Residual factor as a variable in slope reliability analysis

Bulletin of Engineering Geology and the Environment - In the past, residual factor R in strain-softening soil slopes has been included, either directly or indirectly, as a deterministic variable in...     

Exploring a reversible NOR from a 4 × 4 modified Fredkin gate and its optical mapping using a LiNbO3-based MZI

Journal of Computational Electronics - The extensive search for the implementation of reversible logic using emerging technologies has paved the way for the rise of optical computing. The...     

Effects of atmospheric weather and turbulence in MSK based FSO communication system for last mile users

Telecommunication Systems - In this paper, a minimum shift keying (MSK) based free space optical (FSO) communication system for the terrestrial user is modeled. In our setup 10 Gbps...     

Efficient computational system reliability analysis of reinforced soil-retaining structures under seismic conditions including the effect of simulated noise

This article presents a computational reliability analysis of reinforced soil-retaining structures (RSRS) under seismic conditions. The internal stability of RSRS is evaluated using the horizontal slice method (HSM) with modified pseudo-dynamic seismic forces. Two different failure modes of RSRS are identified and their reliability indices are computed using the first-order reliability method (FORM). The critical probabilistic failure surface is identified using a three-tier optimization scheme. Reliability index of the system is computed by considering the modes of failure to be connected in series. The tension mode is found to be the most critical mode of failure. The present study identifies that the wall height (H), shear wave velocity of the soil (V_s), and predominant frequency of the input motion (ω) govern the response of RSRS. Reliability indices depend on a parameter termed as the normalized frequency (ωH/V_s) and their values decrease with an increase in the value of ωH/V_s. Increase in the damping ratio of soil, increases the value of reliability indices, especially for ωH/V_s values, which are close to π/2. The FORM suffers from few critical shortcomings such as linear assumption of limit state surface at the most probable point of failure and its ability to consider only the statistical uncertainties excluding the effect of epistemic uncertainties. This calls for sampling-based numerical techniques such as Monte-Carlo simulation (MCS) which gives more comprehensive understanding of the problem under consideration in a probabilistic framework. Thus, a computationally efficient surrogate-assisted MCS is carried out to validate the present formulation and provide numerical insights by capturing the system dynamics over the entire design domain. Adoption of the efficient surrogate-assisted approach allowed us to quantify the epistemic uncertainty associated with the system using Gaussian white noise (GWN). Subsequently, its effects on the system reliability index and probabilistic behavior of the critical parameters are presented. The numerical results clearly indicate that it is imperative to take into account the probabilistic deviations of the critical performance parameters for RSRS to ensure adequate safety and serviceability under operational condition while quantifying the reliability of such systems.

     

Development of a Non-collinear Nonlinear Ultrasonic-Based Technique for the Assessment of Crack Tip Deformation

Non-collinear nonlinear ultrasonic (NCNLU) wave mixing technique has been established to study the localized plastic deformation at the crack tip during fatigue. A pair of ultrasonic shear wave was mixed non-collinearly to obtain a longitudinal wave of frequency equal to the sum of the two shear wave frequencies under a resonant condition. Experiments were carried out on notched 9Cr-1Mo 3-point bend specimen during high-cycle fatigue. The variation of the NCNLU parameter with the stress accumulation at the crack tip during the fatigue crack initiation and propagation and mapping of the deformation zone around the crack tip are described in this paper.     

Higher harmonic analysis of ultrasonic signal for ageing behaviour study of C-250 grade maraging steel

Higher order harmonic analysis of ultrasonic signal has been applied to study the precipitation kinetics of 18Ni maraging steel. The material has been solution annealed (SA) at a temperature of 1088 K for 1 h and then air quenched. Ageing of SA materials have been done at 728 K for different durations of 10 min to 100 h and air cooled. It has been found that the measurement parameter of this new technique increases with the formation of finer precipitates at the initial stage of ageing till 12 h and then decreases at longer holding time with the coarsening of precipitates.