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Cacchi, Alberto. "Valutazione dell'attività fisica tramite l'uso del Global Positioning System." Bachelor's thesis, Alma Mater Studiorum - Università di Bologna, 2017.
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Questo elaborato è stato strutturato in 3 diversi capitoli, nel capitolo 1 sono presentate informazioni generali su: che cosa sia un sistema GPS, come funzioni, i suoi principali errori e alcune implementazioni.
Il capitolo 2 riguarda i sistemi GPS indoor di nuova tecnologia e le loro applicazioni.
Mentre il capitolo 3 racchiude una analisi di alcuni studi, che riguarda l'utilità della raccolta dati, tramite sistemi GPS nell'ambito sportivo. In particolare nella prima parte si studia la validità e l'affidabilità delle misure GPS considerando l'evoluzione delle unità GPS stesse con l'aumento di frequenza di campionamento. Una volta verificati questi parametri, sono stati presi in considerazione nella seconda parte la raccolta di alcuni studi, riguardanti il monitoraggio dell'attività fisica di individui comuni in relazione all'ambiente in cui si trovano. Verificandone la qualità dei dati tramite lo studio della quantità dei dati persi. Infine nell'ultima parte viene focalizzata la ricerca sulle diverse variabili misurabili con il GPS: distanza totale, distanza relativa, velocità e carico sul corpo degli atleti, e come esse cambiano in relazione ai ruoli, alla competitività e all'età. Quest'ultima analisi è sviluppata nel contesto di vari sport di squadra.
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Schaeffer, Andrew John. "Nature of a low-velocity zone atop the transition zone in northwestern Canada." Thesis, University of British Columbia, 2009. http://hdl.handle.net/2429/11762.
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Seismic studies over the past decade have identified a S-wave low-velocity zone (LVZ) above the transition zone at various locations around the globe. This layer is hypothesized to be a lens of dense, fluid-rich silicate melt ponding atop the 410 km discontinuity, beneath the silicate melt-density crossover predicted to exist within the upper mantle. We have assembled a P- and S-receiver function (PRF and SRF, respectively) dataset from the CNSN Yellowknife Array (YKA), the CANOE array, and the POLARIS-Slave array, to quantify the physical properties and geographical extent of the layer in Northwestern Canada. In order to compute the Poisson's ratio, an important discriminant of possible composition and/or fluid content, we generated a suite of 1-D velocity models based on IASP91, but with varying thicknesses and velocity ratios for a hypothetical layer above the 410 km discontinuity. From these models we computed moveout curves for the range of slowness represented in the YKA data. A grid search was performed over the model space of interval thickness and Poisson's ratio to obtain an estimate of the model that best accounts for the data. In addition, we performed a linearized inversion of transmission coefficient amplitudes to estimate the shear velocity contrast at the bounding interfaces of the LVZ. Results indicate a LVZ of thickness 36 km with a shear velocity contrast of -7.8%, and Poisson's ratio of 0.42. In combination, these two results require an associated increase in compressional velocity into the LVZ. The Poisson's ratio lies well above the IASP91 average of 0.29-0.3 for this depth range and favours the presence of high melt or fluid fractions. Geographic profiles of PRFs and SRFs 1-D migrated to depth from CANOE and POLARIS-Slave arrays reveal 410 km and 660 km discontinuities at nominal depths with little variation in transition zone thickness. PRF results from the Slave craton indicate a potential LVZ beneath many stations at an average nominal depth of 340 km, highlighted by events from the northwest. The CANOE array SRF profile images an emergent LVZ beginning at 280 km depth dipping eastwards to 310 km approaching YKA.
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Acton, C. E. "Shear velocity structure of the India-Asia collision zone." Thesis, University of Cambridge, 2009. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.595335.
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This dissertation describes the use of a number of seismic techniques to probe further the crustal and uppermost mantle shear velocity structure of the collision zone and the undeformed Indian shield to the south. A study of Rayleigh wave fundamental mode group velocity dispersion curves for 4054 receiver-source paths across India, Tibet and surrounding regions is used to obtain high-resolution group velocity maps between 10s and 70s. The dataset provides a higher frequency content than previous global studies and, with the inclusion of long paths up to ~5000km, bridges the gap between regional and global studies. This provides better constraints on whole crustal structure. Higher frequency P to S receiver functions are used to resolve the position of the major interface beneath seismic stations across the region; most importantly the crust-mantle boundary. Joint inversion of receiver function data and group velocity dispersion data limits the non-uniqueness inherent in receiver function inversion which is highly sensitive to a depth-velocity trade-off. The receiver function study is divided into two parts, defined by geographical area. Firstly, data from a number of broadband stations deployed over the course of this research in West Bengal and Sikkim are analysed alongside data from the INDEPTHII deployment which provides a northwards extension of the profile into Tibet. Data from previous experiments in nearby Nepal and Bhutan are studied in order to give a more complete picture of the crustal structure of this region of the Himalayas. Secondly, receiver function data for a large number of stations across the South Indian shield are revisited to provide an improved and coherent picture of variations in crustal thickness across the different geological terrains. Finally, dispersion curves extracted from the series of group velocity maps produced for the region are inverted for shear velocity structure.
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Sayed, Ali Yawar. "In Situ Compressional Wave Velocity Across An Exposed Brittle Fault Zone." Thesis, Virginia Tech, 2001. http://hdl.handle.net/10919/34336.
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The effects of lithology, fracturing, and gouge zone mineralization on the geophysical properties of fault zones are not very well understood. In situ seismic data collected over the exhumed San Gregorio Fault at Moss Beach, CA were used to relate in situ compressional wave velocity to internal fault zone properties. This active strike-slip fault is exposed in cross section on an uplifting and actively eroding wave-cut platform. It cuts shallow marine sediments that have been buried to depths of a few kilometers. The unweathered exposure containing seawater makes it a unique analog of subsurface faults. Previous structural analysis over this exposure observed damage caused by faulting over a ~100 m wide zone in cross-section. The fault zone is centered at a 10-17 m wide clay-rich fault core flanked by a ~30 m wide brecciated gouge zone. These gouge zones are bordered on either side by 30-40 m wide fractured zones. Resolving to a scale of a few meters, the seismic survey produced a continuous P-wave velocity profile analogous to a horizontal well log across the fault. Lateral variations in the velocity profile correlate exactly to previously mapped fault zone structure. The clay core and adjacent brecciated gouge create a ~50 m wide very low velocity zone, 25-50% slower than the surrounding host rock. Fractured bedrock on either side of the core causes a wider zone of 5-10% slow velocity, for a total fault signature ~100 m wide. Fault parallel fracture anisotropy was observed in the fractured zones, but surprizingly anisotropy was not observed in the strongly foliated gouge zones. The field measurements differ significantly from laboratory measurements at zero pressure and in some cases from expected values for saturated rock of this porosity, perhaps due to biased rock sampling, the long wavelength effects of macrofractures, frequency dispersion, and partial saturation. The velocity profile is similar in width and consistent in velocity contrast to low S-wave velocity zones derived from fault zone guided waves in other strike-slip faults. The traveltime delay across the fault zone is not large enough to cause the 2-3 km wide crustal low velocity zones modeled by refraction studies. Synthetic reflection seismograms in the typical frequency range show that the fault zone acts as a thick bed or as a constructively interfering thin bed. The models suggest that very large reflection coefficients observed across accretionary prism faults can be explained by fracturing, brecciation and clay content without elevated pore pressures. Comparison with a refraction study across the Punchbowl Fault shows a similar structural zonation of these two well-studied examples of brittle fault zones. This suggests that high-resolution seismic velocity models can be used to directly interpret internal deformation structure of brittle faults.Master of Science
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Taylor, Rochelle Louise. "Acoustic velocity structure of the carboneras fault zone, SE Spain." Thesis, University of Manchester, 2013. https://www.research.manchester.ac.uk/portal/en/theses/acoustic-velocity-structure-of-the-carboneras-fault-zone-se-spain(63a8ae72-04e3-4ab8-bf38-dc215cabbeec).html.
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The Carboneras fault zone (CFZ, Almería Province, SE Spain) is a major NE-SW trending tectonic lineament that marks part of the diffuse plate boundary between Iberia and Africa. Developed within a basement terrain dominated by mica schist, the fault system comprises two main strands within a complex zone up to 1 km wide. Between these two strands is a braided network of left-lateral strike-slip, phyllosilicate-rich fault gouge bands, ranging between 1 and 20 m in thickness, passively exhumed from up to 3 km depth. The excellent exposure in a semi-arid environment, the wide range of rock types and fault structures represented and the practicality of carrying out in-situ geophysical studies makes this fault zone particularly well suited to verifying and interpreting the results of in-situ seismic investigations. Integration of elements of field study, laboratory analysis and modelling has aided interpretation of the internal structure of the fault zone. Ultrasonic measurements were made using standard equipment over confining and pore pressure ranges appropriate to the upper 10 km of the continental crust. Seismic velocities have also been approximated from modal analysis and mineral phase elastic properties and adjusted for the effects of porosity. In-situ seismic investigations recorded P-wave velocities 40-60% lower than those measured in the laboratory under corresponding pressures and at ambient temperatures for hard rock samples. Fault gouge velocities measured in the laboratory, however, are comparable to those measured in the field because, unlike the host rocks, fault gouges are only pervasively micro-fractured and lack the populations of long cracks (larger than the sample size) that cause slowing of the velocities measured in the field. By modelling the effect of fractures on seismic velocity (by superimposing upon the laboratory seismic data the effects of crack damage) the gap between field- and laboratory-scale seismic investigations has been bridged. Densities of macroscopic cracks were assessed by measuring outcrop lengths on planar rock exposures. Assuming crack length follows a power law relation to frequency, this fixes a portion of the power spectrum, which is then extrapolated to cover the likely full range of crack sizes. The equations of Budiansky and O'Connell (1976), linking crack density to elastic moduli, were used to calculate modified acoustic velocities, and the effects of the wide range of crack sizes were incorporated by breaking the distribution down into small sub-populations of limited range of crack density. Finally, the effect of overburden pressure causing progressively smaller cracks to close was incorporated to predict velocity versus depth of burial (i.e. pressure). Determination of rock physical properties from laboratory analysis and sections constructed from geological mapping provides a representation of velocity from selected parts of the Carboneras fault zone. First break tomography images show particularly well the location of steeply-inclined fault cores, and these correlate generally well with geological mapping and laboratory velocity measurements corrected for the effect of cracks. The decoration of the fault zone with intrusive igneous material is well correlated with the results of geological observations. Comparisons made between the field (seismic) inversion model and laboratory forward velocity model in El Saltador valley show the laboratory and field velocity measurements made within the fault zone can be reconciled by accounting for the effects of crack damage in field data.
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Wu, Jiedi. "New Constraints on Fault-Zone Structure from Seismic Guided Waves." Diss., Virginia Tech, 2008. http://hdl.handle.net/10919/28873.
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The structure of fault zones (FZs) plays an important role in understanding fault mechanics, earthquake rupture and seismic hazards. Fault zone seismic guided waves (GW) carry important information about internal structure of the low-velocity fault damage zone. Numerical modeling of observed FZGWs has been used to construct models of FZ structure. However, the depth extent of the waveguide and the uniqueness of deep structure in the models have been debated. Elastic finite-difference synthetic seismograms were generated for FZ models that include an increase in seismic velocity with depth both inside and outside the FZ. Strong GWs were created from sources both in and out of the waveguide, in contrast with previous homogenous-FZ studies that required an in-fault source to create GW. This is because the frequency-dependent trapping efficiency of the waveguide changes with depth. The near-surface fault structure efficiently guides waves at lower frequencies than the deeper fault. Fault structure at seismogenic depth requires the analysis of data at higher frequencies than the GWs that dominate at the surface. Adapting a two-station technique from surface wave studies, dispersive differential group arrival times between two earthquakes can be used to solve for FZ structures between the earthquakes. This method was tested with synthetic data and shallow events recorded in the SAFOD borehole in the San Andreas Fault. A pair of deep earthquakes recorded in the SAFOD borehole indicate a ~150 m wide San Andreas Fault waveguide with >20% velocity contrast at 10-12 km depth. With additional earthquakes, the full FZ structure at seismogenic depth could be imaged. Subsurface FZ structure can also be derived from a surface source and receiver array analogous to a body-wave refraction survey. Synthetic seismograms for such source-receiver geometry were generated and verified that FZGWs are refracted by the increase in velocity with depth. Synthetic data from a surface array were successfully inverted to derive FZ structure in the subsurface. The new methods presented in this dissertation extend the potential of FZGWs to image deeper FZ structure than has been uniquely constrained in the past.Ph. D.
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Collings, Rachel Elizabeth. "The Sumatra subduction zone : seismicity, velocity structure and seismic anisotropy." Thesis, University of Liverpool, 2012. http://livrepository.liverpool.ac.uk/7233/.
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On September 12 2007, an Mw 8.4 earthquake occurred within the southern section of the Mentawai segment of the Sumatra subduction zone, where the subduction thrust had previously ruptured in 1833 and 1797. Following the 2007 rupture, a temporary local network was installed in the Mentawai region between December 2007 and October 2008 to record the aftershocks. Additionally, a second network was installed in central Sumatra between April 2008 and February 2009. In this study the data obtained from the Mentawai network were used to determine 2D and 3D Vp and Vp/Vs models, first motion polarity focal mechanisms and accurate hypocentre locations. In addition to this, shear wave splitting (SWS) measurements from both networks were used to determine the type, amount and location of anisotropy. This has enabled us to obtain a detailed image of the structure of the subduction zone, ascertain the down-dip limit of the seismogenic zone and determine the deformation occurring. The forearc islands are characterized by a low Vp (4.5-5.8 km/s) and a high Vp/Vs ratio (>2.0), suggesting that they consist of fluid-saturated sediments. The down-going slab is clearly distinguished by a dipping region of high Vp (8.0 km/s), which can be traced to ~50 km depth, with an increased Vp/Vs ratio (1.75 to 1.90) beneath the forearc islands and the western side of the forearc basin, suggesting hydrated oceanic crust. Beneath the slab, a ~150 km thick layer of sub-slab anisotropy has developed due to the oceanic asthenosphere being entrained by the subducting slab. Two clusters of seismic activity are found within the ~25-30 km thick overriding crust. The location of the first cluster confirms that the Mentawai Fault is active and may accommodate backthrust movement, while the second cluster suggests a backthrust may be present on the eastern side of the forearc basin. Local SWS measurements suggest that in the overriding plate, adjacent to the Sumatran Fault, a layer of anisotropy has formed from fault-parallel aligned fractures and minerals. Beneath the forearc, a shallow continental Moho of < 30 km depth can be inferred. Within the mantle wedge there is no widespread serpentinization; only localized serpentinization is present at the toe. Beneath the backarc, 2D corner flow is occurring in the continental asthenosphere. The co-seismic slip of the 2007 events, as well as the aftershock distribution, suggests that the down-dip limit to rupture propagation is beneath the slab-Moho intersection at ~50 km depth. Consequently, as the Mw 7.7 Mentawai earthquake on 25 October 2010 showed that the updip limit of the seismogenic zone is at the trench, a potential 200 km wide rupture could take place.
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Beale, Jacob N. "Local Earthquake Tomography at Mt. Pinatubo, Philippines." Thesis, Virginia Tech, 2004. http://hdl.handle.net/10919/34635.
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A new high-resolution 3-dimensional P-wave velocity model for Mt. Pinatubo volcano was developed by tomographic inversion of P-wave arrivals from 3,007 earthquakes recorded during a four month period from May to August, 1991. The arrivals were recorded by a network of seismic stations, consisting of seven pre-eruption stations and seven post-eruption stations. Two stations survived the June eruptions. First-arrival travel times were calculated using a finite-difference solution to the eikonal equation. An iterative, linearized approximation of the nonlinear tomography problem was used to solve separately for both velocity structure and hypocenter locations. Several inversions performed with different initial parameters and convergence schemes, and synthetic checkerboard reconstructions indicate a horizontal spatial resolution of velocity perturbations near 4 km. However, the network sparseness allows for a substantial trade-off between focal depth, origin time, and the vertical velocity profile. Many hypocenter clusters collapse from diffuse clouds into tighter features after 3-D relocation. These bands of earthquakes appear to represent fault-related structures. Three low-velocity (relative to the horizontal average) anomalies exist within the well-resolved portion of the velocity model. These anomalies are spatially associated with pre- and post-eruption earthquakes oriented along mapped surface fault zones. Similar anomalies observed at different volcanoes have been previously interpreted as magma related. The low-velocity anomalies at Pinatubo are interpreted as highly fractured, hot volumes of mostly competent rock, which may contain partial melt.Master of Science
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Hansen, Ralf Theodor Johannes. "Nature of the low velocity zone in Cascadia from receiver function waveform inversion." Thesis, University of British Columbia, 2011. http://hdl.handle.net/2429/37984.
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Dipping low-velocity zones (LVZs) are a ubiquitous structural element of subduction zones worldwide. In this study we map seismic attributes characterizing the LVZ beneath the Cascadia subduction zone from northern Vancouver Island to northern California using receiver function waveform inversion. Throughout this region, the LVZ is characterized by high Vp/Vs ratios (mean=2.77), strong S-velocity contrasts (~50%) and thicknesses averaging 3.38 km. The LVZ is immediately underlain by a second, weaker layer exhibiting moderate Vp/Vs ratios (mean=1.85) with mean thickness of 4.62 km. We interpret the combined structure in terms of subducting oceanic crust, based on classical structural/petrological descriptions and constraints from previous studies of ophiolites and ocean drill cores. The LVZ is identified with pervasively hydrated, high porosity pillow basalts and sheeted dikes of Layer 2 with possible contributions from sediments (Layer 1). Fluids released from metamorphic dehydration reactions are maintained near lithosphere fluid pressures through an impermeable plate boundary above, and a low porosity, gabbroic/mafic-cumulate dominated Layer 3 below.
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Garth, Thomas. "The seismic velocity structure of the Wadati-Benioff Zone : insights from guided waves." Thesis, University of Liverpool, 2014. http://livrepository.liverpool.ac.uk/17863/.
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Low velocity hydrous minerals in the subducting plate deliver water to the mantle and are thought to cause intermediate depth Wadati-Benioff zone (WBZ) seismicity through dehydration embrittlement. High frequency seismic energy (> 2 Hz) from intermediate depth earthquakes that occur within this low velocity oceanic crust is retained and delayed by the crustal waveguide while lower frequency (< 0.5 Hz) energy travels at the faster velocities of the surrounding mantle. These guided waves therefore spend longer interacting with the low velocity oceanic crust than any other seismic phase, and have the potential to reveal a large amount about the velocity structure of the WBZ. Dispersive arrivals recorded in the forearc of Northern Japan are directly compared to synthetic waveforms produced from full 2D and 3D waveform simulations. Comparing the relative amplitude and arrival time of a given frequency using the velocity spectra and spectrogram respectively, allows the full dispersive P-waveform to be constrained. Analysis of dispersive arrivals from upper plane WBZ events at 150 – 220 km depth place the first observational constraints on the metamorphic reactions occurring before full eclogitisation of the subducting oceanic crust. I show that blueschist and lawsonite bearing rocks may persist well beyond the depths inferred from established thermo-petrological subduction zone models, and that full eclogitization may occur at much greater depths than is inferred by receiver function studies. The persistence of meta-stable hydrous minerals explains the occurrence of WBZ seismicity at 200 - 250 km depth, and may be due to the partially hydrated oceanic crust. Dispersion from events that occur well below the upper plane of WBZ seismicity can be explained by the occurrence of low velocity hydrated outer rise normal faults at intermediate depths. At depth, these faults are inferred to be 2 - 3 km thick and 12 - 15 % slower that the surrounding mantle, suggesting they are 50 - 71 % serpentinised. We suggest that the extended P-wave coda observed at stations close to the trench in Northern Japan are explained by low velocity dipping faults of a range of scale lengths forming a scattering medium. This scattering medium is simulated using a von Kármán function, and the synthetic waveforms produced are compared to the observed P-wave coda, that decays in amplitude with distance from the trench. The magnitude of this spatial coda decay is sensitive to the average bulk velocity of the scattering medium and provides a constraint on the hydration of the lithospheric mantle subducted beneath Japan. This first in-situ constraint on the degree of slab mantle hydration at intermediate depth suggests that 170.4 - 318.7 Tg/Myr/m of water is subducted beneath Northern Japan by the slab mantle. In summary we have shown that up to 94 % of the water subducted beneath Northern Japan is transported by the lithospheric mantle, and that upper and lower planes of WBZ zone seismicity are directly related to hydrous mineral assemblages, and so may occur through dehydration embrittlement. This work shows that guided waves have the potential to resolve new details of the WBZ velocity structure and the techniques developed here can be applied to other subduction zone settings.
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Maia, Kisner Anderson. "Influência da velocidade de entrada na zona de contato na eficiência de clarificação de unidades retangulares de flotação por ar dissolvido aplicado no tratamento de águas para abastecimento." Universidade de São Paulo, 2010. http://www.teses.usp.br/teses/disponiveis/18/18138/tde-12112010-103728/.
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A flotação por ar dissolvido (FAD) é reconhecida atualmente como técnica eficiente para a etapa de clarificação em sistemas de tratamento de água para abastecimento. Diversos estudos vêm sendo realizados para aprimoramento dessa técnica e das características físicas das unidades FAD. Seguindo essa tendência, o presente trabalho teve como objetivo estudar os efeitos da velocidade na entrada da zona de contato (\'V IND.EZC\') na eficiência de clarificação de unidades retangulares FAD. Para o presente estudo foi utilizada água sintética preparada através da adição de 1,0 mg/L de ácido húmico e 8,5 mg/L de caulinita, a qual foi coagulada com sulfato de alumínio. A pesquisa foi dividida em duas fases: FASE I - com o emprego do Flotateste foram determinadas as dosagens adequadas de coagulante, o pH adequado de coagulação com a medição do potencial zeta das partículas (PZ), o gradiente médio de velocidade para floculação e o tempo médio para floculação para o tratamento da água sintética em estudo; FASE II - utilizando unidade FAD em escala piloto foram realizados ensaios para diferentes variações na altura da entrada da zona de contato (he) da câmara de flotação de forma a se obter diferentes valores de \'V IND.EZC\'. Nesta fase foram investigadas duas diferentes condições de coagulação as quais forneceram bons resultados por flotação: 1ª condição, aplicação de 42,5 mg/L de \'AL IND.2\'(\'SO IND.4\')IND.3\' e pH de 6,35 \'+ OU -\' 0,05 na qual resultou em PZ positivo em torno de +10 mV e para 2ª condição, aplicação de 22,5 mg/L de \'AL IND.2\'(\'SO IND.4\')IND.3\' e pH de 6,40 \'+ OU -\' 0,05 na qual resultou em PZ próximo de 0 mV. Os ensaios foram monitorados e comparados entre si os valores residuais de turbidez e cor aparente. Em todos os ensaios as taxas de aplicação superficial foram mantidas em faixas estreitas de verificando-se que os melhores resultados residuais dos parâmetros monitorados foram obtidos para a 1ª condição de estudo com valores de 0,66 NTU de turbidez e cor aparente igual a 2 uC (eficiências de 90,5 e 93,9% respectivamente). Os resultados demonstraram que para a faixa de valores de \'V IND.EZC\' entre 62,2 e 12.432,4 m/h pouca influência desse parâmetro foi observada na eficiência do processo de clarificação por flotação para ambas as condições de coagulação investigadas. Entretanto, a faixa de valores de \'V IND.EZC\' entre 124,3 e 180,2 m/h forneceram as melhores condições de flotação. Portanto, sugere-se tal faixa de valores como subsídio ao projeto de sistemas de flotação constituído pelas características apresentadas nesta pesquisa.Dissolved air flotation (DAF) is currently recognized as an efficient technique for water clarification in water treatment systems. Several studies have been conducted to improve this technique and the physical characteristics of DAF units in order to constantly improve their performance. Following this trend, the aim of this research was to evaluate the effects of the velocity in the contact zone entrance on the clarification efficiency of rectangular DAF units. A DAF pilot plant fed with synthetic water prepared by adding 1.0 mg/L of humic acid and 8.5 mg/L of kaolin, and coagulated with aluminum sulfate was used. The research was divided into two phases: I) by using a laboratory scale DAF unit (Flotatest) the optimal coagulation, flocculation, and flotation conditions for the synthetic water previously described were investigated; and II) by using a DAF pilot unit tests were performed for different variations in the height of the contact zone entrance (he) of the flotation chamber to obtain different values of velocity in the contact zone entrance. In this phase two different conditions of coagulation were investigated yielding good results: 1st condition: application of 42.5 mg/L of \'AL IND.2\'(\'SO IND.4\')IND.3\' and pH 6.35 \'+ OR -\' 0.05, which resulted in zeta potential of positive particles around +10 mV, and 2nd condition: application of 22.5 mg/L \'AL IND.2\'(\'SO IND.4\')IND.3\' and pH 6.40 \'+ OR -\' 0.05, which resulted in zeta potential of particles near zero. The tests were monitored and the residual values of turbidity and apparent color were compared. In all experiments, the hydraulic surface loadings were kept in narrow bands of values (in the contact zone equal to 180 \'+ OR -\' 4 m/h and in the clarification zone, equal to 184 \'+ OR -\' 4 m/d). It was verified that the best residual results of the parameters monitored were obtained for the 1st condition with 0.66 NTU turbidity and apparent color equal to 2 uC (efficiencies of 90.5 and 93.9%, respectively). The results showed that for the range of values of velocity in the contact zone entrance between 62.2 and 12432.4 m/h little influence of this parameter was observed on the clarification efficiency process by flotation for both coagulation conditions investigated. However, as the range of values between 124.3 and 180.2 m/h provided the best flotation conditions, such a range should be adopted for the designs of rectangular DAF units.
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Ozer, Ceren. "Investigation Of Hydrodynamic Demands Of Tsunamis In Inundation Zone." Master's thesis, METU, 2007. http://etd.lib.metu.edu.tr/upload/12608182/index.pdf.
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This thesis analyzed the new parameter hydrodynamic demand representing the damage of tsunami waves on structures and coastlines,maximum positive amplitudes and current velocities occurred during tsunami inundation by using the numerical model TUNAMI-N2. Regular shaped basins were used with two different bottom slopes in analyses in order to understand the behaviour of tsunami wave and investigate the
change of important tsunami parameters along different slopes during tsunami inundation. In application, different initial conditions were used for wave profiles such as solitary wave, leading elevation single sinusoidal wave and leading depression sinusoidal wave. Three different initial wave
amplitudes were used in order to test the change of distribution of the hydrodynamic demand. The numerical results were compared and discussed with each other and with the results of existing analytical and experimental studies.
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Zhao, Peng. "Seismic velocity contrasts and temporal changes of strike-slip faults in central California." Diss., Georgia Institute of Technology, 2010. http://hdl.handle.net/1853/37242.
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The spatial patterns of bimaterial interfaces along the Parkfield section of the San Andreas Fault (SAF) and central section of the Calaveras Fault are systematically investigated with large data sets of near-fault waveforms. Different from the usage of direct P and S waves in traditional tomographic studies, a particular seismic phase named fault zone head wave (FZHW) is used to image the bimaterial fault interfaces. The results show clear variations of seismic velocities contrast both along-strike and along-depth directions in both regions, which is in general consistent with local geological setting at surface and existing 3D tomography results. In the Parkfield section of SAF, the result of velocity contrast is used to test the relationship between preferred rupture directions of M6 Parkfield earthquakes and bimaterial interface. Strong velocity contrast (~5-10%) near Middle Mountain (MM) could control the rupture directions of nearby earthquakes to SE, such as the case for 1966 M6 Parkfield earthquake. In comparison, weak velocity contrast (~0-2%) near the epicenter of the 2004 Parkfield M6 earthquake (i.e., Gold Hill) probably has no influence on controlling its rupture direction, which is consistent with the bilateral rupture of the 2004 Parkfield earthquake. In the central Calaveras Fault, a detailed analysis of the moveout between FZHWs and direct P waves revealed the existence of a complicated fault structure with velocity contrast increasing from NW to SE of station CCO. The high velocity contrast SE of station CCO could be caused by a low-velocity zone SE of station CCO.
The spatio-temporal variations of seismic velocity around the central Calaveras Fault and its nearby region are investigated based on the waveform analysis of 333 repeating clusters following the 1984 ML6.2 Morgan Hill earthquake. Clear reduction of seismic velocity is shown for all repeating clusters immediately after the mainshock, followed by a logarithmic recovery. The coseismic change mostly occurs at shallow layers (top few hundred meters) for the region away from the rupture area of the mainshock, but extends much deeper around the rupture zone of the Morgan Hill earthquake. The estimated depth of the damage zone is up to 6 km in the fault based on the repeating clusters directly beneath station CCO.
Finally, temporal changes around the Parkfield section of SAF are studied using recently developed ambient noise cross-correlation technique. The extracted daily empirical Green functions (EGFs) from 0.4-1.3 Hz noise records are used to estimate subtle temporal changes associated with large earthquakes from local to teleseismic distances. The results show clear coseismic reduction of seismic velocities after the 2004 M6 Parkfield earthquake, similar to the previous observation based on repeating earthquakes. However, no systematic changes have been detected for other four regional/teleseismic events that have triggered clear tremor activity in the same region. These results suggest that temporal changes associated with distance sources are very subtle or localized so that they could not be detected within the resolution of the current technique (~0.2%).
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Kawasumi, T., H. Shimizu, Y. Yokomizu, and T. Matsumura. "Novel measurement methods of propagation velocity and direction of normal zone in ac superconducting wire." IEEE, 2000. http://hdl.handle.net/2237/6780.
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Marr, David. "Velocity measurements in the breathing zone of a moving thermal manikin within the indoor environment." Related electronic resource, 2007. http://proquest.umi.com/pqdweb?did=1375538061&sid=1&Fmt=2&clientId=3739&RQT=309&VName=PQD.
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Rhodes, Mark. "Mantle seismic tomography using P-wave travel times and a priori velocity models." Thesis, University of Liverpool, 1998. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.266489.
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Mantle seismic tomography has historically relied on radially symmetric ID velocity models to trace ray paths through the mantle. The resulting travel time residuals are used to invert for seismic velocity perturbations around this 1D model. However, we know the Earth deviates from such ID velocity models; for example there are global variations in crustal thickness; in the age of oceanic lithosphere and presence of subducting oceanic lithosphere. In light of this, an a priori model which incorporated the three types of surface observable heterogeneity outlined above was constructed as part of this thesis. Tracing ray paths through this more heterogeneous starting model resulted in new travel time residuals which were subsequently employed in a simultaneous tomographic inversion solving for earthquake relocation parameters and slowness perturbations. This inversion method allows us to investigate whether tomography using a priori models results in improved images of mantle velocity perturbations and systematic earthquake relocations. A graphical earthquake browser was specifically written to establish, in a consistent manner, the shape of subducting oceanic lithosphere for all the major subduction zones. The resulting population of earthquakes, which best represent the shape of Wadati-Benioff zones, were subsequently interpolated into profiles following the path of oceanic lithosphere as it subducts. The temperature field in and around each profile was generated using a new analytic solution of the heat equation for subducting lithosphere, adapted to incorporate slab shape. The upper mantle a priori model was constructed on an equal area tomographic grid by combining the thermal models of the subducting lithosphere, plate cooling models of oceanic lithosphere and variations in crustal thickness away from that prescribed in a ID velocity model. Efficient 20 ray tracing through the a priori model was achieved via the adaptation of a ID ray tracer by perturbing the reference ID model, iasp91, using the a priori velocities in the cells connecting the event to the recording station for each ray. A new travel time residual was calculated and subsequently used in the simultaneous solution for slowness perturbation and earthquake relocation. So as not to bias the earthquake relocation procedure, phases were selected so as to maximise the azimuth and epicentral distance coverage, while minimising the number of duplicated ray paths which would be redundant in the inversion. The data selection resulted in some 3,450 events emitting 785,000 teleseismic P phases (bottoming in the lower mantle). The cell based SIRT inversion procedure, used to solve the standard system of linear tomographic equations, was augmented by explicit damping and smoothing matrices so as to control both poorly resolved cells and the relative importance between earthquake relocation parameters and slowness perturbations. For comparison, the ray population was also traced through the 3SMAC upper mantle model before undertaking a similar inversion. The 5° x 5° equal area, 100 km thick, cell inversions resulted in systematic earthquake relocations with an average relocation distance of= 5 km. In the upper mantle, the inversion procedure adjusts the a priori subducting slab velocity contrast, revealing images of subducting oceanic lithosphere. In the lower mantle, there is little difference between inversions produced in this thesis and those available digitally. Some of the main features are the pronounced lineations interpreted as the Farallon slab (beneath North and South America) and the Tethys (beneath Eurasia) clearly imaged between 1200 and 1500 km depth. All inversions undertaken in this thesis image hotspots throughout the upper mantle, and in places these pronounced slow features are observed passing through the upperllower mantle transition. A section through the South Pacific superswell images slow material as a continuous body, to at least 1300 km. Synthetic recovery tests indicate these hotspot features are well resolved.
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Okamoto, Tatsuto, Ikuro Sumita, Tomoeki Nakakuki, and Shigeo Yoshida. "Deformation of a partially molten D” layer by small-scale convection and the resulting seismic anisotropy and ultralow velocity zone." Elsevier, 2005. http://hdl.handle.net/2237/13018.
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Smith, Ernest Ray. "Longshore sediment transport rate calculated incorporating wave orbital velocity fluctuations." Texas A&M University, 2006. http://hdl.handle.net/1969.1/4182.
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Laboratory experiments were performed to study and improve longshore sediment
transport rate predictions. Measured total longshore transport in the laboratory was
approximately three times greater for plunging breakers than spilling breakers. Three
distinct zones of longshore transport were observed across the surf zone: the incipient
breaker zone, inner surf zone, and swash zone. Transport at incipient breaking was
influenced by breaker type; inner surf zone transport was dominated by wave height,
independent of wave period; and swash zone transport was dependent on wave period.
Selected predictive formulas to compute total load and distributed load transport
were compared to laboratory and field data. Equations by Kamphuis (1991) and Madsen
et al. (2003) gave consistent total sediment transport estimates for both laboratory and
field data. Additionally, the CERC formula predicted measurements well if calibrated
and applied to similar breaker types. Each of the distributed load models had
shortcomings. The energetics model of Bodge and Dean (1987) was sensitive to
fluctuations in energy dissipation and often predicted transport peaks that were not
present in the data. The Watanabe (1992) equation, based on time-averaged bottom stress, predicted no transport at most laboratory locations. The Van Rijn (1993) model
was comprehensive and required hydrodynamic, bedform, and sediment data. The
model estimated the laboratory cross-shore distribution well, but greatly overestimated
field transport.
Seven models were developed in this study based on the principle that transported
sediment is mobilized by the total shear stress acting on the bottom and transported by
the current at that location. Shear stress, including the turbulent component, was
calculated from the wave orbital velocity. Models 1 through 3 gave good estimates of
the transport distribution, but underpredicted the transport peak near the plunging wave
breakpoint. A suspension term was included in Models 4 through 7, which improved
estimates near breaking for plunging breakers. Models 4, 5 and 7 also compared well to
the field measurements.
It was concluded that breaker type is an important variable in determining the
amount of transport that occurs at a location. Lastly, inclusion of the turbulent
component of the orbital velocity is vital in predictive sediment transport equations.
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Murphy, Justin James. "Kinematics, partitioning and the relationship between velocity and strain in shear zones." Online access for everyone, 2007. http://www.dissertations.wsu.edu/Dissertations/Summer2007/j_murphy_061907.pdf.
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Lucchi, Andrea. "Numerical simulation of low velocity impact on fiber metal laminates." Master's thesis, Alma Mater Studiorum - Università di Bologna, 2017.
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The diffusion of composite laminates in aerospace industry has been slowed down by complexity in the prediction of fracture behaviours. In this respect the delamination phenomenon caused by Low-Velocity Impacts has been a critical issue. Several criteria that predict the delamination onset and growth have been analysed. The subsequent study has been focused on Cohesive Zone Models able to predict both initiation and propagation of delamination. Several models that represent the dynamic response of composite structures to impacts have been presented. An explicit FEM has been developed to perform 3D simulations of different layup configurations of Al2024T3 and Woven Carbon Prepreg Laminates subjected to a Low-Velocity Impact. ABAQUS, Dassault Systèmes Simulia Corp. has been employed to perform the numerical simulations. Specific attention is paid to the cohesive failure representing delamination.
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Marsh, Oliver John. "Ice dynamics and mass balance in the grounding zone of outlet glaciers in the Transantarctic Mountains." Thesis, University of Canterbury. Gateway Antarctica, 2013. http://hdl.handle.net/10092/8722.
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The Antarctic grounding zone has a disproportionately large effect on glacier dynamics and ice sheet stability relative to its size but remains poorly characterised across much of the continent. Accurate ice velocity and thickness information is needed in the grounding zone to determine glacier outflow and establish to what extent changing ocean and atmospheric conditions are affecting the mass balance of individual glacier catchments.
This thesis describes new satellite remote sensing techniques for measuring ice velocity and ice thickness, validated using ground measurements collected on the Beardmore, Skelton and Darwin Glaciers and applied to other Transantarctic Mountain
outlet glaciers to determine ice discharge. Outlet glaciers in the Transantarctic Mountains provide an important link between the East and West Antarctic Ice Sheets but remain inadequately studied. While long-term velocities in this region
are shown here to be stable, instantaneous velocities are sensitive to stresses induced by ocean tides, with fluctuations of up to 50% of the mean observed in GPS measurements. The potential error induced in averaged satellite velocity measurements due to these effects is shown to be resolvable above background noise in the grounding zone but to decrease rapidly upstream. Using a new inverse finite-element modelling
approach based on regularization of the elastic-plate bending equations, tidal flexure information from differential InSAR is used to calculate ice stiffness and infer thickness in the grounding zone. This technique is shown to be successful at reproducing the thickness distribution for the Beardmore Glacier, eliminating current issues in the calculation of thickness from freeboard close to the grounding line where ice is not in hydrostatic equilibrium. Modelled thickness agrees to within 10% of ground penetrating radar measurements. Calibrated freeboard measurements and tide-free velocities in the grounding zones of glaciers in the western Ross Sea are used to calculate grounding zone basal melt rates, with values between 1.4 and 11.8 m/a⁻¹ in this region. While strongly dependent on grounding line ice thickness and velocity, melt rates show no latitudinal trend between glaciers, although detailed error analysis highlights the need for much improved estimates of firn density distribution in regions of variable accumulation such as the Transantarctic Mountains.
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Souza, Irene Monteiro da Franca. "Influência do gradiente médio de velocidade na zona de contato na eficiência de clarificação de água para abastecimento por flotação." Universidade de São Paulo, 2012. http://www.teses.usp.br/teses/disponiveis/18/18138/tde-17102012-103326/.
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O presente trabalho teve como objetivo estudar a influência do gradiente médio de velocidade (Gzc), associado ao tempo de detenção hidráulico (tzc) e à taxa de aplicação superficial (TASzc), na zona de contato, na eficiência de clarificação de uma unidade retangular de flotação por ar dissolvido, em escala piloto, tratando água para abastecimento. Foram estudadas duas configurações da Unidade Piloto de Flotação por Ar Dissolvido (UPFAD) (A e B), as quais diferem no comprimento da zona de contato A (90 mm) e B (140 mm). A TASzc - A (133 ± 3 m/h) e B (86 ± 1 m/h) - e o tzc - A (54 ± 1s) e B (84 ± 1 s) - são diferentes. Foram avaliados três valores do Gzc A (1,8; 6,5;10,2) e B (0,9; 4,7; 6,3), através da inserção de telas com características diferentes no interior da zona de contato. E, Para cada valor de Gzc, foram investigados três valores de A/V (3,73; 4,90; 6,41). Em todos os ensaios realizados, foram fixados os seguintes parâmetros: vazão da água bruta preparada (5,4 m³/h); temperatura da água bruta preparada (26 ± 1ºC); pH de coagulação (6,5 ± 0,1); tempo de floculação (17,2 min); gradiente médio de velocidade de floculação (110 s-1); vazão de descarte após a floculação (0,8 m³/h); vazão de entrada para a flotação (Qe) (4,6 m³/h); velocidade de entrada para a flotação (ve) (180 m/h); velocidade cross-flow (45 m/h); TASzs (14,6 ± 0,2 m/h); pressão de saturação (4,5 ± 0,1 Kgf/cm²). A unidade piloto FAD foi alimentada com água preparada, que apresentou turbidez em torno de 7,4 ± 0,6 UNT, e cor aparente, em torno de 39,4 ± 4,3 UH. A fração removida dos parâmetros analisados para cada Gzc é menos sensível a variações de A/V na configuração A que na configuração B. Na configuração A, a tela que apresentou Gzc em torno de 6,5 s-1 gerou melhores resultados para cada A/V analisado. Na configuração B, a tela que gerou Gzc em torno de 4,7 s-1 proporcionou melhor fração removida de turbidez e cor para cada A/V estudado. Além disso, na configuração B, a fração removida de turbidez e cor foi menos sensível a variações de A/V, para Gzc de 4,7 s-1 que para os demais valores de Gzc. A tela que gerou resultados mais eficientes na configuração A foi a mesma para a configuração B. Portanto o uso da referida tela favoreceu o desempenho das configurações A e B. Comparando todas as situações estudadas nas duas configurações, o ensaio com a configuração A (com tzc de 54 s) com Gzc de 6,3 s-1 e A/V de 4,9 g/m³, apresentou as maiores frações de remoção de cor e turbidez.The present work aimed to study the influence of velocity gradient (Gzc) associated with the hydraulic detention time (tzc) and the rate of surface application (TASzc) in the contact zone in the efficiency of clarification of a unit rectangular dissolved air flotation pilot scale, treating water supplies. Two different kinds of configurations of the reactor dissolved air flotation in pilot scale (UPFA) (A and B) were studied, which differ in the length of the contact zone - A (90 mm) and B (140 mm). The TASzc - A (133 ± 3 m/h) and B (86 ± 1 m/h) - and tzc - A (54 ± 1 s) and B (84 ± 1 s) were different. Three different values of Gzc were analysed - A (1.8, 6.5, 10.2 s-1) and B (0.9, 4.7, 6.3 s-1) by insertion of grilles with different characteristics within the zone contact. And for each value of Gzc, three values of A/V (3.73, 4.90, 6.41 g/m³) were investigated. In all trials, the following parameters were set: flow of synthetic raw water (5.4 m³/h), synthetic raw water temperature (26 ± 1ºC), coagulation pH (6.5 ± 0.1); flocculation time (17.2 minutes), the speed gradient flocculation (110 s-1); flow disposal after flocculation (0.8 m³/h), input flow to the flotation (Qe) (4, 6 m³/h), input speed for flotation (ve) (180 m/h), cross-flow velocity (45 m/h), TASzs (14.6 ± 0.2 m/h), saturation pressure (4.5 ± 0.1 kgf/cm ²). The pilot plant was fed with synthetic water, which showed turbidity of approximately 7.4 ± 0.6 NTU, and apparent color, about 39.4 ± 4.3 HU. The removal efficiency of the analyzed parameters for each Gzc is less sensitive to variations in the A/V in the configuration A than in the configuration B. In configuration A, the grille that showed Gzc about 6.5 s-1 gave better results for each A/V analysis. In configuration B, the grille that has generated Gzc around 4.7 s-1 provided the best removal efficiency of turbidity and color for each A/V studied. Furthermore, in the configuration B, the removal efficiency of color and turbidity was less sensitive to variations in A/V for Gzc 4.7 s-1 than for other values of Gzc. The grille that generated the best results in the configuration A was the same for the configuration B. Therefore the use of that grille favored the performance of configurations A and B. Comparing all the situations studied in two configurations, the test with the configuration A (with tzc the 54 s) with Gzc of 6.3 s-1 and A/V of 4.9 g/m³, had the highest removal efficiencies of color and turbidity.
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Bailey, Jonathan Pqul. "Development of shear wave velocity profiles in the deep sediments of the Mississippi Embayment using surface wave and spectral ratio methods." Diss., Columbia, Mo. : University of Missouri-Columbia, 2008. http://hdl.handle.net/10355/5635.
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Thesis (M.S.)--University of Missouri-Columbia, 2008.The entire dissertation/thesis text is included in the research.pdf file; the official abstract appears in the short.pdf file (which also appears in the research.pdf); a non-technical general description, or public abstract, appears in the public.pdf file. Title from title screen of research.pdf file (viewed on August 10, 2009 Includes bibliographical references.
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Green, Robert George. "The structure and seismicity of Icelandic rifts." Thesis, University of Cambridge, 2016. https://www.repository.cam.ac.uk/handle/1810/263564.
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Three-fifths of the Earth’s crust has been built at oceanic spreading centres in the last 160 million years. To explore crustal extension processes and the architecture of these constructive plate boundaries I have studied the oceanic rift in Iceland. Here the Mid Atlantic Ridge is anomalously elevated above sea level and thus easier to instrument. I have deployed and operated a dense network of seismometers in the remote volcanic highlands in central Iceland, and used the passive seismic data collected from this network to explore crustal structure and volcanic processes in the extensional rift zones. My analysis of persistent seismicity located in an intervening region between individual spreading segments, uniquely records the segmentation of plate spreading on the scale of individual volcanic systems. Precise location and characterisation of micro-earthquakes identifies a series of faults subparallel to the rift fabric, and source mechanisms define left-lateral strike-slip motion on these faults. This extremely high quality microseismic data reveals transform motion being accommodated by bookshelf faulting in a concentrated region between two such volcanic systems, providing evidence for the localisation of spreading in the discrete volcanic systems. While transform motion between spreading centres appears to be accommodated on a continuous basis, the extension of the brittle upper crust within the spreading centres occurs episodically during rifting events. Our local seismic network fortuitously recorded such a rifting episode in August 2014, during which the opening of a 5 metre wide dyke triggered a huge increase in seismicity across large areas of the rift zone. Stress-seismicity-rate modelling of this triggered seismicity, along with geodetic constraints on the deformation, provided a remarkable opportunity with which it was possible to prove the existence of stress-shadowing, a challenge which has eluded earthquake seismologists for decades. Using the excellent coverage of our extended seismic network I have also generated a new high resolution image of the regional crustal seismic structure using surface waves extracted from ambient seismic noise. The structure reveals low seismic velocities which are closely correlated with the volcanic rift zones, and faster wavespeeds in the older and non-volcanically active Tertiary crust. The strongest anomalies are seen in the north-west of the Vatnajökull icecap, at the location of thickest crust and inferred centre of the underlying mantle plume. Inversion for shear wave velocity structure shows high velocity-gradients in the top 10 km, defining a thickened extrusive upper crust in Iceland compared to standard oceanic crust, where it is normally 2–3 km thick. Below this, the shear wave velocity structure reveals a distinct low-velocity zone in the mid crust between 14–20 km depth, which is widespread across Iceland and shallows into the active volcanic rifts. This extensive feature suggests high mid-crustal temperatures and a high temperature-gradient between the extrusives of the upper crust and the intrusive mid-to-lower crust in Iceland.
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Stefansson, Gudmundur, Frederick Hearty, Paul Robertson, Suvrath Mahadevan, Tyler Anderson, Eric Levi, Chad Bender, et al. "A VERSATILE TECHNIQUE TO ENABLE SUB-MILLI-KELVIN INSTRUMENT STABILITY FOR PRECISE RADIAL VELOCITY MEASUREMENTS: TESTS WITH THE HABITABLE-ZONE PLANET FINDER." IOP PUBLISHING LTD, 2016. http://hdl.handle.net/10150/622681.
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Insufficient instrument thermomechanical stability is one of the many roadblocks for achieving 10 cm s(-1) Doppler radial velocity precision, the precision needed to detect Earth-twins orbiting solar-type stars. Highly temperature and pressure stabilized spectrographs allow us to better calibrate out instrumental drifts, thereby helping in distinguishing instrumental noise from astrophysical stellar signals. We present the design and performance of the Environmental Control System (ECS) for the Habitable-zone Planet Finder (HPF), a high-resolution (R = 50,000) fiber-fed near-infrared (NIR) spectrograph for the 10 m Hobby-Eberly Telescope at McDonald Observatory. HPF will operate at 180 K, driven by the choice of an H2RG NIR detector array with a 1.7 mu m cutoff. This ECS has demonstrated 0.6 mK rms stability over 15 days at both 180 and 300 K, and maintained high-quality vacuum (< 10 (7) Torr) over months, during long-term stability tests conducted without a planned passive thermal enclosure surrounding the vacuum chamber. This control scheme is versatile and can be applied as a blueprint to stabilize future NIR and optical high-precision Doppler instruments over a wide temperature range from similar to 77 K to elevated room temperatures. A similar ECS is being implemented to stabilize NEID, the NASA/NSF NN-EXPLORE spectrograph for the 3.5 m WIYN telescope at Kitt Peak, operating at 300 K. A [full SolidWorks 3D-CAD model] and a comprehensive parts list of the HPF ECS are included with this manuscript to facilitate the adaptation of this versatile environmental control scheme in the broader astronomical community.
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Fu, Li. "Rhéologie des polymères dans les contacts confinés : tribologie des interfaces étudiées par un nouveau dispositif couplant FRAPP et nanotribologie." Thesis, Strasbourg, 2015. http://www.theses.fr/2015STRAE030/document.
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Ce travail porte sur le développement d’une nouvelle technique expérimentale dédiée à l’étude de la rhéologie mise en jeux lors du glissement d’une pointe rigide sur une surface de polymère. Ce travail s'est déroulé progressivement de l'échelle mésoscopique vers l'échelle nanométrique. Pour cette dernière, la zone ciblée est la zone interfaciale confinée et cisaillée.Pour mettre en évidence les comportements de la zone cohésive, nous avons étudié un système de réseaux interpénétrés de polymères (RIPs) CR39-PMMA. Grâce à leurs propriétés ajustables, nous pourrons utiliser les RIPs sont utilisés comme substrat pour étudier la zone interfaciale en variant facilement les paramètres rhéologiques.Pour étudier les propriétés de la zone interfaciale, des couches phospholipidiques de DSPC ont été choisies comme matériau modèle. Leurs structures ont été étudiées par la réflectivité spéculaire de neutron. Nous montrons que la structure des couches supportées de DSPC est robuste, et le taux d’humidité́ relative joue un rôle important sur la structure. Les essais de glissement sur des couches de DSPC ont permis de relever les influences des paramètres mécaniques et environnementaux sur la contrainte de cisaillement Le développement du NanoTribo-FRAPP permet de caractériser le cisaillement des couches de DSPC sur une lame de verre, tout en mesurant la vitesse d’écoulement locale des couches moléculaires nanométriques. Nous pouvons ainsi estimer les plans de glissement en fonction de la vitesseThis work deals with the development of a new experimental technique and its application to study the rheology of a highly confined and sheared interfacial zone involved in the sliding of a rigid tip on a polymer suface. This tribological work has been conducted gradually from the mesoscopic scale to the nanoscale.To highlight the behavior of the cohesive zone, we studied an interpenetrating polymer network system (INPs) CR39-PMMA. Thanks to their adjustable properties, we may use the INPs as a substrate to study the interfacial zone by easily varying the rheological parameters.To study the rheological properties in the interfacial zone, the phospholipid layers of DSPC have been chosen as model material. The structures have been studied by the neutron reflectivity experiments. We show that the structure of supported layers of DSPC is robust, and the relative humidity plays a key role on it. Sliding tests on the DSPC layers reveals the influences of mechanical and environmental parameters on the shear stress. The development of NanoTribo-FRAPP allows to characterize the shear conditions of DSPC layers, with the measurements of local velocity of these of nanoscale molecular layers. This gives us access to estimate the slip planes as a function of imposed velocity
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Jervis, Anthony James. "Characterisation and mapping of stacking velocity and time effects of calcite-cemented zones, Cooper and Eromanga Basins /." Title page, abstract and contents only, 2001. http://web4.library.adelaide.edu.au/theses/09SB/09sbj57.pdf.
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Kaskar, Khalied. "Evaluation of quantitative motility and zona pellucida binding of human spermatozoa in an assisted reproductive programme." University of the Western Cape, 1994. http://hdl.handle.net/11394/8416.
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>Magister Scientiae - MScMale factor disorders affect more than 30% of infertile couples. Thus, it has become important to perform a andrological consultation and a basic semen evaluation in all male partners of couples consulting for infertility. The advent and development of assisted reproductive technologies has not only improved clinical results but also enhanced our basic understanding of the physiology of sperm and sperm preparation methods. Assisted reproduction has become among the more successful therapeutic modalities for a wide variety of sperm function disorders e.g. artificial insemination and in vitro fertilization (IVF) (Acosta et al. 1989). It is clear from recent experience that patients with male infertility showing oligozoospermia, asthenozoospermia, teratozoospermia (sometimes in combination), male immunological factor (antisperm antibodies) or ejaculatory problems as well as congenital abnormalities, can be successfully treated with IVF and embryo transfer. Prerequisite pre-fertilization changes by sperm, termed "capacitation" (Austin 1952) provides sperm with the capacity to fertilize eggs. These processes are generally regarded as encompassing all pre-fertilization changes occurring in sperm up 'to, but not including, loss of the acrosome (Bedford 1970). The endpoints of capacitation are often described as the acrosomal loss as well as changes in the motion characteristics. Capacitation alters the pattern of motility exhibited by freely swimming sperm, changing from a fairly rigid flagellar beat pattern to one of extreme flexure, often associated with increased thrust (Johnson et al. 1981) , which is referred to as hyperactivated motility (Yanagimachi 1981). without the transition to hyperactivated motility, sperm are unable to penetrate the zona pellucida (Fraser 1981), and possibly unable to fertilize eggs. Hyperactivation per se is marked by increased curvature in swimming trajectories and/or increased lateral displacement of the sperm head along their path (Burkman 1984). However, the physiological role of this change in motility is not clearly understood because almost all relevant data have been obtained under in vitro conditions. The association of specific seminal characteristics (sperm concentration, percentage motile cells and percentage normal sperm morphology) with the success rate of assisted particular has been The analysis of 1984; the reproductive techniques and IVF in under great scrutiny (Mahadevan and Trounson relationships between conventional semen parameters and fertilization rates in vitro has shown that sperm motility, concentration and morphology must be considered in estimating opportunities for successful intervention, as in the case of IVF and gamete intrafallopian transfer (GIFT) (Oehninger and Hodgen 1991). A reduction in the percentage of progressive motility alone does not seem to have a significant impact on IVF results unless it is below a threshold value of 10%. The semen sample should have an acceptable sperm concentration and morphology and/or that at least 1.5 X 106 motile spermatozoa can be recovered after swim-up separation (Acosta et al. 1989).
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El-Nahas, Waleed Mahmoud. "Effects of heating, breathing, hair style, posture, and air velocity on breathing zone concentrations for an anthropometrically-correct manikin in a wind tunnel." Morgantown, W. Va. : [West Virginia University Libraries], 2005. https://eidr.wvu.edu/etd/documentdata.eTD?documentid=4274.
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Thesis (Ph. D.)--West Virginia University, 2005.Title from document title page. Document formatted into pages; contains xiv, 256 p. : ill. (some col.). Includes abstract. Includes bibliographical references (p. 118-122).
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Schmelzbach, Cedric. "Seismic-Reflection and Seismic-Refraction Imaging of the South Portuguese Zone Fold-and-Thrust Belt." Doctoral thesis, Uppsala universitet, Geofysik, 2007. http://urn.kb.se/resolve?urn=urn:nbn:se:uu:diva-8302.
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The South Portuguese Zone (SPZ), which host world-class massive sulphide deposits, forms the southern fold-and-thrust belt of the Iberian Variscan orogeny. This thesis focuses on seismic-reflection and seismic-refraction processing efforts on a subset of the IBERSEIS deep seismic-reflection data set aiming at resolving the SPZ upper crust in high resolution. A comparison of different crooked-line seismic-reflection imaging schemes showed that a processing sequence involving dip-moveout corrections, a common-midpoint projection, and poststack time migration of common-offset gathers provided the most coherent images considering the crooked acquisition geometry. Correlation with surface-geological data allows four units of different reflection character to be identified: the ~0–2 km deep Upper Carboniferous Flysch group, the highly reflective ~2–4 km thick and up to ~5 km deep Volcano-Sedimentary Complex (VSC) group, and two deep Paleozoic metasedimentary units, with the shallower Phyllite-Quartzite group exposed in an antiform. Prominent diffracted energy was enhanced using a modified Kirchhoff imaging routine. High reflectivity and distinct diffractions mark extensive dike bands at 6–12 km depth, possibly related to the intense hydrothermal activity that led to the formation of the ore-bearing VSC group. Source-generated noise obscures potential signals from depths shallower than ~500m depth on the seismic-reflection sections. P- and SV-wave first-arrival traveltimes were inverted for velocity models imaging the shallowest crust. Overall, the velocity models correlate well with surface-geological data marking high (>5.25 km/s) and uniform P-velocities for the Flysch unit in the southern SPZ. A prominent P-wave low-velocity body (~4.5 km/s) is resolved where the Phyllite-Quartzite unit forms the core of an antiform. P-velocities fluctuate the most in the northern SPZ with Flysch group units exhibiting high velocities (>5.25 km/s) and VSC group bodies showing intermediate velocities (~5 km/s). Low VP/VS-ratios (~1.8) computed for the southern profile part are interpreted as less deformed Flysch-group units, whereas high VP/VS-ratios (~1.9) indicate fractured units.
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Persson, Emil, and Marcus Andersson. "Elitbandyspelares rörelseprofiler i förhållande till olika spelarpositioner." Thesis, Högskolan i Gävle, Avdelningen för hälso- och vårdvetenskap, 2015. http://urn.kb.se/resolve?urn=urn:nbn:se:hig:diva-19771.
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Inledning: Bandy är en vinterlagsport som innehåller både fysiska och tekniska krav. Till författarnas kännedom finns begränsat med vetenskaplig forskning om bandyspelares fysiska krav under match. Syfte: Syftet med denna studie var att beskriva manliga elitbandyspelares rörelseprofiler utifrån total distans, maximal hastighet, medelhastighet, speltid, hastighetszoner och acceleration under matchsituation mellan olika spelarpositioner. Metod: Datainsamlingen utfördes med tio hertz GPS-enheter på ett elitserielag i bandy från mellersta Sverige under säsongen 2014/15. Sex till åtta manliga elitbandyspelare studerades under elva matchtillfällen. Data analyserades både deskriptivt och genom envägs variansanalys (ANOVA) för att se signifikanta skillnader mellan spelarpositioner. Resultat: Mätningarna visade att spelarpositionen halv uppnådde den längsta totala distansen. Anfall hade den högsta medelhastigheten och utförde flest antal accelerationer per spelad minut. Spelarpositionen libero, back och halv hade den högsta speltiden och det var signifikanta skillnader till mittfält och anfall. Libero och back hade i de två långsammaste hastighetszonerna högst procent av total distans och utförde flest antal aktioner. Halv, mittfält och anfall hade i de två snabbaste hastighetszonerna högst procent av total distans och utförde flest antal aktioner. Slutsats: Detta indikerade att halv, mittfält och anfall hade likande resultat och hade de största fysiska kraven under match jämfört mot libero och back.Introduction: Bandy is a team winter sport that contains both physical and technical demands. To the authors knowledge there is a limited scientific research on bandy player’s physical demands during the matches. The Aim: The aim of this study was to describe the male elite bandy players movement profiles based on total distance, maximum velocity, mean velocity, game time, velocity zones and acceleration during the match between different playing positions. Method: Data was collected with ten hertz GPS-units in an elite league team in bandy from middle of Sweden during the season 2014/15. Six to eight male elite bandy players were examined during eleven matches. Data were analyzed both descriptive and with one-way analysis of variance (ANOVA) to see significant differences between playing positions. Results: The measurements showed that the playing position half preformed the longest total distance. Forward preformed the highest mean velocity and performed the most number of accelerations per played minute. The playing positions libero, back and half had the highest game time and had significant differences to midfield and forward. Libero and back had the highest percent of the total distance, and performed the highest number of efforts in the two slowest velocity zones. Half, midfield and forward had the highest percent of the total distance and performed the highest number of efforts in the two fastest velocity zones. Conclusion: This indicated that half, midfield and forward had similar results and had the highest physical demands during the game compared to libero and back.
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Ozer, Ceren. "Tsunami Hydrodynamics In Coastal Zones." Phd thesis, METU, 2012. http://etd.lib.metu.edu.tr/upload/12614343/index.pdf.
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This study analyzes the parameter &ldquohydrodynamic demand&rdquo
that is also defined by the square of Froude Number representing the damage of tsunami waves on structures and coastlines, and other hydrodynamic parameters, i.e., the distribution of instantaneous flow depths, runup values and the direction of maximum currents, occurred during tsunami inundation by using advanced numerical modeling. The analyses are performed on regular-shaped basins with different bottom slopes and real-shaped topographies using different wave shapes, wave periods and types. Various orientation and amount of coastal and land structures are used in simulations to have results for many different cases. This study provides the opportunity to define the damage of level in residential areas and to test the performance of coastal protection structures. The behavior of tsunami hydrodynamic parameters in shallow and inundation zone is investigated and a correlation is obtained between the average maximum values of square of Froude Number with the wave characteristics and sea bottom slope. After determining hydrodynamic parameters in regular shaped basins, a case study is applied by modeling the March 11, 2011 Great East Japan Tsunami with finer resolution in nested domains. The determination of hydrodynamic parameters in inundation zone during 2011 Japan event is performed in one of the most damaged coastal city Kamaishi.
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Preston, Leiph Alexander. "Simultaneous inversion of 3D velocity structure, hypocenter locations, and reflector geometry in Cascadia /." Thesis, Connect to this title online; UW restricted, 2003. http://hdl.handle.net/1773/6816.
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Liao, Tianfei. "Post processing of cone penetration data for assessing seismic ground hazards, with application to the New Madrid seismic zone." Diss., Available online, Georgia Institute of Technology, 2005, 2005. http://etd.gatech.edu/theses/available/etd-05042005-133640/.
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Thesis (Ph. D.)--Civil and Environmental Engineering, Georgia Institute of Technology, 2006.Mayne, Paul W., Committee Chair ; Goldsman, David, Committee Member ; Lai, James, Committee Member ; Rix, Glenn J., Committee Member ; Santamarina, J. Carlos, Committee Member.
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Hilairet, Nadège. "Rôle des serpentines dans la dynamique des zones de subduction : approche expérimentale à Haute Pression et Haute Température." Lyon, École normale supérieure (sciences), 2007. http://www.theses.fr/2007ENSL0429.
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Les serpentines, résultant de l'hydratation des minéraux mantelliques, pourraient être acteur majeur dans le transport de l'eau dans le manteau terrestre. Ayant une faible viscosité elle pourraient jouer un rôle déterminant dans la déformation et la répartition des contraintes dans les zones de subduction. Les équations d'état P-V des trois principales variétés de serpentines, lizardite, chrysotile et antigorite ont été obtenues expérimentalement. Une loi de déformation a été extraite d'expériences de déformation sur l'antigorite à HP-HT (200°C-500°C et 1à 4 GPa) et faible vitesse de déformation , réalisées sur synchroton avec une presse D-DiA. Les résultats expérimentaux permettent de discuter i) de la dynamique du coin de manteau dans la zone de subduction, ii) du rôle des serpentines dans la sismicité, et la relaxation inter-sismique et post-sismique.
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Wells, Anne, and Anne Wells. "Analysis of Off-axis, Low-velocity Zones on the Flanks of the Endeavour Segment of the Juan de Fuca Ridge." Thesis, University of Oregon, 2012. http://hdl.handle.net/1794/12319.
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Seismic data from the intermediate-spreading Endeavour segment of the Juan de Fuca Ridge reveal several crustal-level, low-velocity, high-attenuation regions on the eastern and western ridge flanks 7 to 16 km from the neovolcanic zone. I examine Pg amplitude anomalies for a wide variety of source-receiver azimuths in the Endeavour active source seismic tomography data. I use finite difference waveform forward modeling to estimate the dimensions, depth, and seismic properties of the best-observed inferred anomalous regions. The attenuating regions extend 10-15 km beneath axis-parallel bathymetric highs and from 2 to 4 km below the seafloor. The velocity reduction is small (~8%) and the attenuation large (QP ≈ 8-40) suggesting the presence of partial melt. I infer that melt focusing toward the neovolcanic zone is incomplete and that tectonic interactions with the Heckle seamount chain and/or the large segment-bounding overlapping spreading centers may promote off-axis melt delivery at the Endeavour segment.
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Cabrerizo, Sinca Julián. "Anàlisi quantitatiu de la velocitat dels vehicles a motor participants en atropellaments en zona urbana : modelització de la sensibilitat de la variable evitabilitat a les variacions de la velocitat específica del vehicle i de la velocitat màxima permesa de la via." Doctoral thesis, Universitat Politècnica de Catalunya, 2017. http://hdl.handle.net/10803/458374.
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Road traffic accidents lead to a number of significant problems, which are clearly reflected in the social costs (injuries, repercussions, deaths, etc.) and economic costs (prevention, healthcare, lost profits, etc.).
This search analyses the road traffic accidents involving pedestrians occurring in urban areas in order to extract conclusions on their causes, as well as the conditions of the road, people and vehicles involved.
The main goal is focused on a quantitative analysis of the influence had by motor vehicle speed in urban areas and how a change to the specific speed of the vehicle and/or the maximum speed limit influence the preventability of the accident itself.
Achieving this goal is based on four stages, which are defined as secondary objectives but which also contribute significant value within the search.
1) Historic report on how mobility and accident rates have undergone various changes over time and in different scenarios. 2) Presentation of the knowledge held by a professional community - road traffic accident reconstruction experts - for its inclusion in the scientific debate. The data have been extracted (collected, deduced, calculated, etc.) using techniques inherent to the discipline, and listing and cataloguing them is essential to this search. 3) Design of a database containing all the significant variables allowing them to be inter-related for analysis of a road traffic accident.
At most, this includes up to 250 records per case, distributed among highly distinct categories. 4) Categoric definition of the ¿preventability¿ concept, an essential variable in the road traffic accident reconstruction discipline. The concept of ¿preventability¿ in the field of this study is defined as the endogenous potential of the subject driver to avoid contact between a mechanical traction vehicle and a pedestrian exposed to the risk stemming from interaction between: a) the relative positions and prior speed of the pedestrian and vehicle; b) the perceptive and reactive capacity of the driver; and c) the surrounding environmental circumstances. Determining these significant variables enables the design of a preventability algorithm and preventability indices based on the maximum speed limit and the initial speed of the vehicle.
Achieving the secondary objectives culminates in statistical models that can explain aspects related to the concept of preventability and its sensitivity to the speed involved in road traffic accidents involving pedestrians. Preventability modelling has been measured for three variables, i.e.: preventability, the preventability/vehicle speed index, and the preventability speed/maximum speed limit index.
Six fundamental variables have been used to explain measurements relating to preventability: initial vehicle movement speed, maximum speed limit, risk exposure time of the pedestrian, maximum preventability speed, pedestrian movement speed and driver reaction time.
The statistical models chosen depend on the type of variable to be explained: a logistic regression model has been used for the preventability variable (this being a dichotomous variable (0/1)) that allows the effect of each explanatory variable on the response variable (preventability) to be explained.
In contrast, multiple linear regression models have been used for the preventability indices because these are capable of modelling continuous numeric variables in the response.
The main contribution from the search is focused on modelling the influence had by motor vehicle speed in urban areas and how a change to the speed might influence the preventability of the accident itself. Modelling the sensitivity of preventability to speed, whether the initial movement speed or maximum speed limit.La problemàtica de l'accidentalitat de transit té una importància rellevant: els costos socials (ferits, seqüeles, morts, etc.) i econòmics (prevenció, sanitaris, lucre cessant, etc.), així ho justifiquen. En aquesta recerca s'analitza els atropellaments produïts en entorns urbans per extreure conclusions relatives a les causes, circumstàncies de la via i de les persones i vehicles implicats. L'objectiu principal esta central en l’anàlisi quantitatiu de la influencia de la velocitat deis vehicles a motor en zona urbana i de com una variació de la velocitat específica del vehicle i/o de la velocitat màxima permesa, influeixen l'evitabilitat del propi accident. La consecució de l'objectiu, es desenvolupa en base a quatre etapes establertes com objectius secundaris, però que també són contribucions de vàlua significativa dins de la recerca efectuada . 1) Informe històric de com la mobilitat i l'accidentalitat han experimentat diverses mutacions cronològiques ien escenaris diferenciats. 2) Presentació del coneixement d'una comunitat professional -els reconstructors d'accidents de transit- per a la seva introducció al debat científic. L'extracció de dades (recollides, deduïdes, calculades, etc.) ha estat efectuada utilitzant tècniques pròpies de la disciplina i per desenvolupar aquesta recerca resulta imprescindible enumerar-les i catalogar-les. 3) Disseny d'una base de dades que conté toles les variables significatives i permet relacionar-les per analitzar un accident de transit. La versió maximalista ascendeix fins a uns 250 registres per cas , distribuïts per categories ben diferenciades. 4) Definició categòrica del concepte "Evitabilitat', variable fonamental en la disciplina de la Reconstrucció d'accidents. El concepte "Evitabilitat" a l’àmbit d'aquest estudi, esta definit com la potencialitat endògena del subjecte conductor, per eludir el contacte entre un vehicle de tracció mecànica i un vianant exposat al risc, que es deriva de la interacció entre :a) Les posicions relatives i velocitat prèvies de vianant i vehicle. b) La capacitat perceptiva i reactiva del conductor. c) Les circumstancies ambientals de l'entorn. La determinació de les variables significatives, habilita el disseny de l'algoritme de l'evitabilitar i els índexs d'evitabilitat en funció de velocitat màxima permesa i de la velocitat inicial del vehicle. La consecució deis objectius secundari, culminen en models estadístics que expliquen aspectes relacionats amb el concepte de l'evitabilitat i la seva sensibilitat a la velocitat deis atropellaments . La modelització de l'evitabilitat s'ha mesurat per tres variables que són: l'evitabilitat , l'índex d'evitabilitat a velocitat del vehicle i l'índex de la velocitat d'evitabilitat a velocitat màxima permesa. Per explicar les mesures relatives a l'evitabilitat, s'han utilitzat 6 variables fonamentals: velocitat de circulació Inicial del vehicle ; velocitat màxima permesa; temps d'exposició risc del vianant; velocitat màxima d'evitabilitat; velocitat desplaçament del vianant i temps de reacció del conductor. El models estadístics utilitzats depenen del tipus de variable a explicar: per la variable evitabilitat, al ser de tipus dicotòmic (0/1), s'ha utilitzat un model de regressió logística que permet explicar l'efecte que té cadascuna de les variables explicatives sobre la variable resposta (evitabilitat).En canvi, pels índex d'evitabilitat, s'han utilitzat models de regressió lineal múltiple, capaços de modelitzar variables numèriques contínues. La recerca, esta centrada en la modelització de la influencia de la velocitat deis vehicles a motor en zona urbana i de com una variació de la velocitat influeix en l'evitabilitat de l'accident. Modelitzem la sensibilitat de l'evitabilitat a la velocitat, ja sigui la velocitat de circulació Inicial o la màxima permesa.
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Audibert, Clément. "Contribution à la caractérisation des mécanismes dissipatifs sous sollicitation d'impact de structures composites sandwichs intégrant des fibres naturelles. Proposition d'une zone d'absorption pour siège pilote." Thesis, Chasseneuil-du-Poitou, Ecole nationale supérieure de mécanique et d'aérotechnique, 2017. http://www.theses.fr/2017ESMA0030/document.
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Ce travail s’inscrit dans la problématique de réduction de masse, de sécurité inhérent au domaine aéronautique, il concerne plus spécifiquement les sièges de pilotes d’avion de ligne. Un nouveau concept d’assise composite sandwich multifonctionnel est proposé. Il est composé d’une peau carbone, d’une âme nid d’abeille Nomex et d’une peau hybride Kevlar/lin. L’assemblage de plusieurs matériaux engendre des comportements parfois complexes et rend difficile la prédiction de la ruine de la structure. Une démarche expérimental/numérique est mise en place pour appréhender l’endommagement de l’assise et ainsi permettre un pré-dimensionnement via un outil numérique.Tout d’abord, des essais de caractérisation permettent d’élaborer les lois de comportement des différents matériaux constituant le sandwich. Le composite hybride présente un comportement élasto-plastique-endommageable-anisotrope. Le nida Nomex est représenté par un réseau de ressort et une loi couplant le comportement en compression et en cisaillement qui est implémentée dans ABAQUS. Des essais d’impacts permettent d’évaluer les modes de rupture et l’énergie dissipée par les concepts d’assises réalisés. Des simulations numériques intégrant les comportements matériaux identifiés sont mises en places pour corréler l’essai d’impact. L’analyse couplée des résultats expérimentaux et numériques permet d’identifier les couplages entre les différents mécanismes. Enfin, le modèle est utilisé pour dimensionner une assise composite qui s’avère sans optimisation fine, comparable à une assise existante en aluminium de l’A350This work is part of the problem of mass reduction, safety inherent in the aeronautical field, it concerns more specifically the seats of pilots of airliner. A new multi-functional sandwich composite seat pan is proposed, composed by a carbon skin, a Nomex honeycomb core and a Kevlar/flax hybrid skin. The assembly of several materials generates complex behaviors and makes the ruin of the structure difficult to predict. An experimental/numerical approach is used to understand the damage mechanism of the seat and to create a pre-dimensioning numerical tool.Firstly, characterization tests allow identifying the mechanical behaviors of each material and constituting a database for the creation of material laws. The hybrid composite shows an elastoplastic-damaging-anisotropic behavior. The honeycomb is represented by a spring network and a law coupling the compression and shear behavior is implemented. Impact tests are used to evaluate the failure modes and the energy dissipated by the different concepts. The impact tests are correlates by numerical simulation using the identified material behaviors. The analysis of the experimental and numerical results makes it possible to identify the coupling between the different mechanisms. Finally, the model is used to design a new composite seat pan. This one is comparable to the existing aluminum seat pan without optimization phase
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Matonti, Christophe. "Exploration géophysique des processus de fracturation et de réactivation dans les carbonates à l'échelle métrique." Thesis, Aix-Marseille, 2015. http://www.theses.fr/2015AIXM4744.
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Le but de ce travail est de comprendre les relations entre la déformation et la diagenèse dans les carbonates. Pour cela, l’échelle du m au dam est adéquate car elle permet de séparer les effets matriciels, des fractures et des failles. Celle-ci est sous la résolution de la sismique, donc peu de données géophysiques et diagénétiques spatiale et quantitatives sont disponibles, le plus souvent limitées aux données 1D de puit.Nous avons choisi 4 affleurements présentant des hétérogénéités et des intensités de déformation et de diagenèse diverses. Un protocole multi-échelle et multidisciplinaire a été développé, comprenant de la géophysique à l’échelle du cm au dam, de la diagenèse structurale et de la géochimie sur les ciments de fracture. Nous montrons un fort effet d’échelle entre les Vp en laboratoire et à l’affleurement dû à des hétérogénéités sédimentaire, d’enfouissement et structurale, qui conduisent à différents motifs géostatistiques.Les fractures ont l’effet le plus fort sur les Vp, modulé par leur cimentation, et qui peut entièrement effacer la signature initiale du faciès. La réactivation des fractures induit une anisotropie directionnelle de 10% due à des changements dans le remplissage des fractures, caractérisés par de multiples phases de cimentation, broyage et dissolution.Dans les zones de faille, l’anisotropie sismique est amplifiée, conduisant à un fort affaiblissement de la roche au cisaillement et à une diminution de Vp autour de la faille. Les données géochimiques tracent plusieurs flux de fluides diagénétiques et soulignent les fortes interactions entre l’évolution de la perméabilité, la diagenèse structurale et la signature géophysique des carbonatesThe aim of this work was to understand the relationships between deformations and diagenesis in carbonates. The relevant scale to study it may be the m to dkm scale which allows individualizing fracture, fault and matrix effects. This scale is under the seismic resolution, so few quantitative diagenetic and geophysical spatial data are available, mainly constrained to 1D borehole.Therefore, we selected 4 dkm scale outcrops displaying various heterogeneities and intensities of deformation and diagenesis. We developed a multidisciplinary/multiscale protocol including geophysics from cm to dkm scale along with structural diagenesis study and geochemical measurements on fractures cements. We found a strong scale effect between laboratory and outcrop Vp due to sedimentary, burial and structural heterogeneities that lead to different geostatistical patterns. Fractures have the strongest effect on Vp, being modulated by their cementation and can erase the initial facies acoustic signature. The fracture reactivation induce a 10% Vp directional anisotropy due to microscale changes in the fractures infillings characterized by multiple cementation, crushing and dissolution phases. In fault-zones the seismic anisotropy magnitude is amplified, leading to a strong directional rock shear weakening and a Vp decrease around the fault, caused by higher discontinuities aperture and brecciation. Geochemical data indicate that the Vp signature evolution is linked to different diagenetic fluids flow origins occurring during each deformation phase. This underlines the strong interplay between permeability evolution, structural diagenesis and geophysical signature in carbonates
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Tanikawa, Wataru. "Transport properties and high-velocity frictional behavior of Chelungpu, Shuangtung and Shuichangliu fault zones and their implication for fault motion during 1999 Chi-Chi earthquake." 京都大学 (Kyoto University), 2006. http://hdl.handle.net/2433/144202.
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Kyoto University (京都大学)0048
新制・課程博士
博士(理学)
甲第12119号
理博第3013号
新制||理||1449(附属図書館)
23955
UT51-2006-J114
京都大学大学院理学研究科地球惑星科学専攻
(主査)教授 嶋本 利彦, 助教授 田上 高広, 教授 平島 崇男
学位規則第4条第1項該当
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Nugroho, Hendro. "GPS Velocity Field In The Transition From Subduction To Collision Of The Eastern Sunda And Banda Arcs, Indonesia." Diss., CLICK HERE for online access, 2005. http://contentdm.lib.byu.edu/ETD/image/etd885.pdf.
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Seclaman, Alexandra Catalina. "Chemical and physical behaviour of the trace elements in the silicate melts of the Earth's mantle." Thesis, Lyon, 2016. http://www.theses.fr/2016LYSEN004/document.
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Nous avons étudié des magmas ferrifères silicatés magnésiens à la pression du manteau terrestre en utilisant la dynamique moléculaire (First Principles Molecular Dynamics). Les résultats de l’équation d’état que nous avons obtenus à partir de nos simulations ont été utilisés pour créer un modèle chimique et minéralogique pour les zones de très basse vitesse sismique (ULVZ, anomalies régionales dans le manteau proche de la limite noyau-manteau). De plus, nous avons étudié le comportement du Ni, du Co et du Fe dans ces magmas et établi la dépendance du spin en fonction de la concentration, de la pression, de la température et du degré de polymérisation du magma silicaté. Nous avons montré qu’une baisse du spin moyen peut être corrélée au changement de pente (kink) observé précédemment pour les coefficients de partage du Ni et du Co. Nous avons analysé la structure du magma pour toutes les compositions étudiées en fonction de la pression. Nos résultats donnent un nouvel aperçu de la coordination des éléments majeurs et traces dans les magmas silicatés de différents degrés de polymérisation. Nous interprétons l’anomalie de coordination Ni-O en fonction de la pression comme un changement d’état de spin. L’effet de la polymérisation du magma silicaté sur les coefficients de partage du Co, du Ni et du W entre le métal et le magma silicaté a été étudié par expériences multi-enclumes en conditions isobares et isothermes. Nous avons réalisé des simulations FPMD de magmas à des degrés de polymérisation similaires aux expériences afin d’expliquer le caractère de plus en plus lithophile du W lorsque le degré de polymérisation du magma silicaté diminue. Nous proposons une explication structurale pour expliquer l’affinité décroissante apparente du W dans les magmas silicatés dépolymérisésWe explore Fe-bearing Mg-silicate melts through the pressure regime of the Earth’s mantle using First Principles Molecular Dynamics (FPMD). The equation of state results we obtained from our simulations are used to create a chemical and mineralogical model for Ultra-Low Velocity Zones (anomalous region on the mantle side of the core-mantle boundary). Furthermore we study the behaviour of Ni, Co, and Fe in these melts, and asses their spin-crossover dependencies on their concentration, pressure, temperature, and the degree of polymerization of the silicate melts. We show that a decrease in the average spin can be correlated with the previously observed kink in the partitioning coefficient of Ni and Co. We investigate the melt structure of all the compositions studied as a function of pressure. Our results provide new insight into the coordination of major and trace elements in silicate melts with different degrees of polymerization. We interpret the anomalous Ni-O coordination trend with pressure as the result of the spin state change. The effect of silicate melt polymerization on the partitioning of Co, Ni, and W between a metal and silicate melt, is investigated at isobaric and isothermic conditions using multi-anvil experiments. We have performed FPMD simulations of melts with similar degrees of polymerization as the experiments in order to explain the increasing lithophile character of W with the decrease in polymerization of the silicate melt. We propose a structural explanation for tungsten’s apparent increased affinity for depolymerized silicate melts
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Moruzzi, Rodrigo Braga. "Avaliação da influência da distribuição de tamanho de partículas e do binômio velocidade/tempo de detenção na zona de reação no desempenho da flotação com emprego de sonda ultra-sônica e de técnica de análise por imagem." Universidade de São Paulo, 2005. http://www.teses.usp.br/teses/disponiveis/18/18138/tde-04072007-170028/.
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O desempenho de uma unidade de flotação por ar dissolvido (FAD) em escala piloto, tratando água destinada ao abastecimento contendo 50 uC e 05 uT, foi investigada sob o ponto de vista das partículas presentes (micro-bolhas e flocos) e da hidrodinâmica. A análise centrou-se na zona de reação da unidade de FAD onde foi desenvolvido o modelo matemático proposto por Reali (1991). A determinação das partículas foi realizada por método que emprega a análise de imagem. A condição hidrodinâmica foi avaliada por meio de ensaios de estímulo e resposta, combinada com a análise tridimensional do escoamento feita através de mapeamento utilizando equipamento que emprega ultra-som (sonda micro-ADV). Para a consecução do trabalho foram desenvolvidos dois métodos. Um para aquisição, tratamento e obtenção da distribuição de tamanho de micro-bolhas e flocos utilizando a análise de imagem digital em instalação com escoamento contínuo, sem a extração de amostras. Outro, envolvendo o desenvolvimento de programa (VelDigital3D) para tratamento dos dados da sonda utilizada. Inicialmente, foram realizados os ensaios de validação da utilização da sonda micro-ADV em água contendo micro-bolhas de ar e os ensaios de mapeamento da unidade utilizando a referida sonda conjugada ao programa VelDigital3D. Posteriormente, foram investigados alguns possíveis agentes na aglutinação das micro-bolhas após a despressurização tais como: i) as condições de mistura expressas em termos da taxa de aplicação superficial (TAS) e tempo de detenção na zona de reação (Tdz.r), ii) razão de recirculação (p), iii) a variação de pH e, iv) a dosagem de coagulante (\'AL POT.+3\'). Finalmente, a sensibilidade do modelo matemático proposto por Reali (1991) para a zona de reação de unidades de FAD convencional foi verificada com base nos parâmetros de projeto: tempo de detenção da zona de reação (Tdz.r) e taxa de aplicação superficial na zona de clarificação TASap. (downflow); e com base nos parâmetros operacionais: distribuição de tamanho de partículas (micro-bolhas e flocos) e razão de recirculação (p). As principais conclusões foram: i) a sonda micro-ADV pode ser utilizada para obtenção do perfil de velocidade em águas contendo micro-bolhas de ar, nas vazões investigadas; ii) o escoamento no interior da zona de reação apresentou um padrão bem definido de recirculação ao longo da altura, confirmando os resultados obtidos com os ensaios estímulo e resposta; iii) a variação do diâmetro médio das micro-bolhas foi muito pequena (de 20 a 30 \'mü\'m), embora tenha havido ressalvas e iv) o modelo proposto por Reali (1991) foi sensível aos parâmetros investigados e responde coerentemente com o desempenho da unidade piloto de FAD.This work investigated the performance of a dissolved air flotation (DAF) pilot plant, used to treat drinking water containing 05 Tu and 50 Cu. The particles (micro-bubbles and flocs) and hydraulic characteristics were taken into account. The focus was given in the reaction zone as hypothesized by Reali\'s mathematic model (REALI, 1991). An image analyses was used to assess particles distribution sizes. The hydraulics of the DAF tank was assessed by using a pulse stimulus-response test combined with the three-dimensional flow analyses carried-out with equipment that applied ultra sound (microADV). Therefore, two methods were developed; one for the acquisition, treatment and also to obtain the micro-bubbles and flocs sizes distribution, without the need of extracting samples and another, involved the development of a software (VelDigital3D) in order to treat the microADV data. Initially, the application of the microADV in the DAF process was evaluated. After, the data collection was made and the result was treated by using the VelDigital3D software. Sequentially, the effects of some agents for micro-bubbles coalescence after the releasing point were investigated: i) mixture conditions in terms of hydraulic loading rate (HLR) and detention time (DT); ii) recirculation rate (p); iii) pH variation and, iv) coagulant dosage (\'AL POT.+3\'). Finally, the mathematic model behavior proposed by Reali (1991) was investigated by varying some parameters in the design, such as: detention time in the reaction zone (DTr.z) and hydraulic loading rate in the clarification zone HLRc.z (dowflow); and by varying some operational parameters, such as: particles sizes distribution (micro-bubbles and flocs) and recirculation rate (p). The main conclusions were: i) the microADV probe can be used to obtain the velocity flow profile in water containing micro-bubbles; ii) the flow within the reaction zone showed a well defined pattern of recirculation throughout the height of the unit, confirming the obtained results by using the stimulus-response tests; iii) the variation of micro-bubbles medium size was low (from 20 to 30 \'mü\'m) but some points regarding this aspect were discussed and, iv) the behavior of the mathematical model proposed by Reali (1991) showed a significant adjustment to the experimental data proving that it can be applied to analyzed design parameters.
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Galybin, Konstantin A. "P-wave velocity model for the southwest of the Yilgarn Craton, Western Australia and its relation to the local geology and seismicity." University of Western Australia. School of Earth and Geographical Sciences, 2007. http://theses.library.uwa.edu.au/adt-WU2007.0167.
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[Truncated abstract] A number of controlled and natural seismic sources are utilised to model the Pwave velocity structure of the southwest of the Yilgarn Craton, Western Australia. The Yilgarn Craton is one of the largest pieces of Archaean crust in the world and is known for its gold and nickel deposits in the east and intraplate seismicity in the west. The aim of the project is to link 2D and 3D models of variations in seismic velocity with the local seismicity and geology. A new set of seismic refraction data, acquired in 25 overlapping deployments between 2002 and 2005, has been processed, picked and analysed using forward modelling. The data comprise two perpendicular traverses of three-component recordings of various delay-fired blasts from local commercial quarries. The data were processed using a variety of techniques. Tests were carried out on a number of data enhancement and picking procedures in order to determine the best method for enhancement of delay-fired data. A new method for automatic phase recognition is presented, where the maximum of the derivative of the rectilinearity of a trace is taken as the first break. Complete shot gathers with first break picks for each seismic source are compiled from the overlapping deployments. ... The starting 3D model was based on the models produced by 2D forward modelling. 14 iterations were carried out and the best-fit 3D model was achieved at the 10th iteration. It is 35% better then the current model used to locate earthquakes in this region. The resultant velocity block model was used to iii construct a density block model. A relative gravity map of the southwest of Yilgarn Craton was made. The results of 2D forward modelling, 3D tomography and forward gravity modelling have been compared and it was found that the HVZ is present in all models. Such a zone has been previously seen on a single seismic refraction profile, but it is the first time, this zone has been mapped in 3D. The gravity high produced by the zone coincides with the gravity high observed in reality. There is strong evidence that suggests that the HVZ forms part of the Archaean terrane boundary within the Yilgarn Craton. The distribution of the local seismicity was then discussed in the framework of the new 3D velocity model. A hypothesis, that the primary control on the seismicity in the study area is rotation of the major horizontal stress orientation, is presented. It is also argued that the secondary control on seismicity in the SWSZ is accommodation of movements along major faults.
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Freitas, Damien. "The transport properties of Earth’s upper mantle materials : insights from in situ HP-HT experiments." Thesis, Université Clermont Auvergne (2017-2020), 2019. http://www.theses.fr/2019CLFAC058.
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Les propriétés de transport des roches mantelliques sont des paramètres importants pour interpréter aussi bien qualitativement que quantitativement les informations géophysiques, telles que la vitesse des ondes sismiques, les flux de chaleurs et les profils magnétotelluriques terrestres. L’origine des anomalies géophysiques du manteau supérieur, comme la zone de faible vitesse (LVZ ; 70-150km de profondeur) et le niveau de faible vitesse (LVL ; 350-410 km de profondeur), est peu renseignée et demande des contraintes expérimentales. Au cours de cette thèse, nous avons étudié les propriétés électriques, sismiques et thermiques des péridotites solides et partiellement fondues via le développement de techniques géophysiques in situ. Nos expériences à hautes pressions et températures, en presse multi-enclumes, nous ont permis d’établir les effets de la fusion sur ces différentes propriétés physiques aux conditions mantelliques. Nous avons, pour la première fois, réalisé des mesures combinées de conductivité électrique et de vitesses des ondes sismiques en une seule et même expérience. Grâce à cette technique, nous avons réconcilié les mesures du taux de fusion impliquées dans la LVZ estimées par les deux signaux géophysiques avec 0.3-0.8%vol de fusion partielle. L’équilibre textural entre les phases liquides et solides s’est révélé être fondamental pour la comparaison des mesures en laboratoire. Nous avons ensuite procédé à la première reproduction de fusion par déshydratation durant l’ascension des péridotites hydratées depuis la zone de transition mantellique vers le manteau supérieur (entre 12 et 14 GPa). Au cours de la fusion partielle, les signaux sismiques et électriques mesurés sont comparables aux observations géophysiques confirmant l’hypothèse de fusion au niveau de la LVL. Les taux de liquides impliqués à la base du manteau supérieur seraient alors modestes (< 2 %vol). La composition des magmas produits précise le rôle de filtre chimique de ce niveau situé entre les manteaux supérieur et profond. La densité estimée du magma confirme sa flottabilité neutre, favorisant la stabilité de ce niveau au cours des temps géologiques. Les analyses des éléments volatils et les modélisations des transferts d’hydrogène prouvent que ce niveau est un réservoir potentiel d’eau profond et favorise l’hypothèse d’une hydratation par la base du manteau supérieur. Enfin, des méthodes de mesure de diffusivité thermique (Angström, pulse) ont été adaptées à la presse multi-enclumes du LMV. Des procédures de traitement et des modélisations des transferts thermiques ont été développées Les premières mesures de diffusivité thermique de verres et liquides réalistes aux conditions mantelliques ont pu ainsi être réalisées. De plus, la caractérisation d’échantillons aux structures variées a pu être effectuée à l’aide de la méthode Angström (périclase, olivine, péridotite partiellement fondue)The transport properties of mantle rocks are key parameters to qualitatively and quantitatively interpret direct and indirect geophysical information such as seismic velocities, heat fluxes and electromagnetic profiles across Earth’s and planetary interiors. The origins of upper mantle geophysical anomalies such as the Low Velocity Zone (70-150 km deep) and the Low Velocity Layer (350-410 km deep) are poorly known and require experimental constraints. In this PhD thesis, we have explored the electrical, seismic and thermal properties of realistic solid and partially molten peridotites via the development of geophysical in situ techniques. Performed at high pressures and temperatures in multi-anvil apparatus, our experiments allowed the characterization of the effect of melting on these different physical properties at mantle conditions. We performed the first experimental combination of electrical conductivity and sound wave velocity in a single multi-anvil experiment. Thanks to this technique, we reconciled electrical and seismic estimations of the melt fraction implied in the LVZ with 0.3-0.8 Vol.% of partial melting. The textural equilibration between melt and solid phases was found to be crucial for the comparison of laboratory estimations. We then realized the first reproduction of the dehydration melting process during the ascend of hydrous peridotites from the mantle transition zone to the upper mantle, between 12 and 14 GPa. Measurements during partial melting gave acoustic and electrical signals comparable to geophysical observations favoring partial melting explanation of the LVL anomaly. The implied melt fractions at upper mantle base were quantified to be moderate (<2 Vol.%). The chemical composition of produced melts confirmed the role of chemical filter of this melt layer located between upper and deep mantle. The calculated density confirmed the neutral buoyancy of the melt layer, making it a stable feature over geological times. Volatiles analyses and hydrogen transfer modeling confirmed this layer as a potential deep water reservoir and favored a bottom-up hydration of Earth’s upper mantle. Thermal diffusivity characterization techniques (Angström and pulse heating methods) were adapted to the LMV multi-anvil apparatus. Improved treatment procedures were elaborated for thermal transfer characterization under HP and HT conditions. The first thermal diffusivity characterization of glasses and melts at realistic mantle conditions were performed. In addition, thermal diffusivities of various samples (periclase, olivine, peridotite) were investigated with different structures (solid, solid+melt etc.) using Angström method
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Ben, Ali Neji. "Caractérisation et modélisation micromécanique de la propagation de fissures fragiles par effet de l'hydrogène dans les alliages AA 7xxx." Phd thesis, Ecole Nationale Supérieure des Mines de Saint-Etienne, 2011. http://tel.archives-ouvertes.fr/tel-00648428.
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Nous étudions la fragilisation par l'hydrogène de l'alliage d'aluminium 7108. Une technique expérimentale spécifique a été développée : Un pré-chargement en hydrogène des échantillons, à travers un dépôt de nickel de quelques dizaines de microns, qui empêche la dissolution du substrat d'aluminium, est utilisé. Il permet la comparaison de la résistance à la fragilisation de différentes microstructures modèles. Nous étudions l'effet du traitement thermique et de la précipitation sur la sensibilité à l'hydrogène pour des vitesses de déformation macroscopiques imposées variables. Différents modes de rupture sont observés ainsi que des transitions entre eux. Au moyen de simulations numériques à l'échelle mésoscopique, l'effet de taille des précipités intergranulaires pré-fragilisés sur la ténacité des joints de grains est estimé, en utilisant un modèle de zone cohésive. Nous analysons la compétition entre la diffusion de l'hydrogène vers la pointe de la fissure et la vitesse de fissuration par un couplage mécanique - diffusion basé sur la diffusion de l'hydrogène assistée par la contrainte hydrostatique. Une vitesse critique au-delà de laquelle l'hydrogène ne peut plus suivre la fissure, est mise en évidence. L'influence de la microstructure du joint de grains sur cette vitesse est analysée. La valeur est comparée à une estimation des vitesses de propagation expérimentales obtenues pour différentes vitesses de déformation macroscopiques. Nous analysons l'effet du piégeage de l'hydrogène par les précipités intergranulaires et la désorption sur la répartition de l'hydrogène le long du joint de grains en imposant un flux au niveau de l'interface précipités - matrice.
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Franken, Thijs. "Analysing partial melting in the Réunion mantle plume." Thesis, Université de Paris (2019-....), 2019. http://www.theses.fr/2019UNIP7129.
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La fusion partielle dans la partie supérieure du manteau est fréquente dans les zones de remontée d’eau du manteau, comme les rifts, les dorsales médio-océaniques et les points chauds. Des zones de faible vitesse d’ondes de cisaillement dans le manteau peu profond (∼ 80 km) sont souvent associées à ces endroits, révélant des anomalies de vitesse de 4 à 5 % généralement attribuées à la présence de matériau fondu. Cependant, les études sur la quantité de matière fondue responsable de la réduction de la vitesse conduisent, suivant leur nature, à des conclusions différentes: les résultats expérimentaux de la pétrologie, des observations géochimiques et des modèles géodynamiques suggèrent une rétention de la matière fondue inférieure à 1 %, alors que les interprétations sismiques exigent une rétention supérieure à 1%. Dans cette thèse, j’essaie de résoudre le désaccord sur la rétention de la masse fondue dans l’asthénosphère en croisant des modèles de production de matériau en fusion et de propagation des ondes sismiques pour relier directement les conditions géodynamiques de la fusion partielle aux observations sismiques du panache mantellique de la Réunion. J’ai mis au point un modèle 1D de production de fusion qui évalue la rétention de la matière fondue selon le coefficient de perméabilité, la températures initiale du manteau et la vitesses de remontée d’eau selon un problème de Stokes modifié supposant un écoulement poreux. 210 scénarios de modèles de fusion sont convertis en vitesses d’ondes P et S sismiques anharmoniques à l’aide d’une base de données de paramètres minéraux, qui sont ensuite incorporés dans le modèle de référence de la terre ak135 pour générer des sismogrammes synthétiques des scénarios de fusion pour 21 tremblements de Terre. J’analyse l’effet du matériau fondu sur les composantes radiale, transversale et verticale de l’onde pour les arrivées de phase P, S, Pdiff et SKS. Grâce à une procédure automatisée de corrélation croisée, je calcule les différences relatives de temps de parcours entre les sismogrammes observés et les 210 traces synthétiques, pour chacun des 21 événements, 4 arrivées de phase, 3 composantes d’onde et 4 fréquences différentes de filtrage. J’analyse 70 896 points de données de temps de parcours relatifs pour trouver une solution optimale rendant compte des temps de parcours relatifs entre les traces du modèle et les observations sismiques, afin de découvrir quel scénario de fusion décrit le manteau supérieur sous la Réunion. La solution au scénario du modèle le mieux adapté n’est pas unique, puisque plusieurs combinaisons du coefficient de perméabilité, de température et de vitesse de remontée peuvent donner la même solution. En analysant séparément la distribution des paramètres du modèle sur la solution de temps de parcours relatif minimisé des 70 896 points de données pour les différentes arrivées de phase et composantes des ondes, on peut identifier deux régimes probables des conditions du manteau supérieur pouvant rendre compte des observations sismiques. Les conditions de manteau sous la Réunion se situent soit dans la plage de température de 1300 à 1350°C avec des fractions en fusion de ∼ 1 %, soit dans la plage de température de 1400 à 1450 °C avec des fractions en fusion inférieures à 0,3 %. Les contraintes des études sur la température du manteau supérieur, la perméabilité et les vitesses de transport du matériau fondu correspondent à ce dernier cas, ce qui souligne qu’une faible rétention de matériau fondu dans le manteau peu profond sous la Réunion satisfait simultanément les observations sismiques et les conditions géodynamiques prévuesPartial melting in the upper mantle is prevalent in areas of mantle upwelling such as rifts, mid-ocean ridges and hotspots. The presence of low shear-wave velocity zones in the shallow mantle (∼ 80km) are often associated with these locations, revealing velocity anomalies of −4 to −5% which are generally attributed to the presence of melt. However, studies on the quantity of melt responsible for the velocity reduction are divided, where experimental results from petrology, geochemical observations and geodynamical models suggest melt retention of < 1%, whereas seismic interpretations call for 1 > %. In this thesis I attempt to resolve the disagreement on melt retention in the asthenosphere by combining forward modelling of melt production and seismic wave propagation to relate geodynamic condition of partial melting directly to seismic observations of the Réunion mantle plume. I developed a 1D model of melt production that approximates melt retention for a range of permeability coefficients, initial mantle temperatures and upwelling velocities through a set of modified Stokes equations assuming porous flow. 210 melting model scenarios are converted to anharmonic seismic P- and S-wave velocities using a mineral parameter database, which are embedded into the ak135 earth reference model to generate synthetic seismograms of the melting scenarios for 21 source events using the Direct Solution Method for a laterally homogeneous and spherically symmetrical Earth. I explore the effect of melt presence on the radial, transverse and vertical wave component for the P, S, Pdiff and SKS phase arrivals, band-pass filtered to upper corner frequencies of 0.05, 0.1, 0.15 and 0.2 Hz. Through an automated cross-correlation procedure I compute relative traveltime differences between the observed seismograms and the 210 synthetic model traces for each iteration of the 21 source events, 4 phase arrivals, 3 wave components, and 4 band-pass filter frequencies. I analyse 70,896 relative traveltime datapoints to reach a solution for the minimised relative traveltimes between the model traces and the seismic observations, in order to discover which melting model scenario describes the upper mantle beneath Réunion. The solution to the best-fit model scenario is non-unique, since several combinations of the permeability coefficient, temperature and upwelling velocity give the same solution. By seperately analysing the parameter distribution of the free model parameters over the minimised relative traveltime solution of the 70,896 datapoints for the different phase arrivals and wave components, two likely regimes of upper mantle conditions can be constrained that can resolve the seismic observations. These regimes indicate that mantle conditions beneath Réunion are either in the 1300−1350 °C temperature range with melt fractions of ∼ 1%, or in the 1400−1450 °C temperature range with melt fractions of < 0.3%. Constraints from studies on upper mantle temperature, permeability and melt transportation velocities correspond to the latter case, showing that low retention of melt in the shallow mantle beneath Réunion simultaneously satisfy seismic observations and the expected geodynamic conditions
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Meca, Karen Soraia. "Influência do tempo de detenção hidráulica e do gradiente médio de velocidade na zona de contato no desempenho de unidade piloto de flotação por ar dissolvido aplicado à clarificação de água para abastecimento." Universidade de São Paulo, 2014. http://www.teses.usp.br/teses/disponiveis/18/18138/tde-14112017-104621/.
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O desempenho de unidades de flotação por ar dissolvido (FAD) depende significativamente do projeto da zona de contato (ZC) dessas unidades, situada na entrada das mesmas e responsável por promover condições adequadas para que ocorram taxas satisfatórias de colisão entre as microbolhas de ar e os flocos formados na etapa antecedente de floculação da água para abastecimento. Os dois principais parâmetros de projeto da ZC são o tempo de detenção hidráulico ou tempo de contato (Tzc) e o gradiente médio de velocidade na ZC (Gzc). A presente dissertação apresenta os resultados de estudo sobre a influência do Tzc e do Gzc na ZC de uma unidade piloto de flotação por ar dissolvido (UPFAD) com escoamento contínuo aplicada ao tratamento de água para abastecimento. Foram utilizados módulos contendo tela metálica em seu interior com malha de #25 mm com diferentes dimensões, de modo a se obterem diferentes valores de Gzc e Tzc. Foram investigadas duas configurações na unidade de FAD (Configurações A e B), nas quais o comprimento (Lzc) e a altura (Hzc) da ZC foram variados, permitindo a alteração do Tzc e mantendo-se controlados os valores de Gzc (com a introdução ou não de diferentes módulos de tela metálica na ZC) e vice versa. Os demais parâmetros do processo de FAD não sofreram variações, tais como taxa de aplicação superficial (TAS) na zona de separação, tempo de floculação, entre outros. Para a configuração A, foram estudadas três alturas diferentes na ZC e para a configuração B, quatro alturas diferentes na ZC, o que acarretou, para cada valor de Gzc variação do Tzc. Para cada configuração da ZC, também foram testados três valores de vazão de recirculação de água saturada com ar de modo a se obterem três diferentes concentrações de ar (A/V) no processo de flotação. Para todos os parâmetros analisados (Turbidez, Cor, Absorbância), as maiores eficiências de remoção foram obtidas nos ensaios realizados com o uso da tela #25 mm tanto na configuração A (TASzc = 136 m/h e G = 6,1 s-1) quanto na configuração B (TASzc = 87 m/h e G = 3,2 s-1). Os resultados permitem concluir que o par de valores (Tzc, Gzc) é mais apropriado para o projeto da zona de contato de unidades FAD do que o par (Tzc, TASzc) usualmente adotado pelos projetistas, sendo que, na faixa de valores investigados a UPFAD apresentou melhor desempenho para o par: Tzc de 41 s e Gzc de 6,1 s-1.The performance of units dissolved air flotation (DAF) depend significantly of design on the contact zone (CZ) of these units, situated at the entrance thereof and responsible for promoting appropriate conditions to occur satisfactory collision rates between air microbubbles and the flocs formed in the step of flocculation of potable water. The two main design parameters of the CZ are the hydraulic detention time or contact time (Tcz) and the velocity gradient in the CZ (Gcz). This work presents the results of study of the effects of varying the Tcz and Gcz at the contact zone of pilot unit DAF with continuous flow applied to the treatment of potable water. Were used modules containing metal grille with mesh of #25 mm, with different dimensions in order to obtain different values of Gcz and Tcz. Were investigated two configurations in the unit FAD ( configurations A and B) where the length (Lcz) and height (Hcz) of contact zone were varied, allowing the variation of Tzc and keeping the values of Gcz controlled (with the introduction or not of different modules in the metal grille in CZ) and vice versa, without changes in other process variables FAD, such as rate of surface application (TAS) in the separation zone, flocculation time, among others. For the configuration A were studied three different heights in the CZ and in configuration B, four different heights in the CZ, which resulted, for each value of Gcz (relative to the chosen value of Lcz) the variation of Tzc. For each configuration of CZ were also tested three values of recirculation flow of air saturated in order to obtain three different values of concentration in air (A/V) in the flotation process. For all parameters analyzed (turbidity, color, absorbance), the highest efficiencies were obtained in assays performed using the grille #25 mm, both in configuration A (TAScz = 136 m/h and L = 6,1 s-1) and configuration B (TAScz = 87 m/h and G = 3,2 s-1). The results indicate that the pair of values (Tcz, Gcz) is more suitable for project of the CZ of units FAD than the pair (Tcz, TAScz) usually adopted by the designers, and values in the range investigated in UPFAD showed performed better for Tcz of 41 s and Gcz of 6,1 s-1.
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Guérin, Frédéric. "Emission de gaz à effet de serre (CO2,CH4) par une retenue de barrage hydroélectrique en zone tropicale (Petit-saut, Guyane française) : expérimentation et modélisation." Toulouse 3, 2006. https://tel.archives-ouvertes.fr/tel-00079947.
Full textAbstract:
Les émissions de dioxyde de carbone (CO2) et de méthane (CH4) et le cycle du carbone dans la retenue de barrage de Petit-Saut et la rivière Sinnamary (Guyane Française) ont été étudiés dans le but de développer un modèle couplé hydrodynamique-biogéochimie. Le développement de ce modèle a nécessité l'étude de trois processus contrôlant ces émissions : (i) la production de CO2 et de CH4 lors de la dégradation de la matière organique (MO) des sols et de végétaux, (ii) l'oxydation aérobie du CH4 dans la colonne d'eau du barrage et (iii) les processus d'échange gazeux à l'interface air-eau. Sur 10 ans, les émissions atmosphériques se sont avérées très significatives, notamment les trois premières années ayant suivies la mise en eau, puis décroissent au cours du temps. Tandis que 50% des émissions de CO2 ont lieu à la surface du lac, les émissions de CH4 sont principalement localisées en aval des turbines. Les émissions atmosphériques résultent de la dégradation de la MO (sol et biomasse issus de la forêt tropicale) immergée lors de la mise en eau et leur diminution au cours du temps découle de l'épuisement du stock de MO. Au terme de 10 ans, 20% du stock de carbone a été minéralisé et émis vers l'atmosphère sous forme de CO2 et de CH4. L'oxydation aérobie du CH4 transforme plus de 95% du CH4 diffusant depuis l'hypolimnion en CO2 dans la colonne d'eau du lac et 40% du CH4 entrant dans la rivière à l'aval. A l'échelle du barrage ce processus est responsable de l'oxydation de 90% du CH4 produit et de 30% des émissions totales de CO2. Le CH4 et le CO2 qui atteignent les eaux de surface du barrage sont émis vers l'atmosphère par flux diffusifs. L'étude de ce processus de transfert gazeux à l'interface air-eau montre que, en milieu tropical, les flux diffusifs sont accélérés par les fortes températures et les phénomènes pluvieux. Le modèle est basé sur le modèle hydrodynamique SYMPHONIE 2D et les modules biogéochimiques développés dans le cadre de cette étude à partir des données cinétiques des processus étudiés. Les profils verticaux simulés de température, d'oxygène, de CO2 et de CH4 sont bien reproduits. Ce modèle pose les bases d'un outil opérationnel de modélisation pour la retenue de Petit Saut ainsi que pour d'autres réservoirs en milieu tropicalThe emissions of carbon dioxide (CO2) and methane (CH4) and the carbon cycle in the Petit-Saut reservoir and in the Sinnamary River (French Guiana) were studied with an aim of developing a coupled physical/biogeochemical model. The development of this model required the study of three processes controlling these emissions: (i) CO2 and CH4 production during the mineralization in anoxic condition of organic matter (OM) from soils and plants, (ii) aerobic CH4 oxidation in the water column of the lake and (iii) the processes involved in gas exchange at the air-water interface. Over 10 years, atmospheric emissions were shown to be very significant, in particular the first three years having followed the reservoir impoundment and then decreased with time. While 50% of the CO2 emissions take place at the surface of the lake, the emissions of CH4 are mainly localized downstream from the turbines. The atmospheric emissions result from the degradation of OM (soil and biomass originating from the tropical forest) flooded during impoundment and their reduction with time rises from the exhaustion of the OM stock. 10 years after impoundement, 20% of the carbon stock were mineralized and emitted to the atmosphere in the form of CO2 and of CH4. Aerobic CH4 oxidation transforms more than 95% of the CH4 diffusing upward from the hypolimnion into CO2 in the water column of the lake and 40% of the CH4 entering the river downstream of the dam. In the whole Petit Saut system, this process is responsible for the oxidation of 90% of the produced CH4 and 30% of the total CO2 emissions. The CH4 and CO2 which reach the water surface of the reservoir and of the river downstream of the dam are emitted to the atmosphere by diffusive flux. The study of this process of gas transfer to the interface air-water shows that, in tropical environment, diffusive fluxes are enhanced by the elevated temperatures and the rainy phenomena. The model is based on the hydrodynamic model SYMPHONY 2D and the biogeochemical model developed during this study starting from the kinetic data of the studied processes. The simulated vertical profiles of temperature, oxygen, CO2 and CH4 are well reproduced. This model poses the bases of an operational tool of modeling for the Petit-Saut reservoir like for other reservoirs in tropical environments
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SIMON, GUY. "Dynamique de l'atmosphere solaire." Paris 7, 1987. http://www.theses.fr/1987PA077161.
Full textAbstract:
Analyse des structures (de bulles chromospheriques) qui montent dans la couronne a des vitesses de l'ordre de 50 km/s et des possibilites de transfert d'energie et de moment directement au vent solaire. Analyse d'observations simultanees dans deux raies spectrales pour comparer les flux de masse dans le soleil calme et dans les plages faculaires. Un modele d'arches est propose pour leur interpretation. La deuxieme partie concerne les transitoires coronaux, associes a l'ejection de matiere dans le vent solaire. Un scenario est propose pour l'origine de ces perturbations