Journal Articles
Permanent URI for this collectionhttps://idr.nitk.ac.in/handle/123456789/19884
Browse
13 results
Search Results
Item Current and Emerging Diagnostic Imaging-Based Techniques for Assessment of Osteoporosis and Fracture Risk(Institute of Electrical and Electronics Engineers, 2018) Areeckal, A.S.; Kocher, M.; Sumam David, S.Osteoporosis is a metabolic bone disorder characterized by low bone mass, degradation of bone microarchitecture, and susceptibility to fracture. It is a growing major health concern across the world, especially in the elderly population. Osteoporosis can cause hip or spinal fractures that may lead to high morbidity and socio-economic burden. Therefore, there is a need for early diagnosis of osteoporosis and prediction of fragility fracture risk. In this review, state of the art and recent advances in imaging techniques for diagnosis of osteoporosis and fracture risk assessment have been explored. Segmentation methods used to segment the regions of interest and texture analysis methods used for classification of healthy and osteoporotic subjects are also presented. Furthermore, challenges posed by the current diagnostic tools have been studied and feasible solutions to circumvent the limitations are discussed. Early diagnosis of osteoporosis and prediction of fracture risk require the development of highly precise and accurate low-cost diagnostic techniques that would help the elderly population in low economies. © 2008-2011 IEEE.Item Face Recognition (FR) systems are increasingly gaining more importance. Face detection and tracking in a complex scene forms the first step in building a practical FR system. In this paper, a method to detect and track human faces in color image sequences is described. Skin color classification and morphological segmentation is used to detect face(s) in the first frame. These detected faces are tracked over subsequent frames by using the position of the faces in the first frame as the marker and detecting for skin in the localized region. Specific advantages of this approach are that skin color analysis method is simple and powerful, and the system can be used to detect/track multiple faces. © 2002 Taylor & Francis Group, LLC.(Human face detection and tracking using skin color modeling and connected component operators) Kuchi, P.; Gabbur, P.; Subbanna Bhat, P.; Sumam David, S.2002Item Efficient Distributed Video Coding based on principle of syndrome coding(Inderscience Publishers, 2011) Aparna., P.; Sumam David, S.Distributed Video Coding (DVC) is a new video coding paradigm, the main objective of which is to reduce the encoder complexity to support a separate class of uplink-friendly applications like wireless video applications, besides achieving the rate-distortion performance of conventional video coders. In this paper, we describe and present the simulation results of the video coding method based on the principle of distributed source coding using Golay codes and then propose an improvement to it. In this, the side information is improved by performing a very coarse motion search at the encoder and transmitting the position of the side information block as the hash information to the decoder, which will help the decoder to perform motion estimation. Copyright © 2011 Inderscience Enterprises Ltd.Item Real-time implementation of a novel vector-locked loop for synchronous extraction of harmonics in power systems(2012) Gonda, J.M.; Sumam David, S.The extraction of the harmonics and or the fundamental from a distorted waveform is an important process in the implementation of custom power devices. Several schemes have been proposed in the past towards this. In this paper the principle of operation, performance, and design aspects of a novel scheme of a vector-locked loop (VLL) for synchronous extraction of the harmonics and or the fundamental from a distorted periodic waveform is briefly described and real-time hardware emulation results are presented. Main features of the VLL are: simplicity, excellent insensitivity to harmonics, noise rejection, availability of both fundamental and harmonics without additional processing, and the good speed of operation. Some results from the real-time hardware emulation of the scheme on a dSPACE-Modular system are presented and compared with the results from MATLAB®/Simulink®.Item Implementation of comprehensive address generator for digital signal processor(2013) Ramesh Kini, R.M.; Sumam David, S.The performance of signal-processing algorithms implemented in hardware depends on the efficiency of datapath, memory speed and address computation. Pattern of data access in signal-processing applications is complex and it is desirable to execute the innermost loop of a kernel in a single-clock cycle. This necessitates the generation of typically three addresses per clock: two addresses for data sample/coefficient and one for the storage of processed data. Most of the Reconfigurable Processors, designed for multimedia, focus on mapping the multimedia applications written in a high-level language directly on to the reconfigurable fabric, implying the use of same datapath resources for kernel processing and address generation. This results in inconsistent and non-optimal use of finite datapath resources. Presence of a set of dedicated, efficient Address Generator Units (AGUs) helps in better utilisation of the datapath elements by using them only for kernel operations; and will certainly enhance the performance. This article focuses on the design and application-specific integrated circuit implementation of address generators for complex addressing modes required by multimedia signal-processing kernels. A novel algorithm and hardware for AGU is developed for accessing data and coefficients in a bit-reversed order for fast Fourier transform kernel spanning over log 2 N stages, AGUs for zig-zag-ordered data access for entropy coding after Discrete Cosine Transform (DCT), convolution kernels with stored/streaming data, accessing data for motion estimation using the block-matching technique and other conventional addressing modes. When mapped to hardware, they scale linearly in gate complexity with increase in the size. © 2013 Copyright Taylor and Francis Group, LLC.Item Real-time implementation of an amplitude-locked loop: A validation on the dSPACE DS1006-based platform(2013) Gonda, J.M.; Sumam David, S.The extraction of harmonics and/or the fundamental from a distorted waveform is an important process in the implementation of custom-power devices. Several schemes towards this have been proposed in the past. Among these, the algorithms based on synchronous (with respect to the supply voltages) extraction (both in phase and amplitude) have certain established advantages over the others. Amplitude-locked loops (ALLs) have been in use in signal-communication systems but are limited to sinusoidal inputs. There is a need for fast and rugged algorithms to synchronously extract harmonics and/or the fundamental from a distorted waveform in many power system applications. In this paper a real-time implementation of a novel scheme, which is based on an adaptation of an ALL, is presented for synchronous extraction of harmonics and/or the fundamental from a distorted periodic waveform. The operation of the algorithm, its performance, and its design aspects are briey discussed. The main features of this ALL are simplicity, speed of operation, noise rejection, availability of both fundamental and harmonics without much additional processing, and excellent insensitivity to distortion (robustness). Furthermore, it is applicable to single-phase or 3-phase systems. This paper reports a real-time hardware implementation of the algorithm, thereby validating it. The algorithm is implemented on a real-time hardware-emulation platform, a dSPACE modular system (configured around the DS1006 processor board). It is tested for various cases of interest and the results are presented. © Tübi?tak;.Item Early diagnosis of osteoporosis using radiogrammetry and texture analysis from hand and wrist radiographs in Indian population(Springer London, 2018) Areeckal, A.S.; Jayasheelan, N.; Kamath, J.; Zawadynski, S.; Kocher, M.; Sumam David, S.Summary: We propose an automated low cost tool for early diagnosis of onset of osteoporosis using cortical radiogrammetry and cancellous texture analysis from hand and wrist radiographs. The trained classifier model gives a good performance accuracy in classifying between healthy and low bone mass subjects. Introduction: We propose a low cost automated diagnostic tool for early diagnosis of reduction in bone mass using cortical radiogrammetry and cancellous texture analysis of hand and wrist radiographs. Reduction in bone mass could lead to osteoporosis, a disease observed to be increasingly occurring at a younger age in recent times. Dual X-ray absorptiometry (DXA), currently used in clinical practice, is expensive and available only in urban areas in India. Therefore, there is a need to develop a low cost diagnostic tool in order to facilitate large-scale screening of people for early diagnosis of osteoporosis at primary health centers. Methods: Cortical radiogrammetry from third metacarpal bone shaft and cancellous texture analysis from distal radius are used to detect low bone mass. Cortical bone indices and cancellous features using Gray Level Run Length Matrices and Laws’ masks are extracted. A neural network classifier is trained using these features to classify healthy subjects and subjects having low bone mass. Results: In our pilot study, the proposed segmentation method shows 89.9 and 93.5% accuracy in detecting third metacarpal bone shaft and distal radius ROI, respectively. The trained classifier shows training accuracy of 94.3% and test accuracy of 88.5%. Conclusion: An automated diagnostic technique for early diagnosis of onset of osteoporosis is developed using cortical radiogrammetric measurements and cancellous texture analysis of hand and wrist radiographs. The work shows that a combination of cortical and cancellous features improves the diagnostic ability and is a promising low cost tool for early diagnosis of increased risk of osteoporosis. © 2017, International Osteoporosis Foundation and National Osteoporosis Foundation.Item Combined radiogrammetry and texture analysis for early diagnosis of osteoporosis using Indian and Swiss data(Elsevier Ltd, 2018) Areeckal, A.S.; Kamath, J.; Zawadynski, S.; Kocher, M.; Sumam David, S.Osteoporosis is a bone disorder characterized by bone loss and decreased bone strength. The most widely used technique for detection of osteoporosis is the measurement of bone mineral density (BMD) using dual energy X-ray absorptiometry (DXA). But DXA scans are expensive and not widely available in low-income economies. In this paper, we propose a low cost pre-screening tool for the detection of low bone mass, using cortical radiogrammetry of third metacarpal bone and trabecular texture analysis of distal radius from hand and wrist radiographs. An automatic segmentation algorithm to automatically locate and segment the third metacarpal bone and distal radius region of interest (ROI) is proposed. Cortical measurements such as combined cortical thickness (CCT), cortical area (CA), percent cortical area (PCA) and Barnett Nordin index (BNI) were taken from the shaft of third metacarpal bone. Texture analysis of trabecular network at the distal radius was performed using features obtained from histogram, gray level Co-occurrence matrix (GLCM) and morphological gradient method (MGM). The significant cortical and texture features were selected using independent sample t-test and used to train classifiers to classify healthy subjects and people with low bone mass. The proposed pre-screening tool was validated on two ethnic groups, Indian sample population and Swiss sample population. Data of 134 subjects from Indian sample population and 65 subjects from Swiss sample population were analysed. The proposed automatic segmentation approach shows a detection accuracy of 86% in detecting the third metacarpal bone shaft and 90% in accurately locating the distal radius ROI. Comparison of the automatic radiogrammetry to the ground truth provided by experts show a mean absolute error of 0.04 mm for cortical width of healthy group, 0.12 mm for cortical width of low bone mass group, 0.22 mm for medullary width of healthy group, and 0.26 mm for medullary width of low bone mass group. Independent sample t-test was used to select the most discriminant features, to be used as input for training the classifiers. Pearson correlation analysis of the extracted features with DXA-BMD of lumbar spine (DXA-LS) shows significantly high correlation values. Classifiers were trained with the most significant features in the Indian and Swiss sample data. Weighted KNN classifier shows the best test accuracy of 78% for Indian sample data and 100% for Swiss sample data. Hence, combined automatic radiogrammetry and texture analysis is shown to be an effective low cost pre-screening tool for early diagnosis of osteoporosis. © 2018 Elsevier LtdItem Choice of engineering education among girls in India - the journey so far(Rajarambapu Institute Of Technology, 2021) Geethalakshmi, P.M.; Sumam David, S.; Thomas, V.V.Gender disparity in engineering enrolment is quite significant although there is only a very narrow gap in girls’ enrollment in higher education in India. The overall enrolment of girls in engineering programs is 27.5%. By affirmative action of introducing supernumerary quota for girls, Ministry of Education targets to increase the enrolment of girls which was 8% and 14 % respectively in IITs and NITs in 2016-17 to 20% in 2020-21. Therefore, it is essential to explore the reasons behind the reluctance of girls in choosing engineering education, even when the nature of engineering jobs has evolved to be gender neutral. It is even more significant now when National Education Policy (NEP) 2020 is targeting to achieve a Gross Enrolment Ratio (GER) of 50 % by 2035 from the current 27 %. This paper reviews the existing studies to understand the nature of influence of both external and internal factors and their interaction on the girls’ choice of higher education. Literature review of the research articles for two decades was conducted. It includes both published and unpublished work on the subject. There are no studies conducted nationwide, post 2004 to address the reasons for disproportionate representation of girls in engineering education in India. It is found that the findings are contextual in nature with respect to culture of the society. In, particular, the influence of parental perception influences the association of gender with engineering studies, among the girls. Awareness and exposure of the nature of engineering jobs among parents and the girls can bring in the desired change. © 2021, Rajarambapu Institute Of Technology. All rights reserved.Item Characterization of Fault Signature Due to Combined Air-Gap Eccentricity and Rotor Faults in Induction Motors(Praise Worthy Prize S.r.l, 2021) Bindu, S.; Sumam David, S.; Thomas, V.V.An accurate means of non-invasive condition monitoring of the popular industrial drive, three-phase squirrel-cage induction motor, can help to avoid unscheduled maintenance downtime and loss. Faults like air-gap eccentricity can exist even in a newly assembled drive and hence may co-exist with other internal defects. Despite it being a possible situation, the occurrence of simultaneous faults has seldom been studied. Therefore, there is a need for identifying fault signatures of combined fault conditions in a non-invasive manner. This paper presents a detailed model-based study on a three-phase squirrel-cage induction motor with the simultaneous existence of broken rotor-bar and air-gap mixed eccentricity faults using spectral analysis of stator current, instantaneous power, and estimated air-gap torque signals. The modelling of the machine is done using the Multiple Coupled Circuit method and modified to model the presence of the combined fault conditions. A comparative evaluation with various fault conditions and their severity is carried out by spectral analysis, and unique slip-dependent frequency components are identified in the spectra of diagnostic signals. This fault characterization is the most significant contribution of this paper. © 2021 Praise Worthy Prize S.r.l.-All rights reserved.