Vignan University

About: Vignan University is a education organization based out in Guntur, Andhra Pradesh, India. It is known for research contribution in the topics: Computer science & Control theory. The organization has 1138 authors who have published 1381 publications receiving 7798 citations.

Statistical analysis for fatigue life evaluation of woven E-glass/epoxy composite laminates containing off-centre interacting circular holes

Abstract: Fatigue behaviour of woven E-glass/epoxy composite laminates containing off-centre interacting circular holes was determined under sinusoidal loading in tension–tension at 0.1 stress ratio. Laminate samples with central hole were also investigated. Tensile and fatigue tests were conducted on specimens in load control mode. For the unnotched, central holed and off-centre interacting holed laminates, fatigue life was evaluated using a two-parameter Weibull distribution function at different probabilities and confidence levels. Results indicated that the number of samples taken at each stress level of fatigue experiments is adequate for the S–N curve generation at 90% confidence level and 90% Weibull probability. From the traditional and mean S–N curves, the effect of scatter on fatigue strengths of the specimens was investigated. Life distribution graphs were constructed to determine the fatigue life at any survival per cent. Damage forms and the associated causes were also explained.

A highly efficient precatalytic system (XPhos-PdG2) for the Suzuki-Miyaura cross-coupling of 7-chloro-1H-pyrrolo[2,3-c]pyridine employing low catalyst loading.

Abstract: An expedient catalytic method for the synthesis of diverse 7-(hetero) aryl-1H-pyrrolo[2,3-c]pyridine analogues via microwave-assisted Suzuki–Miyaura cross-coupling reaction with excellent yield was developed. The method is found to be compatible with various boronic acids and potassium organotrifluoroborates. The formation of highly stable monoligated catalytic species is found to be instrumental in driving the reactions to excellent conversions in Suzuki–Miyaura coupling. Herein, we report our findings on the use of a highly efficient precatalytic system (XPhos-PdG2), containing a bulky monodentate biaryl ligand which allows the rapid reductive elimination to form the true monoligated Pd(0) catalytic species, thereby facilitating the Suzuki coupling reaction of 7-chloro, 6-azaindole system containing unprotected free N–H group with excellent conversions employing low catalyst loadings. Also, we observed that the use of near stoichiometric potassium organotrifluoroborate reagents as alternative coupling partners for boronic acids, which are prone to protodeboronation, resulted in excellent conversions.

Hybridizing ant lion with whale optimization algorithm for compressed sensing MR image reconstruction via l 1 minimization: an ALWOA strategy

Abstract: In the field of image compression, the compressed sensing image reconstruction has made great achievements due to proper use of the image sparsity without the Nyquist sampling law constraint. For image information distribution, great deals of researches indicate that there exists obvious structural and statistical prior’s regularity and by the traditional compression algorithm it is difficult to achieve. In this paper, we propose a compressed sensing image reconstruction algorithm based on hybrid ALWOA strategy, which combines the ant lion optimization algorithm and the whale optimization algorithm. The hybrid algorithm produces a global search with faster convergence. By continuously learning the proposed hybrid method can find optimal solutions. The objective function for the image reconstruction process is taken as the l1 minimization problem. The reconstructed image is obtained by solving the l1 minimization problem. Extensive simulations have been conducted and the results show that the proposed method has achieved better performance when compared with traditional reconstruction algorithms.