In this study, the limitations of point-source stochastic simulations are investigated in terms of fundamental geophysical parameters. Within this context, a total of 6000 synthetic ground motions are generated for various magnitude (5.0 &amp / #8804 / Mw &amp / #8804 / 7.5), source-to-site distance (less than 100 km), faulting style (shallow dipping and strike-slip) and site class (soft, stiff and rock) bins. The simulations are performed in two main stages: (1) the acceleration time series at outcropping very hard rock sites are simulated based on the stochastic method proposed by Boore (1983, 2003) and (2) they are modified through 1-D equivalent linear site response analysis to generate the free-field motions at soft, stiff and rock sites. Thus, as a part of this study, a probability-based soil profile model that considers the random variation of S-wave slowness as a function of depth is derived. The synthetic ground motions are assessed with several recent empirical ground-motion models to constitute the limitations of the simulation procedure. It is believed that the outcomes of this study will realistically describe the limitations of stochastic point-source simulation approach that can be employed further for the studies on improvements of this simulation technique.

In some classification problems where human judgments, qualitative and imprecise data exist, uncertainty comes from fuzziness rather than randomness. Limited number of fuzzy classification approaches is available for use for these classification problems to capture the effect of fuzzy uncertainty imbedded in data. The scope of this study mainly comprises two parts: new fuzzy classification approaches based on Tanaka&rsquo / s Fuzzy Linear Regression (FLR) approach, and an improvement of an existing one, Improved Fuzzy Classifier Functions (IFCF). Tanaka&rsquo / s FLR approach is a well known fuzzy regression technique used for the prediction problems including fuzzy type of uncertainty. In the first part of the study, three alternative approaches are presented, which utilize the FLR approach for a particular customer satisfaction classification problem. A comparison of their performances and their applicability in other cases are discussed. In the second part of the study, the improved IFCF method, Nonparametric Improved Fuzzy Classifier Functions (NIFCF), is presented, which proposes to use a nonparametric method, Multivariate Adaptive Regression Splines (MARS), in clustering phase of the IFCF method. NIFCF method is applied on three data sets, and compared with Fuzzy Classifier Function (FCF) and Logistic Regression (LR) methods.

In the last three decades, seismic performance assessment of buried structures has evolved through the following stages : i) buried structures are not prone to seismically-induced damages, thus no need for detailed investigations, ii) eliminating soil-structure-earthquake interaction and use of seismically-induced free field ground deformations directly as the basis for seismic demand, thus producing conservative results, and finally iii) soil-structure and earthquake interaction models incorporating both kinematic and inertial interactions. As part of soil-structure and earthquake interacting models, simplified frame analysis established the state of practice and is widely used. Within the confines of this thesis, the results of simplified frame analysis based response of buried structures are compared with those of 2-D finite element dynamic analyses. For the purpose, 1-D dynamic and 2-D pseudo-dynamic analyses of free field and buried structural systems are performed for a number of generic soil, structure and earthquake combinations. The analyses results revealed that, in general, available closed form solutions are in pretty good agreement with the results of finite element analyses. However, due to the fact that dynamic analyses can model both kinematic and inertial effects / it should be preffered for the design of critical structures.

This study aims to investigate hydraulics and the flow characteristics of drilling fluids inside annulus and to understand the mechanism of cuttings transport in horizontal and deviated wellbores. For this purpose, initially, extensive experimental studies have been conducted at Middle East Technical University, Petroleum &amp / Natural Gas Engineering Flow Loop using water and numerous drilling fluids for hole inclinations from horizontal to 60 degrees, flow velocities from 0.64 m/s to 3.05 m/s, rate of penetrations from 0.00127 to 0.0038 m/s, and pipe rotations from 0 to 120 rpm. Pressure loss within the test section and stationary and/or moving bed thickness are recorded. New friction factor charts and correlations as a function of Reynolds number and cuttings bed thickness with the presence of pipe rotation for water and drilling fluids in horizontal and deviated wellbores are developed by using experimental data. Meanwhile empirical correlations that can be used easily at the field are proposed for predicting stationary bed thickness and frictional pressure loss using dimensional analysis and the effect of the drilling parameters on hole cleaning is discussed. It has been observed that, the major variable influencing cuttings transport is fluid velocity. Moreover, pipe rotation drastically decreases the critical fluid velocity that is required to prevent the stationary cuttings bed development, especially if the pipe is making an orbital motion. A decrease in the pressure loss is observed due to the bed erosion while rotating the pipe. Cuttings transport in horizontal annulus is modeled using a CFD software for different fluid velocities, pipe rotation speeds and rate of penetrations. The CFD model is verified by using cuttings transport experiments. A mathematical model is also proposed to predict the flow characteristics of Newtonian fluids in concentric horizontal annulus with drillpipe rotation. The Navier-Stokes equations of turbulent flow are numerically solved using finite differences technique. A computer code is developed in Matlab 2007b for the proposed model. The performance of the proposed model is compared with the experimental data which were available in the literature and gathered at METU-PETE Flow Loop as well as Computational Fluids Dynamics (CFD) software. The results showed that the mechanistic model accurately predicts the frictional pressure loss and the velocity profile inside the annuli. The model&rsquo / s frictional pressure loss estimations are within an error range of &plusmn / 10%.

In Multi-Skill Project Scheduling Problem (MSPSP) with hierarchical levels of skills, there are more than one skill type and for each skill type there are levels corresponding to proficiencies in that skill. The purpose of the problem is to minimize or maximize an objective by assigning resources with different kinds of skills and skill levels to the project activities according to the activity requirements while satisfying the other problem dependent constraints. Although single-objective case of the problem has been studied by a few researchers, biobjective case has not been studied yet. In this study, two objectives, which are the makespan and the total skill wasted, are taken into account and while trying to minimize the makespan, minimizing the total skills wasted is aimed. By the second objective, overqualification for the jobs is tried to be minimized in order to prevent job dissatisfaction. The biobjective problem is solved using a Multiobjective Genetic Algorithm, NSGA-II. The results of the proposed algorithm are compared with the GAMS results for small-sized problems and with the random search for larger problem sizes.

This thesis investigates methane emissions and methane production potentials from abandoned longwall panels produced or emitted due to mining activities either from coal seam or any underlying or overlying formations. These emissions can increase greenhouse gas concentrations and also pose a danger to the underground working environment and to miners. In addition to the safety issues, recovery and utilization of this gas is an additional source of energy. In this study, methane concentrations measured from ventilation air ways in Yeni &Ccedil / eltek Coal Mine, which is located in Suluova basin, Amasya, and contains thick, laterally extensive Lower Eocene coal seams, were integrated within a numerical vi reservoir model. Key reservoir parameters for history matching are cleat permeabilities, cleat porosity, diffusion time and Langmuir volume and Langmuir pressure. Thirteen cases were studied. According to the results, Case-10 determined as the best fitted case for both of the production wells. Cleat permeabilities and Langmuir pressure were the most effective parameters. Reservoir parameters matched are cleat permeabilities of 5, 4 and 1 md and fracture dimensions of 0.8, 0.4, and 0.1 m in x, y and z direction respectively, 2 % cleat porosity, 0.3 % water saturation. Diffusion time was determined as 400 days and 2000 kPa Langmuir volume and 6.24279 m3 /tone gas content estimated. According to these results it can be said that methane production will not be economically feasible, however / to remedy underground working conditions and safety of workers methane management should be taken into consideration.

The purpose of this study was to develop and evaluate engineering self-efficacy measures for undergraduate students (N = 321) and to examine whether students' engineering self-efficacy differed by gender, year level, and major. The relationships between engineering self-efficacy and academic achievement and intent to persist in engineering were also investigated. Data from engineering students from two southeastern universities were collected in spring 2013. Exploratory factor analyses resulted in a unidimensional general engineering self-efficacy scale and a three-factor (i.e., research skills, tinkering skills, and engineering design) engineering skills self-efficacy scale. Multivariate analyses of variance revealed that self-efficacy did not differ by gender or year level. Students in different engineering sub disciplines reported different levels of tinkering self-efficacy. Multiple regression analysis showed that engineering self-efficacy measures predicted academic achievement outcomes but not intent to persist in engineering. Engineering self-efficacy significantly contributed to the prediction of achievement after controlling for prior achievement. Research funded by the National Science Foundation, EEC Award No.1240328.

Expansive or swelling soils, exist in many part of the world, show excessive volume changes with increasing water content. As a result of this volume increase, expansive soils apply vertical and lateral pressures to the structures located or buried in these regions. Many researchs have been carried out on vertical swelling pressures helping to the engineers to design structures withstanding on these stresses. However, lateral swell behaviour of swelling soils have not been fully understood yet. Structures such as / basement walls, water tanks, canals, tunnels, underground conduits and swimming pools which will be built in expansive soils have to be designed to overcome the lateral swelling pressures as well as the other lateral pressures exerted by the soil. For this aim accurate and reliable methods are needed to predict the magnitude of lateral swelling pressures of expansive soils and to understand the lateral swelling behaviour of expansive soils. In this experimental study, the lateral swelling behaviour of an highly expansive clay is investigated using a modified thin wall oedometer which was developed in the METU Civil Engineering Department Soil Mechanics Laboratory earlier. Statically compacted samples were used in constant volume swell (CVS) tests to measure the magnitude of the lateral and vertical swelling pressures. To study the relationship between the lateral and vertical sweeling pressures, they were measured simultaneously. The samples having different initial water contents and different initial dry densities were used to study the effects of these variables on the vertical and the lateral swelling pressures. It is observed that both lateral and vertical pressures increases with increasing initial dry density and they decrease with increasing initial water content. Swell pressure ratio, the ratio of lateral swelling pressure to the vertical one, is increasing with increasing initial water content. Time needed to obtain the magnitude of maximum lateral and vertical pressures decreases with increasing initial water content and increases with increasing initial dry density.

Dams are large hydraulic structures constructed to meet various project demands. Their roles in both environment and the economy of a country are so important that their design and construction should be carried out for negligibly small risk. Conventional design approaches are deterministic, which ignore variations of the governing variables. To offset this limitation, high safety factors are considered that increase the cost of the structure. Reliability&ndash / based design approaches are probabilistic in nature since possible sources of uncertainties associated with the variables are identified using statistical information, which are incorporated into the reliability models. Risk analysis with the integration of risk management and risk assessment is a growing trend in dam safety. A computer program, named CADAM, which is based on probabilistic treatment of random loading and resistance terms using Monte&ndash / Carlo simulation technique, can be used for the safety analysis of gravity dams. A case study is conducted to illustrate the use of this program.

A model study on laterally braced sheet pile walls retaining cohesionless soil was conducted using 1-g shaking table. Lateral dynamic earth pressures, backfill accelerations and dynamic displacement of walls were measured. Input accelerations were kept between 0.03g to 0.27g. A data acquisition system consisting of dynamic pressure transducers, accelerometers, displacement transducer, signal conditioning board and a data acquisition card compatible with a personal computer was used during the study. Three different walls with thicknesses of 6.6, 3.2 and 2.0 mm were used in order to investigate the effects of changing wall stiffness value on lateral seismic pressures developed on the wall. In addition to that, steel blocks were placed on top of the backfill in order to simulate a surcharge effect of 1.57 kPa to 3.14 kPa during shaking. Amplification of input acceleration, incremental seismic lateral thrusts and corresponding maximum dynamic pressures, application point of the resultant, effect of stiffness and surcharge on maximum seismic lateral thrust and dynamic wall deflections were calculated by processing raw data stored. The results were compared to previous model studies and some analytical methods available.