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INFLUENCE OF RIGID BOUNDARY ON THE LOVE WAVE PROPAGATION IN ELASTIC LAYER WITH VOID PORES

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Acta Mechanica Solida Sinica 2013年第5期26卷 551-558页

作者： Sumit kumar Vishwakarma Shishir gupta Dinesh kumar Majhi Department of Applied Mathematics Indian School of Mines Department of Mathematics Birla Institute of Technology and Science

In this paper, a mathematical model for Love wave propagation in a porous elastic layer under a rigid boundary resting over a poro-elastic half-space has been developed. The study shows that such a medium transmits two types of Love waves. The first front depends on the change in volume fraction of the pores whereas the second front depends upon the modulus of rigidity of the elastic matrix of the medium and is the same as the Love wave in an elastic layer over an elastic half-space. It is observed that the first front is many times faster than the shear wave in the medium with void pores due to the change in the volume fraction of the pores and is significant.

关键词： Love waves void pores volume fraction rigid boundary wave front

Performance evaluation of cement-stabilized pond ash-rice husk ashclay mixture as a highway construction material

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Journal of Rock Mechanics and Geotechnical Engineering 2017年第1期9卷 159-169页

作者： Deepak gupta Arvind kumar Department of Civil Engineering National Institute of Technology (NIT) Jalandhar India

This paper reports the results of an investigation carried out on clay soil stabilized with pond ash(PA),rice husk ash(RHA) and cement. Modified Proctor compaction tests were performed in order to investigate the compaction behavior of clay, and California bearing ratio(CBR) tests were performed to determine the strength characteristics of clay. For evaluation purpose, the specimens containing different amounts of admixtures were prepared. Clay was replaced with PA and RHA at a dosage of 30%e45% and5%e20%, respectively. The influence of stabilizer types and dosages on mechanical properties of clay was evaluated. In order to study the surface morphology and crystallization characteristics of the soil samples, scanning electron microscopy(SEM) and X-ray diffraction(XRD) analyses were carried out,respectively. The results obtained indicated a decrease in the maximum dry density(MDD) and a simultaneous increase in the optimum moisture content(OMC) with the addition of PA and *** linear regression analysis(MLRA) showed that the predicted values of CBR tests are in good agreement with the experimental values. Developed stabilized soil mixtures showed satisfactory strength and can be used for construction of embankments and stabilization of sub-grade soil. The use of locally available soils, PA, RHA, and cement in the production of stabilized soils for such applications can provide sustainability for the local construction industry.

关键词： California bearing ratio(CBR) Pond ash(PA) Rice husk ash(RHA) Optimum moisture content(OMC) Maximum dry density(MDD)

Electrical conductivity of Gd doped BiFeO3-PbZrO3 composite

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Frontiers of Materials Science 2013年第3期7卷 295-301页

作者： santosh kumar SATPATHY Nilaya kumar MOHANTY Ajay kumar BEHERA Banarji BEHERA Pratibindhya NAYAK Materials Research Laboratory School of Physics Sambalpur University Jyoti Vihar Burla-768019 Odisha India

The composite, 0.5（BiGd0.15Fe0.85O3）-0.5（PbZrO3）, was synthesized using the solid-state reaction technique. The formation of the compound was confirmed by XRD with an orthorhombic structure at room temperature. The impedance parameters were studied using an impedance analyzer in a wide range of frequency （10z-106Hz） at different temperatures. The Nyquist plot suggests the contribution of bulk effect and a slight indication of grain boundary effect and the bulk resistance decreases with a rise in temperature. The presence of temperature-dependent relaxation process occurs in the material. Electrical modulus reveals the presence of the hopping mechanism in the materials. The value of exponent n, pre-factor A and adc were obtained by fitting ac conductivity data with Jonscher＇s universal power law. The activation energies calculated from the ac conductivity were found to be 0.50, 0.46, 0.44, 0.43, 0.42 and 0.38 eV at 1, 10, 50, 100, 500 kHz and I MHz respectively in the temperature region of 110℃-350℃. The dc conductivity was found to increase with the rise in temperature. The activation energy calculated from complex impedance plot and from the fitted Jonscher＇s power law are very close, which results similar type of charge carrier exist in conduction mechanism of the material.

关键词： solid state reaction XRD impedance electrical conductivity

Diagnosis and Detection of Alzheimer’s Disease Using Learning Algorithm

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Big Data Mining and Analytics 2023年第4期6卷 504-512页

作者： Gargi Pant Shukla santosh kumar Saroj kumar Pandey Rohit Agarwal Neeraj Varshney Ankit kumar the Department of Management Doon Business SchoolDehradun 248001India. Jaipuria Institute of Management Jaipur 302033India Department of Computer Engineering and Apllications GLA UniversityMathura 281406India.

In Computer-Aided Detection(CAD)brain disease classification is a vital ***’s Disease(AD)and brain tumors are the primary reasons of *** studies of these diseases are carried out by Magnetic Resonance Imaging(MRI),Positron Emission Tomography(PET),and Computed Tomography(CT)scans which require expertise to understand the *** disease is the most prevalent in the elderly and can be fatal in its later *** result can be determined by calculating the mini-mental state exam score,following which the MRI scan of the brain is *** from that,various classification algorithms,such as machine learning and deep learning,are useful for diagnosing MRI ***,they do have some limitations in terms of *** paper proposes some insightful pre-processing methods that significantly improve the classification performance of these MRI ***,it reduced the time it took to train the model of various pre-existing learning algorithms.A dataset was obtained from Alzheimer’s Disease Neurological Initiative(ADNI)and converted from a 4D format to a 2D *** clipping,grayscale image conversion,and histogram equalization techniques were used to pre-process the *** pre-processing,we proposed three learning algorithms for AD classification,that is random forest,XGBoost,and Convolution Neural Networks(CNN).Results are computed on dataset and show that it outperformed with exiting work in terms of accuracy is 97.57%and sensitivity is 97.60%.

关键词： alzheimer’s disease deep learning random forest XGBoost

Pullout of soil nail with circular discs: A three-dimensional finite element analysis

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Journal of Rock Mechanics and Geotechnical Engineering 2017年第5期9卷 967-980页

作者： Saurabh Rawat Ashok kumar gupta Anil kumar Department of Civil Engineering Jaypee University of Information Technology Waknaghat Solan 173234 Himachal Pradesh India

An internal failure mode for a soil-nailed system consists of failure at nail heads,slope facing,nail strength,along groutesoil interface and pullout failure.A better understanding of pullout of soil nail thus becomes important to assess the stability of a soil-nailed *** the present study,an investigation into the pullout behaviour of soil nail with circular discs along the shaft has been carried out by a threedimensional finite element analysis using Abaqus/Explicit routine.A total of 67 simulations have been performed to accurately predict the pullout behaviour of soil *** soil nail under study has circular discs along its shaft varying in numbers from 1 to *** pullout of this soil nail in a pullout test box has been simulated with a constant overburden pressure of 20 kPa acting on the *** pullout load edisplacement characteristics,stresses around soil nail and failure mechanism during pullout are *** of dimensionless factors such as normalised pullout load factor and bearing capacity factor have been obtained with different combinations of parameters in terms of relative disc spacing ratio,anchorage length ratio,embedment ratio,diameter ratio and displacement *** the results of analyses,it is found that nail with more circular discs requires higher pullout *** are critical relative disc spacing ratio and diameter ratio which significantly affect the pullout behaviour of nail.

关键词： Pullout behaviour Finite element analysis Soil nail Circular discs Dimensionless factors

CFD modeling to study the effect of particle size on dispersion in 20l explosion chamber: An overview

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International Journal of Mining Science and Technology 2020年第3期30卷 321-327页

作者： santosh kumar Ray Niroj kumar Mohalik Asfar Mobin Khan Debashish Mishra Nikhil kumar Varma Jai Krishna Pandey Pradeep kumar Singh CSIR-Central Institute of Mining and Fuel Research Dhanbad 826001India

Mine disasters occur predominantly due to methane or coal dust explosion or a combination of *** the top ten worst coal mine disasters in India, nine are due to coal dust explosion. The current paper describes a general overview of the parameters causing dispersion leading to coal dust explosion,and computational fluid dynamics(CFD) simulation study to observe the effects of particle size on dispersion in Indian coal mines. Turbulent kinetic energy(TKE) and velocity vector path of dust-air mixture and dust-free air were simulated to understand their effects on coal dust dispersion. The TKE contours and velocity vector paths for dust-free air were uniform and symmetrical due to resistance-free path available. The TKE contours and velocity vector paths for dust-air mixture shows the asymmetrical distribution of contours, due to entrainment of air with dust particles. Vortices were observed in velocity vector paths which gradually diminish on increment of time sequence. These vortices are dead centres where velocity and coal dust particles concentration are both zero.

关键词： Coal dust explosibility CFD 20l explosion chamber Dispersion Turbulent kinetic energy

Off-Pump Coronary Artery Bypass Grafting in Patients with Left Ventricular Dysfunction: Short-Term Results from a Single Center in Bangladesh

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World Journal of Cardiovascular Surgery 2024年第9期14卷 145-156页

作者： Muhit Abdullah Md. Abir Tazim Chowdhury Satyajit Sharma Rehana Akther Munama Magdum Munjerin Refat Synthee Md. Zafar-Al-Nimari Saikat Das gupta Saleh Ahmed Samir kumar Biswas M. Quamrul Islam Talukder Farooque Ahmed Department of Cardiac Surgery National Heart Foundation Hospital and Research Institute (NHFH&RI) Dhaka Bangladesh Department of Cardiothoracic and Vascular Surgery Evercare Hospital Dhaka Dhaka Bangladesh Ispahani Islamia Eye Institute & Hospital Khamarbari Dhaka Bangladesh National Institute of Preventive and Social Medicine Dhaka Bangladesh Square Hospital Dhaka Bangladesh

Background: Off-pump coronary artery bypass grafting (OPCAB) is considered a safer alternative to on-pump surgery, especially in patients with left ventricular dysfunction (LVD). Objectives: This study assessed short-term outcomes and functional improvements in LVD patients post-OPCAB. Methods: The study included 200 coronary artery disease patients who underwent isolated off-pump coronary artery bypass grafting (OPCAB) at the National Heart Foundation Hospital and Research Institute between January 2019 and June 2020. Patients were categorized into Group 1, with a left ventricular ejection fraction (LVEF) of 30% - 39%, and Group 2, with an LVEF of 40% or higher. Echocardiographic assessments of left ventricular dimensions and ejection fraction were performed preoperatively, at discharge, and one month postoperatively. Results: In Group 1, preoperative left ventricular internal dimensions during diastole (LVIDd) and systole (LVIDs) were 53.48 ± 4.40 mm and 44.23 ± 3.93 mm, respectively, with a left ventricular ejection fraction (LVEF) of 35.28% ± 2.26%. At discharge, these values improved to 51.58 ± 4.04 mm (LVIDd), 41.23 ± 5.30 mm (LVIDs), and 39.25% ± 3.75% (LVEF). One month postoperatively, further improvements were observed: 46.29 ± 3.76 mm (LVIDd), 37.45 ± 3.68 mm (LVIDs), and 43.22% ± 4.67% (LVEF). Group 2 showed similar positive outcomes, with preoperative values of 47.09 ± 5.06 mm (LVIDd), 35.11 ± 5.25 mm (LVIDs), and 50.13% ± 7.25% (LVEF), improving to 42.37 ± 4.18 mm (LVIDd), 31.05 ± 4.19 mm (LVIDs), and 55.33% ± 7.05% (LVEF) at one month postoperatively. Both groups demonstrated significant improvements in left ventricular function and NYHA class, with most patients moving from class III/IV to I/II. Complications were minimal, and no mortality was observed. Conclusion: OPCAB is safe and effective for patients with LVEF 30% - 39% and LVEF ≥ 40%, providing significant short-term functional improvements without increased risk.

关键词： Off-Pump Coronary Artery Bypass Grafting Left Ventricular Dysfunction (LVD) Short-Term Outcomes

Prediction of COVID-19 Confirmed, Death, and Cured Cases in India Using Random Forest Model

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Big Data Mining and Analytics 2021年第2期4卷 116-123页

作者： Vishan kumar gupta Avdhesh gupta Dinesh kumar Anjali Sardana Department of Computer Science and Engineering(CSE) Graphic Era Deemed to be UniversityDehradun 248002India Department of CSE IMS Engineering CollegeGhaziabad 201009India Department of CSE KIET Group of InstitutionsGhaziabad 201206India

A novel coronavirus(SARS-CoV-2) is an unusual viral pneumonia in patients, first found in late December 2019, latter it declared a pandemic by World Health Organizations because of its fatal effects on public health. In this present, cases of COVID-19 pandemic are exponentially increasing day by day in the whole world. Here, we are detecting the COVID-19 cases, i.e., confirmed, death, and cured cases in India only. We are performing this analysis based on the cases occurring in different states of India in chronological dates. Our dataset contains multiple classes so we are performing multi-class classification. On this dataset, first, we performed data cleansing and feature selection, then performed forecasting of all classes using random forest, linear model, support vector machine,decision tree, and neural network, where random forest model outperformed the others, therefore, the random forest is used for prediction and analysis of all the results. The K-fold cross-validation is performed to measure the consistency of the model.

关键词： coronavirus COVID-19 respiratory tract multi-class classification random forest

Numerical modelling of pullout of helical soil nail

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Journal of Rock Mechanics and Geotechnical Engineering 2017年第4期9卷 648-658页

作者： Saurabh Rawat Ashok kumar gupta Department of Civil Engineering Jaypee University of Information Technology Waknaghat Solan 173234 India

An investigation into the pullout response of helical soil nail using finite element subroutine Plaxis 2D is *** numerical modelling of actual pullout response is achieved by axisymmetric and horizontal loading *** effect of varying number of helical plates,helical plate spacing and helical plate diameter is studied to understand the pullout capacity *** failure surfaces for various helical soil nail configurations and their pullout mechanisms are also analysed and *** pullout capacity is found to increase with increase in number of helical *** helical plate spacing ratio（s/D;） and diameter ratio（D;/D;） are found to increase the pullout only up to a critical *** response of helical soil nail using axisymmetric finite element simulation is found similar to the uplift behaviour of helical piles and helical soil *** the absence of literature regarding numerical modelling of helical soil nail,simulation results are validated with uplift responses of helical piles and soil anchors.A good agreement in their comparative study for pullout response is also observed.

关键词： Finite element Helical soil nail Pullout response Plate spacing Plate diameter Failure mechanism