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1
Symeou, Vasilis. "Transition from compression to strike-slip tectonic styles along the northern margin of the Levant Basin." Thesis, Sorbonne université, 2018. http://www.theses.fr/2018SORUS003/document.
Full textAbstract:
En Méditerranée orientale, l’arc de Chypre est une frontière géologique majeure où interagissent les plaques Arabie, Afrique, Eurasie et la microplaque anatolienne. Il constitue la limite Nord du bassin du Levant (croûte continentale amincie étirée) et du bassin d’Hérodote (croûte océanique). L’arc de Chypre est directement lié à la convergence vers le Nord de la plaque Africaine sur la plaque Eurasienne depuis la fin du Crétacé. Dans la région Egéenne, l’indentation de la plaque Arabique sur la partie orientale de la plaque Anatolienne d’une part, et l’effet « roll back » du plan de subduction africain dans la partie occidentale de la plaque Anatolienne d’autre part, ont pour conséquence l’expulsion de l’Anatolie depuis la fin du Miocène à aujourd’hui, ce qui se traduit par un décrochement le long de l’arc de Chypre, se prolongeant sur l’île de Chypre. Plusieurs questions scientifiques concernant le cadre géologique de la région ont été étudiées au cours de ce projet. Comment la déformation est-elle intégrée dans le système de l'Arc de Chypre ? La variation crustale de chaque domaine affecte-t-elle le style de déformation ? Comment cette déformation est-elle enregistrée dans les sédiments de l’île de Chypre ? Comment ces déformations (Onshore / Offshore) peuvent être connectées au contexte géodynamique régional ? Afin de répondre à ces questions scientifiques, des données sismiques de réflexion 2D ont été utilisées, et ont permis d’imager les structures principales et leur évolution spatiale dans les parties Sud et Orientale de Chypre. L'interprétation de ces données conduit à l'identification de neuf unités tectono-sédimentaires dans trois différents domaines de la croûte crustale au sud du système de l'Arc chypriote: (1) le bassin du Levant (croûte continentale amincie), (2) le micro-continent d'Eratosthène (croûte continentale) et (3) le bassin d'Hérodote (croûte océanique). Dans ces domaines, de nombreuses structures tectoniques ont été documentées et analysées afin de comprendre le mécanisme et le timing de la déformation. À la limite nord du domaine du bassin du Levant, des accidents majeures chevauchants vers le Sud ont été documentés dans le bassin de Chypre, commençant au début du Miocène et enregistrés par les failles de Larnaca et de Margat. La faille Latakia n’a quant à elle enregistré aucune activité pendant cette période. L'apogée de la déformation s'est produite du Miocène moyen jusqu’à la fin du Miocene, l'activité de la faille de Latakia indiquant la propagation vers le Sud du front de déformation. Cette migration vers le sud a été documentée à partir du développement de bassins flexuraux et des chevauchements stratigraphiques dans le bassin de Chypre. Les pulses tectoniques successifs depuis la fin du Miocène jusqu’à aujourd’hui, sont indiquées par les discordances angulaires et les bassins piggy back. Pendant la période Plio-Pléistocène, l’expulsion vers l'ouest de la microplaque anatolienne a entraîné la réactivation des structures existantes. L'évolution de la déformation le long de la limite de la plaque est identifiée à partir de la création de structures en fleur positives révélant des mouvements transpressifs le long des failles Larnaca et Latakia (domaines orientaux). Le domaine central comprend le mont sous-marin d'Eratosthène qui se caractérise comme une plate-forme carbonatée mésozoïque recouverte d'une mince séquence sédimentaire allant des dépôts Messinien aux dépôts Pléistocène<br>The Cyprus Arc system is major plate boundary of the Eastern Mediterranean where different plates interact, namely Arabia, Africa, Eurasia, as well as the Anatolian micro-plate. It constitutes the northern boundary of the Levant Basin (of thin stretched continental crust) and the Herodotus Basin (of oceanic crust). The Cyprus Arc is directly linked with the northward convergence of the African continental plate with respect to the Eurasian continental plate since Late Cretaceous time. The indentation of the Arabian plate and the slab pull effect of the African plate roll back in the Aegean region on the eastern and western part of the Anatolian plate respectively, leads to the westward escape of Anatolia from Late Miocene to Recent, which results in a strike-slip component along the Cyprus Arc system and onshore Cyprus. Several scientific questions with regard to the geological setting of the region were investigated during this project. How is the deformation accommodated at the Cyprus Arc system? Is this deformation style affected by the variation of the crustal nature at each domain? How is this deformation recorded on the sedimentary pile onshore Cyprus? How does the onshore and offshore deformation connect within the geodynamic context of the region? In order to answer these scientific questions, 2D reflection seismic data were utilized, that image the main plate structures and their lateral evolution south and east of Cyprus. Interpretation of these data lead to the identification of nine tectono-sedimentary packages in three different crustal domains south of the Cyprus Arc system: (1) The Levant Basin (attenuated continental crust), (2) The Eratosthenes micro-continent (continental crust) and (3) The Herodotus Basin (oceanic crust). Within these domains, numerous tectonic structures were documented and analysed in order to understand the mechanism and timing of deformation. At the northern boundary of the Levant Basin domain, thrust faults verging towards the south were documented in the Cyprus Basin with the thrust movement commencing in Early Miocene time as indicated by on the Larnaca and Margat Ridges. On the Latakia Ridge no activity was identified during this time interval. The acme of deformation occurred in Middle to Late Miocene time, with the activity of the Latakia Ridge indicating the forward propagation of the deformation front towards the south. This southward migration was documented from the development of flexural basins and from stratigraphic onlaps in the Cyprus Basin. Successive tectonic pulses through the Late Miocene until Recent times, are indicated from the angular unconformities and the piggy back basins. In Plio-Pleistocene time, the westward escape of the Anatolian micro-plate resulted in the reactivation of existing structures. The evolution of deformation along the plate boundary is identified from the creation of positive flower structures revealing transpressive movements along the Larnaca and Latakia Ridges (eastern domains). The central domain includes the Eratosthenes Seamount which is characterized as a Mesozoic carbonate platform covered by a thin sequence of sediments ranging from Miocene-Messinian to Pliocene-Pleistocene depositions
2
Symeou, Vasilis. "Transition from compression to strike-slip tectonic styles along the northern margin of the Levant Basin." Electronic Thesis or Diss., Sorbonne université, 2018. http://www.theses.fr/2018SORUS003.
Full textAbstract:
En Méditerranée orientale, l’arc de Chypre est une frontière géologique majeure où interagissent les plaques Arabie, Afrique, Eurasie et la microplaque anatolienne. Il constitue la limite Nord du bassin du Levant (croûte continentale amincie étirée) et du bassin d’Hérodote (croûte océanique). L’arc de Chypre est directement lié à la convergence vers le Nord de la plaque Africaine sur la plaque Eurasienne depuis la fin du Crétacé. Dans la région Egéenne, l’indentation de la plaque Arabique sur la partie orientale de la plaque Anatolienne d’une part, et l’effet « roll back » du plan de subduction africain dans la partie occidentale de la plaque Anatolienne d’autre part, ont pour conséquence l’expulsion de l’Anatolie depuis la fin du Miocène à aujourd’hui, ce qui se traduit par un décrochement le long de l’arc de Chypre, se prolongeant sur l’île de Chypre. Plusieurs questions scientifiques concernant le cadre géologique de la région ont été étudiées au cours de ce projet. Comment la déformation est-elle intégrée dans le système de l'Arc de Chypre ? La variation crustale de chaque domaine affecte-t-elle le style de déformation ? Comment cette déformation est-elle enregistrée dans les sédiments de l’île de Chypre ? Comment ces déformations (Onshore / Offshore) peuvent être connectées au contexte géodynamique régional ? Afin de répondre à ces questions scientifiques, des données sismiques de réflexion 2D ont été utilisées, et ont permis d’imager les structures principales et leur évolution spatiale dans les parties Sud et Orientale de Chypre. L'interprétation de ces données conduit à l'identification de neuf unités tectono-sédimentaires dans trois différents domaines de la croûte crustale au sud du système de l'Arc chypriote: (1) le bassin du Levant (croûte continentale amincie), (2) le micro-continent d'Eratosthène (croûte continentale) et (3) le bassin d'Hérodote (croûte océanique). Dans ces domaines, de nombreuses structures tectoniques ont été documentées et analysées afin de comprendre le mécanisme et le timing de la déformation. À la limite nord du domaine du bassin du Levant, des accidents majeures chevauchants vers le Sud ont été documentés dans le bassin de Chypre, commençant au début du Miocène et enregistrés par les failles de Larnaca et de Margat. La faille Latakia n’a quant à elle enregistré aucune activité pendant cette période. L'apogée de la déformation s'est produite du Miocène moyen jusqu’à la fin du Miocene, l'activité de la faille de Latakia indiquant la propagation vers le Sud du front de déformation. Cette migration vers le sud a été documentée à partir du développement de bassins flexuraux et des chevauchements stratigraphiques dans le bassin de Chypre. Les pulses tectoniques successifs depuis la fin du Miocène jusqu’à aujourd’hui, sont indiquées par les discordances angulaires et les bassins piggy back. Pendant la période Plio-Pléistocène, l’expulsion vers l'ouest de la microplaque anatolienne a entraîné la réactivation des structures existantes. L'évolution de la déformation le long de la limite de la plaque est identifiée à partir de la création de structures en fleur positives révélant des mouvements transpressifs le long des failles Larnaca et Latakia (domaines orientaux). Le domaine central comprend le mont sous-marin d'Eratosthène qui se caractérise comme une plate-forme carbonatée mésozoïque recouverte d'une mince séquence sédimentaire allant des dépôts Messinien aux dépôts Pléistocène<br>The Cyprus Arc system is major plate boundary of the Eastern Mediterranean where different plates interact, namely Arabia, Africa, Eurasia, as well as the Anatolian micro-plate. It constitutes the northern boundary of the Levant Basin (of thin stretched continental crust) and the Herodotus Basin (of oceanic crust). The Cyprus Arc is directly linked with the northward convergence of the African continental plate with respect to the Eurasian continental plate since Late Cretaceous time. The indentation of the Arabian plate and the slab pull effect of the African plate roll back in the Aegean region on the eastern and western part of the Anatolian plate respectively, leads to the westward escape of Anatolia from Late Miocene to Recent, which results in a strike-slip component along the Cyprus Arc system and onshore Cyprus. Several scientific questions with regard to the geological setting of the region were investigated during this project. How is the deformation accommodated at the Cyprus Arc system? Is this deformation style affected by the variation of the crustal nature at each domain? How is this deformation recorded on the sedimentary pile onshore Cyprus? How does the onshore and offshore deformation connect within the geodynamic context of the region? In order to answer these scientific questions, 2D reflection seismic data were utilized, that image the main plate structures and their lateral evolution south and east of Cyprus. Interpretation of these data lead to the identification of nine tectono-sedimentary packages in three different crustal domains south of the Cyprus Arc system: (1) The Levant Basin (attenuated continental crust), (2) The Eratosthenes micro-continent (continental crust) and (3) The Herodotus Basin (oceanic crust). Within these domains, numerous tectonic structures were documented and analysed in order to understand the mechanism and timing of deformation. At the northern boundary of the Levant Basin domain, thrust faults verging towards the south were documented in the Cyprus Basin with the thrust movement commencing in Early Miocene time as indicated by on the Larnaca and Margat Ridges. On the Latakia Ridge no activity was identified during this time interval. The acme of deformation occurred in Middle to Late Miocene time, with the activity of the Latakia Ridge indicating the forward propagation of the deformation front towards the south. This southward migration was documented from the development of flexural basins and from stratigraphic onlaps in the Cyprus Basin. Successive tectonic pulses through the Late Miocene until Recent times, are indicated from the angular unconformities and the piggy back basins. In Plio-Pleistocene time, the westward escape of the Anatolian micro-plate resulted in the reactivation of existing structures. The evolution of deformation along the plate boundary is identified from the creation of positive flower structures revealing transpressive movements along the Larnaca and Latakia Ridges (eastern domains). The central domain includes the Eratosthenes Seamount which is characterized as a Mesozoic carbonate platform covered by a thin sequence of sediments ranging from Miocene-Messinian to Pliocene-Pleistocene depositions
3
Epaminonda, Epaminondas. "Institutional change and business system diversity : continuities and contradictions in postcolonial Cyprus." Thesis, University of Manchester, 2009. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.632846.
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This thesis analyses institutions and business system characteristics in Cyprus with the aim of describing economic organisation patterns in the country and discussing issues of institutional change and business system diversity. More specifically, by reviewing the development and current features of the legal, financial and education systems, industrial relations and authority relations, the extent and kind of British colonial influence on each institution is examined and the ways in which transformed institutions shape ownership and control of firms, relations between them and employment practices are explored. Research findings are expected to contribute to existing empirical knowledge regarding the different ways of organising and controlling economic activities by describing arrangements in a postcolonial society and inform theoretical analyses of processes of institutional change and the impact of colonial rule on economic organisation. Results indicate that the colonial experience transformed completely institutions like the legal system and greatly influenced aspects of the development of others, such as the education and financial systems, authority relations and industrial relations. These institutional changes contributed, first, to the creation of a significantly different institutional environment compared to neighbouring countries that were not colonised by a major European power and, second, led to considerable heterogeneity in some if its aspects. This institutional environment offered more potential for business system diversity and two major groups of firms may be identified with distinct business system characteristics in Cyprus, private firms and banks. The former group consists of firms that are largely family owned and controlled, are characterised by authority relations that are more paternalistic and exhibit employment practices that are more informal whereas in banks, ownership is largely market based, control more decentralised, relations with other firms more adversarial, authority relations less paternalistic and employment practices more formal. The empirical analysis suggests a number of theoretical points regarding colonialism, institutional change and business system diversity. First, it highlights that the three key mechanisms driving institutional change - the coercive, the mimetic and the normative - can be identified as contributing to institutional conversion during colonial rule. Coercive mechanisms may include the introduction of a new government administration system whereas mimetic processes, such as copying some of the colonial power's systems, and normative pressures due to the interaction between colonial power and colony were also common. Second, it shows that both radical and evolutionary change of institutions take place. The introduction of a new legal system is an example of abrupt change whereas the influence on the education system, and indirectly on people's values, is more incremental. Third, it suggests that the kind, extent and the rate of institutional conversion depends on the nature of each institution but also on power dynamics and preferences of individual and collective actors in both the exporter and receiving country. These observations highlight, fourth, the role of institutional entrepreneurs who influence institutional development by reflecting on structures, using their analytical and political skills and mobilizing others. Finally, these multiple influences on institutions are likely to result in considerable diversity within them, something that gives firms more 'social and economic space' from which to choose and formulate their own distinctive business system characteristics.
4
Payne, Anne Sheila. "The structural and sedimentary evolution of the Polis Graben System, West Cyprus." Thesis, University of Edinburgh, 1995. http://hdl.handle.net/1842/15605.
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The Polis graben system in west Cyprus consists of two neotectonic extensional basins. The Polis graben is of Late Miocene age, bounded to both sides by major NNW-SSE trending normal faults. Around 7% extension occurred perpendicular to the fault trend. The Pegia half-graben, to the west of the Polis graben, is of latest Pliocene to earliest Pleistocene age and is bounded by WNW-ESE striking normal faults. Approximately 10% extension occurred perpendicular to these faults. In both graben normal faults are seen on three scales; extensional joints are also common. Faults of all scales bound generally internally undeformed fault blocks which are tilted perpendicular to the graben trend, normally back-rotated on synthetic faults and forward rotated on antithetic faults. In the Polis graben, transfer zones accommodate changes in the structural style and timing of faults along the length of the graben. The location of faults within the Polis graben system may be partly controlled by the underlying basement structure. Extensional structures in the Polis gaben are comparable with extensional features in other basins. The sedimentary sequence in west Cyprus reflects the structural development of the two extensional basins. Early to mid-Miocene pre-rift, Late Miocene syn-rift and Pliocene post-rift sequences are recognized in the Polis graben. The first depositional features related to neotectonic structures are seen at the Oligo-Miocene boundary. Erosion of the Palaeogene Lefkara Formation on the margins of the area was followed by deposition of Lower Miocene reef limestones (the Terra Member), whilst basinal chalk deposition (the Miocene Pakhna Formation) continued in the centre of the area. This is thought to reflect relative uplift of west Cyprus and development of a broad basin in the Early Miocene. Hemipelagic carbonates of the Pakhna Formation were deposited throughout the basin by mid-Miocene times. In the Late Miocene, shallowing of the basin occurred and early syn-rift reef limestones of the Koronia Member accumulated on the flanks of a narrow basin. Rapid eustatic fall in the Messinian led to emergence and erosion of the northern part of the graben, and of the area of the Pegia half-graben. The southern basin was the site of syn-rift evaporite deposition (the Kalavasos Formation). In the north, conglomerates and breccias derived from active fault scarps were locally deposited.
5
Erabelli, Prasad Rao 1962. "EXPERT SYSTEM FOR DESIGN OF ARC WELDING (ARTIFICIAL INTELLIGENCE)." Thesis, The University of Arizona, 1987. http://hdl.handle.net/10150/291579.
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Iacovou, Michael. "Interacting levels of conflict : Cyprus, Greek - Turkish relations and the US security system." Thesis, London School of Economics and Political Science (University of London), 1997. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.263645.
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Zhang, Jing. "A crystal window into the crustal arc magma plumbing system." Thesis, Durham University, 2016. http://etheses.dur.ac.uk/11565/.
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Open magmatic processes, including magma mingling, fractionation and assimilation, are responsible for the diversity of magma and crystal compositions common in subduction zone settings. This thesis focuses on investigating pre-eruptive open-system processes using crystal-specific studies. Particularly, we develop calcic amphibole as a robust recorder of magmatic processes. Amphibole is a common mineral phase in water-bearing arc magmas. Its stability is a complex function of temperature, pressure, oxygen fugacity, and melt and volatile compositions. We have developed a new multiple regression analysis of published trace element partitioning data between calcic amphibole and melt. We are able to retrieve statistically significant relationships for REE, Y, Sr, Pb, Ti, Zr and Nb. We also present new pressure-independent and temperature-independent empirical chemometric equations to predict melt major element chemistry from amphibole crystal compositions. This enables us to reconstruct melt chemistry from in situ analyses of amphibole in magmas and plutonic xenoliths. Linking these inverted melt compositions to the observed crystal textures allows us to make robust interpretations of magmatic processes throughout the magma plumbing system. We take the 1951 eruption products of Mt. Lamington volcano as a primary case study. Mt. Lamington is a composite volcano sitting on the Papuan Ultramafic Belt (PUB) ophiolite. The 1951 eruption produced andesitic dome lavas with numerous basaltic-andesitic enclaves and a few PUB ultramafic xenoliths. The mineralogy of the enclaves is dominated by amph+plag, similar to the andesitic lava hosts. The textures of the enclaves vary from fine-grained diktytaxitic to coarser-grained plutonic textured. We interpret this variation to result from variable cooling rates in the enclave-forming magma body when it invades the overlying andesite. The diktytaxitic enclaves contain variable proportions of host-derived amph+plag antecrysts and xenocrysts of ol+sp±cpx±amph with disequilibrium textures, indicating interaction with host lava and assimilation of foreign materials, respectively. A previous study argued that the olivine xenocrysts with chromian spinel inclusions are derived from the PUB, and thus that the PUB contaminated the Mt. Lamington magmas. We demonstrate that this is highly unlikely on the basis of morphological and compositional discrepancies between PUB ol+sp and the xenocrysts. The olivines are considered to represent crystal mush fractionated from precursor(s) of andesitic and/or pre-1951 shoshonitic lavas. Their presence in enclaves represents recycling of earlier-fractionated components through magma recharge. We also revisit and bring new insights on magmatic processes shaping the Ongatiti eruption of Mangakino volcano, amphibole-bearing plutonic nodules exposed in the lavas in Grenada, and the 1991 eruption of Mt. Pinatubo. We demonstrate that reconstructed melt compositions inferred from the rims of amphiboles in pumice clasts of the Ongatiti ignimbrite are in good agreement with the matrix glass compositions. This suggests that equilibrium between the amphibole rims and melts of matrix glass compositions is achieved. The cores of amphiboles from the Ongatiti ignimbrite show large compositional variation as well as disequilibrium textures (e.g. patchy zoning, resorption/dissolution texture), and the predicted melt compositions also display large variations. We interpret that these variations may be due to different degrees of equilibration of the amphiboles derived from crystal mushes with evolved melts over a range of timescales. This interpretation is an alternative to the model provided by an earlier study which instead suggests that source heterogeneity is a major contribution to the crystal chemical diversity in the Ongatiti ignimbrite. For amphiboles in plutonic nodules in Grenada lavas, we are able to predict the melts compositional variations from amphiboles in clinopyroxenite, hornblendite and hornblende gabbro xenoliths, in consistency with melt inclusions hosted in those cumulates. We interpret that the variations may be a result of in situ melt evolution due to extensive crystallization of the cumulate mineral phases, or equilibration of cumulate fragments with later evolved melts. Bimodal amphibole populations and hence inferred melt compositions in Mt. Pinatubo indicate magma mingling process, in consistency with conclusions of earlier studies. The inferred melt trace element compositions from bimodal groups also record co-crystallization of plagioclase, ilmenite, zircon and apatite together with amphiboles to varying extent, and the interpretation can be generally supported by petrography evidences.
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Gaunce, Austin Cody. "PREDICTIVE MODELING OF DC ARC FLASH IN 125 VOLT SYSTEM." UKnowledge, 2019. https://uknowledge.uky.edu/mng_etds/46.
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Arc flash is one of the two primary hazards encountered by workers near electrical equipment. Most applications where arc flash may be encountered are alternating current (AC) electrical systems. However, direct current (DC) electrical systems are becoming increasingly prevalent with industries implementing more renewable energy sources and energy storage devices. Little research has been performed with respect to arc flash hazards posed by DC electrical systems, particularly energy storage devices. Furthermore, current standards for performing arc flash calculations do not provide sufficient guidance when working in DC applications. IEEE 1584-2002 does not provide recommendations for DC electrical systems. NFPA 70E provides recommendations based on conservative theoretical models, which may result in excessive personal protective equipment (PPE). Arc flash calculations seek to quantify incident energy, which quantifies the amount of thermal energy that a worker may be exposed to at some working distance. This thesis assesses arc flash hazards within a substation backup battery system. In addition, empirical data collected via a series of tests utilizing retired station batteries is presented. Lastly, a predictive model for determining incident energy is proposed, based on collected data.
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Mederer, Joachim. "Water Resources and Dynamics of the Troodos Igneous Aquifer-system, Cyprus - Balanced Groundwater Modelling -." Doctoral thesis, kostenfrei, 2009. http://www.opus-bayern.de/uni-wuerzburg/volltexte/2009/3730/.
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Theodosiadou, Elena. "Central curriculum control in the educational system of Cyprus : from theory to teachers' practice." Thesis, London South Bank University, 2008. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.479018.
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Central curriculum provision, regulation and control may be considered as signs of a well administered educational system, but in practice they may lead to the cultivation of unhappy teachers. The centralised mode of management control, as it will be investigated here is a strong way to ensure the state's regulation and monitoring of the schools' pedagogic practice. The research aims to: first, investigate the existence, type and form of the state curriculum provision and control in the educational system of Cyprus at the primary sector; and second, examine the teachers' and administrators' (inspectors') views in relation to the state curriculum provision and control at a theoretical, practical and personal level. Therefore the main research question of the study is: How is central curriculum provision and state curriculum control expressed and experienced by teachers at the primary sector of the educational system in Cyprus? Five hypotheses were formulated to be tested for the purposes of the study: 1. The educational process is subject to central, hierarchical and bureaucratic control and regulation, by the official provider the Ministry of Education and Culture through a system of controlled teacher inspection. 2. In order to explain the operation of state/central curriculum control in the educational system of Cyprus, the focus will have to be on the central curriculum itself and on its three message systems namely the content, the pedagogy and the evaluation, that constitute the process of educational transmission and acquisition. 3. State control is also experienced in the curriculum provision in Cyprus, which is highly centralised and textbook-based. 4. The process of educational acquisition is based more on the competence model of educational provision, rather than on the performance model. 5. There are incompatibilities and inconsistencies within the educational transmission process realised through the three message systems as purported by the official and local recontextualising field, representing the inspectors and the teachers. The research analysis at both the theoretical level, as presented in official documentation, and the practical level, as presented in the form of teachers' and inspectors' responses (with the use of questionnaires and interviews) led us to suggest the following: The primary school teachers in Cyprus experience in their everyday school life, actions of central curriculum control and regulation which can usually lead to frustration, stress and anxiety, while at the same time their autonomy, confidence and professionalism can be badly damaged. The above are mainly caused by the system of controlled teacher inspection, whose role is to ensure obedience and uniformity in the pedagogy offered to pupils, if teachers are to be assessed well, for future professional development and promotion. The existence of this centralised mode of control in the form of the centrally appointed agents over schools and the compulsory use of the single text-book for the implementation of the National Curriculum, influence greatly the competence model of pedagogic practice, in a way that the pattern of state control in the educational system of Cyprus has the inherent potential to invalidate the main principles of the pedagogic model, before that reaches the classroom. As a result, the modalities of the competence model are being transformed and manipulated in the recontextualising process starting from the official to the local level, creating thus a conflict and a battle between the two levels.
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Moura, Francisco José. "Vapour phase synthesis of AIN using a transferred arc plasma system." Thesis, McGill University, 1993. http://digitool.Library.McGill.CA:80/R/?func=dbin-jump-full&object_id=41728.
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This work introduces a new concept for the synthesis of ultrafine aluminum nitride powder. A transferred arc plasma torch of 6.5 kW was used as a heat source to vaporize an aluminum ingot as a source of aluminum vapour for the synthesis of aluminum nitride outside the plasma chamber. The aluminum vapour produced in the plasma chamber was carried by the argon plasma gas to a tubular synthesis reactor where it reacted with ammonia injected radially. The effects of arc current, arc length and argon flow rate on the aluminum evaporation rate and the gas temperature reached in the mixing zone were studied. The results show that long arcs, high currents and high argon flow rates were best to maximize the temperature in the mixing zone and short arcs, high current and high argon flow rate were best for high evaporation rates. Experiments were performed to study the effect of arc length, nitriding agent used, ammonia jet momentum, ammonia flow rate, residence time and temperature on the conversion to aluminum nitride. Conversions up to 100% were achieved. The aluminum nitride produced had an average particle size of approximately 20 nm and specific surface area of about 90 m$ sp2$/g. A numerical model, describing the aerosol particle size evolution, developed by Proulx and Bilodeau was successfully applied to the system.
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Nevzat, A. (Altay). "Nationalism amongst the Turks of Cyprus: the first wave." Doctoral thesis, University of Oulu, 2005. http://urn.fi/urn:isbn:9514277511.
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Abstract
The rise of competing nationalisms in Cyprus first drew world attention in the 1950's, yet the origins of nationalism in Cyprus can clearly be traced to the closing stages of Ottoman rule on the island during the nineteenth century. While the earlier development of nationalism in the Greek Orthodox community of Cyprus is commonly acknowledged, the pre-World War II evolution of nationalism amongst Cyprus' Moslem Turks is consistently overlooked or misrepresented. Contrary to the conventional wisdom, this work contends that Turkish nationalism in Cyprus did not first emerge in the 1950's, but instead grew gradually from the late nineteenth century onwards; that nationalism amongst the island's Turks was first discernible in a 'civic' form founded on Ottomanism which was gradually, though progressively replaced by Turkish ethno-nationalism; and that while both British colonial policies and especially the threat perceived from the rise of Greek nationalism on the island may have helped spur nationalism amongst the Turks, the continued cultural and political interaction with Ottoman, and even non-Ottoman Turks, and later with the Turkish Republic was at least as influential in fostering nationalist sentiments and prompting their expression in political actions. While particular note is made of the often neglected impact of the Young Turk movement in the early twentieth century, this study acknowledges and seeks to elucidate a complex assortment of variegated stimuli that ranged from international developments, such as the recurring crises in the Balkans and President Wilson's speech on the 'Fourteen Points', to the personal attitudes and attributes of British administrators and domestic inter-ethnic relations, and local and international economic trends and developments. Together, it is maintained, these influences had made Turkish nationalism a perceptible phenomenon amongst the Turks of Cyprus by the time of the October Revolt of 1931.
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Bergstedt, Edwin, Johan Földhazy, and Alexander Lundstjälk. "Vibration Analysis on AC Electric Arc Furnace." Thesis, KTH, Materialvetenskap, 2015. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-173354.
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A computerized Fast Fourier Transform system has been used to analyse vibration measurements sampled from a 100-ton electric arc furnace. It has been the hypothesis that patterns in the vibration data would correlate to specific events in the electric arc furnace during the melting process. The theory was that the vibration patterns would be most powerful in multiples of 50 Hz, as the electric arcs operate with a frequency of 50 Hz. It was concluded that the multiples of 50 Hz were dominant. Investigation was made regarding how the amount of scrap affects the amplitude in the vibrations after a defined amount of energy input. It was confirmed that the intensity of the vibrations decreased with increasing mass and basket volume. Another discovery was the M-shaped pattern at the beginning of the melting process. This pattern was statistically analysed. It was found that 71 % of the 41 charges showed an M-shaped correlation. The appearance of this M-shape was analysed regarding power usage, and steel-type. It was concluded that the steel type affected the appearance of the M-shape. The occurrence of flat-bath was also investigated. The theory was that the vibration data would be fairly constant with the occurrence of flat-bath. It was discovered that the vibration data experienced a somewhat constant behaviour towards the end of the melting process in approximately 57 % of the 41 charges. Difficulties were encountered regarding detection of patterns, and correlating them to specific conditions, due to the many parameters that affect the vibration measurements from charge to charge. It was concluded that vibration analysis are unlikely to be used as an absolute way to foresee every event in the electric arc furnace during each charge. But can rather serve as a statistical tool, upon which decisions of how the melting process should be conducted could be based on.
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Kavi, Moses. "Smart protection system for future power system distribution networks with increased distributed energy resources." Thesis, Queensland University of Technology, 2019. https://eprints.qut.edu.au/124628/1/Moses_Kavi_Thesis.pdf.
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This thesis investigates the impact of increased penetration of distributed energy resources (DERs) on the power system distribution network protection system which has been designed on the premise of passive radial network with unidirectional power flow. The investigation involved developing a multistage morphological fault detection and diagnostic tool called the decomposed open-close alternating sequence algorithm using a signal processing technique called mathematical morphology. This investigation culminated in proposing new strategies for; adaptive overcurrent protection in AC radial distribution network with increased DER penetration and high impedance arc-fault detection in AC and DC power distribution networks.
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Abdurrazak, Gokce Yukselen. "The tense, aspect, mood-modality system of the Turkish spoken in Cyprus : a socio-linguistic perspective." Thesis, SOAS, University of London, 2012. http://eprints.soas.ac.uk/14564/.
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This study discusses the tense, aspect and mood-modality system of the Turkish spoken in Cyprus. Initially a theoretical outline of the concepts of tense, aspect and mood-modality in general and that of the Turkic finite system is given followed by that of the historical development of Turkish grammar-writing tradition. Modern Standard Turkish (MST), being the standard form used by the speakers of Turkish in Cyprus, has always been the dominant variety in formal environments and therefore the donor variety in inter-varietical contacts especially since 1974. Accordingly MST has contributed to development of the Cypriot variety immensely and likewise the tense, aspect, mood-modality system of the standard form based on Göksel-Kerslake's classification sets a good example for the Turkish spoken in Cyprus as well. The parent variety of Turkish spoken in Cyprus was Old Anatolian Turkish (OAT), therefore the main source contributing to the formation of the Turkish variety spoken in Cyprus. It is possible to credit OAT for the diversities of the modern Cypriot variety together with the contact induced diversities. However OAT, being a variety of a multicultural region, itself needs to be socio-linguistically tackled. The lack of information on the Turkification process of Anatolia and on the differences between OAT varieties entails complications in establishing the outlines of the formation stage of the Turkish language in Anatolia. Nevertheless example texts in OAT grammatical studies are sufficient to systemize the finite verbal forms of the variety according to Göksel-Kerslake's classification. It is concluded that the finite verbal system of the Turkish spoken in Cyprus is identical with that of MST in some areas whereas it shows great parallelism with that of OAT in other aspects. Additionally the variety accommodates local forms, which are internal developments in some cases and contact induced in other cases.
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Sun, Jidi. "Implementation of 2-Step Intensity Modulated Arc Therapy." Thesis, University of Canterbury. Department of Physics and Astronomy, 2010. http://hdl.handle.net/10092/3844.
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Intensity modulated arc therapy is a novel treatment technique that has shown great potential to be superior to conventional intensity modulated radiotherapy, both in terms of treatment plan quality as well as treatment delivery. Based on previous literature, a simplified technique called two-step intensity modulated arc therapy (2-step IMAT) was implemented into a treatment planning system. In order to automatically generate treatment plans for this technique, a beam portal shaping method was developed to generate beam segments. A sensitivity analysis was carried out on a geometric phantom to determine optimal parameters for the 2-step IMAT implementation for that particular phantom. The segment weights were optimized using the dose-based and dose-volume-based objective functions. The optimal solution search was based on the gradient-descend algorithm. The dose-based objective function was implemented using a so-called lambda-value-dose-based objective function developed in this work in order to increase both speed and flexibility of the optimization. The successful implementation demonstrated the feasibility of automatic 2-step IMAT treatment planning.
A comparison of conventional arc therapy and 2-step IMAT showed improvements in the target dose uniformity by about 50% for both geometric phantom and clinical paraspinal tumor case, whilst also improving the organ sparing. The comparisons between the lambda-value-dose-based and dose-volume-based optimizations showed a speed advantage of the former by a factor of over five in the phantom study.
The current beam portal shaping approach can be improved by optimizing the segment width and including multiple organs-at-risk in the segment generation algorithm. Future work will also include the implementation of a stochastic optimization to minimize the chance of getting trapped in local minima during the segment weight optimization. In summary, the work of this research showed that the automatic 2-step IMAT planning is a viable technique that can result in highly conformal plans while keeping the treatment planning and delivery simple and straightforward.
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Fanara, C. "A Langmuir multi-probe system for the characterization of atmospheric pressure arc plasmas." Thesis, Cranfield University, 2003. http://dspace.lib.cranfield.ac.uk/handle/1826/96.
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The 'high-pressure' atmospheric (TIG) arc plasma is studied by means of a multi-Langmuir probe system. In order to determine the appropriate regime of operation, definitions of the plasma parameters for the description of the argon arc are considered and evaluations are presented. A description of the probe basic techniques is followed by an in-depth discussion of the different regimes of probe operation. The emphasis is put on atmospheric and flowing (arc) regimes. Probe sheath theories are compared and “Nonidealities” like cooling due to plasma-probe motion and probe emission mechanisms are then described. The extensive literature review reveals that the existing probe theories are inappropriate for a use in the TIG arc, because of ‘high’ pressure (atmospheric), broad range of ionization across the arc, flowing conditions, and ultimately, to the uncertainty about onset of Local Thermodynamical Equilibrium. The Langmuir probe system is built to operate in floating and biased conditions. The present work represents the first extensive investigation of electrostatic probes in arcs where the experimental difficulties and the primary observed quantities are presented in great detail. Analysis methodologies are introduced and experimental results are presented towards a unified picture of the resulting arc structure by comparison with data from emission spectroscopy. Results from different measurements are presented and comparison is made with data on TIG arcs present in literature. Probe obtained temperatures are lower than the values obtained from emission spectroscopy and this ‘cooling’ is attributed to electron-ion recombination. However, it is believed that probes can access temperatures regions not attainable by emission spectroscopy. Only axial electric potential and electric field are obtained because of the equipotential-probe requirement. Estimations of the sheath voltage and extension are obtained and a qualitative picture of the ion and electron current densities within the arc is given.
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Taylor, W. A. "Generation of welding procedures for the submerged arc process using expert system techniques." Thesis, Queen's University Belfast, 1987. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.381901.
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Shinohara, Asako. "Continuous and discrete model-based robust controllers with application to an electric arc furnace cooling system." Thesis, Coventry University, 2001. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.369973.
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Rotsides, Christos. "The educational system of Cyprus since 1960, with particular reference to the relationship with the European Union." Thesis, University of Wolverhampton, 2000. http://hdl.handle.net/2436/90237.
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Carvalho, G. C. "An adaptive control system for off-line programming in robotic gas metal arc welding." Thesis, Cranfield University, 1997. http://dspace.lib.cranfield.ac.uk/handle/1826/4597.
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The aim of this work was to develop an integration concept for using off-line programming in robotic gas metal arc welding of thin sheet steel. Off line-welding parameter optimization and on-line monitoring and adaptive control of process stability and torch-to-workpiece relative distance were used to ensure weld consistency. The concept developed included four main aspects: a) the use of a CAD system to design the workpiece; b) the use of a welding off-line programming system to design the welds, generate the welding parameters and to extract geometrical information from the CAD models to generate a robot program; c) the use of a graphical simulation system to simulate the robot movements; and d) the use of monitoring and adaptive control for ensuring that the required weld quality is delivered. The CAD system was chosen to be the basis for the development of the welding off-line programming system. The generation of optimized welding parameters was based on empirical welding models and the robot program generation was based on on-line programming experience. A PC based monitoring and control system was developed to provide on-line position and process control. The position control was carried out by pre-weld adjusting the initial position of the workpiece using a wire touch sensor and on-line adjusting the torch-to-workpiece distance by moving the workpiece based on the information provided by a through-the-arc sensor. The process control was carried out by automatically trimming the welding voltage such that the most stable process could be obtained. The stability of the process was estimated by using previously established monitoring indices. It was assumed that the off-line welding parameter optimization would provide the deposition rate necessary to produce the required weld quality. Successful welding control trials were performed showing the effectiveness of the adaptive control strategy. An off-line programming system has been developed and the programs generated have been tested by simulation. This showed that simulated positioning errors, produced by deliberate wrong path data, were successfully compensated for by the control system developed in this work.
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Abu, Bakar Nooh. "ESWELPD : an expert system for the generation of welding procedure of arc welding processes." Thesis, Loughborough University, 1990. https://dspace.lboro.ac.uk/2134/33209.
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The research is focused on the development of an expert system to generate welding procedures for arc welding processes. The system has been developed on an IBM AT microcomputer, using an expert system shell KES (Knowledge Engineering System), a product of Software Architecture & Engineering Inc. The system is primarily intended for novice users, hence good 'help' facilities and graphical representations are provided in the system.
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Mukti, Muhammad Ma'ruf. "Tectonic Evolution of the South Sumatra-Java Forearc System from Deep Seismic Reflection Data." Paris, Institut de physique du globe, 2013. http://www.theses.fr/2013GLOB1101.
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Tardani, Daniele. "Metal fluxing in a large-scale intra-arc fault system: insights from the Liquiñe-Ofqui fault system, southern Chile." Tesis, Universidad de Chile, 2017. http://repositorio.uchile.cl/handle/2250/144594.
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Doctor en Ciencias, Mención Geología<br>La combinación de un análisis estructural a escala regional junto con una extensa base de datos de isótopos de helio, nitrógeno y carbono, composición química y composición de metales traza en manifestaciones volcánicas/geotermales en la parte norte y central de la Zona Volcánica Sur de Chile, revela el rol de las fallas y estructuras en la circulación de fluidos y en el transporte de metales. Las variaciones regionales en la razones isotópicas 3He/4He, d13C-CO2 y d15N son consistentes con los datos reportados de 87Sr/86Sr en lavas a lo largo del segmento estudiado, los que están fuertemente controlados por la distribución espacial del Sistema de Falla Liquiñe-Ofqui (LOFS), que corresponde a una falla transcurrente de intra-arco, y del Sistema de Fallas Oblicuas al Arco (ALFS), que consiste en un conjunto de fallas transpresivas de rumbo NO. La terminación norte del LOFS muestra las signaturas de 3He/4He más primitivas, mientras que en las otras partes de la región las signaturas de isótopos de helio son controladas por la mezcla entre el 3He de derivación mantélica y el 4He de origen cortical, por asimilación magmáticas en la fuente de los fluidos o por contaminación cortical durante la tránsito de los fluidos en la corteza. Ha sido compilada una base de datos de elementos traza (metales base, metales preciosos y metaloides), tomando muestras de fumarolas y aguas termales, donde han sido analizados los isótopos de helio, carbono y nitrógeno. Contrastar las concentraciones de elementos traza con las razones de isótopos de helio ha permitido determinar que los contenidos de metales en fluidos hidrotermales son el resultado de un fuerte control estructural que condiciona la partición selectiva de estos elementos. Las concentraciones más altas de metales base (e.g. Cu, Co, Ni, Pd), provenientes de la lixiviación de la roca caja, se han encontrado en manifestaciones controladas por estructuras NO, mientras que a lo largo del LOFS, las altas vías de permeabilidad permiten el rápido ascenso de metales transportados desde el sistema profundo en fase vapor (e.g. As, Sb, Ge).
El sistema geotermal de alta entalpía Tolhuaca (TGS), ubicado en la parte norte del LOFS se estudió en detalle con el fin de evaluar el desacoplamiento entre Cu y As. Para este fin han sido analizadas una serie de muestras de pirita provenientes de un sondaje de 1km de largo para determinar el contenido de metales traza (e.g. Cu, As, Co, Sb, etc.) y los patrones de zonación de dichos metales dentro de los granos de este sulfuro. Se ha logrado detectar zonaciones en la pirita de la zona de alteración argílica somera, donde bordes ricos en Cu (Co) y núcleos deprimidos en As se alternan con bordes deprimidos en Cu (Co) y núcleos ricos en As. Estos datos de microanálisis se contrastaron con datos químicos de inclusiones fluidas en vetas de cuarzo (altas razones Cu/As) y fluidos del pozo geotermal (bajas razones Cu/As), que muestran una clara correspondencia entre las concentraciones relativas de Cu y As en los fluidos hidrotermales y las zonaciones químicas de la pirita. Estas observaciones proporcionan evidencia directa de captura selectiva de los metales en la pirita como resultado de los cambios en la composición del fluido de formación del mineral, debido probablemente a la separación de un fluido de una sola fase en un vapor de baja densidad y una salmuera más densa, capaz de fraccionar Cu y As.
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Snell, Jared James. "Improved modeling and optimal control of an electric arc furnace." Thesis, University of Iowa, 2010. https://ir.uiowa.edu/etd/741.
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This thesis centers around an electric arc furnace (EAF) at a steel mini-mill in Wilton, IA. First, the thesis replicates previous optimization attempts. Next, the modeling is greatly altered to produce a much improved steel-melting model. Then, a new optimal control system is created and used to reduce energy and fuel costs over the melting process. Finally, results are presented. This thesis shows that when the new optimal control is simulated, the system shows significant energy and fuel savings.
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Beresnev, V. M., O. V. Sobol’, Олександр Дмитрович Погребняк, et al. "About Peculiarities of the Influence of the Negative Bias Potential Applied to the Substrate During the Deposition Process on the Structural State and Properties of the Multilayer system MoN-CrN." Thesis, Sumy State University, 2015. http://essuir.sumdu.edu.ua/handle/123456789/42799.
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Applying transition metal nitrides of Mo and Cr, which are characterized by a relatively low heat of formation, as the components of the multilayer coating, the possibilities of elemental and structural engineering of vacuum-arc coatings under the influence of the bias potential Us and the reaction gas pressure PN are revealed. It was found that at a relatively small thickness of the layers of nanometer range, which provides superhard state of the coatings, the supply of Us with the value of above the critical leads to a drop in hardness, which can be explained by mixing of layers at the interphase boundary.
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Hannon, Jeffrey S. "Reconstructing the Generation, Evolution, and Migration of Arc Magmatism using the Whole-rock Geochemistry of Bentonites: A Case Study from the Cretaceous Idaho-Farallon Arc System." University of Cincinnati / OhioLINK, 2020. http://rave.ohiolink.edu/etdc/view?acc_num=ucin1613745220524224.
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Davuluri, Raghava Sai Chaitanya. "Modeling of spallation phenomenon in an arc-jet environment." UKnowledge, 2015. https://uknowledge.uky.edu/me_etds/63.
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Space vehicles, while entering the planetary atmosphere, experience high loads of heat. Ablative materials are commonly used for a thermal protection system, which undergo mass removal mechanisms to counter the heat rates. Spallation is one of the ablative processes, which is characterized by the ejection of solid particles from the material into the flow. Numerical codes that are used in designing the heat shields ignore this phenomenon. Hence, to evaluate the effectiveness of spallation phenomenon, a numerical model is developed to compute the dynamics and chemistry of the particles. The code is one-way coupled to a CFD code that models high enthalpy flow field around a lightweight ablative material. A parametric study is carried out to examine the variations in trajectories with respect to ejection parameters. Numerical results are presented for argon and air flow fields, and their effect on the particle behavior is studied. The spallation code is loosely coupled with the CFD code to evaluate the impact of a particle on the flow field, and a numerical study is conducted.
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Fugate, Earl L. "NONLINEAR SYSTEM MODELING UTILIZING NEURAL NETWORKS: AN APPLICATION TO THE DOUBLE SIDED ARC WELDING PROCESS." Lexington, Ky. : [University of Kentucky Libraries], 2005. http://lib.uky.edu/ETD/ukyelen2005t00307/etd.pdf.
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Thesis (M.S.)--University of Kentucky, 2005.<br>Title from document title page (viewed on November 8, 2005). Document formatted into pages; contains vi, 64 p. : ill. Includes abstract and vita. Includes bibliographical references (p. 61-63).
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Dehlin, Fredrik. "Implementation of an Autonomous Reactivity Control (ARC) system in a small lead-cooled fast reactor." Thesis, KTH, Fysik, 2019. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-254327.
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Bennett, Steven Russell. "Control and Stability of Upper Stage Launch Vehicle With Hybrid Arc-Ignition Attitude Control System." DigitalCommons@USU, 2019. https://digitalcommons.usu.edu/etd/7518.
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The Utah State University Propulsion Research Laboratory (USUPRL) has recently made significant developments in the area of hybrid rocket systems. This type of propulsion system incorporates a solid fuel and a gas or liquid oxidizer. Hybrid rocket systems are known for their inherent safety, reliability, and restart capability. Over the last several years, the USUPRL has successfully built and tested a hybrid rocket system comprising acrylonitrile butadiene styrene (ABS) plastic and gaseous oxygen (GOX). The system was demonstrated to be fully functional during ground, vacuum, and sub-orbital flight testing. Continuing forward, the USUPRL endeavors to extend the capabilities of this hybrid rocket system to in-space propulsion applications, such as an attitude control systems (ACS). This thesis investigates the feasibility of using the USU Green Hybrid Rocket as an ACS for an intermediate-sized launch vehicle. A computer simulation was developed to demonstrate the control and stability of the spacecraft under the influence of the ACS.
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Andreev, A. A., S. N. Grigorev, O. V. Sobol, M. A. Volosova, V. A. Stolbovoy, and V. Ye Filchikov. "Structural-phase and Strained State of Vacuum-ARC Mo-N Coatings." Thesis, Сумський державний університет, 2012. http://essuir.sumdu.edu.ua/handle/123456789/34806.
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The effect of substrate bias on the structural-phase and elastic stress-strained state during the formation
of vacuum-arc deposited nanostructural coatings of the Mo–N system has been studied. An increase
in the bias potential leads to (i) predominant [111] orientation of the growing molybdenum nitride
crystals with a NaCl-type cubic lattice (γ-Mo2N phase) and (ii) the appearance of a second phase with a
body-centered cubic crystal lattice that is characteristic of pure molybdenum. The elastically strained
(stressed) state of the coating is determined not only by the conditions of deposition, but also by the mechanical
properties of a substrate. In order to provide for formation of coatings in a high-elastic-strained
(stressed) state, it is necessary to deposit coatings onto substrates with high elastic modulus, which prevent
metal flow at the interface.
When you are citing the document, use the following link http://essuir.sumdu.edu.ua/handle/123456789/34806
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Narula, Swati. "Design, modeling and implementation of improved power quality switched mode power supplies for arc welding applications." Thesis, IIT Delhi, 2015. http://eprint.iitd.ac.in:80//handle/2074/8183.
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Almulla, Muhannad. "Implementation of an Arc Model for MV Network with Resonance Earthing." Thesis, KTH, Skolan för elektroteknik och datavetenskap (EECS), 2020. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-278499.
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The most common fault type in electric power systems is the line to groundfault. In this type of faults, an electrical arc is usually developed. The thesispresents a mathematical model that describes the behavior of the arc during afault. The arc model has been verified based on real and simulated tests thatwere conducted on a system that has resonant earthing coil.In addition, two studies have been conducted on the same verified system.The first studied was implemented to see the effect of detuning the resonantearthing coil at different levels. It was noted that detuning the coil affected ACand the DC components in the arc faults. Also, the detuning affected the arcextinction.The second study has been looking at the effects of implementing a parallelresistor to the resonant earthing coil. The tests have been conducted usingdifferent set values of the resistor. In some of the studied cases and during thetesting period, the resistor has affected the self-extinguish behavior of the arc.<br>Den vanligaste feltypen i elektriska kraftsystem är fas till jord. I denna typ avfel utvecklas vanligtvis en elektrisk ljusbåge. Examensarbetet presenterar enmatematisk modell som beskriver ljusbågens beteende under ett fel. Bågmodellenhar verifierats baserat på verkliga tester och simuleringar som utfördespå ett system som har resonansjordningsspole.Dessutom har två studier genomförts på samma verifierade system. Denförsta studien genomfördes för att se effekten av avstämning av den resonantajordningspolen på olika nivåer. Det noterades att avstämning av spolen påverkadeACoch DC-komponenterna i ljusbågsfel.Avstämningen påverkade ocksåljusbågens släckning.Den andra studien har tittat på effekterna av att implementera ett parallelltmotstånd till den resonanta jordningsspolen. Testen har utförts med olikainställda värden på motståndet. I några av de studerade fallen och under testperiodenhar motståndet påverkat ljusbågens självsläckande beteende.
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Solaro-Müller, Clara. "Storage conditions and dynamics of magma reservoirs feeding the major pumiceous eruptions of Dominica (Lesser Antilles Arc)." Thesis, Sorbonne Paris Cité, 2017. http://www.theses.fr/2017USPCC006/document.
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Les grandes éruptions explosives (10 to 1000 km3/eruption) ont été l’un des sujets principaux d’étude de la volcanologie moderne car elles représentent des éruptions de grand impact sur la nature et sur les installations humaines sur Terre. Les pétrologues ont démontré que la proportion de cristaux dans les produits de ces éruptions peut être utilisée pour étudier les dynamiques pré-éruptives de la plomberie magmatique et contraindre les échelles de temps des processus magmatiques. Plus précisément, de nombreuses études ont prouvé que ces cristaux peuvent être remobilisés en des temps courts de 10 à 100 ans avant l’éruption, ce qui rend ces systèmes significativement dynamiques. Plusieurs éruptions ignimbritiques d’un volume de l’ordre de la dizaine de km3 ont été reconnues en Dominique (Arc des Petites Antilles). Nous présentons ici, sur la base d’une étude stratigraphique détaillée, une étude pétrologique des ponces de la phase plinienne qui débute les trois éruptions ponceuses majeures de la Dominique : Layou (~51kyrs cal BP), Roseau (~33kyrs cal BP) et Grand Fond (~24kyrs cal BP). En combinant une étude pétrologique des produits naturels et des produits issus des travaux de pétrologie expérimentale, nous proposons un modèle complet des réservoirs à l’origine des trois éruptions. Les magmas sont des dacites à forte teneur en cristaux (~30%), comprenant plagioclases, orthopyroxènes, clinopyroxènes, amphiboles et oxydes. Les expériences d’équilibre de phases sur ces dacites ont permis de contraindre les conditions de stockage à 850°C, 400 MPa (16 km), ~ΔNNO+1 et une teneur en eau pré-éruptive de ~6-8 wt % pour les trois éruptions. Les orthopyroxènes ont été utilisés pour étudier les dynamiques pré-éruptives du système magmatique. Par une analyse systématique (« Crystal system analysis ») de leur zonation nous avons défini différents environnements magmatiques et leur connections. Les échelles de temps des dynamiques pré-éruptives sont calculées par modélisation de l’interdiffusion Fe-Mg dans les orthopyroxènes. Les caractéristiques chimiques et texturales des orthopyroxènes montrent que ~80-85% des cristaux sont non-zonés, tandis que 15-20% présentent une zonation multiple, normale ou inverse, avec prévalence de cette dernière. Les cristaux non zonés représentent l’environnement magmatique principal, alors que les zonés suggèrent une perturbation pré-éruptive du réservoir. Le « crystal system analysis » appliqué à ces derniers suggère la présence de 4 environnements magmatiques (MEs), avec un mouvement principal des cristaux vers des MEs de compositions moins évoluées, lié à la zonation inverse des cristaux. Cependant, la composition des inclusions vitreuses des orthopyroxènes, montre que les différents MEs sont en équilibre avec un verre de même composition. Ces considérations, couplées aux résultats d’équilibres de phases, nous permettent de définir le réservoir comme un environnement fortement cristallisé (~30%), modérément froid (~850°C) et fortement oxydé (~ΔNNO+1) possédant 80-85% de cristaux non-zonés, remobilisé par un réchauffement de 25-30°C produit par l’injection d’un magma plus chaud sous-jacent. La modélisation de l’interdiffusion Fe-Mg dans les orthopyroxènes indique que le réchauffement s’est produit ~10 ans avant chaque éruption. Ce processus crée la zonation inverse retrouvée dans 15-20% des orthopyroxènes et développe un panache thermique interne au réservoir qui est responsable de l’hétérogénéité cristalline retrouvée dans les échantillons<br>Large silicic eruptions (tens to hundreds of km3/eruption) have been a main subject of study for modern volcanology as they represent volcanic events of great impact on environment and human settlement on Earth. Petrologists have demonstrated that the crystal “cargo” of these eruptions can be used to unravel the pre-eruptive dynamic of their magmatic plumbing system and constrain timescales of the related magmatic processes. Specifically, several studies have proved that this “crystal cargo” can be remobilized and brought to eruption in short timescales of decades to centuries, making these systems more dynamic than previously believed.Several ignimbritic eruptions with a volume of the order of ~10 km3 have been recognized in Dominica (Lesser Antilles arc). On the basis of a detailed chronostratigraphy of the deposits, we present an integrated petrological study of the plinian fallout deposit of the latest three ignimbritic eruptions of Layou (~51kyrs cal BP), Roseau (~33kyrs cal BP) and Grand Fond (~24kyrs cal BP). We combine natural and experimental petrology to investigate the prevailing storage conditions within the reservoir that fed each eruption. Whole rocks are all dacites with crystal contents of ~30%, comprising plagioclase (An50-78), orthopyroxene (En47-63), clinopyroxene (Wo44-45), amphibole (Mg# 0.52-0.60) and Fe-Ti oxide (Mag71-75 and Ilm86-87) and rhyolitic residual melt. Pre-eruptive storage conditions of 850 (±5) °C, 400 MPa (16 km depth), ~ΔNNO+1 and melt water content of ~6-8wt% were determined for all studied eruptions through phase equilibria experiments. Orthopyroxenes were used to investigate the architecture and pre-eruptive dynamics of the plumbing system through a crystal system analysis (CSA) combined to a Fe-Mg diffusion modelling. Textural and chemical features of analysed orthopyroxenes prove that for all eruptions ~80-85% of crystals are unzoned while 15-20% present clear normal, reverse and multiple zoning, with reverse zoning being prevalent. Unzoned crystals represent the main magmatic environment (ME) while reverse zoned ones suggest a pre-eruptive perturbation of the reservoir. 4 MEs are evidenced, with a main movement of crystals towards MEs of less evolved composition, linked with the observed reverse zoning. Nevertheless, major element composition of orthopyroxene-hosted melt inclusions shows that all MEs are in equilibrium with the same melt. Combining results on natural and experimental petrology we can define the reservoirs as a highly crystalline (~30%), moderately cold (850°C) and highly oxidized (~ΔNNO+1) environment with 80-85% of unzoned orthopyroxenes, and 15-20% of zoned orthopyroxenes recording a heating process of 25-30°C, possibly produced by an underplating hotter magma that is responsible of the rejuvenation of the reservoir. By modelling the diffusional relaxation of Fe-Mg chemical gradient on zoned orthopyroxenes, we argue that this heating occurs in short timescales of ~10 years prior to each eruption. This heating process develops, over the considered eruptive time, a plume heating geometry able to bring together, on the scale of the hand sample, crystals of different magmatic environments (MEs)
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Aurora-Smith, Amyce. "The simulation and experimental characterisation of the torque converter damper system." Thesis, University of Bath, 2017. https://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.720660.
Full textAbstract:
In recent years, due to a need to reduce emissions, the automotive industry has focused on increasing vehicle efficiency. One of the areas being examined for potential improvement is the automatic transmission; specifically, the torque converter clutch damper. The better the performance of the damper, the more time the torque converter can be kept in the optimum locked position, thus increasing vehicle efficiency. Currently a large number of vehicle manufacturers use transmission technology sourced from external OEMs; due to a lack of available performance data or validated simulations, sometimes vehicle manufacturers are not able to fully understand the behaviour of the damper. If damper performance (or interactions with other components) cannot be fully assessed during the design development phase, key issues may become known too late in the development process. Thus a deeper understanding of the processes of experimentally characterising and simulating torque converter dampers is required. This thesis describes the development of an arc spring torque converter damper simulation, including the gathering of the experimental data required to validate the simulation. The simulation is used to draw conclusions on the impact of excitation signal form on damper behaviour, leading to new knowledge on the signals required to experimentally characterise a damper. In this thesis a methodology for (and implementation of) the characterisation of torque converter dampers is detailed. It was found that existing available technologies (e.g. fired engines, electric dynamometers) were either too inflexible or prohibitively expensive; thus a novel high frequency mechanical pulsation generator was developed. This solution was developed from a 4 cylinder motored diesel engine; the cylinders are filled with compressed air and the crankshaft driven using an electric dynamometer. Simulation and experimental data has confirmed that mean torque can be controlled using the input dynamometer, with the compressed air producing fluctuations of up to 900Nm amplitude. However, it was found that the frequency of the output pulsations varied from a fired engine; this is due to reactions between the pulsation generator and the stiffness and inertias of other components on the rig. A review of the performance of the novel pulsation generation concept against other damper excitation methods was also conducted. It was determined that fired engines and electric motors are more suitable for durability testing; the flexibility of the electric motors and the low running costs of the pulsation generator suit damper performance tests. The second phase of this project was to develop a simulation of a two-stage arc spring turbine damper. This damper consists of three inertias, separated by two spring sets; the outer spring set has 3 individual arc springs, while the inner spring set has 5 nested pairs. The principle of conservation of angular momentum is applied to each of the three inertias in order to calculate their individual accelerations. This method is also applied when calculating the acceleration and movement of the springs; the arc springs are discretised into mass and (massless) spring segments. Two features not previously seen in literature are included in the simulation; hardstops and nested springs. The physical hardstops limit the movement of the spring sets (relative movements of the inertias). In this study, the nested springs were simulated as a pair of parallel springs, rather than as a single stiffer arc spring; this is due to the friction that occurs between the springs (the inner race of the larger spring forms the housing for the inner spring). These two features highlight the need for hardware examination before simulation development; disassembling the hardware also allows the location of hardstops (and other features) to be measured rather than relying on the test data. Once a damper simulation was designed, a methodology for simulation parameterisation was required; parameterisation is the process of improving simulation performance through iterations of estimated parameters. The simulated damper was excited using sampled experimental data; to maximise parameterisation process efficiency, each time a parameter change was made, a set of key test points were selected in order to assess simulation performance change. It is not recommended that single test points be examined individually; parameter changes may improve simulation performance at one test point but have an adverse reaction at another. A clear causal relationship between simulation timestep and accuracy (as well as simulation run time) was found; a link between the number of discretised segments and simulation accuracy (and run time) was also confirmed. It was determined that 8 segments was optimal for the inner springs and 18 outer segments offered the best balance between computing power and simulation time. A variety of methods for analysing damper (and simulation) performance are presented in this thesis; it was found that for the 2.5 bar torque curve experimental data set the simulation performs excellently, with on average less than 5% error. Overall torque error is less than 10% across the tested speed range (900 to 2800rpm), with mean torque differences between simulated and tested order magnitudes of less than 5Nm. It has been determined that hysteresis loops are not an accurate predictor of real-world damper performance; while they can approximate general trends, they do not cover the normal operating condition. In the final phase of this thesis, the validated simulation has been used to investigate excitation signal, areas of poor damper performance and the link between speed and damper stiffness. By subjecting the simulation to a variety of sinusoidal input signals, it was established that if a sinusoidal signal approximates the 3 most dominant frequencies in a real signal, the damper will behave in a representative manner. Additional orders that have lower frequencies than the dominant order will have a greater impact on the attenuation behaviour of the damper; the effect of additional orders on attenuation behaviour is also linked to their magnitude (relative to the dominant order). A methodology for efficient damper mapping is proposed; the key aim is to produce a dataset that will minimise the length of the parameterisation process while capturing key damper behaviours. It was found that the magnitude of the torque oscillations used to excite the damper is linked to parameter adjustment impact, though this relationship is not linear for all parameters; an approximate level of 300Nm should be used for excitation. Parameters such as spring stiffness and plate inertias are more likely to have a substantial impact on damper performance at frequencies below 70Hz; friction tuning factors are impacted more by magnitude changes at frequencies above 150Hz. It has been demonstrated that while speed can have an effect on magnification ratio, this effect is far less significant at mean torques above the knee point and when sinusoidal input magnitude is kept at or above 300Nm. It was concluded that neither engine speed nor precise excitation magnitude must be replicated in order to predict approximate performance. During the investigation into areas of poor damper performance, it was confirmed that the trend of increasing magnification ratio with lower frequencies ( < 30Hz) seen in experimental data continued. Simulation testing above 140Hz revealed that there is not a linear relationship between increased frequency and increased magnification ratio; these areas of magnification ratio spikes are likely due to system resonances. It has been confirmed that while fluctuation magnitude does impact magnification ratio, fluctuation frequency has the most significant (dominant) impact. Finally, the effect of speed on apparent damper stiffness was investigated for both hysteresis loop testing and across a range of outer spring vibration angles; it was confirmed that increasing speed does result in non-homogeneous compression of the springs. It was established that while speed can have an effect on spring stiffness, this effect will vary significantly depending on the movement range (vibration angle) of the spring.<br>The largest increase in spring stiffness with speed is seen when segments of the spring become inactive (cease to move), hence why the effect of speed is more substantial at vibration angle of < 10°. The simulation was used to confirm the theories linking speed and stiffness found in the literature; higher speeds increase frictional forces, slowing damper segments, resulting in reduced movement. The findings of this thesis are relevant to damper simulation and testing engineers; by expanding knowledge of damper behavioural responses to high frequency excitation signals, as well as demonstrating an effective method for producing validated damper simulations, it is hoped that the vehicle design process will be more efficient and damper modifications more effective.
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Godavarthi, Venkata Sridivya. "Determination of Single Pole Breaker Reclose Time and System Performance Using Real Time Simulation." ScholarWorks@UNO, 2017. http://scholarworks.uno.edu/td/2299.
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This thesis investigates single pole reclosing in series capacitor compensated line. An algorithm is developed to determine the optimal dead time required for single pole reclose of circuit breakers and to reduce the randomness of reclosing time. The algorithm considers conditions of system, fault, voltage zero crossing, arc, and IEEE C37.104-2012 standard de-ionization time. This study also addresses difficulties of single pole reclose operation such as over-voltages at the line, secondary arc extinguishing time, dead time, over-voltages across the series capacitor, and negative sequence current. The system performance is evaluated using a set of metrics based on those operation difficulties. Methods used in the industry such as shunt reactor with the neutral reactor, surge arrester, and MOV are modelled and simulated to capture their effect on the operation difficulties. Comparative analysis is made to rank the effectiveness of each element against difficulties in operating single pole reclosing of circuit breakers.
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Panayiotou, Panayiotis Andrea. "Immovable property taxation and the development of an artificial neural network valuation system for residential properties for tax purposes in Cyprus." Thesis, University of South Wales, 1999. https://pure.southwales.ac.uk/en/studentthesis/immovable-property-taxation-and-the-development-of-an-artificial-neural-network-valuation-system-for-residential-properties-for-tax-purposes-in-cyprus(3ec3bd33-0820-4e21-97f0-a3ea0e303a9a).html.
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The last General Valuation in Cyprus, in 1980, took about twelve years to be completed by the Lands and Surveys Department. The comparison method was adopted and no computerised (mass appraisal) method or tool was used to assist the whole process. Although the issue of mass appraisal was raised by Sagric International, who had been invited to Cyprus as consultants, and recently by DataCentralen A/S with the development of a mass appraisal system based on regression analysis, there has been little literature and no research directly undertaken on the problems and the analysis of immovable property taxation in Cyprus and the development of an artificial neural networks valuation system for houses and apartments. The research project approached the issue of property taxation and mass appraisal through an investigation into Cyprus's needs for an up-dated tax base for equitabileness and for an assessment system capable of performing an effective revaluation at a certain date, with minimum acceptable mean error, minimum data and minimum cost. Investigation within Cyprus and world-wide indicated that this research project is a unique study in relation to Cyprus's property taxation and the development of a computer assisted mass appraisal system based on modular artificial neural networks. An empirical study was carried out, including prototyping and testing. The system results satisfy IAAO criteria for mass appraisal techniques, compare favourably with other studies and established a framework upon which future research into computer assisted mass appraisal for taxation purposes can be developed. In conclusion, the project has contributed significantly to the available literature on the immovable property taxation in Cyprus and the development of a computer assisted mass appraisal system for houses and apartments based on modular artificial neural network method. The proposed approach is novel not only in the context of Cyprus but also world-wide.
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Kouroussis, Dionysios. "Design and implementation of a flexible control system for the power supplies of the vortek arc lamp." Thesis, National Library of Canada = Bibliothèque nationale du Canada, 1998. http://www.collectionscanada.ca/obj/s4/f2/dsk1/tape11/PQDD_0004/MQ40940.pdf.
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Chin, Erika Ming Yee. "A four dimensional volumetric modulated arc therapy planning system for stereotactic body radiation therapy in lung cancers." Thesis, University of British Columbia, 2013. http://hdl.handle.net/2429/44048.
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A novel 4D volumetric modulated arc therapy (4D VMAT) planning system is presented where radiation sparing of organs at risk (OARs) is enhanced by exploiting relative target and healthy tissue motion induced by patient respiration. In conventional radiation therapy, a motion encompassing margin is normally added to the clinical target volume (CTV) to ensure the tumour receives the planned treatment dose. For lung tumours which display large displacements due to patient breathing, this results in a substantial increase in dose to the OARs. These wider margins are incompatible with the growing clinical use of stereotactic body radiation therapy (SBRT) in lung cancer treatment. The ablative dose fractions of SBRT are correlated to significantly better survival rates but also increase the risk of serious normal tissue injury.
The 4D VMAT system aims to reduce OAR dose by incorporating 4D CT information on volumetric target and OAR motions directly into the optimization process. The resulting treatment plans have respiratory phase-optimized radiation beam apertures whose deliveries are synchronized to the patient’s respiratory cycle. The performance of the 4D VMAT system was evaluated by comparing against other tumour motion compensation techniques such as 3D VMAT, gated VMAT and tracked VMAT for a range of tumour motions in both phantom simulations and on SBRT eligible patient 4D CT data.
Results showed that 4D VMAT's ability to spare healthy tissue is superior to 3D VMAT and tracked VMAT. 4D VMAT treatment plan quality relative to gated VMAT is similar and in certain cases, depending on the spatial relationship between anatomical structures, it can be superior. Further dose escalation is possible with 4D VMAT and gated VMAT, but 4D VMAT has the advantage of faster treatment times which are only 11-25% longer than 3D VMAT, whereas gated VMAT are 77-148% longer. Lastly, although 4D VMAT is a respiration synchronized technique, preliminary tests showed that treatment plan quality can be robust to some desynchronization delivery errors caused by irregular patient breathing. This thesis concludes with a detailed discussion on the subsequent investigative tasks that must be conducted to bring 4D VMAT nearer to clinical implementation.
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El, Mallah Nadine Hassan. "Dispersion of the carbon nonotubes in a vacuum arc system and synthesis of copper-carbon nanotubes composites." Thesis, McGill University, 2006. http://digitool.Library.McGill.CA:80/R/?func=dbin-jump-full&object_id=99408.
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Electric arcs operating in the thermo-field mode are used in many industrial processes. They are used in electricity transport and distribution, in metal production industry, and in plasma processing applications like in plasma spraying and as the plasma source in physical vapour deposition (PVD) processes. The electric arc-based systems have the common problem of material degradation at the attachment point of the electric arc on the electrode, mainly the cathode surface. The cathode erosion is particularly severe in higher power devices such as plasma torches and circuit breakers. The cathode erodes while producing the ions needed for the electric discharge to occur. Cathode erosion is one big limitation to the use of electric arcs in industry. Carbon nanotubes (CNTs) are 1-D structures with a diameter in the nanoscale range giving them very good field emission properties. These properties make them possible candidates to form metal-CNT composites that can be used as electrodes. The CNTs presence at the electrode surface may help in providing an enhanced electron emission and reduced erosion. The long term objective of this project is to form a new class of electrode materials, namely copper-CNT nanocomposites. One major problem of using these CNTs in composites is their agglomeration and inability to disperse easily. In this project, a pulsed arc discharge system is used to study the capability to ablate, disperse, transport, and deposit the CNTs onto a substrate. The project involves studying the ability to form a nanocomposite made of copper and CNTs from a target and deposition of the copper-CNT mixture on a substrate.
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Zhang, Zhengwen. "Fast response static var generator for improving the power system performance of an electric arc furnace (EAF)." Thesis, Aston University, 2002. http://publications.aston.ac.uk/11836/.
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Cascaded multilevel inverters-based Static Var Generators (SVGs) are FACTS equipment introduced for active and reactive power flow control. They eliminate the need for zigzag transformers and give a fast response. However, with regard to their application for flicker reduction in using Electric Arc Furnace (EAF), the existing multilevel inverter-based SVGs suffer from the following disadvantages. (1) To control the reactive power, an off-line calculation of Modulation Index (MI) is required to adjust the SVG output voltage. This slows down the transient response to the changes of reactive power; and (2) Random active power exchange may cause unbalance to the voltage of the d.c. link (HBI) capacitor when the reactive power control is done by adjusting the power angle d alone. To resolve these problems, a mathematical model of 11-level cascaded SVG, was developed. A new control strategy involving both MI (modulation index) and power angle (d) is proposed. A selected harmonics elimination method (SHEM) is taken for switching pattern calculations. To shorten the response time and simplify the controls system, feed forward neural networks are used for on-line computation of the switching patterns instead of using look-up tables. The proposed controller updates the MI and switching patterns once each line-cycle according to the sampled reactive power Qs. Meanwhile, the remainder reactive power (compensated by the MI) and the reactive power variations during the line-cycle will be continuously compensated by adjusting the power angles, d. The scheme senses both variables MI and d, and takes action through the inverter switching angle, qi. As a result, the proposed SVG is expected to give a faster and more accurate response than present designs allow. In support of the proposal there is a mathematical model for reactive powered distribution and a sensitivity matrix for voltage regulation assessment, MATLAB simulation results are provided to validate the proposed schemes. The performance with non-linear time varying loads is analysed and refers to a general review of flicker, of methods for measuring flickers due to arc furnace and means for mitigation.
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Weng, Ko-Wei, and 翁克偉. "System and Process Correlation in Cathodic Arc Evaporation." Thesis, 2002. http://ndltd.ncl.edu.tw/handle/79222023800694336652.
Full textAbstract:
博士<br>國立中興大學<br>材料工程學研究所<br>90<br>The research purpose was to develop the new process and the novel system configuration that attributed to reduction and promoted the formation of microdroplets, improvement the interface connection strength leaded to the enhancement of adhesion properties and anti-wear performance, and increased the flexibility of coating system, to extend the application of cathodic arc deposition. The combination of the process and the system design in our study can be categorized into four groups, reformation cathodic arc source, cathodic arc activated deposition (CAAD), current-modulating arc source, and the hybrid PVD, which included the filter arc deposition (FAD) source and an metal plasma ion implantation (MPII) source.
Reformation cathodic arc source, which is based on the original type of the multi-arc cathodic source using the extend shield to prevent the droplets ejection with low angle and the gas feeding path locate behind the cathode that will dramatically increase the flexibility and stability of the system and avoid the extinguished of the arc spot. We evaluated chromium carbide coatings synthesized by reformation cathodic arc evaporation for potential applications in forming and molding operations. The results indicated that Cr3C2 outperforms hard chrome plating and CrN coatings in measures of sliding wear resistance and ease of mold release.
Cathodic arc activated deposition (CAAD); Diamond-like carbon (DLC) films were synthesized using the CAAD process. Energetic Cr plasma with intensive ion energy activates the decomposition of C2H2 and deposits an amorphous carbon film containing a mixture of sp2 and sp3 carbon-bond structures, which result in a DLC film of 3824 Hv(25g) microhardness. The Cr metal inclusion and ion bombardment aid in stress release and the increase of film density. The CAAD-synthesized DLC film possesses apparent adhesion strength of 55 N. The pin-on-disk wear test demonstrates an excellent wear performance of 3000-m of wear endurance tested under 10 N at 0.3 m/s.
Current-modulating arc source; conventional cathodic arc evaporation (CAE) suffers from macroparticle contamination and excessive heat load on the substrates, resulting from the energetic ion flux emitted from hot cathode spots. Herein, a low frequency current-modulating controller was used to modulate the arc currents in high-low cycles. The deposition is conducted primarily during the high-current cycles, while a minimum background-current is maintained to sustain the arc discharge. Cathodes can be operated at currents lower than in the continuous CAE process. Macropraticle ejection is reduced substantially due to the effective cathode cooling. The residual stress of CrN coatings is reduced from 3.8 GPa to 3.0 GPa in a current-modulating CAE process. Results of this system design provide a practical and effective way to operate CAE process with reduced substrate temperature, reduced coating roughness, and improved film adhesion.
The Hybrid PVD designs; CrN coatings were deposited using a hybrid PVD technique including the FAD and MPII sources. MPII is a plasma-based ion implantation process based on an accelerated (10-80 keV) vacuum arc metal plasma source with multiple charge states. At the initial coating stage, low dosage of MPII ion flux helps in surface activation and ion mixing. Subsequently, surface treatments of the as-deposited CrN coating with implantation of metal and/or carbon ions result in densification and phase transformation at a near-surface regime. Wear resistance, corrosion resistance, fatigue strength, and mold-releasing mechanism are significantly improved.
In sum, we can adjust system and process design appropriately according to the requisitions and synthesize the optimum coatings.
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Pai, Feng-Yi, and 白峰毅. "Development of Nanofluid Equipment by Plasma Arc System." Thesis, 2009. http://ndltd.ncl.edu.tw/handle/85345658801762569855.
Full textAbstract:
碩士<br>國立臺灣師範大學<br>機電科技研究所<br>98<br>The purpose of experiment is aim to a methods of nanofluid produce system; refer to previous research data and correction. Consist with several stages: prepa- ration, modification, weld, system installation, tested; use “Evaporation synthesi- zed condensation system” to implement graphite/water nanofluid by selected hig- h energy plasma arc that can vaporize any kind of metal as a heating source, coll- ect vaporized nanoparticle into nanofluid collector. To avoid condensed bigger si- ze of particle due to high temperature or cluster, take paramenter in consideration during the period of experiment; such as working current, collector function, tryi- ng to obtain best process minimum and average nanoparticle.
By mean of two stage experiment, base on fixed current used three different type of collector to gain the proper nanoparticle by analyzing of SEM, EDS. Re- sults show the collector is better for particle collect on stage one. In order to des- ign the best collector and reduce fluid temperature from 0℃ to -2℃, within next step of experiment. Accumulate nanoparticle by different working current plasma arc torch pulse. Then stimulate with ultrasonic after that, analyze by SEM, EDS, particle size analyzer to define which process can produce perfect nanoparticle result in 70A.
As a result, working current 70A average particle is 547nm, I.E.P -24.4mV, 80A average particle is 284nm, I.E.P -21.2 mV, process graphite/water nanofluid hea ting resistance test, found that heating resistance reach to -20% under water tem- perature 50℃, paramenter 80A
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Yuxuan, Wu, and 吳宇軒. "system improvement , measurement and analysis of C-band ARC." Thesis, 2005. http://ndltd.ncl.edu.tw/handle/48535643985449799965.
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碩士<br>國立中央大學<br>通訊工程研究所<br>93<br>We have already developed the active radar calibrator in C-band, the successful one can work in radiometric calibration for two satellites (ERS-2 and ENVISAT) now. In order to calibrate the “K” constant precisely, the system gain and delay time of ARC should be considered in this work.
Old active radar calibrator still has some problem and will be investigated in this thesis. Besides, we will revise the structure of ARC system to solve the problem in old one. On the other hand, some devises of ARC are designed including DRO and microstrip antenna of dual-polarization. The DRO replaces the signal generator and the microstrip antenna replaces the horn antenna for decrease the cost of this system.
The two new devises of ARC will be more powerful when operating the ARC to calibrate the satellites.
Moreover, the design of dual-polarization microstrip antenna can be applied in radiometric calibration of alternative and fully polarimetric satellites.
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Pourmousa, Abkenar AmirHossein. "Wire-arc spraying system: Particle production, transport, and deposition." 2007. http://link.library.utoronto.ca/eir/EIRdetail.cfm?Resources__ID=742310&T=F.
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Kao, Chen-Kai, and 高振凱. "An Embedded System Design for Arc-Based Fractal Coding." Thesis, 2011. http://ndltd.ncl.edu.tw/handle/50664459886987342784.
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碩士<br>國立臺灣海洋大學<br>電機工程學系<br>99<br>Image compression technology has long been an important part in image processing, since uncompressed image files usually take up huge amount of storage space and are very time-consuming to transfer through networks. The arc-based fractal coding is a near lossless image compression technique suitable for medical and geographic imaging applications. This thesis presents the design and implementation of an embedded system for arc-based fractal coding. For the embedded system to benefit from hardware acceleration while preserving the flexibility of software implementation, we adopt a hardware/software integrated design approach.
The arc-based fractal coding works as follows. In the encoding phase, an image is partitioned into a collection of range blocks, and a set of arcs are created. The best match for a given range block is searched in the set of arcs. The set of affine transformations is then stored in a codebook. In the decoding phase, the image is reconstructed iteratively according to the codebook.
In this research, both the grayscale image transformation and the generation of fractal code are implemented in hardware circuits. The rest of the processing is done in software, which has been developed on the Nios II IDE. To strengthen the system capability, we have also ported a version of μClinux OS. For performance reason, we select the fast-type Nios II CPU which operates at a clock rate of 50 MHz. With the Altera SOPC technology, hardware modules are integrated into the Nios II processing environment through the Avalon Bus architecture.
Our hardware implementation platform is Terasic DE2-35 development board featuring an Altera Cyclone II FPGA EP2C35F672C6. A total of 100 medical or fractal image samples have used for function verification. Experimental results show that all images can be compressed and reconstructed almost perfectly. The average processing time per image is about 1.5 seconds. With hardware and software working together, processing speed gain is 6.6-fold over pure software implementation, given that the program is executed on the Nios II platform. The experiment shows that the proposed embedded system design and implementation has succeeded in executing the arc-based fractal coding scheme.
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楊世權. "Research of Fabrication Copper Nanofluid by Plasma Arc System." Thesis, 2011. http://ndltd.ncl.edu.tw/handle/13634383109450458847.
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碩士<br>國立臺灣師範大學<br>機電科技研究所<br>99<br>The purpose of experiment is aim to a methods of nanofluid produce by arc plasma. Refer to previous research data and correction. Consist with several stages: preparation, modification, system installation, tested; use “Evaporation synthesi- zed condensation system” to implement copper/water nanofluid by selected high energy plasma arc that can vaporize any kind of metal as a heating source, collect vaporized nanoparticle into nanofluid collector. To avoid condensed bigger size of particle due to high temperature or cluster, take paramenter in consideration during the period of experiment; such as working current, collector function, trying to obtain process minimum and average nanoparticle.
By mean of two stage experiment, base on different current parameter (50A, 60A, 70A, 80A) collector to gain the proper nanoparticle by target meterial melting situation. Preliminary analyze to determine what type of current maybe optimum parameter. Marcoscopic results show current 60A and 70A are optimum parameter for particle collect on stage one. In the second stage, base on fixed current used three different working current plasma arc torch pulse. Then stimulate with ultrasonic after that, analyze by SEM, EDS, particle size analyzer to define which process can produce perfect nanoparticle.
As a result, working current 60A/25Hz average particle is 548nm, 70A/25Hz average particle is 3500nm, process copper/water nanofluid heating resistance test, found that heating resistance reach to -30% under water temperature 50℃, paramenter 70A/25Hz.
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Chang, Yu-Chun, and 張宇淳. "Plasma Arc System Applied In Fabricating Aluminum Oxide Nanofluid." Thesis, 2005. http://ndltd.ncl.edu.tw/handle/3tj5m5.
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碩士<br>國立臺北科技大學<br>製造科技研究所<br>93<br>This article describes a novel nanofluids manufacturing and collecting system .Different to other preparing methods, the development method cools the vaporized metal aerosol by mixing the noanparticles with pre-cooling deionized water when the aerosol flows through the designed tunnel. This experimental equipment mainly contains a plasma arc system, water cooling circulatory system, the gas inducting system and coolant collection system. The bulk metal is melt by the generated plasma arc with a high temperature up to 12000K. The gas inducting system extracts and cools the mixture fluid into the collection tank. The Al2O3 nanofluid were prepared in different experimental parameters, such as discharge circuit、collection temperature、collection method. The dimensional and material properties of nanofluid were examined by using Field Emission Gun Scanning Electron Microscope(FEG-SEM) , Transsimision Electron Microscope (TEM), Particle Size Analizer(PSA), X-RAY, EDAX. Results show that the smallest Al2O3 particle diameter 10 nm. Meanwhile the prepared nanoparticles were mixed with gasoline for combustion test in determing the effects of burning performance enhancement.
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Jung, Chiu-Po, and 邱柏榮. "Automatic Shield Metal Arc Welding System of Sliding Mode Control." Thesis, 2004. http://ndltd.ncl.edu.tw/handle/92404685000701541884.
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碩士<br>國立中央大學<br>機械工程研究所<br>92<br>Abstract
Welding is a generally method in the machine manufacture today. There are still a lot of welding works done by a master worker, specially welding steel tube. Alternating current shield metal arc welding (SWAW) is the one of the most important welding method. Any kind of metal materials could be welding, and any way could be used.
The welding performance can be improved by appropriate frequency conversion. There are several different control methods to improve this purpose. However, current feedback control in the real system is very complex. Searching for scientific or technical literature, there are focus on inert gas metal arc welding (GMAW) and inert gas tungsten arc welding (GTAW). Although Alternating current shield metal arc welding (SMAW) is widely used in industry, today. Research about the alternating current shield metal arc welding is less.
The most difficult part of SMAW is to produce the electric arc from shield metal and to keep the arc current stable. We use the Sliding Mode Control of Variable Structure Control theory in the automatic alternating current shield metal arc welding control system. Employing the advantages of the uncertain of parameter, disturbance, and robust of the sliding mode control theory to overcome the difficult of the electric arc producing and preserve the current stable.