Thèse de doctorat (D.R.M.)--Université du Québec à Chicoutimi, 1998. / Document électronique également accessible en format PDF. CaQCU

Thesis (M.Soc.Sc.)--University of Hong Kong, 1985. / Also available in print.

Thesis (Ph. D.)--University of Alberta, 2010. / Title from pdf file main screen (viewed on June 28, 2010). A thesis submitted to the Faculty of Graduate Studies and Research in partial fulfillment of the requirements for the degree of Doctor of Philosophy in Geophysics, Department of Physics, University of Alberta. Includes bibliographical references.

The Pletersburg greenstone belt Is located In South Africa, about 300 km northeast of Johannesburg. It hosts a significant amount of gold mineralization and just over 1000 kg of gold have been produced from Its various reefs and secondary deposits. The greenstone belt is interpreted as an Archean ophiolite complex. It comprlses a volcano-sedimentary succession (the Pletersburg Group) which Is subdivided Into a basal greenstone sequence, interpreted as oceanic crust, and an upper sedimentary cover sequence. A number of major shear zones, which are thought to represent thrusts that developed during the subduction of the greenstone sequence, form an integral part of the stratigraphy . Four stages of deformation (D₁-D₄) and four phases of metamorphism (H₁-H₄) (three of which are correlatable with the peak stages of deformation) are recognized. The primary gold deposits are all shear zones related. but they are subdivided into greenstone, sedimentation and granIte-hosted types. Geographically, they occur In three distinct goldfields: Eerstellng, Roodepoort and Marbastad. The greenstone-hosted · Plenaar-Doreen shear complex Is In the Eersteiing goldfield and hosts eight gold occurrences. Within the complex, Girlie North Reef is the 640m-long "pay" section of the Girlie North shear zone. This reef is characterized, macroscopically, by a Quartz-carbonate-chlorite-sulphlde assemblage and, mlcroscoplcally, by the presence of tourmaline, arsenopyrlte and Au. Geochemical evidence Indicates that mineralizing fluids were H₂O and CO₂-bearing and rich In S, K and Al. The wall rock alteratlon was Isochemlcal but Is manifest as a change In mineralogy from a hornblende + plagioclase assemblage to an actlnollte/tremollte + Quartz + clay assemblage. This Is best developed In the hangIng wall of the reef and is thought to have been caused by hydrogen ion metasomatism. The Arsenopyrite Reef was one of the main sediment-hosted shear zone gold producers In the Harabastad goldfield. This reef Is Interpreted as the basal margin of a shear zone whose top contact Is probably represented by the Quartz Vein Reef. The shear zone consists predomonantly of quartz and carbonate, and the two "pay" reefs are characterized by tourmallne. arsenopyrite and Au. No wall rock alteration was identified In this study, Based on the mineralogy and geochemical signature of the Girlie Nortn Reef and the Arsenopyrite Reef, It Is proposed that both were formed at the $The Pletersburg greenstone belt Is located In South Africa, about 300 km northeast of Johannesburg. It hosts a significant amount of gold mineralization and just over 1000 kg of gold have been produced from Its various reefs and secondary deposits. The greenstone belt is interpreted as an Archean ophiolite complex. It comprlses a volcano-sedimentary succession (the Pletersburg Group) which Is subdivided Into a basal greenstone sequence, interpreted as oceanic crust, and an upper sedimentary cover sequence. A number of major shear zones, which are thought to represent thrusts that developed during the subduction of the greenstone sequence, form an integral part of the stratigraphy . Four stages of deformation (D₁-D₄) and four phases of metamorphism (H₁-H₄) (three of which are correlatable with the peak stages of deformation) are recognized. The primary gold deposits are all shear zones related. but they are subdivided into greenstone, sedimentation and granIte-hosted types. Geographically, they occur In three distinct goldfields: Eerstellng, Roodepoort and Marbastad. The greenstone-hosted · Plenaar-Doreen shear complex Is In the Eersteiing goldfield and hosts eight gold occurrences. Within the complex, Girlie North Reef is the 640m-long "pay" section of the Girlie North shear zone. This reef is characterized, macroscopically, by a Quartz-carbonate-chlorite-sulphlde assemblage and, mlcroscoplcally, by the presence of tourmaline, arsenopyrlte and Au. Geochemical evidence Indicates that mineralizing fluids were H₂O and CO₂-bearing and rich In S, K and Al. The wall rock alteratlon was Isochemlcal but Is manifest as a change In mineralogy from a hornblende + plagioclase assemblage to an actlnollte/tremollte + Quartz + clay assemblage. This Is best developed In the hangIng wall of the reef and is thought to have been caused by hydrogen ion metasomatism. The Arsenopyrite Reef was one of the main sediment-hosted shear zone gold producers In the Harabastad goldfield. This reef Is Interpreted as the basal margin of a shear zone whose top contact Is probably represented by the Quartz Vein Reef. The shear zone consists predomonantly of quartz and carbonate, and the two "pay" reefs are characterized by tourmallne. arsenopyrite and Au. No wall rock alteration was identified In this study, Based on the mineralogy and geochemical signature of the Girlie Nortn Reef and the Arsenopyrite Reef, It Is proposed that both were formed at the same time. Textural evidence Indicates that tourmaline, arsenopyrite and Au were all very late In the paragenesis of minerallzatlon. The presence of tourmaline also Indicates a probable granite association. It Is proposed that the maln gold mineralizing event was synchronous with the Intrusion of granitoids (and therefore also with (D₁-D₄) and (H₁-H₄) and that most of the Au was derived from felsic magma. Gold was partitioned Into a magmatic hydrothermal fluid and then transported into the greenstone belt as a chlorIde complex. These magmatiC fluids were channelled up shear zones whIch had already been mineralized with a quartz-carbonate-chlorlte - sulphide assemblage by previous metamorphic fluidS. generated during the dynamic (D₂-related) H₂-phase of metamorphism. The Au was then deposIted as the result of a change In a fluid variable, such as temperature, pH, f0₂, or the activity of Cl (some Au may have been transported In a sulphur complex and so the activity of reduced 5 could also have been Important).

Esta tese tem como objetivo a modelagem da degradação de correias em transportadores utilizados em mineração, como função do tempo e de outras covariáveis independentes que fazem parte do processo de mineração e que influenciam no desgaste das mesmas. Para a realização do trabalho, utilizou-se um método dividido em duas etapas: (i) abordagem qualitativa (estudo teórico do tópico degradação de correias e coleta de dados através da técnica de Grupo Focado – GF), para definição de variáveis influentes no desgaste, e (ii) abordagem quantitativa, para obtenção do modelo de degradação das correias, sendo utilizada, no estudo em questão, uma regressão linear múltipla. Como resultado foi possível identificar através da literatura, assim como via GF, que as variáveis ciclo da correia, comprimento e largura da correia, queda do material, limpador de correias (raspadores), taxa de alimentação, granulometria, composto e velocidade da correia impactariam potencialmente na degradação de correias. Já com o uso da regressão múltipla, constatou-se que as mesmas realmente são significativas e influentes, corroborando os dados obtidos via GF. De posse dos modelos de degradação obtidos para cada correia, foi possível elaborar uma proposta de sistemática de gestão da degradação de correias, baseada na comparação da evolução do desgaste real com o previsto, de modo a se detectar possíveis desvios e permitir a elaboração de ações de correção, visando minimizar a degradação acelerada e maximizar a vida útil das correias. Conseguiu-se estimar um ganho financeiro potencial de cerca de R$ 1.132.000,00 por ano, a partir da comparação entre a vida útil calculada pelos modelos de degradação e a vida estimada pela área de manutenção do complexo. / This thesis aims at modelling of the conveyor’s belt degradation used in mining as a function of time and other independent covariate that are part of the mining process and have influence in their wearing. To carry out the research we implemented a method divided in two stages: (i) a qualitative approach (theoretical study of conveyor belts degradation and data collection through Focused Groups – FG) for definition of factors that are influential in the wearing of belts, and (ii) a quantitative approach for obtaining a belts’ degradation model through multiple linear regression. It was possible to identify in the literature and through FG that variables such as belt cycle, belt length and width, material fall, belt cleaner, feed rate, particle size, compound and belt speed could potentially impact on the degradation of belts. Using multiple regression such variables were found to be statistically significant, corroborating the data obtained from FG. With the degradation models obtained for each conveyor belt it was possible to propose a method for the maintenance management of conveyor belts. The method was based on the comparison of real wear versus predicted wear in order to detect possible deviations and to allow the development of correction actions that aim at minimizing accelerated degradation and maximizing the belt’s lifetime. A potential financial gain of approximately R$ 1.132.000,00 per year was estimated comparing the lifetime obtained using the degradation models and the life estimated by the maintenance area of the complex.

Esta tese tem como objetivo a modelagem da degradação de correias em transportadores utilizados em mineração, como função do tempo e de outras covariáveis independentes que fazem parte do processo de mineração e que influenciam no desgaste das mesmas. Para a realização do trabalho, utilizou-se um método dividido em duas etapas: (i) abordagem qualitativa (estudo teórico do tópico degradação de correias e coleta de dados através da técnica de Grupo Focado – GF), para definição de variáveis influentes no desgaste, e (ii) abordagem quantitativa, para obtenção do modelo de degradação das correias, sendo utilizada, no estudo em questão, uma regressão linear múltipla. Como resultado foi possível identificar através da literatura, assim como via GF, que as variáveis ciclo da correia, comprimento e largura da correia, queda do material, limpador de correias (raspadores), taxa de alimentação, granulometria, composto e velocidade da correia impactariam potencialmente na degradação de correias. Já com o uso da regressão múltipla, constatou-se que as mesmas realmente são significativas e influentes, corroborando os dados obtidos via GF. De posse dos modelos de degradação obtidos para cada correia, foi possível elaborar uma proposta de sistemática de gestão da degradação de correias, baseada na comparação da evolução do desgaste real com o previsto, de modo a se detectar possíveis desvios e permitir a elaboração de ações de correção, visando minimizar a degradação acelerada e maximizar a vida útil das correias. Conseguiu-se estimar um ganho financeiro potencial de cerca de R$ 1.132.000,00 por ano, a partir da comparação entre a vida útil calculada pelos modelos de degradação e a vida estimada pela área de manutenção do complexo. / This thesis aims at modelling of the conveyor’s belt degradation used in mining as a function of time and other independent covariate that are part of the mining process and have influence in their wearing. To carry out the research we implemented a method divided in two stages: (i) a qualitative approach (theoretical study of conveyor belts degradation and data collection through Focused Groups – FG) for definition of factors that are influential in the wearing of belts, and (ii) a quantitative approach for obtaining a belts’ degradation model through multiple linear regression. It was possible to identify in the literature and through FG that variables such as belt cycle, belt length and width, material fall, belt cleaner, feed rate, particle size, compound and belt speed could potentially impact on the degradation of belts. Using multiple regression such variables were found to be statistically significant, corroborating the data obtained from FG. With the degradation models obtained for each conveyor belt it was possible to propose a method for the maintenance management of conveyor belts. The method was based on the comparison of real wear versus predicted wear in order to detect possible deviations and to allow the development of correction actions that aim at minimizing accelerated degradation and maximizing the belt’s lifetime. A potential financial gain of approximately R$ 1.132.000,00 per year was estimated comparing the lifetime obtained using the degradation models and the life estimated by the maintenance area of the complex.

Esta tese tem como objetivo a modelagem da degradação de correias em transportadores utilizados em mineração, como função do tempo e de outras covariáveis independentes que fazem parte do processo de mineração e que influenciam no desgaste das mesmas. Para a realização do trabalho, utilizou-se um método dividido em duas etapas: (i) abordagem qualitativa (estudo teórico do tópico degradação de correias e coleta de dados através da técnica de Grupo Focado – GF), para definição de variáveis influentes no desgaste, e (ii) abordagem quantitativa, para obtenção do modelo de degradação das correias, sendo utilizada, no estudo em questão, uma regressão linear múltipla. Como resultado foi possível identificar através da literatura, assim como via GF, que as variáveis ciclo da correia, comprimento e largura da correia, queda do material, limpador de correias (raspadores), taxa de alimentação, granulometria, composto e velocidade da correia impactariam potencialmente na degradação de correias. Já com o uso da regressão múltipla, constatou-se que as mesmas realmente são significativas e influentes, corroborando os dados obtidos via GF. De posse dos modelos de degradação obtidos para cada correia, foi possível elaborar uma proposta de sistemática de gestão da degradação de correias, baseada na comparação da evolução do desgaste real com o previsto, de modo a se detectar possíveis desvios e permitir a elaboração de ações de correção, visando minimizar a degradação acelerada e maximizar a vida útil das correias. Conseguiu-se estimar um ganho financeiro potencial de cerca de R$ 1.132.000,00 por ano, a partir da comparação entre a vida útil calculada pelos modelos de degradação e a vida estimada pela área de manutenção do complexo. / This thesis aims at modelling of the conveyor’s belt degradation used in mining as a function of time and other independent covariate that are part of the mining process and have influence in their wearing. To carry out the research we implemented a method divided in two stages: (i) a qualitative approach (theoretical study of conveyor belts degradation and data collection through Focused Groups – FG) for definition of factors that are influential in the wearing of belts, and (ii) a quantitative approach for obtaining a belts’ degradation model through multiple linear regression. It was possible to identify in the literature and through FG that variables such as belt cycle, belt length and width, material fall, belt cleaner, feed rate, particle size, compound and belt speed could potentially impact on the degradation of belts. Using multiple regression such variables were found to be statistically significant, corroborating the data obtained from FG. With the degradation models obtained for each conveyor belt it was possible to propose a method for the maintenance management of conveyor belts. The method was based on the comparison of real wear versus predicted wear in order to detect possible deviations and to allow the development of correction actions that aim at minimizing accelerated degradation and maximizing the belt’s lifetime. A potential financial gain of approximately R$ 1.132.000,00 per year was estimated comparing the lifetime obtained using the degradation models and the life estimated by the maintenance area of the complex.

Orientador: Robson Pederiva / Dissertação (mestrado) - Universidade Estadual de Campinas, Faculdade de Engenharia Mecânica / Made available in DSpace on 2018-08-16T15:55:46Z (GMT). No. of bitstreams: 1 Santos_BrunoSavioBoghossiandos_M.pdf: 1516247 bytes, checksum: 56409e552f694a7e6380abecffa30505 (MD5) Previous issue date: 2010 / Resumo: O acoplamento entre os movimentos de rotação do braço do tensionador e os movimentos transversais dos tramos de correia adjacentes à polia do tensionador é investigado neste trabalho. As equações de movimento de um sistema composto por três polias, correia serpentina e um autotensionador são derivadas a partir do Princípio de Hamilton. Estas equações formam a base para as análises do equilíbrio e vibração linear. Dois métodos são descritos para a solução das equações do equilíbrio. A solução numérica converte rapidamente e fornece a base para a análise da vibração linear. A solução linear aproximada fornece uma indicação da efetividade do design do tensionador, ou seja, sua capacidade de manter a tensão de tração constante, medida a partir da constante de suporte desenvolvida nesta análise. Uma solução de forma fechada baseada no método de Holzer é proposta para analisar as vibrações livres. Dois loops de iteração são utilizados na solução. Um loop interno para a estrutura cíclica e um loop externo para o tensionador. A principal conclusão deste estudo é que um acoplamento linear existe entre os movimentos de rotação do braço do tensionador e os movimentos transversais dos tramos de correia adjacentes à polia do tensionador e produzem respostas dinâmicas diferentes de quando o mesmo é desconsiderado. Um aplicativo para a implementação do modelo foi desenvolvido em Visual Basic / Abstract: The coupling between the tensioner rotational movement and the transverse movement of the belt spans adjacent to the tensioner pulley is investigated in this study. Hamilton's Principle is used to derive the governing equations of motion which provide the basis for the equilibrium and linear vibration analysis. Two methods are described for solving the equations of equilibrium. The exact, nonlinear, iterative solution converges quickly, and provides the basis for the linear vibration analysis. The approximated solution provides an indication of the system design effectiveness by the tensioner support constant derived in the study. A closed form solution based on the Holzer's method is proposed for solving the linear vibration analysis problem. Two iterations loops are used in the solution. An internal loop for the cyclic structure and an external loop for the tensioner arm. A major conclusion of this study is that linear coupling exists between rotational and transverse vibrations, and often produces different dynamic response than that predicted by ignoring coupling. A software was developed in Visual Basic to implement the model / Mestrado / Mecanica dos Sólidos e Projeto Mecanico / Mestre em Engenharia Mecânica

Orientador: Alfonso Schrank / Dissertação (mestrado) - Universidade Estadual de Campinas, Instituto de Geociencias / Made available in DSpace on 2018-08-06T16:33:27Z (GMT). No. of bitstreams: 1 Spreafico_RicardoRamos_M.pdf: 74748494 bytes, checksum: 5ea89bb7faa599f44ce1b9c5c4dc8024 (MD5) Previous issue date: 2006 / Resumo: A área mineralizada a ouro de Morro da Glória, centro-norte do Quadrilátero Ferrífero, Minas Gerais, contém depósitos hospedados na sequência vulcano-sedimentar do Greenstone Belt Rio das Velhas. Estes depósitos são controlados por estruturas e condições químicas influenciadas pela formação ferrífera bandada (FFB), identificadas em mapeamento geológico de superficie na escala 1: 4000 e em análises petrográficas e de petrotexturas. A FFB está intercalada em meta-basaltos do Grupo Nova Lima, e ambos estão alterados hidrotermalmente. A sericitização é o mais importante processo de alteração e foi principalmente desenvolvido no contato de quartzo-sericita xisto com FFB da Serra do Vum Vum. Nas outras ocorrências de FFB no centro e sul da área, entretanto, a c1oritização é dominante. A carbonatação é sempre subordinada, como um estágio intermediário entre as porções c1oritizada e sericitizada. Estas transformações estão associadas à sulfetação e à mineralização aurífera, assim como ao comportamento estrutural dos litotipos durante os principais eventos deformacionais. Três fases deformacionais são propostas para explicar a evolução estrutural. Uma fase D1, caracterizada por dobras isoc1inais de flanco invertido, com eixos de atitude média 90/37, como parte de zona de cisalhamento dúctil vergente para NNW, no contexto geológico regional. Uma fase O2, caracterizada por dobras desarmônicas, parasíticas, cilíndricas ou suaves, que evidenciam cisalhamento puro confirmado pela orientação de eixo-c de grãos de quartzo de veios recristalizados em O2. A c1ivagem de fratura plano-axial S2 indica deformação sob regime dúctil-rúptil. A fase D3 é evidenciada por falhas inversas com vergência para NW. A entrada de fluidos mineralizantes teria ocorrido durante a fase DI, quando os condutos foram criados como estruturas geradas durante o cisalhamento, na forma de aberturas tensionais, que permitem a passagem de fluidos, os quais reagem com as rochas hospedeiras. Na paragênese do minério predomina a pirita. À medida que a deformação progrediu, os veios e os próprios corpos mineralizados foram paralelizados, estirados e acomodaram a foliação SI. A rotação do pacote de FFB, como um corpo mais rígido, envolvido por basaltos hidrotermalizados, agora transformados em assembléias de xistos, formou a dobra principal que forma a Serra do Vum Vum. Essa rotação leva ao aparecimento de nova estrutura planar, representada pela clivagem de fratura S2 e novas aberturas tensionais. Estas são ocupadas por fluidos, que ainda não deixaram de circular, mas que podem ter natureza um pouco distinta, mais ricos em Cu e Au. O minério é agora formado por abertura na pirita preenchida por calcopirita e ouro (minério de pirita-calcopirita-ouro). No final dos eventos de deformação as estruturas S3 foram formadas, em nível crustal mais superficial e seccionaram os corpos mineralizados. análise das estruturas geológicas feita na área mineralizada do Morro da Glória, em particular, de controles estrutural e químico, ou metalotectos, mostrou o quanto essencial é a FFB para a criação de permeabilidade estrutural, para reações de sulfetação e, juntamente, para precipitação de ouro. Este modelo de redobramento da FFB é muito importante para delinear, em superficie e sub-superfície, a geometria da FFB, hospedeira da mineralização, que é aplicável em prospecção aurífera nessa área e também na exploração regional. O mapeamento de corredores com foliação S: predominante pode direcionar descoberta de zonas de concentração preferencial de ouro durante a fase deformacional D2 / Abstract: The gold mineralized area of Morro da Glória, center-north of Quadrilátero Ferrífero, Minas Gerais, Brasil, contain deposits hosted by the volcano-sedimentary pile of the Rio das Velhas Greenstone BeIt. This deposits are controlled by structures and chemical conditions influenced by banded iron fonnation (FFB), identified in surface geological mapping in scale 1:4000 and studied by petrographic and petrofabric approaches. The FFB is interbeded in metabasalts from Nova Lima Group, and bOth are hydrothennal altered. A sericitization is the main alteration process and was mainly developed on the outer contact of FFB at the Serra do Vum Vum. On others FBB occurrences in central e south of the area, however, the chloritization is dominant. The carbonatization is ever subordinated, as an intermediary stage between the chloritized and the sericitized portions. Those transformations as played major rules even on sulphides and gold mineralization as on the structural behavior during the main deformational events. Three deformational phases are proposed to explain the structural evolution history. A DI phase, characterized by isoclinal folds of inverted limb, with averaged axis climbing of 90/37, as a part of an ductile shear zone verging to NNW, in the broad geological context. A D2 phase, characterized by tuneless, drag, cylindrical or gentle folds, which evidences pure shear confinned by the orientation of c-axis of quartz grains from recristalized veins in D2. The cleavage fracture axial planes S2 indicate deformation under a ductile-ruptile regime. The D3 phase is evidenced by inverse faults verging to NW. The onset of mineralized fluids would be occurred during the DI phase, when the conduits were formed as structures generated during shear, in form of tension gashes, allows the fluids to pass trough and react with host rocks. The ore paragenesys was pyrite droved. As the deformation as increased, the veins and the mineralized bodies stretched, becomes parallel, and accommodates the SI foliation.The rotation of the FF B package, as rigid bodies, enveloped by the hydrothermalized basalts, then transformed in ductile schist assemblages, developed the main fold that fonns the Serra do Vum Vum. This rotation leads to the development of new planar structures, represented by cleavage fractures 82 and new tension gashes. These are drained by fluids, that yet don't stopped to circulate, but can have a little distinct provenance, as it is richer in Cu e Au. Ore is now formed by broken pyrite filled by chalcopyrite and gold drops (pyrite-chalcopyrite-gold ore). Previous pyrite ore was rigid during the D2 ductile event. At the end of deformational events the S3 structures as formed, at most superficial crustallevels and has sectioned the mineralized bodies. The geological structures analysis done at Morro da Glória mineralized area, in particular, from structural and chemical controls, or metalotects, showed as essential is the FFB to allow the creation of structural permeability, the reactions of sulphidation and, besides, the gold precipitation. Also, this standard of refolded FBB is very important to delineate, in surface and underground, the geometry of FFB hosting gold mineralization, which is applicable to gold prospecting on this area but also on regional exploration. Mapping of corridors with dominant S2 foliation can drive to discover zones of preferential gold concentration during the D2 deformational phase / Mestrado / Metalogenese / Mestre em Geociências

Energetic electrons undergo significant flux variations in the Earth’s outer radiation belt, where magnetospheric waves play an important role in changing the energetic electron dynamics. In particular, electromagnetic ion cyclotron (EMIC) waves are suggested to drive efficient pitch angle scattering of relativistic electrons, which results in relativistic electron precipitation into the upper atmosphere. Such precipitation provides an important source of energy input into the upper atmosphere, where precipitating electrons can affect atmospheric chemistry and ionization. However, the quantitative role of EMIC waves in energetic electron precipitation in various regions of the magnetosphere is not fully understood. This dissertation aims to answer outstanding open questions on the characteristics and quantification of EMIC-driven precipitation, such as the spatial extent and the energy range of electron precipitation. The relationship between EMIC waves and electron precipitation is evaluated by analyzing magnetic conjunction events when EMIC waves are detected in the magnetosphere by near-equatorial satellites (Van Allen Probes, GOES) and precipitating electrons are measured by Low-Earth-Orbiting satellites (POES, FIREBIRD). Quasi-linear theory is used to quantify the role of various observed magnetospheric waves (e.g., EMIC waves, plasmaspheric hiss, magnetosonic waves) in the electron precipitation. Several in-depth case analyses show that EMIC waves are the main driver of the observed relativistic electron precipitation, while other waves play a minor role. The precipitation events were clearly identified within L shell of ~7.5, favorably near the dusk and night sectors. The analysis shows that each precipitation event was localized on average spatial scales of ~0.3 L, suggesting that the resonance conditions are satisfied in a very localized region of the magnetosphere. The electron precipitation was observed at the expected relativistic (> ~MeV) energies; however, the minimum energy of efficient electron precipitation was newly found to extend down to at least ~200–300 keV. The quantitative analysis using multi-point measurements combined with theoretical calculations in this dissertation provides a more comprehensive understanding of EMIC-driven precipitation, which is a critical electron loss process in the magnetosphere. Moreover, the results are helpful to improve currently existing models of radiation belt, ring current and atmosphere dynamics, as well as theories of wave-particle interactions.