Dissertations / Theses on the topic 'Receiver functions'
To see the other types of publications on this topic, follow the link: Receiver functions.
Create a spot-on reference in APA, MLA, Chicago, Harvard, and other styles
Consult the top 50 dissertations / theses for your research on the topic 'Receiver functions.'
Next to every source in the list of references, there is an 'Add to bibliography' button. Press on it, and we will generate automatically the bibliographic reference to the chosen work in the citation style you need: APA, MLA, Harvard, Chicago, Vancouver, etc.
You can also download the full text of the academic publication as pdf and read online its abstract whenever available in the metadata.
Browse dissertations / theses on a wide variety of disciplines and organise your bibliography correctly.
1
Lipke, Katrin, Frank Krüger, and Dirk Rößler. "Subduction zone structure along Sumatra from receiver functions." Universität Potsdam, 2008. http://opus.kobv.de/ubp/volltexte/2008/1826/.
Full textAbstract:
Receiver functions are a good tool to investigate the seismotectonic structure beneath the a seismic station. In this study we apply the method to stations situated on or near Sumatra to find constraints on a more detailed velocity model which should improve earthquake localisation. We estimate shallow Moho-depths (~ 21 km) close to the trench and depths of ~30 km at greater distances. First evidences for the dip direction of the slab of ~60° are provided.
Receiver functions were calculated for 20 stations for altogether 110 earthquakes in the distance range between 30° and 95° from the receiver. However the number of receiver functions per station is strongly variable as it depends on the installation date, the signal-to-noise-ratio of the station and the reliability of the acquisition.Receiver Funkttion stellen eine gut Methode zur Untersuchung von Seismotektonischen Strukturen unterhalb einer seismischen Station dar. In dieser Arbeit wenden wir die Methode auf Station auf oder nahe Sumatra an um Hinweise für ein detaillierteres Geschwindigkeitsmodell zu erhalten, welches die Lokalisierung von Erdbeben verbessern sollte. Wir ermitteln flache Moho-Tiefen (~21 km) in der Nähe des Trenchs und Tiefen um die 30 km in größeren Distanzen. Erste Hinweise für eine Einfallsrichtung des Slabs von ~60° konnten gefunden werden. Receiver Funktionen wurden für 20 Stationen für insgesamt 110 Erdbeben im Distanzbereich zwischen 30° und 95° berechnet. allerdings ist die Anzahl von Receiver Funktionen pro Station sehr variabel, da sie vom Installationszeitpunkt, dem Signal-Rausch-Verhältnis und der Zuverlässigkeit der Datenaufnahme an der Station abhängt.
2
Lombardi, Denis. "Alpine crustal and upper-mantle structure from receiver functions /." Zürich : ETH, 2007. http://e-collection.ethbib.ethz.ch/show?type=diss&nr=17508.
Full text
3
Morice, Stephen Patrick. "A receiver function study in the Peloponnese, Greece." Thesis, University of Cambridge, 1995. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.264508.
Full text
4
Ashoori, Pareshkoohi Azadeh. "Lithospheric Structure Across the Northern Canadian Cordillera from Teleseismic Receiver Functions." Thesis, Université d'Ottawa / University of Ottawa, 2016. http://hdl.handle.net/10393/35535.
Full textAbstract:
A major change in seismic velocities between Earth’s crust and mantle is known as the Mohorovicic discontinuity (Moho). The depth of the Moho plays an important role in characterizing the overall structure of the crust and can be related to the tectonic setting of a region. Teleseismic P-wave receiver function techniques can provide estimates of the depth of the Moho and therefore crustal thickness under a broadband station. In this research we are interested in the structure of the crust and mantle across the northern Canadian cordillera, described by various tectonic settings. The teleseismic data recorded by broadband three-component seismic stations are used to perform receiver function analysis to determine the lateral variations of Moho depth under northern Canadian cordillera and map out the crustal thickness under the broadband stations. Based on visual inspection of receiver function results in the region, we find evidence of anisotropy or dipping reflectors in the crustal structure of the northern cordillera observed in back-azimuthal variations of transverse component receiver functions. We further provide a quantitative interpretation of receiver function in terms of anisotropy or dipping structure by decomposing the azimuthal variations of depth migrated receiver functions into back-azimuthal harmonics. This technique can be used to map out the orientation of anisotropy that may be related to cracks and/or rock texture caused by deformation. We resolve the Moho at an average depth of ~35 km along the western profile of the study area. Harmonic decomposition along the study area yields crustal anisotropy at depth 5-20 km, which does not extend in the lower crust. This can be the result of complex deformation at a detachment zone like a quasi-rigid displacement of the upper crust over a lower crust. The detected anisotropy over the study area is not coherent as the slow symmetry directions detected by harmonic decomposition are highly variable.
5
Condori, Cristobal, George S. França, Hernando J. Tavera, Diogo F. Albuquerque, Brandon T. Bishop, and Susan L. Beck. "Crustal structure of north Peru from analysis of teleseismic receiver functions." PERGAMON-ELSEVIER SCIENCE LTD, 2017. http://hdl.handle.net/10150/625974.
Full textAbstract:
In this study, we present results from teleseismic receiver functions, in order to investigate the crustal thickness and Vp/Vs ratio beneath northern Peru. A total number of 981 receiver functions were analyzed, from data recorded by 28 broadband seismic stations from the Peruvian permanent seismic network, the regional temporary SisNort network and one CTBTO station. The Moho depth and average crustal Vp/Vs ratio were determined at each station using the H-k stacking technique to identify the arrival times of primary P to S conversion and crustal reverberations (PpPms, PpSs + PsPms). The results show that the Moho depth correlates well with the surface topography and varies significantly from west to east, showing a shallow depth of around 25 km near the coast, a maximum depth of 55-60 km beneath the Andean Cordillera, and a depth of 35-40 km further to the east in the Amazonian Basin. The bulk crustal Vp/Vs ratio ranges between 1.60 and 1.88 with the mean of 1.75. Higher values between 1.75 and 1.88 are found beneath the Eastern and Western Cordilleras, consistent with a mafic composition in the lower crust. In contrast values vary from 1.60 to 1.75 in the extreme flanks of the Eastern and Western Cordillera indicating a felsic composition. We find a positive relationship between crustal thickness, Vp/ Vs ratio, the Bouguer anomaly, and topography. These results are consistent with previous studies in other parts of Peru (central and southern regions) and provide the first crustal thickness estimates for the high cordillera in northern Peru.
6
Schuh, John Joseph. "Resolving Variations in the Tectonostratigraphic Terrane Structure of New England Using Receiver Functions." Thesis, Boston College, 2014. http://hdl.handle.net/2345/bc-ir:103557.
Full textAbstract:
Thesis advisor: John E. EbelPassive teleseismic data were collected with a 17-station broadband seismic array deployed from Vermont to Massachusetts. The purpose of the array was to detect changes in crustal seismic velocity structure related to the regional tectonostratigraphic terranes using receiver functions. Ps conversions from the Moho and mid-crust were observed and a cross-section of the crustal structure beneath the seismic array was produced. The crustal cross-section reveals a synclinal structure related to the Taconic orogeny, a remnant Iapetan oceanic slab, a plausible surface-location of the Red Indian Line, and several terrane boundaries that can be projected from their proposed surface locations into the deeper crust based on crustal-horizon offsets observed in the receiver function data
Thesis (MS) — Boston College, 2014
Submitted to: Boston College. Graduate School of Arts and Sciences
Discipline: Earth and Environmental Sciences
7
Sodoudi, Forough. "Lithospheric structure of the Aegean obtained from P and S receiver functions." [S.l.] : [s.n.], 2005. http://www.diss.fu-berlin.de/2005/241/index.html.
Full text
8
Sodoudi, Forough. "Lithospheric structure of the Aegean obtained from P and S receiver functions." Potsdam : Geoforschungszentrum [u.a.], 2006. http://deposit.d-nb.de/cgi-bin/dokserv?idn=978391810.
Full text
9
Porritt, R. W., and S. Yoshioka. "Evidence of Dynamic Crustal Deformation in Tohoku, Japan, From Time-Varying Receiver Functions." AMER GEOPHYSICAL UNION, 2017. http://hdl.handle.net/10150/626288.
Full textAbstract:
Temporal variation of crustal structure is key to our understanding of Earth processes on human timescales. Often, we expect that the most significant structural variations are caused by strong ground shaking associated with large earthquakes, and recent studies seem to confirm this. Here we test the possibility of using P receiver functions (PRF) to isolate structural variations over time. Synthetic receiver function tests indicate that structural variation could produce PRF changes on the same order of magnitude as random noise or contamination by local earthquakes. Nonetheless, we find significant variability in observed receiver functions over time at several stations located in northeastern Honshu. Immediately following the Tohoku-oki earthquake, we observe high PRF variation clustering spatially, especially in two regions near the beginning and end of the rupture plane. Due to the depth sensitivity of PRF and the timescales over which this variability is observed, we infer this effect is primarily due to fluid migration in volcanic regions and shear stress/strength reorganization. While the noise levels in PRF are high for this type of analysis, by sampling small data sets, the computational cost is lower than other methods, such as ambient noise, thereby making PRF a useful tool for estimating temporal variations in crustal structure.
10
Schneider, Felix Michael [Verfasser]. "Imaging an Intra-continental Subduction in Central Asia with Teleseismic Receiver Functions / Felix Michael Schneider." Berlin : Freie Universität Berlin, 2014. http://d-nb.info/1054341443/34.
Full text
11
Byrnes, Joseph. "Mantle flow and melting beneath young oceanic lithosphere: Seismic studies of the Galápagos Archipelago and the Juan de Fuca Plate." Thesis, University of Oregon, 2017. http://hdl.handle.net/1794/22638.
Full textAbstract:
In this dissertation, I use seismic imaging techniques to constrain the physical state of the upper mantle beneath regions of young oceanic lithosphere. Mantle convection is investigated beneath the Galápagos Archipelago and then beneath the Juan de Fuca (JdF) plate, with a focus on the JdF and Gorda Ridges before turning to the off-axis asthenosphere. In the Galápagos Archipelago, S-to-p receiver functions reveal a discontinuity in seismic velocity that is attributed to the dehydration of the upper mantle. The depth at which dehydration occurs is shown to be consistent with prior constraints on mantle temperature. A comparison between results from receiver functions, seismic tomography and petrology shows that mantle upwelling and melt generation occur shallower than the depth of the discontinuity, despite the expectation of high viscosities in the dehydrated layer. Beneath the JdF and Gorda Ridge, low Vs anomalies are too large to be explained by the cooling of the lithosphere and are attributed to partial melt. The asymmetry, large Vs gradients, and sinuosity of the anomalies beneath the JdF Ridge are consistent with models of buoyancy-driven upwelling. However, deformation zone processes appear to dominate mantle flow over seafloor spreading beneath the Explorer and Gorda diffuse plate boundaries. Finally, S-to-p receiver functions reveal a seismic discontinuity beneath the JdF plate that can only be attributed to seismic anisotropy. Synthesis of the receiver function results with prior SKS splitting results requires heterogeneous anisotropy between the crust and the discontinuity. Models of anisotropy feature increasing anisotropy before the decrease at the discontinuity, but well below the base of the lithosphere, and a clockwise rotation of the fast direction with increasing depth. In these results and even in the SKS splitting results, additional driving mechanisms for mantle flow such as density or pressure anomalies are required.
12
Gans, Christine. "Investigations of the Crust and Upper Mantle of Modern and Ancient Subduction Zones, using Pn Tomography and Seismic Receiver Functions." Diss., The University of Arizona, 2011. http://hdl.handle.net/10150/145719.
Full textAbstract:
Advances in seismology allow us to obtain "high-resolution" images of the Earth's subsurface. This dissertation summarizes the results of three seismic studies on three different continents, with the aim of better understanding the crust and upper mantle structure of seemingly disparate yet ultimately related regions. The seismic techniques of Pn tomography and P-wave receiver function (RF) analysis are applied to central Turkey (Pn tomography), western Argentina and southwestern Wyoming, USA (RF analysis). These studies look at both a present-day convergent margin (Andean subduction zone, Argentina) and two ancient ones (Bitlis-Zagros collision zone of Arabia-Africa with Eurasia, Turkey; Farallon subduction zone, Wyoming).Using Pn tomography, we were able to detect the limit of the slab rupture edge along the Central Anatolian Fault Zone, Turkey. Slab break-off is an important process that modifies the mantle in tectonically active regions, and the limit of the oceanic Arabian slab break-off along the Bitlis-Zagros Suture Zone, thought to have begun at 11 Ma, was previously undetermined.Using RF analysis, we obtained high-resolution images of the subducting slab beneath the Sierras Pampeanas, Argentina. Continental Moho contours roughly follow terrane boundaries, suggesting that ancient terranes continue to exert control over present-day continental deformation. Overthickened oceanic crust is often cited as a cause of flat slab subduction; our RF results indicate that the crust is moderately overthickened, around 11-16 km. Further, we image offsets in the RF arrivals that indicate the subducted slab is broken or offset in along trench-subparallel fractures.The crustal structure beneath southwestern Wyoming, the location of ancient Farallon flat slab subduction, was studied using RF analysis. Looking at regional crustal structure, results include a new depth to Moho map. Coherency of the seismic signal across the dense LaBarge array (55 stations, ~250 m spacing) was investigated, with results showing that complicated shallow structure can greatly impact the resulting RF signal. Modeling of RFs using synthetics helped to separate the complex signal containing multiple primary conversions and their reverberations, which interact constructively and destructively. The dense spacing of the LaBarge array allowed unique opportunities to investigate coherency of waveforms across very short distances.
13
Heuer, Barbara. "Lithospheric and upper mantle structure beneath the western Bohemian Massif obtained from teleseismic P and S receiver functions." Potsdam : Geoforschungszentrum [u.a.], 2006. http://www.diss.fu-berlin.de/2006/401/index.html.
Full text
14
Eulenfeld, Tom [Verfasser]. "Temporal Variations of Crustal Properties in Northern Chile Analyzed with Receiver Functions and Passive Image Interferometry / Tom Richter." Berlin : Freie Universität Berlin, 2014. http://d-nb.info/1048558606/34.
Full text
15
van, Manen Dirk-Jan. "Time-reversal and interferometry, with applications to forward modeling of wave propagation and a chapter on receiver functions." Thesis, University of Edinburgh, 2006. http://hdl.handle.net/1842/2563.
Full textAbstract:
In exploration seismics and non-destructive evaluation, acoustic, elastic and electro-magnetic waves sensitive to inhomogeneities in the medium under investigation are used to probe its interior. Waves multiply scattered by the inhomogeneities carry significant information but, due to their non-linear relation with the inhomogeneities, are notoriously dificult to image or invert for subsurface structure. Recently, however, this paradigm may have been broken as it was shown that high-order multiply scattered acoustic waves can be time-reversed and focused onto their original source location through arbitrary, unknown, inhomogeneous media using a so-called time-reversal mirror: in a first step, the multiply scattered waves are recorded on an array of transducers partially surrounding the medium, in the second step the recorded wavefields are time-reversed and reemitted into the medium (i.e., the time-reversal mirror acts as a linear boundary condition on the medium injecting the time-reversed, multiply scattered wave- field). The multiply scattered waves retrace their paths through the medium and focus on the original source location. In another development the full waveform Green's function between two (passive) receivers has been observed to emerge from crosscorrelation of multiply scattered coda waves. This process is called interferometry. The principal aim of this thesis is to explore the relation between time-reversal and interferometry and to apply the resulting insights to forward modelling of wave propagation in the broader context of inversion. A secondary aim is to see if the seismological receiver function method can be applied to a reflection setting in ways that are both dynamically and kinematically correct. These aims are achieved through: (1) Derivation of an integral representation for the time-reversed wavefield in arbitrary points of an inhomogeneous medium [first, for the acoustic case, based on the Kirchhoff-Helmholtz integral, then for the elastic case based on the Betti-Rayleigh reciprocity theorem]. Evaluation of these integral representations for points other than the original source point will be shown to give rise to the Green's function between the two points. Physically intuitive explanations will be given as to why this is the case. (2) Application of ordinary reciprocity to the integral representation for the time-reversed wavefield to get an expression in terms of sources on the surrounding surface only. This gives rise to an efficient and flexible forward modeling algorithm. By illuminating the medium from the surrounding surface and storing full waveforms in as many points in the interior as possible, full waveform Green's functions between arbitrary points in the volume can be computed by cross correlation and summation only. (3) Derivation of an exact, interferometric von Neumann type boundary condition for arbitrary interior perturbed scattering problems. The exact bound- ary condition correctly accounts for all orders of multiple scattering, both inside the scattering perturbation(s) and between the perturbations and the background model and thus includes all so-called higher-order, long-range interactions. (4) A comprehensive study of the receiver function method in a reflection setting, both kinematically and dynamically. All presented results are verified and illustrated by numerical (finite-difference) modelling. Overall, the results in this thesis demonstrate that, while the original instabilities associated with direct inversion remain, multiply scattered waves can be used in an industrial context { both in real-life experiments and in forward modelling { in ways that are stable. The presented advances in forward modelling are argued to have a significant impact on inversion as well, albeit indirectly.
16
Schneider, Felix Michael [Verfasser]. "Imaging an intra-continental subduction in Central Asia with teleseismic receiver functions / Felix Michael Schneider. Deutsches GeoForschungsZentrum GFZ." Potsdam : Deutsches GeoForschungsZentrum GFZ, 2014. http://nbn-resolving.de/urn:nbn:de:kobv:b103-14063.
Full text
17
Calkins, Josh A. "An Investigation of Lithospheric Structure and Evolution in Convergent Orogenic Systems using Seismic Receiver Functions and Surface Wave Analysis." Diss., The University of Arizona, 2008. http://hdl.handle.net/10150/195366.
Full textAbstract:
Whether by accretion, magmatic addition, or refinement of more mafic lithologies, continental arcs are likely zones for the creation of "average" continental crust with intermediate silica content. This dissertation contains the results of broadband seismic studies carried out in two field areas, an active subduction zone and the remnants of an extinct arc, with the aim of understanding lithospheric evolution at convergent margins. The analytical techniques of receiver function calculation and surface wave tomography are applied to data sets collected above the Andean subduction zone in Chile and western Argentina and in the Coast Mountains Batholith of central British Columbia. We present the first in-depth comparison of receiver functions calculated using the high frequencies available in records of intermediate-depth local earthquakes with those calculated from the lower frequency data in records of larger teleseismic events. The comparison reveals that the lower crust beneath the Western Sierras Pampeanas contains a gradational velocity increase over ~20km above a small velocity step at the Moho. Surface wave tomography confirms the existence of an unusually high velocity anomaly in the mantle above the slab and yields estimates of slab thickness on the order of 50 km. To the south of the flat slab region, we see evidence of active mantle wedge convection above the steep slab, but no evidence of the lithosphere-asthenosphere boundary beneath the subducting Nazca plate. In the Coast Mountains Batholith (CMB), receiver functions image a bright, continuous Moho throughout the study region. Combined with petrologic modeling, the receiver function data point toward convective removal of any ultramafic root that formed beneath the CMB. Low absolute shear wave velocities in the upper mantle resolved via surface wave analysis strengthen the case for root removal beneath the eastern section of the CMB. On the far western edge of the CMB, we find evidence of a partially reformed lithosphere outboard of a major tectonic boundary. These observations shed light on the distillation of felsic to intermediate continental crust from more mafic primary magmas in active subduction zones and the eventual return of the complementary ultramafic residuals to the convecting mantle.
18
Cossette, Élise. "Crustal Seismic Anisotropy and Structure from Textural and Seismic Investigations in the Cycladic Region, Greece." Thesis, Université d'Ottawa / University of Ottawa, 2015. http://hdl.handle.net/10393/32475.
Full textAbstract:
In the first article, the seismic properties for a suite of rocks along the West Cycladic Detachment System (Greece) are calculated, using Electron backscatter diffraction (EBSD) measurements and the minerals’ elastic stiffness tensors. Muscovite and glaucophane well defined crystallographic preferred orientation increases the seismic anisotropy. Maximum Pwave velocities have the same orientation as the Miocene extension and maximum S-wave anisotropy is subhorizontal, parallel with mineral alignment, suggesting strong radial anisotropy with a slow subvertical axis of symmetry. In the second article, teleseismic receiver functions are calculated for an array of stations in the Cyclades and decomposed into back-azimuth harmonics to visualise the variations in structure and anisotropy across the array. Synthetic receiver functions are modeled using the first order structural observations of seismic discontinuities and EBSD data. They indicate 5% of anisotropy with slow symmetry axis in the upper crust, and demonstrate the importance of rock textural constraints in seismic velocity profile interpretation.
19
Sodoudi, Forough [Verfasser]. "Lithospheric structure of the Aegean obtained from P and S receiver functions / Geoforschungszentrum Potsdam, Stiftung des Öffentlichen Rechts. Forough Sodoudi." Potsdam : Geoforschungszentrum, 2006. http://d-nb.info/978391810/34.
Full text
20
Marson-Pidgeon, Katrina Ann, and katrina marson-pidgeon@anu edu au. "Seismogram synthesis for teleseismic events with application to source and structural studies." The Australian National University. Research School of Earth Sciences, 2001. http://thesis.anu.edu.au./public/adt-ANU20010925.152548.
Full textAbstract:
The aim of this thesis is to develop procedures for the modelling and inversion of teleseismic P and S waveforms which are as flexible as possible. This flexibility is necessary in order to obtain accurate source depth and mechanism estimates for small to moderate size events, such as those that are relevant in the context of monitoring the Comprehensive Nuclear-Test-Ban Treaty (CTBT). ¶
The main challenge for extending source depth and mechanism inversion methods to smaller events is to ensure that sufficiently accurate synthetic seismograms are available for comparison with observed records. An accurate phase-adaptive reflectivity method has therefore been developed, against which the performance of less computationally intensive approximations can be judged. The standard reflectivity method has been modified to allow for different crustal and upper mantle structures at the source and receiver, and the full effects of reverberations and conversions in these structures can be allowed for. Core reflections and refractions can also be included; these phases can become important at certain distance ranges. A slowness bundle approach has been developed, where a restricted slowness integration about the geometric slowness for the direct wave is undertaken at each frequency, allowing accurate results to be obtained whilst avoiding the expense of a full reflectivity technique. ¶ Inversion using the neighbourhood algorithm (NA) is performed for source depth, mechanism and time function, by modelling direct P and S and their surface reflections (pP, sP and pS, sS) at teleseismic distances. Both SV and SH data are exploited in the inversion, in addition to P data, in order to obtain improved constraints on the source mechanism, including any isotropic component. Good results are obtained using a simple generalised ray scheme, however, the use of a flexible derivative-free inversion method means that more accurate synthetics are able to be used in the inversion where appropriate. The NA makes use of only the rank of the data misfits, so that it is possible to employ any suitable misfit criterion. In the few cases where control on the source mechanism is limited, good depth resolution is still usually obtained. ¶The structures near the source and receiver play an important role in shaping the detail of the teleseismic waveforms. Although reasonable results can be achieved with simple synthetics and a standard velocity model, significant improvement can be made by modifying the representation of structure near the source and receiver. In the case of sub-oceanic events it is important to allow for the effects of water reverberations. The crustal structure near the receiver can also have quite a large influence on the waveforms through reverberations and conversions. This is exploited in receiver function inversion, which is again accomplished using the NA approach.
21
Schoonman, Charlotte Maria. "Vertical motions at the fringes of the Icelandic plume." Thesis, University of Cambridge, 2017. https://www.repository.cam.ac.uk/handle/1810/267950.
Full textAbstract:
The Icelandic mantle plume has had a profound influence on the development of the North Atlantic region over its 64 Myr existence. Long-wavelength free-air gravity anomalies and full waveform tomographic studies suggest that the planform of the plume is highly irregular, with up to five fingers of hot asthenosphere radiating away from Iceland beneath the lithospheric plates. Two of these fingers extend beneath the British Isles and southern Scandinavia, where departures from crustal isostatic equilibrium and anomalous uplift have been identified. In this study, the spatial extent of present-day dynamic support associated with the Icelandic plume is investigated using receiver function analysis. Teleseismic events recorded at nine temporary and 59 permanent broadband, three-component seismometer stations are used to calculate 3864 P-to-S crustal receiver functions. The amplitude and arrival time of particular converted phases are assessed, and H-k stacking is applied to estimate bulk crustal properties. Sub-selections of receiver functions are jointly inverted with Rayleigh wave dispersion data to obtain crustal VS profiles at each station. Both inverse- and guided forward modelling techniques are employed, as well as a Bayesian, trans-dimensional algorithm. Moho depths thus obtained are combined with seismic wide-angle and deep reflection data to produce a comprehensive crustal thickness map of northwestern Europe. Moho depth is found to decrease from southeast (37 km) to northwest (26 km) in the British Isles and from northeast (46 km) to southwest (29 km) in Scandinavia, and does not positively correlate with surface elevation. Using an empirical relationship, crustal shear wave velocity profiles are converted to density profiles. Isostatic balances are then used to estimate residual topography at each station, taking into account these novel constraints on crustal density. Areas of significant residual topography are found in the northwestern British Isles (1400 m), southwestern Scandinavia (464 m) and Denmark (620 m), with convective support from the Icelandic plume as its most likely source. Finally, the irregular planform of the Icelandic plume is proposed to be a manifestation of radial viscous fingering due to a Saffman-Taylor instability. This fluid dynamical phenomenon occurs when less viscous fluid is injected into a layer of more viscous fluid. By comparing the thermal and convective characteristics of the plume with experimental and theoretical results, it is shown that viscous fingering could well explain the present-day distribution of plume material.
22
Heuer, Barbara [Verfasser]. "Lithospheric and upper mantle structure beneath the western Bohemian Massif obtained from teleseismic P and S receiver functions / Geoforschungszentrum Potsdam in der Helmholtz-Gemeinschaft. Barbara Heuer." Potsdam : Geoforschungszentrum, 2006. http://d-nb.info/98226769X/34.
Full text
23
Bojja, Venkatakrishnan Satheesh. "Simultaneous Transmit/Receive Multi-Functional Ultra-Wideband Transceiver with Reduced Hardware." The Ohio State University, 2017. http://rave.ohiolink.edu/etdc/view?acc_num=osu1499802814937457.
Full text
24
Lehto, Heather L. "Investigation of Stress Changes at Mount St. Helens, Washington, and Receiver Functions at the Katmai Volcanic Group, Alaska, with an Additional Section on the Assessment of Spreadsheet-based Modules." Scholar Commons, 2012. http://scholarcommons.usf.edu/etd/4124.
Full textAbstract:
Forecasting eruptions using volcano seismology is a subject that affects the lives and property of millions of people around the world. However, there is still much to learn about the inner workings of volcanoes and how this relates to the chance of eruption. This dissertation attempts to increase the breadth of knowledge aimed at helping to understand when a volcano is likely to erupt and how large that eruption might be. Chapters 2 and 3 focus on a technique that uses changes in the local stress field beneath a volcano to determine the source of these changes and help forecast eruptions, while Chapter 4 focuses on a technique that shows great potential to be used to image magma chambers beneath volcanoes by using receiver functions.
In Chapters 2 and 3 the source mechanisms of shallow volcano-tectonic earthquakes recorded at Mount St. Helens are investigated by calculating hypocenter locations and fault plane solutions (FPS) for shallow earthquakes recorded during two eruptive periods (1981-1986 and 2004-2008) and two non-eruptive periods (1987-2004 and 2008-2011). FPS show a mixture of normal, reverse, and strike-slip faulting during all periods, with a sharp increase in strike-slip faulting observed in 1987-1997 and an increase in normal faulting between 1998 and 2004 and again on September 25-29, 2004. FPS P-axis orientations (a proxy for ó1) show a ~90° rotation with respect to regional ó1 (N23°E) during 1981-1986 and 2004-2008, bimodal orientations (~N-S and ~E-W) during 1987-2004, and bimodal orientations at ~N-E and ~S-W from 2008-2011. These orientations are believed to be due to pressurization accompanying the shallow intrusion and subsequent eruption of magma as domes during 1981-1986 and 2004-2008, and the buildup of pore pressure beneath a shallow seismogenic volume during 1987-2004 and 2008-2011.
Chapter 4 presents a study using receiver functions, which show the relative response of the Earth beneath a seismometer. Receiver functions are produced by deconvolving the vertical component of a seismogram from the horizontal components. The structure of the ground beneath the seismometer can then be inferred from the arrivals of P-to-S converted phases. Receiver functions were computed for the Katmai Volcanic Group, Alaska, at two seismic stations (KABU and KAKN) between January 2005 and July 2011. Receiver functions from station KABU clearly showed the arrival of the direct P-wave and the arrival from the Moho; however, receiver functions from station KAKN did not show the arrival from the Moho. In addition, changes in the amplitude and polarity of arrivals on receiver functions suggested that the structure beneath both KABU and KAKN was complex. Station KABU is likely underlain by dipping layers and/or anisotropy, while station KAKN may lie over a basin structure, an attenuating body, or some other highly complex structure. However, it is impossible to say for certain what the structure is under either station as the azimuthal coverage is poor and thus the structure is unable to be modeled.
This dissertation also includes a section (Chapter 6) on the assessment of spreadsheet-based modules used in two Introductory Physical Geology courses at the University of South Florida (USF). When faculty at USF began using spreadsheet-based modules to help teach students math and geology concepts the students complained that they spent more time learning how to use Excel than they did learning the concepts presented in the modules. To determine whether the sharp learning curve for Excel was hindering learning we divided the students in two Introductory Physical Geology courses into two groups: one group was given a set of modules which instructed them to use Excel for all calculations; the other group was simply told to complete the calculations but was not instructed what method to use. The results of the study show that whether or not the students used Excel had very little to do with the level of learning they achieved. Despite complaints that Excel was hindering their learning, students in the study attained high gains for both the math and geology concepts presented in the modules whether they used Excel or not.
25
Dreiling, Jennifer [Verfasser]. "Crustal structures in southern Madagascar and Sri Lanka in the context of Gondwana’s assembly and break-up : A study based on surface wave dispersion and receiver functions / Jennifer Dreiling." Berlin : Freie Universität Berlin, 2020. http://d-nb.info/121203175X/34.
Full text
26
Pesce, Kathryn A. "Comparison of receiver function deconvolution techniques." Thesis, Massachusetts Institute of Technology, 2010. http://hdl.handle.net/1721.1/62748.
Full textAbstract:
Thesis (S.B.)--Massachusetts Institute of Technology, Dept. of Mechanical Engineering, September 2010."September 2010." Cataloged from PDF version of thesis.
Includes bibliographical references (p. 33-34).
Receiver function (RF) techniques are commonly used by geophysicists to image discontinuities and estimate layer thicknesses within the crust and upper mantle. A receiver function is a time-series record of the P-to-S (Ps) teleseismic wave conversions within the earth and can be viewed as the Earth's impulse response. An RF is extracted from seismic data by deconvolving the observed trace from an estimate of the source wavelet. Due to the presence of noise in the data, the deconvolution is unstable and must be regularized. Six deconvolution techniques are evaluated and compared based on their performance with synthetic data sets. These methods approach the deconvolution problem from either the frequency or time domain; some approaches are based on iterative least-squares inversions, while others perform a direct inverse of the problem. The methods also vary in their underlying assumptions concerning the noise distribution of the data set, level of automation, and the degree of objectivity used in deriving or choosing the regularization parameter. The results from this study provide insight into the situations for which each deconvolution method is most reliable and appropriate.
by Kathryn A. Pesce.
S.B.
27
Budweg, Martin. "Der obere Mantel in der Eifel-Region untersucht mit der Receiver-Function-Methode." Phd thesis, [S.l.] : [s.n.], 2002. http://pub.ub.uni-potsdam.de/2003/0011/budweg.pdf.
Full text
28
Edme, Pascal. "Can we apply the receiver function method to OBC data?" Paris, Institut de physique du globe, 2007. http://www.theses.fr/2007GLOB0018.
Full textAbstract:
In this thesis, we review the Receiver Function (RF) method, conceived many years ago in earthquake seismology, to see whether it can also be used in reflection seismology, and more specifically to see whether it can be applied to ocean-bottom-cable (OBC) data. The conventional RF method is used to determine the local PS wave response of a target zone below a multi-component 3C receiver and has been originally designed to process individual earthquake data of constant ray parameter p, acquired at the free surface. The target is illuminated from below. The converted PS wavefield generated at the receiver side is isolated from the global earth response by deconvolving the horizontal Ux component with the vertical Uz component, where Uz is assumed to contain only the impinging P waves (i. E. The unpredictable effective source function). Simultaneously to the source signature removal, the effect of the deconvolution can be subdivided into two steps: (1) P-PS wave separation and (2) multiples removal. The keyword is combination between components (by adaptive subtraction) or equivalently ratio between components. Our motivation is to reproduce these two steps with OBC data, in order to determine the (separated) primary PP and PS responses generated in the sub-seafloor area. However, there are several issues that require special attention when we implement the RF technique to OBC acquisition geometry. Firstly, the target (i. E. The sub-seafloor) is illuminated from above. Therefore there exist three types of incident waves at the receiver level: the upgoing P and PS wavefields (Pup and Sup as for land data) but also the additional downgoing P wavefield (Pdown). Secondly these wavefields are mixed between the components with time varying ray parameters, which precludes the possibility of applying the RF approach in the conventional time-offset domain. These problems can be addressed by taking into account the additional measurement of the pressure wavefield by the hydrophone Uh and by transforming the data in the ¿ -p domain (requiring fine receiver spacing usually afforded by OBCs). This transformation reorders the data by incidence angle at the receiver level, such that the pure upgoing PP and PS wavefields can be separated, based on polarization angle discrimination. This first step partially addresses the problem of multiples in the data by removing the downgoing (receiver side) water multiples, but it requires the knowledge of the seafloor properties as inputs. The other advantage of the ¿ ¡ p domain is that the water multiple reverberation becomes periodic. Remaining pure upgoing (source-side) water multiples are fully predictable (in contrast to overlapping source-side and receiver-side multiples) and can therefore be removed using predictive deconvolution (this is the required second step). Our adapted version of the RF technique uses the various ratios between components to estimate the elastic properties at the seafloor, as well as calibration operators, required for the decomposition. Our data-driven method can be automatically applied with a minimum of user-defined inputs, by taking advantages of the coherency between adjacent p traces and the redundancy of informations within the multiples. The strategy has been successfully applied to field data. Our results suggest several avenues for further processing
29
Nishimura, Koji. "Functional extension of atmospheric radar with digital receiver array." 京都大学 (Kyoto University), 2006. http://hdl.handle.net/2433/135947.
Full text
30
Cox, Hugh Franklin 1974. "Seismic discontinuities and order estimation using wavelets : a receiver function approach." Thesis, Massachusetts Institute of Technology, 2002. http://hdl.handle.net/1721.1/53181.
Full textAbstract:
Thesis (S.M.)--Massachusetts Institute of Technology, Dept. of Earth, Atmospheric, and Planetary Sciences, 2002.Includes bibliographical references (leaves 111-113).
In this thesis, I explore the use of non-linear wavelet techniques to estimate the order and scale of velocity discontinuties in the mantle transition zone through waveform analysis of Pds converted waves. The converted phases are isolated through a single station/multiple event receiver function technique which uses a wavelet deconvolution and denoising known as WaRD. It is an edge-preserving damped least squares solution with a small water level and subsequent wavelet thresholding. The deconvolved data is then imaged through an imaging technique which maps the conversions to the depth domain. The Pds phases are then isolated through a windowing and weighting, and then matched to a fractional order spline using a greedy matching pursuit algorithm. The data for this study consists of 2 Australian stations, CAN (Geoscope) and WRAB (IRIS), and 5 Japanese stations (JIZ, SGN, TKA, TMR, and TYM) from the F-Net array (formerly Freesia). CAN and WRAB are located in a relatively quiet continental tectonic setting, while the Japanese stations are in a more complex subduction zone environment. TKA (southern Japan) and TMR (northern Japan) are each thought to be underlain by a single subducting slab. JIZ, SGN, and TYM are located in central Japan where the Pacific and Philippine plates meet, and the subduction zone is thought to be very complex, with 2 slabs intersecting directly below these stations. Order and scale estimates for both Pds phases were obtained for CAN, WRAB, and SGN, and only P410s and P660 estimates were obtained for JIZ and TYM, respectively. Signal complexity in the image stacks prevented the determination of order estimates in either Pds phase for TKA and TMR. Order and scale estimates for the 410km discontinuity range between 0.325-0.450, and 18-35, respectively. Estimates for the order and scale of the 660km discontinuity range between 0.225-0.325 and 23-31, respectively. The order estimates for the P410s at CAN and WRAB were lower (0.325) than the estimates at JIZ and SGN (0.400-0.450), while the order estimates for the P660s at CAN and WRAB were higher (0.325-0.350) than the estimates for SGN and TYM (0.225-0.275). The results are consistent with a mixture type model in which the shape of the velocity discontinuity is a cusp-like feature and is caused by a critical density of one mineral phase with another. The ability to determine the order and scale and possible lateral variations could have major implications for the current views of discontinuities in the mantle transition zone.
by Hugh Franklin Cox.
S.M.
31
Li, Jian-Cheng. "Generation of simulated ultrasound images using a Gaussian smoothing function." Ohio : Ohio University, 1995. http://www.ohiolink.edu/etd/view.cgi?ohiou1179261418.
Full text
32
Stankiewicz, Jacek Maciej. "Receiver function analysis of crustal and upper mantle structure beneath Southern Africa." Master's thesis, University of Cape Town, 2001. http://hdl.handle.net/11427/4226.
Full text
33
Fagoonee, Lina. "A multi-functional turbo receiver based on partial unit memory codes." Thesis, Lancaster University, 2003. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.418684.
Full text
34
Zhang, Xiaofan. "Function of CikA in the cyanobacterial circadian system: the pseudo-receiver domain of CikA regulates the circadian input pathway." Texas A&M University, 2006. http://hdl.handle.net/1969.1/4261.
Full textAbstract:
The circadian input kinase gene (cikA) was first identified from a Tn5 mutant
of Synechococcus elongatus PCC 7942. A cikA null strain shows a striking
phenotype related to circadian gene regulation: all sampled loci show a
shortened circadian period and reduced amplitude of oscillation and a failure to
exhibit a wild-type resetting of the phase of the rhythm after an environmental
signal. This global defect in response to the environment suggests a key role for
CikA in the circadian input pathways. Bioinformatics results classify CikA as a
divergent member of the bacteriophytochrome family, suggesting a role in light
signal transduction. In vitro analysis previously showed that CikA is a bona fide
histidine protein kinase (HPK), and its kinase activity is regulated by the
presence of other domains. Its own pseudo-receiver (PsR) domain is not the
cognate receiver domain of its kinase HPK domain, and its GAF domain does
not likely bind a bilin chromophore as do photoreceptive phytochromes. Recent
results suggested that CikA may function as a redox-sensor. In this study, we examined the function of each domain of CikA using
different mutant cikA alleles, and determined their phenotypes with respect to
complementation of a null mutant and overexpression in both wild type and cikA
null strains. All domains except the featureless N-terminus were required for
CikA function. Overexpression of all mutant alleles that encoded the PsR
domain, whether or not the HPK was functional, caused a dominant arrhythmia
phenotype. In the absence of PsR, overexpressed variants did not cause
arrhythmia, but affected the amplitude and period of oscillation. The results
suggest a model in which the PsR domain regulates kinase activity and
mediates interaction with other input pathway components to allow CikA to reach
the correct cellular position to fulfill its function. Cellular localization assays
showed CikA can interact with a complex and showed a polar localization
pattern, whereas its variant without PsR showed uniform distribution in the cell.
In summary, CikA is an autoregulated kinase in which the PsR domain
regulates activity of the HPK domain and also serves as an interaction module to
lead the CikA to a specific cellular position.
35
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.
Full textAbstract:
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.
36
Davis, M. W. "A receiver function study of the crust and mantle beneath the British Isles." Thesis, University of Cambridge, 2010. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.598396.
Full textAbstract:
A seismic experiment across the British Isles was undertaken to probe the structure of both the crust and mantle in order to constrain the causes of Cenozoic uplift. Seismic data were processed using an iterative deconvolution method to produce receiver functions showing P-to-S conversions from velocity contrasts beneath each seismometer. Data processed for the crust show arrivals of direct conversions and multiples that are consistent with a Moho at around 31 km depth and an average VP/VS ratio of 1.71. The Moho shallows to the northwest of Scotland and southwest of England by ~5 km and deepens to the east of Scotland and beneath Wales by ~4 km. The Moho depths were combined with previous reflection and refraction results to produce a detailed Moho depth map of the entire region. The residual topography increases to the northwest and is attributed to dynamic support from the Icelandic Plume. Migrated receiver functions show considerable similarities of both Moho structure and intra-crustal layering to modelled results of existing controlled-source wide-angle surveys. The crustal dataset allowed both inverse and forward modelling of the receiver functions to resolve crustal velocity structure beneath each seismometer. The velocity models show deep crustal layering beneath areas associated with Early Cenozoic magmatism. The layers correlate with Cenozoic denudation patterns and may be interpreted as magmatic underplating, which caused permanent uplift and resulting denudation.
37
Tomlinson, James Peter. "A teleseismic receiver function study of the crustal structure of the British Isles." Thesis, University of Leicester, 2003. http://hdl.handle.net/2381/30454.
Full textAbstract:
The onshore crustal and upper mantle velocity structure of the British Isles has been investigated by teleseismic receiver function analysis. The results of the study augment the dense offshore and sparse onshore models of the structure beneath the area. In total almost 1500 receiver functions have been analysed, which have been calculated using teleseismic data from 34 broadband and short-period, three-component seismic recording instruments. The crustal structure has primarily been investigated using 1D grid search and forward modelling techniques, returning crustal thicknesses, bulk crystal Vp/Vs ratio and velocity-depth models. Upper mantle structures have been investigated by applying Ps moveout corrections and migration techniques to the observed broadband receiver functions. H-k stacking reveals crustal thicknesses between 25-36 km and Vp /Vs ratios between 1.6-1.9. The crustal thicknesses correlate with the results of previous seismic reflection and refraction profile to within +/- 2km. The exceptions are the stations close to the lapetus suture where the receiver function crustal thicknesses are up to 5 km less than the seismic refraction Moho. This mismatch has been attributed to the presence of underplated magmatic material at the base of the crust. 1D forward modelling has revealed sub-crustal structures. In northern Scotland these correspond with the Flannan and W-reflectors. The isolated sub-crustal structure at station GIM on the Isle if Man may be related to the closure of the lapetus ocean. Ps conversion from the 410 km and 660 km discontinuities have been identified in the Ps moveout corrected receiver functions. The differential delay time between the phases is close to the global average of 24s, indicating that there is no significant thermal anomaly in the mantle transition zone beneath the British Isles. A discontinuity at ~220 km has been identified as the Lehmann discontinuity. A 30 km step in the Lehmann discontinuity close to the lapetus suture may be interpreted as juxtaposition of Laurentian and Avalonian mantle.
38
George, Kiranraj. "Design and Performance Evaluation of 1 Giga Hertz Wideband Digital Receiver." Wright State University / OhioLINK, 2007. http://rave.ohiolink.edu/etdc/view?acc_num=wright1183662240.
Full text
39
Cassidy, John Francis. "Teleseismic receiver function analysis of the crust and upper mantle of southwestern British Columbia." Thesis, University of British Columbia, 1991. http://hdl.handle.net/2429/30966.
Full textAbstract:
The northern Cascadia subduction zone has been the site of numerous geophysical studies during the past two decades. However, little is known of the deep structure (> 40 km) or S-velocities throughout this region. In this study, locally generated P-to-S conversions (Ps) contained in ~100 teleseismic P-wave coda have been analysed to determine the S-velocity structure to upper mantle depths.
Prior to the analysis, the applications and limitations of this technique as applied to a dipping layer environment have been examined. It is concluded that strict stacking bounds (≤ 10° in ∆ and BAZ) should be applied. It is demonstrated that dipping boundaries which could not be detected using this technique (e.g. ∆Vs = 0.08 km/s), may significantly alter the amplitude and arrival time of reverberations from deeper interfaces. Therefore, such phases should not be quantitatively modelled. As reverberations are an important constituent of receiver functions, formal inversion of these waveforms is not justified in this environment. Only arrivals which exhibit the amplitude and arrival time characteristics of primary P-to-S conversions are considered in this study. Finally, most studies have normalised receiver functions to unit amplitude prior to modelling. However, synthetic data demonstrate that undetected dipping boundaries may alter Ps/P ratios and lead to inaccurate earth models. A recent modification to this technique (Ammon, 1991) which provides 'absolute' amplitudes is examined. In addition to providing information on the near-surface velocity structure and on dipping layers, this modification provides for a more accurate image of the earth structure.
Three 3-component broadband event triggered seismic stations were deployed in a 90 km long linear array oriented perpendicular to the continental margin of southwestern British
Columbia. Between December 1987 and October 1989 approximately 100 teleseisms covering
a wide azimuthal and distance range were recorded and analysed.
The two largest phases observed in data from the westernmost station ALB-B reveal a prominent low-velocity zone extending from 37-41 km depth beneath central Vancouver Island. This feature correlates well with the reflective 'E' zone, a region which also exhibits high electrical conductivity. Combining the S-velocity estimates with refraction P-velocities yields a high Poisson's ratio for this layer. The low P- and S-velocities and high Poisson's ratio and electrical conductivity are supportive of the recent interpretation of this feature as a fluid-saturated shear zone above the subducting Juan de Fuca (JdF) plate. Analysis of data at the mid-array and easternmost sites, LAS and EGM respectively, permits this zone to be mapped northeastward to a depth of 54 km beneath the British Columbia mainland, approximately 250 km from the locus of subduction.
The subducting oceanic crust is imaged at 47-53 km depth dipping 15°±5° in the direction N30°E±20° beneath central Vancouver Island. The dip angle increases to 22° ±5° at a depth of 60-65 km beneath the Strait of Georgia. The results of this analysis provide the first definitive evidence for the location of the subducting plate in this region and indicates that the seismicity at depth occurs within the oceanic crust. Further, the dip direction of N30°E supports the theory (Rogers, 1983) that the JdF plate is arched upwards as it subducts in this region.
Finally, the continental Moho is imaged at 36 km depth beneath LAS, and there is evidence
at both this site and EGM for a low-velocity zone in the lower crust. A similar feature is imaged beneath Vancouver Island and coincides with the reflective ‘C’ zone. The depth estimated to the top of this layer denotes the lower limit of shallow seismicity suggesting a significant structural or compositional change at a depth of 20-26 km.Science, Faculty of
Earth, Ocean and Atmospheric Sciences, Department of
Graduate
40
Ueno, Tomotake. "Subsurface discontinuities derived from receiver function analysis in southwest Japan : relation to seismic activity." 京都大学 (Kyoto University), 2007. http://hdl.handle.net/2433/136772.
Full text
41
Mohsen, Ayman. "A receiver function study of the crust and upper mantle across the dead sea transform." [S.l. : s.n.], 2004. http://www.diss.fu-berlin.de/2004/53/index.html.
Full text
42
O'Cull, Douglas C. "A COMPACT, LIGHTWEIGHT, LOW POWER, MULTI-FUNCTION TELEMETRY RECEIVER/COMBINER SYSTEM PROVIDES "HANDS OFF" AUTOMATION FOR SYSTEMS COST REDUCTION." International Foundation for Telemetering, 1994. http://hdl.handle.net/10150/608841.
Full textAbstract:
International Telemetering Conference Proceedings / October 17-20, 1994 / Town & Country Hotel and Conference Center, San Diego, CaliforniaWith the increased concerns for reducing cost and improving reliability in today's telemetry systems, many users are employing simulation and automation to guarantee reliable telemetry systems operation. This places an increased demand on the remote capabilities of the equipment used in the telemetry system. Furthermore, emphasis has been placed on the ability to decrease the space and power consumption of the telemetry system to facilitate transportability of the a single telemetry system to multiple sites. Finally, today's telemetry systems demand that all equipment provide multiple functions to provide the maximum performance for the lowest system cost.
43
Dzierma, Yvonne [Verfasser]. "A receiver function study of Southern Costa Rica : indications of steep Cocos Ridge subduction / Yvonne Dzierma." Kiel : Universitätsbibliothek Kiel, 2009. http://d-nb.info/1019811420/34.
Full text
44
Rytsälä, Heikki. "Functional and work disability and treatment received by patients with major depressive disorder." Helsinki : University of Helsinki, 2006. http://ethesis.helsinki.fi/julkaisut/laa/kliin/vk/rytsala/.
Full text
45
Olsson, Sverker. "Analyses of Seismic Wave Conversion in the Crust and Upper Mantle beneath the Baltic Shield." Doctoral thesis, Uppsala University, Department of Earth Sciences, 2007. http://urn.kb.se/resolve?urn=urn:nbn:se:uu:diva-7930.
Full textAbstract:
Teleseismic data recorded by broad-band seismic stations in the Swedish National Seismic Network (SNSN) have been used in a suite of studies of seismic wave conversion in order to assess the structure of the crust and upper mantle beneath the Baltic Shield. Signals of seismic waves converted between P and S at seismic discontinuities within the Earth carry information on the velocity contrast at the converting interface, on the depth of conversion and on P and S velocities above this depth.
The conversion from P to S at the crust-mantle boundary (the Moho) provides a robust tool to constrain crustal thicknesses. Results of such analysis for the Baltic Shield show considerable variation of Moho depths and significantly improve the Moho depth map. Analysis of waves converted from S to P in the upper mantle reveals a layered lithosphere with alternating high and low velocity bodies. It also detects clear signals of a sharp velocity contrast at the lithosphere-asthenosphere boundary at depths around 200 km.
Delay times of P410s, the conversion from P to S at the upper mantle discontinuity at 410 km depth, were used in a tomographic inversion to simultaneously determine P and S velocities in the upper mantle. The polarisation of P410s was also used to study anisotropy of the upper mantle. Results of these analyses are found to be in close agreement with independently derived results from arrival time tomography and shear-wave splitting analysis of SKS.
The results presented in this thesis demonstrate the ability of converted wave analysis as a tool to detect and image geological boundaries that involve sharp contrasts in seismic properties. The results also show that this analysis can provide means of studying aspects of Earth’s structure that are conventionally studied using other types of seismic data.
46
Sarathy, Vivek. "High Spurious-Free Dynamic Range Digital Wideband Receiver for Multiple Signal Detection and Tracking." Wright State University / OhioLINK, 2007. http://rave.ohiolink.edu/etdc/view?acc_num=wright1197910677.
Full text
47
Moore, Natalie. "The Effect of Receiver Nonlinearity and Nonlinearity Induced Interference on the Performance of Amplitude Modulated Signals." Thesis, Virginia Tech, 2018. http://hdl.handle.net/10919/84899.
Full textAbstract:
All wireless receivers have some degree of nonlinearity that can negatively impact performance. Two major effects from this nonlinearity are power compression, which leads to amplitude and phase distortions in the received signal, and desensitization caused by a high powered interfering signal at an adjacent channel. As the RF spectrum becomes more crowded, the interference caused by these adjacent signals will become a more significant problem for receiver design. Therefore, having bit and symbol error rate expressions that take the receiver nonlinearity into account will allow for determining the linearity requirements of a receiver. This thesis examines the modeling of the probability density functions of M-PAM and M-QAM signals through an AWGN channel taking into account the impact of receiver nonlinearity. A change of variables technique is used to provide a relationship between the pdf of these signals with a linear receiver and the pdf with a nonlinear receiver. Additionally, theoretical bit and symbol error rates are derived from the pdf expressions. Finally, this approach is extended by deriving pdf and error rate expressions for these signals when nearby blocking signals cause desensitization of the signal of interest. Matlab simulation shows that the derived expressions for a nonlinear receiver have the same accuracy as the accepted expressions for linear receivers.Master of Science
48
Alinaghi, Alireza. "Receiver function analysis of the crust and upper mantle from the north german basin to the archean baltic shield." [S.l. : s.n.], 2003. http://www.diss.fu-berlin.de/2003/159/index.html.
Full text
49
Budweg, Martin [Verfasser]. "Der obere Mantel in der Eifel-Region untersucht mit der Receiver-function-Methode / Geoforschungszentrum Potsdam. Vorgelegt von Martin Budweg." Potsdam : Geoforschungszentrum, 2002. http://d-nb.info/967756448/34.
Full text
50
Liu, Hua. "ASYMPTOTIC PROPERTIES OF PARTIAL AREAS UNDER THE RECEIVER OPERATING CHARACTERISTIC CURVE WITH APPLICATIONS IN MICROARRAY EXPERIMENTS." UKnowledge, 2006. http://uknowledge.uky.edu/gradschool_diss/463.
Full textAbstract:
Receiver operating characteristic (ROC) curves are widely used in medical decision making. It was recognized in the last decade that only a specific region of the ROC curve is of clinical interest, which can be summarized by the partial area under the ROC curve (partial AUC). Early statistical methods for evaluating partial AUC assume that the data are from a specified underlying distribution. Nonparametric estimators of the partial AUC emerged recently, but there are theoretical issues to be addressed. In this dissertation, we propose two new nonparametric statistics, partially integrated ROC and partially integrated weighted ROC, for estimating partial AUC. We show that our partially integrated ROC statistic is a consistent estimator of the partial AUC, and derive its asymptotic distribution which is distribution free under the null hypothesis. In the partially integrated ROC statistic, when the ROC curve crosses the Uniform distribution function (CDF) and if the partial area evaluated contains the crossing point, or when there are multiple crossing, the partially integrated ROC statistic might not perform well. To address this issue, we propose the partially integrated weighted ROC statistic. This statistic evaluates the partially weighted AUC, where larger weight is given when the ROC curve is above the Uniform CDF and smaller weight is given when the ROC curve is below the Uniform CDF. We show that our partially integrated weighted ROC statistic is a consistent estimator of the partially weighted AUC. We derive its asymptotic distribution which is distribution free under the null hypothesis. We propose to apply our two nonparametric statistics to functional category analysis in microarray experiments. We define the functional category analysis to be the statistical identification of over-represented functional gene categories in a microarray experiment based on differential gene expression. We compare our statistics with existing methods for the functional category analysis both via simulation study and application to a real microarray data, and demonstrate that our two statistics are effective for identifying over-represented functional gene categories. We also emphasize the essential role of the empirical distribution function plots and the ROC curves in the functional category analysis.