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Hyderabad, India

Gupta G.S.,VNR VJIET | Harinath P.N.V.,M. Technology in Advanced Manufacturing Systems
Materials Today: Proceedings | Year: 2015

This paper is on an experimental investigation for evaluating physical, mechanical and thermal properties of an ablative phenolic laminates by manufacturing and testing them. These are manufactured by changing various parameters like with and without reinforcement of micro silica powder of 15 weight percentage of matrix as filler material and the ply orientation of 0° and 35° rosette. These properties of prepared materials have been tabulated and compared as part of analysis. Literature study reveals that S-Glass laminates exhibit better thermal properties than E glass laminates. Hence, this investigation is carried out for enhancement of properties in E-glass laminates. © 2015 Elsevier Ltd. Source


Yadlapalli R.T.,Andhra University | Kotapati A.,VNR VJIET
International Journal of Power Electronics | Year: 2014

The switched-mode power supplies are widely used in very low voltage and high-power applications where large conversion ratios are required. In such cases, the quadratic buck converter is the suitable one compared to buck, cascaded buck and multi-phase choppers, because of their limitations in switching frequency and losses. This paper presents mathematical analysis, design and simulation of a quadratic buck converter using fixed frequency Pulse-Width Modulation (PWM)-based Sliding-Mode (SM) controller in order to obtain fast dynamic performance. The design aspects include choice of sliding surface, deriving existing and stability conditions, control parameter selection and their analysis. The performance of the proposed converter is compared with the conventional Average Current-Mode (ACM) controller. In average current mode, the tuning of the PI controller for the inner current loop and outer voltage loop is done using bode plots. The simulation results for the two types of controllers are represented for analysing dynamic performance, as well as line and load regulations. Copyright © 2014 Inderscience Enterprises Ltd. Source


Yadlapalli R.T.,Andhra University | Kotapati A.,VNR VJIET
International Journal of Power Electronics | Year: 2014

This paper presents mathematical analysis, design and simulation of a quadratic buck converter used as LED lamp driver, and the performance of the converter is compared with two different control strategies. The objective is to provide tight regulation of the LED current that can operate over a wide range of DC input voltages. The first control strategy is the non-linear Sliding-Mode (SM) current controller, and its design aspects include choice of sliding surface, deriving existing and stability conditions, control parameter selection and their analysis. This paper also throws light on Average Current-Mode (ACM) controller. The operation, modelling, designing and transfer function derivation for the inner current and outer voltage loops of the quadratic buck converter are presented. The tuning of controllers for the ACM controller is done using Bode plots, for achieving desired phase and gain margins. The simulation is done using PSIM software and the results are presented. Copyright © 2014 Inderscience Enterprises Ltd. Source


Usharani Y.,VNR VJIET | Sammulal P.,Jawaharlal Nehru Technological University Anantapur
2015 IEEE International Conference on Computational Intelligence and Computing Research, ICCIC 2015 | Year: 2015

Imputation of missing attribute values in medical datasets for extracting hidden knowledge from medical datasets is an interesting research topic of interest which is very challenging. One cannot eliminate missing values in medical records. The reason may be because some tests may not been conducted as they are cost effective, values missed when conducting clinical trials, values may not have been recorded to name some of the reasons. Data mining researchers have been proposing various approaches to find and impute missing values. In this paper, we propose a novel imputation approach for fixing missing values. The approach is based on clustering concept and aims at dimensionality reduction of the records. This serves the need to use the same records of lower dimension to be used for clustering and classification of medical records to arrive at accurate decision prediction. The case study discussed shows that the missing values can be fixed and imputed efficiently by achieving dimensionality reduction. The proposed approach for imputation also achieved dimensionality reduction to perform efficient prediction of missing values. © 2015 IEEE. Source


Lakshmi A.P.,VNR VJIET
2014 IEEE Global Conference on Signal and Information Processing, GlobalSIP 2014 | Year: 2014

This paper presents a non-invasive method to differentiate malignant and benign brain tumours using Lab VIEW Software. Brain tumours are atypical growth of cells in the brain[l]. It is important to diagnose these tumours as malignant or benign as early as possible after detection. Benign tumours are encapsulated and have a controlled growth whereas malignant tumours are not encapsulated and lead to necrosis and pushing aside of neighbouring tissue which causes the build-up of cerebral fluids and oedema in the brain compared to benign tumours. Hence, malignant tumours have a much more severe impact on the brain tissue than benign tumours. So far in clinical practice, only pathology tests have been used to diagnose tumours. This paper is a step towards non-invasive identification of malignant and benign tumours. Here a script was developed in N1 Vision Assistant software which identifies tumours based on the amount of oedema, fluids and infection in the brain which is reflected in MRI scans[2]. © 2014 IEEE. Source

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