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Wyświetlanie 1-19 z 19
Tytuł:
Can physical training minimize the gender differences in lung capacity of trained tennis players aged 14-17 years old?
Autorzy:
Pandit, N.
Banik, S.
Prasad, S.K.
Majumdar, P.
Banerjee, O.
Bandyopadhyay, A.
Powiązania:
https://bibliotekanauki.pl/articles/1795.pdf
Data publikacji:
2018
Wydawca:
Uniwersytet Opolski. Instytut Nauk o Zdrowiu
Tematy:
male
female
lung capacity
sport
tennis player
gender difference
physical training
tennis
Opis:
Background: This study was based on gender differences in male and female trained tennis players. Aim of the study: The aim of this study was to determine the extent that physical training could minimize the gender differences in lung capacities in trained tennis players aged 14–17 years. Material and methods: The participants were ten male and seven female lawn tennis players, with a mean ± standard deviation (SD) age of 15.5 ± 1.27 and 14.43 ± 1.13 years, respectively. Physical characteristics and lung volumes were measured on the same day for each participant. Data were presented as mean ± SD, and Student’s t-test to compare the measured variables was performed. Results: Differences between genders were insignificant in terms of age (years), weight (kg), body fat (%), lean body mass (kg) and chest circumference (cm). However, height (cm), and W/H ratio were significantly (p < 0.05) higher in male tennis players in comparison to female players. Insignificant differences were found for TV (L), SVC (L), FVC (L), FEV1 (L), FEV1/FVC (%), FEF25-75% (L/s), PEF (L/s) and MVV (L/min). The only significant difference (p < 0.05) in lung function measures between male and female trained tennis players was for PIF (L/s). Conclusions: Male tennis players were taller than female tennis players of same age range, which might be advantageous for males while playing. Insignificant differences between male and female players in the various lung variables measured indicated that the influence of height and gender differences could be minimized by proper training during puberty. A significantly higher PIF in male players indicated stronger and more powerful inspiratory muscle activity compared with female tennis players.
Źródło:
Medical Science Pulse; 2018, 12, 2
2544-1558
2544-1620
Pojawia się w:
Medical Science Pulse
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Erythrocyte functional status and lipid profile of coal mine workers of West Bengal, India
Autorzy:
Prasad, S.K.
Bhattacharjee, A.
Bandyopadhyay, P.
Pal, S.
Syamal, A.K.
Mukherjee, S.
Powiązania:
https://bibliotekanauki.pl/articles/1916566.pdf
Data publikacji:
2014
Wydawca:
Uniwersytet Medyczny w Białymstoku
Tematy:
Coal miners
antioxidant insufficiency
blood lipid profiles
erythrocyte osmotic fragility
oxidative stress
Opis:
Purpose: Despite people suffering from several forms of ill health, constant exposure to toxic wastes and chronic diseases as a result of mining, there is a tragic gap in the availability of ‘scientific’ studies and data on the health hazards of mining in India. This study was proposed to understand better the relationship between occupational exposure to coal, blood lipid profiles and red blood cell (RBC) functional status of coal workers. Materials and methods: Blood samples were obtained from coal miners (n=32) of an underground mine in West Bengal. Blood lipid profiles and RBC functional status were determined. Students’ t-test and Pearson correlation analyses were completed to analyze the data. Results: Compared to the control subjects, significantly higher levels of cholesterol (p<0.01), triglycerides (p<0.01), LDL (p<0.001), and VLDL (p<0.001) were observed in coal miners. HDL, Hb, Na+-K+ATPase and SOD activity were significantly (p<0.001) lower in coal miners, whereas MDA levels (p<0.001) and osmotic fragility in coal miners were increased significantly (p<0.01). Conclusions: Our study indicates that elevated MDA and antioxidant insufficiency caused disruption in the structural integrity of erythrocyte, which may be a pathophysiological mechanism in the progression of disease in coal miners. Also, cardiovascular disease risk factors were more prevalent in the coal miners.
Źródło:
Progress in Health Sciences; 2014, 4, 2; 14-21
2083-1617
Pojawia się w:
Progress in Health Sciences
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Geochemistry and Tectonic Environments of Aphibolites Bethampudi Anorthosite Complex, Khammam Schist Belt, Telangana, India
Autorzy:
Brahmaiah, T.
Ravi, Ch.
Basha, U. Imran
Prasad, K. S. Sai
Powiązania:
https://bibliotekanauki.pl/articles/1075430.pdf
Data publikacji:
2019
Wydawca:
Przedsiębiorstwo Wydawnictw Naukowych Darwin / Scientific Publishing House DARWIN
Tematy:
E-MORB and Subduction zone
Geochemistry and Tectonic Environments
MORB
N-MORB
Tholeiitic
Opis:
The Bethampudi anorthosite complex is essentially a leucograbbro (gabboric anorthosite and anorthositic gabbro), anorthosites, amphibolites, and pegmatite occur as concordant or discordent bodies. This work involves detailed geological geochemical investigations of amphibolites so as to reveal their possible protolith. The field relaltions, major, trace and rare earth element compositions of ampbibolites suggest that they are petrogenetically related to anorthosites by fractional crystallisation. Protoliths of the amphibolites show a tholeiitic signature that prevails over the sub-alkaline nature and E-MORB affinities. They were generated from a depleted mantle surface with the influence of a subduction and within-plate components.
Źródło:
World Scientific News; 2019, 126; 65-87
2392-2192
Pojawia się w:
World Scientific News
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Identification of volatile organic compound producing Lignicolous fungal cultures from Gujarat, India
Autorzy:
Nagadesi, Praveen Kumar
Arya, Arun
Babu, Duvvi Naveen
Prasad, K. S. M.
Devi, P. P.
Powiązania:
https://bibliotekanauki.pl/articles/1178801.pdf
Data publikacji:
2017
Wydawca:
Przedsiębiorstwo Wydawnictw Naukowych Darwin / Scientific Publishing House DARWIN
Tematy:
India
Lenzites sterioides
Lignicolous fungi
Volatile organic compound (VOC)
Opis:
This study aims to identify the lignicolous basidiomycetes species that synthetize volatile organic compounds with potential applications in food industry, cosmetics, perfumery and agriculture. We have collected fruiting bodies from different woody plants and the lignicolous basidiomyctes species were identified by their macroscopic and microscopic characteristics. From the context of the fresh fruiting bodies small fragments of dikaryotic mycelium were extracted and inoculated on PDA and MEA media for isolation and pure cultures are kept in dark at a temperature of 25°C. 11 species of lignicolous basidiomycetes, belonging to 6 families and 5 orders were isolated in pure culture. The isolates were analyzed in vitro and the main characteristics that were observed are: the general aspect of the surface and the reverse of the colonies, the changing in colour and the growth rate of the mycelium and also the specific odour which indicates the presence of the organic volatile compounds. for the first time lignicolous fungi like Flavodon flavus (Klotz.) Ryv., Ganoderma lucidum(Curtis) P. Karst, Hexagonia apiaria (Pers.) Fr., Lenzites betulina (L.) Fr. Lenzites eximia Berk. & M.A. Curtis, Lenzites sterioides (Fr.) Ryv., Navisporus floccosus (Bres.) Ryv., Phellinus gilvus (Schwein.) Pat., and Trametes pini (Thore) Britzelm. were producing characteristic smell that indicates presence of Volatile organic compounds. For the first time from Gujarat, India the Volatile organic compound producing fungi were identified and their culture characters also described.
Źródło:
World Scientific News; 2017, 90; 150-165
2392-2192
Pojawia się w:
World Scientific News
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Toxicity of bisphenol a on humans: a review
Autorzy:
Preethi, S.
Sandhya, K.
Lebonah, D.E.
Prasad, Ch.V.
Sreedevi, B.
Chandrasekhar, K.
Kumari, J.P.
Powiązania:
https://bibliotekanauki.pl/articles/11618.pdf
Data publikacji:
2014
Wydawca:
Przedsiębiorstwo Wydawnictw Naukowych Darwin / Scientific Publishing House DARWIN
Opis:
Bisphenol A (BPA) is a plastic ingredient produced in large quantities for use primarily in the production of polycarbonate plastics and epoxy resins. The present review focused on different mechanisms of BPA on human health in enzymatic, androgenic, neurological, liver and reproductive systems. The review explained the influence of BPA on different stages of human life likely in foetal stage, children and adults stages. The review also concentrated on how to handle BPA, treatment, preventive measures against BPA exposure.
Źródło:
International Letters of Natural Sciences; 2014, 22
2300-9675
Pojawia się w:
International Letters of Natural Sciences
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Variation of Electrical Resistivity with High Pressure in Ge-Te-Sn Glasses: A Composition Dependent Study
Autorzy:
Prasad, K.
Das, Chandasree
Rukmani, K.
Asokan, S.
Powiązania:
https://bibliotekanauki.pl/articles/1400510.pdf
Data publikacji:
2015-06
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
72.80.Ng
Opis:
The variation of normalized electrical resistivity in the system of glasses $Ge_{15}Te_{85-x}Sn_{x}$ with (1 ≤ x ≤ 5) has been studied as a function of high pressure for pressures up to 9.5 GPa. It is found that with the increase in pressure, the resistivity decreases initially and shows an abrupt fall at a particular pressure, indicating the phase transition from semiconductor to near metallic at these pressures, which lie in the range 1.5-2.5 GPa, and then continues being metallic up to 9.5 GPa. This transition pressure is seen to decrease with the increase in the percentage content of tin due to increasing metallicity of tin. The semiconductor to near metallic transition is exactly reversible and may have its origin in a reduction of the band gap due to high pressure.
Źródło:
Acta Physica Polonica A; 2015, 127, 6; 1666-1671
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Mass transfer analysis of two-phase flow in a suspension of microorganisms
Autorzy:
Mamatha, S.U.
Ramesh, Babu, K.
Durga Prasad, Putta
Raju, C.S.K.
Varma, S.V.K.
Powiązania:
https://bibliotekanauki.pl/articles/240799.pdf
Data publikacji:
2020
Wydawca:
Polska Akademia Nauk. Czytelnia Czasopism PAN
Tematy:
gyrotactic microorganisms
dusty fluid
mass transfer
stretching sheet
bio convection
boundary layer flow
Opis:
The aim of present work is to investigate the mass transfer of steady incompressible hydromagnetic fluid near the stagnation point with deferment of dust particles over a stretching surface. Most researchers tried to improve the mass transfer by inclusion of cross-diffusion or dust particles due to their vast applications in industrial processes, extrusion process, chemical processing, manufacturing of various types of liquid drinks and in various engineering treatments. To encourage the mass transport phenomena in this study we incorporated dust with microorganisms. Conservation of mass, momentum, concentration and density of microorganisms are used in relevant flow equations. The arising system of nonlinear partial differential equations is transformed into nonlinear ordinary differential equations. The numerical solutions are obtained by the Runge-Kutta based shooting technique and the local Sherwood number is computed for various values of the physical governing parameters (Lewis number, Peclet number, Eckert number). An important finding of present work is that larger values of these parameters encourage the mass transfer rate, and the motile organisms density profiles are augmented with the larger values of fluid particle interaction parameter with reference to bioconvection, bioconvection Lewis number, and dust particle concentration parameter..
Źródło:
Archives of Thermodynamics; 2020, 41, 1; 175-192
1231-0956
2083-6023
Pojawia się w:
Archives of Thermodynamics
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
An investigation into the effect of rockmass properties on mean fragmentation
Autorzy:
Chandrahas, Sri
Choudhary, Bhanwar Singh
Prasad, N. S. R. Krishna
Musunuri, Venkataramayya
Rao, K. K.
Powiązania:
https://bibliotekanauki.pl/articles/2073876.pdf
Data publikacji:
2021
Wydawca:
Polska Akademia Nauk. Czytelnia Czasopism PAN
Tematy:
górotwór
test wytrzymałości
kopalnia węgla
Opis:
Desired rock fragmentation is the need of the hour, which influences the entire mining cycle. Thus, most engineering segments pay attention to rock fragmentation and neglect by-products like ground vibration and fly rock. Structural and mechanical properties of rock mass like joint spacing, joint angle, and compressive strength of rock pose a puzzling impact on both fragmentation and ground vibration. About 80% of explosive energy that gets wasted in producing ill effects can be positively optimised, with a new set of blast design parameters upon identifying the behaviour of rock mass properties. In this connection, this research aims to investigate the influence of joint spacing, joint angle, and compressive strength of rock on fragmentation and induced ground vibration. To accomplish this task, research was carried out at an opencast coal mine. It was discovered from this research that compressive strength, joint spacing, and joint angle have a significant effect on the mean fragmentation size (MFS) and peak particle velocity (PPV). With the increase in compressive strength, MFS explicit both increase and decrease trends whilst PPV increased with a specific increase in compressive strength of the rock. An increase in joint spacing triggers both increase and decrease trends in both MFS and PPV. While there is an increase in joint angle, MFS and PPV decrease.
Źródło:
Archives of Mining Sciences; 2021, 66, 4; 561--578
0860-7001
Pojawia się w:
Archives of Mining Sciences
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
On a method to employ Newton’s Rings concept to determine thickness of thin films
Autorzy:
Raveesha, K. H.
Doddamani, V. H.
Prasad, B. K.
Powiązania:
https://bibliotekanauki.pl/articles/412571.pdf
Data publikacji:
2014
Wydawca:
Przedsiębiorstwo Wydawnictw Naukowych Darwin / Scientific Publishing House DARWIN
Tematy:
Interference
fringes
destructive interference
constructive interference
air wedle
Opis:
Newton’s Rings experiment is traditionally utilized to find radius curvature of a lens. We propose a method in which this same set up can be used to find the thickness of thin films. The working principle is interference. It is based on the fact that, the formation of bright and dark interference fringes is a measure of the thickness of the air film at that point. We present the experimental data. The results from the experiment are in agreement with results obtained through geometry. Further, a method to improvise conventional interference at air wedge experiment which is generally used to determine the thickness of thin films is suggested.
Źródło:
International Letters of Chemistry, Physics and Astronomy; 2014, 3; 1-7
2299-3843
Pojawia się w:
International Letters of Chemistry, Physics and Astronomy
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Studies on Tungsten Based High Density Cast Polymer Bonded Explosive (PBX) Formulations
Autorzy:
Vadhe, P. P.
Manickam, S.
Rahujade, N.
Kondra, A.
Prasad, U.
Sinha, R. K.
Powiązania:
https://bibliotekanauki.pl/articles/358080.pdf
Data publikacji:
2015
Wydawca:
Sieć Badawcza Łukasiewicz - Instytut Przemysłu Organicznego
Tematy:
tungsten
RDX
HMX
HTPB
PBX
Opis:
Aluminized melt-cast TNT and PBX (cast/pressed) based compositions have been widely studied and used in different warheads for various applications,such as air blast, underwater blast, thermobaric effects, etc. Tungsten (W) based cast PBX formulations are the least reported in the literature. We have partially replaced RDX or HMX in the control PBX formulation with 15 to 25% W powder and investigated the effect of this on the ease of processing, density, sensitivity, mechanical properties and explosive performance. The viscosity was improved from 9 to 3 kPoise, and the density by about 12 to 25% on the addition of W powder to the PBX formulations. The sensitivity to impact for the RDX/Wand HMX/W based PBX formulations was improved by 12 to 37%. The reinforcing effect of the W powder caused an increase in hardness (Shore A) by 16 to 45%. A decreasing trend in the velocity of detonation (VOD) was observed because of the replacement of the nitramine content (RDX/HMX) with W powder. The approximate detonation pressure of RDX/W/HTPB (65/20/15), roughly calculated by the Kamlet-Jacobs method, is better than the other tungsten based formulations investigated.
Źródło:
Central European Journal of Energetic Materials; 2015, 12, 3; 497-506
1733-7178
Pojawia się w:
Central European Journal of Energetic Materials
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Synthesis and Characterization of an Efficient New Liquid Laser Dye Material - Chalcone (DMAPPP)
Autorzy:
Elzupir, A.
Ibnaouf, K.
Idriss, H.
Ibrahem, M.
Prasad, S.
Alrajhi, M.
AlSalhi, M.
Alaamer, A.
Powiązania:
https://bibliotekanauki.pl/articles/1030569.pdf
Data publikacji:
2018-01
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
chalcone
DMAPPP
solvents effect
fluorescence
ASE
Opis:
This paper comprises the synthesis and characterization of 3-(4-(dimethylamino)phenyl)-1-phenyl-(2E)-propen-1-one (DMAPPP) and its application as a new laser medium. The absorption and fluorescence spectra of DMAPPP under different solvents and concentrations have been investigated. The amplified spontaneous emission performance of DMAPPP under various concentrations, organic solvents and pump pulse energies of Nd:YAG laser (355 nm) was also studied. The amplified spontaneous emission spectra of DMAPPP in solution were compared with a conventional laser dye of coumarin 503, under the same identical conditions. The gain and the fluorescence quantum yield of DMAPPP were determined. The most important features are: (1) DMAPPP has an excellent photochemical stability, (2) the amplified spontaneous emission from the DMAPPP was tuned in the wavelength region between 515 and 548 nm. This could be the first detailed paper on laser properties of DMAPPP.
Źródło:
Acta Physica Polonica A; 2018, 133, 1; 121-125
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Optimization and production of alkaline proteases from agro byproducts using a novel Trichoderma viridiae strain VPG 12, isolated from agro soil
Autorzy:
Shivasharanappa, K.
Hanchinalmath, J.V.
Sundeep, Y.S.
Borah, D.
Prasad Talluri, V.S.S.L.
Powiązania:
https://bibliotekanauki.pl/articles/11791.pdf
Data publikacji:
2014
Wydawca:
Przedsiębiorstwo Wydawnictw Naukowych Darwin / Scientific Publishing House DARWIN
Tematy:
optimization
production
alkaline protease
agricultural product
Trichoderma viride
agricultural soil
fermentation process
red gram husk
substrate
Opis:
In recent years, there has been a phenomenal increase in the use of alkaline proteases as industrial catalysts. The aim of this work was to isolate potent fungal strain from the agricultural field of Gulbarga region of India, for the production of alkaline protease by utilizing the agricultural by products viz, red and green gram and Bengal gram as substrate under submerged fermentation process. Optimization of fermentation process parameters such as substrate (Red gram husk, green gram husk and Bengal gram husk) utilization, utilization, temperature, pH and incubation period for alkaline protease production was carried out. The maximum production of alkaline protease by Trichoderma VPG 12 was found at pH 8, temperature 35 °C, incubated for 120 h. But the activity of the enzyme could also be seen in a wide range of pH (5-9) and temperature (20-40 °C). With all these properties, the strain can be considered for industrial grade production of alkaline protease.
Źródło:
International Letters of Natural Sciences; 2014, 09
2300-9675
Pojawia się w:
International Letters of Natural Sciences
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Experimental investigation to study the viscosity and dispersion of conductive and non-conductive nanopowders’ blended dielectrics
Autorzy:
Santarao, K.
Prasad, C. L. V. R. S. V.
Swami Naidu, G.
Powiązania:
https://bibliotekanauki.pl/articles/102844.pdf
Data publikacji:
2017
Wydawca:
Stowarzyszenie Inżynierów i Techników Mechaników Polskich
Tematy:
nanofluid
viscosity
dispersion
sonication
silicon carbide nano powder
boric acid nano powder
Opis:
Nano fluids are nanotechnology-based colloidal dispersions engineered by stably suspending nanoparticles. The characteristics of nano fluids such as thermal and electrical conductivities, viscosity, specific heat, dispersion etc. were studied and analyzed by earlier researches at different particle concentrations with different nano fluids. It was established that nano fluids have a significant impact on the process due the improvised characteristics. Nano fluid viscosity and dispersion deserve the same attention as thermal conductivity in cases of nano dielectric fluids that are used in EDM as they influence the MRR. In this work, The viscosity and dispersion of the conductive and nonconductive Nano powders blended dielectrics are investigated as a function of volume fraction so as to evaluate the behavior of these nano fluids at different particle volume concentrations. Kerosene and deionized water based nano fluids blended with conductive (SiC) and non-conductive (boric acid) Nano particles are selected for the current study. It is observed that as the percentage volume fraction of nano particles (both SiC and boric acid) increased, the viscosity was found increasing when blended with DI water. But the viscosity behavior with kerosene blended with SiC and boric acid is not same. The existing experimental results about the nano fluids viscosity shows clearly that viscosity have a specific trend in variation with an increase of volume concentration. Boric acid blended with DIW and kerosene shows similar trend in dispersion. However, in case of SiC blended with DIW and kerosene showed some contradictory results giving scope for further investigation. The outcome of these experimental investigations will augment the works that are going on in studying its influence on MRR in EDM processes using nano blended dielectric medium.
Źródło:
Advances in Science and Technology. Research Journal; 2017, 11, 1; 154-160
2299-8624
Pojawia się w:
Advances in Science and Technology. Research Journal
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Lung cancer detection using an integration of fuzzy K-Means clustering and deep learning techniques for CT lung images
Autorzy:
Prasad, J. Maruthi Nagendra
Chakravarty, S.
Krishna, M. Vamsi
Powiązania:
https://bibliotekanauki.pl/articles/2173683.pdf
Data publikacji:
2022
Wydawca:
Polska Akademia Nauk. Czytelnia Czasopism PAN
Tematy:
fuzzy K-means
artificial neural networks
SVM
support vector machine
crow search optimization algorithm
algorytm rozmytych k-średnich
sztuczne sieci neuronowe
maszyna wektorów wspierających
algorytm optymalizacji wyszukiwania kruków
Opis:
Computer aided detection systems are used for the provision of second opinion during lung cancer diagnosis. For early-stage detection and treatment false positive reduction stage also plays a vital role. The main motive of this research is to propose a method for lung cancer segmentation. In recent years, lung cancer detection and segmentation of tumors is considered one of the most important steps in the surgical planning and medication preparations. It is very difficult for the researchers to detect the tumor area from the CT (computed tomography) images. The proposed system segments lungs and classify the images into normal and abnormal and consists of two phases, The first phase will be made up of various stages like pre-processing, feature extraction, feature selection, classification and finally, segmentation of the tumor. Input CT image is sent through the pre-processing phase where noise removal will be taken care of and then texture features are extracted from the pre-processed image, and in the next stage features will be selected by making use of crow search optimization algorithm, later artificial neural network is used for the classification of the normal lung images from abnormal images. Finally, abnormal images will be processed through the fuzzy K-means algorithm for segmenting the tumors separately. In the second phase, SVM classifier is used for the reduction of false positives. The proposed system delivers accuracy of 96%, 100% specificity and sensitivity of 99% and it reduces false positives. Experimental results shows that the system outperforms many other systems in the literature in terms of sensitivity, specificity, and accuracy. There is a great tradeoff between effectiveness and efficiency and the proposed system also saves computation time. The work shows that the proposed system which is formed by the integration of fuzzy K-means clustering and deep learning technique is simple yet powerful and was effective in reducing false positives and segments tumors and perform classification and delivers better performance when compared to other strategies in the literature, and this system is giving accurate decision when compared to human doctor’s decision.
Źródło:
Bulletin of the Polish Academy of Sciences. Technical Sciences; 2022, 70, 3; art. no. e139006
0239-7528
Pojawia się w:
Bulletin of the Polish Academy of Sciences. Technical Sciences
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Entropy analysis of third-grade MHD convection flows from a horizontal cylinder with slip
Autorzy:
Madhavi, K.
Prasad, V. R.
Gaffar, S. A.
Venkatadri, K.
Powiązania:
https://bibliotekanauki.pl/articles/139843.pdf
Data publikacji:
2018
Wydawca:
Polska Akademia Nauk. Czytelnia Czasopism PAN
Tematy:
third-grade viscoelastic fluid model
thermal jump
entropy generation
Bejan number
Hartmann number
lepkosprężysty model cieczy trzeciego stopnia
skok termiczny
generowanie entropii
liczba Bejana
liczba Hartmanna
Opis:
In thermos fluid dynamics, free convection flows external to different geometries, such as cylinders, ellipses, spheres, curved walls, wavy plates, cones, etc., play major role in various industrial and process engineering systems. The thermal buoyancy force associated with natural convection flows can play a critical role in determining skin friction and heat transfer rates at the boundary. In thermal engineering, natural convection flows from cylindrical bodies has gained exceptional interest. In this article, we mathematically evaluate an entropy analysis of magnetohydrodynamic third-grade convection flows from permeable cylinder considering velocity and thermal slip effects. The resulting non-linear coupled partial differential conservation equations with associated boundary conditions are solved with an efficient unconditionally stable implicit finite difference Keller-Box technique. The impacts of momentum and heat transport coefficients, entropy generation and Bejan number are computed for several values of non-dimensional parameters arising in the flow equations. Streamlines are plotted to analyze the heat transport process in a two-dimensional domain. Furthermore, the deviations of the flow variables are compared with those computed for a Newtonian fluid and this has important implications in industrial thermal material processing operations, aviation technology, different enterprises, energy systems and thermal enhancement of industrial flow processes.
Źródło:
Archive of Mechanical Engineering; 2018, LXV, 3; 417-440
0004-0738
Pojawia się w:
Archive of Mechanical Engineering
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Axisymmetric mixed convective MHD flow over a slender cylinder in the presence of chemically reaction
Autorzy:
Prasad, K. V.
Vaidya, H.
Vajravelu, K.
Datti, P. S.
Umesh, V.
Powiązania:
https://bibliotekanauki.pl/articles/264807.pdf
Data publikacji:
2016
Wydawca:
Uniwersytet Zielonogórski. Oficyna Wydawnicza
Tematy:
pole magnetyczne
reakcja chemiczna
przepływ konwekcyjny
metoda Keller-box
Keller-box method
Grashof number
slender cylinder
convective flow
magnetic field
chemical reaction
heat and mass transfer
Opis:
The present analysis is focused on the study of the magnetic effect on coupled heat and mass transfer by mixed convection boundary layer flow over a slender cylinder in the presence of a chemical reaction. The buoyancy effect due to thermal diffusion and species diffusion is investigated. Employing suitable similarity transformations, the governing equations are transformed into a system of coupled non-linear ordinary differential equations and are solved numerically via the implicit, iterative, second order finite difference method. The numerical results obtained are compared with the available results in the literature for some special cases and the results are found to be in excellent agreement. The velocity, temperature, and the concentration profiles are presented graphically and analyzed for several sets of the pertinent parameters. The pooled effect of the thermal and mass Grashof number is to enhance the velocity and is quite the opposite for temperature and the concentration fields.
Źródło:
International Journal of Applied Mechanics and Engineering; 2016, 21, 1; 121-141
1734-4492
2353-9003
Pojawia się w:
International Journal of Applied Mechanics and Engineering
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Magnetohydrodynamic effect on axisymmetric Stokes flow past a weakly permeable spheroid with a solid core
Autorzy:
Prasad, M. K.
Bucha, T.
Powiązania:
https://bibliotekanauki.pl/articles/38627950.pdf
Data publikacji:
2021
Wydawca:
Instytut Podstawowych Problemów Techniki PAN
Tematy:
spheroid
MHD effect
modified Stokes law
modified Darcy’s law
BJSJ condition
drag
Opis:
The current research is focused on the creeping motion of fluid past a permeable spheroidal particle that has an impermeable core under the magnetic forces. Motion in the permeable zone is proposed to be regulated by Darcy’s law. At the fluid-porous interface, the continuity of the normal velocity component is assumed together with the balance of pressure with normal stresses and the Beavers–Joseph–Saffman–Jones (BJSJ) slip boundary condition. Vanishing of the normal component of velocity is used at the surface of the impermeable core. The drag on the spheroidal particle is obtained in an analytical form. The reliability of the drag coefficient on significant physical parameters such as permeability, non-sphericity parameter, Hartmann numbers, separation parameter (the measure of closeness between the porous particle and the core), and slip parameters is examined. Comparisons of results are made with the cases having no magnetic effect and show that the applied magnetic field possesses the ability to reduce the rate of flow of fluid. Well-known previously published results are deduced from the current analysis.
Źródło:
Archives of Mechanics; 2021, 73, 5-6; 599-633
0373-2029
Pojawia się w:
Archives of Mechanics
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Comparative performance with different versions of low heat rejection combustion chambers with crude rice bran oil
Porównanie osiągów różnych wersji komór spalania o małych stratach ciepła przy wykorzystaniu surowego oleju roślinnego z otrąb ryżowych
Autorzy:
Murali, K. M. V. S.
Rao, N. D. P.
Prasad, B. A.
Murthy, P. V. K.
Powiązania:
https://bibliotekanauki.pl/articles/140033.pdf
Data publikacji:
2014
Wydawca:
Polska Akademia Nauk. Czytelnia Czasopism PAN
Tematy:
alternate fuels
vegetable oil
biodiesel
LHR engine
fuel performance
exhaust emissions
combustion characteristics
paliwa alternatywne
olej roślinny
silnik o małych stratach ciepła
wydajność paliwa
emisja spalin
charakterystyka spalania
Opis:
It has been found that the vegetable oils are promising substitute, because of their properties are similar to those of diesel fuel and they are renewable and can be easily produced. However, drawbacks associated with crude vegetable oils are high viscosity, low volatility call for low heat rejection combustion chamber, with its significance characteristics of higher operating temperature, maximum heat release, and ability to handle lower calorific value (CV) fuel etc. Experiments were carried out to evaluate the performance of an engine consisting of different low heat rejection (LHR) combustion chambers such as ceramic coated cylinder head-LHR-1, air gap insulated piston with superni (an alloy of nickel) crown and air gap insulated liner with superni insert – LHR-2; and ceramic coated cylinder head, air gap insulated piston and air gap insulated liner – LHR-3 with normal temperature condition of crude rice bran oil (CRBO) with varied injector opening pressure. Performance parameters (brake thermal efficiency, brake specific energy consumption, exhaust gas temperature, coolant load, and volumetric efficiency) and exhaust emissions [smoke levels and oxides of nitrogen [NOx]] were determined at various values of brake mean effective pressure of the engine. Combustion characteristics [peak pressure, time of occurrence of peak pressure, maximum rate of pressure rise] were determined at full load operation of the engine. Conventional engine (CE) showed compatible performance and LHR combustion chambers showed improved performance at recommended injection timing of 27 degrees bTDC and recommend injector opening pressure of 190 bar with CRBO operation, when compared with CE with pure diesel operation. Peak brake thermal efficiency increased relatively by 7%, brake specific energy consumption at full load operation decreased relatively by 3.5%, smoke levels at full load decreased relatively by 11% and NOx levels increased relatively by 58% with LHR-3 combustion chamber with CRBO at an injector opening pressure of 190 bar when compared with pure diesel operation on CE.
Jak wiadomo, oleje roślinne są obiecującym substytutem paliw ropopochodnych, ponieważ ich właściwości są podobne do oleju dieslowskiego, są odnawialne i łatwe do wyprodukowania. Niemniej, surowe oleje roślinne wykazują wady, takie jak wysoka lepkość i mała lotność, co wymaga komory spalania o małych stratach ciepła, której istotnymi cechami są m.in. wyższa temperatura robocza, maksymalne wydzielanie ciepła i zdolność do wykorzystania paliwa o mniejszej wartości kalorycznej (CV). Przeprowadzono eksperymenty mające na celu ocenę osiągów silnika z różnymi komorami spalania o małych stratach ciepła (LHR), takich jak głowica cylindra o pokryciu ceramicznym (LHR-1), tłok izolowany szczeliną powietrzną z denkiem ze stopu Superni (superstop niklu) i tuleją cylindra z wkładką z Superni izolowaną szczeliną powietrzną (LHR-2) oraz głowica cylindra z pokryciem ceramicznym, tłok i tuleja cylindra izolowane szczelinami powietrznymi (LHR-3). Badania prowadzono przy normalnej temperaturze oleju roślinnego (surowy olej z otrąb ryżowych, CRBO) i zmiennym ciśnieniu w otworze wtryskiwacza. Parametry osiagów silnika (użyteczna sprawność termiczna, użyteczny współczynnik zużycia energii, temperatura gazu wydychanego, obciążenie obiegiem chłodziwa i współczynnik napełnienia) oraz emisje wydechowe [poziomy dymu i tlenków azotu, NOx] zostały wyznaczone przy różnych wartościach średniego użytecznego ciśnienia w silniku. Charakterystyki spalania [ciśnienie szczytowe, czas występowania ciśnienia szczytowego, maksymalna szybkość wzrostu ciśnienia] zostały wyznaczone w warunkach pracy silnika z pełnym obciążeniem. W porównaniu z silnikiem napędzanym olejem diesla, silnik konwencjonalny (CE) wykazał podobne osiągi przy pracy z olejem roślinnym (CRBO), a w komorach spalania o małych stratach ciepła (LHR) uzyskano lepsze osiągi przy zalecanym kącie wtrysku 27b stopni TDC (przed górnym punktem zwrotnym) i zalecanym ciśnieniu w otworze wtryskiwacza równym 190 bar. Szczytowa użyteczna sprawność cieplna wzrosła relatywnie o 7%, użyteczny współczynnik zużycia energii zmalał o 3,5% przy pracy z pełnym obciążeniem, poziomy dymu przy pełnym obciążeniu zmalały o 11%, a poziom tlenków NOx wzrósł relatywnie o 58% w przypadku komory spalania typu LHR-3 napędzanej olejem roślinnym CBRO przy ciśnieniu w otworze wtryskiwacza 190 bar, w porównaniu z parametrami uzyskanymi przy pracy z czystym olejem diesla.
Źródło:
Archive of Mechanical Engineering; 2014, LXI, 4; 627-651
0004-0738
Pojawia się w:
Archive of Mechanical Engineering
Dostawca treści:
Biblioteka Nauki
Artykuł
    Wyświetlanie 1-19 z 19

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