(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

The performance (sensing/actuating) of a piezotransducer highly depends upon the ability of the bond layer to transfer the stress and strain (through shear lag mechanism) between the transducer and the structure. Therefore, the coupled electromechanical response of the piezotransducer should consider the effect of dynamic behaviour, geometry and composition of the adhesive layer used to bond the transducer patch on the structure. This article presents a new refined analytical model for inclusion of the shear lag effect in modelling of adhesively bonded piezoelectric ceramic (lead zirconate titanate) patches for consideration in the electromechanical impedance technique. The previous models neglected the inertial term in shear lag formulations for simplicity. The present refined model, on the other hand, considers the inertial and the shear lag effects simultaneously, and is therefore more rigorous and complete. In this article, the formulations are first derived for one-dimensional case, and then extended to two-dimensional lead zirconate titanate-structure interaction. The overall results are found to be in better proximity to experimental observations. The refined formulations are employed for a detailed stress analysis of the bond layer. The article concludes with a parametric study on the influence of various sensor parameters on the electromechanical impedance signatures. © The Author(s) 2012.

World University root node

Civil Engineering

Fulltext

Journal of Intelligent Material Systems and Structures

A refined shear lag model for adhesively bonded piezo-impedance transducers

Mobile Agent (MA) based computing paradigm offers many advantages over the existing and widely used client/server computing paradigm in wireless sensor networks (WSN). MA performs the task of data processing and data aggregation at the nodes rather than at the sink, thus, eliminating the redundancy in the sensory data. One of the most important issues in MA based paradigm is planning of an itinerary (route) for MA traversal. In this paper, we present a centralized MA itinerary planning approach using Analytic Hierarchy Process (AHP). The remaining energy of the node, migration cost and information gain are taken into consideration for the selection of subsequent node of the itinerary. AHP is used for determining the weights to each of the above parameter, thus, simplifying the task of decision making. Simulation results exhibit that the proposed approach lowers the task duration and energy consumption of the network. © 2013 IEEE.

Computer Science and Engineering

IMPACT 2013 - Proceedings of the International Conference on Multimedia Signal Processing and Communication Technologies

Mobile agent itinerary planning using analytic hierarchy process for wireless sensor networks

We report the synthesis, mesomorphic behavior, and mobility values of a series of highly ordered N-substituted triindole-based columnar liquid crystals. Shortening the length of N-alkylic substituents from N-dodecyl to N-methyl chains results in a drastic approach of the disks within the columns and in an impressive increase in charge carrier mobility. An study of aggregation in solution provide insights into the intermolecular forces responsible of the reduction of the intrastack distance as the size of the N-alkyl chains is decreased and offer evidence of stabilization of the columns by the contribution of cooperative CH-π interactions. The materials presented here exhibit mobility values, even in totally misaligned columnar phases, that may compete with those of the best polycrystalline organic semiconductors, without the need of costly vacuum evaporation processes. © 2012 American Chemical Society.

Electrical Engineering

Chemistry of Materials

High hole mobility in triindole-based columnar phases: Removing the bottleneck of homogeneous macroscopic orientation

Wireless sensor networks (WSN) MAC protocol has been the active research area since last few years because of application specific nature of these networks. This paper studies popular contention based SMAC protocol in multihop scenario and analyzes its suitability in mission critical WSN applications. Along with the residual energy, the throughput and packet delivery ratio are considered as the important parameters for mission critical applications. Improvements are suggested in the SMAC protocol with the simulation results in NS-2. © 2013 IEEE.

Proceedings of the 2013 3rd IEEE International Advance Computing Conference, IACC 2013

Analysis of SMAC protocol for missioon critical applications in wireless sensor networks

The increasing availability of Global Positioning System (GPS) enabled devices has given an opportunity for learning patterns of human behavior from the GPS traces. This paper describes how to extract popular and significant places (locations) by analyzing the GPS traces of multiple users. In contrast to the existing techniques, this approach takes into account the semantic aspects of the places in order to find interesting places in a geo-spatial region. GPS traces of multiple users are used for mining the places which are frequently visited by multiple users. However, the semantic meanings, such as 'historical monument', 'traffic signal', etc can further improve the ranking of popular places. The end result is the ranked list of popular places in a given geo-spatial region. This information can be useful for recommending interesting places to the tourists, planning locations for advertisement hoardings, traffic planning, etc. © 2013 Springer-Verlag Berlin Heidelberg.

Lecture Notes in Computer Science (including subseries Lecture Notes in Artificial Intelligence and Lecture Notes in Bioinformatics)

Mining Popular Places in a Geo-spatial Region Based on GPS Data Using Semantic Information

Aerosol acidity is one of the most important parameters that can influence atmospheric visibility, climate change and human health. Based on continuous field measurements of inorganic aerosol species and their thermodynamic modeling on a time resolution of 1h, this study has investigated the acidic properties of PM2.5 and their relation with the formation of secondary inorganic aerosols (SIA). The study was conducted by taking into account the prevailing ambient temperature (T) and relative humidity (RH) in a tropical urban atmosphere. The in-situ aerosol pH (pHIS) on a 12h basis ranged from -0.20 to 1.46 during daytime with an average value of 0.48 and 0.23 to 1.53 during nighttime with an average value of 0.72. These diurnal variations suggest that the daytime aerosol was more acidic than that caused by the nighttime aerosol. The hourly values of pHIS showed a reverse trend as compared to that of in-situ aerosol acidity ([H+]Ins). The pHIS had its maximum values at 3:00 and at 20:00 and its minimum during 11:00 to 12:00. Correlation analyses revealed that the molar concentration ratio of ammonium to sulfate (RN/S), equivalent concentration ratio of cations to anions (RC/A), T and RH can be used as independent variables for prediction of pHIS. A multi-linear regression model consisting of RN/S, RC/A, T and RH was developed to estimate aerosol pHIS.. © 2013 Elsevier B.V.

Science of the Total Environment

A study of diurnal variations of PM2.5 acidity and related chemical species using a new thermodynamic equilibrium model

This study has investigated the chemical association among acidic gases, ammonia and secondary inorganic aerosols based on hourly measurements in a tropical urban atmosphere. The 24 hr average concentrations of SO2, NH3, HONO, HNO3 and HCl were 21.77, 2.47, 1.73, 3.00 and 0.08 μg/m3, respectively while those of SO42-, NO3-, Cl-, Na+, K+, NH4+, Ca2+ and Mg2+ in PM2.5 were 4.41, 1.29, 0.28, 0.30, 0.32, 1.76, 0.14 and 0.07 μg/m3, respectively. The results of this study for SO2, NH3, HONO, HCl, SO42- and Cl- showed significant diurnal variations, whereas there was a lack of significant diurnal variations for HNO3, NO3-, Na+, NH4+, Ca2+ and Mg2+. Analysis of the charge balance of ionic species indicated that sufficient NH3 was present most of the time to neutralize both H2SO4 and HNO3 to form (NH4)2SO4 and NH4NO3. The conversion of SO2 into SO42- and HNO3 into NO3- was observed to be sensitive to changes in temperature and relative humidity, respectively. The study area experienced ambient relative humidity, which was higher than the estimated deliquescence relative humidity of NH4NO3 most of the time during the measurement period. As a result, the NH4NO3 formation was thermodynamically favorable during both daytime and nighttime. However, NH4Cl formation was not favored under ammonia-poor conditions. It was observed that biomass burning could trigger nitrate and chloride formation in the ambient air. © Taiwan Association for Aerosol Research.

Aerosol and Air Quality Research

Insights into chemical coupling among acidic gases, ammonia and secondary inorganic aerosols

The piezoelectric patches have started to play an important role in continuous online health monitoring of structures in recent years because of their diminutive shape, cost effectiveness and easy installation process. The research for structural identification and force transfer phenomena has recently become an area of interest researchers working in PZT related structural health monitoring. The PZT patch allow the systems and structures to monitor their own structural integrity while in operation and throughout their life, and are useful not only to improve reliability but also to reduce maintenance and inspection cost of systems and structures specifically, in the electro-mechanical impedance (EMI) technique based SHM, the PZT patches are either embedded or bonded with adhesive to the host structure to be monitored. When bonded on the surface of the structure, the adhesive bond forms an interfacial layer of finite thickness between the patch and host structure. The performance (sensing/actuating) of piezo transducer depends upon the ability of the bond layer to transfer the stresses and strains between the active PZT patch and the host structures. The mechanical and geometrical properties of the adhesive bond layer change the overall performance of the PZT-structure interaction model. The main objective of this paper to review the shear lags models developed so far and discuss their effective applicability EMI technique.

Structural Health Monitoring 2013: A Roadmap to Intelligent Structures - Proceedings of the 9th International Workshop on Structural Health Monitoring, IWSHM 2013

Investigation of shear force mechanism in electro-mechanical impedance (EMI) technique for structural health monitoring

Size-tunable polymeric nanoparticles have been successfully produced by a microfluidic-assisted nanoprecipitation process. A multilamination micromixer has been chosen to fabricate continuously nanoparticles of methacrylic polymers. Various operating conditions, such as the polymer concentration, the amount of non-solvent and the characteristics of the raw polymer (molecular weight and architecture: linear vs. branched) have been investigated. Their influences on the final particle size, ranging from 76 to 217 nm, have been correlated to the mechanisms leading to the formation of nanoparticles. In this type of microfluidic device, mixing mainly operates by diffusion mass transfer, helped by hydrodynamic focusing. The effect of micromixing on the size of particles has also been shown experimentally and supported by a computational fluid dynamics (CFD) study. A mixing criterion has been defined and numerically calculated to corroborate the effect of the flow rate of polymer solution on the particles size. An increase in the polymer solution flow rate increases the value of this mixing criterion, resulting in smaller nanoparticles. © 2012 Elsevier Ltd. All rights reserved.

Chemical Engineering

Polymer

Improved size-tunable preparation of polymeric nanoparticles by microfluidic nanoprecipitation

Introduction: The kinetics of the transformation of ammonia and acid gases into components of PM2.5 has been examined. The interactions of existing aerosols and meteorology with the transformation mechanism have also been investigated. The specific objective was to discern the kinetics for the gas-to-particle conversion processes where the reactions of NH3 with H2SO4, HNO3, and HCl take place to form (NH4)2SO4, NH4NO3, and NH4Cl, respectively, in PM2.5. Materials and methods: A Teflon-based outdoor environmental chamber facility (volume of 12.5 m3) with state-of-the-art instrumentation to monitor the concentration-time profiles of precursor gases, ozone, and aerosol and meteorological parameters was built to simulate photochemical reactions. Results and discussion: The reaction rate constants of NH3 with H2SO4, HNO3, and HCl (i. e., kS, kN, and kCl) were estimated as (1) kS = 2.68 × 10-4 (±1.38 × 10-4) m3/μmol/s, (2) kN = 1.59 × 10-4 (±8. 97 × 10-5) m3/μmol/s, and (3) kCl = 5.16 × 10-5 (±3.50 × 10-5) m3/μmol/s. The rate constants kS and kN showed significant day-night variations, whereas kCl did not show any significant variation. The D/N (i. e., daytime/nighttime values) ratio was 1.3 for kS and 0.33 for kN. The significant role of temperature, solar radiation, and O3 concentration in the formation of (NH4)2SO4 was recognized from the correlation analysis of kS with these factors. The negative correlations of temperature with kN and kCl indicate that the reactions for the formation of NH4NO3 and NH4Cl seem to be reversible under higher temperature due to their semivolatile nature. It was observed that the rate constants (kS, kN, and kCl) showed a positive correlation with the initial PM2.5 levels in the chamber, suggesting that the existing surface of the aerosol could play a significant role in the formation of (NH4)2SO4, NH4NO3, and NH4Cl. Conclusions: Therefore, this study recommends an intelligent control of primary aerosols and precursor gases (NOx, SO2, and NH3) for achieving reduction in PM2.5 levels. © 2011 Springer-Verlag.