This dissertation focuses on the challenge of soil hydraulic parameter scaling in soil hydrology and related applications in general; and, in particular, the upscaling of these parameters to provide effective values at coarse scales. Soil hydraulic properties are required for many hydrological and ecological models at their representative scales. Prediction accuracy of these models is highly dependent on the quality of the model input parameters. However, measurement of parameter data at all such required scales is impractical as that would entail huge outlays of finance, time and effort. Hence, alternate methods of estimating the soil hydraulic parameters at the scales of interest are necessary. Two approaches to bridge this gap between the measurement and application scales for soil hydraulic parameters are presented in this dissertation. The first one is a stochastic approach, based on artificial neural networks (ANNs) applied within a Bayesian framework. ANNs have been used before to derive soil hydraulic parameters from other more easily measured soil properties at matching scales. Here, ANNs were applied with different training and simulation scales. This concept was further extended to work within a Bayesian framework in order to provide estimates of uncertainty in such parameter estimations. Use of ancillary information such as elevation and vegetation data, in addition to the soil physical properties, were also tested. These multiscale pedotransfer function methods were successfully tested with numerical and field studies at different locations and scales. Most upscaling efforts thus far ignore the effect of the topography on the upscaled soil hydraulic parameter values. While this flat-terrain assumption is acceptable at coarse scales of a few hundred meters, at kilometer scales and beyond, the influence of the physical features cannot be ignored. anew upscaling scheme which accounts for variations in topography within a domain was developed to upscale soil hydraulic parameters to hill-slope (kilometer) scales. The algorithm was tested on different synthetically generated topographic configurations with good results. Extending the methodology to field conditions with greater complexities also produced good results. A comparison of different recently developed scaling schemes showed that at hill-slope scales, inclusion of topographic information produced better estimates of effective soil hydraulic parameters at that scale.

Hydraulic fracturing is a popular stimulation method in tight gas and shale gas reservoirs that uses a viscous fluid to fracture the reservoir rock and uniformly transport proppant to create a highly conductive path that is kept open by the proppant after fracturing. This method is used to improve the productivity of the otherwise low permeability reservoirs. Hydraulic fracturing, though in general beneficial, is a complex process that has a number of challenges in fracturing design and execution. This research focuses on studying the damage caused by the fracturing fluid (gel) to the fracture and the conditions to remove the damage. Guar gum and its derivatives have been the most commonly used polymers to increase the viscosity of fracturing fluids. The fracturing fluid gets dehydrated under pressure leaving behind a highly concentrated unbroken residue called filter cake which causes permeability impairment in the proppant pack, resulting in low fracture conductivity and decreased effective fracture length. This study seeks to characterize filter cakes. By measuring its thickness and with the leak off volume, the concentration and yield stress of the filter cake can be estimated. The thickness of the filter cake was measured with a precise laser profilometer. Correlations are proposed to estimate filter cake properties (thickness, concentration and yield stress) based on pumping conditions (pump rate, time and net pressure) and rock properties. With these properties known, a required flow back rate of the reservoir fluid can be estimated to clean up the filter cake modeled as a non-newtonian fluid exhibiting a yield stress. Typical field conditions were referenced and scaled down in the lab to closely represent the field conditions. Recommendations are provided on gel damage based on the observation of the study.

This study aims to develop a computer program to optimize the performance of loader mechanisms in backhoe-loaders. The complexity and the constraints imposed on the loader mechanism does not permit the use of classical optimization techniques used in the synthesis of mechanisms. Genetic algorithm is used to determine the values of the design parameters of the mechanism while satisfying the constraints and trying to maximize breakout forces that the machine can generate.

Borders of flow field around immersed bodies can be extended to long distances since there are no physical boundaries. In computational practice however, the flow domain must be restricted to a reasonable size by imposing appropriate boundary conditions at the edges of the computational space. In this thesis work, streamlines obtained from potential flow solution in a relatively large spatial domain are utilized to specify the boundaries and boundary conditions for a more restricted computational domain to be used for detailed viscous flow computations. A grid generation code is adopted for generation of unstructured triangular grid systems for domains involving multiple immersed bodies of any shape at arbitrary orientations such as a group of tall buildings in horizontal plane. Finite volume method is used in the solution of Laplace equation for the stream function. A deformation modulus is introduced as a probe parameter to aid locating the viscous flow boundaries. The computer code acts as a preprocessor for viscous flow computations, specifying the computational boundaries, the boundary conditions and generating the computational grid.

The design and development of isolation or backfill materials, which seal the disposal facility, are important for disposing the wastes. The use of compacted bentonite-sand for construction of shaft seals and liners for waste containment structures has been proposed by various studies. Therefore / it is aimed in this study to develop an isolation material to be used in underground waste repositories. For such designs to be effective, their performance need to be assessed and a minimum hydraulic conductivity requirement defined by regulatory agencies should be satisfied (i.e. 1x10-8 m/s in Turkey, 1x10-9 m/s in USA). Therefore / this study assesses the performance of compacted bentonite/sand mixtures in terms of hydrological and mechanical properties. To be able to assess the performance of this material, a variety of laboratory tests were carried out. Engineering geological tests such as compaction, falling head permeability, swelling, unconfined compression and shear strength tests were conducted to select an optimum mixture. Finally, an optimum bentonite-sand mixture possessing 30% bentonite was recommended for the isolation of underground waste disposal facilities.

ABSTRACT DESIGN OF A DEMOLITION BOOM &Ccedil / etin, Bet&uuml / l M.S, Department of Mechanical Engineering Supervisor : Prof. Dr. Eres S&Ouml / YLEMEZ August 2007, 96 pages Excavators are used for many purposes. Some of these are digging, drilling, breaking and demolition. A demolition excavator boom consists of 3-piece boom which is different in form and construction from a 2-piece boom used in standard excavator. The aim of this thesis is to design a demolition boom for hydraulic excavator with operation weight of 30 ton. With this construction a higher reach is gained. Design of the demolition boom consists of three stages. Firstly the mechanism design is performed to determine the basic link dimensions. In the second step the structural shape of the boom is estimated to perform static stress analysis. The EXCEL program is chosen due to the ease of repetative calculations and applying the changes in structure parameters. The demolition boom is modeled by PRO-ENGINEER, and consequently the model is analyzed by using a Finite Element Analysis (FEA) in MSC.Marc-Mentat. According to the FEA results the model is revised. Keywords: Demolition Excavator, Mechanism Design, Structural design

Previous studies have shown that screens may be utilized efficiently for dissipating the energy of water. For the present study, a series of experimental works are executed to investigate the tailwater and multiple screen effects on the energy dissipation through screens. Water flowing beneath a sliding gate is used to simulate the flow downstream of a hydraulic structure. In the present study, one double screen and two double screen arrangements with porosity of 40% and inclination angle of 90 degree is used. A tailwater gate structure is used to adjust the tailwater depth. The major parameters for the present study are upstream flow depth, tailwater gate height, location of the screen together with the supercritical upstream flow Froude number for a range covering from 5.0 to 22.5. The gate opening simulating a hydraulic structure is adjusted at heights of 2 cm and 3 cm during the study. The results of the experiments show that the tailwater depth has no significant additional contribution on the energy dissipation, whereas multiple screen arrangement dissipates more energy as compared to one double screen arrangement.

In the present thesis the performance of box type floating breakwaters (FBs) with screens under regular waves is examined experimentally in a wave flume. The experiments were conducted in the Coastal and Harbor Engineering Laboratory wave flume, Civil Engineering Department, Middle East Technical University, Ankara. The influence of incident wave characteristics and certain geometric characteristics, such as the width and draft of the structure, on its effciency is examined. Three different widths of the structure in combination with three different screen (draft) height, a total of nine different cases, of FBs are examined. Results related to transmission and reflection of the incident regular waves on the structure are presented. According to the results, for all structures drafts and structure widths, as h/L increase (wave period and wave height decreases) Kt values decrease. Also, Kt values obtained for chain moored floating breakwaters are larger than the Kt values of fixed cases consistently.

An impermeable weir constructed across a stream prevents the longitudinal movement of aquatic life and transportation of physical and chemical substances in water, eventually having a negative impact on river environment. However, a rubble mound weir is considered environmentally friendly, since its permeability allows the streamwise migration of aquatic life. This thesis investigates the performance of this type of weir as a water use facility. The particular objective of the investigation is to study the flow mechanism in terms of water surface profile and discharge through the weir. In the study, flow through the rubble mound weir is considered non-Darcian, steady, and one-dimensional. In the analysis, gradually varied open channel flow algorithm is applied to porous medium flow through the rubble mound weir in which laminar and turbulent components of flow are taken into consideration. Unlike previous studies where Stephenson and Wilkins relations were used, in this thesis Forchheimer equation is used. To verify the validity of numerical solution of governing equation based on Forchheimer relation, an experimental investigation is conducted in the laboratory. The experimentally obtained water surface profiles are compared with the numerical results. It is observed that there is a satisfactory agreement between numerical and experimental results. The water surface profiles obtained by numerical solution are further compared with those based on Stephenson and Wilkins relations. It is concluded that the proposed numerical solution technique for the Forchheimer based governing equation may be used in the analysis of flow through, and design of rockfill weirs.

The performance of outlets under constant head is investigated in this study. Behavior of single outlet is analyzed / subsequently effect of multiple outlets on a single outlet is examined. Parameters taken into account are constant head of water, orifice shape, orifice length, number of open outlets and discharge. The outlet type, which is examined, can be classified as a short tube orifice. Two different orifice diameters and tube lengths are used. Outlets had the diameter, 6.00 and 10.35mm. The ratio of orifice length to diameter (l/d) was 5 and 8. Number of outlets is 5, which are opened in several combinations. A dimensional analysis shows that discharge coefficient, Cd is a function of diameter-length ratio and the Reynolds Number. In this study, high Reynolds Number (2300&lt / Re&lt / 18600) range is examined and the results are compared with the available data in the literature. Furthermore, performance of the group outlets is investigated.