The North Anatolian Fault (NAF) is one of the world&rsquo / s largest active continental strikeslip faults, and forms the northern margin of the Anatolian plate. Although its geologic and geomorphologic features are well defined, crustal deformation and associated seismicity around central segment of the NAF is relatively less-known. In this study, we analyzed locations and focal mechanisms of 172 events with magnitude &ge / 3, which are recorded by 39 broadband seismic stations deployed by the North Anatolian Passive Seismic Experiment (2005-2008). Distribution of the events shows that the local seismicity in the area is widely distributed, suggesting a widespread continental deformation, particularly in the southern block. For the entire data set, P- and S- arrival times are picked and events are relocated using the HYPOCENTER program. Then, relocated events which have a good azimuthal coverage with a maximum gap of 120&deg / and at least 13 P- wave readings are selected and 1-D inversion algorithm, VELEST, is used to derive the 1-D seismic velocity model of the region. The final model with updated locations is later put together to the FOCMEC program, to obtain focal mechanisms solutions. In this step, an iterative scheme is applied by increasing the number of data errors. To obtain more unique solutions, first motions of P and SH v phases are used along with SH/P amplitude ratios. Resultant 109 well-constrained focal mechanisms later used to perform stress tensor inversion across the region. Our focal mechanisms suggest a dominant strike-slip deformation along two major fault sets in the region. In the east, E-W trending splays (Ezinepazari, Almus, and La&ccedil / in Kizilirmak) show right-lateral strike-slip motion similar to the NAF whereas in the west, N-S trending faults (Dodurga, Eldivan) show left lateral strike-slip motion. Overall, stress orientations are found as: maximum principal stress, &sigma / 1, is found to be subhorizontal striking NW-SE, the intermediate principle stress, &sigma / 2, is vertically orientated and the minimum principal stress, &sigma / 3, is found to be NE &ndash / SW striking, consistent with the strike-slip regime of the region.

Heat transfer of two-dimensional, hydrodynamically developed, thermally developing, single phase, laminar flow inside a microtube is studied analytically with constant wall temperature thermal boundary condition. The flow is assumed to be incompressible and thermo-physical properties of the fluid are assumed to be constant. Viscous dissipation and the axial conduction are included in the analysis. Rarefaction effect is imposed to the problem via velocity slip and temperature jump boundary conditions for the slip flow regime. The temperature distribution is determined by solving the energy equation together with the fully developed velocity profile. Analytical solutions are obtained for the temperature distribution and local and fully developed Nusselt number in terms of dimensionless parameters / Peclet number, Knudsen number, Brinkman number, and the parameter &amp / #954 / . The results are verified with the well-known ones from literature.

In this study, effect of surface roughness on convective heat transfer and fluid flow in two dimensional parallel plate microchannels is analyzed by numerically. For this purpose, single-phase, developing, laminar fluid flow at steady state and in the slip flow regime is considered. The continuity, momentum, and energy equations for Newtonian fluids are solved numerically for constant wall temperature boundary condition. Slip velocity and temperature jump at wall boundaries are imposed to observe the rarefaction effect. Effect of axial conduction inside the fluid and viscous dissipation also considered separately. Roughness elements on the surfaces are simulated by triangular geometrical obstructions. Then, the effect of these roughness elements on the velocity field and Nusselt number are compared to the results obtained from the analyses of flows in microchannels with smooth surfaces. It is found that increasing surface roughness reduces the heat transfer at continuum conditions. However in slip flow regime, increase in Nusselt number with increasing roughness height is observed. Moreover, this increase is found to be more obvious at low rarefied flows. It is also found that presence of axial conduction and viscous dissipation has increasing effect on heat transfer in smooth and rough channels.

In this study simultaneously developing single phase, laminar and incompressible flow in a micro gap between parallel plates is numerically analyzed by including the effect of variation in thermal conductivity and viscosity with temperature. Variable property solutions for continuity, momentum and energy equations are performed in a coupled manner, for air as a Newtonian fluid. In these analyses the rarefaction effect, which is important for the slip flow regime, is taken into account by imposing slip velocity and temperature jump boundary conditions to the wall boundaries. Mainly, the influence of viscous dissipation, axial conduction, geometric parameters and rarefaction on the property variation effect is aimed to be discussed in detail. Therefore, the effects of variable thermal conductivity and viscosity are investigated simultaneously with the effects of rarefaction, geometric parameters, viscous dissipation and axial conduction. The difference between constant and variable solutions in terms of heat transfer characteristics is related to the effects of viscous dissipation axial conduction and rarefaction. According to results, property variation is substantially effective in the entrance region where temperature and velocity gradients are high. On the other hand, property variation effects are not significant for fully developed air flows in microchannel.

In order to understand the tectonic evolution of the Kalecik region (Ankara, Turkey), a structural field study was performed in a selected area located in the east of Kalecik, where mostly imbricated thrust sheets of the Cretaceous Ophiolitic melange crop out. In the study area, the Cretaceous Ophiolitic melange, Cretaceous radiolaria-bearing sequences and the Paleocene units are all intruded by sub-vertical dykes. The attitudes of planar structures (dykes, beds and faults) and the kinematic data measured on faults were analyzed by using &ldquo / ROCKWORKS 2002&rdquo / and &ldquo / Angelier Direct Inversion Method (version 5.42)&rdquo / softwares, respectively. A major trend of NE-SW (045&deg / N) direction and relatively a post-Paleocene &ndash / pre-Miocene age was determined for the dykes indicating an extension in the NW-SE direction during post-Paleocene. The dykes cut bedded units displaying a dominant set trending in WNW-ESE (297&deg / N) direction and mostly dipping towards NE with moderate dip amounts. But at the same time, the Upper Cretaceous units were observed as intensely folded, faulted and thrusted due to the compressional regime that acted in Central Anatolia during Late Cretaceous. The angular difference between the major trend of dykes and the dominant trend of stratification was found as approximately 108&deg / ., which may also indicate that the dykes and beds were evolved during different deformation periods. The results of the kinematic analyses of different age faults revealed that the post-Paleocene &ndash / pre-Miocene Kalecik basaltic dykes are deformed under a continuous NW-SE-oriented post-Paleocene compressional to strike-slip tectonic regime which was followed by a NNW-SSE oriented post-Miocene extensional-transtensional regime.

RHex is an autonomous hexapedal robot capable of locomotion on rough terrain. Up to now, most modelling and simulation efforts on RHex were based on the linear leg assumption. These models disregarded what might be seen as the most characteristic feature of the latest iterations of this robot: the half circular legs. This thesis focuses on developing a more realistic model for this specially shaped compliant leg and studying its effects on the kinematics and dynamics of the resulting platform. One important consequence of the half circular compliant leg is the resulting rolling motion. Due to rolling, the rest length of the leg changes and the leg-ground contact point moves. Another consequence is the varying stiffness of the legs due to the changing rest length. These effect the resulting behaviour of any platform using these legs. In the first part of the thesis we are studying the effects of the half circular leg morphology on the kinematics of RHex using a simple planar model. The rest of the studies within the scope of this thesis focuses on the effect of the half circular compliant legs on the dynamics of a single legged hopping platform with a point mass. The formulation derived in this work is successfully integrated in a readily working but rather simple model of a single legged hopping system. We replace the equations of the straight leg in this model by the equations of the half circular compliant leg. Realistic results are obtained in the simulations and these results are compared to those obtained by the simpler constant stiffness straight leg model. This more realistic leg model brings us the opportunity to further study the effects of this leg morphology, in particular the positive effects of the resulting rolling motion on platform stability.

An understanding of the damage evolution prior to crack initiation in advanced structural materials is of vital importance to the fatigue community in both academia and industry. Features known as the Persistent Slip Bands (PSBs) play an integral role in this damage evolution. Therefore, PSBs have been the focus of a lot of science-based investigations over the years. However, most existing studies in this area are restricted to analysis of PSBs in single crystal face centered cubic (FCC) materials. Moreover, these studies lack a quantitative analysis of the evolution of the fatigue damage (or PSBs) as a function of the material microstructure. This is especially true for relatively modern materials such as the Advanced High Strength Structural (AHSS) steels that are gaining a lot of importance in the automotive sector. Accordingly, the objective of this research is to quantitatively characterize evolution of PSBs in three AHSS steels having different microstructures as a function of number of fatigue cycles and strain amplitude. For this purpose strain controlled interrupted fatigue tests have been performed on two dual phase steels (DP-590 and DP-980) having different relative amounts of tempered martensite and a ferritic high strength low alloy steel (HR-590). Digital image analysis and Stereology have been used for unbiased quantitative characterization of the evolution of global geometry of the PSB colonies as function of number of fatigue cycles and strain amplitude. Evolution of PSB colonies has been couched in terms of variation of PSB colony volume fraction and total surface area unit volume, and total surface area of individual PSBs per unit volume and three-dimensional angular orientation distribution of the PSBs. For this purpose, new stereological techniques have been developed for estimation of the three-dimensional angular orientation distribution. The stereological data reveal that during strain controlled in these AHSS steels, volume fraction of the PSB colonies varies linearly with the their total surface area per unit volume. Detailed analysis of the stereological data leads to a simple geometric model for evolution of the PSB colonies in the three AHSS steels, which accounts for all observed data trends.

Buckle arrestors are devices placed along an offshore pipeline for the purpose of arresting an incoming propagating buckle. Typically, buckle arrestors locally increase the pipe’s bending rigidity in the hoop direction. Spiral buckle arrestors are rods closely wound around the pipe for a number of turns and then welded at the ends to secure it in place. Spiral buckle arrestor have some key advantages to other designs in that they provide limited resistance to axial bending of the pipeline, and they can be wound on a continuous line away from free ends. This thesis uses a combination of experiments and modeling to study the effectiveness of spiral buckle arrestors. A series of experiments are conducted using 1.25-inch diameter SS-304 tubes with diameter-to-thickness ratios of 19 and 25. Stainless steel rods of four diameters are wound on tubes for a chosen number of turns and secured in place. A propagating buckle is subsequently initiated in the tube, engages the arrestor quasi-statically, is temporarily arrested, and eventually crosses the arrestor at a pressure defined as the crossover pressure. The crossover pressure was found to depend on the tube D/t and mechanical properties; and the rod diameter, number of turns, and mechanical properties. Finite element models are developed that enable the simulation of rod winding, buckle propagation, and buckle crossover. Local collapse is induced by external pressure and is propagated quasi-statically until it engages the arrestor. The pressure is increased until the buckle crosses the arrestor. The model is shown to reproduce the experimental observations and a large number of the measured crossover pressures with sufficient accuracy. Additional simulations were performed varying the rod diameter, numbers of turns, and tube D/t in order to enrich the database developed. This database was subsequently used to develop an empirical design formula for the arresting efficiency based on key nondimensional parameters of the problem. As was the case for the slip-on buckle arrestor, the arresting efficiency is bounded by the confined propagation pressure of the pipe. / text

The northwest part of the North America-Caribbean plate boundary zone is characterized by active, left-lateral strike-slip faults that are well constrained seismically and are corroborated by on- and offshore geologic mapping. The onshore plate boundary zone comprises the Motogua and Polochic fault systems of southern Guatemala which join and continue offshore as the Swan Islands fault zone along the southern edge of the Cayman trough. At the Mid-Cayman spreading center in the central Caribbean Sea, the fault motion is transferred at a 100 km wide left-step in the fault system to the Oriente fault zone. A third system, the Walton fault zone, continues east from the Mid-Cayman Spreading center to define the Gonave microplate. Seafloor features produced by strike-slip faulting along the Swan Islands and Walton fault zones have been imaged and mapped using the SeaMARC II side-scan sonar and swath bathymetric mapping system, single-channel seismic data, multichannel seismic data and 3.5 kHz depth profiles. Structures mapped along the Swan Islands and Walton fault zones include: 1) twenty-six restraining bends and five releasing bends ranging in size from several kilometers in area to several hundred kilometers in area; 2)en echelon folds which occur only within the restraining bends; 3) straight, continuous fault segments of up to several tens of kilometers in length; 4) restraining and releasing bends forming in "paired" configurations; and 5) a fault-parallel fold belt fold and thrust belt adjacent to a major restraining bend. The features observed along the Swan Islands and Walton fault systems are compared to other features observed along other strike-slip fault systems, from which empirical models have previously been derived. Based on the features observed in these strike-slip systems, a rigid plate scenario is envisioned where the geometry of the fault and the direction of plate motion have controlled the types of deformation that have occurred. In a related study, microtectonic features in an area of Neogene extension within the northwestern Caribbean plate were investigated in order to provide insight on the nature of intraplate deformation related to the motion along the plate boundary. Microtectonic features were measured in the Sula-Yojoa rift of northwestern Honduras with the intention of inverting the data to estimate stress states responsible for the observed strains. Data inversion for the estimation of stress states could not be undertaken with the available measurements, however, the observations made can be used to support several existing models for the intraplate deformation as well as to encourage the elimination of other models. / text

Traction efficiency of tractors barely reaches 50 % in field operations. On the other hand, modern trends in agriculture show growth of the global tractor markets and at the same time increased demands for greenhouse gas emission reduction as well as energy efficiency due to increasing fuel costs. Engine power of farm tractors is growing at 1.8 kW per year reaching today about 500 kW for the highest traction class machines. The problem of effective use of energy has become crucial. Existing slip control approaches for tractors do not fulfil this requirement due to fixed reference set-point. The present work suggests an optimal control scheme based on set-point optimization and on assessment of soil conditions, namely, wheel-ground parameter identification using fuzzy-logic-assisted adaptive unscented Kalman filter.