检索结果-南通市图书馆

Optical characterization of nano-sized organic carbon particles emitted from a small gasoline engine

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

Particuology 2013年第3期11卷 249-255页

作者： Bireswar Paul Amitava datta Aparna datta Abhijit Saha department of Power Engineering Jadavpur University UGC-DAE Consortium for Scientific Research

The nano-sized organic carbon （NOC） particles emitted from a small gasoline engine were characterized using various ex situ optical techniques to assess their hazardous impact. The exhaust gas was sampled iso-kinetically by a quartz probe and passed through de-ionized water to gather the hydrophilic car- bonaceous particulates as hydrosol. The hydrodynamic diameter of the particles ranged between 1.7 and 3.6 nm at no load, with a mean diameter of 2.4 nm. The particle size in the engine exhaust was found to increase at higher loads, which is attributed to coagulation of the particles. The chemical structure of the particles was analyzed using UV-vis and infra-red spectroscopy. Both the band gap energy and oscillator strength data evaluated from the UV-vis absorbance showed that the NOC particles contained polyaromatic hydrocarbon structures with three to five aromatic rings. Infra-red spectroscopy analysis further confirmed the presence of aliphatic and carbonyl functionalities in the aromatic structures of the particles. The fine size of the particles, their high number concentration for the type of the engine under study and their structural features, make the particles extremely hazardous for environment and health.

关键词： Gasoline engine Combustion Emission Carbon nano-particle Characterization

Application of pressure-state-response approach for developing criteria and indicators of ecological health assessment of wetlands:a multi-temporal study in Ichhamati floodplains,India

在线全文

学校读者我要写书评

暂无评论

Ecological Processes 2023年第1期12卷 475-494页

作者： Jibananda Gayen de.ajit datta department of Geography Jadavpur UniversityKolkata 700032India department of Geography Sree Chaitanya CollegeHabra 743268India

Background Tropical floodplain wetlands are among the most disturbed and intensively harvested *** sustainable management is often hindered due to the lack of comprehensive,coherent,and standardized assessment frameworks of wetland ecological health(WEH).In this study,a set of appropriate criteria and indicators(C&I)of WEH assessment was developed and tested on seven wetlands of River Ichhamati,eastern *** Based on the pressure-state-response(PSR)approach,evaluation indicators representing ecological,socio-economic,and institutional sustainability issues of floodplain wetland systems were either selected or formulated through literature survey and stakeholder *** of indicators were assigned by the entropy weighting method and then used in the Technique for Order of Preference by Similarity to Ideal Solution model to determine the Euclidean distances of each wetland from the positive ideal solution and negative ideal ***,a comprehensive wetland ecological health index(CWEHI)was constructed from these distances to portray the condition of any PSR system component in a wetland under a fivefold classification scheme,namely‘excellent health’(CWEHI≥0.81),‘good health’(0.61-0.80),‘moderate health’(0.41-0.60),‘weak health’(0.21-0.40),and‘morbid’(≤0.20).Results The developed C&I set contains 8 criteria and 38 indicators under pressure component,7 criteria and 49 indicators under state component,as well as 4 criteria and 18 indicators under response *** applied in 2016 and 2022,it was found that the Panchita and Aromdanga wetlands were continuously in weak and morbid health status,while the Madhabpur wetland always showed an excellent or good status for all *** of other wetlands oscillated between moderate and morbid health across assessment years and system *** The developed C&I set was found to be a flexible,holistic,and refined framework that could be applied elsewhere in sim

关键词： Entropy weighting method Environmental indicator Floodplain wetland TOPSIS Wetland influence zone Wetland ecological health

同方期刊数据库

Modeling of hydrodynamics in a bubbling fluidized-bed gasifier and evaluation of the inter-phase gas exchange rate under different operating conditions

在线全文

学校读者我要写书评

暂无评论

Particuology 2016年第2期14卷 151-158页

作者： Bijoy Das Amitava datta development Consultants Pvt. Ltd Salt Lake City Kolkata 700 091 India department of Power Engineering Jadavpur University Salt Lake Campus Kolkata 700 098 India

A fluid dynamic model of a bubbling fluidized-bed coal gasifier is presented considering two-phase theory of fluidization. The effects of the gasifier temperature and bed particle size on the hydrodynamic char- acteristics of both the bubble and emulsion phases of the gasifier bed are studied. The bubble diameter, bubble velocity, and bubble area fraction are evaluated for the bubble phase, whereas the gas velocity and porosity are studied for the emulsion phase, along the height of the bed. Finally, the rate of inter-phase gas exchange from the emulsion phase to bubble phase is calculated under different operating conditions.

关键词： Bubbling fluidized bed Gasifier Gas exchange rate Bubble Emulsion

Boulder-induced form roughness and skin shear stresses in a gravel-bed stream

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

Journal of Mountain Science 2024年第1期21卷 346-360页

作者： DAS Ratul datta Akash Civil Engineering department National Institute of Technology AgartalaAgartala-799046India

Boulder spacing in mountain rivers and near-wake flow zones within the boulder array is very useful for fish habitat and growth of aquatic *** present study aims to investigate how the boulder array and spacing influence the near-bed flow structures in a gravel-bed *** are staggered over a gravel-bed stream with three different inter-boulder spacing namely(a)large(b)medium and(c)small *** acoustic Doppler velocimeter was used for flow measurements in a rectangular channel and the results were compared with those acquired from numerical *** time-averaged velocity profiles at the near-wake flow zones of boulders experience maximum flow retardation which is an outcome of the boulder-induced form *** ratio of velocity differences associated to form and skin roughness and its positive magnitude reveals the dominance of form roughness closest to the *** roughness computed is 1.75 to 2 times higher than the skin roughness at the near-wake flow *** particular,the collective immobile boulders placed at different inter-boulder spacings developed high and low bed shear stresses closest to the *** low bed shear stresses characterised by a secondary peak developed at the trough location of the boulders is attributed to the skin shear ***,the spatial averaging of time-averaged flow quantities gives additional impetus to present an improved illustration of fluid shear *** formation of form-induced shear stress is estimated to be 17%to 23%of doubleaveraged Reynolds shear stress and partially compensates for the damping of time-averaged Reynolds shear stress in the interfacial *** quadrant analysis of spatial velocity fluctuations depicts that the form-induced shear stresses are dominant in the interfacial sub-layer and have no significance above the gravel-bed surface.

关键词： Array of boulders Near wake flow zones Velocity distributions Skin roughness Form induced shear stresses

Heat Transfer and Thermal Characteristics Effects on Moving Plate Impinging from Cu-Water Nanofluid Jet

在线全文

学校读者我要写书评

暂无评论

Journal of Thermal Science 2020年第1期29卷 182-193页

作者： datta Abanti KUMAR Sonal HALdeR Pabitra department of Aerospace Engineering and Applied Mechanics Indian Institute of Engineering Science and Technology

The present article is focused on modelling of flow and heat transfer behaviour of Cu-water nanofluid in a confined slot jet impingement on hot moving *** parameters such as various moving plate velocities,nanoparticles at various concentrations,variation in turbulent Reynolds number and jet nozzle to plate distance have been considered to study the flow field and convective heat transfer performance of the *** of distribution of local and average Nusselt number and skin friction coefficients at the plate surface are shown to elucidate the heat transfer and fluid flow *** analysis of both stream function and isotherm contours are carried out to perceive the flow pattern and heat transfer mechanism due to moving *** results revealed that average Nusselt number significantly rises with plate velocity in addition with jet inlet Reynolds *** of the average Nusselt numbers are presented.

关键词： Cu-water nanofluid,multiphase mixture model moving plate jet impingement CFD

Capture the variation of the pore pressure with different geological age from seismic inversion study in the Jaisalmer sub-basin,India

在线全文

学校读者我要写书评

暂无评论

Petroleum Science 2020年第6期17卷 1556-1578页

作者： Raman Chahal Saurabh datta Gupta department of Applied Geophysics Indian Institute of Technology(Indian School of Mines)DhanbadDhanbadJharkhand 826004India

Geoscientific evidence shows that various parameters such as compaction,buoyancy effect,hydrocarbon maturation,gas effect and tectonic activities control the pore pressure of sub-surface *** controlled geoscientific data in the tectonically active areas is significantly useful for robust estimation of pre-drill pore *** reservoir which is tectonically complex and pore pressure is changing frequently that circumference motivated us to conduct this *** changes in pore pressure have been captured from the fine-scale to the broad scale in the Jaisalmer *** pressure variation has been distinctly observed in pre-and post-Jurassic age based on the current ***-stack seismic inversion study was conducted to capturing the variation of pore *** of low-frequency spectrum and integrated interval velocity model provided a detailed feature of pore pressure in each compartment of the study *** pressure estimated from well log data was correlated with seismic inversion based *** on the current study one well has been proposed where pore pressure was estimated and two distinguished trends are identified in the study *** approaches of the current study were analysed thoroughly and it will be highly useful in complex reservoir condition where pore pressure varies frequently.

关键词： Pore pressure Seismic inversion Clastic and carbonate reservoir

Large-signal characterization of DDR silicon IMPATTs operating in millimeter-wave and terahertz regime

在线全文

学校读者我要写书评

暂无评论

Journal of Semiconductors 2013年第10期34卷 46-53页

作者： Aritra Acharyya Jit Chakraborty Kausik Das Subir datta Pritam de Suranjana Banerjee J.P.Banerjee Institute of Radio Physics and Electronics University of Calcutta92APC RoadKolkata 700009India Supreme Knowledge Foundation Group of Institutions Sir J.C.Bose School of Engineering1Khan RoadMankunduHooghlyWest Bengal 712139India Academy of Technology West Bengal University of TechnologyAdisaptagramHooghly 712121West BengalIndia

The authors have carried out the large-signal characterization ofsilicon-based double-drift region （DDR） impact avalanche transit time （IMPATT） devices designed to operate up to 0.5 THz using a large-signal simulation method developed by the authors based on non-sinusoidal voltage excitation. The effect of band-to-band tunneling as well as parasitic series resistance on the large-signal properties of DDR Si IMPATTs have also been studied at different mm-wave and THz frequencies. Large-signal simulation results show that DDR Si IMPATT is capable of delivering peak RF power of 633.69 mW with 7.95% conversion efficiency at 94 GHz for 50% voltage modulation, whereas peak RF power output and efficiency fall to 81.08 mW and 2.01% respectively at 0.5 THz for same voltage modulation. The simulation results are compared with the experimental results and are found to be in close agreement.

关键词： band to band tunneling DDR silicon IMPATTs large-signal simulation millimeter-wave series resistance terahertz regime

Hybrid Offset Slider Crank Mechanism for Anthropomorphic Flexion in Prosthetic Hands

在线全文

学校读者我要写书评

暂无评论

Journal of Bionic Engineering 2023年第1期20卷 308-322页

作者： Banibrata datta Sekar Anup Chander Srikanth Vasamsetti CSIR-CSIO Sector-30CChandigarh160030India

The underactuated fingers used in prosthetic hands account for a large part of design consideration in anthropomorphic prosthetic hand *** are considerable numbers of designs available for underactuated prosthetic fingers in literature but,emulating the anthropomorphic flexion movement is still a challenge due to the complex nature of the *** address this challenge,a hybrid mechanism using both linkage-based mechanism and tendon-driven actuation has been proposed in this *** presented mechanism includes a novel offset slider-crank-based finger that has been designed using a combination of different lengths of cranks and connecting *** prototypes of both the new mechanism and the conventional tendon-driven mechanism are constructed and compared experimentally based on interphalangeal joint angle trajectory during *** angles achieved through the new hybrid mechanism are compared with the conventional tendon-driven mechanism and the Root Mean Square Error(RMSE)values have been calculated by comparing to the anthropomorphic flexion angles of the published *** RMSE values calculated for three interphalangeal joints of the hybrid mechanism are found to be less than their counter-parts of the conventional tendon-driven *** addition to achieving resemblance to anthropomorphic flexion angles,the mechanism is designed within the anthropometric human finger dimensions.

关键词： Anthropomorphism Hybrid mechanism Prosthetic-Slider-crank.Underactuated

Effects of patch size, disturbances on diversity and structural traits of tropical semi-evergreen forest in the lowland Indo Burma hotspot: implication on conservation of the threatened tree species

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

Journal of Mountain Science 2016年第8期13卷 1397-1410页

作者： Koushik MAJUMDAR Badal Kumar datta Plant Taxonomy and Biodiversity Laboratory Department of Botany Tripura University

Information on geographic distribution, population and threat status of most globally red listed species in the Indo Burma zone are inadequate. Given the increase in the prevalence of isolated forest patches in the part of this hotspot, evaluation is necessary on how size of the remnant forest patches and on-going disturbances affects structure and diversity of remaining habitats including the population of some globally threatened tree species. Quantitative vegetation inventory by 500 m long and lO m wide （0.5 ha） line transects were randomly set in nine fragmented tropical semi-evergreen forest patches in Tripura, Northeast India. The studied forests patches grouped into small, medium and large based on their respected sizes. Spatial variability was analysed in woody species diversity and structure along the patch size gradients and their response to both patch size and anthropogenic disturbances. Out of 167 species, 13 identified as red-listed species by IUCN under the present inventory. Most of the diversity and structural parameters showed statistically significant positive response with the forest patch size, except for stand dominance, disturbance, sapling density and number of aggregated distribution pattern decreased when patch size increased. In addition, most of the diversity and structural attributes showed negative response with disturbances. Present baseline data would serve as an effective tool for management and protection of this important forest type. Future habitat restoration programme and strategies for relocation of additional population and re-introduction of those globally threatened trees are recommended.

关键词： Forest diversity Semi-evergreen forest Threatened species Population composition IndoBurma zone