Wei Gao¹, Chongmin Song¹, Francis Tin-Loi¹

CMES-Computer Modeling in Engineering & Sciences, Vol.46, No.2, pp. 151-190, 2009, DOI:10.3970/cmes.2009.046.151

Abstract Static response and reliability of structures with a mixture of random and interval parameters under uncertain loads are investigated in this paper. Structural stiffness matrix is a random interval matrix when some structural parameters are modeled as random variables and others are considered as intervals. The structural displacement and stress responses are also random interval variables. From the static finite element governing equations, the random interval structural responses are obtained using the random interval perturbation method based on the first- and second-order perturbations. The expressions for mean value and standard deviation of random interval structural More >

S S Panda¹, C S Manohar^1,2

CMES-Computer Modeling in Engineering & Sciences, Vol.28, No.3, pp. 161-184, 2008, DOI:10.3970/cmes.2008.028.161

Abstract The problem of reliability analysis of randomly parametered, linear (or) nonlinear, structures subjected to static and (or) dynamic loads is considered. A deterministic finite element model for the structure to analyze sample realization of the structure is assumed to be available. The reliability analysis is carried out within the framework of response surface methods which involves the construction of surrogate models for performance functions to be employed in reliability calculations. This construction, in the present study, has involved combining space filling optimal Latin hypercube sampling, kriging models and methods from data-based asymptotic extreme value modeling More >

B Radhika¹, S S P,a¹, C S Manohar^1,2

CMES-Computer Modeling in Engineering & Sciences, Vol.27, No.1&2, pp. 79-110, 2008, DOI:10.3970/cmes.2008.027.079

Abstract Reliability of nonlinear vibrating systems under stochastic excitations is investigated using a two-stage Monte Carlo simulation strategy. For systems with white noise excitation, the governing equations of motion are interpreted as a set of Ito stochastic differential equations. It is assumed that the probability distribution of the maximum in the steady state response belongs to the basin of attraction of one of the classical asymptotic extreme value distributions. The first stage of the solution strategy consists of selection of the form of the extreme value distribution based on hypothesis tests, and the next stage involves More >

V.C. Santos¹, P.S. Lopes¹, R. Gärtner², A.B. Jorge¹

The International Conference on Computational & Experimental Engineering and Sciences, Vol.4, No.2, pp. 53-58, 2007, DOI:10.3970/icces.2007.004.053

Abstract This work presents an approach for weight and reliability optimization of aeronautical armors. Military and police helicopters are usually exposed to highly risky situations, with a high probability for these aircrafts to be hit by projectiles. In this context, floor aircraft armor can be used to protect the crews' lives. However, the armoring of an aircraft causes an increase in weight. If this extra weight is poorly arranged, the changes in aircraft centroid position may even destabilize the aircraft. Thus, it is essential to design an armor not only to protect the aircraft, but also… More >

M. Manjuprasad¹, C. S. Manohar²

CMES-Computer Modeling in Engineering & Sciences, Vol.19, No.1, pp. 23-54, 2007, DOI:10.3970/cmes.2007.019.023

Abstract A technique for adaptive random field refinement for stochastic finite element reliability analysis of structures is presented in this paper. Refinement indicator based on global importance measures are proposed and used for carrying out adaptive random field mesh refinements. Reliability index based error indicator is proposed and used for assessing the percentage error in the estimation of notional failure probability. Adaptive mesh refinement is carried out using hierarchical graded mesh obtained through bisection of elements. Spatially varying stochastic system parameters (such as Young's modulus and mass density) and load parameters are modeled in general as… More >

P. Bocchini, C. Gentilini, F. Ubertini, E. Viola¹

Structural Durability & Health Monitoring, Vol.2, No.2, pp. 109-122, 2006, DOI:10.3970/sdhm.2006.002.109

Abstract This paper provides a simple and reliable method for the probabilistic characterization of the linear elastic response of frame structures with edge cracks of uncertain depth and location. A statistical analysis of the structural response allows consideration of the reliability of the investigated structure. A numerical example provides an indication of the performance of the approach proposed. More >

A. Soprano¹, F. Caputo¹

Structural Durability & Health Monitoring, Vol.2, No.1, pp. 51-68, 2006, DOI:10.3970/sdhm.2006.002.051

Abstract This work describes the results of the experience acquired by the authors during their participation to some among the European research programs with the aim to develop a probabilistic risk assessment procedure to analyse the spreading of fatigue-induced damage in typical aeronautical components. The several steps of the procedure are pointed out, and especially the modelling of the damage evolutionary process; the initiation and the transitional probabilities, which characterize the passage from one damage level to a higher one, are fully characterized and their dependence from time and from the damage state of surrounding zones More >

Luc Valiquette¹, Francesco Montorsi², Wayne J. G. Hellstrom³, Francois Giuliano⁴, Martin Homering⁵, Terry Taylor⁶, Ian Eardley⁷

Canadian Journal of Urology, Vol.12, No.3, pp. 2687-2698, 2005

Abstract Objective: To assess success rates in ability to penetrate (Sexual Encounter Profile question 2 [SEP2]) and maintain erections to completion of intercourse (SEP3) from time of dosing to start of sexual activity in a retrospective analysis of two pivotal trials.
Methods: In two randomized, double-blind studies, men with ED for >6 months received vardenafil 5 mg, 10 mg, or 20 mg or placebo for 12-26 weeks. Patients were instructed to start sexual activity 1 hour after dosing. In this retrospective pooled analysis, patient diary questions through week 12 were analyzed, providing attempt data was recorded 0-12 hours… More >

Walid Farhat, Gordon McLorie, Darius Bagli, Antoine Khoury

Canadian Journal of Urology, Vol.9, No.1, pp. 1459-1463, 2002

Abstract Purpose: Infants with history of antenatal hydronephrosis and neonatal vesicoureteral reflux may have detectable changes in renal scans before the advent of urinary tract infection. In cases of bilateral high-grade vesicoureteral reflux, differential renal function on renal scan may not reveal renal hypoplasia since comparison of relative function may be made between two abnormal kidneys. We tested the hypothesis that ultrasonography in the neonatal period may be accurate and complementary to renal scan in detecting renal hypoplasia at birth.
Materials and methods: Twenty-six infants who presented in the antenatal period with history of hydronephrosis and were noted… More >