The simulation of seafloor-steel catenary interaction and prediction of riser fatigue life required an accurate characterization of seafloor stiffness as well as realistic description of riser load-deflection (P-y) response. This thesis presents two load-deflection (P-y) models (non-degradating and degradating models) to simulate seafloor-riser interaction. These two models considered the seafloor-riser system in terms of an elastic steel pipe supported on non-linear soil springs with vertical motions. These two models were formulated in terms of a backbone curve describing self-embedment of the riser, bounding curves describing P-y behavior under extremely large deflections, and a series of rules for describing P-y behavior within the bounding loop. The non-degradating P-y model was capable of simulating the riser behavior under very complex loading conditions, including unloading (uplift) and re-loading (downwards) cycles under conditions of partial and full separation of soils and riser. In the non-degradating model, there was a series of model parameters which included three riser properties, two trench geometry parameters and one trench roughness parameter, two backbone curve model parameters, and four bounding loop model parameters. To capture the seafloor stiffness degradation effect due to cyclic loading, a degradating P-y model was also developed. The degradating model proposes three degradation control parameters, which consider the effects of the number of cycles and cyclic unloading-reloading paths. Accumulated deflections serve as a measure of energy dissipation. The degradating model was also made up of three components. The first one was the backbone curve, same as the non-degradating model. The bounding loops define the P-y behavior of extreme loading deflections. The elastic rebound curve and partial separation stage were in the same formation as the non-degradating model. However, for the re-contact and re-loading curve, degradation effects were taken into the calculation. These two models were verified through comparisons with laboratory basin tests. Computer codes were also developed to implement these models for seafloor-riser interaction response.

A three-Dimensional deflection of the electron-beam resulting a missed joint due to thermoelectric magnetism generated in welding dissimilar metal is experi- mentally and analytically investigated. In theoretical analyisis a narrow welding cavity is assumed to be a paraboloid of revolution. Applying a three-dimensional analytical solution of thermolectric currents, magnetic fiux densities, and deflections of the electron beam are determined from Maxwell's electromagnetic equations. The computed magnetic fields,thermoelectric currents and beam deflection will be compared to experimental results. Factors affect-ing deflection are discussed. The major advantage of welding with a high-power-density-electron-beam is the ability to weld dissimilar metals, unfortunately, can be missed. when the beam from the electron gun is properly aligned with the joint, subsequent deflection of the beam can result in nonsymmetric fusion along a joint, or the fusion zone may miss the joint .One reason responsible for the beam deflection is due to thermoelectric magnetic fields. Since temperature gradients exist between the top and bottom and in front and be-hind the deep and narrow cavity ,thermoelectric currents due to the Seebeck effect are produced in dissimilar metals. The induced magnetic field above and below the top surface therefore deflects the electron-beam and induces a missed joint in S-shaped. In this study, experiments will be conducted to measure missed joints. A three-dimensional thermoelectric and heat conduction model is also to predict deflection of an electron-beam From the surroundings and to bulk workpieces, the entire trajectory of the beam can be determined.a more systematical and realistic understanding on missed joint parameters.

Thin target L-Shell x-ray production cross sections for protons incident on ₆₂Sm and ₇₀Yb in the energy range of 0.3 to 2.4 MeV/amu, alpha particles incident on ₆₂Sm, ₇₀Yb, and ₈₂Pb in the energy range of 0.15 to 4.8 MeV/amu, and lithium ions incident on ₅₈Ce, ₆₀Nd, ₆₂Sm, ₆₆Dy, ₆₇Ho, ₇₀Yb, and ₈₂Pb in the energy range of 0.8 to 4.4 MeV/amu have been measured. The cross section data have been compared to the planewave Born approximation (PWBA) and the PWBA modified to include binding energy and Coulomb deflection effects. The Lα₁,₂ x-ray production cross sections are best represented by the PWBA modified to include both the binding energy and Coulomb deflection effects (PWBA-BC) over the entire incident ion, incident energy, and target ranges studied. However, the Lγ₁ and Lγ₂,₃,₍₆₎ x-ray production cross sections are best represented by the PWBA except at the lower ion energies, where both the PWBA and PWBA-BC are in disagreement with the data. The comparison of Lα₁,₂/Lγ₂,₃,₍₆₎ ratios to theory reveals that the PWBA-BC does not predict the inflection point substantiated by the data, and the agreement between the data and the PWBA-BC becomes worse as the atomic number of the incident ion increases. Comparison of the PWBA modified to include binding energy effects CPWBA-B) and the PWBA modified to include Coulomb deflection effects (PWBA-C) to the Lα₁,₂, Lγ₁, and the Lγ₂,₃ cross sections for protons, alpha particles, and lithium ions incident on ₇₀Yb indicates that the PWBA-C overestimates the magnitude of the data but does describe the shape of the L₁-associated cross section while the PWBA-B underestimates the magnitude of the data but fails to predict the proper shape of the L₁-associated data. In order to evaluate the ability of the PWBA and the presently accepted modifications to the PWBA to fit the experimental data, future experimentation should be conducted in the energy range that includes the point where the ratio of the incident ion velocity to the L-Shell electron velocity is equal to 0.19 (i.e., V₁/Vₗ = 0.19). This is where the L₁-associated cross sections begin to exhibit the shouldered structure and the cross section ratios L₃/L₁ and L₂/L₁ have inflection points.

The non-destructive measurement of deflection basins has come a long way from measuring only maximum deflection or radius of curvature and using empirical relationships in rehabilitation design. New equipment was developed world-wide and analysis techniques moved towards utilising the full deflection basin in fundamental analysis procedures. This author addressed the problem of a proper description of the full deflection basin by doing a detailed literature survey on this subject. Various deflection basin parameters that describe the deflection basin are listed, as well as the various measuring apparatus related to them. The apparatus are all discussed in detail and related to the equipment available in South Africa. The measurement of deflection basins with the road surface deflectometer (RSD) under accelerated testing with the fleet of heavy vehicle simulators (HVSs) are described in detail. An improved data manipulation procedure is proposed which simplifies the calculation of all the deflection basin parameters found in literature. Various models to fit the measured deflection basins are also investigated in an effort to describe the deflection basin in full too. The measured deflection basin parameters of a bitumen, granular, cemented and light structured granular base pavement are discussed in detail as being tested with the fleet of HVS's. It is shown how the deflection basin parameters reflect the structural capacity of the various layers and behaviour states. A more accurate description of the behaviour states is made possible with the proposal of ranges for the various behaviour states for these deflection basins selected. A literature study was carried out to investigate the various analysis procedures that use measured deflection basins as basic input in the characterization of materials. On the basis of this study, linear elastic programmes were used to calculate effective elastic moduli for each pavement layer, using measured deflection basins as input. The possibility to relate typical distress determinants to measured deflection basins were investigated in the literature. Based on this, typical South African flexible pavement structures were analysed mechanistically and typical design curves were established for typical bitumen and. granular base pavements. The effect of overlays were investigated too, resulting in typical overlay design curves. In the final chapter the author endeavours to summarise the research by indicating how deflection basins can be measured and enhance the South African mechanistic rehabilitation design process. Only the latter rehabilitation design procedure is discussed with specific reference to the enhancement of the behaviour state identification, material characterization, analysis procedure and rehabilitation design with measured deflection basin parameters. The author ends off by giving an indication of the future research need in this field of deflection basins. / Thesis (PhD)--University of Pretoria, 2010. / Civil Engineering / unrestricted

In the past, research into Short Takeoff and Landing aircraft has led to the investigation of the coupling of a Circulation Control Wing and Upper Surface Blowing engine. The Circulation Control Wing entrains the flow of the engine to be deflected downward such that a component of the thrust is now in the vertical direction. The unfortunate consequence of the Upper Surface Blowing engine is the poor cruise performance due to scrub drag. Cal Poly's research into a Cruise Efficient Short Takeoff and Landing Aircraft offers a solution by pylon mounting over the wing engines. Analysis shows that the engine thrust is still deflected downward resulting in very high lift coefficients above 6.6. In the culmination of this project Cal Poly would like to find a correlation between the location of the engine and the deflection angle of the thrust. The results of this study show some engine deflection for an over the wing engine. The configurations explored were able to provide 3°-8.5° of deflection. The deflection falls short of the results by previous static and wind tunnel tests of upper surface blowing engines. The results show that the closer to the wing and further forward the engine is located the more engine deflection will be seen. This paper explores the trends of coupling an over the wing engine with a circulation control wing as well as compare the results to the idealized claims of previous experiments.

Indiana University-Purdue University Indianapolis (IUPUI) / Objectives: To investigate the effect of bulk-fill resin based composite materials on cuspal deflection in large slot mesio-occlusal-distal cavities (MOD) in premolar teeth. Methodology: Thirty-two sound maxillary premolar teeth with large slot MOD cavities were distributed to four groups (n=8). Three groups were restored with bulk-fill resin composite materials (Tetric EvoCeram, x-tra fil, and Sonic Fill, respectively) in a single increment. The conventional composite group, Filtek Z100, was used to restore the cavities in 2mm increments. Cusp deflection was recorded post irradiation using a Nikon measurescope UM-2 (Nikon, Tokyo, Japan), by measuring the changes in the bucco-palatal width of the premolar teeth at 5 minutes, 24 hours, and 48 hours after completion of the restoration. The cuspal deflection was obtained by recording the difference between the baseline measurements and the other measurements for each tooth. Results: Cuspal deflection was significantly higher in Conventional Composite than in Tetric EvoCeram Bulk Fill (p=0.0031), x-tra Fil Bulk (p=0.0029), and SonicFill Bulk (p=0.0002). There was no significant difference in cuspal deflection for Tetric EvoCeram Bulk, X-tra Fil Bulk, and SonicFill Bulk Composites. Conclusions: All the investigated bulk-fill resin composites exhibited cuspal deflection lower than conventional resin composite. One of the aims of research and studies on the resin composite materials is improving their clinical longevity, and simplifying their use. For that purpose bulk-fill materials are considered promising materials and further clinical studies should be conducted.

No description available.

The research presented in this thesis focusses on the experimental study of two fundamental questions: the crystal-to-glass transition and how aggregates of adhesive droplets spread on a surface. Aggregates made of lightly adhesive oil droplets are used as models for crystals or amorphous glasses. The force applied on the aggregates can be directly measured as they are compressed. A large portion of the work focusses on the crystal-to-glass transition and tries to answer the following question: how many defects are needed in a crystal for its mechanical response to be like a glass? To answer this question, the mechanical response of a perfect mono-crystal is measured. It is found that crystals deform elastically until they fail catastrophically in a single event once the force exceeds a critical value: the yield stress. The force measured during the compression of a crystal shows a well defined number of peaks which only depends on the initial geometry of the aggregate. As defects are added (the amount of disorder increased) the number of peaks in the force measurement increases rapidly before it saturates at a value obtained for model glasses. The magnitude of the force peaks also decreases as disorder is introduced. This work concludes that even a small amount of disorder in a crystal has a significant impact on its mechanical properties. In the second project, the spreading of a monodisperse aggregate of oil droplets is studied. Droplets are added one-by-one to a growing aggregate and the area covered on the interface is measured. It is found that after an initial 3D growth, the height of the aggregate saturates and the growth only happens in 2D along the horizontal direction. The growth is analogous to a puddle of liquid. In analogy with the capillary length in liquids, the ``granular capillary length" is introduced to characterize the balance between buoyancy acting on the droplets and the adhesion strength. The height of the aggregates, in the later stage of the growth, is set by this length scale. A method was developed to characterize the adhesion between two droplets, a key parameter in this experiment, as a function of the relevant experimental parameters. / Thesis / Doctor of Philosophy (PhD)

In this work a review of the technology surrounding high deflection strain sensing with an emphasis on that of a recently developed nickel nano-composite strain sensor is presented. A new base silicone material was identified for the nickel nano-composite strain sensor that improves its mechanical stiffness and conductive properties. A previously identified cyclic creep concern was mitigated through preconditioning and the use of adhered backing materials. Through a block design experiment the strain/resistance curves for the strain sensors were characterized over a wide range of nano-filler material compositions. An analytical model was developed based on observation that the resistance of the sensors follows a log-normal response with respect to applied strain. The model demonstrated high fidelity in representing the resistance-strain relationship of the sensors yielding an average R2 value of .93. A standard least squares statistical analysis confirmed strong relationships between curve fit parameters of the modified log-normal model and additive volume fractions with significance at the .05 level for each case. A suitable strain gauge composition was selected for a specific application: a fetal monitoring device. A prototype belt was developed that is worn over the abdomen to detect deflections cause by labor contractions and other fetal movements. Simulation testing on the device was performed and the device was found to be a feasible option for fetal monitoring.

Biological tissues routinely experience large strains and undergo large deformations during normal physiologic activity. Biological tissue deformation is well beyond the range of standard strain gauges, and hence must often be captured using expensive and non-portable options such as optical marker tracking methods that may rely upon significant post-processing. This study develops portable gauges that operate in real time and are compatible with the large strains seen by biological materials. The new gauges are based on a relatively new technique for quantifying large strain in real-time (up to 40 %) by use of a piezoresistive nano-composite strain gauge. The nano-composite strain gauges (NCSGs) are manufactured by suspending nickel nanostrands within a biocompatible silicone matrix. The conductive nickel filaments come into progressively stronger electrical contact with each other as the NCSG is strained, thus reducing the electrical resistance that is then measured using a four-probe method. This thesis summarizes progress in the understanding, design and application of NCSGs for biomechanical applications. The advanced understanding arises from a nano-junction-level finite element analysis of gap evolution that models how the geometry varies with strain in the critical regions between nickel particles. Future work will incorporate this new analysis into global models of the overall piezoresistive phenomenon. The improvements in design focused on the manufacturing route to obtain a reliable thin and flexible gauge, along with a modified connection and data extraction system to reduce drift issues that were present in all previous tests. Furthermore, a pottable data logging system was developed for mobile applications. Finally, a method of analyzing the resultant data was formulated, based upon cross-correlation techniques, in order to distinguish between characteristic wave-forms for distinct physical activities. All of these improvements were successfully demonstrated via a gait-tracking system applied to the insole of standard running shoes.