The transient two-dimensional thermocapillary convection and molten pool shape in melting or welding with a time-dependent and distributed incident flux are numerically predicted in this study. Determination of the molten pool shapes is crucial, because of its close relationships with the strength, microstructure, and mechanical properties of the fusion zone. In the work, the time-dependent incident flux is assumed to be a function of scanning speed and energy distribution parameter. Transport processes at the time corresponding to the maximum cross section can be identical to those under steady three-dimensional condition. The computed flow patterns and molten pool shapes under the flat free surface exhibits distinct regions for different Marangoni and Prandtl numbers. The effects of Peclet number and beam power on flow and temperature fields and fusion zone shapes are also presented. The computed results are confirmed by comparing the predicted peak speed on the free surface and molten pool width with those obtained from scale analysis provided in the literature.

A projected fringe profilometry (PFP) is an optical measurements technology which is widely used at present in gauging the object's three dimensional appearance. PFP is frequently used in detecting the quality of products in the industry due to the specialty of non-contact type, the short retrieve time and low environmental effect. As a result of the development for many years, PFP treats in the gauging static state of the object's three dimensional appearance has had the extremely fine gauging efficiency and the precision in , however in the dynamic inspected object in the gauging , not yet was still mature. If could to develop a set of gauging way in the dynamic inspected object , the application would be more widespread. Taking PFP as the gauging principle, analyzing the changes between the dynamic treat measured object and the fringe. Using the simple mathematics to describe the interaction relations between the fringe and the inspected the object. Finally, reconstructed the inspected object' three dimensional appearance. May know biggest superiority by the experimental process, in the situation of without losing the information of fringe, PFP can reconstruct the inspected object' three dimensional appearance and do not need the motion condition information.

Thesis (M.S.)--Auburn University, 2008. / Abstract. Vita. Includes bibliographical references (p. 65-68).

Thesis (Ph. D.)--University of Washington, 2002. / Vita. Includes bibliographical references (leaves 130-134).

Thesis (M.S. in Mechanical Engineering)--Naval Postgraduate School, March 2004. / Thesis advisor(s): Indranath Dutta. Includes bibliographical references (p. 45-47). Also available online.

This project explores how to use concatenated shapes as a way of creating inconstant garment constructions. The process starts wide by both testing chains, stitching and knots. But narrows down along the way to only focus on linked shapes without the use of stitches or glue. Different materials and shapes is tested to find a construction that not only hold together but also gives the user playfulness and the opportunity to easily change their own garment. Various forms were tested to be linked together, such as circle, rectangle, square, but also asymmetrical shapes. A choice was made to only focus on the circle to make the design process as focused as possible. Different ways in how to link the circle was tested, different scales, materials and colours. However did this round shape reach the end of the road and the investiga- tion resulted limited. In order to bring the project forward was the circle put aside. The process continued instead with classic clothing design as the basis for the shapes. This shapes resulted in a better variety and stronger garment reference. It opens up for more ways of concatenating garments and textile opportunities that are not restricted by the technique. Pieces that can be assembled in different ways by the user gives the wearer the opportunity to change the expression without buying a new garment. The pieces are also easier to recycle when there is no seams, zippers or other trimmings.

Grasping can be a complicated process for robotics due to the replication of human fine motor skills and typically high degrees of freedom in robotic hands. Robotic hands that are underactuated provide a method by which grasps can be executed without the onerous task of calculating every fingertip placement. The general shape configuration modes available to underactuated hands lend themselves well to an approach of grasping by shape primitives, and especially so when applied to gloveboxes in the nuclear domain due to the finite number of objects anticipated and the safe assumption that objects in the set are rigid. Thus, the object set found in a glovebox can be categorized as a small set of primitives such as cylinders, cubes, and bowls/hemispheres, etc. These same assumptions can also be leveraged for reliable identification and pose estimation within a glovebox. This effort develops and simulates a simple, but robust and effective grasp planning algorithm for a 7DOF industrial robot and three fingered dexterous, but underactuated robotic hand. The proposed grasping algorithm creates a grasp by generating a vector to the object from the base of the robot and manipulating that vector to be in a suitable starting location for a grasp. The grasp preshapes are selected to match shape primitives and are built-in to the Robotiq gripper used for algorithm demonstration purposes. If a grasp is found to be unsuitable via an inverse kinematics solution check, the algorithm procedurally generates additional grasps to try based on object geometry until a solution can be found or all possibilities are exhausted. The algorithm was tested and found capable of generating valid grasps for visually identified objects, and can recalculate grasps if one is found to be incompatible with the current kinematics of the robotic arm. / text

The flow of fluids over solid surfaces is an integral part of many technologies, and the analysis of such flows is important to the design and operation of these technologies. Solid surfaces, however, are generally rough at some scale, and analyzing the effects of such roughness on fluid flows represents a significant challenge. There are two fluid flow situations in which roughness is particularly important, because the fluid shear layers they create can be very thin, of order the height of the roughness. These are very high Reynolds number turbulent wall-bounded flows (the viscous wall layer is very thin), and very low Reynolds number lubrication flows (the lubrication layer between moving surfaces is very thin). Analysis in both of these flow domains has long accounted for roughness through empirical adjustments to the smooth-wall analysis, with empirical parameters describing the fluid dynamic roughness effects. The ability to determine these effects from a topographic description of the roughness is limited (lubrication) or non-existent (turbulence). The commonly used parameter, the equivalent sand grain roughness, can be determined in terms of the change in the rate of viscous energy dissipation caused by the roughness and is generally obtained by measuring the effects on a fluid flow. However, determining fluid dynamic effects from roughness characteristics is critical to effective engineering analysis. Characterization of this mapping from roughness topography to fluid dynamic impact is the main topic of the dissertation. Using the mathematical tools of shape calculus, we construct this mapping by defining the roughness functional and derive its first- and second- order shape derivatives, i.e., the derivatives of the roughness functional with respect to the roughness topography. The results of the shape gradient and complete spectrum of the shape Hessian are presented for the low Reynolds number lubrication flows. Flow predictions based on this derivative information is shown to be very accurate for small roughness. However, for the study of high Reynolds number turbulent flows, the direct extension of the current approach fails due to the chaotic nature of turbulent flows. Challenges and possible approaches are discussed for the turbulence problem as well as a model problem, the sensitivity analysis of the Lorenz system. / text

published_or_final_version / Statistics / Master / Master of Philosophy

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