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1
Mann, Jason Peter. "Serpentine Activation for CO2 Sequestration." Thesis, The University of Sydney, 2014. http://hdl.handle.net/2123/12054.
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Serpentinite calcination currently represents a key step for its activation within ex situ aqueous mineral carbonation. However, the dehydroxylation kinetics that govern this process remain largely unresolved within literature. Available Arrhenius parameters (i.e. A and E) span a wide range of values and appear correlated in terms of a kinetic compensation effect (i.e. linear relationship between loge(A) and E). Following this observation, a revised model for dehydroxylation is presented, validated against a systematic investigation into the role of particle size on the dehydroxylation rate for both South West Oregon and New England Australia Serpentinite using non-isothermal TGA. Within these experiments, dehydroxylation occurs primarily through a particle size dependent mechanism, best described by the canonical spherical, retreating interface model (R3), with statistically equivalent Arrhenius parameters reported between specimens. Examining the processing side of activation, this thesis additionally explores the role of flash calcination, where dehydroxylation is achieved in extremely short residence times (<2 s) through the use of high temperatures (>1073 K) and rapid heating rates (>104 K/s). High temperatures required by this technique however, led to instant deactivation of the calcine through recrystallisation of the dehydroxylated phase to the high temperature product, forsterite. Investigation into this phase transition indicates magnesium leachability declines proportionally to the extent of forsterite content. Kinetic parameters for this transition are reported, allowing quantification of this deactivation process as a function of calcination temperature, time, and particle size. Closing this thesis, the dissolution of activated serpentinite within the CO2-H2O system is examined at conditions relevant to ex situ mineral carbonation (10 MPa, 423 K), with emphasis on reaction pressure, temperature, and particle size on the magnesium leaching rate.
2
Merkulova, Margarita. "Comportement du fer et d'autres ions échangeurs d'électrons en contexte de subduction." Thesis, Université Grenoble Alpes (ComUE), 2016. http://www.theses.fr/2016GREAU030/document.
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Les zones de subduction sont les plus grands systèmes de recyclage de notre planète. Elles permettent le recyclage de l'eau contenue dans la croûte océanique hydratée et de la lithosphère du manteau supérieur. L'eau joue un rôle clé dans de nombreux processus associés aux zones de subduction, comme la tectonique des plaques, la production de magma, le transport élémentaire et la génération de tremblement de terre. La composition chimique, le contenu H2O de la lithosphère océanique, l'âge et la géométrie de la plaque océanique sont les principaux facteurs contrôlant les processus de subduction, y compris la déshydratation.L'objectif principal de cette thèse est d'étudier le régime de la libération de l'eau depuis la plaque océanique subductante et le comportement du Fe et du S en contenus dans les serpentinites, qui représentent la principale lithologie de roche hydratées océaniques. L'approche expérimentale de ce travail permet d’étudier les changements chimiques et minéralogiques associés lors la déshydratation des serpentinites de différentes compositions. Un certain nombre de techniques d'analyse ont été utilisées pour étudier l’influence de la composition de la roche totale sur la composition des assemblages produits. Les intervalles de pression de température expérimentalement étudiés, à savoir 2 GPa et 450-900C, représentent des zones de subduction chaudes. L'extrapolation à d'autres gradients géothermiques communs a été faite par thermodynamique. Les compositions de serpentinite étudiées correspondent aux péridotites serpentinisées naturelles décrites pour la lithosphère océanique.Mon travail indique que la teneur en Fer contrôle a stabilité thermique d’antigorite. Déshydratation de serpentinites avec Fe, par conséquent, pasee à des températures plus basses par rapport aux assemblages Fe-libres. La déshydratation observée dans les systèmes sans Fer se fait le long d'une réaction univariante, alors que dans les systèmes contenant du Fer, la déshydratation se fait sur un domaine de température (réactions de déshydratation divariantes). De plus, la présence de Al dans serpentinite stabilise clinochlore, qui conserve 15% de l'eau initiale jusqu'à ~ 120 km (820°C/2 GPa) dans subduction chaud. Cette dépendance sur Fe et Al apporte importance de considérer non seulement la géométrie et l'âge de la plaque océanique, mais aussi une composition de lithologies lors de la modélisation et d’interprétation de subduction. Une comparaison entre la profondeur des séismes et la profondeur de déshydratation des serpentinites indique une possible contribution de la libération de l'eau à la sismicité dans les zones de subduction chaudes et à pente faible.La spectroscopie d'absorption des rayons X montre une réduction progressive de Fe et de S dans des serpentinites. Le rapport Fe3+/ Fetotal, de la roche totale, élevé dans la serpentinite, diminue dans les assemblages anhydres de haute température par décomposition de la magnétite (< 550°C) et de l’antigorite (700°C). La pyrite des serpentinites se transforme en pyrrhotite en-dessous de 450°C et induit une libération de ¼ de soufre initial, probablement sous forme de H2S. La magnétite et la pyrite présentes dans des serpentinites, sont des phases cruciales pour la production de fluides très oxydés et d’espèces volatiles soufrées qui peuvent être transportés depuis la plaque subductée vers le coin mantellique. Application des résultats montre que les fluides s’élevant de la plaque océanique sont responsables de l'oxydation du manteau; et décomposition de la magnétite et l’antigorite avec au moins 100°C différence peut provoquer une libération de fluides chimiquement différents à peu profond (basse-T) et profondes (T-élevé) parties de subductionSubduction zones are the largest recycling systems of our planet. Subduction zones involve recycling of water from hydrated oceanic crust and lithosphere to the upper mantle. Water plays a key role in subduction zone processes, including plate tectonics, magma generation, elemental transport and earthquake generation. The chemical composition, H2O content of oceanic lithosphere sinking to the mantle, age and geometry of subducting oceanic slab are the main factors controlling subduction zone processes including dehydration.The principle aim of this dissertation is to investigate the regime of water release from subducting oceanic plate and the associated behavior of Fe and S in serpentinites, which are the main carriers of water into the slab. The experimental approach of my work allows one to compare chemical and mineral changes occurred during dehydration of serpentinites with different composition. A number of analytical techniques were applied to study the influence of bulk rock composition on the mineral chemistry of produced assemblages. The experimentally investigated pressure-temperature ranges, i.e. 2 GPa and 450-900C, are representative for hot subduction zones. The extrapolation to other common geothermal gradients was done through thermodynamic modeling. The investigated serpentinite compositions correspond to natural serpentinized peridotites described for oceanic lithosphere.Bulk Fe content was demonstrated to decrease thermal stability of antigorite by 25C on average. Dehydration of Fe-bearing serpentinites, consequently, occurs at lower temperatures compared to Fe-free assemblages. Dehydration reactions observed in Fe-free systems are univariant reactions, while in Fe-bearing systems, serpentinites dehydration appears over a range of temperature through divariant reactions. Moreover, the presence of Al in serpentinite stabilized clinochlore, which retains 15% water initial contain in serpentinite down to ~120km (820°C/2 GPa) within hot subduction. Such a dependence of serpentinite dehydration on bulk Fe and Al brings importance of considering not only geometry and the age of the slab, but also a composition of slab lithologies while modeling and interpreting processes in subduction zone. A comparison of the depths of serpentinite dehydration and seismicity revealed a strong correlation and therefore a potential contribution of water release to seismicity in the case of hot subduction zones (i.e., Chili type subduction).X-ray absorption spectroscopy measurements revealed a progressive reduction of Fe and S in investigated serpentinites. The bulk Fe3+/Fetotal ratio initially high in serpentinite is shown to decrease in anhydrous and higher temperature assemblages due to magnetite and Fe3+-bearing antigorite breakdown at <550°C and 700°C, respectively. The presence of pyrite in serpentinite, which transforms to pyrrhotite below 450°C, imposes a release of ¼ of initial sulfur, in H2S form. The presence of magnetite and pyrite in serpentinite, is crucial and responsible for the production of highly oxidized fluids and volatile sulfur species, which can be transported from the subducting slab into the mantle wedge. Application of results, obtained in the present study, to nature demonstrates that fluids rising from subducting slab are responsible for oxidation of overlying mantle, and in addition, magnetite and antigorite breakdown which occurs with at least 100°C difference may cause a release of chemically different fluids at shallow (low-T) and deep (high-T) parts of subduction
3
McIntyre, Todd Ian. "Analysis of selected ions in Allium cratericola growing on serpentine and non-serpentine soil." Scholarly Commons, 1991. https://scholarlycommons.pacific.edu/uop_etds/2212.
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The primary problems which plants growing on serpentine soil must overcome are high magnesium concentrations and calcium deficiency. The ability of Allium cratericola to successfully exploit both serpentine and non-serpentine habitats may be due to physiological adaptations which compensate for unusual mineral composition of the soil. Although the Table Mountain soil is described as non serpentine, it bears ionic similarities to the three serpentine soils studied in this investigation.
With the advent of modern biochemical techniques in plant physiology, there are ample opportunities to expand on past work concerning plant growth on serpentine soil. Investigations into the biochemical nature of tolerance mechanisms, especially those involving the mechanics of ion transport and translocation, could further elucidate the nature of plant growth on this soil type.
4
Can, Semra. "Characterization Of Serpentine Filled Polypropylene." Phd thesis, METU, 2008. http://etd.lib.metu.edu.tr/upload/3/12609434/index.pdf.
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ABSTRACT
CHARACTERIZATION OF SERPENTINE FILLED POLYPROPYLENE
Can, Semra
Ph.D., Department of Polymer Science and Technology
Supervisor: Prof. Dr. Teoman Tinçer March 2008, 158 pages In this study, the aim is to prepare polypropylene (PP)/serpentine composites and study their mechanical, thermal and morphological properties. Another objective is to explore whether it is possible to have PP/serpentine nanocomposites with melt intercalation method by using the advantage of the layer silicate structure of serpentine. The most widely used fillers in PP are talc and mica which belong to the phyllosilicates group of silicate minerals. So far, there has been almost no study employing serpentine as filler in either any polymers or PP, although it also belongs to the same group of minerals as talc and mica. Accordingly, it was planned to divide the work into the study of two groups. In group 1, for the compositions with 2, 5, 10 and 20 wt% serpentine, the particulate filler effects of serpentine both alone and in the presence of surface treatments with hydrochloric acid (HCl) and silane coupling agent (SCA) were investigated. The most impressive results in terms of static and dynamic mechanical properties were achieved with SCA rather than HCl. When the effect of serpentine without any treatment is considered, reinforcing effect of it can easily be observed without deteriorating the composite properties even at high filler loadings. In group 2, the nanofiller effects of serpentine in 2 and 5 wt% filled compositions by modification of both the filler and the matrix were aimed to be examined with melt intercalation method. In addition to HCl and SCA treatments, maleic anhydride grafted polypropylene (PP-g-MA) and quaternary ammonium salt (QAS) of cetyl-trimethyl-ammonium bromide were used as compatibilizer and intercalating agent, respectively. While the amount of QAS was kept constant, different percentages of compatibilizer were employed. The presence of QAS and PP-g-MA further improved the properties with respect to group 1 members. Interestingly, the percentage strain at break values did not decrease as much as group 1 compositions with the same filler content. It can be concluded that partial intercalation of group 2 compositions was achieved, according to the X-ray and TEM results. Keywords: Serpentine, PP/serpentine composites, SCA, PP-g-MA, serpentine nanocomposites
5
Town, Christopher Albert. "Instream aeration of the Serpentine River." Thesis, University of British Columbia, 1986. http://hdl.handle.net/2429/26335.
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Urban encroachment and intensive agricultural pursuits within the Serpentine-Nicomekl watershed (in proximity to Vancouver, B.C.) have caused a number of serious fish kills on the Serpentine River since 1980. Low dissolved oxygen levels were responsible for these kills.
This study investigated some of the dynamic chemical and biological relationships within the river, as well as artificial aeration as a pollution abatement or in-situ improvement measure. Weekly sampling from July to December, 1985, inclusive, established a solid data base from which inciteful interrelationships were deduced. A strong correlation between chlorophyll-a and dissolved oxygen levels supported the hypothesis that, algae blooms dying in the Fall, create a massive oxygen demand. A prototype, (457 m) artificial aeration line was designed, installed and monitored to evaluate its potential for alleviating low dissolved oxygen conditions experienced in the Fall periods. The aeration system operated successfully during September, October and November of 1985; however, because of ideal weather conditions, dissolved oxygen levels never dropped below 7.3 mg/L, so the opportunity to evaluate in-situ oxygen transfer did not arise in 1985. Nevertheless, the data base generated supports the use of the prototype aeration unit as a means of "upgrading" a stretch of river subject to periodic, low, dissolved oxygen levels. Expansion of the system, to include other critical stretches of the Serpentine River, is strongly recommended.Applied Science, Faculty of
Civil Engineering, Department of
Graduate
6
Potts, Ian. "Particle Redistribution in Serpentine Engine Inlets." The Ohio State University, 2020. http://rave.ohiolink.edu/etdc/view?acc_num=osu1595542100917769.
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7
Hughes, Ruth. "Serpentine tolerance in the Mimulus guttatus complex." Thesis, University of Exeter, 1999. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.286489.
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8
Zhang, Lixin. "Dynamic analysis of viscoelastic serpentine belt drive systems." Thesis, National Library of Canada = Bibliothèque nationale du Canada, 1999. http://www.collectionscanada.ca/obj/s4/f2/dsk1/tape8/PQDD_0021/NQ45747.pdf.
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9
Laker, Travis S. "Secondary flows in a rotating serpentine circular duct." Thesis, Georgia Institute of Technology, 2001. http://hdl.handle.net/1853/15898.
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10
Alvarez, Silva Mayeli. "Surface chemistry study on the pentlandite- serpentine system." Thesis, McGill University, 2011. http://digitool.Library.McGill.CA:80/R/?func=dbin-jump-full&object_id=97112.
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Interaction with MgO-minerals is one mechanism suspected to reduce selectivity in flotation of pentlandite from ultramafic ore. Understanding the surface chemistry of the minerals involved will lead to improved flotation conditions that maximize flotation selectivity. The first part of the thesis compares isoelectric point (i.e.p.) and point of zero charge (p.z.c.) determined using Mular-Roberts [M-R] titration technique of MgO-minerals chlorite, serpentine and talc. The M-R technique was unsuccessful with talc, attributed to Mg2+ acting as potential determining ion. For serpentine and chlorite, respectively, p.z.c. was pH 4.3 and 4.6 and i.e.p. pH 3.2 and <3. Dispersion index (DI) for chlorite suggested that aggregation/dispersion is controlled by both; serpentine remained dispersed, possibly due to hydration effects.The second part determines surface properties of pentlandite and serpentine isolated from an ultramafic ore. Zeta potential measurements were made on minerals alone and as mixtures with either indifferent electrolyte or supernatant derived from an ore suspension as background. Individual mineral results anticipated interaction due to electrostatic attraction. This was confirmed in the mixed mineral case, with Mg(OH)2 precipitate interaction as an additional factor. Scanning electron microscopy validated the findings.Aggregation/dispersion was determined by turbidimetry using a light scattering technique and optical microscopy. The effect of selected factors on aggregation/dispersion of pentlandite and serpentine was investigated by a design of experiment (DOE). Concentration of carboxymethyl cellulose, CMC, and the interaction between CMC and pH were the important factors. Contact angle measurements explored effects of several factors on pentlandite hydrophobicity and, using a DOE, small-scale flotation was used to investigate effects on pentlandite floatability. The pH was the most important factor, acidic pH increasing both hydrophobicity and floatability. Copper activation enhanced both properties, as well; magnesium affected hydrophobicity at alkaline pH, but it did not show significant effect on floatability; serpentine was detrimental to the process; and CMC was capable of partially restoring the hydrophobicity and floatability of pentlandite depressed with serpentine.L'interaction de la pentlandite avec des minéraux d'oxide de magnésium (MgO-) est soupçonnée d'être à l'origine de la sélectivité réduite de la pentlandite dans les procédés de flottation de minerais ultrabasiques. Une meilleure compréhension de la chimie de surface des minéraux impliqués devrait mener à l'amélioration des conditions de flottation qui en maximisent la sélectivité. La première partie de la thèse compare le point isoélectrique (p.i.e) et le point de charge nulle (p.c.n), déterminés à l'aide de la technique de titrage Mular-Roberts [M-R], de minéraux d'oxide de magnésium tels que la chlorite, la serpentine et le talc. Dans le cas du talc, la technique M-R a échoué, probablement dû aux ions Mg2+ qui jouent le rôle d'ions déterminateurs de potentiel. Dans le cas de la serpentine et de la chlorite, les p.c.n. ont été déterminés à pH 4,3 et 4,6 respectivement et les p.i.e à pH 3,2 et <3 respectivement. Des tests de décantations ont suggéré que l'agrégation/dispersion observée pour la chlorite était contrôlée à la fois par le p.c.n et le p.i.e ; la serpentine au contraire est restée dispersée, possiblement dû à des effets d'hydratation. La deuxième partie détermine les propriétés de surface de la pentlandite et de la serpentine isolées à partir d'un minerai ultrabasique. Des mesures du potentiel zêta ont été effectuées sur les minéraux seuls et mélangés en présence d'un électrolyte, indifférent dans un cas et surnageant dans l'autre cas, préparé à partir d'une suspension de minerai utilisée comme milieu d'étude. Les résultats relatifs aux minéraux individuels et en particulier les forces d'attraction électrostatique observables ont permis d'anticiper leur interaction. Cette hypothèse a été confirmée dans le cas des minéraux mélangés, étant après avoir pris en compte l'interaction de précipités de Mg(OH)2 comme facteur additionnel. Des observations au microscope électronique à balayage ont permis de valider les résultats. L'agrégation/dispersion a été déterminée par décantation en utilisant des techniques de lumière diffuse et de microscopie optique. L'effet de certains facteurs sur l'agrégation/dispersion de la pentlandite et de la serpentine a été étudié sur la base d'un plan d'expériences (PE). Entre autres, la concentration en carboxymethyl cellulose (CMC) et l'interaction entre le CMC et le pH ont été considérés comme des facteurs importants. Des mesures d'angle de contact ont permis d'explorer l'hydrophobicité de la pentlandite et, à l'aide d'un PE, une étude de flottation à petite échelle a été réalisée pour investiguer la flottabilité de la pentlandite. Les résultats ont montrés que le pH était le facteur le plus important, un pH acide ayant pour effet d'augmenter à la fois l'hydrophobicité et la flottabilité. L'ajout de cuivre a également permis de renforcer ces deux propriétés par un effet d'activation; la présence de magnésium au contraire a affecté l'hydrophobicité de la pentlandite à pH alcalin mais n'a pas eu d'effet significatif sur ses propriétés de flottabilité; la présence de serpentine s'est trouvée être préjudiciable au procédé mais l'utilisation de CMC a pu être utilisée afin de restaurer partiellement l'hydrophobicité et la flottabilité de la pentlandite diminuées par la présence de la serpentine.
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Kong, Lingyuan. "Coupled belt-pulley mechanics in serpentine belt drives." The Ohio State University, 2004. http://rave.ohiolink.edu/etdc/view?acc_num=osu1069789616.
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Vieira, Kely Regina Maximo [UNESP]. "Estudo da reação de dissolução de serpentinitos brasileiros para uso em processo de captura de carbono." Universidade Estadual Paulista (UNESP), 2016. http://hdl.handle.net/11449/137863.
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Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)
Nesta dissertação, investiga-se a reação de dissolução ácida de rochas silicatos brasileiras visando a aplicação em um processo de captura e sequestro de carbono denominado por Carbonatação Mineral. Na carbonatação mineral pela rota indireta utiliza-se ácidos, bases ou sais de amônia para a extração do magnésio, principalmente, presente na rocha silicato a fim de a formar carbonatos estáveis. Destaca-se que a etapa de dissolução ácida é uma fase limitante para o processo de carbonatação mineral, principalmente por apresentar baixa taxa de reação. O objetivo deste trabalho é utilizar o ácido clorídrico (HCl) e dois serpentinitos oriundos do estado de Goiás e Minas Gerais para avaliar o processo de dissolução ácida. Os serpentinitos foram preparados, selecionados e caracterizados para determinar a composição elementar. Aplicou-se o planejamento experimental e arranjo L9 de Taguchi na avaliação dos fatores que influenciam o processo de dissolução, tais como, temperatura do processo, concentração do HCl, tamanho médio das partículas da matéria prima e excesso de ácido. Os 9 ensaios previstos na matriz de planejamento para cada serpentinito foram executados de forma aleatória e em duplicata. Os produtos finais, resíduo sólido retido no papel filtro e solução contendo os elementos de interesse, foram analisados obtendo-se a composição elementar das soluções. Considerando-se os testes previstos na matriz de planejamento, a condição de melhor ajuste para extração de Mg foi utilizando-se a granulometria média de 69 µm, temperatura de 70°C, HCl 2 M com quatro vezes a quantidade estequiométrica. Nas soluções foram obtidas as concentrações de 29 % e 76 % de Mg para as amostras de serpentinito de Minas Gerais e de Goiás, respectivamente. Foram também avaliadas as melhores condições para extração de Fe e Ca e menor extração de Si, uma vez que o Si diminui a conversão no processo. Na análise estatística verificou-se que para a amostra de Minas Gerais todos os fatores apresentaram significância. No caso da a amostra de Goiás a temperatura no nível alto (70°C) apresentou maior significância.
In this dissertation, acid dissolution reaction of Brazilian silicate rocks was investigated aiming the implementation in a Carbon Capture and Storage process named Mineral Carbonation. In the mineral carbonation by indirect route, acids, bases or salts of ammonia are used for magnesium extraction, mainly, present in the silicate rock in order to form stable carbonates. It is noteworthy that the acid dissolution step is a limiting step in the process of mineral carbonation, mainly because of its low reaction rate. The objective of this study was to use hydrochloric acid (HCl) and two serpentinites from Goiás and Minas Gerais states to evaluate the acid dissolution process. The serpentinites were prepared, selected, and characterized to determine the elemental composition. The L9 experimental design and Taguchi arrangement were applied to evaluate the factors that influence in the dissolution process, such as process temperature, HCl concentration, average particle size of material and acid excess. The nine tests prescribed in planning matrix for each serpentinite were performed at random and in duplicate. The end products, solid residue retained on the filter paper and the solution containing the elements of interest were analyzed obtaining the elemental composition of the solutions. Considering the prevised tests on planning matrix, the best adjust condition for Mg extraction was using the average particle size of 69 µm temperature of 70°C, 2 M HCl with four times the stoichiometric amount. In the solutions, the concentrations obtained were 29 % and 76 % Mg for samples of serpentinite from Minas Gerais and Goiás, respectively. The best conditions for the extraction of Fe and Ca and lower extraction of Si were evaluated, since Si decreases the conversion in the process. In the statistical analysis was found that in Minas Gerais sample all factors were significant. In the case of Goiás sample, the temperature at the high level (70°C) showed greater significance.
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Egger, Brigitte Egger Brigitte. "Végétation et stations alpines sur serpentine près de Davos /." [S.l.] : [s.n.], 1993. http://e-collection.ethbib.ethz.ch/show?type=diss&nr=10343.
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Yamakawa, Emi. "Study of serpentine acceleration in zero-chromatic FFAG accelerators." 京都大学 (Kyoto University), 2013. http://hdl.handle.net/2433/174929.
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Chong, Li Yean. "Annular two phase flow in straight and serpentine channels." Thesis, University of Nottingham, 2003. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.403700.
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Ferrar, Anthony Maurice. "Measurements of Flow in Boundary Layer Ingesting Serpentine Inlets." Thesis, Virginia Tech, 2011. http://hdl.handle.net/10919/36408.
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Highly integrated airframe-propulsion systems featuring ingestion of the airframe boundary
layer oer reduced noise, emissions, and fuel consumption. Embedded engine systems are
envisioned which require boundary layer ingesting (BLI) serpentine inlets to provide the
needed air
ow to the engine. These inlets produce distorted
ow proles that can cause
aeromechanical, stability, and performance changes in embedded engines. Proper design
of embedded engine systems requires understanding of the underlying
uid dynamics that
occur within serpentine inlets.
A serpentine inlet was tested in a specially designed wind tunnel that simulated boundary
layer ingestion in a full-scale realistic environment. The measured total pressure proles at
the inlet and exit planes of the duct, and the static pressure distributions along the walls
provided useful data related to the
ow in BLI serpentine inlet systems. A bleed
ow control
system was tested that utilized no more than 2% of the total inlet
ow. Two bleed slots
were employed, one near the rst bend of the S-duct and one near second. The bleed system
successfully reduced inlet distortions by as much as 30%, implying improvements in stall
margin and engine performance.
Analysis of the wake shape entering the S-duct showed that the airframe and inlet duct are
both important components of a wake-ingesting inlet/diusion system. Shape eects and
static pressure distributions determined
ow transport within the serpentine inlet. Flow
separation within the S-duct increased distortion at the engine inlet plane. Discussion
of airframe/inlet/engine compatibility demonstrates that embedded engine systems require
multi-disciplinary collaborative design eorts. An included fundamental analysis provides
performance estimates and design guidelines. The ideal airframe performance improvement
associated with wake-ingestion is estimated.Master of Science
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Robinson, S. Thomas. "Impacts of agricultural drainage and an assessment of diffused aeration in the Serpentine River, British Columbia." Thesis, University of British Columbia, 1988. http://hdl.handle.net/2429/28513.
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Urban expansion of the City of Vancouver has resulted in increased land development of the municipality of Surrey, and more intensive agriculture on the remaining farmland. From 1980 to 1984 five different fish kills in the Serpentine River attributed to low dissolved oxygen were thought to be caused by a combination of agricultural discharges, high autumn water temperatures, as well as rainfall and river flow patterns. In 1985 an experimental instream aeration system was installed in a lower reach of the river in an attempt to provide additional oxygen during the critical autumn period.
This study was undertaken to determine the extent of the agricultural drainage discharge problem. Weekly sampling from July to December, 1987, revealed that organic pollutional loading from dairy farms was high. Nutrients loadings in the river supported a heavy algal growth which resulted in an oxygen deficit during autumn algal die-off and decay. Although the flushing of farm ditches normally exerts an additional oxygen demand on the river, this was not observed in 1987 because the major autumn rains began on Oct 30, and lower water temperatures prevented a rapid exertion of the biodegradable oxygen demand.
Implementation of source control of farm animal wastes is strongly recommended, along with a program of public education on conservation and management of natural habitat. Harvesting of filamentous algae in the river may eventually prove necessary for successful rehabilitation as diffused river aeration appears to be having a very small effect.Applied Science, Faculty of
Civil Engineering, Department of
Graduate
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Ferrand, Thomas. "Reproduction expérimentale d'analogues de séismes mantelliques par déshydratation de l'antigorite & Comparaison à des pseudotachylites naturelles." Thesis, Paris Sciences et Lettres (ComUE), 2017. http://www.theses.fr/2017PSLEE011/document.
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Les séismes intermédiaires (30-300 km) ont été largement documentés dans les plaques océaniques en subduction mais leur mécanisme physique reste énigmatique. Des séismes se produisent dans les plans de Wadati-Bénioff supérieur et inférieur. Ce dernier se situe dans le manteau lithosphérique plongeant, 15 à 40 km sous l’interface de subduction, et est considéré dû à la déshydratation de l’antigorite, serpentine de haute température.Pour tester cette hypothèse et comprendre quel mécanisme est en jeu dans le plan inférieur, des expérimentations (Griggs et D-DIA) et une étude de terrain (Balmuccia, Italie) ont été effectuées.Des péridotites artificielles ont été déshydratées pendant leur déformation dans des conditions typiques du manteau supérieur (1 à 3.5 GPa). Des émissions acoustiques sont enregistrées dans des échantillons comportant 5 %vol. d’antigorite. Les microfailles associées sont scellées par des pseudotachylites contenant des fluides, montrant que la déstabilisation de l’antigorite a déclenché une rupture dynamique et la fusion de l’olivine sur la surface de faille. Ces résultats mènent à l’établissement d’un model dans lequel un transfert de contrainte induit par déshydratation, et non par surpression de fluides, est le déclencheur de la fragilisation des roches du manteau.Parallèlement, une pseudotachylite de la péridotite de Balmuccia révèle l’enregistrement de l’histoire du glissement d’un séisme fossile de magnitude Mw > 6. La lubrification co-sismique est complète et transitoire, car le magma peut rapidement s’écouler dans les fentes en tension lors du passage du front de rupture, peut-être plus vite qu’il n’est produit. L’aspiration du magma mènerait à un refroidissement permettant le rétablissement de la résistance et l’arrêt du glissement.Cette pseudotachylite naturelle, un million de fois plus grande que son analogue expérimental, s’est formée dans les mêmes conditions de pression et de température. La grande similitude entre ces failles sur le terrain et au laboratoire indique un mécanisme similaire, et donc que les expériences montrent un mécanisme de rupture représentatif de ce qui se passe dans la nature. D’autre part, de l’H2O, trouvée fossilisée dans la pseudotachylite, était présente pendant la rupture sismique.Ce travail réconcilie des décennies d’études semblant contradictoires sur le lien entre séismes mantelliques et déshydratation de l’antigorite. À une certain échelle, une fraction d’antigorite de seulement 5 %vol. suffit à déclencher une sismicité, qui pourrait finalement être vue comme un indicateur du degré d’hydratation dans le manteau lithosphériqueIntermediate-depth earthquakes (30-300 km) have been extensively documented within subducting oceanic slabs but their physical mechanisms remain enigmatic. Earthquakes occur both in the upper and lower Wadati-Benioff planes. The latter is located in the mantle of the subducted oceanic lithosphere, 15-40 km below the plate interface, and is thought to be due to the dehydration of antigorite, the high-temperature serpentine.To test this hypothesis and understand which mechanism is at play in the lower plane, both experiments (Griggs and D-DIA) and field work (Balmuccia, Italy) have been performed.Artificial peridotites were dehydrated during deformation at upper mantle conditions. Between 1 and 3.5 GPa, acoustic emissions are recorded in samples with only 5 vol.% antigorite. Associated microfaults are sealed by fluid-bearing pseudotachylytes, showing that antigorite destabilization triggered dynamic shear failure and frictional melting of olivine. These results lead to a model in which dehydration-induced stress transfer, rather than fluid overpressure, is the trigger of mantle rocks embrittlement.Simultaneously, a pseudotachylyte from the Balmuccia peridotite reveals the recorded sliding history of an ancient Mw > 6 earthquake. The co-seismic fault lubrication is complete and transient, as the melt could rapidly flow into tensile fractures generated by the rupture front pass through, possibly faster than it is produced. Melt suction within the fractures led to rapid cooling and may have promoted strength recovery and sliding arrest.This natural pseudotachylyte, one million times larger than the experimental ones, has formed at the same pressure and temperature. The high similarity between those experimental and natural faults indicates a similar mechanism at both scales, and thus that the experiments show a rupture mechanism representative of what happens in nature. Furthermore, H2O, found fossilized in the pseudotachylyte, was somehow present during the seismic rupture.This work reconciles decades of apparently contradictory studies on the possible link between mantle earthquakes and serpentine dehydration. At a certain scale, an antigorite fraction as low as 5 vol.% is sufficient to trigger seismicity, which could therefore ultimately be seen as an indicator for the degree of hydration in the lithospheric mantle
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Kumar, Abhinav. "Flow control optimization in a jet engine serpentine inlet duct." [College Station, Tex. : Texas A&M University, 2007. http://hdl.handle.net/1969.1/ETD-TAMU-1399.
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Alakoc, Can Mustafa. "Preparation And Characterization Of Micron Size Serpentine Filled Abs Composite." Master's thesis, METU, 2008. http://etd.lib.metu.edu.tr/upload/12610142/index.pdf.
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Micron size non-treated / silane coupling agent (SCA) treated serpentine filled acrylonitrile-butadiene-styrene (ABS) composite preparation and characterization of composites in terms of mechanical, thermal, flow properties and morphology were studied in this work. First step of the study was the size reduction of the as collected serpentine mineral. Secondly, three types of silane coupling agent treatments were applied to serpentine which were gamma-methacryloxypropyltrimethoxysilane (A-174), beta-(3,4-epoxycyclohexyl)-ethyltrimethoxysilane (A-186) and gamma-mercapto-propyltrimethoxysilane (A-189). Non-treated and three different types of SCA treated serpentine minerals were melt mixed with ABS. Non-treated serpentine filled ABS composites had the serpentine weight fractions of 2%, 5%, 10% and 20%. On the other hand, SCA treated ones had serpentine weight fractions of 2%, 5% and 10%.
Morphological analysis showed that SCA treatment was partly effective in interface interaction enhancement and A-186 gave the best results according to micrographs. There wasn’
t any critical mechanical property loss up to 20% serpentine addition. Tensile tests revealed that SCA treatment increased the yield strength values of composites compared to non-treated serpentine filled composites. In accordance with morphological study, best result was obtained from 5% A-186 treated serpentine filled ABS as 12.9% improvement in yield strength value. Percent elongation at break values were increased with filler addition and greatest increase was observed in A-189 treated samples. Serpentine addition had no net effect on Young&
#8217
s Modulus values. According to the impact testing results, A-189 treated samples had improved toughness compared to non-treated samples in accordance with elongation at break values. However increasing filler content resulted with decrease in impact strength values. DSC analysis showed that glass transion temperatures, especially for SCA treated samples, were decreased compared to neat ABS with filler addition. This result suggests that SCA may had the plasticizing effect on the composite. Flow properties of composites were not different from neat ABS up to 2% addition, when the filler concentration was further increased melt flow index values were dramatically decreased.
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Maasdorp, Lynndle Caroline. "Temperature proton exchange membrane fuel cells in a serpentine design." Thesis, University of the Western Cape, 2010. http://etd.uwc.ac.za/index.php?module=etd&action=viewtitle&id=gen8Srv25Nme4_1316_1307961639.
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The aim of my work is to model a segment of a unit cell of a fuel cell stack using numerical methods which is classified as computational fluid dynamics and implementing the work in a commercial computational fluid dynamics package, FLUENT. The focus of my work is to study the thermal distribution within this segment. The results of the work aid in a better understanding of the fuel cell operation in this temperature range. At the time of my investigation experimental results were unavailable for validation and therefore my results are compared to previously published results published. The outcome of the results corresponds to this, where the current flux density increases with the increasing of operating temperature and fixed operating voltage and the temperature variation across the fuel cell at varying operating voltages. It is in the anticipation of determining actual and or unique material input parameters that this work is done and at which point this studies results would contribute to the understanding high temperature PEM fuel cell thermal behaviour, significantly.
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Bharadwajh, Rahul. "MEASUREMENTS IN A ROTATING SERPENTINE DUCT WITH MULTIPLE RIB ARRANGEMENTS." UKnowledge, 2003. http://uknowledge.uky.edu/gradschool_theses/308.
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The effect of rotation on flow in a gas turbine blade cooling duct model is investigated experimentally. The present work consists of velocity measurements at different locations in a test section with a 180° bend with ribs on one wall. Three geometric rib parameters are considered; rib-rib spacing, rib orientation angle and rib blockage ratio. PIV is used for flow visualization and analysis. Along with the clean duct measurements, ribs with blockage ratios, b/h, of 0.25 and 0.125 were considered. The b/h = 0.25 cases have been comprehensively analyzed while the b/h = 0.125 cases have been studied at the post-bend region of the duct only. Reynolds number considered is in the range of approximately 5000-40,000 and the rotation speed is varied for a rotation number from 0 to 7. It is observed that rotation has a significant effect on secondary flows within the rotating duct. For blockage ratio, b/h = 0.25, at a constant Re and Ro, the RMS of fluctuations of velocity do not show large spatial variations with ribs or rib orientations. At higher Re, the value decreases in comparison to the low Re cases. The kinetic energy of fluctuations increases due to the presence of ribs, indicating better heat transfer for the ribbed duct, but do not show large variations with rib orientation angle. The fluctuations and kinetic energy show maximum values at the post-bend regions of the duct. The velocity fields and PDFs show a possible cause for e°cient heat transfer for the 45° rib arrangement as compared with the 90° rib cases. At high Ro, the absolute value of circulation has a large increase at the post-bend and thereafter there is a gradual decay at the exit for all cases. The ribs with blockage ratio of b/h = 0.125 showed no marked changes in circulation with changes in rib orientation angle, thus implying that the rib blockage plays a role in the generation of secondary flows, particularly in conjunction with rotation.
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Harrison, Neal A. "Active Flow Control of a Boundary Layer Ingesting Serpentine Diffuser." Thesis, Virginia Tech, 2005. http://hdl.handle.net/10919/34163.
Full textAbstract:
The use of serpentine boundary layer ingesting (BLI) diffusers offers a significant benefit to the performance of Blended Wing Body aircraft. However, the inherent diffuser geometry combined with a thick ingested boundary layer creates strong secondary flows that lead to severe flow distortion at the engine face, increasing the possibility of engine surge. This study investigated the use of enabling active flow control methods to reduce engine-face distortion.
An ejector-pump based system of fluidic actuators was used to directly manage the diffuser secondary flows. This system was modeled computationally using a boundary condition jet modeling method, and tested in an ejector-driven wind tunnel facility. This facility is capable of simulating the high-altitude, high subsonic Mach number conditions representative of BWB cruise conditions, specifically a cruise Mach number of 0.85 at an altitude of 39,000 ft.
The tunnel test section used for this experiment was designed, built, and tested as a validation tool for the computational methods. This process resulted in the creation of a system capable of efficiently investigating and testing the fundamental mechanisms of flow control in BLI serpentine diffusers at a minimum of time and expense.
Results of the computational and wind tunnel analysis confirmed the large potential benefit of adopting fluidic actuators to control flow distortion in serpentine BLI inlets. Computational analysis showed a maximum 71% reduction in flow distortion at the engine face through the use of the Pyramid 1 ejector scheme, and a 68% reduction using the Circumferential ejector scheme. However, the flow control systems were also found to have a significant impact on flow swirl. The Pyramid 1 ejector scheme was found to increase AIP flow swirl by 64%, while the Circumferential ejector scheme reduced flow swirl by 30%. Computational analyses showed that this difference was the result of jet interaction. By keeping the jet flows separate and distinct, the diffuser secondary flows could be more efficiently managed. For this reason, the most practically effective flow control scheme was the Circumferential ejector scheme.
Experimental results showed that the computational analysis slightly over-predicted flow distortion. However, the trends are accurately predicted despite slight variances in freestream Mach number between runs and a slightly lower tested altitude.Master of Science
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Zafaranloo, Ali. "Kinetics of Magnesium Extraction from Activated Serpentine by Carbonic Acid." Thesis, The University of Sydney, 2015. http://hdl.handle.net/2123/14531.
Full textAbstract:
Ex situ mineral carbonation heavily depends on the ability of cations (e.g., Mg2+) to form stable carbonates. The abundant serpentine minerals contain sufficient magnesium to fill this role. Serpentine partially dehydroxylated by thermal pre-treatment, which has a nearly amorphous state (meta-serpentine), has been shown to enhance overall carbonation yield. However, the dissolution kinetics of meta-serpentine under the carbonic acid system remains largely unresolved within the literature. In this thesis, the kinetics of magnesium extraction from thermally activated serpentine under the CO2-H2O system was investigated for the purpose of identifying the underlying rate-limiting mechanisms. The extraction rates of magnesium and silica from thermally activated serpentine were measured over a wide range of conditions, covering different reaction temperatures (303–473 K), pressures (10–160 bar), mass loading factors (0.03–1 min), and particle sizes (20–180 μm) using a continuous fluidised bed reactor under the saturated CO2-H2O system. Extraction of silica almost always followed the equilibrium solubility of amorphous silica. Magnesium is believed to be released by the protons associated with the MgO-CO2-H2O equilibria. The kinetic implications of all the measured magnesium extraction rates were evaluated using a far-from-equilibrium pH dependence mechanism. At undersaturated conditions, the remarkable unifying rate behaviour across various experiments implied that the extraction of magnesium is more-or-less proportional to the bulk equilibrium concentration of protons. In addition, the associated term for activation energy with the rate law appeared negligible. At saturated conditions magnesium extraction was inhibited, which was attributed to precipitation of secondary phases in the porous substrate.
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Al-Neama, Ahmed Fouad Mahmood. "Serpentine minichannel liquid-cooled heat sinks for electronics cooling applications." Thesis, University of Leeds, 2018. http://etheses.whiterose.ac.uk/20318/.
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The increasing density of transistors in electronic components is leading to an inexorable rise in the heat dissipation that must be achieved in order to preserve reliability and performance. Hence, improving the thermal management of electronic devices is a crucial goal for future generations of electronic systems. Therefore, a complementary experimental and numerical investigation of single-phase water flow and heat transfer characteristics of the benefits of employing three different configurations of serpentine minichannel heat sink (MCHS) designs has been performed, to assess their suitability for the thermal management of electronic devices. These heat sinks are termed single (SPSMs), double (DPSMs) and triple path serpentine rectangular minichannels (TPSMs), and their performance is compared, both experimentally and numerically, with that of a design based on an array of straight rectangular minichannels (SRMs) in terms of pressure drop (ΔP), average Nusselt number (Nuavg) and total thermal resistance (Rth). The results showed that the serpentine channel bends are very influential in improving heat transfer by preventing both the hydrodynamic and thermal boundary layers from attaining a fully-developed state. The SPSM design provides the most effective heat transfer, followed by the DPSM and TPSM ones, both of which out-performed the SRM heat sink. The SPSM heat sink produced a 35% enhancement in Nuavg and a 19% reduction in Rth at a volumetric flow rate (Qin) of 0.5 l/min compared to the conventional SRM heat sink. These improvements in the heat transfer are, however, achieved at the expense of significantly larger ΔP. It was found that the incorporation of serpentine minichannels into heat sinks will significantly increase the heat-removal ability, but this must be balanced with the pressure drop requirement. Therefore, an experimental and numerical investigation of the benefit of introducing chevron fins has been carried out to examine the potential of decreasing pressure drop along with further thermal enhancement. This novel design is found to significantly reduce both the ΔP across the heat sink and the Rth by up to 60% and 10%, respectively, and to enhance the Nuavg by 15%, compared with the SPSM heat sink without chevron fins. Consequently, the design of the SPSM with and without chevron fins was then optimised in terms of the minichannel width (Wch) number of minichannels (Nch) and chevron oblique angle (θ). The optimisation process uses a 30 (without chevron fins) and 50 (with chevron fins) point Optimal Latin Hypercubes Design of Experiment, generated from a permutation genetic algorithm, and accurate metamodels built using a Moving Least Square (MLS) method. A Pareto front is then constructed to enable the compromises available between designs with a low pressure drop and those with low thermal resistance to be explored and appropriate design parameters to be chosen. These techniques have then been used to explore the feasibility of using serpentine MCHS and heat spreaders to cool GaN HEMTs.
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Johnson, Jesse Scott. "The Effects of Freestream Turbulence on Serpentine Diffuser Distortion Patterns." BYU ScholarsArchive, 2012. https://scholarsarchive.byu.edu/etd/3500.
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Serpentine diffusers have become a common feature in modern aircraft as they allow for certain benefits that are impossible with a traditional linear configuration. With the benefits, however, come certain disadvantages, namely flow distortions that reduce engine efficiency and decrease engine surge stability margins. These distortions are now being researched comprehensively to determine solutions for mitigating the adverse effects associated with them. This study investigates how varying the freestream turbulence intensity of the flow entering a serpentine diffuser affects the distortion patterns that are produced by the diffuser. Experiments were performed with a model serpentine diffuser on the Annular Cascade Facility of the Air Force Research Laboratory at Wright-Patterson Air Force Base. Hot wire anemometry was used to measure inlet turbulence, while static pressure probes located axially along the upper and lower surface of the model diffuser and total pressure probes located across the aerodynamic interface plane (AIP) were used to measure the distortion patterns of the flow passing through the diffuser. Varying levels of inlet freestream turbulence, ranging from 0 to 4%, were generated using square and round bar turbulence screens in three distinct test configurations. Axial static pressure measurements indicate that increasing turbulence slightly affects flow separation development downstream of the second turn. This effect is also seen at the AIP where the total pressure recovery increases with increasing level of inlet turbulence in the region of flow separation at the upper surface. The total pressure recovery along the lower surface is also seen to be increased with higher inlet turbulence. However, total pressure recovery increase across the entire AIP is almost negligible. Overall, the inlet freestream turbulence has a minor effect on the distortion patterns caused by the serpentine diffuser when compared with proven active inlet flow control methods.
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Haywood, Mark. "Venus in chairs : a neo-Darwinian analysis of classical beauty in art and its subsequent passage from art to design." Thesis, Royal College of Art, 2000. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.326050.
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Jansen, Nora Catharine Mary. "Vegetation ecology of Rawhide Hill, Toulumne County, California." Scholarly Commons, 1991. https://scholarlycommons.pacific.edu/uop_etds/2208.
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Tichenor, Nathan Ryan. "Particle image velocimetry in an advanced, serpentine jet engine inlet duct." Thesis, [College Station, Tex. : Texas A&M University, 2007. http://hdl.handle.net/1969.1/ETD-TAMU-1401.
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Kirk, Aaron Michael. "Active flow control in an advanced serpentine jet engine inlet duct." [College Station, Tex. : Texas A&M University, 2006. http://hdl.handle.net/1969.1/ETD-TAMU-1027.
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Atakan, Baris. "3-d Grasping During Serpentine Motion With A Snake-like Robot." Master's thesis, METU, 2005. http://etd.lib.metu.edu.tr/upload/3/12606887/index.pdf.
Full textAbstract:
In this thesis, we introduce our lasso-type grasping scheme. This 3-D lasso-type grasping scheme, different from the previously performed grasping schemes which are either planar or fixed base, is the novelty of our approach where the snake robot grasps an object with any of its body links which are at close proximity to the object while undergoing its serpentine motion with the remaining links and dragging the grasped object. Since our snake robot has the pitch motion for every link, we can ensure that the links do not run into each other as they wrap around the object. A lasso-type power grasp is then possible for our 15-link snake robot as seen in the simulation results of this thesis.
Furthermore we develop the kinematic and control models for lasso-type grasping and for dragging the grasped object to a desired state. This control model includes an adaptively changing feedback gain which prevents excessively large inputs to corrupt the serpentine locomotion control. According to our lasso-type grasping model, while the snake robot can grasp the object beginning with the any body link at close proximity of the object, the contact points can be controlled to generate the curvilinear grasping curve by using our lasso-type grasping procedure. For dragging the grasped object, we define a scheme which can determine the appropriate desired state to drag the grasped object to a desired position.
The stability of the grasped object is important to resist the disturbance forces as well as the force closure grasping is important to counteract the disturbance force. To analyze the stability of the lasso-type grasping, we introduce a stability model of lasso-type grasping based on contact stiffness matrices that faces the snake to regrasp when gone unstable.
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Anderson, Jason Mitchell. "Non-Intrusive Sensing and Feedback Control of Serpentine Inlet Flow Distortion." Diss., Virginia Tech, 2003. http://hdl.handle.net/10919/27120.
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A technique to infer circumferential total pressure distortion intensity found in serpentine inlet airflow was established using wall-pressure fluctuation measurements. This sensing technique was experimentally developed for aircraft with serpentine inlets in a symmetric, level flight condition. The turbulence carried by the secondary flow field that creates the non-uniform total pressure distribution at the compressor fan-face was discovered to be an excellent indicator of the distortion intensity. A basic understanding of the secondary flow field allowed for strategic sensor placement to provide a distortion estimate with a limited number of sensors. The microphone-based distortion estimator was validated through its strong correlation with experimentally determined circumferential total pressure distortion parameter intensities (DPCP).
This non-intrusive DPCP estimation technique was then used as a DPCP observer in a distortion feedback control system. Lockheed Martin developed the flow control technique used in this control system, which consisted of jet-type vortex generators that injected secondary flow to counter the natural secondary flow inherent to the serpentine inlet. A proportional-integral-derivative (PID) based control system was designed that achieved a requested 66% reduction in DPCP (from a DPCP of 0.023 down to 0.007) in less than 1 second. This control system was also tested for its ability to maintain a DPCP level of 0.007 during a quick ramp-down and ramp-up engine throttling sequence, which served as a measure of system robustness. The control system allowed only a maximum peak DPCP of 0.009 during the engine ramp-up. The successful demonstrations of this automated distortion control system showed great potential for applying this distortion sensing scheme along with Lockheed Martinâ s flow control technique to military aircraft with serpentine inlets.
A final objective of this research was to broaden the non-intrusive sensing capabilities in the serpentine inlet. It was desired to develop a sensing technique that could identify control efforts that optimized the overall inlet aerodynamic performance with regards to both circumferential distortion intensity DPCP and average pressure recovery PR. This research was conducted with a new serpentine inlet developed by Lockheed Martin having a lower length-to-diameter ratio and two flow control inputs. A cost function based on PR and DPCP was developed to predict the optimal flow control efforts at several Mach numbers. Two wall-mounted microphone signals were developed as non-intrusive inlet performance sensors in response to the two flow control inputs. These two microphone signals then replaced the PR and DPCP metrics in the original cost function, and the new non-intrusive-based cost function yielded extremely similar optimal control efforts.Ph. D.
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Harper, David Keneda. "Boundary Layer Control and Wall-Pressure Fluctuations in a Serpentine Inlet." Thesis, Virginia Tech, 2000. http://hdl.handle.net/10919/32841.
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In this thesis, the benefits of boundary layer control (BLC) in improving aerodynamic performance and engine stability were examined in a compact, serpentine inlet exhibiting flow separation. A 1/14-scale turbofan engine simulator provided the flow through the inlet. The inletâ s mass flow was measured to be 759 scfm (0.939 lbm/s) with an average throat Mach number of 0.23 when the simulator speed was 40 krpm. Boundary layer suction, blowing, and their combination were used to minimize the inletâ s flow separation. The effectiveness of the suction alone and the blowing alone was shown to be approximately equivalent, and the effectiveness of the combined use of both was seen to be better than either one by itself. With blowing and suction flowrates around 1% of the simulatorâ s core flow, the inletâ s distortion was lowered by 40.5% (from 1.55% to 0.922%) while the pressure recovery was raised by 9.7% (from 87.2% to 95.6%). With its reduction in distortion, BLC was shown to allow the simulator to steadily operate in a range that would have otherwise been unstable. Minimizing the flow separation within the inlet was shown to directly relate to measurements from flush-mounted microphones along the inlet wall: as the exit distortion decreased the microphone spectrum also decreased in magnitude. The strong relationship between the aerodynamic profiles and the microphone signal suggests that microphones may be used in an active flow control scheme, where the BLC effort can be tailored for different engine operating conditions. Unfortunately, the sensing scheme used in this experiment showed the microphone signal to continue to decrease even when the separation is overly compensated; therefore refinements must be made before it would be practical in a real application.Master of Science
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Chardot, Vanessa. "Réponse de Brassicacées hyperaccumulatrices à la disponibilité du nickel des sols ultramafiques." Thesis, Vandoeuvre-les-Nancy, INPL, 2007. http://www.theses.fr/2007INPL045N/document.
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Les plantes hyperaccumulatrices de métaux ont développé des mécanismes spécifiques de prélèvement de la fraction disponible des métaux du sol, conduisant à leur accumulation dans les parties aériennes. L’utilisation agronomique de ces plantes pourrait être une voie de dépollution des sols contaminés en métaux. Ce travail a pour objectif de contribuer à la compréhension des mécanismes chimiques et biologiques qui conditionnent l’accumulation du Ni par les plantes hyperaccumulatrices, en réponse à la disponibilité du métal dans le sol. Après observation du fonctionnement naturel du système sol ultramafique-plante hyperaccumulatrice, nous avons étudié, en laboratoire, l’altération de trois phases minérales nickélifères modèles communes des sols ultramafiques (chrysotile, smectite, goethite) soumises à l’influence de trois Brassicacées hyperaccumulatrices de Ni natives de sites de serpentine d’Europe (Leptoplax emarginata, Alyssum murale et Thlaspi caerulescens). Les résultats montrent que dans les sols ultramafiques, le Ni phytodisponible provient majoritairement de l’altération des minéraux nickélifères silicatés ferromagnésiens, hérités de la roche mère. Les hyperaccumulateurs ont un comportement différent en fonction de la disponibilité du Ni des sols. Dans les milieux à forte disponibilité du Ni, les hyperaccumulateurs accumulent le Ni proportionnellement à la disponibilité du Ni du milieu. Elles réduisent ainsi significativement la fraction de Ni initialement disponible du milieu, et ne semblent pas favoriser la dissolution des minéraux porteurs de Ni. A l’inverse, dans les milieux à faible disponibilité du Ni, la présence des hyperaccumulateurs accélère la dissolution de phases minérales nickélifères silicatées, en favorisant la solubilisation du métal. Dans ce cas la plante prélève la quasi-totalité du Ni solubilisé. Ces résultats sont essentiels à l’élaboration d’un modèle de culture qui permettra de faciliter l’application du procédé de phytoextraction du Ni à grande échelleMetal hyperaccumulator plants developed specific mechanisms to extract available metals from the soil and consequently accumulate them in aerial parts. The agronomic use of these plants for the decontamination of metal polluted soils is under study worlwide. This work was undertaken to better elucidate the chemical and physiological mechanisms that influence Ni accumulation by hyperaccumulators in response of Ni availability in soils. To answer these questions we undertook two approaches. Firstly, a site study to determine the natural functioning of the ultramafic soil-Ni hyperaccumulators system. Secondly, a lab-scale set of experiments that were designed to study the weathering of three ultramafic Ni-minerals (chrysotile, smectite, goethite) in the rhizosphere of three Ni-hyperaccumulating species naturally growing on European serpentine soils (Leptoplax emarginata, Alyssum murale et Thlaspi caerulescens). Results showed that, in ultramafic soils, phytoavailable Ni derives from the weathering of primary nickeliferous ferromagnesian silicates. Hyperaccumulators show a different behaviour depending of Ni availability in the environment of the culture. In environments showing high available Ni, hyperaccumulators accumulate Ni proportionally to Ni availability. In this way, they can significantly reduce the initially available fraction of Ni but do not seem to enhance the weathering of unavailable Ni forms. Contrarily, in environments with extremely low Ni availability, hyperaccumulators may strongly enhance the dissolution of nickeliferous silicate minerals and so favour Ni solubilisation. If so, hyperaccumulators absorb the majority of Ni solubilised. These results are of considerable interest for the elaboration of a crop model designed for the optimisation of the phytoextraction concept and high scale application
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Scoz, Eduardo. "Arquitetura efêmera: o repertório do arquiteto revelado em obras temporárias." Universidade de São Paulo, 2009. http://www.teses.usp.br/teses/disponiveis/16/16134/tde-10032010-162419/.
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Esta dissertação visa entender as implicações do projeto arquitetônico no momento da execução de obras efêmeras, bem como busca elucidar os paradigmas essenciais a este projeto frente ao estágio avançado de depredação dos meios naturais em que o planeta se encontra. Entretanto, ainda que com a escassez de referências bibliográficas sobre o tema, na busca por esse pensamento analisaremos três pavilhões de verão da Galeria Serpentine executados por arquitetos de grande importância no cenário atual acreditamos que o conceito em arquitetura fica plasmado na obra. A leitura desses objetos, organizados não verbalmente, necessita de um referencial capaz de elucidar a sintaxe do pensamento que o orienta, revelando através de dados icônicos e indiciais o repertório de seu projetista. Neste momento mostra-se fecunda a teoria da semiótica de Charles Sanders Peirce, não apenas para revelar o repertório do arquiteto e os paradigmas de projeto que o orientam, mas também para pesquisar de que maneira estes profissionais materializam seus pensamentos através da linguagem não-verbal da arquitetura. Por outro lado, o que se vê à exaustão em eventos comerciais é a utilização de semelhantes sistemas construtivos industrializados, dos quais o OCTANORM é o mais conhecido, o que garante a continuidade do processo moderno e a elevação da capacidade de montagem e desmontagem como valor principal da obra. As hipóteses aqui levantadas tomam estes sistemas como uma manifestação da continuidade e apontam para outras arquiteturas, ainda efêmeras, mas alheias a essa dinâmica e com especificidades que caracterizam um campo particular de estudo. A base epistemológica deste trabalho veicula muito a semiótica peirciana e a bibliografia fundamental que dá orientação à pesquisa tem origem na filosofia da arquitetura e na psicologia da percepção com diversos teóricos.This dissertation intends to understand the architectural project implications in the moment of the execution of ephemeral works, and tries to elucidate the essential paradigms to this project due to the advanced stage of depredation found within the planets natural resources. However, even facing a bibliographic shortage on the theme, searching this thought, we will analyze three summer pavilions inside Serpentine Gallery, executed by well-known architects we believe that the concept in architecture remains in this work. The reading of these objects, non-verbally organized, needs a reference capable of elucidating the thought syntax that guides it, revealing the designer repertory through iconic and inkling data. In this moment, Charles Sanders Peirces theory is shown to be abundant, not only to reveal the architectural repertory and the projects paradigms that guide it, but also to find the way that these professionals turn their thoughts into matter through non-verbal architectural language. On the other hand, what is exhaustively seen throughout commercial events is the use of similar industrialized constructive systems, from which OCTANORM is the most known, what guarantees the continuity of the modern process and the elevation of the mounting an dismounting capability as the main value of the work. The hypotheses raised in here consider these systems as a manifestation of continuity and point to other architectures, still ephemeral, but disconnected to this dynamic and owners of specificities that characterize a particular field of study. The basis of this work, regarding the use of epistemology, features peircians semiotics a lot and, the fundamental bibliography, that gives the research an orientation, has its origin in the architecture philosophy and in the psychology of perception defended by many theorists.
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Bultel, Benjamin. "Serpentinisation et carbonatation de la croûte Martienne." Thesis, Lyon, 2016. http://www.theses.fr/2016LYSE1004/document.
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Depuis ces 3 derniers milliards d'années l'eau liquide est extrêmement peu présente sur Mars. Cependant les multiples données disponibles sur la planète montrent des preuves d'une présence importante d'eau liquide depuis l'accrétion de la planète jusqu'à environ 3,7 milliards d'années. L'hypothèse dominante aujourd'hui est que Mars possédait une atmosphère plus dense (possiblement riche en CO2) au début de son histoire. Une grande partie de cette atmosphère et de l'eau auraient été perdu dans l'espace. Une autre hypothèse pour la diminution de la quantité d'eau liquide disponible et pour la diminution de l'atmosphère est le stockage d'eau et de CO2 dans la croûte. La croûte martienne est étudiée via les données de spectro-imagerie CRISM pour caractériser l'altération hydrothermale primitive de la planète. Des détections de serpentine et de carbonates confirment que le stockage d'une partie de l'eau et de l'atmosphère martienne a eu lieu. Des contraintes supplémentaires sont apportées par de la modélisation géochimique de la serpentinisation et de la carbonatation de la croûte martienne via les programme EQ3/6. L'importance de la serpentinisation et de la carbonatation de la croûte martienne est ainsi réévaluée. Les résultats permettent d'ouvrir la réflexion sur le rôle de la serpentinisation et de la carbonatation sur l'évolution de la quantité d'eau liquide disponible et sur l'évolution de l'atmosphère. En outre, les conditions thermodynamiques permettent d'apporter des contraintes sur le potentiel exobiologique de la croûte martienneOver the last 3 billion years liquid water has an extremely limited presence on Mars. However, the multiple data available on the planet show evidences of a significant presence of liquid water from the accretion of the planet until about 3.7 billion years. The prevailing hypothesis today is that Mars had a denser atmosphere (possibly rich in CO2) early in its history. Much of this atmosphere and water were lost in space. Another possibility for reducing the amount of liquid water available and the reduction of the atmosphere is the water storage of water and CO2 in the crust. The Martian crust is studied via CRISM spectro-imaging data to characterize the early hydrothermal alteration of the planet. Serpentine and carbonates of detections confirm that the storage of a portion of the water and the atmosphere of Mars occurred. Additional constraints are provided by the geochemical modeling of serpentinization and carbonation of the Martian crust through EQ3/6 programs. The importance of serpentinization and carbonation of the Martian crust is thus reassessed. The results allow to open the debate on the role of serpentinization and carbonation on the evolution of the liquid water available and the evolution of the atmosphere. In addition, the thermodynamic conditions help provide constraints on the exobiology potential of the Martian crust
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Al-Witry, Ali Qais. "Thermal performance of roll-bonded aluminium plate heat exchanger panels for use in ocean thermal energy conversion." Thesis, University of Nottingham, 1997. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.301658.
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Devouard, Bertrand. "Structure et croissance cristalline du chrysotile et des serpentines polygonales." Aix-Marseille 3, 1995. http://www.theses.fr/1995AIX30012.
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Le chrysotile, mineral du groupe des serpentines, presente une structure remarquable constituee par l'enroulement cylindrique de feuillets silicates. Nous proposons dans ce travail un modele cristallographique des reseaux cylindriques. Cette modelisation permet de discuter la structure et la symetrie des fibres de chrysotile selon une approche nouvelle. Les serpentines polygonales sont alors decrites comme une modification du reseau purement cylindrique du chrysotile, par individualisation de murs radiaux de dislocations. Ce modele rend compte de la polygonisation en 15 ou 30 secteurs, observee dans les echantillons naturels, et predit que chrysotile et serpentines polygonales possedent un axe de symetrie d'ordre cinq. La transformee de fourier numerique des nuds du reseau cylindrique permet de simuler la geometrie des cliches de diffraction electronique de sections de fibres perpendiculaires a l'axe. Les observations en microscopie electronique a transmission de serpentines tubulaires, en mode haute resolution et en diffraction electronique en aire selectionnee, supportent dans une large mesure le modele propose. De plus, l'observation de chrysotile synthetise par voie hydrothermale, permet l'etude de structures presentant un enroulement conique des feuillets. Les differents termes de l'enthalpie libre de formation d'un reseau cylindrique peuvent etre evalues a partir des donnees experimentales disponibles dans la litterature, ou a l'aide de calculs energetiques relevant de la modelisation moleculaire. On montre que la croissance du chrysotile est gouvernee par l'energie elastique liee a la courbure des feuillets, qui s'oppose a l'energie de volume. Cette caracteristique unique permet d'envisager d'utiliser les serpentines comme un traceur de l'ecart a l'equilibre du milieu de croissance
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Siddique, Waseem. "Design of Internal Cooling Passages: Investigation of Thermal Performance of Serpentine Passages." Doctoral thesis, KTH, Kraft- och värmeteknologi, 2011. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-47161.
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Gas turbines are used to convert thermal energy into mechanical energy. The thermal efficiency of the gas turbine is directly related to the turbine inlet temperature. The combustion and turbine technology has improved to such an extent that the operating temperature in the turbine inlet is higher than the melting temperature of the turbine material. Different techniques are used to cope with this problem. One of the most commonly used methods is internal cooling of the turbine blades. Conventionally air from the compressor is used for this purpose but due to higher heat capacity, steam can be used as coolant. This opens up the possibility to increase the gas temperature. In the case of a combined cycle power plant, its availability provides a good opportunity to be used as a coolant. The trailing edge of the gas turbine blades is an important region as it affects the aerodynamics of the flow. The aerodynamics demands a sharp and thin trailing edge to reduce profile losses. The conventional method is the release of a lot of cooling air though a slot along the airfoil trailing edge. However in the case of internal only cooling designs, the coolant is not allowed to leave the channel except from the root section to avoid mixing of the gas in the main flow path with the coolant and loss of cooling medium. The challenge is to design an inner cooling channel, with the cooling medium entering and leaving the blade at the root section, which reduces the metal temperatures to the required values without an increase of the profile losses and at acceptable cooling flow rate and pressure drop. This thesis presents Computational Fluid Dynamic (CFD) based numerical work concentrated firstly on the flow and heat transfer in two-pass rectangular channels with and without turbulator ribs. The aspect ratio of the inlet pass was reduced to accommodate more channels in the blade profile in chord-wise direction. Additionally, the divider-to-tip wall distance was varied for these channels. Their effect on heat transfer and pressure drop was studied for smooth as well as ribbed channels. It was followed by a numerical heat transfer study in the trapezoidal channel. Different RANS based turbulence models were used to compare the numerical results with the experimental results. Further, new designs to enhance heat transfer in the channel’s side walls (named as trailing edge wall) were studied. These include the provision of ribs at the trailing edge wall only, inline arrangement of ribs at the bottom as well as at the trailing edge wall and a staggered arrangement of these ribs. The final study was a conjugate heat transfer problem with an aim to propose the best internal cooling channel design to reduce the metal temperature of the trailing edge surface for the given thermal and flow conditions. A number of different options were studied and changes were made to get the best possible channel design. The results show that for a two-pass rectangular channel (both smooth and ribbed), the reduction in inlet channel aspect ratio reduces the pressure drop. For a smooth channel the reduction in the width of the inlet pass does not affect the heat transfer enhancement at the inlet pass and outlet pass regions. In case of ribbed channels, heat transfer decreases at the tip and bend bottom with decrease in the width of the inlet pass. Among different turbulence models used to validate numerical results against experimental results for case of trapezoidal channel, the low-Re k-epsilon model is found to be the most appropriate. Using the turbulence model that yields results that are closest to the experimental data, the staggered arrangement of ribs at the trailing edge wall is found to have maximum thermal performance. The results from the conjugate heat transfer problem suggest using steam as coolant if it is available as it requires less mass flow rate to get similar wall temperature values as compared to air at similar thermal and flow conditions. It is also found that staggered arrangement of ribs is the best option compared to others to enhance heat transfer in trailing edge of the gas turbine blade with the pressure drop in the cooling duct in the acceptable range.Gasturbiner används för att omvandla värmeenergi till mekanisk energi. Den termiska verkningsgraden för en gasturbin är direkt relaterad till turbinen inloppstemperatur. Förbrännings- och turbintekniken har förbättrats så mycket att gastemperaturen i turbininloppet är högre än smälttemperaturen för turbinmaterialet. Olika tekniker används för att hantera detta problem. En av de vanligaste metoderna är intern kylningen av turbinbladen. Konventionellt luft från kompressorn används för detta ändamål, men på grund av högre värmekapacitet kan ånga användas som kylmedel. Detta öppnar för möjligheten att höja gasens temperatur. Vid ett kombikraftverk, ger dess tillgänglighet ett bra tillfälle att användas som kylmedel. Den bakre delen av turbinbladen är ett viktigt område eftersom geometrin påverkar strömningen. Aerodynamiken kräver en skarp och tunn bakkant för att minska profilförlusterna. Den konventionella metoden för kylning av denna är att släppa ut en stor mängd kylluft genom en spalt längs bakkanten. Men i fallet med enbart inre kylning får kylmediet inte lämna skovelprofilen i strömningskanalen utan endast genom rotsektionen för att undvika blandning av förbränningsluften i turbinens strömningskanal med kylmediet och förlust av kylmedium. Utmaningen är att utforma en inre kylkanal, i vilken kylmediet kommer in och lämnar bladet i rotsnittet som är tillräckligt bra för att hålla metalltemperaturen på normala värden utan att öka profilförlusterna och med acceptabla kylluftflöden och tryckfall. Denna avhandling består av ett Computational Fluid Dynamics (CFD) baserat numeriskt arbetet koncentrerat på strömning och värmeöverföring först i två-pass rektangulära kanaler med och utan turbulensalstrande ribbor. Geometrin för inloppspassagen reducerades för att ge utrymme för fler kylkanaler inom bladets profil i kordans riktning. Dessutom varierades mellanväggens avstånd till toppväggen. Effekten på värmeöverföring och tryckfall studerades för båda kanalerna. Därefter följde en numerisk studie av värmeöverföringen i liknande men trapetsformade kanaler. Olika RANS baserade turbulensmodeller användes för att jämföra numeriska och experimentella resultat. Vidare har nya konstruktioner för att förbättra värmeöverföringen i kanalens sidoväggar och bakkant studeras. Dessa inkluderar turbulensribbor på enbart bakkantsväggen samt ribbor på såväl sidoväggar som på bakkantsväggen i linje med och förskjutna mot varandra. Den slutliga studien var ett sammansatt värmeöverföringsproblem bakkantens yta för ett visst angivet tillstånd i form av värmebelastning, tryck, temperatur och flöden. Ett antal olika alternativ har studerats och modifierats för att bästa möjliga kanalutformningen. Resultaten visar att för en två-pass rektangulär kanal (både släta och ribbade), minskar tryckfallet när inloppskanalens geometri reducerades. För en slät kanal påverkar inte den minskade bredden på inloppskanalen värmeöverförning i inlopps- och utloppskanalerna. Vid ribbade kanaler minskar värmeöverföring vid toppen och på toppväggen med minskad bredd på inloppskanalen. Av de olika turbulensmodeller som används för att validera numeriska resultat mot experimentella för fallet med trapetsformad kanal visade sig låg-Re k-epsilon modellen den mest lämpliga. Genom att använda den turbulensmodell som är närmast experimentella data visar det att geometrin med förskjutna ribbor på bakkantsväggen har maximal termiska prestanda. Resultaten från det sammansatta värmeöverföringsproblemet framhåller användning av ånga som kylmedium om den finns tillgänglig eftersom den kräver mindre massflöde för att få samma värden på väggtemperaturerna jämfört med luft vid samma termiska tillstånd. Det kunde också visas att förskjutna turbulensribbor är det bästa alternativet jämfört med andra för att öka värmeöverföringen i bakkanten av ett gasturbinblad med acceptabelt tryckfall i kylkanalen.
QC 20111108
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Haugen, Christina G. M. "Numerical Investigation of Thermal Performance for Rotating High Aspect Ratio Serpentine Passages." The Ohio State University, 2014. http://rave.ohiolink.edu/etdc/view?acc_num=osu1412698677.
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Wiswell, Nicholas A. "Design and Fabrication of Electrostatically Actuated Serpentine-Hinged Nickel-Phosphorous Micromirror Devices." DigitalCommons@CalPoly, 2014. https://digitalcommons.calpoly.edu/theses/1188.
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A process for micromachining of micro-mirror devices from silicon-on-insulator wafers was proposed and implemented. Test methods and force applicators for these devices were developed. Following successful fabrication of these devices, a novel process for fabrication of devices out of the plane of the silicon wafer was proposed, so that the devices could be actuated electrostatically. In particular, the process makes use of thick photoresist layers as a sacrificial mold into which an amorphous nickel-phosphorous alloy may be deposited. Ideal design of the electrostatically actuated micro-mirrors was investigated, and a final design was selected and modeled using FEA software, which found that serpentine-hinged devices require approximately 33% of the actuation force of their straight-beamed counterparts. An aqueous electroless plating solution composed of nickel acetate, sodium hypophosphite, citric acid, ammonium acetate, and Triton X-100 in was developed for use with the process, and bath operating parameters of 85°C and 4.5 pH were determined. However, this electroless solution failed to deposit in the presence of the photoresist. Several mechanisms proposed for deposition failure included leaching of organic solvents from the photoresist, oxidation of the nickel-titanium seed layer on which the deposition was intended to occur, and nonlinear diffusion of dissolved oxygen in the solution.
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Bani, Aïda. "Phytoextraction du Ni dans les sols ultramafiques d'Albanie." Thesis, Vandoeuvre-les-Nancy, INPL, 2009. http://www.theses.fr/2009INPL042N/document.
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Phytoextraction du nickel dans les sols ultramafiques d’Albanie La phytoextraction minière est un procédé de récupération des métaux des sols minéralisés naturels ou pollués à l’aide de plantes hyperaccumulatrices. Elle est une alternative à l’agriculture vivrière des zones ultramafiques. L’objectif de la thèse est le développement d’une technologie de phytoextraction extensive du Ni avec Alyssum murale sur les Vertisols ultramafiques. Pour cela, il s’agissait : i) d’identifier les plantes hyperaccumulatrices les plus efficaces dans le prélèvement du Ni et comprendre les relations entre le prélèvement du métal et sa biodisponibilité, ii) de déterminer les types de sols adaptés à la phytoextraction du Ni et iii) de définir et optimiser un itinéraire agronomique adapté pour l’espèce retenue et pour les conditions édaphiques. Dans ce but, des prospections géobotaniques ont été conduites en Albanie et en Grèce. Puis une étude in situ des facteurs qui influencent la biodisponibilité du Ni et le comportement des plantes sur une toposéquence ultramafique a été mise en place. Enfin un essai agronomique de quatre années sur un site ultramafique d’Albanie (Pojske) a permis de tester la fertilisation, le contrôle des adventices par herbicide et la date de récolte pour optimiser le rendement d’extraction du Ni. Les résultats montrent que parmi l’ensemble des espèces présentes naturellement sur les serpentines des Balkans, A. markgrafii et A. murale ont le plus fort taux d’accumulation du Ni. Les Vertisols ultramafiques présentent une disponibilité élevée du Ni favorable à la phytoextraction minière. La biomasse d’A murale est augmentée de 0,2 t ha-1 à 6,0 t ha-1 à partir des traitements agronomiques et le rendement de phytoextraction de Ni par A. murale est de 23 à 69 kg ha-1. Alyssum murale peut être envisagée comme une culture pérenne et la fertilisation permet d’augmenter la compétitivité de la plante sans affecter les concentrations de Ni dans les parties récoltéesPhytomining is a process for recovering metals with hyperaccumulating plants from natural or polluted soils. It is an alternative to conventional farming in ultramafic areas. The aim of the thesis is the development of an extensive phytoextraction technology with Alyssum murale on ultramafic Vertisols. Therefore, work was conducted to i) identify the most effective Ni hyperaccumulators, and understand the relationship between metal uptake and bioavailability, ii) identify soil types suitable for phytoextraction, and iii) define and optimize agronomic practices adapted to the plant species and the edaphic conditions. Hence, geobotanical surveys were conducted in Albania and Greece. Then an in situ study was run on an ultramafic toposequence to assess the factors that influence Ni bioavailability and behavior of plants. Finally a four-year field trial was carried out on an ultramafic site in Albania (Pojske) where fertilization, weed control by herbicide, and harvest date were tested to optimize the efficiency of Ni extraction. The results showed that A. markgrafii and A. murale exhibit the highest rate of Ni accumulation among all species of Balkan serpentines. The ultramafic Vertisols have a high Ni availability phytoextraction and are favourable for phytomining. A. murale biomass increased from 0.2 t ha-1 to 6.0 t ha-1 due to optimization of agronomic treatments, and performance of phytoextraction from 23 to 69 kg ha-1. Alyssum murale can be seen as a perennial crop, and fertilization increases the competitiveness of the plant without affecting the Ni concentrations in the harvested parts
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Goldman, Gabriel Jacob. "Design Space and Motion Development for a Pole Climbing Serpentine Robot Featuring Actuated Universal Joints." Thesis, Virginia Tech, 2009. http://hdl.handle.net/10919/31560.
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Each year, falls from elevated structures, like scaffolding, kill or seriously injure over a thousand construction workers (Bureau of Labor Statistics, 2007). To prevent such falls, the development of a robotic system is proposed that can climb and navigate on the complex structures, performing hazardous inspection and maintenance in place of humans. In this work, a serpentine robotic system is developed that will be able to climb pole-like structures, such as scaffolding and trusses, commonly found on work sites. Serpentine robots have been proven to be effective at traversing unstructured terrains and manipulating complex objects. The work presented in this thesis adds a new method of mobility for serpentine robots, specifically those with actuated universal joint structures. Movement is produced by inducing a wobbling motion between adjacent modules through oscillatory motions in the actuated axis of the universal joint. Through the frictional interactions between the modules of the serpentine and the surface of the pole, the wobbling motion lets the serpentine effectively roll up the poleâ s surface.
This work investigates theoretical and experimental results for a serpentine robot climbing a pole structure. It discusses the structure and design parameters of the robot and develops relationships between them. These geometric and performance-based relationships are then used to create a design space that provides a guide for choosing a combination of module dimensions for a desired set of performance parameters. From this, case studies are shown which give examples of how the design space can be used for several different applications.
Based on the design space procedure, a serpentine robot, HyDRAS (Hyper-Redundant Discrete Robotic Articulated Serpentine) was designed and built. The robot was used to prove the validity of the design space procedure and to validate the climbing motion algorithms. Several tests were performed with HyDRAS that showed the practicality of the helical rolling motion, as well as the feasibility of serpentine pole climbing. Observations and discussion based on the experiments are given, along with the plans for future work involving pole-climbing serpentine robots.Master of Science
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Berdouzi, El Houssaine. "Etude de la dispersion des polluants minéraux autour de la mine de Bou-Azzer (Anti - Atlans Central, Maroc)." Vandoeuvre-les-Nancy, INPL, 1999. http://www.theses.fr/1999INPL088N.
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Sundin, Greger. "For Princes or Maids? : Provenance, form and value of serpentine at Skokloster castle." Thesis, Stockholms universitet, Konstvetenskapliga institutionen, 2010. http://urn.kb.se/resolve?urn=urn:nbn:se:su:diva-52492.
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Skokloster castle, Sweden, houses a group of more than fifty objects in serpentine stone, acquired during the 17th century. The group is generally called Wrangels fältservis [Wrangel’s field service], referring to field marshall Carl Gustaf Wrangel (1613-1676). The, in many aspects, unresearched material is here approached through the field of material culture studies. The thesis is based on a three-partite approach towards the material, in which the first is the result of actual handling and examination of the objects, paired with a comparative analysis of similar objects regarding dating and influences. The second is a theoretical study of form and serpentine matter, and why the serpentine objects share so many form elements with metal artifacts. The third is based on inventory research and aspects of value, both monetary and cultural. The ascribed value of the group varied over time, from being used as kitchen utensils in the 17th and 18th century, to be regarded as private museum pieces in the 19th and 20th century. The various attitudes have left marks on the objects, both physical (as in level of attention given to repairs etc.) and in inventory matter (as in location and descriptive detail), which can be studied and reveal information otherwise unaccessible.
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Angeloudis, Athanasios. "Numerical and experimental modelling of flow and kinetic processes in serpentine disinfection tanks." Thesis, Cardiff University, 2014. http://orca.cf.ac.uk/58914/.
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New water directives impose strict regulations to reduce the footprint of treatment operations and contaminant levels, which suggest a performance review of water treatment facilities, including disinfection contact tanks. Serpentine contact tank units suggest plug flow to be the optimal hydrodynamic condition at which disinfection performance is maximized. However, previous studies indicate that flow exhibits a residence time distribution (RTD) which can be significantly distorted from what is dictated by plug flow. Over the years, there has been rising concern over the impact of such digressions from optimal hydraulic conditions on microbe inactivation and the regulation of potentially carcinogenic Disinfection By-Products (DBPs). With the growth of computing power and the advancement of computational models, the potential of contact tank water disinfection optimization by means of numerical modelling techniques can be assessed. In this study, Acoustic Doppler Velocity (ADV) and fluorescent tracer dye measurement campaigns are carried out to assess the hydraulic efficiency of a serpentine contact tank physical model and evaluating appropriate indicators. Then, three-dimensional Computational Fluid Dynamics (CFD) models are set up to simulate the hydrodynamic and solute transport processes for a variety of contact tank geometries examining the effects of inlet design, baffling configuration and tank scale. The simulation capability to reproduce the actual conditions is attested through comparisons against available laboratory results. The CFD approach is subsequently refined with appropriately selected kinetic models, describing the processes of disinfectant decay, pathogen inactivation and DBP formation. Results highlight that computational models can become invaluable tools for the simulation of disinfection processes as they can reproduce the conditions encountered experimentally to a satisfactory extent. Moreover, the optimization of hydraulic efficiency, as studied numerically, facilitates more uniform disinfectant contact time which corresponds to greater levels of pathogen inactivation and a more controlled by-product accumulation.
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Sambatti, Julianno Bergoch Monteiro. "Evolutionary ecology and demographic population genetics of the Californian serpentine sunflower, Helianthus exilis /." For electronic version search Digital dissertations database. Restricted to UC campuses. Access is free to UC campus dissertations, 2004. http://uclibs.org/PID/11984.
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Lin, Jin-lang, and 林錦郎. "Study of Mechanical Quarrying of Serpentine." Thesis, 1998. http://ndltd.ncl.edu.tw/handle/68241859323503979615.
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Zheng, Kai-Jue, and 鄭凱覺. "Study of serpentine interconnect for signal integrity." Thesis, 2017. http://ndltd.ncl.edu.tw/handle/cv8q77.
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碩士國立雲林科技大學
電機工程系
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With the increase of data rate, wiring constraints for digital circuits are more and more stringent. Previous wiring methods may no longer be suitable for today’s high-speed digital circuits. In high-speed digital circuits, serpentine lines have been widely adopted for time-delay and synchronization purposes. Hence, we aim in this thesis to provide guidelines for wiring using serpentine lines in some scenarios, hoping that these guidelines may benefit the industrial development in Taiwan. From time-domain reflectometer signals, we can observe the “macro” characteristic impedance variation along a serpentine line. Various parametric studies were conducted in this thesis to see how the characteristic impedance fluctuates along the line. Using DDR4, PCIe, and SATA as three transmission-interface examples, we further studied how eye diagrams and their associated eye metrics are affected by serpentine lines of various parameters. Sometimes, the physical space is not large enough to allow further adjustment of the serpentine line. One may resort to via-holes or different substrate materials, which may be regarded as cumbersome or impractical in terms of fabrication cost. As a remedy, we proposed three compensation methods to lessen the fluctuation of the characteristic impedance along a serpentine line, without changing the layer stacking and without consuming more circuit layout area.
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Gonçalves, Susana Cláudia de Freitas Rodrigues. "Nickel tolerance in Cenococcum geophilum from serpentine soils : an adaptive trait : living in serpentine : the tale of a hidden fungus." Doctoral thesis, 2008. http://hdl.handle.net/10316/3742.
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