No description available.

Nickel-base superalloys obtain high temperature mechanical properties through formation of precipitate phases formed via heat treatment. The precipitate microstructure evolves with heat treatment or thermal exposure, which can lead to degrading mechanical properties. This project focuses on the use of electrical resistivity as a non-destructive testing method to monitor the precipitate phase in Waspaloy (a polycrystalline nickel-base superalloy). The evolution of the precipitate microstructure is characterized throughout the volume of the specimens using both small angle neutron scattering (SANS) and ultra small angle X-ray scattering (USAXS) measurements. These measurements are also aided by microscopy and X-ray diffraction measurements.

The integrated use of Electromagnetic Ground Conductivity, Ground Electrical Resistivity and Seismic Refraction geophysics methods was made in Alia valley, Eritrea for the aim of developing a methodology best suited for ground water exploration in hard rock areas with limited professional and financial resources. A total area of 25 square kilometer was covered with the geophysical surveys. The effective use of information from wells and geological information from outcrops and existing literature helped to create a preliminary conceptual hydrogeologic model that in turn provided a general picture of the research site in terms of its groundwater potential and related factors. The optimum configuration of the geophysical methods and their interpretation was researched by the use of synthetic mathematical models and experimental surveys in areas of known hydrogeological characteristics like lithology and depth of water table. Two approximately parallel electromagnetic ground conductivity profile lines crossed the survey area in approximately north-south direction to assess the variation in the electrical conductivity of the major geological structures. Vertical electrical sounding (VES) surveys were conducted close to existing wells with lithological information and at some selected sites. Survey sites for the two dimensional electrical resistivity imaging and the seismic refraction surveys were selected based on the results from the electromagnetic ground conductivity surveys. The formal geophysical surveys results were correlated with nearby boreholes and with each other. The responses of the different geophysical methods for each lithological layer were recognized. In addition, the location and characteristics of the major geological structures of the area were studies based on the information from the geophysical surveys and other available information. At the end of the research, parts of the research area with better groundwater potential were identified. As a result of the research, an efficient and cost effective geophysical approach was developed for groundwater exploration in hard rock areas of Eritrea and similar places of the world. Recommendations were made on the wider and effective use of the approach with due consideration for the limited financial, human resource and material capacities available for ground water exploration in most countries of Africa and other countries of the world.

No description available.

High-resolution electrical-resistivity, seismic-refraction, and seismic-reflection surveys were performed at three locations in the Inner Bluegrass Region of Kentucky along coincident survey lines in order to correlate results and determine which method is most effective at locating karst features in this area. The first two survey locations at Slack’s Cave and the Kentucky Horse Park were chosen in order to investigate known karst features. High and low electrical-resistivity anomalies were correlated to air- and water-filled karst voids, respectively. Seismic velocity anomalies, including parabolic time suppressions, amplitude terminations, and surface-wave backscatters, were also observed and correlated to these karst voids. These findings were applied to a third location along Berea Road in order to investigate undiscovered karst voids. Three seismic targets were selected based on backscatter anomaly locations and were aligned in a northwest trend following the general bedrock dip, joint orientations, and suspected conduit orientation. Overall, the seismic-reflection method provided the highest resolution and least ambiguous results; however, integration of multiple methods was determined to help decrease ambiguities in interpretation created by the inherent non-uniqueness found in the results of each method.

Over 7.8 km of seismic reflection data and 2 km of electrical resistivity data were acquired, processed, and interpreted during this multi-method geophysical study. Objectives included the definition of geologic conditions underlying a contaminant plume in McCracken County, western Kentucky, and the determination of the potential for structural control on the rate and direction of plume migration. Both geophysical methods indicate the presence of multiple high-angle normal faults outlining a series of asymmetric grabens ranging in width from 160 m to almost 300 m and striking between N40°E and N45°E. There was agreement between the two methods on fault location and degree of near-surface offset, with offsets of 1 to 2 m observed at 10 to 20 m below ground surface and 3 to 8 m observed at 20 to 30 m depth. Bedrock displacement was generally 2 to 3 times larger, with offsets of 10 to 26 m observed. The faults appear to have originated in the Paleozoic with predominantly normal reactivation occurring as recently as the Pleistocene. The fault strikes generally approximate the orientation of the northwestern contaminant plume. Observed offset of the Regional Gravel Aquifer may form a preferential flow path for contaminant migration.

Permafrost temperatures were measured by the Geological Survey of Canada (GSC) in 1977-1981 at boreholes along a proposed pipeline route in the southern Yukon. Analysis of climate station records indicate that mean annual air temperatures in the region have since increased by 0.5-1.0˚C. Renewed interest in the pipeline and the need to develop adaptation strategies for existing highway infrastructure have meant that information on permafrost and geotechnical conditions must be updated. To accomplish this goal, a total of eight GSC boreholes ranging in depth from 5-9 m were located, unblocked of ice and instrumented with thermistor cables and data-loggers to permit renewed ground temperature monitoring. Manual temperature measurements were also taken at four other shallow boreholes. Electrical resistivity tomography (ERT) surveys were conducted at each site. MAGTs below 1 m at permafrost sites in the study area range from -0.2˚C to -1.5˚C with permafrost depths greater than 25 m. The permafrost at the study sites can be classified as sporadic discontinuous and extensive discontinuous. Ground temperatures indicate that permafrost can persist under warmer climatic conditions as long as it remains protected by its ecosystem properties. Thermal monitoring for 2011-2012 shows an average increase of 0.5-1.0˚C when compared to the original 1978-1981 ground temperatures. This slow rate of ground warming is mainly attributed to a combination of limited climate change, especially in the south of the study area, ground temperatures close to 0˚C, and the possible disturbance of sites from the removal of vegetation prior to the original measurements being made. ERT surveys conducted at most borehole sites show deeper thaw or taliks where the cleared cut-line used for geophysical work in the 1970s is crossed. These results indicate the impacts of climate change and environmental change in the study area over the past three decades. They appear to match the relatively slow rates of ground warming observed elsewhere in northern Canada where permafrost temperatures are close to 0˚C and where warming also requires changes in latent heat due to internal thaw. TTOP equilibrium modelling suggests that if climate change is responsible for the ground warming, most of the change can be attributed to the step-like MAAT increase that occurred between 1975-1976.

Nickel zinc ferrites (NZF) have been considered as one of the basic components in high frequency electromagnetic applications especially in the field of telecommunications. In the present study, the aim was to produce high quality nickel zinc ferrite ceramics at low soaking temperatures. For this purpose, conventional ceramic manufacturing method based on mixed oxide precursors was followed using calcium fluoride, CaF2, as sintering additive. During the sintering studies, it was noticed that both the microstructure and the electromagnetic properties of the NZF ceramics were modified to a great extent by CaF2. Therefore, material characterization studies involving microstructural, dielectric and magnetic properties were conducted with respect to CaF2 content of ceramics and soak duration. The results showed that due to the presence of CaF2 in ceramics, significant improvements were achieved not only in kinetics of sintering but also in the parameters / DC electrical resistivity, dielectric constant and dielectric loss factor. For example, 1.0 wt% CaF2 added NZF ceramic produced in this study had a DC electrical resistivity of 1011 &amp / #61527 / -cm which was 100,000 times bigger than the one attained in pure NZF ceramic. On the other hand, the dielectric constant exhibited a flat behavior up to 40 MHz with a value around 16. In addition, no resonance peak was observed in dielectric loss factor spectra, and the typical values of dielectric loss factor lied below 0.01. Besides the achievements mentioned, the magnetic properties such as relative magnetic loss factor and hysteresis parameters were also improved.

Landslides have occurred throughout the Holocene geologic epoch and they continue to occur in the Peace River Lowlands of Alberta and British Columbia. This study was conducted to provide an understanding of the processes and extents of one such landslide situated on a major slope at the Town of Peace River, Alberta by means of geophysical techniques with the aim of reducing the geohazard risk to lives and infrastructures. The geophysical characterization involved the acquisition, processing, and joint interpretation of seismic reflection, seismic refraction tomography, vertical seismic profile, and electrical resistivity tomography datasets, thereby providing important information about the subsurface geometry of the landslide, insights into the material properties of the unstable mass in contrast to that of the stable rock, and possible causes of the landslide. This contribution shows that putting considerable efforts into the acquisition and processing of geophysical datasets can yield valuable functional details. / Geophysics

Submitted by Pedro Lemos Camarero null (camarero@folha.com.br) on 2016-05-23T22:57:01Z No. of bitstreams: 1 Análise de integridade Física de Barragens de Terra a partir da integração do método geofísico da eletrorresistividade com ensaios geotécnicos.pdf: 5497568 bytes, checksum: 87ea6f438628a89617555e0a6fb716dc (MD5) / Rejected by Ana Paula Grisoto (grisotoana@reitoria.unesp.br), reason: Solicitamos que realize uma nova submissão seguindo a orientação abaixo: O arquivo submetido não contém a Folha de aprovação. A versão submetida por você é considerada a versão final da dissertação/tese, portanto não poderá ocorrer qualquer alteração em seu conteúdo após a aprovação. Corrija esta informação e realize uma nova submissão contendo o arquivo correto. Agradecemos a compreensão. on 2016-05-25T19:40:42Z (GMT) / Submitted by Pedro Lemos Camarero null (camarero@folha.com.br) on 2016-05-26T17:51:45Z No. of bitstreams: 1 Análise de integridade Física de Barragens de Terra a partir da integração do método geofísico da eletrorresistividade com ensaios geotécnicos.pdf: 5603284 bytes, checksum: 57cc0506d6e9e96bea9a3ed5dc59a2e7 (MD5) / Approved for entry into archive by Ana Paula Grisoto (grisotoana@reitoria.unesp.br) on 2016-05-30T17:17:09Z (GMT) No. of bitstreams: 1 camarero_pl_me_rcla.pdf: 5603284 bytes, checksum: 57cc0506d6e9e96bea9a3ed5dc59a2e7 (MD5) / Made available in DSpace on 2016-05-30T17:17:09Z (GMT). No. of bitstreams: 1 camarero_pl_me_rcla.pdf: 5603284 bytes, checksum: 57cc0506d6e9e96bea9a3ed5dc59a2e7 (MD5) Previous issue date: 2016-04-15 / Dams are structures that dam rivers and streams for a variety of purposes. These structures, often need to be sturdy to withstand the force of the impoundment and the high values of accumulated water load. The constant maintenance of these structures is essential, since a possible accident can lead to damage of catastrophic proportions. This study presents an inexpensive alternative, simple and quick application for investigation of seepage of water in Earth dams, built with distinct loan material. The research methods used were: geotechnical tests as granulometric analysis, determination of the physical indexes of soil, permeability test with permeameter of Guelph and the geophysical method of electric resistivity, from electrical resistivity tomography. At each dam, were acquired three geophysical lines parallel to the longitudinal axis of the dam. The spacing between electrodes was 2m and the array used in the study was Wenner. The results are presented from geophysical images with 2D and 3D electrical resistivity values measured and modeled, where it was possible to identify areas of low relative values of electrical resistivity, interpreted as saturated areas and likely infiltration of the body of the dam. The quantitative data of the Geotechnical testing contribute to greater understanding of the internal water flow. / Barragens são estruturas que represam rios e córregos para diversas finalidades. Essas estruturas, geralmente precisam ser robustas para suportar a força do represamento e os altos valores de carga de água acumulados. A constante manutenção dessas estruturas é imprescindível, uma vez que um acidente eventual pode gerar danos de proporções catastróficas. Esse estudo apresenta uma alternativa barata, de simples e rápida aplicação para investigação de zonas de percolação de água em barragens de terra, construídas com material de empréstimo distintos. Os métodos de investigação utilizados foram: ensaios geotécnicos como análise granulométrica, determinação dos índices físicos do solo, ensaio de permeabilidade com o permeâmetro de Guelph e, o método geofísico da eletrorresistivade, a partir da técnica do imageamento elétrico. Em cada barragem, foram adquiridas três linhas geofísicas paralelas ao eixo longitudinal da barragem. O espaçamento entre eletrodos foi de 2m e o arranjo utilizado no estudo foi o Wenner. Os resultados são apresentados a partir de imagens geofísicas 2D e 3D com valores de resistividade elétrica medida e modelada, onde foi possível identificar zonas de baixos valores relativos de resistividade elétrica, interpretadas como zonas saturadas e de provável infiltração no corpo da barragem. Os dados quantitativos dos ensaios geotécnicos contribuem para maior entendimento do fluxo hídrico interno.