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Wyświetlanie 1-22 z 22
Tytuł:
Study of Refractive Indices, Density and Order Parameters of Two Nematogens and Their Eutectic Mixture
Autorzy:
Datta Sarkar, S.
Choudhury, B.
Powiązania:
https://bibliotekanauki.pl/articles/1535803.pdf
Data publikacji:
2010-10
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
78.15.+e
64.70.M-
Opis:
The compounds 5-pentyl-2-(4'-cyanophenyl) pyrimidine [CM 7035] and 4-n-butyl-4'-ethoxytolan [PTP4O2] and mixtures of different mole fractions of them show nematic phase with supercooling effect. From the phase diagram the equimolar mixture is found to be the eutectic mixture. Temperature variation of the density and refractive indices ($n_{o}$, $n_{e}$) of the pure compounds and their eutectic mixture have been reported here. The density and birefringence values of the eutectic mixture are found to be less than that of pure compounds. However the average refractive index values of eutectic mixture almost coincide with those of CM 7035 which are much less than those of PTP4O2. The refractive indices and density values have been analyzed to obtain the orientational order parameters. Experimental order parameter values of the pure compounds and the eutectic mixture are compared with theoretical Maier-Saupe values. The possible reasons for disagreement between theoretical and experimental values for the pure compounds are discussed. The agreement between theoretical and experimental order parameters are fairly good for the eutectic mixture.
Źródło:
Acta Physica Polonica A; 2010, 118, 4; 665-669
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Ethological study of flower visiting insects in two parks, Kolkata, India
Autorzy:
Sarkar, S.
Nandy, A.
Talapatra, S.N.
Powiązania:
https://bibliotekanauki.pl/articles/11497.pdf
Data publikacji:
2014
Wydawca:
Przedsiębiorstwo Wydawnictw Naukowych Darwin / Scientific Publishing House DARWIN
Tematy:
ethology
flower
visiting insect
insect
park
urban park
Calcutta city
India
Opis:
Flower visiting insects attract by the flowers colour, shape, size and fragrance as pollinator. This is a mutual relationship between flowers and insects. The present study aims to know behavioural response or ethology of flower visiting insect in relation to particular flower and/or probable atmospheric changes in two managed parks, Kolkata, India. The study areas were selected as per heavily-populated neighborhoods, nearby office buildings, nearby roads and continuous vehicular movements, human interactions as visitors. The study was carried out at 2 sampling stations viz (i) Elliot park and (ii) Agri-Horticulture Society. The flower species were selected viz. Helianthus annuus (sunflower), Petunia sp. (petunia) and Buganvilia spectabilis (Buganvilia) planting above mentioned areas because these species are more common among other species. In each flower, behavioural response or ethology of visiting insects were studied by visual observation and total 10 flowers of each species were observed randomly. The present results clearly indicate that various insects were majorly showed foraging and feeding behaviour and only mating behaviour was found in two species. This study is a preliminary assessment of flower visiting insects’ ethology but further researches are needed in relation to pollination efficiencies of flower visiting insects in the particular flower and air pollution load nearby area by using instruments. It was concluded that insect visitors are showing foraging and feeding behavior but only two species were showed mating behaviour, which may be due to the vehicular air pollution because two parks are located nearby roads and continuous vehicular movements were observed.
Źródło:
International Letters of Natural Sciences; 2014, 12, 1
2300-9675
Pojawia się w:
International Letters of Natural Sciences
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Failure analysis of laminated composite plate under hygro-thermo mechanical load and optimisation
Autorzy:
Choudhury, A.
Mondal, S. C.
Sarkar, S.
Powiązania:
https://bibliotekanauki.pl/articles/264515.pdf
Data publikacji:
2019
Wydawca:
Uniwersytet Zielonogórski. Oficyna Wydawnicza
Tematy:
współczynnik wytrzymałości
kompozyt hybrydowy
obciążenia
first ply failure load
last ply failure load
strength ratio
fiber orientation angle
hybrid composite
Opis:
Failure analysis of laminated composite plates for different mechanical, thermo mechanical and hygro-thermo mechanical loads for different ply thicknesses, stacking sequences, fiber orientation angles and composite material systems is presented in the paper. A comparative study of different failure theories is also presented in the paper. The effect of fiber orientation angles on the first ply failure load is also studied. A hybrid composite laminate is developed based on the first ply failure load which minimizes weight and cost. The last ply failure load based on fully discounted method is calculated for different stacking sequences. An optimum composite material system and laminate layup is studied for a targeted strength ratio which minimizes weight.
Źródło:
International Journal of Applied Mechanics and Engineering; 2019, 24, 3; 509-526
1734-4492
2353-9003
Pojawia się w:
International Journal of Applied Mechanics and Engineering
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Effects of Hall current on unsteady hydromagnetic free convection flow past an impulsively moving vertical plate with Newtonian heating
Autorzy:
Seth, G. S.
Sarkar, S.
Sharma, R.
Powiązania:
https://bibliotekanauki.pl/articles/264598.pdf
Data publikacji:
2016
Wydawca:
Uniwersytet Zielonogórski. Oficyna Wydawnicza
Tematy:
przepływ konwekcyjny
transformacja Laplace'a
tarcie
hydromagnetic free convection flow
Newtonian heating
Hall current
porous medium
INVLAP routine in Matlab
Opis:
An investigation of unsteady hydromagnetic free convection flow of a viscous, incompressible and electrically conducting fluid past an impulsively moving vertical plate with Newtonian surface heating embedded in a porous medium taking into account the effects of Hall current is carried out. The governing partial differential equations are first subjected to the Laplace transformation and then inverted numerically using INVLAP routine of Matlab. The governing partial differential equations are also solved numerically by the Crank-Nicolson implicit finite difference scheme and a comparison has been provided between the two solutions. The numerical solutions for velocity and temperature are plotted graphically whereas the numerical results of skin friction and the Nusselt number are presented in tabular form for various parameters of interest. The present solution in special case is compared with a previously obtained solution and is found to be in excellent agreement.
Źródło:
International Journal of Applied Mechanics and Engineering; 2016, 21, 1; 187-203
1734-4492
2353-9003
Pojawia się w:
International Journal of Applied Mechanics and Engineering
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
MHD natural convection flow with radiative heat transfer past an impulsively moving vertical plate with ramped temperature in the presence of hall current and thermal diffusion
Autorzy:
Seth, G. S.
Mahato, G. K.
Sarkar, S.
Powiązania:
https://bibliotekanauki.pl/articles/955266.pdf
Data publikacji:
2013
Wydawca:
Uniwersytet Zielonogórski. Oficyna Wydawnicza
Tematy:
konwekcja naturalna
dyfuzja termiczna
promieniowanie cieplne
MHD natural convection
Hall current
ramped temperature
thermal diffusion
thermal radiation
Opis:
An investigation on an unsteady MHD natural convection flow with radiative heat transfer of a viscous, incompressible, electrically conducting and optically thick fluid past an impulsively moving vertical plate with ramped temperature in a porous medium in the presence of a Hall current and thermal diffusion is carried out. An exact solution of momentum and energy equations, under Boussinesq and Rosseland approximations, is obtained in a closed form by the Laplace transform technique for both ramped temperature and isothermal plates. Expressions for the skin friction and Nusselt number for both ramped temperature and isothermal plates are also derived. The numerical values of fluid velocity and fluid temperature are displayed graphically versus the boundary layer coordinate y for various values of pertinent flow parameters for both ramped temperature and isothermal plates. The numerical values of the skin friction due to primary and secondary flows are presented in tabular form for various values of pertinent flow parameters.
Źródło:
International Journal of Applied Mechanics and Engineering; 2013, 18, 4; 1201-1220
1734-4492
2353-9003
Pojawia się w:
International Journal of Applied Mechanics and Engineering
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Effect of Temperature on the Refractive Indices of Liquid Crystals and Validation of a Modified Four-Parameter Model
Autorzy:
Thingujam, K.
Sarkar, S.
Choudhury, B.
Bhattacharjee, A.
Powiązania:
https://bibliotekanauki.pl/articles/1418322.pdf
Data publikacji:
2012-10
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
78.15.+e
78.20.Fm
64.70.M-
Opis:
The variation of refractive indices with temperature of three pure nematogenic compounds 5OCB, CPHB and 6CHBT were studied experimentally using thin prism technique. The refractive indices $n_{o}$ and $n_{e}$ were measured using 633 nm lines from a He-Ne laser. A modified four-parameter model was taken which is based on the Vuks equation describing the effect of temperature on the refractive indices of liquid crystals. In this paper we report the variation of refractive indices of these three liquid crystals with temperature, using the thin prism method. The variation in birefringence was determined experimentally. The variation in refractive indices and birefringence were also fitted theoretically using the modified Vuks equation. On comparison, the theoretically fitted values show close agreement with the experimental values.
Źródło:
Acta Physica Polonica A; 2012, 122, 4; 754-757
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Assessment of flower visiting insects diversity as pollinators in two parks, Kolkata, India
Autorzy:
Chowdhury, S.
Sarkar, S.
Nandy, A.
Talapatra, S.N.
Powiązania:
https://bibliotekanauki.pl/articles/11677.pdf
Data publikacji:
2014
Wydawca:
Przedsiębiorstwo Wydawnictw Naukowych Darwin / Scientific Publishing House DARWIN
Tematy:
assessment
flower
visiting insect
diversity
pollinator
park
biomonitoring
Kolkata city zob.Calcutta city
India
Calcutta city
Opis:
Insects are depends upon autotrophs and they attract by the flowers colour and shape as pollinator. This is a mutual relationship between flowers and insects. The present study aims to determine flower visiting insect diversity as pollinators in two parks as biomonitoring of automobile air pollution exposure, landscape changes and/or human interactions. The study areas were selected as per heavily-populated neighborhoods, nearby office buildings, nearby roads and continuous vehicular movements, human interactions as visitors, where fences and high levels of human disturbance are common. The study was carried out at 2 sampling stations viz (i) Elliot park and (ii) Agri-Horticulture Society. The flower species were selected viz. Helianthus annuus, Petunia sp. and Buganvilia spectabilis planting above mentioned areas because these species are more common among other species. In each flower, diversity of visiting insects were studied by qualitative and quantitative assessment. Indices were Species richness, Index of Dominance, Relative abundance, Shannon-Wiener Diversity Index and Evenness Index for insects for all selected sites were calculated using the statistical formulae. The present results clearly indicate that the flower visiting insects are very less in numbers on three flowering species and index values were decreased. This study is a preliminary assessment of flower visiting insects diversity but further researches are needed in relation to pollination efficiencies of flower visiting insects and biochemical and genetic damage study of flowers as well as air pollution load by using instruments. It was concluded that three flowering species viz. sunflower, petunia and bougainvillea are very common both the parks but insect visitors are common but present less in number, which may be due to the vehicular pollution and/or human interference and/or landscape changes due to nearby neighborhood blocks, office and residential buildings etc.
Źródło:
International Letters of Natural Sciences; 2014, 10
2300-9675
Pojawia się w:
International Letters of Natural Sciences
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Assessment of bird diversity as bioindicators in two parks, Kolkata, India
Autorzy:
Chowdhury, R.
Sarkar, S.
Nandy, A.
Talapatra, S.N.
Powiązania:
https://bibliotekanauki.pl/articles/11495.pdf
Data publikacji:
2014
Wydawca:
Przedsiębiorstwo Wydawnictw Naukowych Darwin / Scientific Publishing House DARWIN
Tematy:
assessment
bird diversity
bioindicator
vehicular traffic
vehicular pollution
urban park
biomonitoring
landscape change
park
Calcutta city
India
Opis:
The trees of parks and gardens support many species, the survival of urban-dwelling species mainly bird species. Birds amongst other species provide a wide range of environmental and social functions to cities and urban dwellers. The present study aims to know bird diversity in two parks as bioindicator of automobile air pollution exposure, landscape changes and/or human interactions. The study areas were selected as per heavily-populated neighborhoods, nearby office buildings, nearby roads and continuous vehicular movements, human interactions as visitors, where high levels of human disturbance are common. The study was carried out at 2 sampling stations viz (i) Elliot park and (ii) Agri-horticulture Society. The bird species diversity was studied by qualitative and quantitative assessment. Indices were Species richness, Index of Dominance, Relative abundance, Shannon-Wiener Diversity Index and Evenness Index for birds for all selected sites were calculated using the statistical formulae. The present results as bioindicators bird species clearly indicate that the bird species are very few in numbers in both the parks. When comparison made between both the parks, it was observed less number of bird varieties (16 types) in Elliot park than varieties (9 types) more less in number in Agri-horticulture society. This study is a preliminary assessment of bird diversity but further researches are needed in relation to biochemical and genetic damage study as well as air pollution load by using instruments. In the present study it was concluded that the less numbers of birds and their different diversity indices were found a decreasing trends, though there no attempt has been made on physico-chemical properties of present air pollutants. The less number of varieties of bird species are as tolerant bioindicators, which may be due to the vehicular pollution and/or human interference and/or landscape changes due to nearby neighborhood blocks, office and residential buildings, continuous movement of vehicles etc.
Źródło:
International Letters of Natural Sciences; 2014, 11, 2
2300-9675
Pojawia się w:
International Letters of Natural Sciences
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Modelling and measurement of bubble formation and growth in electroflotation processes
Autorzy:
Sarkar, S. K.
Machniewski, P.M.
Evans, G.M.
Powiązania:
https://bibliotekanauki.pl/articles/184977.pdf
Data publikacji:
2013
Wydawca:
Polska Akademia Nauk. Czytelnia Czasopism PAN
Tematy:
electroflotatio
bubble diameter
detachment
mass transfer
CFD modeling
średnica bańki
oderwanie
masa transferu
modelowanie CFD
Opis:
Electroflotation is used in the water treatment industry for the recovery of suspended particles. In this study the bubble formation and release of hydrogen bubbles generated electrolytically from a platinum cathode was investigated. Previously, it was found that both the growth rate and detachment diameter increased with increasing wire diameter. Conversely, current density had little effect on the released bubble size. It was also found that the detached bubbles rapidly increased in volume as they rose through the liquid as a result of decreasing hydrostatic pressure and high levels of dissolved hydrogen gas in the surrounding liquid. The experimental system was computationally modelled using a Lagrangian-Eulerian Discrete Particle approach. It was revealed that desorption of gaseous solutes from the electrolyte solution, other than hydrogen, may have a significant impact on the diameter variation of the formed bubbles. The simulation confirmed that liquid circulation, either forced or induced by the rising bubble plume, influences both the hydrogen supersaturation (concentration) in the neighbourhood of the electrode and the size of the resulting bubbles.
Źródło:
Chemical and Process Engineering; 2013, 34, 3; 327-336
0208-6425
2300-1925
Pojawia się w:
Chemical and Process Engineering
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Behavioural toxicology of midge larvae Chironomous sp. after acute in situ exposure of different industrial effluents and drinking water
Autorzy:
Bhunia, D.
Sarkar, S.
Banerjee, K.
Nandy, A.
Talapatra, S.N.
Powiązania:
https://bibliotekanauki.pl/articles/11385.pdf
Data publikacji:
2014
Wydawca:
Przedsiębiorstwo Wydawnictw Naukowych Darwin / Scientific Publishing House DARWIN
Tematy:
behavioural activity
toxicology
midge
larva
Chironomus
in situ exposure
industrial effluent
drinking water
Opis:
Behavioural activities in relation to toxicological aspects involve behavioural changes of aquatic organisms under the exposure of a contaminant. The present study aims to know behavioural activities of midge larvae Chironomus sp. at the in-situ acute exposure of different chemicals containing wastewater viz. lead-acid battery industrial effluent, mixed industrial effluent and fresh tap water (chlorinated) as drinking water in comparison to control (dechlorinated) water sample (aged tap water). The Chironomus larvae were kept in three different experimental chambers (perforated wall test vessels) with the exposure of different water samples. These samples were made with no dilution, 50 % dilution, 2.5 % dilution and control water sample. The behavioral activities for larvae of Chironomus sp. were measured at 0h, 2h, 24h and 48 h in in-situ condition. The behavioral activities viz. crawling, looping, ventilation, paralyses and subsequently death of the larvae were recorded in the field condition. A significant differences (P < 0.05, P < 0.01 and P< 0.001) were observed with increasing time of exposure while in few cases the data were increased without significance level. It was recorded that after exhibiting behavioural activities viz. crawling, looping, ventilation and paralyses finally all species were died 100 % of the population in lead acid battery effluent following both 24h and 48hr exposure. In addition, death of larvae were 70 % in mixed industrial effluent and 50 % in fresh tap water (chlorinated) after 48h exposure as compared to control sample water. In conclusion, the present results indicate that the larvae of Chironomous sp. are suitable indicators in the evaluation of the effluent quality in the studied stream, potential to know by behavioural toxicological study for heavy metals and organic pollution. Although it is a preliminary observation by assessing behavioural toxicology but future study in relation to biochemical and genetic damage of Chironomous larvae with the exposure of toxic water samples will provide bigger view.
Źródło:
International Letters of Natural Sciences; 2014, 14
2300-9675
Pojawia się w:
International Letters of Natural Sciences
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Survey of indoor air pollution and health symptoms at residential buildings
Autorzy:
Sarkar, S.
Nandy, A.
Talapatra, S.N.
Basu, R.
Mukhopadhyay, A.
Powiązania:
https://bibliotekanauki.pl/articles/11531.pdf
Data publikacji:
2014
Wydawca:
Przedsiębiorstwo Wydawnictw Naukowych Darwin / Scientific Publishing House DARWIN
Tematy:
indoor air
air pollution
air pollutant
household product
human health
hazard symptom
residential building
Opis:
This survey work summarizes the generation of indoor air pollutants (IAPs) through household products and activities and also the probable health symptoms of IAPs were discussed through questionnaire in the residential buildings of urban and semi urban area when compared to rural (control) area by door to door survey. The IAPs are categorized as physical, chemical and biological and surveyed as per the product(s) usage in the closed room of buildings. The survey results of IAPs generated from household products and activities, these are asbestos, fine particulate matters and ash as physical pollutants. The chemical pollutants are carbon mono and di oxide gases, phthalates; DDT, chlordane, heptachlor, o-phenylphenol; PBDEs, Formaldehyde, Other Aldehydes, lead, benzene, chloroform, para-dichlorobenzene, methylene chloride, perchloroethylene, styrene, benzene, formaldehyde, terpenes, styrene, phthalate esters, toluene, Propellant, pesticides, PAH, NOx, acrylamide, VOCs, acetone, HCl gas and biological pollutants are bacteria, fungi, viruses, house dust mites, animal dander; cockroaches, microbial spore. In respect to established health impact data, the health symptoms were recorded after survey in two areas viz. urban and semi urban area. The health symptoms were recorded as eye, nose, and throat irritation; allergic reactions, respiratory irritation, aggravated asthma, influenza and other infectious diseases may be the generation of IAPs. The urban and semi urban area are compared with rural (control) area in which no symptoms were found as per discussion. In the present survey it was concluded that the generation of IAPs may from household products and activities in the urban and semi urban area due to less ventilation facilities when compared to rural (control) area. This is a preliminary observation, further researches are needed in relation to measurement of physical, chemical and biological indoor pollutants in closed room of residential buildings and also health hazards study of residents by haematological, biochemical, enzymological and genotoxicological parameters.
Źródło:
International Letters of Natural Sciences; 2014, 08, 1
2300-9675
Pojawia się w:
International Letters of Natural Sciences
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
A study on the occurrence of Asian open bill stork, Anastomus oscitans in particular tree species at Nature Park, Kolkata, India
Autorzy:
Das, A.
Sarkar, S.
Banerjee, K.
Nandy, A.
Talapatra, S.N.
Swarnakar, S.
Powiązania:
https://bibliotekanauki.pl/articles/11152.pdf
Data publikacji:
2014
Wydawca:
Przedsiębiorstwo Wydawnictw Naukowych Darwin / Scientific Publishing House DARWIN
Opis:
The trees support many bird and animal species while the survival of urban-dwelling species e.g. bird species dominate over others. This particular Nature park in Kolkata is the habitat of birds and fish species suggesting a better environment for food chain maintenance. The Asian open bill stork, Anastomus oscitans among other bird species is a common and provides ecosystem health indicator. The present study aims to understand the occurrence and population nos. of Asian open bill stork on particular tree species surrounding wetlands at Nature Park, Kolkata, India. Our results clearly indicate that a total population of this bird species having 671 nos. on the particular trees but not in all other available trees in the study area. In conclusion, present research emphasizes a novel occurrence and higher population of the A. oscitans being observed on the basis of the presence of particular tree species, though no attempt has been made on physico-chemical properties of present water and microclimate within the park. Therefore, further research planning should be oriented considering the physico-chemical impacts as well as local microenvironment along with human interaction as visitors in such a way so that these barriers cannot affect nesting and breeding of those species as eco-indicator. Also further relevant research is needed to emphasize on the conservation of these specific tree species to increase population of Asian open bill stork, A. oscitans in Nature park.
Źródło:
International Letters of Natural Sciences; 2014, 22
2300-9675
Pojawia się w:
International Letters of Natural Sciences
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Seismic and non-seismic soft-sediment deformation structures in the Proterozoic Bhander Limestone, central India
Autorzy:
Sarkar, S.
Choudhuri, A.
Banerjee, S.
Van Loon, A. J.
Bose, P. K.
Powiązania:
https://bibliotekanauki.pl/articles/94668.pdf
Data publikacji:
2014
Wydawca:
Uniwersytet im. Adama Mickiewicza w Poznaniu
Tematy:
seismites
soft-sediment deformation structures
basin subsidence
Proterozoic
India
sejsmity
struktury deformacji
osady miękkie
proterozoik
Indie
Opis:
Numerous soft-sediment deformation structures occur within the Proterozoic Bhander Limestone of an intracratonic sag basin in a 750 m long section along the Thomas River, near Maihar, central India. Part of these deformation structures have most probably a non-seismic origin, but other structures are interpreted as resulting from earthquake-induced shocks. These seismic structures are concentrated in a 60 cm thick interval, which is interpreted as three stacked seismites. These three seismites are traceable over the entire length of the section. They divide the sedimentary succession in a lower part (including the seismites) deposited in a hypersaline lagoon, and an upper open-marine (shelf) part. Most of the soft-sediment deformations outside the seismite interval occur in a lagoonal intraclastic and muddy facies association. The SSDS within the seismite interval show a lateral continuity. They record simultaneous fluidisation and liquefaction. The bases of each of the three composing seismite bands are defined by small-scale shear folds, probably recording an earthquake and aftershocks. The presence of the three seismite bands at the boundary between the lagoonal and the overlying open-marine oolitic facies association suggests that the seismic event also triggered basin subsidence.
Źródło:
Geologos; 2014, 20, 2; 89-103
1426-8981
2080-6574
Pojawia się w:
Geologos
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Performance characteristics of low global warming potential R134a alternative refrigerants in ejector-expansion refrigeration system
Autorzy:
Mishra, S.
Sarkar, J.
Powiązania:
https://bibliotekanauki.pl/articles/240184.pdf
Data publikacji:
2016
Wydawca:
Polska Akademia Nauk. Czytelnia Czasopism PAN
Tematy:
eco-friendly refrigerant
two-phase ejector
optimization
COP
area ratio
critical temperature
ekologiczny czynnik chłodniczy
strumienica dwufazowa
optymalizacja
stosunek powierzchni
temperatura krytyczna
Opis:
Performance assessment of ejector-expansion vapor compression refrigeration system with eco-friendly R134a alternative refrigerants (R152a, R1234yf, R600a, R600, R290, R161, R32, and propylene) is presented for air-conditioning application. Ejector has been modeled by considering experimental data based correlations of component efficiencies to take care of all irreversibilities. Ejector area ratio has been optimized based on maximum coefficient of performance (COP) for typical air-conditioner operating temperatures. Selected refrigerants have been compared based on area ratio, pressure lift ratio, entrainment ratio, COP, COP improvement and volumetric cooling capacity. Effects of normal boiling point and critical point on the performances have been studied as well. Using ejector as an expansion device, maximum improvement in COP is noted in R1234yf (10.1%), which reduces the COP deviation with R134a (4.5% less in basic cycle and 2.5% less in ejector cycle). Hence, R1234yf seems to be best alternative for ejector expansion system due to its mild flammability and comparable volumetric capacity and cooling COP. refrigerant R161 is superior to R134a in terms of both COP and volumetric cooling capacity, although may be restricted for low capacity application due to its flammability.
Źródło:
Archives of Thermodynamics; 2016, 37, 4; 55-72
1231-0956
2083-6023
Pojawia się w:
Archives of Thermodynamics
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Operating characteristics of transcritical CO2 heat pump for simultaneous water cooling and heating
Autorzy:
Sarkar, J.
Bhattacharyya, S.
Powiązania:
https://bibliotekanauki.pl/articles/240930.pdf
Data publikacji:
2012
Wydawca:
Polska Akademia Nauk. Czytelnia Czasopism PAN
Tematy:
charakterystyki pracy
eksperyment
pompa ciepła
symulacja
CO2 heat pump
experiment
performance characteristics
simulation
Water cooling and heating
Opis:
The effects of water-side operating conditions (mass flow rates and inlet temperatures) of both evaporator and gas cooler on the experimental as well as simulated performances (cooling and heating capacities, system coefficient of performance (COP) and water outlet temperatures) of the transcritical CO2 heat pump for simultaneous water cooling and heating the are studied and revised. Study shows that both the water mass flow rate and inlet temperature have significant effect on the system performances. Test results show that the effect of evaporator water mass flow rate on the system performances and water outlet temperatures is more pronounced (COP increases by 0.6 for 1 kg/min) compared to that of gas cooler water mass flow rate (COP increases by 0.4 for 1 kg/min) and the effect of gas cooler water inlet temperature is more significant (COP decreases by 0.48 for given range) compared to that of evaporator water inlet temperature (COP increases by 0.43 for given range). Comparisons of experimental values with simulated results show the maximum deviation of 5% for cooling capacity, 10% for heating capacity and 16% for system COP.
Źródło:
Archives of Thermodynamics; 2012, 33, 4; 23-40
1231-0956
2083-6023
Pojawia się w:
Archives of Thermodynamics
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Effective Pair Interaction from Ab Initio Pseudopotentials - Importance and Applications
Autorzy:
Haldar, S.
Sarkar, A.
Sen, D.
Powiązania:
https://bibliotekanauki.pl/articles/1858123.pdf
Data publikacji:
2000-04
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
63.10.+a
65.90.+i
Opis:
Computation of reliable effective interionic pair interaction for simple metals has been discussed on the basis of localised ab initio pseudopotential within linear screening approximation. The influence of different commonly used screening functions on the shape of pair potential is examined and the temperature dependence of the interaction is also investigated. Various features of the potential are studied and compared with empirical and available first principle results. Importance of the present study and some related problems are also analysed.
Źródło:
Acta Physica Polonica A; 2000, 97, 4; 651-662
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Removal/reduction of organic pollutants from aqueous environment
Usunięcie/redukcja zanieczyszczeń organicznych ze środowiska wodnego
Autorzy:
Sarkar, M.
Das, M.
Manna, S.
Acharya, P.
Powiązania:
https://bibliotekanauki.pl/articles/1826240.pdf
Data publikacji:
2003
Wydawca:
Politechnika Koszalińska. Wydawnictwo Uczelniane
Tematy:
zanieczyszczenia organiczne wody
adsorpcja siarczanu
jakość wody
Opis:
The problem of considerable contamination of the aqueous environment with organic pollutants still requires the development of quick and simple methods for the removal, separation and determination of these compounds. The main classes of organic compounds that most of the industries use and discharge into the effluents are phenol, surfactant and dye. All these compounds are troublesome contaminants which pose not only to toxicity and health hazards but also hamper the environmental treatment processes. In chemical industry phenol is considered as an important starting materials for numerous intermediates and finished products. It is used for the production of a wide range of consumer goods and process materials ranging from adhesives, resins, emulsifiers and detergents, plasticizers, herbicides, dyes and flavors. The worldwide production of phenol is estimated to be 5 million tons per year. Phenol and its analogues are known to be toxic to microbes. The sign of acute illness induced by phenols in experimental animals as well as in humans is known. Continuous ingestion of phenol for a prolonged period of time causes mouth sore, diarrhoea, excretion of dark urine and impaired vision at concentration levels 10÷240 ppm. Lethal blood concentration for phenol is around 1.3 g/L. phenols are toxic to several biochemical functions and to fish life. It acts as a substrate inhibitor in the bio-transformation. World Health Organization (WHO) prescribed a concentration 1 ppb as the guideline concentration in drinking water [1]. Disposal of dyeing industry waste water pose one of the major problem, because such effluents contain a number of contaminants including acid or base, dissolve solids, surfactants and color. Out of these, color is the first contaminant to be recognized because it is visible to human eye. The dye causes the harmful action to various aquatic lives. As it is resistant to light it protects the sunlight from penetrating through it and reduces the aesthetic quality of water. Possible methods of color removal include chemical oxidation, froth flotation, coagulation, adsorption, etc. The anionic surfactants generally are removed by the chemical precipitation, foam separation, ultrafiltration and adsorption. Possible means of removal of phenols from waste water include ion exchange, reverse osmosis, chemical oxidation, precipitation, distillation, gas stripping, solvent extraction, adsorption or bio remediation. Removal of SDS, 4-nitrophenol and malachite green by activated carbon is an efficient and acceptable process. But the cost of operation is very high. Therefore, the present study is undertaken using fly ash as the adsorbent. Compared to activated carbon the efficiency of removal is less in case of 4-nitrophenol and SDS. But fly ash, being a waste material, is very cheap; only the carrying cost from the site of thermal plant to the laboratory is needed. Thus the use of fly ash in removing organic pollutants appears to be a cost viable. The simplicity of the technique makes the process quite acceptable.
Obecność organicznych zanieczyszczeń w strumieniu ścieków znacznie degraduje jakość wody. Zarówno własność estetyczne jaki i organizmy wodne stają wobec niebezpieczeństwa związanego z taką degradacją. Usunięcie zanieczyszczeń organicznych szczególnie za pomącą prostych i tanich metod jest wyzwaniem dla naukowców zajmujących się środowiskiem. Obecnie komunikaty naukowe mówią o możliwości zastosowania popiołów lotnych, odpadów stałych powstających w elektrociepłowniach, w usuwaniu albo redukcji ładunków niektórych organicznych zanieczyszczeń. W referacie przedstawiono wyniki badań nad adsorpcją siarczanu dodecylu sodu SDS (anionowy środek powierzchniowo czynny), zieleni malachitowej MG oraz 4-nitrofenolu na popiołach lotnych. Usunięcie SDS, 4-nitrofenolu i zieleni malachitowej na węglu aktywnym jest skutecznym i zadowalającym procesem. Ale koszt tej operacji jest bardzo wysoki. Dlatego, przedsięwzięto obecne badania używając popiołów lotnych jako substancji adsorbująca. W porównaniu do węgla aktywnego efektywność usunięcia na popiołach lotnych jest mniejsza w przypadku 4-nitrofenolu i SDS. Ale popioły lotne, będąc odpadem, są bardzo tanie. W ten sposób użycie popiołów lotnych w usuwaniu organicznych zanieczyszczeń okazuje się być wykonalne pod względem kosztów. Proces jest wykonalny kinetycznie i termodynamicznie, prosty w wykonaniu i tani.
Źródło:
Rocznik Ochrona Środowiska; 2003, Tom 5; 79-86
1506-218X
Pojawia się w:
Rocznik Ochrona Środowiska
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Static Local Field Factor and Ground State Properties of Interacting Electron Gas
Autorzy:
Sarkar, A.
Haldar, S.
Roy, D.
Sen, D.
Powiązania:
https://bibliotekanauki.pl/articles/2038378.pdf
Data publikacji:
2004-10
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
71.10.-w
71.45.Gm
Opis:
In the most general case, the calculation of the static local field factor G(q) for the unpolarised electron gas requires the knowledge of exchange-correlation energy functionals for both the parallel and antiparallel relative spin orientations of the electron gas system. Accurate density interpolation formulae using the quantum Monte Carlo data of Ceperley-Alder for the correlation energy of electron gas in both the "para" and "ferro" states, respectively, in the given density range are used for the calculation of G( q). Fulfilment of relevant consistency criteria is ensured and the local field factor so obtained renders significant improvement of ab initio pseudopotential calculation of effective interaction of Al. The Levin like interpolant of the correlation energy Ceperley-Alder data has been further used to study the ground state properties of the electron gas. It is also noted that a better understanding of the interacting electron gas properties requires a more accurate spin interpolation formula for the correlation energy than the existing ones.
Źródło:
Acta Physica Polonica A; 2004, 106, 4; 497-514
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Sodium carbonate pre-extraction of Trema orientalis in the production of paper grade pulp
Autorzy:
Jahan, M.S.
Sarkar, M.
Rahman, M.M.
Powiązania:
https://bibliotekanauki.pl/articles/52662.pdf
Data publikacji:
2015
Wydawca:
Sieć Badawcza Łukasiewicz - Instytut Technologii Drewna
Tematy:
sodium carbonate
alkaline pre-extraction
Trema orientalis
production
paper pulp
dissolved biomass
pulping
bleaching
paper property
paper industry
pulp industry
Opis:
To increase the profitability of the pulp and paper industry, additional value added products from lignocelluloses are needed, and consistent with this goal, a biorefinery concept based on the sodium carbonate pre-extraction of Trema orientalis prior to pulping was proposed. The solid content in the sodium carbonate pre-extracted liquor was much lower than the hot water pre-extraction, which affected the pre-hydrolysis yield and overall pulp yield positively. The alkaline pre-extraction had a beneficial effect on delignification in the subsequent soda-AQ-pulping. In addition, the alkaline pre-extraction improved the pulp bleachability. The papermaking properties of the alkaline pre-extracted soda-AQ pulp were very close to non-extracted pulp after D0EpD1 bleaching.
Źródło:
Drewno. Prace Naukowe. Doniesienia. Komunikaty; 2015, 58, 195
1644-3985
Pojawia się w:
Drewno. Prace Naukowe. Doniesienia. Komunikaty
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Assessment of viable fungi in indoor air: a case study from Tagore’s residence at Jorasanko, India
Autorzy:
Bhattacharyya, S.
Mukherjee, D.
Sarkar, P.
Ghosh, S.
Samaddar, B.
Chaudhuri, P.
Powiązania:
https://bibliotekanauki.pl/articles/11560.pdf
Data publikacji:
2015
Wydawca:
Przedsiębiorstwo Wydawnictw Naukowych Darwin / Scientific Publishing House DARWIN
Tematy:
assessment
viable fungi
fungi
indoor air
indoor environment
Tagore’s residence
Jorasanko
India
Opis:
Indoor environment is significant with respect to human health especially if it is concerned when the building is v. Aim of very old. In the present study was to assess the presence of airborne fungi at an old building in Kolkata India where lots of tourists are exposed every day. Residence of famous Nobel laureate poet Rabindranath Tagore (built in the 18th century and presently used as a famous museum) in Kolkata, West Bengal was selected for this study and the indoor fungi from different room of the museum were assessed by using exposure plate technique. Humidity, temperature, wind speed and illuminance were also measured by hygrometer, thermometer anemometer and lux-meter respectively. The fungal species isolated from the air samples of different rooms were Aspergillus sp., Penicillium sp., Paecilomyces sp., Trichoderma sp, Alternaria sp Verticillium sp, Fusarium sp, Cladosporium sp, Yeast, Curvularia sp. and Helminthosporium sp. among them, Aspergillus sp. (71.4% at monsoon at library), Penicillium sp (57% at summer at library), Paecilomyces sp.(91% at monsoon at manuscript room) are mostly dominated pathogens, which may harm the workers and visitors of the museum. No significant correlation among colony forming unit of fungi with illuminance, wind speed and temperature in the tested indoor environment was noted whereas, the humidity in indoor environment played a crucial (P<0.05) role. Round the year humidity control may be required for maintaining healthy environment.
Źródło:
International Letters of Natural Sciences; 2015, 06
2300-9675
Pojawia się w:
International Letters of Natural Sciences
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Impact of geoenvironmental hazards on ground water and human health: the mechanism and management
Wpływ geośrodowiskowych zagrożeń na wody gruntowe i zdrowie ludzkie: mechanizm i zarządzanie
Autorzy:
Sarkar, M.
Manna, S.
Banerjee, A.
Pramanick, P. P.
Powiązania:
https://bibliotekanauki.pl/articles/1826184.pdf
Data publikacji:
2004
Wydawca:
Politechnika Koszalińska. Wydawnictwo Uczelniane
Tematy:
wody gruntowe
zagrożenia geośrodowiskowe
zanieczyszczenie wód guntowych
Opis:
Management and protection of the ground water is most important, since ground water is considered as the most precious resource in the earth. Once this vital resource is contaminated it will cause several ecological disturbances. In recent years the large-scale occurrence of ground water contamination by some inorganic pollutants like arsenic and fluoride and the associated human sufferings is a threat of this millennium. The severity, magnitude and spread of such problem over the world have reached at an alarming stage (1,2). The source of contamination of ground water is primarily geogenic in origin, with some anthropogenic activities accelerating the problem. The actual mechanism of leaching of the contaminants from the parent minerals to the aquifers is not understood. Still it is clear that indiscriminate use of ground water definitely aggravate the problem. It is estimated that at least sixty four million people in the world are suffering from fluoride related health problem (3) and more than four million people in India, in the state of West Bengal alone (4) are developed the symptom of arsenic toxicity. Both arsenic and fluoride are widely distributed throughout the earth's crust and are introduced into ground water through the dissolution of minerals and ores as well as a result of erosion from local rocks. Industrial effluents also contribute arsenic and fluoride to water in some areas. Arsenic and fluoride are also used commercially, e.g., in alloying agents and wood preservatives. Combustion of fossil fuels is a source of the contaminations in the environment through disperses atmospheric deposition. Arsenic and fluoride from water, sediment, soil and rocks can concentrate in living organisms. Among the different sources of contaminations the pollution of ground water through geological sources are very crucial. The complex pathway and mobilization pattern make the situation very critical. Fluoride and Arsenic poisoning can be prevented or at least minimized by use of alternative water sources and treated water after removal of fluoride and arsenic. Surface water, rainwater and fluoride/arsenic free ground water can be considered as alternative water sources. Among the conventional removal techniques precipitation, adsorption, ion exchange, electrolysis and reverse osmosis can be used. In our laboratory we tested some low cost waste material (viz. fly ash from thermal power plant) and natural material (laterite, the widely available clay in India) for the removal of arsenic and fluoride from contaminated drinking water.
Ostatnie sprawozdania pokazują, że około 26 krajów jest dotkniętych problemem zanieczyszczenia wód gruntowych arsenem, wśród których cztery kraje południowo azjatyckie: Bangladesz, Indie (Zachodni Bengal), Chiny i Tajwan są najbardziej zagrożone. Obecnie w 29 krajach na świecie występuje problem zanieczyszczenia wód gruntowych fluorem pochodzącym tylko ze źródeł geośrodowiskowych. Wpływ na zdrowie przypadku obu tych zanieczyszczeń jest bardzo poważny, a skutki są nieodwracalne i praktycznie nie istnieje żadna kuracji mogąca wyleczyć zakażone osoby. W Indiach bardzo duża populacja cierpi z powodu zatrucia arsenem i fluorem. Ostatnie badania przeprowadzone przez UNICEF wskazują, że co najmniej 213 okręgów w 18 stanach (w tym cztery okręgi Zachodniego Bengalu), jest dotknięte tym problemem. Skala problemu zanieczyszczenia arsenem w Zachodnim Bengalu jest bardzo poważna w dziewięciu okręgach z pośród osiemnastu. Średnia wysokiego stężenia arsenu jest 4,5 razy przekracza wartość tolerowaną przez ludzkie ciało (0,05 mg/L, norma w Indiach). W niektórych miejscach wartość ta przekroczona jest nawet siedmiokrotnie. Najwyższe oznaczone stężenie fluoru w wodzie gruntowej w Zachodnim Bengalu wynosiło 19 mg/L (maksymalna dopuszczalna wartość wg WHO to 0,5 mg/). Największe stężenie fluoru w wodzie gruntowej w Indiach oznaczono w miejscowości Haryana i wynosiło ponad 84 mg/L. Nasze badania we wsiach Nashipur, Bhabanandapur, Nowapara, Chakatla, Junidpur w dzielnicy Rampurhat, okręgu Birbhum, Zachodni Bengal pokazują największe stężenie fluoru wynoszące 16,0 mg/L (prawie 16 razy większe niż granicę dopuszczalną przez WHO). Na terenie badań prawie 90% dzieci w grupie wiekowej poniżej 15 lat posiada rozwinięte symptom fluorozy dentystycznej. W typowych badaniach około 21 000 próbek włosów, paznokci, naskórka i moczu (tylko metabolity arsenu zostały zmierzone) mieszkańców terenów skażonych arsenem zostało zanalizowanych na zawartość arsenu. Około 10÷15% z tych próbek pochodzi od ludzi mających uszkodzenia skóry spowodowane przez arsen. 56%, 80% i 87% z analizowanych próbek zawiera arsen we włosach, paznokciach i moczu w ilościach przekraczających poziom normalnym / toksyczny (włosy).
Źródło:
Rocznik Ochrona Środowiska; 2004, Tom 6; 51-62
1506-218X
Pojawia się w:
Rocznik Ochrona Środowiska
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Socio-Environmental survey of an ecologically important forest edge hamlet in Buxa Tiger Reserve, West Bengal, India
Autorzy:
Bhattacharya, S.
Maity, R.
Sarkar, G.
Ghosh, G.
Mukherjee, D.
Mukhopadhyay, C.
Powiązania:
https://bibliotekanauki.pl/articles/11301.pdf
Data publikacji:
2016
Wydawca:
Przedsiębiorstwo Wydawnictw Naukowych Darwin / Scientific Publishing House DARWIN
Opis:
Buxa Tiger Reserve (BTR) is located in Alipurduar Sub Division of West Bengal, India. It comprises of the entire forest area of the erstwhile Buxa Forest Division (Created in 1877 – 78) and some territory of the erstwhile neighboring Cooch Behar Forest Division. The Reserve lies between Latitudes 23o30′ N to 23o50′ N and Longitudes 89o25′ E to 89o55′ E. The total area of the reserve is 760.87 km2 of which 385.02 km2 has been constituted as the Buxa Sanctuary and National Park (Core zone of the BTR) and the balance 375.85 km2 areas is treated as a buffer zone. It has 37 forest villages and 4 fixed demand holdings, 46 revenue villages and 34 tea gardens in and around it. The survey work was done in May, 2015 by visiting a forest edge village, 28 Mile, in Buxa Tiger Reserve and the primary data were gathered through field survey and direct contact with common people and authorized centres of the region. Surveys on the demography, agriculture, livestock management, water management, education, culture, health, waste management, disaster management, transport, biodiversity, joint forest management activities, Non-timber forest product usage and human animal conflict were done in this area. In every phase of the survey work, photographic documentation was done. In spite of being positioned in a diverse and sensitive ecological zone, the village is not adequately managed. There is an urgent need for implementing sustainable management systems in the areas for the betterment of the socio-environmental structures. Some of the possible management strategies have been suggested for maintaining the social, environmental, economic and ecological balance of the region.
Źródło:
International Letters of Natural Sciences; 2016, 52
2300-9675
Pojawia się w:
International Letters of Natural Sciences
Dostawca treści:
Biblioteka Nauki
Artykuł
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