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Blast Induced Damage to Surrounding Rock Mass in an Underground Excavation

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Journal of Geological Resource and Engineering 2014年第1期2卷 13-19页

作者： Harsh kumar Verma narendra kumar samadhiya Mahendra Singh Vilugundam Venkat Ramana Prasad CSIR-Central Institute of Mining and Fuel Research Roorkee 247667 India Department of Civil Engineering Indian Institute of Technology Roorkee 247667 India

Authors have conducted experiments to measure blast induced rock mass damage at L＆T-（Singoli-Bhatwari Hydro-Power Project SBHP） Rudraprayag. Repetitive NX size rock core up to 5.0 m depth were taken from side wall and face with triple tube core barrel drill. CR （core recovery） and RQD （rock quality designation） of the rock cores is computed to evaluate effect of blasting on the surrounding rock mass. RQD and CR values for the initial one meter from the line of excavation in each case reflect maximum damage due to blast. RQD for initial one meter reduced to as high as 40% of the average RQD. The rock samples were also tested using ultrasonic techniques. Ultrasonic tests on NX size core reveal that the 2.0 m of the zone surrounding the opening are adversely affected by the tunnel excavation blasting process. The ultrasonic velocities reduce to approx. 80% of the average values in the initial 0.5 m from the excavation line.

关键词： Blast induced damage ultrasonic velocity RQD and core recovery.

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

Study of Structural, Optical, Electrical and Dielectric Properties of Gd-Doped ZnO Composites Synthesized by Solid State Reaction Method

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Open Journal of Composite Materials 2024年第2期14卷 91-108页

作者： Santosh kumar Kundara Kanhaiya Chawla Dinesh kumar Yadav Chhagan Lal Balram Tripathi narendra Jakhar Department of Physics University of Rajasthan Jaipur India Sw. P.N.K.S. Government PG College Dausa India Government PG College Pratapgarh India S.S. Jain Subodh PG (Autonomous) College Jaipur India

In this manuscript, we are reporting structural, bonding, optical, dielectric, and electrical properties of Gd-doped ZnO composite samples (Zn1−xGdxO, x = 0, 0.05, 0.10) prepared by solid-state reaction method. XRD spectra confirm the wurtzite hexagonal phase with a grain size distribution of 42 - 47 nm. The FT-IR spectra confirm bonding behavior like Zn-O, O=C=O, and O-H stretching modes. FESEM micrographs show that the grains of crystallites possess nearly spherical morphology. Optical absorption spectra confirm that the optical band gap decreases systematically from 3.19 eV to 3.15 eV for x = 0.0 to x = 0.10 samples. For all samples, PL spectra exhibited near-band emission, blue emission, and green emission peaks. The dielectric constant decreases as the applied frequency increases. Hall effect results show that with increasing doping concentration of Gd, mobility and resistivity increase while bulk concentration decreases. Current-Voltage study shows that current increases when temperature is increased. Rare earth-doped ZnO is potential material used for optoelectronics and spintronics device applications. Properties of Gd-doped ZnO are studied by various research groups, but dielectric studies are limitedly reported. Therefore, the present research work aims to study the change of electrical, optical, and dielectric properties of Gd-doped ZnO for device applications.

关键词： ZnO:Gd Composites Optical Band Gap Green Emission Dielectric Constant

Assessing the role of forest resources in improving rural livelihoods in West Bengal of India

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Regional Sustainability 2024年第2期5卷 75-88页

作者： Soumen BISUI Pravat kumar SHIT Research Center for Natural and Applied Science Raja Narendra Lal Khan Women’s College(Autonomous)Vidyasagar UniversityMidnapore721102India Postgraduate Department of Geography Raja Narendra Lal Khan Women’s College(Autonomous)Vidyasagar UniversityMidnapore721102India

Forest resources play a vital role in supporting the livelihoods of rural communities residing in forest-rich *** India,a forest-rich country,a significant proportion of non-timber forest products(NTFPs)is consumed locally,supporting numerous rural communities relying on forests for essential resources,such as firewood,timber,and *** study focuses on two forest-dominant districts in West Bengal of India,namely,Jhargram District and Paschim Medinipur ***,this study aims to enhance the understanding of forest-dependent communities by comparing the standard of living among different village ***,we categorized villages into three classes based on the distance from home to forests,including inner villages,fringe villages,and outer *** focus group discussions and household surveys,we explored the sources of local economy,income sources of household,and reasons for economic diversification in different village *** study findings confirm that substantial variations existed in the income sources and the standard of living in these *** income varied dramatically among the three village classes,with inner villages having greater forest income than fringe villages and outer ***,households in outer villages depended on forests and engaged in diverse economic activities for their *** with inner and fringe villages,households in outer villages derived a significant portion of their income from *** discrepancy can be attributed to challenges,such as inadequate transportation,communication,and underdeveloped market chains in inner ***,these findings emphasize the need to develop sustainable forest management practices,create alternative income-generation opportunities,and improve infrastructure and market access in inner villages,as well as promote economic diversification in outer *** targeted policy measures,these forest-rich regions can achi

关键词： Non-timber forest products(NTFPs) Forest resources Standard of living index Livelihood dependency index Income sources India

Ameliorative Effects of Paclobutrazol via Physio-Biochemical and Molecular Manifestation in Rice under Water Deficit Stress

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Rice science 2024年第5期31卷 603-616,I0065页

作者： Chirag MAHESHWARI Nitin kumar GARG Archana SINGH Aruna TYAGI Indian Council of Agricultural Research-Indian Agricultural Research Institute New Delhi 110012India Sri Karan narendra Agricultural University JobnerRajasthan 303329India

To comprehensively explore the physio-biochemical and molecular changes of paclobutrazol(PBZ) at the ideal dose under water deficit stress(WDS) conditions, we investigated the effects of 100 mg/kg PBZ applied via drenching on various physio-biochemical and molecular parameters in three rice varieties(N22, IR64, and IR64 DTY1.1) under both mild [75%-80% relative water content(RWC)] and severe(60%-65% RWC) WDS conditions. The results showed that PBZ treatment positively influenced the physio-biochemical parameters, significantly increasing dry matter(16.27%-61.91%), RWC(6.48%-16.34%), membrane stability index(4.37%-10.35%), and total chlorophyll content(8.97%-29.09%) in the rice varieties under both mild and severe WDS. Moreover, PBZ treatment reduced drought susceptibility(0.83-0.95) and enhanced drought tolerance efficiency(60.92%-86.78%), indicating its potential as a stress-mitigating agent. Global methylation analysis revealed changes in DNA methylation patterns, indicating the regulatory influence of PBZ on gene expression. The expression analysis of genes involved in the diversification of geranylgeranyl pyrophosphate towards the biosynthesis of abscisic acid, gibberellin acid, and chlorophyll showed alterations in their expression levels, suggesting the involvement of PBZ in the isoprenoid pathway. Overall, this study provides valuable insights into the potential mechanisms by which PBZ modulates physiological and molecular responses in rice plants under WDS. The findings highlight the importance of PBZ as a promising agent for enhancing drought tolerance in rice and offer valuable information for future research in crop stress management.

关键词： rice paclobutrazol drought stress abscisic acid gibberellic acid

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

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

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