Spelling suggestions: "subject:"geophysical"" "subject:"eophysical""
191 |
Casting Identities in Central Seclusion : Aspects of non-ferrous metalworking and society on Gotland in the Early Medieval PeriodGustafsson, Ny Björn January 2013 (has links)
The aim of this thesis has been to investigate and interpret late Iron Ageand Early Medieval traces of non-ferrous metalworking on the islandGotland, Sweden. Gotland was not, based on the archaeological record, anintegrated part of the common Scandinavian culture. Instead a local,endemic cultural expression had developed; a seclusion which lasted forcenturies despite the islands central position in the Baltic Sea. In thepast, key elements for the understanding of local settlement- and burialpractices as well as the local material culture were mainly recovered andreported by local farmers. A specific category of such finds – so-called‘bronze slag’ is discussed and partly reinterpreted in the first study ofthis thesis. Two further studies treat different aspects of metalworkingand metalworkers – one discusses common archaeological notions ofScandinavian workshops, production sites and metalworkers from a criticalperspective while the other mainly focuses on the Gotlandic finds frommetal-detector surveys carried out over the last 35 years. Based on whereand to which extent, both from a quantitative and a qualitative point ofview, these finds occur a hierarchical classification into four sub groupsis presented – ordinary farm sites with traces of non-ferrous metalworking,workshop sites, potential workshop sites and last, extrovert harboursettlements. A fourth study presents an attempt to evaluate the usefulnessof magnetometry in delimiting extant traces of high-temperature crafts,such as metalworking. The last study of the thesis presents an attempt touse trace elements analysis of skeletal lead in human bone to identifypotential non-ferrous metalworkers. As the wearing of endemic Gotlandic jewellery appears to have been centralin the manifestation of the local identity it is argued that themetalworking artisans played a crucial role in defining how this identitywas signalled and displayed via the jewellery and dress-related metalobjects. It is further suggested that these artisans might have played animportant role in upholding the local economy before the advent of localminting. / <p>At the time of the doctoral defense, the following paper was unpublished and had a status as follows: Paper 5: Manuscript.</p>
|
192 |
An integrated geophysical program for sulfide exploration at Ham Nord, Quebec/Jihad, Abakoyas January 1974 (has links)
No description available.
|
193 |
The Schlumberger Array in geophysical prospection for archaeologyGaffney, Christopher F. January 1990 (has links)
The Schlumberger array, or Schlumberger, was one of the first resistance arrays to be used to detect buried archaeological features. The early work used fixed probes and widely spaced traverses. Recent simulation work, ýhowever, suggested that the array should give improved resolution and depth penetration over the Twin-Probe array. This thesis is an attempt to operationalise the Schlumberger for use in archaeological prospection. This has been achieved via a co-ordinated use of laboratory simulation and-field studies. Initial fieldwork in England suggested. that the. - use of point electrodes created response patterns that were dependent upon the relative direction of linear targets. This was verified using a simulation tank modified to represent field procedure. The recognition of this response, therefore, required each survey area to be surveyed twice. The re-survey requires the two current probes to be positioned at right angles to the original survey points. The Schlumberger was then used in a battery of methods to investigate the problem of the archaeological interpretation of- small, discrete scatters of ceramic sherds that cover the landscape in Greece. The research has indicated a variation of intra-site patterning that may be significant to the function of these sites. Overall, the results suggest that the relationship between the 'site' and its environment is a complex one, one that can be oversimplified when the ceramic evidence is viewed in isolation. The Schlumberger indicated possible structural elements within some of these sites.
|
194 |
Tectonic motions and earthquake deformation in Greece from GPS measurementsClarke, Peter John January 1996 (has links)
Sites in a 66-station geodetic network in central Greece have been occupied up to six times since 1989 using GPS surveying, and accurate positions have been computed using fiducially-improved or precise orbits. Site velocities are calculated under the assumption that they are constant with time, after correcting for co-seismic effects, and that the position of the fixed base station (and hence the entire network) may be subject to small errors. Low-order polynomial expressions do not fit the velocity field well. The pattern of observed strain closely resembles that derived from independent geodetic observations made over a hundred-year time-scale. Significant geodetic strain is observed across the Gulf of Korinthos, even after the co-seismic displacement field of the Ms=6.2 1995 Egion earthquake has been removed by forward modelling. Geodetic strain is higher in the western than eastern Gulf, in contrast to the seismic strain which is similar throughout. Seismic strain matches geodetic strain in the east, but a significant deficit of seismic moment exists in the west which may represent a high earthquake hazard in the medium term. The Ms=6.6 1995 Grevena earthquake struck a previously seismically quiet region well covered by a recent triangulation / trilateration survey. Ninety-one points from this network were reoccupied with GPS immediately after the earthquake, and site displacements computed. To invert for the earthquake source parameters from the geodetic displacement field, a novel inversion scheme is used which combines the Monte-Carlo and simplex approaches. A priori parameters are not required, even though the inverse problem is strongly nonlinear. The resulting focal mechanism agrees well with the global CMT solution and locally observed aftershocks, but implies a significantly higher scalar moment than do seismological studies. A network for observing post-seismic deformation has been established, which in view of the low background seismicity seems likely to provide significant results.
|
195 |
High-Resolution Numerical Simulations of Wind-Driven GyresKo, William January 2011 (has links)
The dynamics of the world's oceans occur at a vast range of length scales. Although there are theories that aid in understanding the dynamics at planetary scales and microscales, the motions in between are still not yet well understood. This work discusses a numerical model to study barotropic wind-driven gyre flow that is capable of resolving dynamics at the synoptic, O(1000 km), mesoscale, O(100 km) and submesoscales O(10 km). The Quasi-Geostrophic (QG) model has been used predominantly to study ocean circulations but it is limited as it can only describe motions at synoptic scales and mesoscales. The Rotating Shallow Water (SW) model that can describe dynamics at a wider range of horizontal length scales and can better describe motions at the submesoscales. Numerical methods that are capable of high-resolution simulations are discussed for both QG and SW models and the numerical results are compared. To achieve high accuracy and resolve an optimal range of length scales, spectral methods are applied to solve the governing equations and a third-order Adams-Bashforth method is used for the temporal discretization. Several simulations of both models are computed by varying the strength of dissipation. The simulations either tend to a laminar steady state, or a turbulent flow with dynamics occurring at a wide range of length and time scales. The laminar results show similar behaviours in both models, thus QG and SW tend to agree when describing slow, large-scale flows. The turbulent simulations begin to differ as QG breaks down when faster and smaller scale motions occur. Essential differences in the underlying assumptions between the QG and SW models are highlighted using the results from the numerical simulations.
|
196 |
Seismic and well log attribute analysis of the Jurassic Entrada/Curtis interval within the North Hill Creek 3D seismic survey, Uinta Basin, Utah : case history /O'Neal, Ryan J., January 2007 (has links) (PDF)
Thesis (M.S.)--Brigham Young University. Dept. of Geological Sciences, 2007. / Includes bibliographical references (p. 63-68).
|
197 |
Παλαιογεωγραφική ανάπλαση της περιοχής Πόρου-Μοδιού με εφαρμογή μεθόδων θαλάσσιας γεωφυσικής διασκόπησηςΤσαμπουράκη-Κραουνάκη, Κωνσταντίνα 16 June 2011 (has links)
Οι θαλάσσιες γεωφυσικές μέθοδοι αποτελούν ένα πολύ χρήσιμο μέσο για τη μελέτη της ενάλιας αρχαιολογίας γιατί βοηθούν στη γρήγορη επισκόπηση μεγάλων εκτάσεων του πυθμένα και στον εντοπισμό αρχαιολογικών στόχων που μπορεί να βρίσκονται θαμμένοι κάτω από πετρώματα του πυθμένα.
Επίσης οι θαλάσσιες γεωφυσικές μεθόδοι χρησιμοποιούνται για για τον προσδιορισμό των παλαιοακτών. Με αυτό τον τρόπο μπορει να γίνει ανάπλαση του παλαιόπεριβάλλοντος και της μορφολογίας μιας περιοχής και να συγκεντρωθούν πολύ σημαντικα στοιχεία για τη γεωλογία της περιοχής έρευνας και τον τρόπο με τον οποίο εξελίχθηκε με το πέρασμα των χρόνων.
Η διπλωματική αυτή πραγματεύεται τον τρόπο έρευνας και τις γεωφυσικές μεθόδους που χρησιμοποιήθηκαν για την ανάπλαση των παλαιοακτών στην περιοχή Πόρου- Μοδίου, τα συμπεράσματα που προέκυψαν και οι`αρχαιολογικοί στοχοι οι οποιοι βρέθηκαν. Κατασκευάστηκε ο βυθομετρικός χάρτης της περιοχής, και έγινε η ανάπλαση των εντοπισμένων παλαιοακτών. Τέλος καταγράφηκε ο εντοπισμός ενός μυκηναικου ναυαγίου στο ένα άκρο της νήσου Μόδι. / Marine geophysical methods are a very useful tool for the study of underwater archeology, because they help in quick overview of large areas of the seafloor and identify archaeological objectives which can be found buried under the rock bottom.
Also marine geophysical methods used to determine palaeoshorelines. In this way can be palaeoenvironmental reconstruction and morphology of an area and gather crucial information on the geology of the study area and how they evolved over the years.
This dissertation discusses the research and the geophysical methods which were used for regeneration palaeoshorelines in Poros-Modi and the conclusions and the 'archaeological objectives which were found. Build a bathymetric map of the area, and became the regeneration of localized palaeoshorelines. Finally recorded the location of a Mycenaean wreck at one end of the island of Modi.
|
198 |
Formal Assessment and Measurement of Data Utilization and Value for MinesRogers, William Pratt January 2015 (has links)
Most large contemporary mines already have considerable amounts of data, much of which goes largely unused. The key challenge in big data is increasing data utilization. Much of the data in the mine (not plant) come from a variety of systems, each with different databases and reporting environments. Standard technology deployments create a "silo-ification" of data leading to poor system usage. Through modern server monitoring, data utilization can quantifiably be measured. A host of other quantifiable, often automated approaches, to measuring data use and value can also be incorporated as a means of monitoring value generation. A data valuation tool is presented to measure the data assets at an operation. The Data Value Index (DVI) quantifies business intelligence best practices and user interaction considering managerial flexibility and data utilization rates. The DVI is built considering many case studies of data warehousing at various mining companies, some of which will be presented.
|
199 |
Applying Mine Tailing and Fly Ash as Construction Materials for a Sustainable DevelopmentFeng, Qingming January 2015 (has links)
Geopolymerization has been considered as a new technology to replace the ordinary Portland cement in construction industry. It provides an option to manage the industry waste and byproducts like fly ash, mine tailings. At the same time, the CO₂ emissions can be reduced about 80% compared to that of ordinary Portland cement. The present research includes three main parts. First part is applying mine tailings as construction materials using geopolymerization method. The study is focused on efficiently activating mine tailings, reducing alkali consumption, decreasing curing time and improving compressive strength. We investigate the activation temperature effects, the impacts of additives and effects of forming pressures. The results show that a 40 MPa unconfined compressive strength (UCS) can be achieved with the geopolymerization samples after mine tailings are activated by sodium hydroxide at 170°C for 1 hour with the addition of calcium hydroxide and alkali dissolved aluminium oxide, further compressed with a 10 MPa forming pressure and finally cured at 90°C for 3 days. To elucidate the mechanism for the contribution of additives to geopolymerization, microscopic and spectroscopic techniques including scanning electron microscopy/ energy-dispersive X-ray spectroscopy (SEM/EDX), X-ray diffraction (XRD), and Fourier transform infrared (FTIR) spectroscopy are used to investigate the micro/nanostructure and the elemental and phase composition of geopolymerization specimens. The stress-strain behavior was also characterized. The results shows that the mechanical behavior is similar with that of concrete and the dynamic modulus is 22 GPa, which is comparable with that of concrete. The Young's modulus of geopolymer product was also calculated and the value is in the range of 2.9 to 9.3 GPa. The findings of the present work provide a novel method for the geopolymerization of mine tailings as construction materials. Second section is applying fly ash as a high strength water-resistant construction material. Through the present investigation, a procedure has been studied. The experiment results indicate that the concentration of NaOH, water content, and curing condition can significantly affect the mechanical property of geopolymer matrix. At the same time, the chemical composition, especially the Si/Al ratio and calcium content, is also an important factor during geopolymerization. XRD results show that the amorphous feature can be observed for both high and low calcium fly ash. It is the key of the success of geopolymerizaton due to its high reactivity. XRD, FTIR and SEM tests were performed to study how experiment conditions and the properties of fly ash affect geopolymerization. The obtained compressive strength of the geopolymerization product can reach above 100 MPa. The stress-strain behavior was also characterized. The results shows that the dynamic modulus is 36.5 GPa. The product obtained from the present work shows very high water resistance without losing any compressive strength even after a one month soaking time. Third part is applying the mixture of class C fly ash and mine tailings as construction materials. Through the present investigation, a protocol has been set up. The experiment results of the present work also help set up the working conditions such as activation temperature and time, the concentration of NaOH, the addition of Ca(OH)₂, forming pressure, mine tailing to class C fly ash weight ratio, curing temperature and curing time. To elucidate the mechanism for the contribution of additives to geopolymerization, microscopic and spectroscopic techniques such as SEM/EDX, X-ray diffraction and FTIR spectroscopy were used to investigate the micro/nanostructure and the elemental and phase composition of geopolymerization composite. The obtained compressive strength of the geopolymerization product can reach above 60 MPa. The stress-strain behavior of the geopolymer matrix of the mixture of mine tailing and fly ash were also characterized and the results show that the mechanical behavior is similar to that of concrete with a 24 GPa dynamic modulus. The Young's modulus of geopolymer product was also calculated and the value is in the range of 4.0 to 13.5 GPa. The findings of the present work provide a novel method for the geopolymerization of the mixture of mine tailings and class C fly ash as construction materials, such as bricks for construction and road pavement.
|
200 |
The Echo Cliff structure: identification and analysis of a possible Kansan impact structureLane, Adam Eldon January 1900 (has links)
Master of Science / Department of Geology / Abdelmoneam Raef / Matthew W. Totten / This study examines an ovoid drainage feature southwest of Topeka, Kansas, whose discovery sparked a flurry of activity. Geomicrobial and surface gamma ray surveys indicated possible vertical migration of hydrocarbons, and a ground magnetic survey produced anomalies that resemble the profile of a crater. The area was dubbed the Echo Cliff structure and considered analogous to the Ames structure in Oklahoma, an Ordovician impact structure remarkable for significant hydrocarbon recovery. However, four wells drilled in the area were dry and abandoned. The Echo Cliff structure did yield further indications of its origins by the discovery of possible shocked quartz in drill cuttings from the Ordovician Simpson Group. Our study integrated well log analysis, geophysical modeling, and petrographic analysis to verify or refute the proposed identity of the Echo Cliff structure. Well logs from the area were used to create a structural and stratigraphic cross-section in Petrel® 2016. A gravity survey was conducted in the study area and combined with an aeromagnetic survey, donated by Applied Geophyics, Inc., to use as the basis for geophysical modeling within GM-SYS®. Finally, drill cuttings from the Simpson Group of two wells in the study area were mounted for thin sectioning. These thin sections were examined for planar deformation features, which are indicative of an impact event. The structural and stratigraphic cross sections indicated minimal variation in the subsurface, which is uncharacteristic of an impact event. The GM-SYS® geophysical models seem to indicate that variations in the topography of the Precambrian basement and faulting from the Bolivar-Mansfield Tectonic Zone are responsible for the geophysical anomalies and possibly the current drainage pattern of the study area. Finally, no planar deformation features were observed in any of the examined thin sections. Therefore, there is currently no evidence in support of the claim that the Echo Cliff structure is an impact structure.
|
Page generated in 0.0536 seconds