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  • About
  • The Global ETD Search service is a free service for researchers to find electronic theses and dissertations. This service is provided by the Networked Digital Library of Theses and Dissertations.
    Our metadata is collected from universities around the world. If you manage a university/consortium/country archive and want to be added, details can be found on the NDLTD website.
61

Inversion of Hankel and Toeplitz matrices

Cho, Choong Yun, January 1970 (has links)
Thesis (Ph. D.)--University of Wisconsin--Madison, 1970. / Typescript. Vita. eContent provider-neutral record in process. Description based on print version record. Includes bibliography.
62

Reconstruction of stellar surface features via matrix lightcurve inversion /

Harmon, Robert Olin January 1999 (has links)
Thesis (Ph. D.)--University of Chicago, Dept. of Physics, August 1999. / Includes bibliographical references. Also available on the Internet.
63

Synthetic Aperture Radar Interferometry for Natural Disaster and Reservoir Monitoring / 干渉SAR解析を用いた自然災害と貯留層のモニタリングに関する研究

Mokhamad Yusup Nur Khakim 26 March 2012 (has links)
Kyoto University (京都大学) / 0048 / 新制・課程博士 / 博士(工学) / 甲第16815号 / 工博第3536号 / 新制||工||1535(附属図書館) / 29490 / 京都大学大学院工学研究科社会基盤工学専攻 / (主査)教授 松岡 俊文, 教授 小池 克明, 教授 田村 正行 / 学位規則第4条第1項該当
64

Processing and analysis of seismic reflection and transient electromagnetic data for kimberlite exploration in the Mackenzie Valley, NT

Moore, David Anton 05 1900 (has links)
The Lena West property near Lac des Bois, NT, held by Diamondex Resources Ltd., is an area of interest for exploration for kimberlitic features. In 2005, Frontier Geosciences Inc. was contracted to carry out seismic reflection and time-domain transient electromagnetic (TEM) surveys to investigate the possibility of kimberlite pipes being the cause of total magnetic intensity (TMI) anomalies previously identified on the property. One small part of the property, Area 1915, was surveyed with two perpendicular seismic reflection lines 1550 m and 1790 m long and three TEM lines consisting of six or seven individual soundings each with a 200 m transmitter loop. The results generated by Frontier Geosciences did not indicate any obvious vertical features that correlated with the TMI anomaly. The purpose of this study is to reprocess the seismic reflection data using different approaches than those of Frontier Geosciences and to invert the TEM data using a 1-D inversion code, EM1DTM recently developed by the UBC Geophysical Inversion Facility, to improve upon previous results and enhance the interpretation. A secondary objective is to test the robustness of EM1DTM when applied to observed TEM data, since prior to this study it had only been applied to synthetic data. Selective bandpass filtering, refraction and residual statics and f-x deconvolution procedures contributed to improved seismic images to the recorded two-way traveltime of 511.5 ms (approximately 1100 m depth). The TEM data were successfully inverted and converted to pseudo 2-D recovered resistivity sections that showed similar results to those from Frontier Geosciences. On the final seismic reflection sections, several strong reflectors are identified and the base of the overlying sedimentary layers is interpreted at a depth of ~600 m. The TEM results show consistent vertical structure with minimum horizontal variation across all lines to a valid depth of ~150 m. However, neither TEM nor seismic reflection results provide any information that correlates well with the observed TMI anomaly. / Science, Faculty of / Earth, Ocean and Atmospheric Sciences, Department of / Graduate
65

A study of stone fragmentation in shock wave lithotripsy by customizing the acoustic field and waveform shape

Chitnis, Parag Vijay January 2007 (has links)
Shock wave lithotripsy is the preferred treatment modality for kidney stones in the United States. Despite clinical use for over twenty-five years, the mechanisms of stone fragmentation are still under debate. A piezoelectric array was employed to examine the effect of waveform shape and pressure distribution on stone fragmentation in lithotripsy. The array consisted of 170 elements placed on the inner surface of a 15 cm-radius spherical cap. Each element was driven independently using a 170 individual pulsers, each capable of generating 1.2 kV. The acoustic field was characterized using a fiber optic probe hydrophone with a bandwidth of 30 MHz and a spatial resolution of 100 μm. When all elements were driven simultaneously, the focal waveform was a shock wave with peak pressures p+ =65±3MPa and p−=−16±2MPa and the −6 dB focal region was 13 mm long and 2 mm wide. The delay for each element was the only control parameter for customizing the acoustic field and waveform shape, which was done with the aim of investigating the hypothesized mechanisms of stone fragmentation such as spallation, shear, squeezing, and cavitation. The acoustic field customization was achieved by employing the angular spectrum approach for modeling the forward wave propagation and regression of least square errors to determine the optimal set of delays. Results from the acoustic field customization routine and its implications on stone fragmentation will be discussed. / National Institutes of Health DK043881
66

Accidental Inversion During 3d Rotation With 2-dof Input Devices

Diaz, Derek Daniel 01 January 2007 (has links)
This dissertation focuses on a human operator's ability to perform rotational control of a three-dimensional object using two-degrees of freedom (DOF) interface devices. Although input devices designed specifically for 3D interaction exist, devices traditionally used for two-dimensional user interaction, such as a mouse or joystick, have become ubiquitous to computer tasks. This research examines a particular human-computer interaction issue that arises from stimulus-response compatibility between three-dimensional stimuli spaces and 2-DOF response sets. The focal point of this research is a phenomenon referred to here as accidental inversion. Accidental inversions occur when an operator erroneously moves a three-dimensional object in a direction opposite than was intended. Thus, the effect of accidental inversion results from a mismatch between the operator's intended and actual input. A key assumption in diagnosing the causal factors involved in the accidental inversion effect is contribution from both internal (i.e., having to do with the individual) and external (i.e., having to do with the environment) influences. Three experiments were conducted to study accidental inversion. The first examined population stereotype, a measure of a target population's natural response tendencies to particular stimuli for a particular task. Results indicated a strong population stereotype for horizontal rotations (i.e., yaw) and weak stereotype for vertical rotations (i.e., pitch). This effect was mediated by whether the task was in the context of flight or ground-based movement. The second experiment analyzed the subjective preference for two opposite input-response (I-R) mappings (i.e., how the system responds to different input into the controlling device) for a task requiring control over vertical rotation. Results indicated that subjective preferences for I-R mappings were not heavily polarized. The third experiment also focused on vertical rotational control and examined how subjective preference for a particular I-R mapping affected performance. Furthermore, this experiment also examined performance when interference was introduced in the form of a temporary interruption where the participant had to conduct the task using an opposite I-R mapping. Results indicated that, upon being interrupted with the opposite I-R mapping, the group who used the mapping they subjectively preferred did worse than the group who used the mapping they did not prefer. This research has implications for the design of human-machine systems requiring human-in-the-loop three-dimensional rotational control. Some human-machine systems can have significant consequences from even a single mistake caused by a human-operator accidentally providing the wrong input. Findings from this research lead to two primary recommendations to the design of human-machine systems: a) an easily accessible and clearly indicated method to select input-response mapping which is provided before beginning the actual task, b) be informed of the current input-response mapping in use.
67

Display to Camera Calibration Techniques

Gatt, Philip 01 January 1984 (has links) (PDF)
In today's technology, with digitally controlled optic sensing devices, there exists a need for a fast and accurate calibration procedure. Typical display devices and optic fiber bundles are plagued with inaccuracies. There are many sources of error such as delay, time constants, pixel distortion, pixel bleeding, and noise. The calibration procedure must measure these inaccuracies, and compute a set of correction factors. These correction factors are then used in real time to alter the command data, such that the intended pixels are correctly commanded. This paper discusses a calibration procedure, which employs a special matrix inverse algorithm. This algorithm, which is only applicable to sparse symmetric band diagonal matrices, successfully inverts a 10,000 by 10,000 matrix in less than four seconds on a VAX-11/780. It is estimated that, when using conventional Gauss-Jordan matrix inverse techniques, 4800 hours are required to compute the same matrix inverse. This paper also documents the BlendI routines, which will be used as a calibration procedure for BlendI System.
68

STRUCTURAL FACTORIZATION OF SQUARES IN STRINGS

Bai, Haoyue 05 1900 (has links)
A balanced double square in a string x consists of two squares starting in the same position and of comparable lengths. We present a unique fac- torization of the longer square into primitive components refereed to as the canonical factorization and analyze its properties. In particular, we examine the inversion factors and the right and left inversion subfactors. All three substrings are collectively referred to as rare factors as they occur only twice in a signi cant portion of the larger square. The inversion factors were es- sential for determining the classi cation of mutual con gurations of double squares and thus providing the best-to-date upper bound of 11n=6 for the number of distinct squares in a string of length n by Deza, Franek, and Thierry. The right and left inversion subfactors have the advantage of being half the length of the inversion factors, thus providing a stronger dis- crimination property for a possible third square. This part of the thesis was published by Bai, Franek, and Smyth. The canonical factorization and the right and left inversion subfactors are used to formulate and prove a signi cantly stronger version of the New Periodicity Lemma by Fan, Puglisi, Smyth, and Turpin, 2006, that basically restricts what kind of a third square can exists in a balanced double square. This part of the thesis was published by Bai, Franek, and Smyth. The canonical factorization and the inversion factors are applied to for- mulate and prove a stronger version of the Three Squares Lemma by Crochemore and Rytter. This part of the thesis was published by Bai, Deza, and Franek. / Thesis / Doctor of Philosophy (PhD)
69

Topics in Copular Clauses

Bartošová, Jitka 11 1900 (has links)
This dissertation investigates syntax and semantics of copular clauses containing two NPs. Since Higgins (1973) four semantically distinct types of copular clauses have been recognized in the literature, i.e. predicational, equative, specificational, and identificational clauses. There are many proposals aiming to reduce the number of copular clause types via collapsing certain types into others. This dissertation contributes to the debate by providing novel evidence from Czech that identificational clauses are predicational and specificational clauses are inverted predicational or equative clauses. Czech provides an excellent tool to investigate copular clauses for three reasons: (i) rich phi-feature agreement, (ii) case alternation, (iii) analytical verbal morphology. Using the three properties Czech offers, I argue that specificational clauses are derived via scrambling of a structurally lower NP over a structurally higher NP. Consequently, I support the inversion analysis of specificational clauses (Moro, 1997; Den Dikken, 2006; Mikkelsen, 2006; Heycock, 2012, a.o.). I also argue that specificational clauses may be derived from both, predicational and equative clauses. In contrast, identificational clauses, despite their initial resemblance to specificational clauses, are argued not to involve inversion, therefore providing empirical support for Heller and Wolter (2008). I also present novel empirical data from Czech that show that the interpretation of the pronoun in identificational clauses is restricted by the copular agreement. In order to account for the restriction, I argue that both NPs in identificational clauses Agree with the copula via a Multiple-Agree chain (see Hiraiwa (2005)). / Thesis / Doctor of Philosophy (PhD)
70

Multiscale Seismic Inversion in the Data and Image Domains

Zhang, Sanzong 12 1900 (has links)
I present a general methodology for inverting seismic data in either the data or image domains. It partially overcomes one of the most serious problems with current waveform inversion methods, which is the tendency to converge to models far from the actual one. The key idea is to develop a multiscale misfit function that is composed of both a simplified version of the data and one associated with the complex part of the data. Misfit functions based on simple data are characterized by many fewer local minima so that a gradient optimization method can make quick progress in getting to the general vicinity of the actual model. Once we are near the actual model, we then use the gradient based on the more complex data. Below, we describe two implementations of this multiscale strategy: wave equation traveltime inversion in the data domain and generalized differential semblance optimization in the image domain. • Wave Equation Traveltime Inversion in the Data Domain (WT): The main difficulty with iterative waveform inversion is that it tends to get stuck in local minima associated with the waveform misfit function. To mitigate this problem and avoid the need to fit amplitudes in the data, we present a waveequation method that inverts the traveltimes of reflection events, and so is less prone to the local minima problem. Instead of a waveform misfit function, the penalty function is a crosscorrelation of the downgoing direct wave and the upgoing reflection wave at the trial image point. The time lag which maximizes the crosscorrelation amplitude represents the reflection-traveltime residual that is back-projected along the reflection wavepath to update the velocity. Shot- and angle-domain crosscorrelation functions are introduced to estimate the reflection-traveltime residual by semblance analysis and scanning. In theory, only the traveltime information is inverted and there is no need to precisely fit the amplitudes or assume a high-frequency approximation. Results with both synthetic data and field records reveal both the benefits and limitations of WT. • Generalized Differental Semblance Optimization in the Image Domain (GDSO): We now extend the multiscale physics approach to differential semblance optimization (DSO) in the image domain. That is, we identify the space-lag offset H(x, z, h) in the subsurface-offset domain as an implicit function of velocity. It describes the smoothly varying moveout H(x, z, h) of the migration image m(x, z, h) in the subsurface-offset domain, which is analogous to the smoothly varying traveltime residual ∆τ(x) of a reflection event in a shot gather. The velocity model is found that minimizes the objective function ∑x,z,h H(x, z, h)2m(x, z, h)2, where coherent noise is eliminated everywhere except along the picked curve H(x, z, h). This method is denoted as generalized DSO (GDSO) and mitigates the coherent noise problem with DSO. Numerical examples are presented that empirically demonstrate its effectiveness in providing more accurate velocity models compared to conventional DSO.

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