An algorithm based on Semi-Definite Programming (SDP) formulation is proposed for optimum design for specified linear buckling load factor. Optimal trusses and frames are computed by using the primal-dual interior-point method for SDP. It is well known that optimizing structures under buckling constraints is difficult because of nondifferentiability of the buckling load factors for the case of ...

We present experiments on the dynamic buckling and fragmentation of slender rods axially impacted by a projectile. By combining the results of Saint-Venant and elastic beam theory, we derive a preferred wavelength lambda for the buckling instability, and experimentally verify the resulting scaling law for a range of materials including teflon, dry pasta, glass, and steel. For brittle materials,...

The sinusoidal speech model represents a speech signal as a linear combination of sinusoids with time-varying parameters {amplitudes, frequencies, and phases}. However, one drawback of this model is that the analysis window width is generally fixed in analyzing the signal. Since each sinusoidal parameter has different frequencies, an analysis window with fixed width can’t guarantee an optimum s...

BACKGROUND Tortuous arteries are often seen in patients with hypertension and atherosclerosis. While the mechanical stress in atherosclerotic plaque under lumen pressure has been studied extensively, the mechanical stability of atherosclerotic arteries and subsequent effect on the plaque stress remain unknown. To this end, we investigated the buckling and post-buckling behavior of model stenoti...

For the first time, we report on methods to control and prevent polymer films from buckling. Buckled morphologies were created by thermally cycling or mechanically compressing a poly(dimethylsiloxane) substrate coated with a polyelectrolyte multilayer film. By variation of the dimensions of the surface topography relative to the buckling wavelength (e.g., pattern size is less than, equal to, an...

The problem of a thin spherical linearly-elastic shell, perfectly bonded to an infinite linearly-elastic medium is considered. A constant axisymmetric stress field is applied at infinity in the matrix, and the displacement and stress fields in the shell and matrix are evaluated by means of harmonic potential functions. In order to examine the stability of this solution, the buckling problem of ...

The buckling of compressively-loaded members is one of the most important factors limiting the overall strength and stability of a structure. I have developed novel techniques for using active control to wiggle a structural element in such a way that buckling is prevented. I present the results of analysis, simulation, and experimentation to show that buckling can be prevented through computer-...

In this paper, we address the estimation of the parameters of the two dimensional sinusoidal signal model. The proposed method is the two dimensional extension of the one dimensional noise space decomposition method. The proposed methods provide consistent estimators of the unknown parameters and they are non-iterative in nature. We propose a pairing algorithm also, which helps in identifying t...

ABSTRACT: Probability theory is applied to the problem of estimating the amplitudes of the sinusoids in nuclear magnetic resonance data containing two exponentially decaying sinusoids. The posterior probability-density of one of the amplitudes is derived independent of the phases, frequencies, decay-rate constants, variance of the noise, and the amplitude of the other sinusoid. This probability...

Hollow sections have been widely used for steel structures. Applications of High Strength Steel (HSS) on cold-formed hollow sections lead to thinner and lighter structures. This paper presents numerical investigations on the lateral-torsional buckling resistance of the cold-formed high strength steel rectangular hollow beam. Results from finite element analysis using Abaqus software are compare...