Faculty Publications
Permanent URI for this communityhttps://idr.nitk.ac.in/handle/123456789/18736
Publications by NITK Faculty
Browse
11 results
Search Results
Item Autonomic computing in medical informatics: Accessing and retrieval of EMR(2009) Chandrashekharan, K.; Rao, A.; Sruthi, B.Medical informatics is an interdisciplinary field of research, where a great deal of collaboration is required to achieve efficient solutions. In this paper we bring in the concept of implementing autonomic computing in medical informatics. The work is in the aspect of maintaining and accessing patient's medical records and/or further retrieval of data in an efficient way with the role of autonomic computing in it. We exhibit a solution in the form of an automated system for EMR (electronic medical record), in this context. © 2009 IEEE.Item Energy efficient wireless sensor networks using asymmetric distributed source coding(2013) Rao, A.; Kulkarni, M.Wireless Sensor Networks (WSNs) are networks of sensor nodes deployed over a geographical area to perform a specific task. WSNs pose many design challenges. Energy conservation is one such design issue. In literature a wide range of solutions addressing this issue have been proposed. Generally WSNs are densely deployed. Thus the nodes with the close proximity are more likely to have the same data. Transmission of such non-aggregated data may lead to an inefficient energy management. Hence the data fusion has to be performed at the nodes so as to combine the redundant information into a single data unit. Distributed Source Coding is an efficient approach in achieving this task. In this paper an attempt has been made in modeling such a system. Various energy efficient codes were considered for the analysis. System performance in terms of energy efficiency has been made. Copyright © 2013 SPIE.Item Gaussian approximation using integer sequences(Springer Verlag service@springer.de, 2014) Rajan, A.; Rao, A.; Vittal Rao, R.; Jamadagni, H.S.The need for generating samples that approximate statistical distributions within reasonable error limits and with less computational cost, necessitates the search for alternatives. In this work, we focus on the approximation of Gaussian distribution using the convolution of integer sequences. The results show that we can approximate Gaussian profile within 1% error. Though Bessel function based discrete kernels have been proposed earlier, they involve computations on real numbers and hence increasing the computational complexity. However, the integer sequence based Gaussian approximation, discussed in this paper, offer a low cost alternative to the one using Bessel functions. © Springer International Publishing Switzerland 2014.Item Modeling and experimental studies on the dynamics of bolted joint structure: Comparison of three vibration-based techniques for structural health monitoring(Springer Science and Business Media Deutschland GmbH info@springer-sbm.com, 2020) Deka, A.; Rao, A.; Kamath, S.; Gaurav, A.; Gangadharan, K.V.Detection of inadequate tightening in bolted joints is quintessential to ensure structural rigidity and to prevent catastrophic failure. Studies show that 30% of assembly failures occur due to inadequate tightening. In the present study, three vibration-based techniques are presented and compared to detect inadequate tightening of bolted joints. Variation in the damped natural frequency, variation in the damping ratio, and variation in the dynamic joint stiffness are studied with varying tightening torques in the bolted joint. The results show that all the three dynamic parameters vary with the tightness of the bolted joint. Dynamic joint stiffness varies significantly as opposed to the damping ratio and damped natural frequency as tightening torque reduces. In order to verify the results of dynamic stiffness method, ANSYS is used to model and analyze the joint. The experimental setup used to calculate the parameters consists of two Euler–Bernoulli beams connected with single lap bolted joint. © Springer Nature Singapore Pte Ltd 2020.Item MIMO based radio-over-fiber link for millimeter wave generation using external optical modulator(American Institute of Physics, 2024) Meena, K.S.R.; Rao, A.; Singh, M.In this paper, photonically assisted millimeter wave signal generation techniques are proposed for modern space applications. For this, two designs are investigated with different optical modulators, namely, amplitude modulator and Dual Drive-Mach Zehnder Modulator (DD-MZM). A 2*2 Wavelength Division Multiplexing (WDM) transmitter with a 100 GHz frequency spacing is used to broadcast Multiple-Input Multiple-Output (MIMO) signals, and it encodes the signals using a 1Gbps pseudo-random bit sequence with return-to-zero coding. The Electrical Constellation Visualizer is used to examine the distortion in the proposed Radio over Fiber (RoF) links. The opti-system software simulation for DD-MZM design confirms a high-frequency millimeter wave signal with 60 dBm optical sideband suppression ratio (OSSR) and radio-frequency spurious suppression ratio (RFSSR) 72 dBm. Whereas Amplitude Modulator based architecture produces mm-wave signals with high Q-factor and low loss. Therefore, the merging of MIMO and RoF technology is a better solution for generating mm-wave signals for next-generation communication systems. © 2024 Author(s).Item The electrocardiogram is a representative signal containing information about the condition of the heart. The shape and size of the P-QRS-T wave, the time intervals between its various peaks, etc. may contain useful information about the nature of disease afflicting the heart. However, these subtle details cannot be directly monitored by the human observer. Besides, since bio-signals are highly subjective, the symptoms may appear at random in the time scale. Therefore, the signal parameters, extracted and analysed using computers, are highly useful in diagnostics. This paper deals with the classification of certain diseases using artificial neural network (ANN) and fuzzy equivalence relations. The heart rate variability is used as the base signal from which certain parameters are extracted and presented to the ANN for classification. The same data is also used for fuzzy equivalence classifier. The feedforward architecture ANN classifier is seen to be correct in about 85% of the test cases, and the fuzzy classifier yields correct classification in over 90% of the cases. © 2002 Pattern Recognition Society. Published by Elsevier Science Ltd. All rights reserved.(Classification of heart rate data using artificial neural network and fuzzy equivalence relation) Acharya, A.U.; Subbanna Bhat, P.; Iyengar, S.S.; Rao, A.; Dua, S.2003Item Analysis of heart rate variation (HRV) has become a popular non-invasive tool for assessing the activities of the autonomic nervous system (ANS). HRV analysis is based on the concept that fast fluctuations may specifically reflect changes of sympathetic and vagal activity. It shows that the structure generating the signal is not simply linear, but also involves nonlinear contributions. These signals are essentially non-stationary; may contain indicators of current disease, or even warnings about impending diseases. The indicators may be present at all times or may occur at random in the time scale. However, to study and pinpoint abnormalities in voluminous data collected over several hours is strenuous and time consuming. This paper presents the continuous time wavelet analysis of heart rate variability signal for disease identification. Fractal dimension (FD) of heart rate signals are calculated and compared with the wavelet analysis patterns. The FD obtained indicates more than 90% confidence interval for all the classes studied. © 2005 Elsevier SAS. All rights reserved.(Analysis of cardiac health using fractal dimension and wavelet transformation) Acharya, A.U.; Subbanna Bhat, P.; Kannathal, N.; Rao, A.; Lim, C.M.2005Item Investigation on structural, magneto-transport, magnetic and thermal properties of La0.8Ca0.2-xBaxMnO3 (0 ? x ? 0.2) manganites(Elsevier Ltd, 2015) Manjunatha, S.O.; Rao, A.; Subhashini, u.; Okram, G.S.A systematic study on the structural, electrical, magnetic and thermo-electric properties of La0.8BaxCa0.2-xMnO3 (0 ? x ? 0.2) manganites is carried out in the present work. The samples have been prepared using solid state reaction technique. All the samples are single phased. It is seen that Ba-doping introduces a structural phase transformation viz. from rhombohedral to cubic system. Electric and magnetic studies respectively show that the metal-insulator transition temperature, TMI and Curie temperature, TC increase with Ba-content. Magneto-resistance (MR) data shows that it decreases with Ba-doping. Analyses of the electrical transport data in metallic region i.e. T < TMI shows that the electrical transport is governed predominantly by electron-electron scattering process. On the other hand, the adiabatic small polaron hopping (ASPH) model is appropriate in the high-temperature insulating range viz. T > TMI. We have used the electrical resistivity data in the entire temperature range (50-300 K) and analyzed using the phenomenological percolation model which is based on the phase segregation mechanism. We have analyzed the Seebeck coefficient data which reveals that the small polaron hopping mechanism is operative in high temperature regime and the low temperature region is examined by taking into account the impurity, electron-magnon scattering, and spin wave fluctuation terms. It is established that the electron-magnon scattering is dominating for the thermoelectric transport below TMI. © 2015 Elsevier B.V.Item Influence of annealing on the linear and nonlinear optical properties of Mn doped ZnO thin films examined by z-scan technique in CW regime(Elsevier B.V., 2016) Nagaraja, K.K.; Pramodini, S.; Poornesh, P.; Rao, A.; Nagaraja, H.S.We present the studies on the influence of annealing on the third-order nonlinear optical properties of RF magnetron sputtered manganese doped zinc oxide (MZO) thin films with different doping concentration. It is revealed that the incorporation of Mn into ZnO and annealing lead to prominent changes in the third order nonlinearity. Nonlinear optical measurements were carried out by employing the z-scan technique using a continuous wave (CW) He-Ne laser of 633 nm. The z-scan results reveal that the films exhibit self-defocusing thermal nonlinearity. The third-order nonlinear optical susceptibility ?(3) was found to be of the order of 10-3 esu and 10-2 esu for annealed MZO thin films at 200 °C and 400 °C respectively. The dependence of grain size on the observed nonlinearity was revealed by atomic force microscopy analysis. Optical limiting studies were carried out for a range of input power levels and an optical limiting of about ?8 mW was observed indicating the possible application for photonic devices. © 2016 Elsevier B.V. All rights reserved.Item A systematic investigation on structural, electrical, linear and nonlinear optical properties of Zn:CdO thin films for optoelectronic applications(Elsevier B.V., 2021) Nagaraja, B.S.; Gurumurthy, S.C.; Bairy, R.; Koduri, K.; K, B.; Rao, A.In the present work, a systematic study on structural, electrical, linear, and nonlinear optical properties of Zn doped CdO thin films prepared by Spray Pyrolysis (SP) technique is reported. X-ray diffraction (XRD) studies revealed the cubic, wurtzite structure, and polycrystalline nature of all the films. The observed results showed a decrease in lattice constant and unit cell volume with an increase in Zn doping concentration. Morphology study confirms uniform distribution of spherical grain-like structure with small voids. An increase in direct and indirect bandgap is observed with doping concentration up to 5 wt%, and the trend reverses at higher concentration. The significant effect of Zn doping on optical parameters such as absorption coefficient, extension coefficient, refractive index, optical dielectric constant, and optical conductivities are calculated for all thin films. Further, the optical studies were used to analyze the linear susceptibility, third-order nonlinear optical susceptibility, and nonlinear refractive index of the films. The observed values for ?(1),?(3) and n2 are in the range from 0.03 to 0.09 esu, 3.51×10?16 to 1.02×10?14 esu, and 1.09×10?14 to 2.67×10?13 esu for pure and Zn doped thin films respectively. Hall coefficient and electrical studies indicate that the Zn doping influences the electrical properties. An n-type and ohmic behavior is also observed for these films. Optical and electrical results suggest that these Zn:CdO films can be a potential candidate for optoelectronic applications. © 2021 Elsevier B.V.