Prediction of the aerodynamic behavior of a rounded corner square cylinder at zero incidence using ANN

AbstractThe aerodynamic behavior of a square cylinder with rounded corner edges in steady flow regime in the range of Reynolds number (Re) 5–45; is predicted by Artificial Neural Network (ANN) using MATLAB. The ANN has trained by back propagation algorithm. The ANN requires input and output data to train the network, which is obtained from the commercial Computational Fluid Dynamics (CFD) software FLUENT in the present study. In FLUENT, all the governing equations are discretized by the finite volume method. Results from numerical simulation and back propagation based ANN have been compared. It has been discovered that the ANN predicts the aerodynamic behavior correctly within the given range of the training data. It is additionally observed that back propagation based ANN is an effective tool to forecast the aerodynamic behavior than simulation, that has very much longer computational time

Numerical Analysis and Prediction of Unsteady Forced Convection over a Sharp and Rounded Edged Square Cylinder

An unsteady two-dimensional forced convection over a square cylinder with sharp and rounded corner edge is numerically analyzed for the low Reynolds number laminar flow regime. In this study, the analysis is carried out for Reynolds number (Re) in the range of 80 to 180 with Prandtl number (Pr) variation from 0.01 to 1000 for various corner radius (r=0.50, 0.51, 0.54, 0.59, 0.64 and 0.71). The lateral sides of the computational domain are kept constant to maintain the blockage as 5%. Heat transfer due to unsteady forced convection has been predicted by Artificial Neural network (ANN). The present ANN is trained by the input and output data which has been acquired from the numerical simulation, performed in finite volume based Computational Fluid Dynamics (CFD) commercial software FLUENT. The heat transfer characteristics over the sharp and rounded corner square cylinder are evaluated by analyzing the local Nusselt number (Nulocal), average Nusselt number (Nuavg) at various Reynolds number, Prandtl numbers and for various corner radii. It is found that the heat transfer rate of a circular cylinder can be enhanced by 12% when Re is varying and 14% when Prandtl number is varying by introducing a new cylinder geometry of corner radius r=0.51. It is found that the unsteady forced convection heat transfer over a cylinder can be predicted appropriately by ANN. It is also observed that the back propagation ANN can predict the heat transfer characteristics of forced convection very quickly compared to a standard CFD method

A Two-year Outcome of Various Techniques of Discectomy On Complications: A Multicentric Retrospective Study

Objective Various techniques of performing lumbar discectomy are prevalent, each having its rationale and claimed benefits. The authors ventured to assess the total complication rate of lumbar discectomy as well as the complication rates of individual complications, namely CSF leaks, superficial wound infections, deep wound infections, recurrence rates, re-operation rates, and wrong level surgery. Methods This was a retrospective study of patients operated using open discectomy (OD), microdiscectomy (MD), microendoscopic discectomy (MED), interlaminar endoscopic lumbar discectomy (IELD), transforaminal endoscopic lumbar discectomy (TELD), and Destandau techniques (DT) with a minimum follow-up of 2 years. The inclusion criteria were age>15 years, failed conservative treatment for 4-6 weeks, and the involvement of a single lumbar level. Results There is no statistically significant association between surgical technique and complications. The total complication rate was 12.89% in 946 operated cases. The most common complication was recurrence (5.81%), followed by re-operation (3.69%), CSF leak (1.90%), wrong level surgery (0.63%), superficial infection (0.52%) and deep infection (0.31%). There were minor differences in the incidence of complications between techniques. Conclusion This is the first study to compare the complication rates of all the prevalent discectomy techniques across the globe in 946 patients. Although there were minor differences in incidences of complications between individual techniques, there was no statistical significance. The various rates of individual complications provide a reference value for future studies related to complications following discectomy

Nanocolumnar Crystalline Vanadium Oxide-Molybdenum Oxide Antireflective Smart Thin Films with Superior Nanomechanical Properties

Vanadium oxide-molybdenum oxide (VO-MO) thin (21-475 nm) films were grown on quartz and silicon substrates by pulsed RF magnetron sputtering technique by altering the RF power from 100 to 600 W. Crystalline VO-MO thin films showed the mixed phases of vanadium oxides e.g., V2O5, V2O3 and VO2 along with MoO3. Reversible or smart transition was found to occur just above the room temperature i.e., at similar to 45-50 degrees C. The VO-MO films deposited on quartz showed a gradual decrease in transmittance with increase in film thickness. But, the VO-MO films on silicon exhibited reflectance that was significantly lower than that of the substrate. Further, the effect of low temperature (i.e., 100 degrees C) vacuum (10(-5) mbar) annealing on optical properties e.g., solar absorptance, transmittance and reflectance as well as the optical constants e.g., optical band gap, refractive index and extinction coefficient were studied. Sheet resistance, oxidation state and nanomechanical properties e.g., nanohardness and elastic modulus of the VO-MO thin films were also investigated in as-deposited condition as well as after the vacuum annealing treatment. Finally, the combination of the nanoindentation technique and the finite element modeling (FEM) was employed to investigate yield stress and von Mises stress distribution of the VO-MO thin films

Application of Multivariate Adaptive Regression Spline-Assisted Objective Function on Optimization of Heat Transfer Rate Around a Cylinder

The present study aims to predict the heat transfer characteristics around a square cylinder with different corner radii using multivariate adaptive regression splines (MARS). Further, the MARS-generated objective function is optimized by particle swarm optimization. The data for the prediction are taken from the recently published article by the present authors [P. Dey, A. Sarkar, A.K. Das, Development of GEP and ANN model to predict the unsteady forced convection over a cylinder, Neural Comput. Appl. (2015) 1–13]. Further, the MARS model is compared with artificial neural network and gene expression programming. It has been found that the MARS model is very efficient in predicting the heat transfer characteristics. It has also been found that MARS is more efficient than artificial neural network and gene expression programming in predicting the forced convection data, and also particle swarm optimization can efficiently optimize the heat transfer rate

Acoustic Beamforming : Design and Development of Steered Response Power With Phase Transformation (SRP-PHAT).

Acoustic Sound Source localization using signal processing is required in order to estimate the direction from where a particular acoustic source signal is coming and it is also important in order to find a soluation for hands free communication. Video conferencing, hand free communications are different applications requiring acoustic sound source localization. This applications need a robust algorithm which can reliably localize and position the acoustic sound sources. The Steered Response Power Phase Transform (SRP-PHAT) is an important and roubst algorithm to localilze acoustic sound sources. However, the algorithm has a high computational complexity thus making the algorithm unsuitable for real time applications. This thesis focuses on describe the implementation of the SRP-PHAT algorithm as a function of source type, reverberation levels and ambient noise. The main objective of this thesis is to present different approaches of the SRP-PHAT to verify the algorithm in terms of acoustic enviroment, microphone array configuration, acoustic source position and levels of reverberation and noise

Acoustic Beamforming : Design and Development of Steered Response Power With Phase Transformation (SRP-PHAT).

Acoustic Sound Source localization using signal processing is required in order to estimate the direction from where a particular acoustic source signal is coming and it is also important in order to find a soluation for hands free communication. Video conferencing, hand free communications are different applications requiring acoustic sound source localization. This applications need a robust algorithm which can reliably localize and position the acoustic sound sources. The Steered Response Power Phase Transform (SRP-PHAT) is an important and roubst algorithm to localilze acoustic sound sources. However, the algorithm has a high computational complexity thus making the algorithm unsuitable for real time applications. This thesis focuses on describe the implementation of the SRP-PHAT algorithm as a function of source type, reverberation levels and ambient noise. The main objective of this thesis is to present different approaches of the SRP-PHAT to verify the algorithm in terms of acoustic enviroment, microphone array configuration, acoustic source position and levels of reverberation and noise

Steady flow over triangular extended solid attached to square cylinder – A method to reduce drag

Numerical analysis of two dimensional steady flows over a triangular extended solid (thorn) attached to square cylinder positioned at front stagnation point and at rear stagnation point separately is reported at low Reynolds number (Re = 40). The variation of thorn length (l′ = 0.2, 0.4 & 0.6) & inclination angle (Θ = 5°, 10°, 15° & 20°) and its effect on the drag, pressure, shear stress, boundary layer as well as on the inertia force and viscous force are of interest. There is comparatively large variation on drag when the thorn is placed at the front side instead of placing at rear. The recirculation length is remained constant by varying the length and inclination of the thorn irrespective of its position. The variation of drag is comparatively less by changing thorn inclination. It is found that the drag is minimized by 2–3% compared to square model

Numerical analysis of drag and lift reduction of square cylinder

AbstractFlow around an extended triangular solid (thorn) attached to a square cylinder is investigated numerically. The numerical analysis is carried out at low Reynolds number, Re = 100 & 180 for different non-dimensional thorn lengths (l΄ = 0. 2, 0.4 & 0.6), different inclination angles (θ = 5°, 10°, 15° and 20°) and two different thorn positions. It is found that drag and lift reduction can be achieved by attaching the thorn on a square cylinder. It is observed that the fluctuation of the drag force as well as the lift force is reduced and there is a comparatively large variation of drag and lift when the thorn is placed at the front stagnation point instead of placing at rear stagnation point. The reduction of drag and lift coefficient are directly proportional to thorn length and thorn inclination angle. It is found that the drag and lift are minimized by 16% & 46% for Re = 100 respectively, and 22% & 60% for Re = 180 compared to a square model (without thorn)