectral proper orthogonal decomposition, which extracts so-called "coherent structures" from the flow - correlated high-energy motions that exist at certain frequencies and may not be visible in the raw data. This analysis finds two interesting structures at the very center of the duct, possibly associated with the recirculation zone: a back-and-forth pumping motion at a very low frequency (and some of its harmonic frequencies), and a "precessing" (unsteadily rotating) vortex at a slightly higher frequency. These motions, as well as the central recirculation zone itself, are impactful because they may affect the filtration process within the VTS upstream of where they were measured. Such effects will be investigated in future experiments and, if confirmed, may influence the design of VTS arrays.

Dans cette thèse, nous étudions des problèmes de transversaux d'un point de vue tant algorithmique que combinatoire. Etant donné un hypergraphe, un transversal est un ensemble de sommets qui touche toutes les hyperarêtes. Un packing est un ensemble d'hyperarêtes deux à deux disjointes. Alors que la taille minimale d'un transversal est au moins égale à la taille maximale d'un packing on ne peut pas dans le cas général borner la taille minimale d'un transversal par une fonction du packing maximal. Dans un premier temps, un état de l'art rappelle les différentes conditions qui assurent l'existence de bornes supérieures sur la taille des transversaux, en particulier en fonction de la taille d'un packing. La plupart d'entre elles sont valables lorsque la VC-dimension de Vapnik-Chervonenkis de l'hypergraphe, est bornée. L'originalité de la thèse consiste à utiliser ces outils d'hypergraphes pour obtenir des résultats sur des problèmes de graphes. Nous prouvons notamment une conjecture de coloration de Scott dans le cas des graphes sans-triangle maximaux; ensuite, nous généralisons un résultat de Chepoi, Estellon et Vaxès traitant de domination à grande distance; enfin nous nous attaquons à une conjecture de Yannakakis sur la séparation des cliques et des stables d'un graphe.Dans un second temps, nous étudions les transversaux d'un point de vue algorithmique. On se concentre plus particulièrement sur les problèmes de séparation de graphe où on cherche des transversaux à un ensemble de chemin. En combinant des outils de connexité, les séparateurs importants et le théorème de Dilworth, nous obtenons un algorithme FPT pour le problème Multicut paramétré par la taille de la solution. / In this manuscript we study hitting sets both from a combinatorial and from an algorithmic point of view. A hitting set is a subset of vertices of a hypergraph which intersects all the hyperedges. A packing is a subset of pairwise disjoint hyperedges. In the general case, there is no function linking the minimum size of a hitting set and a maximum size of a packing.The first part of this thesis is devoted to present upper bounds on the size of hitting sets, in particular this upper bounds are expressed in the size of the maximum packing. Most of them are satisfied when the dimension of Vapnik-Chervonenkis of the hypergraph is bounded. The originality of this thesis consists in using these hypergraph tools in order to obtain several results on graph problems. First we prove that a conjecture of Scott holds for maximal triangle-free graphs. Then we generalize a result of Chepoi, Estellon and Vaxès on dominating sets at large distance. We finally study a conjecture of Yannakakis and prove that it holds for several graph subclasses using VC-dimension.The second part of this thesis explores algorithmic aspects of hitting sets. More precisely we focus on parameterized complexity of graph separation problems where we are looking for hitting sets of a set of paths. Combining connectivity tools, important separator technique and Dilworth's theorem, we design an FPT algorithm for the Multicut problem parameterized by the size of the solution.

This dissertation consists of two central parts. Part one of the dissertation examines the impact of interactive restructuring on decision processes and outcomes. Five experimental studies show that consumers examine less information and engage in more compensatory decision processes when interactive restructuring tools are available. Consumers also increase their use of restructuring tools in cognitively challenging choice environments. The availability of a sorting tool improves objective and subjective decision quality when attributes are positively correlated, or when the number of alternatives in a choice set is large, but not when attributes are negatively correlated or choice sets are small. Greater use of interactive restructuring tools has deleterious effects on decision quality when attributes are negatively correlated. Under time pressure the availability of an interactive restructuring tool improves decision quality, even when attributes are negatively correlated, since time pressure limits tool overuse. Finally, the effects of multiple interactive restructuring tools on decision making vary by the types of tools that marketers make available to consumers. Part two of the dissertation explores the effects of visual design on consumer preferences and choice. Experiment 1 demonstrates preference reversals when visual separators are between product alternatives versus between product attributes. Experiment 2 shows that when product attributes are negatively correlated, visually separating alternatives improves decision quality but visually separating attributes hurts decision quality. Visual separators do not affect decision quality when attributes are positively correlated. Experiment 3 extends experiment 2 to show that visual separators enhance decision-making efficiency and can limit the extent to which consumers adapt to contextual changes in choice environments. Finally, experiment 4 shows that, under time pressure, both visual separators between attributes as well as visual separators between alternatives improve decision quality when attributes are negatively correlated.

In this manuscript we study hitting sets both from a combinatorial and from an algorithmic point of view. A hitting set is a subset of vertices of a hypergraph which intersects all the hyperedges. A packing is a subset of pairwise disjoint hyperedges. In the general case, there is no function linking the minimum size of a hitting set and a maximum size of a packing.The first part of this thesis is devoted to present upper bounds on the size of hitting sets, in particular this upper bounds are expressed in the size of the maximum packing. Most of them are satisfied when the dimension of Vapnik-Chervonenkis of the hypergraph is bounded. The originality of this thesis consists in using these hypergraph tools in order to obtain several results on graph problems. First we prove that a conjecture of Scott holds for maximal triangle-free graphs. Then we generalize a result of Chepoi, Estellon and Vaxès on dominating sets at large distance. We finally study a conjecture of Yannakakis and prove that it holds for several graph subclasses using VC-dimension.The second part of this thesis explores algorithmic aspects of hitting sets. More precisely we focus on parameterized complexity of graph separation problems where we are looking for hitting sets of a set of paths. Combining connectivity tools, important separator technique and Dilworth's theorem, we design an FPT algorithm for the Multicut problem parameterized by the size of the solution.

Producing oil is a complex process where the fluids existing in a deep layer of the subsurface must be raised to the surface through the production well, where oil and natural gas are handled. The primary treatment of oil is basically done in two stages, the separation of gaseous and liquid phase separation, oil, water and other contaminants. Production facilities in offshore fields, which concentrates the largest and most recent discoveries of oil, the relatively small space in the production platforms has led to the employment of more compact process equipment. Pressure vessels are used in the separation of liquid phases, oil and water, imposing greater turbulence to fluids contributing to the formation and stabilization of emulsions of oil. This work aims at using CFD (Computational Fluid Dynamics) a software tool to visualize the behavior of fluid flow to analyze the dynamics of atmospheric flow in gravitational separators. To evaluate the influence of some internal atmospheric gravity separator tank known as Free Water Tank and how some its dimensions interfere with the gravitational separation. We restrict our analysis in a qualitative view of fluid dynamics in the gravitational separator and the occurrence of atmospheric phenomena that may influence its efficiency. For the separator model we could highlight the importance of the inductor tube, since the velocity profiles produced show the influence of its dimensions in the functionality of the equipment. Therefore the gravitational separators type, Free Water Tank height and diameter of the tube inducer, greatly influence the performance of the gravitational separator, thus, appears that supporting devices should be objects of analysis also at existing facilities. / Produzir petróleo é um processo complexo, no qual os fluidos existentes em uma camada profunda do subsolo devem ser elevados através do poço produtor, até a superfície, onde o petróleo e o gás natural são tratados. O tratamento primário do petróleo é realizado basicamente em dois estágios: a separação da fase gasosa e a separação da fase líquida constituída de petróleo, água e outros contaminantes. Nas unidades de produção em campos marítimos, onde se concentram as maiores e mais recentes descobertas de petróleo, o espaço físico relativamente pequeno nas plataformas de produção tem induzido ao emprego de equipamentos de processo mais compactos. Vasos de pressão são utilizados na separação das fases líquidas, nos quais ocorre grande movimentação dos fluidos, o que contribui fortemente para a formação e estabilização das emulsões de petróleo. Este trabalho objetiva com o uso de CFD (Computacional Fluid Dynamics) uma ferramenta computacional que permite visualizar o comportamento de fluidos em movimento apresentar uma análise da dinâmica de fluxo em separadores gravitacionais atmosféricos. Faz-se a avaliação da influência de alguns internos de um separador gravitacional atmosférico conhecido como Tanque de Água Livre (TAL), verificando-se como algumas dimensões dos mesmos interfere na separação gravitacional. Este trabalho restringiu-se a uma análise da dinâmica dos fluidos no separador gravitacional atmosférico e à ocorrência de fenômenos que possam influir na sua eficiência. Para o separador modelo pôde-se evidenciar a importância do tubo indutor, uma vez que os perfis de velocidade produzidos mostram a influência das dimensões deste dispositivo no desempenho do equipamento. Constatou-se que nos separadores do tipo Tanque de Água Livre a altura e o diâmetro do tubo indutor influenciam sensivelmente no desempenho do separador gravitacional, denotando a importância de analisar o efeito que estes dispositivos coadjuvantes podem ter nas instalações existentes para o tratamento primário de petróleo.

The present work draws together all current literature on particle separating devices and presents a review of the current research on rotor downwash-induced dust clouds. There are three types of particle separating device: vortex tube separators; inlet barrier filters; and inlet particle separators. Of the three, the latter has the longest development history; the former two are relatively new retrofit technologies. Consequently, the latter is well-represented in the literature, especially by computational fluid dynamics simulations, whereas the other two technologies, with specific application to rotorcraft, are found to be lacking in theoretical or numerical analyses. Due to their growing attendance on many rotorcraft currently in operation, they are selected for deeper investigation in the present work.The inlet barrier filter comprises a pleated filter element through which engine bound air flows, permitting the capture of particles. The filter is pleated to increase its surface area, which reduces the pressure loss and increases the mass retention capability. As particles are captured, the filter's particle removal rate increases at the expense of pressure loss. The act of pleating introduces a secondary source of pressure loss, which gives rise to an optimum pleat shape for minimum pressure drop. Another optimum shape exists for maximum mass retention. The two optimum points however are not aligned. In the design of inlet barrier filters both factors are important. The present work proposes a new method for designing and analysing barrier filters. It is found that increasing the filter area by 20% increases cycle life by 46%. The inherent inertial separation ability of side-facing intakes decreases as particles become finer; for the same fine sand, forward-facing intakes ingest 30% less particulate than side-facing intakes. Knowledge of ingestion rates affords the prediction of filter endurance. A filter for one helicopter is predicted to last 8.5 minutes in a cloud of 0.5 grams of dust per cubic metre, before the pressure loss reaches 3000 Pascals. This equates to 22 dust landings.An analytical model is adapted to determine the performance of vortex tube separators for rotorcraft engine protection. Vortex tubes spin particles to the periphery by a helical vane, whose pitch is found to be the main agent of efficacy. In order to remove particles a scavenge flow must be enacted, which draws a percentage of the inlet flow. This is also common to the inlet particle separator. Results generated from vortex tube theory, and data taken from literature on inlet particle separators permit a comparison of the three devices. The vortex tube separators are found to achieve the lowest pressure drop, while the barrier filters exhibit the highest particle removal rate. The inlet particle separator creates the lowest drag. The barrier filter and vortex tube separators are much superior to the inlet particle separator in improving the engine lifetime, based on erosion by uncaptured particles. The erosion rate predicted when vortex tube separators are used is two times that of a barrier filter, however the latter experiences a temporal (but recoverable post-cleaning) loss of approximately 1% power.

This diploma thesis is focused on the study of the preparation for fat separators and wastewater pipes that contains the microorganisms with lipolytic activity. Theoretical part of this thesis describes lipases, microorganisms producing this enzymes and usage of lipases. In this part possibilities of identification of microorganisms are presented too. The practical part is concerned with the study of commercial preparation Sany Duo Spezial with proven presence of microorganisms with lipolytic activity. These microorganisms were identified by means of the PCR method. This method identified mictoorganisms like genus Bacillus sp. Next characterization of the preparation was focused on the determination of COD and the investigation of the influence of various conditions of culture medium on the lipases production and their activity. The effect of temperature, ions and pH was studied. Lipolytic activity was determine spectrophotometricaly with usage of p-nitrophenyllaurate whitch dissociates to yellow product p-nitrophenol.