Velagapudi Ramakrishna Siddhartha Engineering College

About: Velagapudi Ramakrishna Siddhartha Engineering College is a based out in . It is known for research contribution in the topics: Computer science & Antenna (radio). The organization has 1307 authors who have published 1155 publications receiving 6163 citations.

Correction of Ocular Artifacts from EEG by DWT with an Improved Thresholding

Abstract: Electroencephalogram (EEG) signals are widely being used for analyzing the activities of brain. It is extensively used for diagnosing different central nervous system disorders such as Alzheimer’s, Parkinson’s, seizures, epilepsy, etc. Ocular activity creates significant artifacts in EEG recordings. Analysis of the EEG and obtaining clinical information is difficult because of these noise sources. This paper proposes discrete wavelet transform (DWT) based denoising method with new statistical thresholding for single channel EEG signal. This method is evaluated on EEG signals taken from polysomnographic records, eegmmidb database. The effectiveness of the proposed method was measured using parameters such as signal to noise ratio (SNR), artifact rejection ratio (ARR) and comparing with the existing threshold method. Result of this study reveals that DWT with proposed thresholding method has shown superior performance in terms of SNR and ARR and effectively eliminates ocular artifacts.

A Simulated Study on Impact of Preference Function on Network Selection

Abstract: Objectives: Preference function represents the decision maker attitude towards the differences between networks for a given criterion. This paper studies the impact of various preference functions on network selection in a heterogeneous wireless environment. Methods/Statistical Analysis: A multiple wireless network environment is considered and network selection is performed by assessing each network with respect to quality of service, application requirements and user preferences. As the decision process involves multiple parameters, the problem is viewed to be Multiple Attribute Decision Making (MADM). For this model, Preference Ranking Organization Method for Enrichment Evaluations (PROMETHEE) an outranking MADM method is applied to select best network. Findings: PROMETHEE performs pair-wise comparison of the networks against each criterion and generates outranking flows. The positive and negative outranking flows indicate the degree with which a network is preferable or not, when compared to other networks on a specific criterion. Based on the net outranking flow, the networks are ranked from best to worst. The best ranked network is the optimal network. However, the ranking order is greatly influenced by the preference function. Application/Improvements: This paper investigates the effect of various preference functions on network selection, accuracy, ranking abnormality and network congestion for voice and streaming applications.

Recent Developments in Earth Pressure Reduction Techniques

Abstract: Rigid earth retaining structures are common civil engineering structures and they are constructed to retain the backfill soil. The evaluation of lateral earth pressure on retaining walls under due to retaining soil and external loads during the service life is vital as it significantly influences the cost of the project. Lateral earth thrust on rigid retaining walls from the backfill can be minimized by a suitable technique, notably using lightweight backfill, placing a compressible inclusion between the backfill and the retaining wall, or by providing one or more relief shelves along the height of the wall. This paper discusses recent studies carried out at IIT Bombay to reduce long-term lateral thrust on rigid retaining walls retaining cohesionless backfill using compressible geo-inclusion. The laboratory studies on geofoam samples reveal that Young’s modulus, yield stress, and compressible strength of the geofoam reduces with time. Also, the estimated creep strains obtained from Time–Temperature–Stress Superposition (TTSS) accelerated creep testing method at the end of 100 years was in the range of 2.1–2.4%. The isolation efficiency of the geofoam, which is defined as the ratio of reduction of lateral thrust due to the provision of geofoam at the soil–wall interface and the lateral thrust without geofoam, obtained from pseudo-long-term studies was more compared to that of short-term studies by 2.4–8.1%. The studies, for the first time, reveal that geofoam inclusion considerably reduces the lateral thrust on the wall not only in short-term but in long-term as well.

Experimental Investigation on Friction Stir Welding of Dissimilar Alloys AA7075 and Pure Copper: Effect of Tool Material and Process Parameters on Mechanical Properties

Abstract: In this study was analyzed the effect of tool material, tool geometry and process parameters on mechanical properties and microstructure of friction stir dissimilar welded AA7075 and pure copper joints. Different welded samples were produced by varying tool material H13 and HSS, tool geometry like cone pin length 4.8 and 5 mm, the rotational speeds 750 and 900 RPM, and in all experiments, the feed and tilting angle are constant at 16 mm/min and 2°. These parameters were used for better understanding the effect of dissimilar AA7075 and pure copper welded joints on tensile strength, microstructure and hardness. Results showed that the good strengthen AA7075 and pure copper friction stir welded joints could be obtained when a tool is H13 material and cone-shaped tool. H13 tool gives quality AA7075 and pure copper friction stir welded joints compare to HSS tool at speed of 750 Rpm, feed of 16 mm/min and tilting angle 2°.