• Refine Query
  • Source
  • Publication year
  • to
  • Language
  • 20
  • Tagged with
  • 20
  • 20
  • 20
  • 20
  • 3
  • 3
  • 3
  • 3
  • 2
  • 2
  • 2
  • 2
  • 2
  • 2
  • 2
  • About
  • The Global ETD Search service is a free service for researchers to find electronic theses and dissertations. This service is provided by the Networked Digital Library of Theses and Dissertations.
    Our metadata is collected from universities around the world. If you manage a university/consortium/country archive and want to be added, details can be found on the NDLTD website.
11

Lithologic Discrimination And Mapping By Aster Thermal Infrared Imagery

Okyay, Unal 01 August 2012 (has links) (PDF)
In conventional remote sensing, visible-near infrared (VNIR) and shortwave infrared (SWIR) part of the electromagnetic spectrum (EMS) have been utilized for lithological discrimination extensively. Additionally, TIR part of the EM spectrum can also be utilized for discrimination of surface materials either through emissivity characteristics of materials or through radiance as in VNIR and SWIR. In this study, ASTER thermal multispectral infrared data is evaluated in regard to lithological discrimination and mapping through emissivity values rather than conventional methods that utilize radiance values. In order to reach this goal, Principle Component Analysis (PCA) and Decorrelation Stretch techniques are utilized for ASTER VNIR and SWIR data. Furthermore, the spectral indices which directly utilize the radiance values in VNIR, SWIR and TIR are also included in the image analysis. The emissivity values are obtained through Temperature-Emissivity Separation (TES) algorithm. The results of the image analyses, except spectral indices, are displayed in RGB color composite along with the geological map for visual interpretation. The results showed that utilizing emissivity values possesses potential for discrimination of organic matter bearing surface mixtures which has not been possible through the conventional methods. Additionally, PCA of emissivity values may increase the level of discrimination even further. Since the emissivity utilization is rather unused throughout in literature and new, further assessment of accuracy is highly recommended along with the field validations.
12

Modeling Groundwater Flow In A Raw Material Site Of A Cement Factory,kocaeli-darica,turkey

Isikli, Yeliz 01 December 2003 (has links) (PDF)
An areal numerical simulation has been carried out to investigate effects of below-sea-level (BSL) excavation in the raw material site of a cement factory in Turkey. A finite element model (585 nodes with 534 elements) is formed to solve for the head distribution in the quarry site upon quarry operation planned to be implemented in the near future. The model is calibrated to the field conditions and appropriate boundary conditions and the physical parameters are obtained to be used in future prediction studies. After a successful calibration the model is run to estimate the water levels and the discharge rates required during below sea level quarry operations. Above sea level (ASL) and below sea level (BSL) operations are simulated and water level contour maps are obtained both for above sea level (ASL) production for the 2000-2030 period, and for each BSL (-10m, -20m, -30m) production periods, which would totally take 13 years. Estimation show that the proposed model runs properly and it calculates the water levels and discharge rates accurately for probable future quarry operations. It is clear that quarry operations would not create a serious problem in terms of water discharge from the quarry site.
13

Polymer/oil Relative Permeabilities In Carbonate Reservoirs

Cankara, Ilker 01 February 2001 (has links) (PDF)
In the history of a reservoir, after the period of primary production, about 30 to 40%, of the original oil in place may be produced using a secondary recovery mechanism. Polymer injection, which is classified as a tertiary method, can be applied to the remaining oil in place. In this thesis, oil/water relative permeabilities, effect of polymer injection on end point relative permeabilities and residual oil saturations in heterogeneous carbonate reservoirs were investigated. Numereous core flood experiments were conducted on different heteroegneous carbonate cores taken from Midyat Formation. Before starting the displacement experiments, porosity, permeability and capillary pressure experiments were performed. The heterogeneity of the cores are depicted from thin sections. Besides the main aim stated above, effect of flow rate and fracture presence on end point relative permeability and on residual oil saturation and were investigated. According to the results of the displacement tests, end point hexane relative permeability increased when polymer solution was used as the displacing phase.Besides, end point hexane relative permeability increased with polymer injection and fracture presence.
14

Gis Based Assessment Of Excavation Difficulty By Tbm-epb Along Mecidiye - Tandogan Segment Of The Tandogan - Kecioren Metro Tunnel

Ozbas, Bengi 01 September 2007 (has links) (PDF)
Tunnel structures are important investments especially for urban areas. Ke&ccedil / i&ouml / ren - Tandogan metro alignment is one of those investments executed by Ankara Metropolitan Municipality. The purpose of this research is to evaluate Tunnel Boring Machine (Earth Pressure Balance type) (TBM-EPB) performance within different lithological units encountered along Tandogan -Mecidiye segment of the Ke&ccedil / i&ouml / ren - Tandogan metro tunnel. The evaluation is based on the data obtained from traditional site investigation methods, statistical approaches and Geographic Information Systems (GIS). Complex geological and hydrogeological conditions are found to be effective in the advancement of a TBM implemented in tunnel boring works. A good understanding of the geology is essential in such cases. Available field (in-situ) and laboratory tests have been used in order to determine geological, hydrogeological and geotechnical properties of the metro tunnel alignment. Advancements in the tunnel boring process also proved that hydrogeological conditions are effective on the performance of TBM so related data are considered carefully while preparing cross-section layers and calculating weights in order to display the distribution of excavation difficulty classes through the tunnel alignment.
15

Hyperspectral Image Processing Of Eo-1 Hyperion Data For Lithological And Mineralogical Mapping

San, Bekir Taner 01 September 2008 (has links) (PDF)
Hyperspectral data is a powerful tool for mineral explorations and lithological discriminations. EO1-Hyperion is a space borne hyperspectral system for hyperspectral imaging which is capable of 220 spectral image channels within the range of 400 to 2500 nm wavelengths. It has advantages over airborne systems such as data cost and coverage area. Although it has many advantages, much more uncertainty exists in application period, of which this uncertainty does exist in all processing stages starting from the data preparation to the end of analysis stages. The aim of this thesis is to state the potential use of Hyperion data for lithological and mineralogical discriminations to further develop new hyperspectral image processing approach, and to improve existing preprocessing method in literature. The proposed algorithm is mainly based on atmospheric corrections and cross track illumination correction of Hyperion data. In order to achieve this, two test sites were selected. Site 1 located on the Central Anatolia, (Ekecek test site) is used for lithological discrimination and Site 2 located on West Anatolia (Biga test site) is used for mineralogical discrimination. The obtained results were compared and assessed with the field verifications, spectral measurements and existing spectral libraries. In the end of the study it is found that when proposed approach is followed hyperspectral data is proven to be a useful tool for mineralogical discrimination in mono minerallic outcrops and valuable for lithological mapping in relatively homogenous un-covered outcrops.
16

Engineering Geological Characterization Of The Tuffite Member Of Hanc&amp / #272 / l&amp / #272 / Formation, Cayyolu, Ankara

Fersoy, Cagla 01 December 2008 (has links) (PDF)
Along NS trending road cut between &Ccedil / ayyolu and incek, relatively thick tuffite layer of the Han&ccedil / ili formation has been exposed. It is alternating with other lacustrine deposits such as clayey limestone, marl, siltstone and mudstone. These units unconformably overlie the Mesozoic basement limestones of Akbayir formation. The illite rich tuffite consists of glass shards tridymite, biotite, quartz and plagioclase. It has a persistent areal extend and forms the foundation of the residential buildings at several localities. In this thesis, it is aimed to assess the engineering geological properties of the tuffite layer and to investigate its suitability as a foundation material. In order to accomplish this task, field studies and laboratory tests were conducted. Field studies involve detailed site geological observation. Laboratory studies include tests to investigate mechanical, physical and mineralogical properties of the tuffite. v Analyses revealed very weak nature of tuffite with strength values ranging between 0.1 MPa and 1.00 MPa. The tuffite is characterized with very high effective porosity (43.3%) and very low dry and saturated densities (1.19 Mg/m3 and 1.62 Mg/m3, respectively). The slake-durability tests yield medium durability. The durability index of tuffite is rated as very poor. Considering index properties and the durability assessment it is concluded that tuffite serves as a poor foundation material.
17

Artificial Recharge Of Groundwater In Kucuk Menderes River Basin, Turkey

Peksezer, Ayse 01 March 2010 (has links) (PDF)
K&uuml / &ccedil / &uuml / k Menderes River Basin located in western Turkey has been facing continuous groundwater level decreases for the past 30 years. In dry periods, irrigation demand is completely met by pumping from groundwater system, which reduces water levels significantly. This provides enough storage to be recharged in wet seasons when streams are running. However, increased runoff in wet season are not utilized neither for irrigation nor for recharge and lost to the Aegean Sea without being infiltrated. Hence, surface artificial recharge methods can be useful to collect excess water in recharge basins, thus allowing infiltration to increase groundwater storage in wet seasons to be later utilized in dry seasons. A 2-D groundwater model is set up by using SEEP/W software. The material functions and parameters used in the model for saturated/ unsaturated conditions are taken from previous studies. Calibration was done to check the accuracy of input data and to control the validity of model. The amount of excess water that will be collected in recharge basins was estimated from flood frequency analysis. Concerning different probabilities, different scenarios were simulated to observe the increase in groundwater levels. Simulation results suggest that significant increase in groundwater storage could be achieved by applying artificial recharge methods. In addition to recharge basins, to reinforce the effect of artificial recharge, simulations were repeated with the addition of an underground dam at downstream side of the basin. Simulation results indicate that the increase in groundwater storage is not sufficient to warrant construction of the underground dam.
18

Effect Of Foundation Rigidity On Contact Stress Distribution In Soils With Variable Strength / Deformation Properties

Cekinmez, Zeynep 01 January 2010 (has links) (PDF)
In this study, a typical mat foundation and structural loading pattern is considered. Three dimensional finite element analyses, PLAXIS 3D, is performed to determine the soil / foundation contact stress distribution, settlement distribution, distribution of modulus of subgrade reaction as a function of column spacing, stiffness of the soil and thickness of the foundation. A parametric study is performed to demonstrate the dependence of those distributions on various parameters. Moreover, a relationship between size of the foundation, deformation modulus of foundation soil and modulus of subgrade reaction is proposed. Depending on the variations in those parameters, obtained shear force and bending moment distributions are compared. Consistency between the resulting shear forces and bending moments of a typical foundation, modeled in two different three dimensional finite element programs, PLAXIS 3D and SAP 2000, is discussed. It is found that the variation in the aforementioned parameters cause different influences on contact stress distribution, settlement distribution, distribution of modulus of subgrade reaction. The importance of those variations in beforementioned parameters, under different situations is discussed. A relationship between modulus of subgrade reaction and deformation modulus of foundation soil is proposed.
19

Geographical Information Systems Based Microzonation Map Of Eskisehir Downtown Area

Kolat, Cagil 01 September 2004 (has links) (PDF)
The purpose of this study is to prepare a geotechnical microzonation map regarding the suitability of the residential areas in EskiSehir downtown area. In order to obtain the microzonation map, Geographical Information Systems (GIS) based Multicriteria Decision Analysis (MCDA) is used. For this analysis, the slope, flood susceptibility, soil, depth to groundwater table, swelling potential and liquefaction potential layers are prepared. The weight values to the layers and rank values to the classes of each layer are assigned by applying Simple Additive Weighting (SAW) and Analytical Hierarchical Process (AHP) methods. Two geotechnical microzonation maps are obtained as outputs of these methods. The study area is categorized into three different zones regarding the foundation suitability of residential areas as: (1) Areas suitable for settlement / (2) Provisional settlement areas / (3) Areas requiring detailed geotechnical investigations. The maps prepared using SAW and AHP methods are found to be consistent with each other. The geotechnical microzonation map prepared using AHP method is recommended as the final map of the study area.
20

Genetic Investigation And Comparison Of Kartaldag And Madendag Epithermal Gold Mineralization In Canakkale-region, Turkey

Unal, Ezgi 01 September 2010 (has links) (PDF)
This thesis study is concerned with the genetic investigation of two epithermal gold deposits (Madendag and Kartaldag) in &Ccedil / anakkale, NW Turkey. The methodology comprises field and integrated laboratory studies including mineralogic-petrographic, geochemical, isotopic, and fluid inclusion analysis. Kartaldag deposit, hosted by dacite porphyry, is a typical vein deposit associated with four main alteration types: i) propylitic, ii) quartz-kaolin, iii) quartz-alunitepyrophyllite, iv) silicification, the latter being characterized by two distinct quartz generations as early (vuggy) and late (banded, colloform). Primary sulfide minerals are pyrite, covellite and sphalerite. Oxygen and sulfur isotope analyses, performed on quartz (&delta / 18O: 7.93- 8.95 &permil / ) and pyrite (&delta / 34S: -4.8 &permil / ) separates, suggest a magmatic source for the fluid. Microthermometric analysis performed on quartz yield a temperature range of 250-285 &ordm / C, and 0-1.7 wt % NaCl eqv. salinity. Madendag deposit, hosted by micaschists, is also vein type associated with two main alteration types: illite and kaolin dominated argillization and silicification, characterized by two distinct quartz phases as early and late. Oxygen isotope analyses on quartz (&delta / 18O: 9.55-18.19 &permil / ) indicate contribution from a metamorphic source. Microthermometric analysis on quartz yield a temperature range of 235-255 &ordm / C and 0.0-0.7 wt % NaCl eqv. salinity. The presence of alunite, pyrophyllite and kaolinite, vuggy quartz and covellite suggest a high-sulfidation epithermal system for Kartaldag. On the other hand, Madendag is identified as a low- sulfidation type owing to the presence of neutral pH clays and typical low temperature textures (e.g. colloform, comb, banded quartz).

Page generated in 0.3136 seconds