1,542 research outputs found
Towards Gradient-Based Design Optimization of Flexible Transport Aircraft with Flutter Constraints
Peer Reviewedhttps://deepblue.lib.umich.edu/bitstream/2027.42/140443/1/6.2014-2726.pd
Effective-mass Klein-Gordon Equation for non-PT/non-Hermitian Generalized Morse Potential
The one-dimensional effective-mass Klein-Gordon equation for the real, and
non-\textrm{PT}-symmetric/non-Hermitian generalized Morse potential is solved
by taking a series expansion for the wave function. The energy eigenvalues, and
the corresponding eigenfunctions are obtained. They are also calculated for the
constant mass case.Comment: 14 page
Solitary coherent structures in viscoelastic shear flow: computation and mechanism
Starting from stationary bifurcations in Couette-Dean flow, we compute
nontrivial stationary solutions in inertialess viscoelastic circular Couette
flow. These solutions are strongly localized vortex pairs, exist at arbitrarily
large wavelengths, and show hysteresis in the Weissenberg number, similar to
experimentally observed ``diwhirl'' patterns. Based on the computed velocity
and stress fields, we elucidate a heuristic, fully nonlinear mechanism for
these flows. We propose that these localized, fully nonlinear structures
comprise fundamental building blocks for complex spatiotemporal dynamics in the
flow of elastic liquids.Comment: 5 pages text and 4 figures. Submitted to Physical Review Letter
Evaluation of DNA polymorphism in the Red Sea Epinephelus species using 12s rRNA and inter simple sequence repeats
1197-1205The true phylogenetic relation among Epinephelus species is under debate. The present investigation was designed for evaluation of DNA polymorphism in some Red sea Epinephelus species using 12s rRNA and Inter Simple Sequence repeats. DNA polymorphism values were detected and evaluated within all estimated fishes. Both applied techniques revealed that E. malabaricus is closely related to E. summana. The distance value between E. chlorostigma and E. areolatus is lower than the distance value between E. chlorostigma and E. radiatus. The Serranidae evolutionary variations were evaluated comparatively with other ray-finned fishes belonging to four fish genera (Carangidae, Labridae, Mugilidae and Cichlidae) based on 12s rRNA sequence variations (obtained from NCBI). The developed DNA markers were reliably branched in the evaluated fishes. More molecular investigations using more spatial and temporal fish samples should be carried out in the future for exploring the true Epinephelus species biodiversity in the Red sea
Robust Dropping Criteria for F-norm Minimization Based Sparse Approximate Inverse Preconditioning
Dropping tolerance criteria play a central role in Sparse Approximate Inverse
preconditioning. Such criteria have received, however, little attention and
have been treated heuristically in the following manner: If the size of an
entry is below some empirically small positive quantity, then it is set to
zero. The meaning of "small" is vague and has not been considered rigorously.
It has not been clear how dropping tolerances affect the quality and
effectiveness of a preconditioner . In this paper, we focus on the adaptive
Power Sparse Approximate Inverse algorithm and establish a mathematical theory
on robust selection criteria for dropping tolerances. Using the theory, we
derive an adaptive dropping criterion that is used to drop entries of small
magnitude dynamically during the setup process of . The proposed criterion
enables us to make both as sparse as possible as well as to be of
comparable quality to the potentially denser matrix which is obtained without
dropping. As a byproduct, the theory applies to static F-norm minimization
based preconditioning procedures, and a similar dropping criterion is given
that can be used to sparsify a matrix after it has been computed by a static
sparse approximate inverse procedure. In contrast to the adaptive procedure,
dropping in the static procedure does not reduce the setup time of the matrix
but makes the application of the sparser for Krylov iterations cheaper.
Numerical experiments reported confirm the theory and illustrate the robustness
and effectiveness of the dropping criteria.Comment: 27 pages, 2 figure
On Inner Iterations in the Shift-Invert Residual Arnoldi Method and the Jacobi--Davidson Method
Using a new analysis approach, we establish a general convergence theory of
the Shift-Invert Residual Arnoldi (SIRA) method for computing a simple
eigenvalue nearest to a given target and the associated eigenvector.
In SIRA, a subspace expansion vector at each step is obtained by solving a
certain inner linear system. We prove that the inexact SIRA method mimics the
exact SIRA well, that is, the former uses almost the same outer iterations to
achieve the convergence as the latter does if all the inner linear systems are
iteratively solved with {\em low} or {\em modest} accuracy during outer
iterations. Based on the theory, we design practical stopping criteria for
inner solves. Our analysis is on one step expansion of subspace and the
approach applies to the Jacobi--Davidson (JD) method with the fixed target
as well, and a similar general convergence theory is obtained for it.
Numerical experiments confirm our theory and demonstrate that the inexact SIRA
and JD are similarly effective and are considerably superior to the inexact
SIA.Comment: 20 pages, 8 figure
Effect of Stretchable Circuit Deformation on Its Electrical Performance for Automotive Lighting Application / M. F. M. Sharif...[et al.]
The purpose of this paper is to investigate the effect of the stretchable circuit deformation during a thermoforming process on its electrical performance for automotive lighting. The thermoforming process was carried out using a mould that was developed based on commercially available automotive lighting product. The circuit was printed on a 2-D thermoplastic substrate using screen printing technique before transformed into 3-D shape through the thermoforming process followed by LEDs assembly. The quality of the product were characterised before and after the thermoforming process by measuring the resistance and resistivity of the circuit. Voltage drops and luminance each of the LEDs resulted from the deformation of the circuit were compared with the current automotive lighting product. The study shows that the new design with stretchable material has similar performance with previous design in terms of electrical performance. These findings will encourage further development of new design of automotive lighting in the future
On Convergence of the Inexact Rayleigh Quotient Iteration with the Lanczos Method Used for Solving Linear Systems
For the Hermitian inexact Rayleigh quotient iteration (RQI), the author has
established new local general convergence results, independent of iterative
solvers for inner linear systems. The theory shows that the method locally
converges quadratically under a new condition, called the uniform positiveness
condition. In this paper we first consider the local convergence of the inexact
RQI with the unpreconditioned Lanczos method for the linear systems. Some
attractive properties are derived for the residuals, whose norms are
's, of the linear systems obtained by the Lanczos method. Based on
them and the new general convergence results, we make a refined analysis and
establish new local convergence results. It is proved that the inexact RQI with
Lanczos converges quadratically provided that with a
constant . The method is guaranteed to converge linearly provided
that is bounded by a small multiple of the reciprocal of the
residual norm of the current approximate eigenpair. The results are
fundamentally different from the existing convergence results that always
require , and they have a strong impact on effective
implementations of the method. We extend the new theory to the inexact RQI with
a tuned preconditioned Lanczos for the linear systems. Based on the new theory,
we can design practical criteria to control to achieve quadratic
convergence and implement the method more effectively than ever before.
Numerical experiments confirm our theory.Comment: 20 pages, 8 figures. arXiv admin note: text overlap with
arXiv:0906.223
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