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Reshmi Maity,N. P. Maity,K. Srinivasa Rao,Girija Sravani,K. Guha,S. Baishya 한국전기전자재료학회 2019 Transactions on Electrical and Electronic Material Vol.20 No.5
This paper models the fringing fi eld eff ects in a capacitive micromachined ultrasonic transducer (CMUT) structure for determining the sensitivity of the device. CMUT is used as a medical imaging component which can be an important module for sustainable healthcare system. The capacitance value of the device is evaluated based on Younes Ataiiyan’s method. To determine the equivalent capacitance of the device, the capacitances of the membrane, gap and silicon nitride insulating layer are associated in series. Mason’s modeling techniques are used to evaluate the membrane displacement. Circular membrane approximation model has been considered. Eff ects of the variation in membrane thickness, gap separation, and membrane radius on membrane displacement are investigated. The analytical prediction has been validated with the finite element method simulation results through PZFlex. Three dimensional modeling is carried out to accurately capture the characteristic behavior of the device. The agreements of both results are excellent which verifi es that fringing field effects exist in the device operation.
Target Application Based Design Approach for RF MEMS Switches using Artificial Neural Networks
Lakshmi Narayana Thalluri,Samuyelu Bommu,Sathuluri Mallikharjuna Rao,K. Srinivasa Rao,Koushik Guha,S. S. Kiran 한국전기전자재료학회 2022 Transactions on Electrical and Electronic Material Vol.23 No.5
In this paper, a target application-based design approach for RF MEMS switches using artifi cial neural networks (ANN) is presented. ANN approach is used to decide the dimensions of the RF MEMS switch for the targeted application. The ANN approach design and analysis is done using MATLAB. The results obtained by ANN method are validated using the FEM tool simulation, which show that the developed models have good accuracy over the range of switch dimension values for the intended application. The switch dimensions are extracted for L, S, C, X, Ku, K, and Ka-band applications using ANN. Eventually, a novel RF MEMS switch based on the ANN approach for C-band applications is proposed. The required pullin voltage will increase because of perforation, and this problem is handled by adding extra weight to the membrane with pillars and slabs. Analyzed load distribution in membrane with perforation. FEM design is implemented using solid mechanics and electrostatic-based Multi-physics in COMSOL environment. Diff erent studies, i.e., stationary, time-dependent, and frequency domain are performed to extract electrical, mechanical, and Radio Frequency parameters of the proposed design. The switch designed for C-band applications off ering an actuation voltage of 7.4 V, Insertion loss of − 0.2 dB, and Isolationloss of − 57 dB.
Jacobian Based Nonlinear Algorithms for Prediction of Optimized RF MEMS Switch Dimensions
Lakshmi Narayana Thalluri,M Aravind Kumar,Mohamed Sultan Mohamed Ali,N. Britto Martin Paul,K. Srinivasa Rao,Koushik Guha,S. S. Kiran 한국전기전자재료학회 2023 Transactions on Electrical and Electronic Material Vol.24 No.5
This communication discusses the role of nonlinear algorithms in training the neural network, which predicts the optimized RF MEMS switch dimensions. A dedicated dataset, i.e., DrTLN-RF-MEMS-SWITCH-DATASET-v1, was created by considering the most appropriate input and output variable suitable to predict the cantilever dimensions, crab leg and serpentine structure-based RF MEMS switches. The distinct artificial neural networks (ANN) performance is analysed using various training methods. The hardware implementation possible neural network algorithms, i.e., Fitting and Cascade Feed Forward Network, are considered for learning and prediction. The ANN algorithm's performance in predicting and optimizing RF MEMS switch is analysed using nonlinear training methods like Levenberg–Marquardt (LM) and Scaled Conjugate Gradient (SCG). The cascaded forward network with LM training combination offers the best performance compared with other varieties. A comprehensive study is performed using neural networks and finite element simulation results. The study revealed that the error percentage is below 15.08% for most of the parameters.
S. Chugh,R.K. Guha,Joydip Dhar 한국전산응용수학회 2022 Journal of Applied and Pure Mathematics Vol.4 No.1
An innovation diffusion model is proposed model consists of three classes, namely, a non-adopter class, adopter class innovation-I, and adopter class innovation-II in a partially competitive and cooperative market. The proposed model is analyzed with the help of the qualitative theory of a system of ordinary differential equations. Basic influence numbers associated with first and second innovation {R}_{0_1} and {R}_{0_2} respectively in the absence of each other are quantified. Then the overall basic influence number ({R}_{0}) of the system is assessed for analyzing stability in the market in different situations. Sensitivity analysis of basic influence numbers associated with first and second innovation in the absence of each other is carried out. Numerical simulation supports our analytical findings.
CHUGH, S.,GUHA, R.K.,DHAR, JOYDIP The Korean Society for Computational and Applied M 2022 Journal of applied and pure mathematics Vol.4 No.1/2
An innovation diffusion model is proposed model consists of three classes, namely, a non-adopter class, adopter class innovation-I, and adopter class innovation-II in a partially competitive and cooperative market. The proposed model is analyzed with the help of the qualitative theory of a system of ordinary differential equations. Basic influence numbers associated with first and second innovation $R_{0_1}$ and $R_{0_2}$ respectively in the absence of each other are quantified. Then the overall basic influence number (R<sub>0</sub>) of the system is assessed for analyzing stability in the market in different situations. Sensitivity analysis of basic influence numbers associated with first and second innovation in the absence of each other is carried out. Numerical simulation supports our analytical findings.
Modeling of a Switched Reluctance Motor in Sensorless and 'With Sensor' Modes
Bhuvaneswari G.,Thakurta Sarit Guha,Rao P. Srinivasa,Murthy S.S. The Korean Institute of Power Electronics 2006 JOURNAL OF POWER ELECTRONICS Vol.6 No.4
Switched Reluctance Motors (SRM) have emerged as viable alternatives to other adjustable speed drives such as vector controlled induction motors (VCIM) and permanent magnet brush-less (PMBL) motors due to their simple construction, ease of control, low inertia and higher operating speeds. However, the indispensability of the rotor position sensor in an SRM for its successful operation increases its cost, apart from causing other problems like decreasing its reliability and inability to operate in adverse environmental conditions. In this paper, a new sensorless control scheme for the SRM is advocated. The required fundamental data is obtained by analyzing the SRM using the Finite Elements (FE) package MAXWELL. The drive is studied in both 'with sensor' and 'sensorless' modes and a comparison of the performances, in both cases, is presented for various operating conditions.
Modeling of a Switched Reluctance Motor in Sensorless and “With Sensor” Modes
G. Bhuvaneswari,Sarit Guha Thakurta,P. Srinivasa Rao,S. S. Murthy 전력전자학회 2006 JOURNAL OF POWER ELECTRONICS Vol.6 No.4
Switched Reluctance Motors (SRM) have emerged as viable alternatives to other adjustable speed drives such as vector controlled induction motors (VCIM) and permanent magnet brush-less (PMBL) motors due to their simple construction, ease of control, low inertia and higher operating speeds. However, the indispensability of the rotor position sensor in an SRM for its successful operation increases its cost, apart from causing other problems like decreasing its reliability and inability to operate in adverse environmental conditions. In this paper, a new sensorless control scheme for the SRM is advocated. The required fundamental data is obtained by analyzing the SRM using the Finite Elements (FE) package MAXWELL. The drive is studied in both “with sensor” and “sensorless” modes and a comparison of the performances, in both cases, is presented for various operating conditions.
Optical and Electrical Properties of Bulk-grown Ternary In_xGa_(1−x)As
Y. K. Yeo,A. C. Bergstrom,R. L. Hengehold,J. W. Wei,S. Guha,L. P. Gonzalez,G. Rajagopalan,류미이 한국물리학회 2011 THE JOURNAL OF THE KOREAN PHYSICAL SOCIETY Vol.58 No.51
Bulk ternary In_xGa_(1−x)As polycrystals were grown using the vertical Bridgman technique. The optical and electrical properties of these bulk In_xGa_(1−x)As were investigated as a function of indium mole fraction from 0.75 to 0.99 by using photoluminescence (PL) and Hall-effect measurements. All samples showed good infrared transmission. A free exciton (FX) transition peak was observed from all bulk In_xGa_(1−x)As samples, and it redshifted from 0.568 to 0.412 eV as the indium mole fraction increased from 0.75 to 0.99. Bandgaps estimated from the indium compositionand temperature-dependent FX peaks generally followed the theoretically calculated bandgaps. All as-grown In_xGa_(1−x)As samples showed n-type conductivity. Although all bulk In_xGa_(1−x)As samples showed good optical transmissions and PL transitions, as well as high carrier mobilitites, they exhibited some random compositional fluctuations across the sample area.