检索结果-南通市图书馆

Fast Identification of Symmetrical or Asymmetrical Faults During Power Swings with Dual Use Line Relays

在线全文

学校读者我要写书评

暂无评论

CSEE Journal of Power and Energy Systems 2020年第1期6卷 184-192页

作者： Soumesh chatterjee Biman Kumar Saha Roy National Institute of Technology Agartala AgartalaTripura-799046India National Institute of Technology Durgapur DurgapurWest Bengal-713209India

Increasing power demand,penetration of renew-ables,and limitations of necessary grid expansion are proffering new challenges to existing power system protection and control ***,with the advancement in intelligent elec-tronic devices and relaying technology,fast,accurate and reliable protection schemes can be developed for smart power *** this paper,a new protection scheme based on admittance and power change has been proposed with dual-use line relays to detect symmetrical/asymmetrical faults in power systems.A large number of fault environments have been simulated by varying fault distances from relay location,fault resistance,and power angle in single machine infinite bus and WSCC 9-bus *** crucial decisive fault scenarios *** in/far end faults,faults in series compensated line,faults during asymmetrical swings,switching ON/OFF large loads,single and multi-modal swings have also been verified for the proposed *** this paper,for the first time,detection of faults during power swings have been examined and verified in the presence of wind *** simulation results show the proficiency of the proposed algorithm for detecting faults in the presence or absence of power swings.

关键词： Dual use line relays(DULR) power swing power system protection synchrophasor measurements

COEXISTENCE OF PLANKTON MODEL WITH ESSENTIAL MULTIPLE NUTRIENT IN CHEMOSTAT

维普期刊数据库评论

在线全文

维普期刊数据库

学校读者我要写书评

暂无评论

International Journal of Biomathematics 2013年第6期6卷 79-103页

作者： ANAL chatterjee SAMARES PAL Department of Mathematics University of Kalyani Kalyani 751235 India

We consider a phytoplankton-zooplankton interaction model which depends on two complementary nutrients. For a realistic representation in chemostat plankton ecosystem, we have incorporated various natural phenomena such as dissolved limiting nutrients with nutrient uptake functions and yield constants. For the model with two different constant nutrient inputs with same constant washout rate, existence and stability of non-negative equilibria as well as persistence are given. We analyze the behavior of solution of model in order to answer the biological question and seek to determine the limiting behavior of the surviving organisms and the nutrients. It is observed that the constant nutri- ent inputs of two complementary nutrients play an important role to change steady state behavior of the system. Further it is observed that if the dilution rate of chemostat crosses certain critical value, the system enters into Hopf-bifurcation. Finally, we have derived the explicit algorithm which determines the direction of Hopf-bifurcation. Computer simulations have been carried out to illustrate different analytical results.

关键词： Nutrient plankton yield S-limited R-limited equilibria

The Flight Dynamics of Tapejara,a Pterosaur From the Early Cretaceous of Brazil with a Large Cranial Crest

维普期刊数据库评论

在线全文

维普期刊数据库

学校读者我要写书评

暂无评论

Acta Geologica Sinica(English Edition) 2012年第6期86卷 1377-1388页

作者： Sankar chatterjee R.Jack TEMPLIN Department of Geosciences Museum of Texas Tech University Aerodynamic Laboratory National Research Council

Tapejara wellnhoferi, a small azhdarchoid pterodactyloid from the Early Cretaceous Santana Formation of Brazil, provides critical information about the aerodynamic function of its spectacular head crest. The cranial crests in pterodactyloids were sexually dimorphic and are thought to have evolved in adult males in response to female mate choice. However, the location of cranial crests in front of the center of gravity would create instability in the yaw axis during flight and may seem like a handicap. Vertically aligned webbed feet probably suppressed the yawing rotations and instability from the crest. Here we show that the crest functioned as a front rudder to make agile turn and mediate flight control. A computer simulation model suggests that Tapejara had a large excess of muscle power available above the power required for continuous flapping flight. It could easily takeoff from a perch, ground, or water surface and land safely on the ground. It was an excellent glider with a gliding angle close to 4~ and a cruising speed of 27 km/h. Tapejara could soar efficiently on the windward side of cliffs or circle on rising thermals over tropical waters for efficient long-distance flight. Various control surfaces in the wings of Tapejara analogous to the slat, aileron, elevator, fin, rudder, and horizontal stabilizer of an aircraft made pterodactyloids versatile flyers.

关键词： Tapejara Cretaceous pterodactyloids cranial crest flight Brazil

Geochemistry of Harappan potteries from Kalibangan and sediments in the Ghaggar River： Clues for a dying river

在线全文

学校读者我要写书评

暂无评论

Geoscience Frontiers 2018年第4期9卷 1203-1211页

作者： Anirban chatterjee Jyotiranjan S.Ray Physical Research Laboratory Ahmedabad India

The ephemeral Ghaggar-Hakra River of northwestern India has always been considered to be the remnant of an ancient perennial glacier-fed river（Vedic Saraswati）. The exact reason and timing of major hydrological change of this river remains speculative. The river＇s purported association with the zenith of the Harappan civilisation remains a conjecture because the timings of its fluvial past are still being debated. In this study we have made an attempt to resolve this issue using geochemical provenance of sediments from some dated horizons in the Ghaggar flood plain and that of the material used in the potteries from the Mature Harappan period（4600-3900 yr BP） at Kalibangan. Sampled sedimentary horizons were dated by radiocarbon and optically stimulated luminescence（OSL） methods. Results of our study from the Ghaggar alluvium indicate that the river did have glacial sources during the early Holocene. However, the data from the potteries suggest that during the Mature Harappan period, the sediments in the Ghaggar as used by the potters did not have a higher Himalayan provenance and hence, were not derived from glaciated *** findings imply that during the time of the Mature Harappans the Ghaggar had already become a foothill-fed river.

关键词： Ghaggar alluvium Holocene Sediment provenance Mature Harappan pottery Geochemistry Vedic Saraswati

MULTIGRID TECHNIQUE APPLIED TO LINEAR TIME-DEPENDENT HYPERBOLIC SYSTEMS

在线全文

学校读者我要写书评

暂无评论

Transactions of Nanjing University of Aeronautics and Astronautics 2013年第3期30卷 243-247页

作者： Naren Deore Avijit chatterjee Pimpri Chinchwad College of Engineering Department of Aerospace Engineering India Institution of Technology

A system of linear time-dependent hyperbolic partial differential equations in the form of the time-domain Maxwell′s equations is numerically solved using ageometric multigrid *** multilevel method is an adaptation of Ni′s cell-vertex based multigrid technique,originally proposed for accelerating steady state convergence of nonlinear time-dependent Euler equations of gas *** discuss issues pertaining to the application of the geometric multigrid method to a system of equations where the major issue is of accurately propagating linear waves over large distances leading to major constraints on the required grid resolution in terms of points-perwavelength.

关键词： multigrid linear hyperbolic finite volume maxwell

Effect of coefficient of restitution in Euler-Euler CFD simulation of fluidized-bed hydrodynamics

在线全文

学校读者我要写书评

暂无评论

Particuology 2014年第4期12卷 170-177页

作者： Chanchal Loha Himadri Chattopadhyay Pradip K.chatterjee Thermal Engineering Division CSIR-Central Mechanical Engineering Research InstituteDurgapur 713209India Department of Mechanical Engineering Jadavpur UniversityKolkata 700032India

Collision between particles plays an important role in determining the hydrodynamic characteristics of gas-solid flow in a fluidized bed. In the present work, earlier work （Loha, Chattopadhyay, ＆ chatterjee, 2013） was extended to study the effect of the elasticity of particle collision on the hydrodynamic behavior of a bubbling fluidized bed filled with 530-~m particles. The Eulerian-Eulerian two-fluid model was used to simulate the hydrodynamics of the bubbling fluidized bed, where the solid-phase properties were calculated by applying the kinetic theory of granular flow. To investigate the effect of the elasticity of particle collision, different values of the coefficient of restitution were applied in the simulation and their effects were studied in detail. Simulations were performed for two different solid-phase wall boundary conditions. No bubble formation was observed for perfectly elastic collision. The bubble formation started as soon as the coefficient of restitution was set below 1.0, and the space occupied by bubbles in the bed increased with a decrease in the coefficient of restitution. Simulation results were also compared with experimental data available in the literature, and good agreement was found for coefficients of restitution of 0.95 and 0.99.

关键词： Coefficient of restitution Fluidization Hydrodynamics Computational fluid dynamics Euler-Euler approach

Euler-Euler CFD modeling of fluidized bed:Influence of specularity coefficient on hydrodynamic behavior

在线全文

学校读者我要写书评

暂无评论

Particuology 2013年第6期11卷 673-680页

作者： Chanchal Loha Himadri Chattopadhyay Pradip K.chatterjee Thermal Engineering Group CSIR-Central Mechanical Engineering Research Institute Department of Mechanical Engineering Jadavpur University

Euler-Euler two-fluid model is used to simulate the hydrodynamics of gas-solid flow in a bubbling flu- idized bed with Geldert B particles where the solid property is calculated by applying the kinetic theory of granular flow （KTGF）. Johnson and Jackson wall boundary condition is used for the particle phase, and different amount of slip between particle and wall is given by varying the specularity coefficient （φ） from 0 to 1. The simulated particle velocity, granular temperature and particle volume fraction are compared to investigate the effect of different wall boundary conditions on the hydrodynamic behavior, Some of the results are also compared with the available experimental data from the literature. It was found that the model predictions are sensitive to the specularity coefficient. The hydrodynamic behavior deviated sig- nificantly for φ = 0 and φ = 0.01 with maximum deviation found at φ = 0 i.e. free-slip condition. However, the overall bed height predicted by all the conditions is similar.

关键词： Fluidized bed Hydrodynamics Specularity coefficient CFD

Advanced microemulsion synthesis and characterization of wollastonite （CaSiO3）fpolystyrene one-dimensional nanorods with core-shell structures

在线全文

学校读者我要写书评

暂无评论

Particuology 2017年第1期15卷 118-128页

作者： Aniruddha chatterjee Prashant Khobragade, Satyendra Mishra Jitendra Naik University Institute of Chemical Technology North Maharashtra University Jalgaon 425001 Maharashtra India

In this work, one-dimensional core-shell nanorods （CSNRs; 185-250nm wide and 1-1.5μm long） consisting of triethoxyvinylsilane-modified wollastonite （CaSiO3） nanorods （MWNRs） as a core and polystyrene as a shell with uniform size were successfully synthesized using an advanced microemulsion technique. The effect of varying the surfactant cetyltrimethylammonium bromide （producing CSNRSCTAB） or sodium dodecyl sulphate （producing CSNRSSDS） upon the size and morphology of the CSNRs was investigated by field-emission scanning electron microscopy （FE-SEM）. X-ray diffractometry and Fourier transform infrared spectrophotometer revealed the existence of a strong interaction between the MWNRs and polystyrene, which implies that the polymer chains were successfully grafted onto the surface of the MWNRs. The CSNRs were blended with polypropylene by melt processing, and the effect of the CSNRs upon the morphological properties of the polypropylene matrix was investigated by FE-SEM and atomic force microscopy. It was observed that the polystyrene chains that grafted onto the CaSiO3 nanorods interfered with the aggregation of CaSiO3 nanorods in the polypropylene matrix and thus improved the compatibility of the CaSiO3 nanorods with the polypropylene matrix. Furthermore, the compatibility of CaSiO3 nanorods with polypropylene of CSNRsDs/polypropylene was superior to that of CSNRCTAB/polypropylene.

关键词： Core-shell structures Atomized microemulsion One-dimensional nanorods

D-optimal Designs for Multiresponse Linear Models with a Qualitative Factor Under General Covariance Structure

维普期刊数据库评论

在线全文

维普期刊数据库

学校读者我要写书评

暂无评论

Acta Mathematicae Applicatae Sinica 2023年第4期39卷 878-885页

作者： Rong-Xian YUE Xin LIU Kashinath chatterjee College of Mathematics and Science Shanghai Normal UniversityShanghai 200234China College of Science Donghua UniversityShanghai 201620China Department of Statistics Visva-Bharati UniversitySantiniketanIndia

This paper considers a linear regression model involving both quantitative and qualitative factors and an m-dimensional response variable y. The main purpose of this paper is to investigate D-optimal designs when the levels of the qualitative factors interact with the levels of the quantitative factors. Under a general covariance structure of the response vector y, here we establish that the determinant of the information matrix of a product design can be separated into two parts corresponding to the two marginal designs. Moreover, it is also proved that D-optimal designs do not depend on the covariance structure if we assume hierarchically ordered system of regression models.

关键词： D-optimal designs Multiresponse linear models Qualitative factors