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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

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

Recent advances in catalytic combustion of AP-based composite solid propellants

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Defence Technology（防务技术） 2021年第3期17卷 1013-1031页

作者： narendra Yadav Prem kumar Srivastava mohan Varma Department of Space Engineering&Rocketry India Department of Chemistry Birla Institute of TechnologyMesraRanchiIndia

Composite solid propellants(CSPs) have widely been used as main energy source for propelling the rockets in both space and military applications. Internal ballistic parameters of rockets like characteristic exhaust velocity, specific impulse, thrust, burning rate etc., are measured to assess and control the performance of rocket motors. The burn rate of solid propellants has been considered as most vital parameter for design of solid rocket motors to meet specific mission requirements. The burning rate of solid propellants can be tailored by using different constituents, extent of oxidizer loading and its particle size and more commonly by incorporating suitable combustion catalysts. Various metal oxides(mOs),complexes, metal powders and metal alloys have shown positive catalytic behaviour during the combustion of CSPs. These are usually solid-state catalysts that play multiple roles in combustion of CSPs such as reduction in activation energy, enhancement of rate of reaction, modification of sequences in reaction-phase, influence on condensed-phase combustion and participation in combustion process in gas-phase reactions. The application of nanoscale catalysts in CSPs has increased considerably in recent past due to their superior catalytic properties as compared to their bulk-sized counterparts. A large surface-to-volume ratio and quantum size effect of nanocatalysts are considered to be plausible reasons for improving the combustion characteristics of propellants. Several efforts have been made to produce nanoscale combustion catalysts for advanced propellant formulations to improve their energetics. The work done so far is largely scattered. In this review, an effort has been made to introduce various combustion catalysts having at least a metallic entity. Recent developments of nanoscale combustion catalysts with their specific merits are discussed. The combustion chemistry of a typical CSP is briefly discussed for providing a better understanding on role of co

关键词： Composite solid propellants Burn rate modifier metallic nano-catalysts Catalytic combustion Thermal decomposition

Translocator protein and neurodegeneration: insights from Alzheimer’s disease

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Neural Regeneration Research 2025年第4期20卷 1090-1091页

作者： Arpit kumar Pradhan Rainer Rupprecht Gerhard Rammes Klinik für Anaesthesiologie und Intensivmedizin der Technischen Universität münchen Klinikum rechts der IsarMunichGermany Graduate School of Systemic Neurosciences Ludwig-Maximilians-Universität MünchenMartinsriedGermany Department of Psychiatry and Psychotherapy University RegensburgRegensburgGermany

The 18 kDa translocator protein(TSPO)located on the outer mitochondrial membrane regulates several key cellular processes including mitochondrial homeostasis,cholesterol transport,apoptosis,cell proliferation,and maintenance of mitochondrial health(Rupprecht et al.,2022,2023).TSPO is expressed in both peripheral organs and the central nervous system,with a more pronounced expression in tissues that produce *** main reason why TSPO has garnered so much attention is because it plays a key role in neurosteroidogenesis by transferring cholesterol from the outer to the inner mitochondrial membrane,which is the rate-limiting step in neurosteroid synthesis.A cholesterol-recognizing amino acid consensus domain has been identified in the cytosolic C terminus of the TSPO protein by both in vitro and site-directed mutagenesis experiments(Li et al.,2001).However,the role of TSPO in the process of neurosteroid synthesis has been challenged by several studies,particularly TSPO knockout models,which suggest that TSPO removal does not affect the phenotype or the system’s viability(Tu et al.,2014).However,ligands targeting TSPO have been shown to enhance levels of neurosteroids which suggests that neurosteroidogenesis is one of the major functional roles mediated by the TSPO protein.

关键词： cholesterol organs

DNA computing over the ring Z4[v]/(v^2-v)

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International Journal of Biomathematics 2018年第7期11卷 149-166页

作者： narendra kumar Abhay kumar Singh Department of Applied mathematics Indian Institute of Technology (ISm) Dhanbad Jharkhand 826004India

In this paper,we discuss the DNA construction of general length over the finite ring =Z4+vZ4,with v2=v,which plays a very significant role in DNA *** discuss the GC weight of DNA codes over *** examples of reversible ... 详细信息

关键词： Cyclic codes DNA codes GC weight

macular microvascular and structural changes on optical coherence tomography angiography in atypical optic neuritis

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World Journal of methodology 2025年第1期15卷 88-94页

作者： Chinmay mahatme madhurima Kaushik Veerappan Rathinasabapathy Saravanan Karthik kumar Virna m Shah Department of General Ophthalmology Aravind Eye HospitalCoimbatore 641014Tamil NāduIndia Department of Neuro-ophthalmology Aravind Eye HospitalCoimbatore 641014Tamil NāduIndia Department of Vitreoretina Aravind Eye HospitalCoimbatore 641014Tamil NāduIndia

BACKGROUND Atypical optic neuritis,consisting of neuromyelitis optica spectrum disorders(NmOSD)or myelin oligodendrocyte glycoprotein antibody disease(mOGAD),has a very similar presentation but different prognostic implications and longterm management *** and metabolic factors are being thought to play a role in such autoimmune neuro-inflammatory disorders,apart from the obvious immune mediated *** the advent of optical coherence tomography angiography(OCTA),it is easy to pick up on these subclinical macular microvascular and structural *** To study the macular microvascular and structural changes on OCTA in atypical optic *** This observational cross-sectional study involved 8 NmOSD and 17 mOGAD patients,diagnosed serologically,as well as 10 healthy *** vascular density(mVD)and ganglion cell+inner plexiform layer thickness(GCIPL)were studied using *** There was a significant reduction in mVD in NmOSD and mOGAD affected as well as unaffected eyes when compared with healthy *** and mOGAD affected eyes had significant GCIPL thinning compared with healthy *** unaffected eyes did not show significant GCIPL thinning compared to healthy controls in contrast to mOGAD unaffected *** comparing NmOSD with mOGAD,there was no significant difference in terms of mVD or GCIPL in the affected or unaffected *** Although significant microvascular and structural changes are present on OCTA between atypical optic neuritis and normal patients,they could not help in differentiating between NmOSD and mOGAD cases.

关键词： Optical coherence tomography angiography Atypical optic neuritis macular microvascular changes Neuromyelitis optica spectrum disorders myelin oligodendrocyte glycoprotein antibody disorder

CFD analysis of performance improvement of the Savonius water turbine by using an impinging jet duct design

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Chinese Journal of Chemical Engineering 2019年第4期27卷 794-801页

作者： narendra Thakur Agnimitra Biswas Yogesh kumar mithinga Basumatary mechanical Engg.Deptt. NIT Silchar

The majority of research on water turbines focuses on design improvement of large-scale hydrokinetic turbines for power generation, which may have delayed the utilization of kinetic energy contained in rivers and canals. The aim of this paper is to improve the efficiency of a two bladed Savonius type cross-flow hydrokinetic turbine, which can be used as an energy converter to harness free-stream kinetic energy of water. An impinging jet duct design is presented for improving performance of the Savonius turbine in wind application as seen from literature. The performance of the modified turbine is evaluated using CFD software Fluent, and is compared with that of a simple two bladed Savonius water turbine and some of the prominent literature designs of the Savonius turbine. It is shown that the present design exhibits improved performance compared to the selected designs of the Savonius *** an insight of the improved performance of the modified turbine is also obtained from flow physics study.

关键词： Savonius water turbine CFD Impinging jet duct design Power coefficient Water power Flow physics

Real Time Automation and Ratio Control Using PLC&SCADA in Industry 4.0

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Computer Systems Science & Engineering 2023年第5期45卷 1495-1516页

作者： Basant Tomar narendra kumar mini Sreejeth Dept of Electrical Engineering Delhi Technological UniversityDelhi 110042India

Industrial Control Systems(ICS)and SCADA(Supervisory Control and Data Acquisition)systems play a critical role in the management and regulation of critical *** systems brings us closer to the real-time application *** process and equipment control capability is typically provided by a Distributed Control System(DCS)in industries such as power stations,agricultural systems,chemical and water treatment *** of control through DCS,this paper proposes a SCADA and PLC(Programmable Logic Controller)system to control the ratio control division and the assembly line division inside the chemical plant.A specific design and implementation method for development of SCADA/PLC based real time ratio control and automated assembly line system in a chemical plant is *** assembly line division is further divided into sorting stage,filling stage and the auxiliary stage,which includes the capping unit,labelling unit and then the *** the ratio control division,we have defined the levels inside the mixer and ratio of the raw materials through human machine interface(HmI)*** ratio of raw materials is kept constant on the basis of flow rates of wild stream and manipulated *** is a flexibility in defining new levels and the ratios of the raw materials inside the *** here we taken the predefined levels(low,medium,high)and ratios(3:4,2:1,2:5).Control valves are used for regulating the flow of the *** the assembly line division,the containers are sorted on the basis of size and type of material used i.e.,big sized metallic containers and small sized non-metallic containers by inductive and capacitive proximity *** the processes are facilitated with laser beam type or reflective type sensors on the conveyor *** a highly stable and dependable PLC/SCADA system instead of Distributed Control System is required to achieve automatic management and control of chemical industry processes to reduce

关键词： Industry 4.0 ratio control automation PLC SCADA control valves proximity sensors conveyor system solenoid valves