(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

Least squares twin support vector machines (LSTSVM) [1] is a popular kernel-based SVM formulation for binary classification tasks. LSTSVM is an efficient algorithm to learn linear/nonlinear classification boundaries as it just requires solution of two linear systems of equations. LSTSVM has been applied to text categorization with simple bag-of-words representation and conventional feature selection. The disadvantage of this approach is that it is likely to hurt the classification performance due to loss of information as the features that are ranked lowest are discarded. However, as LSTSVM training involves solving for linear systems of equations of the size of input space dimension it is extremely important to keep the input dimension small and hence all features cannot be considered for training. Thus there is a need to learn a dense concept that combines many features without throwing them and produces a compact representation. Distributional clustering of words is an efficient alternative to traditional feature selection measures. Unlike feature selection measures which discard low ranked features, it generates extremely compact representation for text documents in word cluster space. It has been shown that SVM's classification performance is better/on par when using this new representation compared to traditional bag-of-words despite the advantages of reduced dimensionality of text documents. In this paper, we propose a new text categorization system combining distribution clustering of words for document representation and linear LSTSVM for document classification. We verified its effectiveness by conducting experiments on two benchmark text corpuses: WebKB, SRAA and comparing its results with SVMlight based classification in a similar setting. © 2015 IEEE.

World University root node

Electrical Engineering

Proceedings of the 2015 39th National Systems Conference, NSC 2015

Least squares twin support vector machines for text categorization

It is mandatory to keep total harmonic distortion in output of most inverters below a prescribed limit. The harmonic distortions caused due to non-linear loads may not get corrected by simple PID controllers. Repetitive controllers are more effective in such situations. Often repetitive controllers are used as add-on block to the conventional PID controller. Design of repetitive controller can be easily implemented on digital platform. Some controller parameters may have to be decided on trial and error basis. © 2015 IEEE.

Application of repetitive control for removal of harmonic distortions from inverter output

This paper presents the design of a Memristor based startup circuit for self biased circuits. Memristor has many advantages over conventional CMOS devices such as low leakage current at nanometer scale, easy to manufacture. In this work the switching characteristics of memristor is utilized. First the theoretical equations describing the switching behavior of memristor are investigated. To prove the switching capability of Memristor, a startup circuit based on memristor is proposed which uses series combination of Memristor and capacitor. Proposed circuit is compared with the previously reported MOSFET based startup circuits. Comparison of different circuits was done to validate the results. Simulation results show that memristor based circuit can attain on (I = 12.94 μA) to off state (I = 1.2 μA) in 25 ns while the MOSFET based startup circuits take on (I = 14.19 μA) to off state (I = 1.4 μA) in more than 90 ns. The benefit comes in terms of area because the number of components used in the circuit are lesser than the conventional startup circuits. © 2016 Author(s).

AIP Conference Proceedings

Memristor based startup circuit for self biased circuits

Nanoscale patterns have dimensions that are comparable to the length scales affected by intermolecular and surface forces. In this study, we systematically investigated the individual roles of curvature, surface energy, lateral stiffness, material, and pattern density in the adhesion and friction of nanopatterns. We fabricated cylindrical and mushroom-shaped polymer pattern geometries containing flat- and round-topped morphologies using capillary force lithography and nanodrawing techniques. We showed that the curvature, surface energy, and density of the patterns predominantly influenced the adhesive interactions, whereas lateral stiffness dominated friction by controlling the geometrical interaction between the indenter and pillar during sliding. Interestingly, in contrast to previous studies, cylindrical and mushroom-shaped pillars showed similar adhesion characteristics but very different frictional properties. Using fracture mechanics analysis, we showed that this phenomenon is due to a larger ratio of the mushroom flange thickness (t) to the radius of the pillar stem and we proposed a design criterion for mushroom patterns to exhibit a geckolike effect. The most important result of our work is the discovery of a linear master curve in the graph of adhesion versus friction for pillars with similar lateral stiffness values that is independent of curvature, material, surface energy, and pattern density. These results will aid in the identification of simple pattern parameters that can be scaled to tune adhesion and friction and will help broaden the understanding of nanoscale topographical interactions. © 2016 American Chemical Society.

Mechanical Engineering

ACS Applied Materials and Interfaces

Individual Role of the Physicochemical Characteristics of Nanopatterns on Tribological Surfaces

Variable frequency drive of single-phase induction motor can have many potential advantages, like reduced inrush current during starting, high starting torque, possibility of higher efficiency, more tolerant to variation in grid supply voltage etc. Many of the existing electrical gadgets use single-phase induction motor of capacitor start / capacitor-run type. A typical example is the motor used in household refrigerators. In this application the starting torque requirement is high. It will be good if the motor starts with reduced inrush current and if the amount of cooling by refrigerator is controlled by variable speed operation of the motor. This work proposes a power electronic circuit which can be incorporated with some change in the existing wiring circuit of the refrigerator. © 2015 IEEE.

2015 IEEE International WIE Conference on Electrical and Computer Engineering, WIECON-ECE 2015

Design and implementation of a variable frequency drive for single-phase induction motor

Research on developing the applications of Wireless Power Transfer System (WPTS) has increased considerably during last few years. Due to functional and environmental benefits, charging of electric vehicles via WPTS has been contemplated in academic and industrial research. The WPTS based on Magnetic Resonant Coupling Technique (MRCT) is considered as an efficient way for contactless power transfer over medium distances (up to about 20 to 30 centimeters). This paper presents a comprehensive MATLAB/SIMULINK based model for such a system. The parameters of the model are derived from mathematical equations presented in the paper. The performance of the model is also verified experimentally. Performance parameters, like power transfer efficiency and loss factor have been shown. © 2015 IEEE.

Comprehensive mathematical modelling and experimental analysis of a wireless power transfer system for neighborhood electric vehicles

In this paper, the design and fabrication of photovoltaic thermal integrated greenhouse system (PVTIGS) for biogas heating has been done for climatic condition of IIT Delhi, India. PVTIGS can also be used for a number of applications like generating electricity, space heating, enhancing production of biogas, crop cultivation and crop drying, etc. Thermal modelling of proposed system (PVTIGS) without load has been developed based on energy balance equations. Further, with the help of thermal modelling the solar cell temperature, room temperature and solar cell efficiency have been calculated for a typical clear day of May. Experimental validation have been done on the basis of correlation coefficient (r) and root mean square percentage deviation (e) and found to be in fair agreement between theoretical and experimental values. Effect of packing factor, mass flow rate of air below module, absorptivity (degradation effect) and transmittivity (dusting effect) on thermal load levelling have been discussed. Electrical energy has been calculated and validated with experimental values. Further, thermal energy and overall thermal energy have been evaluated and found to be 11.18 kW h and 12.76 kW h respectively for a clear day without load. © 2016 Elsevier Ltd

Solar Energy

Thermal modelling of photovoltaic thermal (PVT) integrated greenhouse system for biogas heating

A hybrid photovoltaic-thermal (PVT) greenhouse solar dryer under forced mode has been proposed and different parameters have been evaluated for different climatic condition of Indian Institute of Technology, New Delhi (28_350 N, 77_120E, 216 m above MSL), India. In the present study, radiation data and ambient air temperature have been taken from IMD (Indian Meteorological Department) Pune. Further, thermal modelling has been done for the PVT greenhouse dryer and different parameter such as crop temperature, greenhouse temperature, outlet air temperature and cell temperature have been calculated by the help of program made on MATLAB 2013a. Fair agreement has been found between theoretical and experimental data with correlation coefficient value (r) and root mean square percentage deviation (e) are 0.92 and 4.64, 0.99 and 0.97, 0.99 and 0.96 for solar cell, greenhouse room and crop temperature respectively. Further, on yearly basis useful thermal energy, useful electrical energy, useful equivalent thermal energy, thermal exergy and overall thermal efficiency have been calculated. Further, embodied energy, energy payback time, CO2 mitigation and carbon credit earn have also been calculated. It was found that payback time for system is 1.23 and 10 years on the basis of overall thermal energy and overall exergy basis respectively. © 2016 Elsevier Ltd

Energy

Exergoeconomic analysis of photovoltaic-thermal (PVT) mixed mode greenhouse solar dryer

A hybrid photovoltaic-thermal (PVT) greenhouse solar dryer under mixed mode has been proposed and different parameters have been evaluated for climatic condition of Indian Institute of Technology, New Delhi (28_350N, 77_120E, 216 m above MSL), India. Further thermal modelling has been developed for the PVT greenhouse dryer by considering different parameter namely crop, greenhouse and solar cell temperatures, etc. Numerical computations have been done with the help of program made on MATLAB 2013a and the results are validated with experimental values. Characteristic curves have been developed for drying and system efficiency with experimental validation. Further, an overall thermal energy and exergy have been calculated. Theoretical and experimental values of overall thermal energy found to be 1.92 kW h and 2.03 kW h respectively. It can be seen that there is good agreement between theoretical and experimental value with r = 0.98 and e = 10.76. Further validation has also been done for energy and exergy of PVT dryer. © 2016 Elsevier Ltd.

Performance analysis of photovoltaic-thermal (PVT) mixed mode greenhouse solar dryer

Present study is an attempt to study of different heat storage methods and their application for sustainable development. Solar energy is a prime source of energy which is responsible for other renewable sources directly or indirectly. The major drawback of solar energy is its availability in day time only. Thermal storage devices can overcome this drawback as they can store the energy in day time that can be utilized in off sunshine hours. In the present study classification of thermal storage methods has been done. Further different application of phase change material (PCM) has been discussed. Study shows that PCM can be successfully integrated nearly with all the solar thermal devices. This study will also help to understand to store maximum thermal energy that reduce the requirement of conventional fuels like coal, oil etc. Further, it will help in reducing greenhouse gasses and climatic changes. © 2016 IEEE.