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  • 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

Evaluation Of Kosovo-artana Concentrator Tailings

Oz, Ekrem Eser 01 May 2011 (has links) (PDF)
In this study, evaluation of Kosovo-Artana Concentrator tailings with flotation and leaching method is aimed. The minerological analysis of sample showed that sphalerite, galena, chalcopyrite and their oxidised forms are the main ore minerals in the sample, while pyrite, illite, quartz, calcite and gypsum are the gangue minerals. The metal contents of the sample are 1.2% Zn, 0.75% Pb, and 0.06% Cu. Flotation tests to produce bulk concentrate of copper-lead and lead-zinc were unsatisfactory. The recovery of the zinc with H2SO4 leaching were conducted both at room temperature and at elevated temperature. The effects of various parameters such as leaching duration, concentration of H2SO4, pulp density and temperature on the zinc metal recovery were examined. The maximum extraction of zinc was 80% and 89% at room temperature and at 80 &deg / C respectively for 120 minutes leaching period.
12

Archaeometric Investigations Of Stone Deterioration In Kalecik (ankara) Castle

Akoglu, Alp Osman 01 February 2012 (has links) (PDF)
Kalecik Castle is an important historical building. However, dacitic building stone sed is deteriorating mainly because of atmospheric conditions. The purpose of this tudy is to understand the deterioration mechanisms affecting the dacitic stones used n the castle&rsquo / s walls. To achieve this purpose various arhaeometrical methods such as etrography, X-ray diffraction analyses, analyses for determining physical poperties density, porosity, and water absorption capacities), ultrasonic velocity easurements and some mechanical tests are used. The results of this study show that the deterioration of Kalecik Castle results mostly rom physical factors such as frost action, wetting and drying and thermal shock. According to the study, chemical and biological factors that may also be an mportant cause of deterioration are negligible in Kalecik Castle&rsquo / s building stones.
13

Coastal Scenic Evaluation By Application Of Fuzzy Logic Mathematics

Ucar, Baris 01 August 2004 (has links) (PDF)
Coastal scenery evaluated by utilization of selected landscape components was subject to fuzzy logic system approach. Based on this methodology, coastal areas were grouped into five classes using the evaluation index D giving the overall result of scenic assessment over the attributes. Within the methodology, public perception surveys from Turkey, UK, Malta, and Croatia were used as a tool for environmental perception in the methodology. The results of the public perception surveys were utilized to obtain the weights of scenic parameters. Public surveys in &Ccedil / irali were related to demographical information of respondents by factorial analysis. A coastal scenic classification curve was obtained for all 86 coastal sites around the world which enabled grouping of the sites in five different classes.
14

Metodika výuky prvouky a vlastivědy regionu na příkladu Rakovnicka / Methodology of Public Administration Display and geography of the region for example Rakovnicko

HLUŠTÍKOVÁ, Petra January 2010 (has links)
My diploma thesis called ``Methodology of General Science and Homeland study of the region in the example of Rakovnicko`` consists of two parts. The first part is theoretical and describes the region of Rakovník from many aspects such as characteristics and structuring of this territory, physical-geographical and socio-economic dates and the nature and landscape protection. The data for the creation of the second practical part are created from the first theoretical part and these are: teaching materials, worksheets, concepts of walks and excursions and methodical book for teachers of primary school of this area.
15

Modeling Neurons That Can Self Organize Into Building Blocks And Hierarchies: An Exploration Based On Visual Systems

Polat, Aydin Goze 01 September 2012 (has links) (PDF)
Cell-cell and cell-environment interactions are controlled by a set of local rules that dictate cell behavior. With such local rules, emergence of computationally meaningful building blocks and hierarchies can be observed. For example, at the cellular level organization in the visual system, receptive field of a retinal ganglion cell displays an activation inhibition behavior that can be modeled as Mexican Hat wavelet or Difference of Gaussians. This precise organization is the product of a harmonious collaboration of different cell types located at the lower levels in a hierarchical structure for each ganglion cell. Moreover, a similar hierarchical organization is observed at higher levels in the visual system. This thesis investigates the visual system from several perspectives in an effort to explore the biological/computational principles underlying these local rules. The investigation results in a hybrid computer model that can combine the advantages of evolutionary and developmental principles to explore the effects of local rules on cellular differentiation, retinal mosaics, layered structures and network topology.
16

Microencapsulation Of Phenolic Compounds Extracted From Sour Cherry (prunus Cerasus L.) Pomace

Cilek, Betul 01 September 2012 (has links) (PDF)
The main objective of the study was to encapsulate the phenolic compounds from sour cherry pulp in micro size, to investigate the physicochemical properties of capsules and their digestability in simulated gastric and intestinal fluid. The effect of different coating materials, ultrasonication time and core to coating ratio on encapsulation of phenolic compounds from sour cherry pomace was investigated. Maltodextrin and gum Arabic were chosen as coating materials. Coating material was prepared with different maltodextrin:gum Arabic (MD:GA) ratios of 10:0, 8:2, 6:4 to make the total solid content 10%. In addition, two different core to coating ratios of 1:10 and 1:20 were used. Emulsions were prepared by homogenization through ultrasonication at 160 W power and 20 KHz frequency for different time periods (5-30 min). Then, the emulsions were freeze dried for 48 hours to obtain the microcapsules. Encapsulation efficiency, antioxidant activity, surface morphology, particle size, color, digestability and glass transition temperatures of the microcapsules were determined. The microcapsules with a core to coating ratio of 1:20 were found to have higher encapsulation efficiencies (78.80-92.26%) than those with a core to coating ratio of 1:10 (69.38-77.83%). Increasing the gum Arabic ratio in the coating material increased encapsulation efficiency. Optimum conditions for encapsulation with the highest efficiency and the lowest particle size were sonication time of 22.5 min, MD:GA ratio of 8:2 and core to coating ratio of 1:20. Encapsulation was effective in preventing the release of the phenolic compounds in gastric fluid. On the other hand, phenolic compounds were released from the capsules into the intestinal fluid.
17

Categorical Effect Studied Through Fmri In Color Perception

Koc, Seyma 01 October 2012 (has links) (PDF)
It is widely accepted that color is perceived categorically. Categorical perception of color can be defined as the tendency to discriminate colors that are from different categories easier, quicker and more accurately than colors that are from the same category. The present study investigated whether brain activity patterns verifies the concept of categorical color perception, an instantiation of top-down influences on low-level perception. Participants performed a color discrimination task on color pairs. Three categories of color pairs are defined in the green-blue region as follows. One of the pairs was specified as cross-category pair by choosing one color from green side of the green-blue boundary and the other color from blue side. The other two pairs were featured as within-category pairs by choosing two shades of green for within-green pair and two shades of blue for within-blue pair. Crucially, the pairs varied only in hue dimension and the physical distance between each of three pairs was set to 10 degrees in CIE LCh space. Pairs on the screen are displayed adjacently or with gaps in between, to further investigate the effect of space in color discrimination. Correct responses, reaction times and fMRI BOLD signals are recorded. Behavioral findings yielded a decrementing pattern from green to blue region challenging the prediction of categorical perception argument that performance is better at green-blue boundary than both within green and blue regions. Behavioral findings also indicated that adjacent display of colors facilitated color discrimination when compared to display of colors with spatial gaps. Brain activity patterns indicated that separate neural processes might underlie these distinct behavioral differences. Although standardized with respect to the color metric, the three categories of our experiment might have involved differences with respect to difficulty levels and memory requirements. Brain activity differences reported in the within-green condition versus cross-category condition are focused on Frontal Eye Fields and Fusiform Gyrus, which is seem to be modulated by Frontal Eye Field activity / increased activation in these regions is related to enhanced visual performance and higher scores, which is consistent with significantly better performance in within-green discrimination than cross-category discrimination. For the same contrast, Parahippocampal Gyrus and Precuneus activations suggest better visual recall and behavioral improvement due to more efficient maintenance in spatial working memory for within-green discrimination than cross-category discrimination. Brain activity differences reported in the within-blue condition versus cross-category condition is focused on Superior Temporal Gyrus, which is involved in color discrimination having the role of color memory. When within-green and within-blue conditions are compared, there was differential activation in the Fusiform Gyrus, and this is the only brain activity which might be attributed to a categorical effect. This comparison also yielded activity in Medial Frontal and Superior Frontal regions concerning more confident perceptual decisions and improved performance on within-green discrimination than within-blue discrimination. In addition, spatial separation of stimuli entailed more cognitive resources to color discrimination than adjacent stimuli as suggested by Cuneus and Lingual Gyrus activations. Overall, to the best of our knowledge our study is the first to investigate the neural framework for color perception, which revealed that color perception might involve several complex sub-processes that activate memory and attention.
18

Software Functionalitymodel For Functional Size Measurement

Ozkan, Baris 01 September 2012 (has links) (PDF)
Functional size is among the few software size measures for which well-structured and standardized methods exists for its measurement. Although Functional Size Measurement(FSM) methods have gone a long way, one ongoing criticism on FSM methods is the discrepancies in the measurement results of the same software obtained by different measures. In this thesis study the sources of discrepancies that involve the functional properties of measurands and constructs of the FSM method models are investigated in two exploratory case studies. In the light of the findings, a software functionality model for functional size measurement is proposed. The model is founded on a characterization of software functionality from a requirements engineering point of view and it aims is to facilitate reliable size measurements on the basis of formalized concepts and rules. Two case studies are conducted in order to evaluate the applicability of the model and validate its effectiveness.
19

Analysis Of An Options Contract In A Dual Sourcing Supply Chain Under Disruption Risk

Kole, Huseyin 01 September 2012 (has links) (PDF)
In this study, value of demand information and the importance of option contracts are investigated for a supply chain consisting of a buyer and two suppliers in a single period setting. One supplier is cheap but prone to disruptions whereas the other one is perfectly reliable but expensive. At the beginning of the period, buyer orders from the unreliable supplier and reserves from the reliable supplier through a contract that gives buyer an option to use reserved units after getting disruption information of first supplier. We introduce three models which differ in terms of the level of information available when the ordering decisions are made. In the full information model, the options are exercised after getting disruption and demand information / in the partial information model, the options are exercised after getting disruption information before demand information. In the no information model, there is no options contract and units are ordered from the reliable supplier when buyer has no information about demand and disruption. Through the analysis of these models, we explore the value of advance demand and disruption information in the presence of an options contract.
20

Prediction Of Non-darcy Flow Effects On Fluid Flow Through Porous Media Based On Field Data

Alp, Ersen - 01 October 2012 (has links) (PDF)
The objective of this dissertation is to investigate the non-Darcy flow effects on field base data by considering gas viscosity, gas deviation factor and gas density as variables. To achieve it, different correlations from the literature and field data have been combined to Sawyer-Brown Method, thus a contribution has been achieved. Production history of selected gas field has been implemented to a numerical simulator. To find out non-Darcy effects quantitatively, Darcy flow conditions have also been run in the simulator for each scenario in addition to non-Darcy flow correlation runs. Extracted data from simulation runs have been analyzed on the basis of Sawyer-Brown Method by introducing several correlations to consider gas viscosity, gas deviation factor and gas density as variables. Engineering and scientific research on non-Darcy flow is still being conducted in order for better understanding the nonlinear flow behavior of fluids through porous media. The deviations from Darcy&rsquo / s Law are attributed to the occurrence of all or alternating combinations of factors that can be categorized as the anisotropy of porosity and permeability, multi-phase flow of fluids in varying phases, magnitude of pressure drop and the subsequent phase change in fluids, and the change in flow regime at elevated rates of flow in porous media. Throughout this dissertation, the factors causing deviations from Darcy flow behavior have been investigated.

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