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 42 for “"unsymmetric"”.
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Deformations of Unsymmetric Composite Panels
This work discusses the deformations of various unsymmetric composite panels due to thermal and mechanical loads. Chapter 2 focuses on the warpage of large unsymmetric curved composite panels due manufacturing anomalies. These panels are subjected to a temperature change of -280°F to simulate the …
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SMA-Induced Deformations In general Unsymmetric Laminates
General unsymmetric laminates exhibit large natural curvatures at room temperature. Additionally, inherent to most unsymmetric laminates is the presence of two stable configurations. Multiple configurations and stability issues arise because of the geometric nonlinearities associated with the large …
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Characterization of Bistability Behavior in Unsymmetric CFRP Laminates
<p>Composite laminates of unsymmetric layup families often exhibit twin stable shapes at room temperature, a phenomenon known as bistability. Unsymmetric bistable composite laminates have often been suggested for applications in aerospace morphing structures, damping, and energy storage, because of …
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Nonlinear Analysis of Unsymmetric Laminates under Cylindrical Bending
<p>Nonlinear analysis of unsymmetric composite long, narrow laminates under cylindrical bending is studied. The nonlinear governing equations are obtained to analyze the cylindrical bending of arbitrary laminates. The <em>von-Karman</em> type geometrical nonlinearity is incorporated in the …
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A parallel algorithm for sparse unsymmetric LU factorization
… for the direct LU factorization of general unsymmetric sparse matrices. The algorithm, D2, is based on a new nondeterministic parallel pivot search that finds a compatible pivot set S of size m, followed by a parallel rank-m update. These two steps alternate until switching to dense matrix …
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SMA-induced deformations in unsymmetric cross-ply laminates
… for predicting SMA-induced deformations in an unsymmetric cross ply laminate. A previously developed theory is used to predict the room-temperature shape of the cross-ply laminate by minimizing its total potential energy. Then, using the principle of virtual work, equations relating the shape …
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On the stability of certain two-dimensional unsymmetric parallel flows
Thesis (Ph.D.) Massachusetts Institute of Technology. Dept. of Mathematics, 1949.
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Buckling and postbuckling behavior of unbalanced and unsymmetric laminated graphite/epoxy plates
Thesis (Ph. D.)--Massachusetts Institute of Technology, Dept. of Aeronautics and Astronautics, 1986.
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Use of Piezoelectric Actuators to Effect Snap-Through Behavior of Unsymmetric Composite Laminates
… to effect snap-through behavior of simple unsymmetric cross-ply composite laminates is examined. Many unsymmetric laminates have more than one stable room-temperature shape and can be snapped through from one stable shape to another. In this new concept for morphing structures, one or more …
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Investigation of nonlinear crack tip deformation including the effects of unsymmetric spatial variations of material properties
An extensive investigation of non-uniform material effects on static fracture analyses is undertaken. Included in the study are theoretical, experimental and numerical techniques of focusing attention on the nonsymmetric deformation fields around a crack tip in a non-uniform yield strength varying …
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Deformations of In-plane Loaded Unsymmetrically Laminated Composite Plates
This study focuses on the response of flat unsymmetric laminates to an inplane compressive loading that for symmetric laminates are of sufficient magnitude to cause bifurcation buckling, postbuckling, and secondary buckling behavior. In particular, the purpose of this study is to investigate …
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An analysis of interlaminar stresses in unsymmetrically laminated plates
… numerical study of interlaminar stresses within unsymmetrically laminated plates is presented. The focus of the study is upon the linear thermoelastic response of thin square laminated composite plates subjected to extensional, compressive, or thermal loading. Symmetric and unsymmetric 0/90, …
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Some new results for solving linear systems arising from computational fluid dynamics problems
… systems (positive definite or indefinite), and unsymmetric systems. These systems are related, and all of them arise from the numerical solution of partial differential equations. For saddle-point problems, we introduce a class of expansion methods based on a new solution representation of the …
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Approximation of the Scattering Amplitude using Nonsymmetric Saddle Point Matrices
… We use a conjugate gradient-like iteration for a unsymmetric saddle point matrix that is contructed so as to have a real positive spectrum. We find that this method is more consistent than known methods for computing the scattering amplitude such as GLSQR or QMR. Then, we use techniques from …
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A comparative study of modified passenger railway vehicle trucks
… truck with yaw damper ( CD truck ) and (iv) Unsymmetric Suspension truck with yaw damper ( USD truck ). The USD truck has longitudinal asymmetry in the suspension according to direction of motion i.e. the primary stiffness in the leading axle is different from the trailing axle. Another truck …
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Studies on polygermanyl-transition metal (carbonyl) derivatives
… to be a useful synthetic route to yield the unsymmetric iron compound Ge₂H₅(GeH₃)Fe(CO)₄ and possibly GeH₃ (SiH₃)Fe(CO)₄. The polygermanyl-transition metal carbonyl derivatives are shown to be more stable than the germyl analogues and reasons, with spectroscopic evidence, are discussed.
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Synthetic and mechanistic study of catalytic dintrogen reduction
… reduction to ammonia, only the most bulky unsymmetric "hybrid" compounds can facilitate this reaction. Further study of these systems reveals a different pathway for catalyst failure than had previously been observed. It was discovered that, at least for the smaller ligands, a …
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Matrix-free time-domain methods for general electromagnetic analysis
… to ensure the stability for simulating an unsymmetrical numerical system, while preserving the matrix-free merit of the proposed method. This time-marching scheme is then made unconditionally stable, and hence allowing for the use of an arbitrarily large time step without sacrificing the …
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Adaptive finite element simulation of incompressible viscous flow
… the conjugate gradient method is used. For an unsymmetric stiffness matrix, the bi-conjugate gradient method is used. Both iterative solution methods make use of a diagonal preconditioning method (Jacobi preconditioning). Several problems are solved using this segregated method. In …
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Early transitional metal alkyl, alkylidene, and alkylidyne chemistry
… Zirconium and hafnium complexes of several new unsymmetric diamide ligands have been prepared and their proficiency in olefin polymerization reactions evaluated. The first set of supporting ligands examined are diamido-donor ligands that contain ethylene/o-phenylene "arms" and a …
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