THREE-DIMENSIONAL LORENTZIAN PARA-KENMOTSU MANIFOLDS AND YAMABE SOLITONS

( Pankaj ),( Sudhakar K. Chaubey ),( Rajendra Prasad ) 호남수학회 2021 호남수학학술지 Vol.43 No.4

The aim of the present work is to study the properties of three-dimensional Lorentzian para-Kenmotsu manifolds equipped with a Yamabe soliton. It is proved that every three-dimensional Lorentzian para-Kenmotsu manifold is Ricci semi-symmetric if and only if it is Einstein. Also, if the metric of a three-dimensional semi-symmetric Lorentzian para-Kenmotsu manifold is a Yamabe soliton, then the soliton is shrinking and the flow vector field is Killing. We also study the properties of threedimensional Ricci symmetric and η-parallel Lorentzian para-Kenmotsu manifolds with Yamabe solitons. Finally, we give a non-trivial example of three-dimensional Lorentzian para-Kenmotsu manifold.

Optimized deep neural network models for blood pressure classification using Fourier analysis‑based time–frequency spectrogram of photoplethysmography signal

Pankaj,Ashish Kumar,Manjeet Kumar,Rama Komaragiri 대한의용생체공학회 2023 Biomedical Engineering Letters (BMEL) Vol.13 No.4

Appropriate blood pressure (BP) management through continuous monitoring and rapid diagnosis helps to take preventivecare against cardiovascular diseases (CVD). As hypertension is one of the leading causes of CVDs, keeping hypertensionunder control by a timely screening of subjects becomes lifesaving. This work proposes estimating BP from motion artifactaffectedphotoplethysmography signals (PPG) by applying signal processing techniques in realtime. This paper proposes adeep neural network-based methodology to accurately classify PPG signals using a Fourier theory-based time–frequency(TF) spectrogram. This work uses the Fourier decomposition method (FDM) to transform a PPG signal into a TF spectrogram. In the proposed work, the last three layers of the pre-trained deep neural network, namely, GoogleNet, DenseNet, andAlexNet, are modified and then used to classify the PPG signal into normotension, pre-hypertension, and hypertension. Theproposed framework is trained and tested using the MIMIC-III and PPG–BP databases using five-fold training and testing. Out of the three deep neural networks, the proposed framework with the DenseNet-201 network performs best, with a testaccuracy of 96.5%. The proposed work uses FDM to compute the TF spectrogram to accurately separate the motion artifactsand noise components from a noise-corrupted PPG signal. Capturing more frequency components that contain moreinformation from PPG signals makes the deep neural networks extract better and more meaningful features. Thus, training adeep neural network model with clean PPG signal features improves the generalized capability of a BP classification modelwhen tested in realtime.

Morphological and electro-optical responses of dichroic polymer dispersed liquid crystal films

Pankaj Kumar,K.K. Raina 한국물리학회 2007 Current Applied Physics Vol.7 No.6

polymerization induced phase separation technique using nematic liquid crystal material in UV curable polymer NOA 65 and anthra-quinone dichroic dye. The eects of applied voltage and temperature on the LC droplet morphology and its optical characteristics werestudied in detail. Liquid crystal droplets containing low concentration of dye (6 0.25%) in polymer matrix exhibit bipolar conguration atlower applied voltage (6 10 V) whereas at relatively higher voltage (Plow concentration DPDLC lm shows better optical transmission and higher contrast ratio.

6세기 신라에서의 아소카상징(Asokan Symbolism)의 수용과 그 의의

( Pankaj Mohan ) 한국사상사학회 2004 韓國思想史學 Vol.0 No.23

Experimental and Numerical Analysis of Mechanical, Thermal and Thermomechanical Properties of Hybrid Glass/Metal Fiber Reinforced Epoxy Composites

Pankaj Agarwal,Mukesh Kumar,Mahavir Choudhary,Ankush Sharma,Amar Patnaik 한국섬유공학회 2022 Fibers and polymers Vol.23 No.5

This work clearly demonstrates the effective utilization of industrial waste metal fiber to replace glass fiber loadingfor the development of hybrid glass/metal fiber reinforced polymer composites for marine applications. The presentcomposite is fabricated by vacuum assisted resin transfer modelling technique under controlled conditions by varying bothglass fiber and metal fiber in a desired percentage weight ratio. The fabricated hybrid composites are characterized byphysical (density and void content), mechanical (tensile strength, flexural strength, inter-laminar shear strength and impactstrength), thermomechanical analysis (storage modulus, loss modulus and damping factor), water absorption, thermalconductivity and thermo-gravimetric analysis respectively. The second part of this study mainly covers the simulationanalysis of both mechanical properties and the thermal conductivity of the hybrid polymer composites. This analysis mainlyhelps to understand the major causes affecting during experimental analysis along with finding the desired results bycomparing them with the experimental results. The last part of this analysis focuses on studying the composite defects duringmechanical characterization with the help of scanning electron microscope. Finally, adopted multicriteria decision-makingtechnique to optimize the process parameters by considering all the obtained experimental results to satisfy the proposedapplication specifically can be used for marine structure development.

Beyond the “Nation-Protecting” Paradigm : Recent Trends in the Historical Studies of Korean Buddhism

Pankaj N. Mohan The Academy of Korean Studies 2006 THE REVIEW OF KOREAN STUDIES Vol.9 No.1

Large Amplitude Hygrothermal Dependent Frequency and Post-Buckling Behaviour of Smart Skew Sandwich Shell Panels -A Macromechanical FE Approach

Pankaj V. Katariya,Subrata Kumar Panda,Chetan Kumar Hirwani 한국섬유공학회 2022 Fibers and polymers Vol.23 No.11

The large geometrical distortion effect on the skew sandwich panel and improvement of the eigenvalue responsesdue to the embedded functional material (shape memory alloy, SMA) is investigated for the first time in this research. Thestructural responses are numerically predicted via a macro-mechanical nonlinear finite element model with the alternatingelastic constants due to the change in environmental conditions. The nonlinear formulation is derived mathematically viathird-order deformation kinematics including the through-thickness elongations. Moreover, the large geometrical shapechanges of the skew sandwich shell panels are described by Green-Lagrange strain whereas the material nonlinearity due tothe functional fibre inclusion modelled through the step-wise temperature-dependent properties of the individual panelconstituents (face skins, core and SMA fibre). The proposed macro-mechanical material model is helping to evaluate thecomposite sandwich properties due to the variation of hygrothermal environment. The eigenvalue type of system equation isderived through variation principle with and without excess geometrical alteration and solved via the robust Picard’s iterationtechnique in association with nonlinear finite element steps. The marching technique is adopted to include the materialnonlinearity within the mathematical model to include the variation of SMA elastic properties (volume fraction, pre-strainand blocking stress). The viability of the proposed model to compute the responses are tested by checking a few examplesconsidering the curvature parameter, layer sequence, SMA layer and the environmental changes. Additionally, it is extendedto figure out the influences of individual and combined cases of parameters on the nonlinear frequency and bucklingcharacteristics of SMA bonded sandwich shell panel with and without skew angle.

Maximum power point tracking using adjustable gain based model reference adaptive control

Pankaj Sahu,Rajiv Dey 전력전자학회 2022 JOURNAL OF POWER ELECTRONICS Vol.22 No.1

This paper aims to develop an adjustable gain-based model reference adaptive control (AG-MRAC) scheme for maximum power point tracking (MPPT) in photovoltaic (PV) systems. To ensure a fast convergence speed with guaranteed transient performance and overall system stability of the MPPT under rapidly changing environmental conditions, a 2-level control scheme has been proposed. The first level of control is the conventional ripple correlation control (RCC), which is used to obtain a ripple-free optimal duty cycle in the steady-state. This also serves as input for the second level of control, which is the proposed AG-MRAC controller. The conventional high-static adaptation gain MRAC provides guaranteed transient performance in MPPT. However, a high adaptation gain circumvents the adverse effects on the system stability and robustness. Moreover, in PV systems, when the environmental conditions are rapidly changing, the requirement gain depends on the magnitude of the error. Therefore, a fixed high gain controller does not provide a complete solution to the dynamic behavior of non-linear PV systems under rapidly changing environmental conditions. This paper attempts to overcome these issues using the proposed AG-MRAC architecture, where the adaptation gain is adjusted as a function of the tracking error, which is caused by variations in environmental conditions. A mathematical model of the proposed AG-MRAC has been developed and its stability has been verified using Lyapunov theory. To check the effectiveness of the proposed control scheme, simulation and experimental models have been developed for validation. In addition, a performance comparison has been done with recent similar works.

Special Lecture : Neuronal Stem Cells For Treatment of Gastrointestinal Dysmotility

( Pankaj Jay Pasricha ) 대한소화관운동학회 2006 대한소화관운동학회 춘계학술대회 Vol.2006 No.-

Cavitating Turbulent Flow Study for Low Head Francis Turbine by Transient Analysis

Pankaj P Gohil,R P Saini 한국유체기계학회 2019 International journal of fluid machinery and syste Vol.12 No.1

Cavitation is undesirable phenomenon and it is difficult to eliminate completely, however it is minimized to the acceptable limits. It becomes more severe under off-design conditions and lower tail race level. Shear Stress Transport (SST) turbulence model and Rayleigh-Plesset mass transfer models are used using CFX solver for performing the transient simulation and investigating the cavitation turbulent flow through Francis turbine. An attempt has been carried out to analysis of cavitating flow at low head Francis turbine under different operating conditions having varying suction heads. Experimentation has been carried out to validate the simulation results. It was found that obtained simulation results are very close agreement with experimental results. Summarizing, the performance loss and cavitation rate are found maximum under over load operating conditions. At part load operating conditions of the turbine, high amplitude of pressure at low frequency has been found which may cause fatigue damage to the turbine over time. Cavitation rate, performance loss and magnitude of pressure pulsation increase with increase of suction head.