Dissertations / Theses on the topic 'Focal Depths'
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Huang, Paul Yi-Fa. "Focal depths and mechanisms of mid-ocean ridge earthquakes from body waveform inversion." Thesis, Massachusetts Institute of Technology, 1985. http://hdl.handle.net/1721.1/54310.
Microfiche copy available in Archives and Science
Bibliography: leaves 230-249.
by Paul Yi-Fa Huang.
Ph.D.
Dahal, Nawa. "Improving the determination of moment tensors, moment magnitudes and focal depths of earthquakes below Mw 4.0 using regional broadband seismic data:." Thesis, Boston College, 2019. http://hdl.handle.net/2345/bc-ir:108624.
Thesis advisor: John E. Ebel
Determining accurate source parameters of small magnitude earthquakes is important to understand the source physics and tectonic processes that activate a seismic source as well as to make more accurate estimates of the probabilities of the recurrences of large earthquakes based on the statistics of smaller earthquakes. The accurate determination of the focal depths and focal mechanisms of small earthquakes is required to constrain the potential seismic source zones of future large earthquakes, whereas the accurate determination of seismic moment is required to calculate the sizes (best represented by moment magnitudes) of earthquakes. The precise determination of focal depths, moment magnitudes and focal mechanisms of small earthquakes can help greatly advance our knowledge of the potentially active faults in an area and thus help to produce accurate seismic hazard and risk maps for that area. Focal depths, moment magnitudes and focal mechanisms of earthquakes with magnitudes Mw 4.0 and less recorded by a sparse seismic network are usually poorly constrained due to the lack of an appropriate method applicable to find these parameters with a sparse set of observations. This dissertation presents a new method that can accurately determine focal depths, moment magnitudes and focal mechanisms of earthquakes with magnitudes between Mw 4.0 and Mw 2.5 using the broadband seismic waveforms recorded by the local and regional seismic stations. For the determination of the focal depths and the moment magnitudes, the observed seismograms as well as synthetic seismograms are filtered through a bandpass filter of 1-3 Hz, whereas for the determination of the focal mechanisms, they are filtered through a bandpass filter of 1.5-2.5 Hz. Both of these frequency passbands have a good signal-to-noise ratio (SNR) for the small earthquakes of the magnitudes that are analyzed in this dissertation. The waveforms are processed to their envelopes in order to make the waveforms relatively simple for the modeling. A grid search is performed over all possible dip, rake and strike angles and as well as over possible depths and scalar moments to find the optimal value of the focal depth and the optimal value of the scalar moment. To find the optimal focal mechanism, a non-linear moment-tensor inversion is performed in addition to the coarse grid search over the possible dip, rake and strike angles at a fixed value of focal depth and a fixed value of scalar moment. The method of this dissertation is tested on 18 aftershocks of Mw between 3.70 and 2.60 of the 2011 Mineral, Virginia Mw 5.7 earthquake. The method is also tested on 5 aftershocks of Mw between 3.62 and 2.63 of the 2013 Ladysmith, Quebec Mw 4.5 earthquake. Reliable focal depths and moment magnitudes are obtained for all of these events using waveforms from as few as 1 seismic station within the epicentral distance of 68-424 km with SNR greater or equal to 5. Similarly, reliable focal mechanisms are obtained for all of the events with Mw 3.70-3.04 using waveforms from at least 3 seismic stations within the epicentral distance of 60-350 km each with SNR greater or equal to 10. Tests show that the moment magnitudes and focal depths are not very sensitive to the crustal model used, although systematic variations in the focal depths are observed with the total crustal thickness. Tests also show that the focal mechanisms obtained with the different crustal structures vary with the Kagan angle of 30o on average for the events and the crustal structures tested. This means that the event moment magnitudes and event focal mechanism determinations are only somewhat sensitive to the uncertainties in the crustal models tested. The method is applied to some aftershocks of the Mw 7.8, 2015 Gorkha, Nepal earthquake which shows that the method developed in this dissertation, by analyzing data from eastern North America, appears to give good results when applied in a very different tectonic environment in a different part of the world. This study confirms that the method of modeling envelopes of seismic waveforms developed in this dissertation can be used to extract accurate focal depths and moment magnitudes of earthquakes with Mw 3.70-2.60 using broadband seismic data recorded by local and regional seismic stations at epicentral distances of 68-424 km and accurate focal mechanisms of earthquakes with Mw 3.70-3.04 using broadband seismic data recorded by local and regional seismic stations at epicentral distances of 60-350 km
Thesis (PhD) — Boston College, 2019
Submitted to: Boston College. Graduate School of Arts and Sciences
Discipline: Physics
Laporte, Marine. "Contribution à l'amélioration de l’estimation de la profondeur hypocentrale à partir de réseaux régionaux ou globaux." Electronic Thesis or Diss., Université Paris sciences et lettres, 2022. http://www.theses.fr/2022UPSLE055.
This thesis focuses on the different methods of estimating hypocentral depth and on the identification of localization uncertainties that may be associated with them. At a regional distance, we use these methods to map small hypocentral depth variations related to the activity of the Great Himalayan Thrust in Nepal or to analyze opportunistic seismic crisis. The effects of different sources of uncertainty on the hypocentral depths are quantified through a global Sobol-Monte Carlo sensitivity analysis. To improve the estimation of the hypocentral depth at teleseismic distance, we develop a new method of depth identification from the pP/sP arrivals in the energetic envelopes of the teleseismic signals. An adaptation of this teleseismic envelopes method allows us to highlight relative lateral depth variations along subduction interfaces in Chile and Ecuador. The different scales of observations and the different depth estimation techniques are compared on intermediate magnitude events (M>5) in order to characterize the depth uncertainty at teleseismic distance, to highlight or quantify specific sources of bias or to reinforce some regional seismotectonic interpretations
Hu, Xinda. "Development Of The Depth-Fused Multi-Focal-Plane Display Technology." Diss., The University of Arizona, 2014. http://hdl.handle.net/10150/338957.
Massey, Kristen L. "Procedural Calibration of Haploscope Wings to Establish Accurate Focal Vergence Depth." Thesis, Mississippi State University, 2019. http://pqdtopen.proquest.com/#viewpdf?dispub=10980275.
This thesis project was undertaken with the intent to discover the source of a known but hitherto unexplained error in the calibration of the wings for a haploscope used in depth perception studies.
The angles of the haploscope wings are used to control the vergence angle of the virtual images projected into each eye. This accounts for a strong depth cue used in AR and depth perception studies. Two experiments were devised to both display and attempt to characterize the error between the theoretical wing angles needed to cause a user’s vision to verge at some focal depth and the actual wing angles that caused vergence. The investigation revealed a near-constant offset between the theoretical and actual angles needed. This suggests that the error may not stem from the haploscope alignment itself, but from how the center of the user’s eye is currently modeled.
Gupta, Divya. "An Empirical Study of the Effects of Context-Switch, Object Distance, and Focus Depth on Human Performance in Augmented Reality." Thesis, Virginia Tech, 2004. http://hdl.handle.net/10919/33507.
Secondly, focus depth, which is an important parameter and a depth cue, may affect the userâ s view of the augmented world. If focus depth is not adjusted properly, it may result in vision-based difficulties and reduce speed, accuracy, and comfort while using an augmented reality display. Thus, the second goal of this thesis was to study the effect of focus depth on task performance in augmented reality systems.
In augmented reality environments, real-world and virtual information are found at different distances from the user. To focus at different depths, the userâ s eye needs to accommodate and converge, which may strain the eye and degrade performance on tasks. However, no research in augmented reality has explored this issue. Hence, the third goal of this thesis was to determine if distance of virtual information from the user impacts task performance.
To accomplish these goals, a 3x3x3 within subjects design was used. The experimental task for the study required the user to repeatedly switch eye focus between the virtual text and real-world text. A monocular see-through head- mounted display was used for this research.
Results of this study revealed that switching between real-world and virtual information in augmented reality is extremely difficult when information is displayed at optical infinity. Virtual information displayed at optical infinity may be unsuitable for tasks of the nature used in this research. There was no impact of focus depth on user task performance and hence it is preliminarily recommended that manufacturers of head-mounted displays may only need to make fixed focus depth displays; this clearly merits additional intensive research. Further, user task performance was better when focus depth, virtual information, and real-world information were all at the same distance from the user as compared to conditions when they were mismatched. Based on this result we recommend presenting virtual information at the same distance as real-world information of interest.
Master of Science
Paerhati, Paruku. "Real-time monocular depth mapping system using variance of focal plane and pixel focus measure." Thesis, Massachusetts Institute of Technology, 2017. http://hdl.handle.net/1721.1/113117.
This electronic version was submitted by the student author. The certified thesis is available in the Institute Archives and Special Collections.
Cataloged from student-submitted PDF version of thesis.
Includes bibliographical references (page 48).
Vision is one of the most powerful senses available to creatures. Undoubtedly, many of the fundamental operations of humans, such as the ability to plan paths, avoid obstacles, and recognize objects, depend heavily on their visual perception of the world around them. Although humans have naturally evolved to efficiently use their stereo optical prowess to develop an understanding of their environment, artificial machines and systems in comparison have just begun to utilize computer vision to create awareness of local physical entities. One of the most important sensory skills creatures have is depth perception, which allows them to estimate the relative distance of objects in their vision from many visual cues. Many systems have been developed to aid machines in perceiving the depth map of their environment, and each system has its drawbacks and benefits. In this paper, we introduce the design and implementation of a new system which provides a depth map from the use of a single optical camera with focal plane variation in the images taken. The paper focuses on the methods used to scale the depth from focus algorithm to perform in real-time. The results also showcase a real-time depth mapping system capable of providing rich depth maps of scenes at a high framerate and with advanced noise filtration techniques.
by Paruku Paerhati.
M. Eng.
Rodriguez, Joaquin. "Calibration and 3D vision with a color-polarimetric camera." Electronic Thesis or Diss., Bourgogne Franche-Comté, 2023. http://www.theses.fr/2023UBFCK062.
Among the different sensing modalities, vision sensors are the ones thatprovide the most abundant environmental information. Additionally, the usage ofa short focal length lens allows to easily increase the observed area. The releaseof color and polarimetric imagers makes it possible to extend even more thepolarimetric application related to depth estimation. Indeed, the polarizationparameters of the reflected light are related to the nature and to the geometryof the objects, which can be used advantageously. In this thesis, our mainobjective is to study the usage of polarization data to enhance theperception capabilities applied to robotics tasks, particularly in the task ofscene depth reconstruction. Furthermore, we aim to push the knowledge in thefield of polarization imaging by providing other researchers with a set of toolsthat will allow them to quickly access the polarization modality. After doing acomplete introduction to the polarization theory and modeling, we describe howto calibrate a DoFP sensor. This sensing device allows to capture twomodalities (color and polarization) with a single snapshot. The new calibrationtechnique that we propose enables this device to provide more accuratemeasurements by fitting a mathematical model to each individual pixel. Themethod we present here aims to reduce the amount of equipment and, thus theexperimental time required to obtain calibrated measurements. We make a detailedexplanation of the physics underlying the Shape-from-Polarization technique, which enablesthe normal field estimation of an object by using polarization cues. All therequired equations as well as their inverted versions for deriving the vectorparameters from the polarization state are detailed while taking intoconsideration the type of reflection and material. We also put in evidence theeffects of our calibration algorithm over the estimation of the normal vectorfield by using polarization. The estimation of depth information usingartificial intelligence has seen significant growth in recent years. In thiscontext, we also propose a deep-learning network to estimate depth based on amiddle-fusion architecture, and a polarimetric loss function. The objective ofthis development is to show how to effectively integrate the polarization theoryconstraints into a data-driven algorithm. A qualitative and quantitativeevaluation of the results shows the interest of using an RGB-polarimetric imagerthanks to the contribution of the polarization information. During this researchwork, a complete software toolbox was also developed, providing the scientificcommunity with simplified access to polarimetric imaging
Kosmata, Marcel. "Elastische Rückstoßatomspektrometrie leichter Elemente mit Subnanometer-Tiefenauflösung." Doctoral thesis, Saechsische Landesbibliothek- Staats- und Universitaetsbibliothek Dresden, 2012. http://nbn-resolving.de/urn:nbn:de:bsz:14-qucosa-84041.
In this thesis the QQDS magnetic spectrometer that is used for high resolution ion beam analysis (IBA) of light elements at the Helmholtz-Zentrum Dresden-Rossendorf is presented for the first time. In addition all parameters are investigated that influence the analysis. Methods and models are presented with which the effects can be minimised or calculated. There are five focal points of this thesis. The first point is the construction and commissioning of the QQDS magnetic spectrometer, the corresponding scattering chamber with all the peripherals and the detector, which is specially developed for high resolution elastic recoil detection. Both the reconstructed spectrometer and the detector were adapted to the specific experimental conditions needed for high-resolution Ion beam analysis of light elements and tested for routine practice. The detector consists of two compo-nents. At the back end of the detector a Bragg ionization chamber is mounted, which is used for the particle identification. At the front end, directly behind the entrance window a proportional counter is mounted. This proportional counter includes a high-resistance anode. Thus, the position of the particles is determined in the detector. The following two points concern fundamental studies of ion-solid interaction. By using a magnetic spectrometer the charge state distribution of the particles scattered from the sample after a binary collision is both possible and necessary for the analysis. For this reason the charge states are measured and compared with existing models. In addition, a model is developed that takes into account the charge state dependent energy loss. It is shown that without the application of this model the depth profiles do not correspond with the quantitative measurements by conventional IBA methods and with the thickness obtained by transmission electron microscopy. The second fundamental ion-solid interaction is the damage and the modification of the sample that occurs during heavy ion irradiation. It is shown that the used energies occur both electronic sputtering and electronically induced interface mixing. Electronic sputtering is minimised by using optimised beam parameters. For most samples the effect is below the detection limit for a fluence sufficient for the analysis. However, the influence of interface mixing is so strong that it has to be included in the analysis of the layers of the depth profiles. It is concluded from these studies that at the Rossendorf 5 MV tandem accelerator chlorine ions with an energy of 20 MeV deliver the best results. In some cases, such as the analysis of boron, the energy must be reduced to 6.5 MeV in order to retain the electronic sputtering below the detection limit. The fourth focus is the study of the influence of specific sample properties, such as surface roughness, on the shape of a measured energy spectra and respectively on the analysed depth profile. It is shown that knowledge of the roughness of a sample at the surface and at the interfaces for the analysis is needed. In addition, the contribution parameters limiting the depth resolution are calculated and compared with the conventional ion beam analysis. Finally, a comparison is made between the high-resolution ion beam analysis and complementary methods published by other research groups. The fifth and last focus is the analysis of light elements in ultra thin layers. All models presented in this thesis to reduce the influence of beam damage are taken into account. The dynamic non-equilibrium charge state is also included for the quantification of elements. Depth profiling of multilayer systems is demonstrated for systems consisting of SiO2-Si3N4Ox-SiO2 on silicon, boron implantation profiles for ultra shallow junctions and ultra thin oxide layers, such as used as high-k materials
Jing, Ruei-Ci Jhang, and 張簡瑞祈. "Bionic Compound Eye Microlens Array With Multifocus and Long Focal Depth." Thesis, 2016. http://ndltd.ncl.edu.tw/handle/82428857462599080295.
國立中興大學
精密工程學系所
104
This study aims to develop a bionic compound eye microlens array with multifocus and high depth of field to improve a selected vision quality. There are seven layers of microlens array designed in the bionic compound eye. These microlens array will focus on the same point composed a visual system. There are two parts in this study. The first part is the calculation of each layer''s microlens array focus on the same surfaces, Then the light path can be simulate using fabricated by the optic simulation software, ZEMAX. The second part is the bionic microlens array compound eye fabrication. The photoresist column array fabricated by lithography and followed by the thermal reflow can form the microlens array. A plastic replicate by elastic PDMS was used after sputtering. Then 3D printer was used to print the PDMS model which was hemisphere with some openings on the top, attached the replicated microlens array on the openings. The microlens array can from the curvature compound eye microlens array because of the negative pressure resulted in the hemisphere. A curvature with microlens array for the bionic compound eye, can be fabricated. The ZEMAX software can be used to simulate .
Sheng-HanLin and 林聖翰. "Relationship Between Aftershock Productivities and Earthquake Magnitude, Focal Depth and Heat Flow in Taiwan." Thesis, 2011. http://ndltd.ncl.edu.tw/handle/37249302652499645442.
Wang, Chih-Huang, and 王志煌. "Novel Reflective Type of Barcode Reader with Single LED Source, Microstructure and Long Focal Depth." Thesis, 2003. http://ndltd.ncl.edu.tw/handle/12253199368931142439.
國立臺灣科技大學
電子工程系
91
This paper presents a novel reflective type of barcode reader with single LED source, microstructure and long focal depth. We have designed the feasibility and it can achieve more high performance than conventional CCD bar code reader having scanning width and depth of field relating the spot size. And in this final result of simulation, the scanning length can achieve 114mm and the depth of focus is about 30mm. In design process, for the structure, we inject a new idea with reflection and microstructure into the bar code reader system. In addition to spot size, it is also emphasized and obtained that the ratio between the peaks in both sides of imaging plane and the valley at the middle of imaging plane is 2:1. Note the ratio is influenced by the LED luminance and the resolution of CCDs. And it can obtain the request with intensity ratio that only uses the different type of random gradual change type of microstructure device.
Lin, Hui-Hsiung, and 林暉雄. "Research on the Application for Long Focal Depth and Dual Wavelength Diffractive Optical Elements on Optical Pickup Heads." Thesis, 2000. http://ndltd.ncl.edu.tw/handle/64503340463532049827.
國立交通大學
光電工程所
88
In recent years, as the semiconductor technologies progress continuously, the high-tech industries have achieved considerable technical and commercial success. Furthermore, the consuming electronic products are also developed along the trends of lightweight, miniaturization, and multi-function. Some of the conventional optical elements have been replaced by diffractive optical elements (DOEs), which make the design of the optical pickup head system toward miniaturizing and modularizing. The application of diffractive optical elements with long focal depth and dual wavelength on optical pickup head is studied in the thesis. The merits and drawbacks of various structures of pickup head are evaluated firstly, then some novel ideas and design concepts are proposed and established by theoretical deduction and algorithm, computer simulation analysis, practical fabrication, and measurement verification. The design of DVD (digital versatile disks) optical pickup head with dual wavelength diffractive focal lens and the pseudo-nondiffracting beam (PNDB) characteristic is carried out by using a conjugate-gradient method. Because the focal length of optical pickup head is very short (within 1.8-2.4 mm), it is extremely smaller than the near field diffractive region. Consequently, the integral function of the Bessel term, belonging to the linear transfer equation of Fresnel diffraction integral function within the paraxial approximation, could not be neglected in the free space. But it resulted in high complexity, lower convergence and heavy computing load during the simulating procedure. The axial intensity distribution can be presented by selecting a trapezoid profile. The performances of designed DOEs are evaluated by using an error function with 2-D weighting factor and radiant flux factor. The analysis results show the whole convergence has increased 8-9 orders and the non-uniformity of axial intensity has decreased 2 orders. A simple structure with multi-function is successfully designed and fabricated in the study. The objective lens and collimator lens have been integrated as the diffractive optical elements. This implies that the problems of assemble and optical alignment of many elements will be solved completely. Moreover, the increased lateral resolution and expand longitudinal axial distribution in this novel diffractive optical elements have been demonstrated by theoretical analysis and experimental results.
Hutchinson, Jesse. "Delineation of the Nootka fault zone and structure of the shallow subducted southern Explorer plate as revealed by the Seafloor Earthquake Array Japan Canada Cascadia Experiment (SeaJade)." Thesis, 2020. http://hdl.handle.net/1828/11768.
Graduate
Kosmata, Marcel. "Elastische Rückstoßatomspektrometrie leichter Elemente mit Subnanometer-Tiefenauflösung." Doctoral thesis, 2011. https://tud.qucosa.de/id/qucosa%3A25920.
In this thesis the QQDS magnetic spectrometer that is used for high resolution ion beam analysis (IBA) of light elements at the Helmholtz-Zentrum Dresden-Rossendorf is presented for the first time. In addition all parameters are investigated that influence the analysis. Methods and models are presented with which the effects can be minimised or calculated. There are five focal points of this thesis. The first point is the construction and commissioning of the QQDS magnetic spectrometer, the corresponding scattering chamber with all the peripherals and the detector, which is specially developed for high resolution elastic recoil detection. Both the reconstructed spectrometer and the detector were adapted to the specific experimental conditions needed for high-resolution Ion beam analysis of light elements and tested for routine practice. The detector consists of two compo-nents. At the back end of the detector a Bragg ionization chamber is mounted, which is used for the particle identification. At the front end, directly behind the entrance window a proportional counter is mounted. This proportional counter includes a high-resistance anode. Thus, the position of the particles is determined in the detector. The following two points concern fundamental studies of ion-solid interaction. By using a magnetic spectrometer the charge state distribution of the particles scattered from the sample after a binary collision is both possible and necessary for the analysis. For this reason the charge states are measured and compared with existing models. In addition, a model is developed that takes into account the charge state dependent energy loss. It is shown that without the application of this model the depth profiles do not correspond with the quantitative measurements by conventional IBA methods and with the thickness obtained by transmission electron microscopy. The second fundamental ion-solid interaction is the damage and the modification of the sample that occurs during heavy ion irradiation. It is shown that the used energies occur both electronic sputtering and electronically induced interface mixing. Electronic sputtering is minimised by using optimised beam parameters. For most samples the effect is below the detection limit for a fluence sufficient for the analysis. However, the influence of interface mixing is so strong that it has to be included in the analysis of the layers of the depth profiles. It is concluded from these studies that at the Rossendorf 5 MV tandem accelerator chlorine ions with an energy of 20 MeV deliver the best results. In some cases, such as the analysis of boron, the energy must be reduced to 6.5 MeV in order to retain the electronic sputtering below the detection limit. The fourth focus is the study of the influence of specific sample properties, such as surface roughness, on the shape of a measured energy spectra and respectively on the analysed depth profile. It is shown that knowledge of the roughness of a sample at the surface and at the interfaces for the analysis is needed. In addition, the contribution parameters limiting the depth resolution are calculated and compared with the conventional ion beam analysis. Finally, a comparison is made between the high-resolution ion beam analysis and complementary methods published by other research groups. The fifth and last focus is the analysis of light elements in ultra thin layers. All models presented in this thesis to reduce the influence of beam damage are taken into account. The dynamic non-equilibrium charge state is also included for the quantification of elements. Depth profiling of multilayer systems is demonstrated for systems consisting of SiO2-Si3N4Ox-SiO2 on silicon, boron implantation profiles for ultra shallow junctions and ultra thin oxide layers, such as used as high-k materials.