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A SUSPENSION MODEL FOR BLOOD FLOW THROUGH A CATHETERIZED ARTERY

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International Journal of Biomathematics 2012年第5期5卷 21-35页

作者： SHAILESH MISHRA narendra kumar verma S. U. SIDDIQUI Department of MathematicsHarcourt Butler Technological Institute Kanpur-208002 India

The present work is concerned with the analysis of an axi-symmetric flow of blood through coaxial tubes where the outer tube has an axially symmetric mild stenosis and the inner tube has a balloon which is axi-symmetric in nature. The mild stenosis approximation is used to solve the present problem. The effect of the volume fraction density of the particles, the maximum height attained by the balloon, the radius of the inner tube, which keeps the balloon in position k, and the axial displacement of the balloon have been studied. Flow parameters such as the resistive impedance, the wall shear stress distribution in the stenotic region and its magnitude at the stenosis throat have been computed for different parameters. It is observed that the resistance to flow decreases with increasing values of the axial displacement of the balloon, while the resistance to flow increases with the volume fraction density of the particles, the radius of the inner tube, which keeps the balloon in position k, and the maximum height attained by the balloon. The wall shear stress distribution in the stenotic region possesses a character similar to the resistance to flow with respect to any parameter.

关键词： Blood now stenosis resistive impedance wall shear stress suspension.

Effect of Slip Velocity on Blood Flow through a Catheterized Artery

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Applied Mathematics 2011年第6期2卷 764-770页

作者： narendra kumar verma Shailesh Mishra Shafi Ullah Siddiqui Ram Saran Gupta 不详

A mathematical model for pulsatile flow of blood in a catheterized artery in presence of an axisymmetric stenosis with a velocity slip at the constricted wall is proposed. The expressions for the flow characteristics, velocity profiles, the flow resistance, the wall shear stress, the effective viscosity are obtained in the present analysis. The effects of slip velocity on the blood flow characteristics are shown graphically and discussed briefly.

关键词： Pulsatile Stenosis Catheter Flow Resistance Wall Shear Stress Slip Velocity

Battery energy storage-based system damping controller for alleviating sub-synchronous oscillations in a DFIG-based wind power plant

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Protection and Control of Modern Power Systems 2023年第2期8卷 260-277页

作者： Neevatika verma narendra kumar Rajeev kumar Department of Electrical Engineering Delhi Technological UniversityNew DelhiIndia Electrical Engineering Department Jamia Millia IslamiaNew DelhiIndia Electrical and Electronics Engineering Department KIET Group of InstitutionsGhaziabadIndia

This paper presents the issue of the Sub-synchronous resonance(SSR)phenomenon in a series compensated DFIG-based wind power plant and its alleviation using a Battery Energy Storage-based Damping Controller(BESSDCL).A supplementary damping signal is developed considering the angular speed deviation and is incorporated into the BESS control ***-area Measurement System data is used to determine the angular speed deviation.A lin-earized system model is developed to perform eigenvalue analysis,and to detect and examine unstable SSR *** variation of wind speed and three-phase fault are also taken into consideration to validate the robustness of the *** further verify the efficacy of the proposed damping controller,time-domain simulations are performed using MATLAB/*** application of the proposed BESSDCL stabilizes all the unstable system modes effectively at wind speeds of 7 m/s,9 m/s,and 11 m/s,and at 40%,50%,and 60%series compensation levels,as well three-phase fault conditions.

关键词： Battery energy storage system Damping controller Doubly-fed induction generator(DFIG) Series

Review of sub-synchronous interaction in wind integrated power systems: classification, challenges, and mitigation techniques

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Protection and Control of Modern Power Systems 2023年第2期8卷 13-38页

作者： Neevatika verma narendra kumar Saket Gupta Hasmat Malik Fausto Pedro García Márquez Department of Electrical Engineering Delhi Technological UniversityDelhi 110042India Department of Electrical Power Engineering Faculty of Electrical EngineeringUniversiti Teknologi Malaysia(UTM)81310 JohorMalaysia Ingenium Research Group DepartmentUniversidad Castilla-La Mancha13071 Ciudad RealSpain Department of Electrical Engineering Graphic Era Deemed to be UniversityDehradun 248002India Instrumentation and Control Engineering Department Bharati Vidyapeeth’s College of EngineeringNew Delhi 110056India

Emerging sub-synchronous interactions(SSI)in wind-integrated power systems have added intense attention after numerous incidents in the US and China due to the involvement of series compensated transmission lines and power electronics *** phenomenon occurs when two power system elements exchange energy below the synchro-nous *** phenomenon related to wind power plants is one of the most significant challenges to main-taining stability,while SSI phenomenon in practical wind farms,which has been observed recently,has not yet been described on the source of conventional SSI *** paper first explains the traditional development of SSI and its classification as given by the IEEE,and then it proposes a classification of SSI according to the current research status,reviews several mitigation techniques and challenges,and discusses analysis techniques for *** paper also describes the effect of the active damping controllers,control scheme parameters,degree of series compensation,and various techniques used in wind power plants(WPPs).In particular,a supplementary damping controller with converter controllers in Doubly Fed Induction Generator based WPPs is briefly *** paper provides a real-istic viewpoint and a potential outlook for the readers to properly deal with SSI and its mitigation techniques,which can help power engineers for the planning,economical operation,and future expansion of sustainable development.

关键词： Damping controller Doubly fed induction generator(DFIG) Series compensations Sub-synchronous interactions(SSI) Sub-synchronous resonance(SSR)

Event-Triggered Sliding Mode Control for Trajectory Tracking of Nonlinear Systems

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IEEE/CAA Journal of Automatica Sinica 2020年第1期7卷 307-314页

作者： Aquib Mustafa narendra K.Dhar Nishchal K verma Department of Electrical Engineering Indian Institute of Technology KanpurUP 208016India

In this paper, an event-triggered sliding mode control approach for trajectory tracking problem of nonlinear input affine system with disturbance has been proposed. A second order robotic manipulator system has been modeled into a general nonlinear input affine system. Initially, the global asymptotic stability is ensured with conventional periodic sampling approach for reference trajectory tracking. Then the proposed approach of event-triggered sliding mode control is discussed which guarantees semi-global uniform ultimate boundedness. The proposed control approach guarantees non-accumulation of control updates ensuring lower bounds on inter-event triggering instants avoiding Zeno behavior in presence of the disturbance. The system shows better performance in terms of reduced control updates, ensures system stability which further guarantees optimization of resource usage and cost. The simulation results are provided for validation of proposed methodology for tracking problem by a robotic manipulator. The number of aperiodic control updates is found to be approximately 44% and 61% in the presence of constant and time-varying disturbances respectively.

关键词： Event-trigger inter execution time stability sliding mode control trajectory tracking

Experimental investigation for machinability aspects of graphene oxide/carbon fiber reinforced polymer nanocomposites and predictive modeling using hybrid approach

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Defence Technology（防务技术） 2021年第5期17卷 1671-1686页

作者： Jogendra kumar Rajesh kumar verma Department of Mechanical Engineering Madan Mohan Malaviya University of TechnologyGorakhpur273010India

This article explores the drilling behavior of polymer nanocomposites reinforced by Graphene oxide/Carbon fiber using a hybrid method of Grey theory and Principal component analysis(GR-PCA).An online digital dynamometer was employed for the evaluation of Thrust Force and *** image processing technique computes the *** surface methodology(RSM)considers the parameters,namely,drilling speed(S),feed rate(F),Graphene Oxide wt.%(G)in designing the experimentation *** component analysis(PCA)was used to tackle the response priority weight during the combination of multiple *** of variance(ANOVA)scrutinized the influence of parameters and intended the regression models to predict the ***-PCA evaluated the optimal parametric setting and remarked that feed rate acts as the most predominant *** higher feed rate and wt.%of G is responsible for surface damages like fiber pull-out,fiber fracture and cracks.A significant improvement in drilling responses has been obtained and also validates through confirmatory test and microstructure investigations.

关键词： Graphene oxide Polymer Carbon fiber RSM ANOVA GR-PCA

Triaxial strength behaviour of rockmass satisfying Modified Mohr-Coulomb and Generalized Hoek-Brown criteria

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International Journal of Mining Science and Technology 2018年第6期28卷 901-915页

作者： Saurav Rukhaiyar narendra kumar Samadhiya Department of Civil Engineering Indian Institute of Technology Roorkee

The triaxial strength of twenty rockmass types was predicted using two non-linear triaxial strength criteria for rockmass i.e. Modified Mohr-Coulomb(MMC) criterion and Generalized Hoek-Brown(GHB)criterion. Four different rockmass classification systems were used for the calculation of MMC criterion parameters while only GSI classification system has been used for calculation of GHB parameters. The representative value of the uniaxial compressive strength and elastic modulus of rockmass have been estimated using probabilistic approach. A hypothetical case of an unsupported tunnel has been analyzed considering both MMC and GHB criteria. The analysis was done using the convergence-confinement method with two different approaches. The first approach predicts the tunnel response using GHB criterion directly. The second approach predicts the tunnel response using equivalent Mohr-Coulomb parameters obtained by linearization of triaxial data points obtained from MMC and GHB criteria. The tunnel response has been estimated in terms of radius of plastic zone, tunnel convergence and tunnel convergence strain. For very poor rockmasses the tunnel response predicted by MMC criterion is less than that predicted by GHB criterion. For poor and fair rockmass, the tunnel response estimated considering both the criteria are comparable except for few cases. Squeezing condition in rockmass has been also evaluated.

关键词： Triaxial strength Modified Mohr-Coulomb criterion Generalised Hoek-Brown criterion Convergence-confinement method

Strength behaviour of sandstone subjected to polyaxial state of stress

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International Journal of Mining Science and Technology 2017年第6期27卷 889-897页

作者： Rukhaiyar Saurav Samadhiya narendra kumar Department of Civil Engineering Indian Institute of Technology Roorkee Roorkee 247667 India

The paper presents an experimental investigation on the strength behaviour of natural rock subjected to polyaxial state of stress. The polyaxial tests were conducted on cubical specimens of sandstone obtained from the Shivpuri district in Madhya Pradesh state of India, The specimens having nominal dimensions of100 mm x 100 mm x 100 mm were tested using a polyaxial testing machine. Twenty-five combinations of intermediate and minor principal stresses were applied and the specimens were loaded till failure occurs. It was observed that the intermediate principal stress has a substantial effect on the strength of the Shivpuri sandstone. A database of rock strength under various combinations of σ_2 and σ_3 was obtained for the Shivpuri sandstone. The database was used to study the predictability of five most commonly used strength criterion. Root mean square error(RMSE), average absolute relative error percentage(AAREP) and coefficient of accordance(COA) were used as indices for the measure of goodness of fit. It was observed that the least error in the prediction was shown by modified Mohr Coulomb criterion followed by modified Weibols and Cook criterion. A probability analysis of the error in prediction was also done.

关键词： Polyaxial testing Sandstone Strength criterion Modified Mohr-Coulomb criterion Modified Weibols and Cook criterion

Spontaneous closure of stoma

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Gastroenterology Report 2016年第4期4卷 325-327,I0003页

作者： narendra Pandit Harjeet Singh Hemanth kumar Rajesh Gupta G.R.verma Division of Surgical Gastroenterology Department of General Surgery Post Graduate Institute of Medical Education and Research(PGIMER)ChandigarhIndia

Intestinal loop stoma is a common surgical procedure performed for various benign and malignant abdominal problems,but it rarely undergoes spontaneous closure,without surgical *** male patients presented to our emergency surgical department with acute abdominal *** of them was diagnosed as having rectosigmoid perforation and underwent diversion sigmoid loop colostomy after primary closure of the *** other was a known case of carcinoma of the rectum who had already undergone low anterior resection with covering loop ileostomy;the patient underwent second loop ileostomy,this time for complicated intestinal *** our surprise,both the loop colostomy and ileostomy closed spontaneously at 8 weeks and 6 weeks,respectively,without any *** stoma closure is a rare and interesting *** exact etiology for spontaneous closure remains unknown,but it may be hypothesized to result from slow retraction of the stoma,added to the concept of a tendency towards spontaneous closure of enterocutaneous fistula.

关键词： ileostomy colostomy spontaneous closure of stoma