For most electromagnetic (EM) geophysical systems, the contamination of primary fields on secondary fields ultimately limits the capability of the controlled-source EM methods. Null coupling techniques were proposed to solve this problem. However, the small orientation errors in the null coupling systems greatly restrict the applications of these systems. Another problem encountered by most EM systems is the surface interference and geologic noise, which sometimes make the geophysical survey impossible to carry out. In order to solve these problems, the alternating target antenna coupling (ATAC) method was introduced, which greatly removed the influence of the primary field and reduced the surface interference. But this system has limitations on the maximum transmitter moment that can be used. The differential target antenna coupling (DTAC) method was proposed to allow much larger transmitter moments and at the same time maintain the advantages of the ATAC method. In this dissertation, first, the theoretical DTAC calculations were derived mathematically using Born and Wolf's complex magnetic vector. 1D layered and 2D blocked earth models were used to demonstrate that the DTAC method has no responses for 1D and 2D structures. Analytical studies of the plate model influenced by conductive and resistive backgrounds were presented to explain the physical phenomenology behind the DTAC method, which is the magnetic fields of the subsurface targets are required to be frequency dependent. Then, the advantages of the DTAC method, e.g., high-resolution, reducing the geologic noise and insensitive to surface interference, were analyzed using surface and subsurface numerical examples in the EMGIMA software. Next, the theoretical advantages, such as high resolution and insensitive to surface interference, were verified by designing and developing a low-power (moment of 50 Am²) vertical-array DTAC system and testing it on controlled targets and scaled target coils. At last, a high-power (moment of about 6800 Am²) vertical-array DTAC system was designed, developed and tested on controlled buried targets and surface interference to illustrate that the DTAC system was insensitive to surface interference even with a high-power transmitter and having higher resolution by using the large-moment transmitter. From the theoretical and practical analysis and tests, several characteristics of the DTAC method were found: (1) The DTAC method can null out the effect of 1D layered and 2D structures, because magnetic fields are orientation independent which lead to no difference among the null vector directions. This characteristic allows for the measurements of smaller subsurface targets; (2) The DTAC method is insensitive to the orientation errors. It is a robust EM null coupling method. Even large orientation errors do not affect the measured target responses, when a reference frequency and one or more data frequencies are used; (3) The vertical-array DTAC method is effective in reducing the geologic noise and insensitive to the surface interference, e.g., fences, vehicles, power line and buildings; (4) The DTAC method is a high-resolution EM sounding method. It can distinguish the depth and orientation of subsurface targets; (5) The vertical-array DTAC method can be adapted to a variety of rapidly moving survey applications. The transmitter moment can be scaled for effective study of near-surface targets (civil engineering, water resource, and environmental restoration) as well as deep targets (mining and other natural-resource exploration).

In this thesis, four studies using different geophysical electromagnetic methods are presented. In the first study dealing with airborne measurements, the noise response due to the rotation of the aircraft and the aircraft itself as a metallic conductive body on the Earth's electromagnetic response in very low frequency and low frequency band was investigated. The magnetic fields are independent of the aircraft in the VLF band and part of the LF band. But at higher frequencies (above 100 kHz), the signals are more influenced by the aircraft. The aircraft also generates its own noise frequencies which are mixed with the radio transmitter signals. The second and third studies are applications of radio-, controlled source-magnetotellurics and electrical resistivity tomography methods at a quick-clay landslide site in southwest Sweden. The data are processed and modeled in 2D and 3D, and the models are compared with high-resolution seismic and geotechnical data. The obtained results were further validated and refined by performing synthetic tests in the second study. The third study shows that the 3D models provide larger and more continuous volume of the quick clay structure than traditional 2D models. Both studies have shown that integrated application of geophysical methods for landslides is ideal. Quick clays often overlie the coarse-grained layers showing an increase of resistivity values in the models. In the fourth study, a new audio magnetotelluric data acquisition technique is developed and is named moving magnetotellurics (MMT). In this new technique, the magnetic sensors are placed on the ground and only 15 to 20 minutes data are acquired for each station, which usually is enough to cover the frequency range 30-300 Hz. The new technique is more efficient and convenient than the traditional magnetotelluric method, and test measurements have shown that it is an applicable method in shallow depth studies.

Hydrocarbon deposits in the form of petroleum, natural gas, and natural gas hydrates occur offshore worldwide. Electromagnetic methods that measure the electrical resistivity of sediments can be used to map, assess, and monitor these resistive targets. In particular, quantitative assessment of hydrate content in marine deposits, which form within the upper few hundred meters of seafloor, is greatly facilitated by complementing conventional seismic methods with EM data. The North-East Pacific Time-series Undersea Network Experiment (NEPTUNE) is an underwater marine observatory that provides power and network connection to a host of instruments installed on the seafloor on the Cascadia Margin offshore Vancouver Island. The observatory’s aim is to provide a platform for very long-term studies in which access to data is available on a continuous basis. For this thesis project, a transient dipole-dipole time-domain EM system was constructed and deployed on the NEPTUNE network with the goal of long-term monitoring of a well-studied hydrate deposit in the area. The instrument includes a source transmitter of electrical current and individual receivers to measure small electric field variations. The instrument is powered by the NEPTUNE observatory and data can be collected remotely by connecting to the instrument through the web. Data collected so far from the instrument are consistent with a resistive structure. The best fitting model from 1D inversion is a 36 ± 3 m thick layer of 5.3 ± 0.3 Ωm resistivity, overlaying a less resistive 0.7 ± 0.1 Ωm halfspace. Average hydrate concentration, deduced with the aid of ODP-889 well-log derived Archie’s parameters, is approximately 72% of pore space in the resistive layer, consistent with the very high concentration of gas hydrates (~80%) recovered from seafloor cores. The weekly collection of data from the instrument shows that the resistive structure has changed little since monitoring began in October of 2010.

Hydrocarbon deposits in the form of petroleum, natural gas, and natural gas hydrates occur offshore worldwide. Electromagnetic methods that measure the electrical resistivity of sediments can be used to map, assess, and monitor these resistive targets. In particular, quantitative assessment of hydrate content in marine deposits, which form within the upper few hundred meters of seafloor, is greatly facilitated by complementing conventional seismic methods with EM data. The North-East Pacific Time-series Undersea Network Experiment (NEPTUNE) is an underwater marine observatory that provides power and network connection to a host of instruments installed on the seafloor on the Cascadia Margin offshore Vancouver Island. The observatory’s aim is to provide a platform for very long-term studies in which access to data is available on a continuous basis. For this thesis project, a transient dipole-dipole time-domain EM system was constructed and deployed on the NEPTUNE network with the goal of long-term monitoring of a well-studied hydrate deposit in the area. The instrument includes a source transmitter of electrical current and individual receivers to measure small electric field variations. The instrument is powered by the NEPTUNE observatory and data can be collected remotely by connecting to the instrument through the web. Data collected so far from the instrument are consistent with a resistive structure. The best fitting model from 1D inversion is a 36 ± 3 m thick layer of 5.3 ± 0.3 Ωm resistivity, overlaying a less resistive 0.7 ± 0.1 Ωm halfspace. Average hydrate concentration, deduced with the aid of ODP-889 well-log derived Archie’s parameters, is approximately 72% of pore space in the resistive layer, consistent with the very high concentration of gas hydrates (~80%) recovered from seafloor cores. The weekly collection of data from the instrument shows that the resistive structure has changed little since monitoring began in October of 2010.

A atmosfera, ao lado dos principais gases que a compõe, apresenta em menores concentrações milhares de compostos químicos (orgânicos e inorgânicos) distribuídos nas fases líquidas e gasosa ou no material particulado. Quando esses compostos encontrados no ar apresentam níveis de concentração que os tornam impróprios ou nocivos à saúde humana, aos animais ou vegetais e danosos aos materiais, são considerados poluentes atmosféricos. Neste trabalho, enfatizou-se o estabelecimento de métodos alternativos, eficientes e práticos, para a amostragem de várias espécies que participam dos processos de acidificação da atmosfera, assim corno o desenvolvimento de métodos analíticos baseados em técnicas eletroanalíticas em fluxo como a amperometria e a eletroforese capilar com detecção condutométrica sem contato. Devido a algumas limitações das técnicas de amostragem, explorou-se a alternativa de recorrer a tubos capilares com paredes microporosas, preenchidos com solução adequada à absorção das espécies em pauta, após sua difusão através dos poros da membrana hidrófoba. Assim, construiu-se um coletor por difusão utilizando-se tubo de Teflon®, dentro do qual foi introduzido um feixe de tubos capilares porosos de polipropileno. A união desta técnica de amostragem com a determinação seletiva e quantitativa dos analitos por eletroforese capilar com detecção condutométrica (CE-CCD) possibilitou o desenvolvimento de métodos completos para as seguintes espécies: CH2O coletado em água deionizada, à freqüência de 1 amostra por hora, seguido de derivatização com HSO3- para determinação de fonnaldeído na forma de hidroximetanossulfonato (HMS); HCOOH e H3C2OOH- com o mesmo procedimento de coleta e separação por CE-CCD aplicado na detenninação de CH2O na forma de HMS; e NH3 - coletado em solução de HCl e determinado na forma de NH4+ por CE-CCD. Outra espécie de interesse ambiental é o H2O2, por participar de várias reações de oxidação tanto na fase gasosa corno na fase líquida da atmosfera, contribuindo assim para a acidez da atmosfera. A detenninação analítica do H2O2 foi feita por método FIA amperométrico com eletrodo de gota pendente de mercúrio, adaptando-se célula eletroquímica estacionária ao trabalho em fluxo. Duas formas de coleta de H2O2 na fase gasosa foram desenvolvidas e comparadas: . coleta por difusão - com fluxo de água deionizada pelos feixe de filamentos capilares; nesta aplicação, o feixe foi conectado diretamente à alça de amostragem do injetor, proporcionando determinações on-line\". . amostragem criogênica em dispositivo \"passivo\" - aproveitando o fato conhecido de que a razão H2O:H2O2 da fase gasosa se mantém praticamente inalterada na fase sólida (gelo coletado). Além das determinações de H2O2 na fase gasosa, o método FIA-Amperométrico foi utilizado, em trabalhos realizados em parceria com pesquisadores do IPEN, para determinação dessa espécie em efluentes e água de cultivo do microcrustáceo Daphnia similis após serem irradiados com feixes de elétrons. Paralelamente às pesquisas relacionadas a espécies gasosas, desenvolveu-se metodologia para a determinação de cátions e ânions majoritários em água de chuva, recorrendo à CE-CCD, de modo a oferecer uma alternativa à consagrada técnica da cromatografia de íons, demorada e onerosa. Os estudos iniciais da composição iônica da chuva foram feitos com coletas de água de chuva efetuadas no período de Abril/97 a Março/98. Nesse conjunto de amostras determinou-se as concentrações dos cátions (NH4+, Ca2+, K+ e Na+) e dos ânions (NO3-, SO42- e Cl-), além das usuais medições de pH e condutividade. A Eletroforese Capilar mostrou-se particularmente tàvorável para a determinação dos íons majoritários em água de chuva. Embora fugindo da área ambiental, desenvolveu-se metodologia para determinação de espécies de S(IV) em amostras de vinho, a partir de algumas adaptações de método amperométrico em fluxo desenvolvido no mestrado para análise de sulfito e HMS em água de chuva. Assim, desenvolveu-se três sistemas FIA-Amperométrico com eletrodo de gota pendente de mercúrio distintos, os quais foram utilizados para determinação de HSO3- livre e adutado (na forma de hidroxialcanossulfonatos) e SO2, com auxílio de uma unidade de difusão gasosa. / Alongside with its main components, the atmosphere contains trace amounts of thousands of chemical compounds (organic and inorganic) distributed in the liquid and gaseous phases, as well as in the particulate matter. These species can be considered pollutants when they are encountered at levels capable of generating adverse effects to humans, animals, plants or materials. The aim of this work was to establish alternative, efficient and practical methods for the sampling of several species encountered in the gaseous phase, as well as to develop analytical methods based on electroanalytical flow techniques, such as amperometry and capillary electrophoresis with contactless conductometric detection (CE-CCD). Due to some limitations in the existing sampling techniques, an altemative method based on the diffusion of the analytes through the microporous hydrophobic walls of capillary tube filled with an appropriate absorbent solution, was investigated. The collecting device was assembled using a Teflon® tube wherein a bundle of porous capillary polypropylene tubes was introduced. The coupling of this sampling technique with the selective and quantitative determination of the species by capillary electrophoresis with contactless conductometric detection (CE-CCD) enabled the development of complete analytical protocols for the following species: i) CH2O - collected in deionized water at a frequency of 1 sample/h and derivatized with HSO3- for its determination as hydroxymethanesulfonate (HMS); ii) HCOOH and H3COOH - collected using the same sampling procedure and quantified upon separation by CE-CCD; and iii) NH3 - collected in a HCl solution and deterrnined as NH4+ form. Another species of environmental interest is H2O2, which contributes to the acidity of the atmosphere on account of its involvement in some oxidation process both in the gaseous and liquid phases. The deterrnination of the H2O2 Was carried out using a FIA amperometric method at the hanging mercury drop electrode, in a batch electrochemical cell adapted to function under tlowing conditions. Two sampling procedures for H2O2 in the gaseous phase were developed and compared: . collection by diffusion - from the air into a flow of deionized water within the bundle of capillary filaments, which were, in tum, connected to the sample loop in order to allow on-line deterrninations. · cryogenic, with a \"passive\" sampler - based on the well-known fact that the H2O:H2O2 ratio in the gaseous phase is practically maintained in the solid phase. In addition to these determinations in the gaseous phase and in a partnership with researchers of the IPEN, the FIA-Amperometric method was used for the quantification of H2O2 in effluent and in cultivation water of the microcrustacean Daphnia Similis after irradiation by MeV electron beams. In parallel to the related research, a methodology for the CE-CCD determination of majority cations and anions in rain water was developed. This was proposed as an altemarive method to well-established ion chromatography techniques. Initial studies on the ionic composition of rain were conducted on samples collected between April/97 and March/98, using an automatic collector previously developed. In this set of samples, the concentrations of cations (NH4+, Ca2+, K+ e Na+) and anions (NO3-, SO42- e Cl-) were determined, together with the usual measurements of pH and conductivity. Capillary electrophoresis tumed out to be particularly suitable for the determination of ions in rain water. Although strictly not environrnental in kind, a methodology for determination of S(IV) species in wine samples was implemented by adjusting a previously-developed flow-amperometric method for the analysis of sulfite and HMS in rain water. For this purpose, three distinct FIA-Amperometric systems using a gas diffusion device and the hanging mercury drop electrode were designed, assembled and used for the determination of HSO3- in the free and bound forms (as hydroxyaIkanesulfonates) and SO2.

Uncertainty Quantification (UQ) has been an active area of research in recent years with a wide range of applications in data and imaging sciences. In many problems, the source of uncertainty stems from an unknown parameter in the model. In physical and engineering systems for example, the parameters of the partial differential equation (PDE) that model the observed data may be unknown or incompletely specified. In such cases, one may use a probabilistic description based on prior information and formulate a forward UQ problem of characterising the uncertainty in the PDE solution and observations in response to that in the parameters. Conversely, inverse UQ encompasses the statistical estimation of the unknown parameters from the available observations, which can be cast as a Bayesian inverse problem. The contributions of the thesis focus on examining the aforementioned forward and inverse UQ problems for the low-frequency, time-harmonic Maxwell equations, where the model uncertainty emanates from the lack of knowledge of the material conductivity parameter. The motivation comes from the Controlled-Source Electromagnetic Method (CSEM) that aims to detect and image hydrocarbon reservoirs by using electromagnetic field (EM) measurements to obtain information about the conductivity profile of the sub-seabed. Traditionally, algorithms for deterministic models have been employed to solve the inverse problem in CSEM by optimisation and regularisation methods, which aside from the image reconstruction provide no quantitative information on the credibility of its features. This work employs instead stochastic models where the conductivity is represented as a lognormal random field, with the objective of providing a more informative characterisation of the model observables and the unknown parameters. The variational formulation of these stochastic models is analysed and proved to be well-posed under suitable assumptions. For computational purposes the stochastic formulation is recast as a deterministic, parametric problem with distributed uncertainty, which leads to an infinite-dimensional integration problem with respect to the prior and posterior measure. One of the main challenges is thus the approximation of these integrals, with the standard choice being some variant of the Monte-Carlo (MC) method. However, such methods typically fail to take advantage of the intrinsic properties of the model and suffer from unsatisfactory convergence rates. Based on recently developed theory on high-dimensional approximation, this thesis advocates the use of Sparse Quadrature (SQ) to tackle the integration problem. For the models considered here and under certain assumptions, we prove that for forward UQ, Sparse Quadrature can attain dimension-independent convergence rates that out-perform MC. Typical CSEM models are large-scale and thus additional effort is made in this work to reduce the cost of obtaining forward solutions for each sampling parameter by utilising the weighted Reduced Basis method (RB) and the Empirical Interpolation Method (EIM). The proposed variant of a combined SQ-EIM-RB algorithm is based on an adaptive selection of training sets and a primal-dual, goal-oriented formulation for the EIM-RB approximation. Numerical examples show that the suggested computational framework can alleviate the computational costs associated with forward UQ for the pertinent large-scale models, thus providing a viable methodology for practical applications.

A atmosfera, ao lado dos principais gases que a compõe, apresenta em menores concentrações milhares de compostos químicos (orgânicos e inorgânicos) distribuídos nas fases líquidas e gasosa ou no material particulado. Quando esses compostos encontrados no ar apresentam níveis de concentração que os tornam impróprios ou nocivos à saúde humana, aos animais ou vegetais e danosos aos materiais, são considerados poluentes atmosféricos. Neste trabalho, enfatizou-se o estabelecimento de métodos alternativos, eficientes e práticos, para a amostragem de várias espécies que participam dos processos de acidificação da atmosfera, assim corno o desenvolvimento de métodos analíticos baseados em técnicas eletroanalíticas em fluxo como a amperometria e a eletroforese capilar com detecção condutométrica sem contato. Devido a algumas limitações das técnicas de amostragem, explorou-se a alternativa de recorrer a tubos capilares com paredes microporosas, preenchidos com solução adequada à absorção das espécies em pauta, após sua difusão através dos poros da membrana hidrófoba. Assim, construiu-se um coletor por difusão utilizando-se tubo de Teflon®, dentro do qual foi introduzido um feixe de tubos capilares porosos de polipropileno. A união desta técnica de amostragem com a determinação seletiva e quantitativa dos analitos por eletroforese capilar com detecção condutométrica (CE-CCD) possibilitou o desenvolvimento de métodos completos para as seguintes espécies: CH2O coletado em água deionizada, à freqüência de 1 amostra por hora, seguido de derivatização com HSO3- para determinação de fonnaldeído na forma de hidroximetanossulfonato (HMS); HCOOH e H3C2OOH- com o mesmo procedimento de coleta e separação por CE-CCD aplicado na detenninação de CH2O na forma de HMS; e NH3 - coletado em solução de HCl e determinado na forma de NH4+ por CE-CCD. Outra espécie de interesse ambiental é o H2O2, por participar de várias reações de oxidação tanto na fase gasosa corno na fase líquida da atmosfera, contribuindo assim para a acidez da atmosfera. A detenninação analítica do H2O2 foi feita por método FIA amperométrico com eletrodo de gota pendente de mercúrio, adaptando-se célula eletroquímica estacionária ao trabalho em fluxo. Duas formas de coleta de H2O2 na fase gasosa foram desenvolvidas e comparadas: . coleta por difusão - com fluxo de água deionizada pelos feixe de filamentos capilares; nesta aplicação, o feixe foi conectado diretamente à alça de amostragem do injetor, proporcionando determinações on-line\". . amostragem criogênica em dispositivo \"passivo\" - aproveitando o fato conhecido de que a razão H2O:H2O2 da fase gasosa se mantém praticamente inalterada na fase sólida (gelo coletado). Além das determinações de H2O2 na fase gasosa, o método FIA-Amperométrico foi utilizado, em trabalhos realizados em parceria com pesquisadores do IPEN, para determinação dessa espécie em efluentes e água de cultivo do microcrustáceo Daphnia similis após serem irradiados com feixes de elétrons. Paralelamente às pesquisas relacionadas a espécies gasosas, desenvolveu-se metodologia para a determinação de cátions e ânions majoritários em água de chuva, recorrendo à CE-CCD, de modo a oferecer uma alternativa à consagrada técnica da cromatografia de íons, demorada e onerosa. Os estudos iniciais da composição iônica da chuva foram feitos com coletas de água de chuva efetuadas no período de Abril/97 a Março/98. Nesse conjunto de amostras determinou-se as concentrações dos cátions (NH4+, Ca2+, K+ e Na+) e dos ânions (NO3-, SO42- e Cl-), além das usuais medições de pH e condutividade. A Eletroforese Capilar mostrou-se particularmente tàvorável para a determinação dos íons majoritários em água de chuva. Embora fugindo da área ambiental, desenvolveu-se metodologia para determinação de espécies de S(IV) em amostras de vinho, a partir de algumas adaptações de método amperométrico em fluxo desenvolvido no mestrado para análise de sulfito e HMS em água de chuva. Assim, desenvolveu-se três sistemas FIA-Amperométrico com eletrodo de gota pendente de mercúrio distintos, os quais foram utilizados para determinação de HSO3- livre e adutado (na forma de hidroxialcanossulfonatos) e SO2, com auxílio de uma unidade de difusão gasosa. / Alongside with its main components, the atmosphere contains trace amounts of thousands of chemical compounds (organic and inorganic) distributed in the liquid and gaseous phases, as well as in the particulate matter. These species can be considered pollutants when they are encountered at levels capable of generating adverse effects to humans, animals, plants or materials. The aim of this work was to establish alternative, efficient and practical methods for the sampling of several species encountered in the gaseous phase, as well as to develop analytical methods based on electroanalytical flow techniques, such as amperometry and capillary electrophoresis with contactless conductometric detection (CE-CCD). Due to some limitations in the existing sampling techniques, an altemative method based on the diffusion of the analytes through the microporous hydrophobic walls of capillary tube filled with an appropriate absorbent solution, was investigated. The collecting device was assembled using a Teflon® tube wherein a bundle of porous capillary polypropylene tubes was introduced. The coupling of this sampling technique with the selective and quantitative determination of the species by capillary electrophoresis with contactless conductometric detection (CE-CCD) enabled the development of complete analytical protocols for the following species: i) CH2O - collected in deionized water at a frequency of 1 sample/h and derivatized with HSO3- for its determination as hydroxymethanesulfonate (HMS); ii) HCOOH and H3COOH - collected using the same sampling procedure and quantified upon separation by CE-CCD; and iii) NH3 - collected in a HCl solution and deterrnined as NH4+ form. Another species of environmental interest is H2O2, which contributes to the acidity of the atmosphere on account of its involvement in some oxidation process both in the gaseous and liquid phases. The deterrnination of the H2O2 Was carried out using a FIA amperometric method at the hanging mercury drop electrode, in a batch electrochemical cell adapted to function under tlowing conditions. Two sampling procedures for H2O2 in the gaseous phase were developed and compared: . collection by diffusion - from the air into a flow of deionized water within the bundle of capillary filaments, which were, in tum, connected to the sample loop in order to allow on-line deterrninations. · cryogenic, with a \"passive\" sampler - based on the well-known fact that the H2O:H2O2 ratio in the gaseous phase is practically maintained in the solid phase. In addition to these determinations in the gaseous phase and in a partnership with researchers of the IPEN, the FIA-Amperometric method was used for the quantification of H2O2 in effluent and in cultivation water of the microcrustacean Daphnia Similis after irradiation by MeV electron beams. In parallel to the related research, a methodology for the CE-CCD determination of majority cations and anions in rain water was developed. This was proposed as an altemarive method to well-established ion chromatography techniques. Initial studies on the ionic composition of rain were conducted on samples collected between April/97 and March/98, using an automatic collector previously developed. In this set of samples, the concentrations of cations (NH4+, Ca2+, K+ e Na+) and anions (NO3-, SO42- e Cl-) were determined, together with the usual measurements of pH and conductivity. Capillary electrophoresis tumed out to be particularly suitable for the determination of ions in rain water. Although strictly not environrnental in kind, a methodology for determination of S(IV) species in wine samples was implemented by adjusting a previously-developed flow-amperometric method for the analysis of sulfite and HMS in rain water. For this purpose, three distinct FIA-Amperometric systems using a gas diffusion device and the hanging mercury drop electrode were designed, assembled and used for the determination of HSO3- in the free and bound forms (as hydroxyaIkanesulfonates) and SO2.

京都大学 / 0048 / 新制・課程博士 / 博士(工学) / 甲第21089号 / 工博第4453号 / 新制||工||1692(附属図書館) / 京都大学大学院工学研究科都市社会工学専攻 / (主査)教授 小池 克明, 教授 立川 康人, 准教授 後藤 忠徳 / 学位規則第4条第1項該当 / Doctor of Philosophy (Engineering) / Kyoto University / DFAM

O presente trabalho apresenta estudos espectrofotométricos relacionados à autoxidação dos complexos de Cu(II), Ni(II) e Co(II)/tetraglicina induzida por sulfito. Nossos estudos verificaram que a autoxidação de Cu(II)/tetraglicina (1,0x10-3 mol L-1) em pH = 9,0 (tampão borato) é afetada pela presença de traços de Ni(II) ou Co(II). Na ausência de Ni(II) ou Co(II), a reação é muito ineficiente e lenta com períodos de indução longos (aproximadamente 4 h). Ni(II) ou Co( II) em concentrações baixas ( 10-5 - 10-6 mol L-1) afetam significativamente a cinética: o período de indução diminui drasticamente (a menos de 2 s) e a formação de Cu(III) é fortemente acelerada com simultâneo aumento da eficiência da reação. A atividade catalítica e o sinergismo positivo de Co(II) e Ni(II) podem ser explicados pela oxidação mais rápida de Co(II) ou Ni(II)/tetraglicina pelo oxigênio dissolvido. O processo eletroquímico relacionado aos sistemas Cu(II)/Cu(III)/tetraglicina e Ni(II)/Ni(III)/tetraglicina são reversíveis, possibilitando monitorá-los adequadamente mediante o uso da técnica de eletrodo rotativo disco-anel. Entretanto, o sistema Co(II)/Co(III)/tetraglicina é irreversível. Esses estudos mostraram que as espécies de Cu(III) e Ni(III) geradas no eletrodo disco são instáveis nas condições experimentais empregadas. O efeito sinérgico positivo na presença de Ni(II) (que permitiu aumentar a sensibilidade) foi aproveitado para desenvolvimento de método espectrofotométrico e amperométrico simples e sensível para a determinação indireta de sulfito em meio aquoso. O método espectrofotométrico está baseado na medida de absorbância do complexo de Cu(III)/tetraglicina (gerado na presença de sulfito e traços de Ni(II)) em 365 nm. O método amperométrico em análise por injeção em fluxo baseia-se na medida de corrente (0,1 V vs Ag/AgCl) em função da concentração de Cu(III)/tetraglicina gerado quimicamente, na presença de sulfito e traços de Ni(II). Os métodos desenvolvidos foram empregados para a determinação de S(IV), em vinhos e sucos, após a sua extração da amostra acidificada, os resultados obtidos concordaram com aqueles obtidos pelo método iodométrico. / The present work presents spectrophotometric studies related to the sulfite induced autoxidation of Cu(II), Ni(II) and Co(II)/tetraglycine complexes. The sulfite induced autoxidação of Cu(II)/tetraglycine (1.0x10-3 mol L-1) at pH = 9.0 (borate buffer) is affected by the presence of small quantities of the Ni(II) or Co(II). In the absence of added nickel (II) or cobalt (II), the reaction is very inefficient and slow with one large induction period (about 4 h). Trace amounts of Ni(II) or Co(II) (10-5 - 10-6 M) affect the kinetic significantly: the induction period drastically decreases (less than 2 s) and the formation of Cu(III) is strongly accelerated. The effectiveness of Cu(III) formation becomes much higher. The catalytic activity and the positive synergism of Co(II) and Ni(II) may be explained by the faster oxidation of Co(II) or Ni(II)/tetraglycine complexes by dissolved oxygen. The electrochemistry of Cu(II)/Cu(III)/tetraglycine and Ni(II)/Ni(III)/tetraglycine systems are reversible, such as it was possible to monitor them by using the rotating ring-disk electrode technique. However, the Co(II)/Co(III)/tetraglycine system is irreversible. Those studies showed that the Cu(III) and Ni(III) species generated on the disk electrode are unstable in the employed experimental conditions. The positive sinergistic effect in the presence of Ni(II) (which allowed to increase the sensibility) was taken in advantage for development of one simple and sensitive spectrophotometric and amperometric method for indirect determination of sulfite in aqueous medium. The spectrophotometric method is based on the absorbance measurement of the Cu(III)/tetraglicyne complex (generated in the presence of sulfite and small quantities of Ni(II)) at 365 nm. The amperometric method by flow injection analysis is based on the current measurement (0.1 V vs Ag/AgCl) as function of Cu(III)/tetraglycine concentration chemically generated, in the presence of sulfite and Ni(II). The methods were employed for the determination of S(IV), in wines and juices, after its extraction from acidified samples and the results were in agreement with those obtained by the iodometric procedure.

Nesta pesquisa foram realizados levantamentos geofísicos utilizando os métodos eletromagnético indutivo - EMI (equipamento EM38) e GPR - Ground Penetrating Radar, visando localizar redes de interferências, tais como, tubulações metálicas, cabos elétricos e conduítes de plástico instalados nas linhas 6 e 7 do Sítio Controlado de Geofísica Rasa do IAG/USP. Os dados EMI foram afetados pelo drift instrumental devido à variação de temperatura. A sua correção foi efetiva por meio do uso de uma função quadrática, realçando os alvos mais profundos. A aquisição em distância permitiu detectar alvos metálicos no subsolo com boa precisão e a aquisição em tempo permitiu fazer um mapeamento regional de alvos metálicos no subsolo. Os melhores resultados foram obtidos com a aquisição em distância, com os sensores posicionados a 10 cm de altura, devido às anomalias ficarem mais nítidas, onde a influência da condutividade do background foi reduzida. Os perfis GPR 2D obtidos com a antena de 400 MHz permitiram detectar os alvos até 1 m de profundidade e com a antena de 200 MHz foi possível detectar quase todos os alvos metálicos e não-metálicos instalados nas linhas estudas do SCGR. Para o GPR quase-3D, na forma de depth slices, foram importantes para estimar as dimensões dos alvos e melhorar a visualização dos resultados. Os resultados obtidos com os métodos EMI e GPR são complementares, sendo ambos recomendados no mapeamento de interferências no subsolo, tendo aplicações diretas nas áreas de planejamento urbano e infra-estrutura nos grandes centros urbanos. / This research was conducted geophysical surveys using inductive electromagnetic - IEM (EM38 equipment) and GPR - Ground Penetrating Radar methods, to locate network interference, such as metal pipes, electric cables and plastic conduit installed in lines 6 and 7 of test site of the IAG/USP (SCGR). IEM data were affected by instrumental drift due to temperature variation. The correction was effective through the use of a quadratic function, highlighting the deeper targets. The acquisition targets identified in the distance underground metal with good accuracy and acquisition time allowed to make a survey of regional targets metal underground. The best results were obtained with the acquisition in distance with the sensors placed at 10 cm in height, due to deficiencies become more clear, where the influence of the background conductivity was reduced. The 2D GPR profiles obtained with the antenna of 400 MHz to detect the target by 1 m depth and the antenna of 200 MHz was possible to detect almost all metal targets and non-metallic lines installed in the study SCGR. GPR to the quasi-3D in the form of depth slices, were important for estimating the size of the targets and improve the visualization of results. The results obtained with the IEM and GPR methods are complementary, and both are recommended in mapping interference underground, with direct applications in the areas of urban planning and infrastructure in urban centers.