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 276 for “"concave"”.
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Combinatorial optimization problems with concave costs
… we study the problem of minimizing a separable concave function over a polyhedron. We assume the concave functions are nonnegative nondecreasing on R+, and the polyhedron is in RI' (these assumptions can be relaxed further under suitable technical conditions). We show how to approximate this …
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Maximum likelihood estimation of a multivariate log-concave density
… specifically log-concavity. The class of log-concave densities includes many common parametric families and has desirable properties. For univariate data, these estimators are relatively well understood, and are gaining in popularity in theory and practice. We discuss extensions for …
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Unimodal, log-concave and Pólya frequency sequences in combinatorics
Thesis (Ph. D.)--Massachusetts Institute of Technology, Dept. of Mathematics, 1988.
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An optimization perspective on log-concave sampling and beyond
… guarantees for high-accuracy log-concave sampling; the first lower bounds for the complexity of log-concave sampling; an analysis of mirror Langevin Monte Carlo for constrained sampling; and the development of a theory of approximate first-order stationarity in non-log-concave …
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Shape-Constrained Inference for Concave-Transformed Densities and their Modes
… constraints based on concavity. We consider log-concave densities and other “concave-transformed” densities on the real line, where a concave-transformed class is one given by applying a transformation (e.g. the logarithm or a power function) to concave functions. We expect our proofs and results …
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The morphology of the Kakumbi concave bank bench on Luangwa river
… investigates the formation and development of concave bank benches on the Luangwa River in Eastern Zambia. The Kakumbi concave bank bench is studied in greater detail than the other two benches because of its accessibility and some of its interesting characteristics.The morphology and internal …
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Étude aérodynamique d'un jet turbulent impactant une paroi concave
"Cette étude a donc pour but de poursuivre l'enquête de l'aérodynamique oscillatoire des jets impactant des parois courbes, mais pour un régime d'écoulement transitoire, turbulent, tridimentionnel. Les nombres de Reynolds utilisés dans l'étude numérique, basés sur le diamètre du jet …
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Finite Algorithms for Global Optimization of Concave Programs and General Quadratic Programs
This document examines finiteness issues in the context of structured global optimization problems. Specific aspects of this research include: (1) Development of finite algorithms, (2) Analysis of the algorithms' computational complexity, (3) Demonstrating the efficiency of the algorithms in …
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On the Complexity of Nonconvex-Strongly-Concave Smooth Minimax Optimization Using First-Order Methods
… When the objective function is convex-concave, almost the full picture is known. However, the general nonconvex-concave setting is less understood. In this work, we study the complexity of nonconvex-strongly-concave minimax optimization using first-order methods. First, we provide a …
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Étude aérodynamique et du transfert thermique d'un jet bidimentionnel impactant une paroi concave
… d'une aube de turbine à gaz, cette surface est concave. Des études ont montré que pour une certaine gamme du nombre de Reynolds, un jet injecté dans une cavité peut entrer dans un mouvement oscillatoire. Ce phénomène s'appelle battement du jet. Le but de cette étude est d'étudier …
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Non-Concave Programming and Differential Games in Dynamic Resource Allocation Models (Nash Equilibrium, Economic Growth)
… sum of discounted utilities subject to a convex-concave production function. The second essay, entitled "A Complete Characterization of Nash Equilibria in a Dynamic Resource Allocation Model," considers two agents, each trying to maximize the sum of his own discounted utilities subject to the …
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The response of concave singly curved fibre reinforced moulded sandwich and laminated composite panels to blast loading
… reports on the effect of air-blast loading on concave, singly curved fibre reinforced sandwich and composite panels. Sandwich panels and equivalent mass glass fibre laminates were manufactured and tested. Three types of curvature namely a flat panel (with infinite curvature), a curvature of …
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Bandwidth Selection for Level Set Estimation in the Context of Regression and a Simulation Study for Non Parametric Level Set Estimation When the Density Is Log-Concave
… where the density is estimated with a log-concave mixed model. We focus in particular on univariate densities and compare this method against a kernel plug-in estimator. The bandwidth for the kernel plug-in estimator is chosen optimally for the HDR problem. We observe through simulations …
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Histopathologische Untersuchungen von Aneurysmen der Aorta ascendens in Abhängigkeit von Aortenklappenvitien
… were obtained and divided into their convex and concave half during aortic surgery. Aortic surgery was indicated due to AAA in association to AS (AS-AAA group: n = 43) or AR (AR-AAA group: n = 41). Both groups contained 19 patients with TAV. Convex and concave halves of all samples were stained …
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Shaping of membranes by arc-like particles
… surface, and the particles as segmented arcs. Concave arc-like particles, i.e. particles interacting with the membrane on their concave side, shape membranes by inducing positive curvature at their binding sites. The membrane shape strongly depends on the overall angle and area concentration of …
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Curvature effects on the stability of three-dimensional laminar boundary layers
… number and sweep angle on an airfoil with a concave cutout in the leading edge region of the lower surface. It is known that convex curvature has a stabilizing effect on the laminar boundary layer. Conversely, concave curvature has a destabilizing effect. The magnitude of these effects for …
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Effects of gravity on equilibrium crystal shapes
… crystal passes from one region to another, being concave where P<sub>eff</sub> < 0, and convex where P<sub>eff</sub> > 0. In all cases it was possible to express the corresponding ECS in terms of the gravity-free one. For the hung crystal, i.e., a crystal pinned to a vertical wall at the top, it …
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Numerical investigation of the edge profile in hot-rolling
… edges is important. During the initial passes a concave profile develops - the material near the surfaces spreads outward while the material at the centre moves inward. The concave profile can lead to defects in the final product; these are the 'roll over' of material from the edges to the top …
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