Marine electromagnetic (EM) geophysics is an up-and-coming branch of the geosciences that is allowing for the advancement in our understanding of key properties of the oceanic lithosphere and subduction dynamics, particularly in how deformation manifests geophysically and how it evolves through time and under various conditions. This dissertation focuses on two unique marine EM data sets collected at the Hikurangi subduction zone, New Zealand, and on 33 Ma Pacific lithosphere. Analysis of the former, which constitutes the bulk of this dissertation, offers the first kilometer-scale characterization of offshore, margin-wide electrical resistivity variations at a subduction zone and provides an electrical framework for discussing the potential causes of along-strike differences in megathrust slip at the Hikurangi Margin. The latter data set is used to constrain electrical anisotropy of the shallow lithosphere, which enables an interpretation of the deformation history of normal oceanic lithosphere. Chapter 2 of this dissertation gives a brief overview of the physical underpinnings of EM methods with attention given to the marine magnetotelluric (MT) and controlled-source electromagnetic (CSEM) methods. Maxwell's equations are reviewed and the relevant derivations leading to the temporal and spatial behavior of EM waves for the frequencies used in this dissertation (~0.001--0.1 Hz) are presented. Chapter 3 focuses on the tectonic background of the Hikurangi Margin and on processing of the MT and CSEM data. Interest in the Hikurangi Margin has arisen both because of its proximity to the inhabitants of New Zealand and due to the recognition of several properties that vary along the strike of the margin. The most intriguing of those variations, and most concerning from a natural hazard perspective, are the along-strike change in interseismic coupling and slow slip event (SSE) occurrence, with stronger coupling and deeper, infrequent SSEs realized in the southern Hikurangi Margin and weaker coupling and shallower, more frequent SSEs in the north. Several proposed causes of these variations are cited, including differences in sediment thickness and roughness of the incoming plate, changes in the plate interface geometry, and the effect of geological terranes in the forearc on pore pressure. But the degree to which any or all of these factors affect interseismic coupling remains an open question. The remainder of Chapter 3 is devoted to detailing the steps involved in processing the marine MT and CSEM data. A workflow for optimizing MT response function estimation is presented and improvements to the marine CSEM processing scheme are described. In Chapter 4 of this dissertation, inversions of the data collected at the southern Hikurangi Margin are presented, and these resistivity models are compared with co-located seismic data. Individual inversions of the CSEM and MT data along with joint inversion of the two data sets highlights the distinct sensitivities and resolving capabilities of each data type. A thick (4--6 km) sediment package covers the Hikurangi Plateau of the incoming plate. The plateau itself is evident as a dipping resistor (>10 Ω-m) that approximately corresponds with the seismically interpreted depth of the Hikurangi Plateau. Resistors in the shallow forearc are interpreted as free gas or gas hydrate, which is prevalent at the Hikurangi Margin. A resistive anomaly beneath one of two main ridges appears to comprise the footwall of a thrust fault, which potentially implies a high permeability system that allows for preferential dewatering of the footwall. Using available P-wave velocity data for this region, equations relating resistivity to velocity are derived. The resistivity presented in Chapter 4 and Archie's law are used to derive porosity models of the southern Hikurangi profile in Chapter 5. Vertical compaction is shown to dominate trends in porosity. A reference compaction porosity model is approximated and removed from the resistivity-derived porosity model in order to identify porosity trends distinct from compaction. A deepening in the negative porosity anomaly of the shallow incoming plate sediments as they approach the trench suggests these sediments experience compression several kilometers seaward of the main frontal thrust. This could represent the early stages of protothrust zone development. An increasingly positive porosity anomaly observed in the sedimentary unit just above the Hikurangi Plateau as it nears the trench may indicate heightened fluid overpressures in an incipient décollement. In Chapter 6 of this dissertation, inversions of the central Hikurangi Margin are shown and discussed. Compared to resistivity in the southern Hikurangi Margin, the forearc and incoming plate of the central Hikurangi Margin are more complex in their resistivity structure, possibly due to the impact of rougher seafloor. Extensive evidence for free gas or gas hydrates is found as shallow resistive anomalies in these models. Other anomalous resistors may correspond to exhumed terranes in the forearc. Anomalous forearc conductors could indicate sediment underplating or damage zones associated with subducting topography. Chapter 7 shows the resistivity and porosity of the northern Hikurangi Margin and offers the first detailed electrical image of a seamount prior to and during subduction. The seamount on the incoming plate is shown to have a thin, resistive cap that traps a conductive matrix of porous volcaniclastics and altered material over a resistive core. Again applying Archie's law to estimate porosity from resistivity reveals that the seamount will allow ~3.2--4.7x more water than normal, unfaulted oceanic lithosphere to subduct with the seamount. In the forearc, a sharp, resistive peak on the slab is interpreted as the core of a subducting seamount. This cone of high resistivity lies directly beneath a prominent conductive anomaly in the upper plate. Burst-type repeating earthquakes and other seismicity from a recent SSE cluster in and around this conductive anomaly, which seems to implicate the subducting seamount in the generation of fluid-rich damage zones in the forearc. The interaction of the subducting topography with the upper plate will thus alter the effective normal stress at the plate interface by modulating fluid overpressure. The results in this chapter show that subducting topography can transport large volumes of water to the forearc and that such topography is able to severely modify the structure and physical conditions of the upper plate, which may influence the location and timing of SSEs. Finally, Chapter 8 provides a robust constraint on the electrical azimuthal anisotropy of oceanic lithosphere. The data for this chapter were collected in a region of oceanic lithosphere removed from the influence of plate boundaries and intraplate volcanism. The survey design was chosen to maximize azimuthal coverage so as to constrain the directional dependence of resistivity. Inversions of the data resulted in an anisotropic resistivity model wherein the crust is ~18-36x more conductive in the paleo mid-ocean ridge direction than the perpendicular paleo-spreading direction. In the uppermost mantle conductivity is ~29x higher in the paleo-spreading direction. The crustal anisotropy is interpreted to result from sub-vertical porosity created by ridge parallel normal faulting during extension of the young crust and thermal stress-driven cracking from cooling of mature crust. Anisotropy in the uppermost mantle implies that shearing of mantle olivine during plate formation generates a strong electrical signal that is preserved as the plate ages. Reanalysis of EM data collected offshore Nicaragua suggests that the Pacific Plate electrical anisotropy is not a local anomaly but rather may be prevalent throughout oceanic lithosphere.

京都大学 / 新制・課程博士 / 博士(工学) / 甲第23478号 / 工博第4890号 / 新制||工||1764(附属図書館) / 京都大学大学院工学研究科社会基盤工学専攻 / (主査)教授 川池 健司, 教授 藤田 正治, 准教授 米山 望 / 学位規則第4条第1項該当 / Doctor of Philosophy (Engineering) / Kyoto University / DFAM

Les micro-résonateurs (MRs) sont devenus des éléments clés de la conception de capteurs optiques intégrés, car étant plus miniaturisés que l’existant, ils s’intègrent mieux dans des systèmes ''lab-on-chip'', ce qui permet aussi de réduire le volume des molécules à détecter. Les MRs sont de plus très sensibles à la variation d’indice effectif provoquée par la présence de molécules dans le milieu de détection. Dans cette thèse, nous avons utilisé deux types de matériaux différents: les polymères et le silicium poreux. Les polymères, facilement réalisables avec des méthodes de fabrication peu onéreuses, sont dans un premier temps utilisés pour valider les outils de simulation développés pour l’étude des caractéristiques des MRs pour l’application capteur basée sur la détection par évanescence. Le silicium poreux permet d'exploiter un autre mode de détection, la détection en volume. Les molécules présentes dans le milieu de détection s'infiltrent dans le matériau et réagissent de manière directe avec la lumière. En utilisant les outils de simulation développés et en adaptant le procédé de photolithographie classique utilisé pour la fabrication de MRs en polymères, des premiers MRs constitués de guides ridges à base de silicium poreux sont mis en œuvre et caractérisés. Ces travaux de thèse démontrent expérimentalement la possibilité de détecter des concentrations de glucose avec une meilleure sensibilité que l'état de l'art pouvant atteindre les 600 nm/RIU, pour les domaines utilisant la détection et l'analyse de molécules (santé-agro, défense-sécurité, environnement). / Micro-resonators have become key element for integrated optical sensor because they offer the advantage of significantly minimizing the device size, which allows an easily integration on lab-on-chip and greatly reduces the amount of molecules to be detected. Moreover, micro-resonators are extremely sensitive to the effective index variation induced by the presence of molecules in the detection medium. The thesis focuses on two different materials: polymers and porous silicon. Firstly, polymers, easily implementable with a low cost fabrication, are used to validate the simulation tools developed for the study of micro-resonators characteristics in order to perform sensing application based on the detection by evanescence. Then, porous silicon is investigated in order to operate another type of detection, the detection by volume. The molecules to be detected and present in the medium detection infiltrate into the material and interact directly with the light. Using simulation tools and by adapting the photolithographic process used for polymers micro-resonators fabrication, the first micro-resonators based on porous silicon ridge waveguides are obtained and characterized. The work contained in this thesis demonstrate experimentally the possibility of sensing concentrations of glucose with a sensitivity of 600 nm/RIU, using volume detection, which is higher than the state of the art, for domains using the sensing and analysis of molecules (health, food industries, security and environment).

The aim of this thesis is to comprehensively analyze and describe one of the oldest methods of individual identification of individuals, which originates in ancient civilizations and consists of identifying a person on the basis of unique drawings of his papillary terrain. The dactyloscopy will be viewed primarily from a criminalistic perspective, although the text also deals with its expansion and use in other areas of human life. This is also a current trend, whose tendencies can be expected in the future. The thesis is divided into three basic chapters - history, present, future, which will gradually summarize the whole issue of this established forensic science. The text is supplemented with pictures and photographs with regard to practical use of this method. The first part of the thesis deals with the history of dactyloscopy from the discovery of papillary lines by ancient cultures to the gradual introduction of scientific approach to this discipline, either from physiological point of view or later from the criminalistic point of view. The text focuses mainly on important personalities who have helped to develop dactyloscopy and put it into practice. At the end of this part, the historical background and the development of the doctrine of papillary lines in the Czech Republic are also...

Thesis (Ph. D.)--Joint Program in Oceanography (Massachusetts Institute of Technology, Dept. of Earth, Atmospheric, and Planetary Sciences; and the Woods Hole Oceanographic Institution), 2001. / "September 2001." Vita. Page 223 blank. / Includes bibliographical references. / This thesis studies interactions between mid-ocean ridges and mantle plumes using geophysics, geochemistry, and geodynamical modeling. Chapter 1 investigates the effects of the Marion and Bouvet hotspots on the ultra-slow spreading, highly-segmented Southwest Indian Ridge (SWIR). Gravity data indicate that both Marion and Bouvet impart high-amplitude mantle Bouguer anomaly lows to the ridge axis, and suggest that long-offset transforms may diminish along-axis plume flow. Building upon this observation, Chapter 2 presents a series of 3D numerical models designed to quantify the sensitivity of along-axis plume-driven mantle flow to transform offset length, spreading rate, and mantle viscosity structure. The calculations illustrate that long-offset transforms in ultra-slow spreading environments may significantly curtail plume dispersion. Chapter 3 investigates helium isotope systematics along the western SWIR as well as near a global array of hotspots. The first part of this study reports uniformly low 3He/4He ratios of 6.3-7.3 R/Ra along the SWIR from 9⁰-24⁰E, compared to values of 8 +/- 1 Ra for normal mid-ocean ridge basalt. The favored explanation for these low values is addition of (U+Th) into the mantle source by crustal and/or lithospheric recycling. Although high He/4He values have been observed along the SWIR near Bouvet Island to the west, there is no evidence for elevated 3He/4He ratios along this section of the SWIR. The second part of Chapter 3 investigates the relationship between 3He/4He ratios and geophysical indicators of plume robustness for nine hotspots. / (cont.) A close correlation between a plume's flux and maximum 3He/4He ratio suggests a link between plume upwelling strength and origination in the deep, relatively undegassed mantle. Chapter 4 studies 3D mantle flow and temperature patterns beneath oceanic ridge-ridge-ridge triple junctions (TJs). In non-hotspot-affected TJs with geometry similar to the Rodrigues TJ, temperature and upwelling velocity along the slowest-spreading of the three ridges are predicted to increase within a few hundred kilometers of the TJ, to approach those of the fastest-spreading ridge. Along the slowest-spreading branch in hotspot-affected TJs such as the Azores, a strong component of along-axis flow directed away from the TJ is predicted to advect a hotspot thermal anomaly away from its deep-seated source. / by Jennifer E. Georgen. / Ph.D.

Thesis (S.M.)--Joint Program in Oceanography/Applied Ocean Science and Engineering (Massachusetts Institute of Technology, Dept. of Earth, Atmospheric, and Planetary Sciences; and the Woods Hole Oceanographic Institution), 2004. / Includes bibliographical references (leaves 68-69). / Methods which measure seafloor resistivity are uniquely suited to studying hydrothermal circulation in the crust. The magnetometric resistivity (MMR) technique is a galvanic method which uses a bipole current source with a magnetometer receiver. The resistivity of the subsurface can be estimated from the magnetic field read in MMR. In order to analyze and invert MMR data taken near Mid Ocean Ridges, it is important to understand the effects of ridge topography on MMR models. To analyze these effects a 3D MMR forward modeling program MMR3Df̲wd is used to model Mid Ocean Ridges with varying slopes, resistivities, and source/receiver geometries. The modeled magnetic fields are compared with models with a flat seafloor to determine the impact of the ridge topography. Results show that for some of the ridges modeled, the effects of the topography were significant, suggesting that in some instances it is important to include ridge topography in forward models to obtain accurate results from data inversion. / by Lisa A. Lassner. / S.M.

In this study, friction spot welding was used to join DP980 steel sheet. Four different ultra-hard tool materials were used with the objective of determining which tool material produced the highest number of acceptable-strength welds. Three of the tools were composed of various mixtures of polycrystalline cubic Boron Nitride (PCBN), Tungsten, and Rhenium. These materials are referred to herein as Q60, Q70, and Q80, the "Qxx" designation denoting the percentage of the volume of the tool material composed of PCBN. The fourth tool tested was composed entirely of PCBN. The Q70 tool produced approximately 1100 welds of acceptable strength before average weld strength decreased below the acceptable value, and the Q60 tool produced approximately 600 welds of acceptable strength. The Q80 material did not produce any welds with strengths above the acceptable value. However, Q80 produced the greatest number of welds of consistent strength. The PCBN tool, being the hardest, also did not produce any welds of acceptable strength, and failed at 257 welds. This failure is presumed to be a result of a tool/parameter mismatch which caused excessive loads on the tool. This research revealed that the weld parameters and tool materials used in this study will not generally provide for feasibility of implementation in industry. Further advances in weld parameter selection, tool geometry, and tool materials will be necessary in order to make friction spot joining of high strength steels an economically viable option.

No description available.

Two threats to bats are especially pervasive in the central Appalachian Mountains of the eastern United States: a fungal disease called White-nose Syndrome (WNS) and wind energy development. White-nose Syndrome has caused the death of millions of bats in North America, and multiple hibernating bat species are affected in the central Appalachians. Wind energy is one of the most rapidly-growing energy sources in eastern United States, and bats are often killed when they fly near wind turbines. Fatality rates at wind turbines is highest in bat species that migrate instead of hibernate. There is limited data on bats during the autumn and spring seasons in the central Appalachian Mountains, and the impacts of WNS and wind energy development may be exacerbated during these seasons. Therefore, I sought to determine patterns and drivers of activity for hibernating bat species during autumn and spring around hibernacula. Similarly, I set out to determine patterns and drivers of activity for migratory bat species during autumn and spring along mountain ridgelines in the central Appalachians. Lastly, I searched for evidence of potential WNS-induced changes in the summer ecology of the once common northern long eared bat. This study can help elucidate patterns of bat activity during largely understudied seasons. Furthermore, it can provide useful information needed by land managers to implement actions that could help alleviate and/or avoid potential additive negative impacts on bat species with existing conservation concerns. / MS

Nos travaux de recherches présentés dans ce manuscrit ont pour objectif, l'optimisation des performances des algorithmes de suivi des formants. Pour ce faire, nous avons commencé par l'analyse des différentes techniques existantes utilisées dans le suivi automatique des formants. Cette analyse nous a permis de constater que l'estimation automatique des formants reste délicate malgré l'emploi de diverses techniques complexes. Vue la non disponibilité des bases de données de référence en langue arabe, nous avons élaboré un corpus phonétiquement équilibré en langue arabe tout en élaborant un étiquetage manuel phonétique et formantique. Ensuite, nous avons présenté nos deux nouvelles approches de suivi de formants dont la première est basée sur l'estimation des crêtes de Fourier (maxima de spectrogramme) ou des crêtes d'ondelettes (maxima de scalogramme) en utilisant comme contrainte de suivi le calcul de centre de gravité de la combinaison des fréquences candidates pour chaque formant, tandis que la deuxième approche de suivi est basée sur la programmation dynamique combinée avec le filtrage de Kalman. Finalement, nous avons fait une étude exploratrice en utilisant notre corpus étiqueté manuellement comme référence pour évaluer quantitativement nos deux nouvelles approches par rapport à d'autres méthodes automatiques de suivi de formants. Nous avons testé la première approche par détection des crêtes ondelette, utilisant le calcul de centre de gravité, sur des signaux synthétiques ensuite sur des signaux réels de notre corpus étiqueté en testant trois types d'ondelettes complexes (CMOR, SHAN et FBSP). Suite à ces différents tests, il apparaît que le suivi de formants et la résolution des scalogrammes donnés par les ondelettes CMOR et FBSP sont meilleurs qu'avec l'ondelette SHAN. Afin d'évaluer quantitativement nos deux approches, nous avons calculé la différence moyenne absolue et l'écart type normalisée. Nous avons fait plusieurs tests avec différents locuteurs (masculins et féminins) sur les différentes voyelles longues et courtes et la parole continue en prenant les signaux étiquetés issus de la base élaborée comme référence. Les résultats de suivi ont été ensuite comparés à ceux de la méthode par crêtes de Fourier en utilisant le calcul de centre de gravité, de l'analyse LPC combinée à des bancs de filtres de Mustafa Kamran et de l'analyse LPC dans le logiciel Praat. D'après les résultats obtenus sur les voyelles /a/ et /A/, nous avons constaté que le suivi fait par la méthode ondelette avec CMOR est globalement meilleur que celui des autres méthodes Praat et Fourier. Cette méthode donne donc un suivi de formants (F1, F2 et F3) pertinent et plus proche de suivi référence. Les résultats des méthodes Fourier et ondelette sont très proches dans certains cas puisque toutes les deux présentent moins d'erreurs que la méthode Praat pour les cinq locuteurs masculins ce qui n'est pas le cas pour les autres voyelles où il y a des erreurs qui se présentent parfois sur F2 et parfois sur F3. D'après les résultats obtenus sur la parole continue, nous avons constaté que dans le cas des locuteurs masculins, les résultats des deux nouvelles approches sont notamment meilleurs que ceux de la méthode LPC de Mustafa Kamran et ceux de Praat même si elles présentent souvent quelques erreurs sur F3. Elles sont aussi très proches de la méthode par détection de crêtes de Fourier utilisant le calcul de centre de gravité. Les résultats obtenus dans le cas des locutrices féminins confirment la tendance observée sur les locuteurs / Our research work presented in this thesis aims the optimization of the performance of formant tracking algorithms. We began by analyzing different existing techniques used in the automatic formant tracking. This analysis showed that the automatic formant estimation remains difficult despite the use of complex techniques. For the non-availability of database as reference in Arabic, we have developed a phonetically balanced corpus in Arabic while developing a manual phonetic and formant tracking labeling. Then we presented our two new automatic formant tracking approaches which are based on the estimation of Fourier ridges (local maxima of spectrogram) or wavelet ridges (local maxima of scalogram) using as a tracking constraint the calculation of center of gravity of a set of candidate frequencies for each formant, while the second tracking approach is based on dynamic programming combined with Kalman filtering. Finally, we made an exploratory study using manually labeled corpus as a reference to quantify our two new approaches compared to other automatic formant tracking methods. We tested the first approach based on wavelet ridges detection, using the calculation of the center of gravity on synthetic signals and then on real signals issued from our database by testing three types of complex wavelets (CMOR, SHAN and FBSP). Following these tests, it appears that formant tracking and scalogram resolution given by CMOR and FBSP wavelets are better than the SHAN wavelet. To quantitatively evaluate our two approaches, we calculated the absolute difference average and standard deviation. We made several tests with different speakers (male and female) on various long and short vowels and continuous speech signals issued from our database using it as a reference. The formant tracking results are compared to those of Fourier ridges method calculating the center of gravity, LPC analysis combined with filter banks method of Kamran.M and LPC analysis integrated in Praat software. According to the results of the vowels / a / and / A /, we found that formant tracking by the method with wavelet CMOR is generally better than other methods. Therefore, this method provides a correct formant tracking (F1, F2 and F3) and closer to the reference. The results of Fourier and wavelet methods are very similar in some cases since both have fewer errors than the method Praat. These results are proven for the five male speakers which is not the case for the other vowels where there are some errors which are present sometimes in F2 and sometimes in F3. According to the results obtained on continuous speech, we found that in the case of male speakers, the result of both approaches are particularly better than those of Kamran.M method and those of Praat even if they are often few errors in F3. They are also very close to the Fourier ridges method using the calculation of center of gravity. The results obtained in the case of female speakers confirm the trend observed over the male speakers