Global ETD Search
Search theses and dissertations gathered from participating repositories worldwide. Every result links back to the library that holds it. No account is needed.
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Showing 1 to 20 of 20 for “"negative gradient"”.
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Moduli spaces and cw structures arising from morse theory
… and f is a Morse function on it. We consider the negative gradient flow of f. Suppose the flow satisfies transversality. This naturally defines the moduli spaces of flow lines and gives a stratication of M by its unstable manifolds. The gluing of broken flow lines can also be constructed.</p> …
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Variational Methods on Elastic Curves
… by evolving curves in the direction of the negative gradient in certain Hilbert space settings. By discretizing the curves and using numerical integration, we compute approximate minimizers and display using computer graphics. We propose a conjecture based on the rotation number of a curve …
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Design Optimization of Fuzzy Logic Systems
… The step-size along the update direction (e.g., negative gradient or deflected negative gradient) is chosen according to a criterion of minimum distance from the vertex of the quadratic model. This approach rescales the complexity in the step-size selection from the order of the (large) number of …
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Methods of non-linear least squares estimation
… Gauss-Newton or Taylor Series methods), 2) gradient techniques - use of the negative gradient of the sum of squares function (includes the well-known Method of Steepest Descent), 3) combination techniques - attempts to gain an improved rate of convergence through a combination of the above …
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Path planning using the Newtonian potential
… representation and the guidance provided by the negative gradient of the potential field in the form of repulsive forces. In this thesis, a Newtonian potential function is used to represent planar polygonal objects and obstacles. The closed-form expression of this potential field as well as some …
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Feedback control of separation in unsteady flows
… friction (or wall shear) vanishes and admits a negative gradient. Despite initial suggestions, however, it was recognized that Prandtl's zero-skin-friction criterion for separation is invalid for unsteady flows. Employing a Lagrangian approach, Haller (2004) derived an exact kinematic theory for …
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Melt generation in the Earth's mantle at Convergent Plate Margins
… of the mantle may be responsible for the large negative gradient in seismic wave speed observed at the lithosphere-asthenosphere boundary below eastern North America. These studies together advance our knowledge of how the recycling of tectonics plates on Earth affects melt generation in the …
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Nonlinear dynamics of three dimensional fluid flow separation
… where the wall shear vanishes and admits a negative gradient. Three-dimensional flows, however, tend to separate along lines, as opposed to isolated wall-shear zeros. Despite widespread effort, no generally applicable extension of Prandtl's result has emerged for even three-dimensional …
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Mechanical and metallurgical properties of dissimilar metal joints using novel joining techniques
… transfer joints are a linear relationship with a negative gradient to value of the root angle on the mild steel side of the joints, as the angle at the root decreases the fatigue life increases. It was found that when joining the material combinations outlined in this research with Laser Hybrid …
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Analysis of two- and three-dimensional flow separation
… friction (or wall shear) vanishes and admits a negative gradient. Although commonly thought otherwise, these separation conditions are purely kinematic: They can be derived for any two-dimensional steady vector field that conserves mass (see, e.g. Shariff, Pulliam, and Ottino 1991). Haller …
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An optimally adjusted TCUL controller for the projection of underground transmission lines
… improvement in the system performance. A negative gradient optimization routine is used to determine the required adjustment. A derivation of the adjoint network relationships for a phase-angle-connected transformer is given. These relationships provide a means for readily determining the …
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Accuracy-aware privacy mechanisms for distributed computation
… This step is followed by descent along the negative gradient of the local cost function. We show that if the graph of non-adversarial agents is connected and non-bipartite, then our algorithm keeps private local cost information non-identifiable while asymptotically converging to the …
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Enhanced imaging of deep lithospheric and shallow near surface structures through innovations in seismic interferometry and array processing.
… as a PpP-type reflection response from a sharp, negative velocity gradient at the Lithosphere-Asthenosphere Boundary (LAB) at approximately 90 km depth. The detection of this event in a relatively high-frequency band, combined with its positive polarity in autocorrelograms, indicates a steep …
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Model realization using sensitivity functions
… the device modeling problem from an error gradient minimization viewpoint. This leads to the attainment of a minimal index of performance function (IP) and, consequently, emulates a desired device model response either in the frequency or time domain. In the frequency domain the problem of …
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Design and development of a sensory feedback system for transradial amputees using body powered prostheses
… also improved illustrated by a significantly negative relationship (negative gradient) in all trend lines over the period of testing. This suggests a learnability with the device: as the user becomes more cognisant of the device, the better their performance is in accuracy and response time. …
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Turbulence Structure Of Plane Surface Jets In A Current
… The free surface adjusted the pressure gradient and maintained self-similarity in the present experiments. This trend of self-similarity of velocity profiles deviated from the Gaussian distribution in the fully-developed region of surface jets. The self-similar near Gaussian velocity …
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A Parallel-In-Time Gradient-Type Method For Optimal Control Problems
… proposes and analyzes a new parallel-in-time gradient-type method for time-dependent optimal control problems. When the classical gradient method is applied to time-dependent optimal control problems, each iteration requires the forward solution of the state equations followed by the backward …
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Large Scale Online Aggregation Via Distributed Systems
… In the second project, I consider implementing gradient descent on top of MapReduce. Gradient descent is an optimization algorithm that finds the local minima of a function L(w) by starting with an initial point $w_0$ and then taking steps in direction of negative gradient of the function to be …
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A study of the remineralization of organic carbon in nearshore sediments using carbon isotopes
… of pore water collected seasonally show large gradients with depth, which are larger in summer than in winter. The δ13C (PDB) of ΣCO2 varies from 1.3 o/oo in the bottom water to approximately -10 o/oo at 30 cm. During all seasons, there was a trend towards more negative values with depth in the …
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A study of the remineralization of organic carbon in nearshore sediments using carbon isotopes
… of pore water collected seasonally show large gradients with depth, which are larger in summer than in winter. The 613C (PDB) of IC02 varies from 1.3 o/oo in the bottom water to approximately -10 o/oo at 30 cm. During all seasons, there was a trend towards more negative values with depth in the …