(SoE) School of Engineering

<p>Shiv Nadar University is a comprehensive, multidisciplinary, research-focused, and student-centric University offering a full range of academic programs at the undergraduate, postgraduate and doctoral level. With state-of-the-art infrastructure, the University comprises of academic wings, sophisticated labs, international standard sports facilities, amphitheaters, auditorium, conference rooms and smart classrooms. The University&rsquo;s goal is to become internationally recognized for the quality of its research and creative endeavors and their applicability to improving quality of life, generating new insights and expanding the boundaries of human knowledge creativity. Committed to excellence in teaching, research and service, the University aims to serve the higher education needs of India and the world beyond.</p>

Shiv Nadar University

In the present communication, comparison between performance of photovoltaic module with and without duct has been carried out. Different input parameters (namely, ambient air temperature, solar radiation wind speed etc.) have been considered for HT, Delhi campus. Further, thermal modelling has been derived for the c-Si photovoltaic (PV) module alone and PV module with duct. Different parameters like outlet air temperature from duct and cell temperature have been calculated through MATLAB coding. Due to integration of duct, 3.89\% and 125.74\% increase in electrical output and equivalent thermal energy have been found in comparison to stand-alone PV module. © 2019 Elsevier Ltd. All rights reserved.

Mechanical Engineering

World University root node

Materials Today: Proceedings

Study to improve the efficiency of c-Si material in photovoltaic power plant

In the present investigation, various efficiencies and productivity of N identical partially covered PVT flat plate collectors integrated single slope solar distiller unit have been computed at different water depth under optimized condition to see the effect of variation of water depth on hourly and daily efficiencies and productivity. The meteorological data of 2 months: one belonging to winter season say January and the other belonging to summer season say June have been considered for New Delhi climatic condition. The hourly and daily thermal efficiencies, hourly and daily exergy efficiencies, hourly and daily electrical efficiencies, hourly and daily overall exergy efficiencies and hourly and daily productivities have been evaluated under optimized condition. It has been concluded that the increase in values of average daily efficiencies and productivity is significant till 1.4 m water depth. © 2019 Desalination Publications. All rights reserved.

Desalination and Water Treatment

Effect of depth of water on various efficiencies and productivity of N identical partially covered PVT collectors incorporated single slope solar distiller unit

In a coherent time-varying MIMO multiple access channel (MAC), the ergodic sum-capacity can be achieved by suitable power control, which adapts the transmit covariance matrices based on the available channel state information (CSI). We consider a MIMO-MAC model where each transmitter is only aware of its own fading realization. For this distributed MAC, we propose decentralized power control schemes. First, some key structural properties on the optimal power control laws are derived, followed by an upper bound on the sum-capacity. Numerical results show that the proposed power control schemes closely characterize the sum-capacity in several regimes of interest.

Electrical Engineering

IEEE International Symposium on Information Theory - Proceedings

On Decentralized Power Control for Ergodic MIMO Multiple Access Channels

This work aims to collect and analyze air quality information in and around regions of Delhi using an IoT system which is placed in a moving vehicle. Hourly air quality data has been used to forecast exceedance probabilities and return periods for air pollution extremes. The exceedance probabilities and return periods obtained using Extreme Value Distribution (EVD) have been compared to actual occurrences of extreme events.The results indicate that the EVD based air quality model is best suited for forecasting air quality in this high pollutant concentration region. © 2019 IEEE.

Computer Science and Engineering

SAS 2019 - 2019 IEEE Sensors Applications Symposium, Conference Proceedings

IoT System based Forecasting and Modeling Exceedance Probability and Return Period of Air Quality using Extreme Value Distribution

Interaction of fluid forces with flexible structures is often prone to dynamical instabilities, such as aeroelastic flutter. The onset of this instability is marked by sustained large amplitude oscillations and is detrimental to the structure's integrity. Therefore, investigating the possible physical mechanisms behind the onset of flutter instability has attracted considerable attention within the aeroelastic community. Recent studies have shown that in the presence of oncoming fluctuating flows, the onset of flutter instability is presaged by an intermediate regime of oscillations called intermittency. Further, based on the intensity of flow fluctuations and the relative time scales present in the flow, qualitatively different types of intermittency at different flow regimes have been reported hitherto. However, the coupled interaction between the pitch (torsion) and plunge (bending) modes during the transition to aeroelastic flutter has not been explored. With this, we demonstrate with a mathematical model that the onset of flutter instability under randomly fluctuating flows occurs via a mutual phase synchronization between the pitch and the plunge modes. We show that at very low values of mean flow speeds, the response is by and large noisy and, consequently, a phase asynchrony between the modes is present. Interestingly, during the regime of intermittency, we observe the coexistence of patches of synchronized periodic bursts interspersed amidst a state of desynchrony between the pitch and the plunge modes. On the other hand, at the onset of flutter, we observe a complete phase synchronization between the pitch and plunge modes. This study concludes by utilizing phase locking value as a quantitative measure to demarcate different states of synchronization in the aeroelastic response. © 2019 Author(s).

Fulltext

Chaos

Synchronization of pitch and plunge motions during intermittency route to aeroelastic flutter

Superhydrophobic textured surfaces are known to maintain a nonwetted state unless external stimuli are applied since they can withstand high wetting pressure. Herein, we report a new category of tunable, one-dimensional (1D) Cassie-to-Wenzel wetting transitions during evaporation, even on superhydrophobic surfaces. The transition initiates at the periphery of the evaporating drop, and the wetting transition propagates toward the center of the drop. The transitions are observed for surfaces with wetting pressures as high as ~ 7,568 Pa, which is much higher than the Laplace pressure, i.e., ~200 Pa. In situ high-contrast fluorescence microscopy images of the evaporating drop show that the transition is induced by preferential depinning of the air-water interface and subsequent formation of air bubbles in the cavities near the three-phase contact line. The evaporation-induced internal flow enhances the pressure within the water droplet and subsequently causes a Cassie-to-Wenzel wetting transition. © 2019, © 2019 Taylor & Francis.

Nanoscale and Microscale Thermophysical Engineering

Internal-Flow-Mediated, Tunable One-dimensional Cassie-to-Wenzel Wetting Transition on Superhydrophobic Microcavity Surfaces during Evaporation

Thermal spray coatings are widely used for addressing erosion problems in fluid machineries. However, the presence of splat boundaries, non-homogeneous microstructure and element segregation limits their performance. In this study, we developed Ni-Cr-40Al2O3 coatings on stainless steel (SS316L) substrate using high-velocity flame spray followed by post-processing using friction stir processing. The performance of as-sprayed and processed coatings was evaluated in slurry erosion, erosion–corrosion and pure corrosion in 3.5\% NaCl solution. As-sprayed coating showed lower erosion and erosion–corrosion resistance compared to stainless steel. Friction stir processing resulted in significant microstructure refinement concurrent with enhanced hardness and fracture toughness of the developed coating. At oblique impingement angle, the processed coating showed nearly 30\% to twofold higher erosion and erosion–corrosion resistance compared to stainless steel substrate. During pure erosion at normal impingement, both as-sprayed and processed coating showed higher volume loss. However, during erosion–corrosion at normal impingement, the processed coating was able to demonstrate similar volume loss as that of the substrate. In addition, the processed coating showed significant improvement in the corrosion performance as well. The study showed that friction stir processing could be a promising pathway to unravel the deleterious effects of inherent non-homogeneities in thermal spray coatings. © 2019, ASM International.

Journal of Thermal Spray Technology

Post-processing of Ni-Cr-Al2O3 Thermal Spray Coatings Through Friction Stir Processing for Enhanced Erosion–Corrosion Performance

Amorphous metals, also known as bulk metallic glasses, are promising materials for advanced healthcare applications. This is attributed to their exceptional properties, unseen in crystalline materials. Their unique ability to undergo relaxation during low temperature annealing provides opportunity to develop tailored properties. Here, we show a new pathway to significantly accelerate the relaxation kinetics in a zirconium based metallic glass through severe surface deformation using thermo-mechanical processing. The combined strain and thermal field during thermo-mechanical processing significantly reduced the relaxation time compared to vacuum annealing concurrent with remarkable enhancement in its bio-corrosion resistance. The corrosion resistance was found to have a direct correlation with the wetting behavior and oxide layer composition. The surface of relaxed glass was found to be rich in zirconium oxide compared to its as-cast state with higher fraction of aluminum oxide. The difference in oxide layer composition was attributed to annihilation of free volume in relaxed glass resulting in limited atomic transport. Relaxed metallic glass exhibited more hydrophobic nature likely due to its lower surface energy state as a consequence of structural densification. In addition, the relaxed glass showed better cell proliferation, thereby, enhancing its appeal as a next-generation biomaterial. © 2019 Elsevier B.V.

Applied Surface Science

Enhancement in bio-corrosion resistance of metallic glass by severe surface deformation

The dispersion equation of a dielectric loaded anisotropically conducting tape helix slow wave structure for planar TWTs is derived. By assuming the current density behavior on the rectangular tape helix, the dispersion relation is obtained through accurate boundary conditions that restrict the field only on the tape surface and not in the gap regions. Substitution of the field equations in the boundary conditions results in the six complex constants of the field equations. The complex constants are re-substituted in the last boundary condition that consists of the restricting function or the indicator function to arrive at the dispersion equation. The derived dispersion equation can be used to obtain the dispersion characteristics for a more practically relevant planar TWT interaction structure. © 2019 IEEE.

2019 6th International Conference on Signal Processing and Integrated Networks, SPIN 2019

Analysis of Dielectric Rods Supported Anistropically Conducting Rectangular Helix Slow Wave Structure

Borondipyrromethene or BODIPY can be incorporated into the polymer backbone through either the α (or 2,6) positions or the β (3,5) positions and hence resulting in polymers exhibiting structural isomerism. In this work two pairs of such isomeric D-A polymers formed by copolymerization of BODIPY with benzodithiophene (P1 and P2) and fluorene (P3 and P4) separately are reported along with structure property correlation. Depending on the positions of attachment of the BODIPY unit in the isomeric polymers, the geometry of the polymer backbone is either coiled or linear which in turn affects physical properties such as thermal stability, solubility and absorption, electronic properties such as delocalization of molecular orbitals, HOMO-LUMO energy levels and band gap. Though the charge carrier mobility seems to remain unaffected due to the isomerism of the polymer backbone, the α connected polymers perform better than the β connected polymers when used as electron acceptor along with P3HT in all polymer solar cells. This is also the first instance of application of BODIPY copolymers as electron acceptor in organic solar cells. © 2019 International Solar Energy Society