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Wyszukujesz frazę "Kumar, S. R." wg kryterium: Autor


Wyświetlanie 1-56 z 56
Tytuł:
Transient finite element simulation and microstructure evolution of AA2219 weld joint using gas tungsten arc welding process
Autorzy:
Arunkumar, S.
Shrikrishna, A. K.
Paulraj, S.
Devakumaran, K.
Kumar, S. R.
Powiązania:
https://bibliotekanauki.pl/articles/101882.pdf
Data publikacji:
2016
Wydawca:
Stowarzyszenie Inżynierów i Techników Mechaników Polskich
Tematy:
AA2219 aluminium alloy
gas tungsten arc welding
finite element simulation
metallurgical characterization
Opis:
In this study we focus on finite element simulation of gas tungsten arc welding (GTAW) of AA2219 aluminum alloy and the behavioral of the microstructure before and after weld. The simulations were performed using commercial COMSOL Multiphysics software. The thermal history of the weld region was studied by initially developed mathematical model. A sweep type meshing was used and transient analysis was performed for one welding cycle. The highest temperature noted was 3568 °C during welding. The welding operation was performed on 200×100×25 mm plates. Through metallurgical characterization, it was observed that a fair copper rich cellular (CRC) network existed in the weld region. A small amount of intermetallic compounds like Al2Cu is observed through the XRD pattern.
Źródło:
Advances in Science and Technology. Research Journal; 2016, 10, 31; 64-73
2299-8624
Pojawia się w:
Advances in Science and Technology. Research Journal
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
A Comparison of Muscular Activity Involved in the Use of Two Different Types of Computer Mouse
Autorzy:
Kumar, R.
Kumar, S.
Powiązania:
https://bibliotekanauki.pl/articles/90400.pdf
Data publikacji:
2008
Wydawca:
Centralny Instytut Ochrony Pracy
Tematy:
muscular activity
EMG
computer mouse
Opis:
Two types of computer input devices, a conventional mouse and a roller bar one, were studied in terms of muscular activitiy in m. trapezius dexter, m. deltoideus anterior dexter and m. extensor digitorum dexter, and comfort rating. Fifteen university students and employees participated in this study. The order of the devices was random. While a task was performed, electromyography (EMG) data were recorded for each test. Muscular activity was found to be significantly lower for the roller bar mouse than for the conventional one. Comfort rating indicated there was a significant difference in moving a cursor with the conventional mouse compared to the roller bar one. It is concluded that a roller bar mouse allowed the subjects to work closer to the body compared to the conventional one, thus the former can be recommended as a general means of reducing upper extremity musculoskeletal disorders.
Źródło:
International Journal of Occupational Safety and Ergonomics; 2008, 14, 3; 305-311
1080-3548
Pojawia się w:
International Journal of Occupational Safety and Ergonomics
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Reflection and transmission of plane waves between two different fluid saturated porous half spaces
Autorzy:
Kumar, R.
Miglani, A.
Kumar, S.
Powiązania:
https://bibliotekanauki.pl/articles/202265.pdf
Data publikacji:
2011
Wydawca:
Polska Akademia Nauk. Czytelnia Czasopism PAN
Tematy:
porous
amplitude ratios
reflection
transmission
longitudinal waves
Opis:
The present study is concerned with the reflection and transmission of plane waves between two different fluid saturated porous half spaces when longitudinal and transversal waves impinge obliquely at the interface. Amplitude ratios of various reflected and transmitted waves are obtained .The variations of amplitude ratios with angle of incidence are depicted graphically. A particular case of reflection at the free surface in fluid saturated porous half spaces has been deduced and discussed. A special case of interest has also been deduced from the present investigation.
Źródło:
Bulletin of the Polish Academy of Sciences. Technical Sciences; 2011, 59, 2; 227-234
0239-7528
Pojawia się w:
Bulletin of the Polish Academy of Sciences. Technical Sciences
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Eigenvalue approach to nanobeam in modified couple stress thermoelastic with three-phase-lag model induced by ramp type heating
Autorzy:
Kumar, R.
Devi, S.
Powiązania:
https://bibliotekanauki.pl/articles/279203.pdf
Data publikacji:
2017
Wydawca:
Polskie Towarzystwo Mechaniki Teoretycznej i Stosowanej
Tematy:
modified couple stress thermoelastic
eigenvalue approach
nanobeam
Opis:
This article deals with the study of a thermoelastic nanobeam in a modified couple stress theory subjected to ramp-type heating. The mathematical model is prepared for the nanobeam in thermoelastic three-phase-lag. The Laplace transform and the eigenvalue approach are used to find the displacement component, lateral deflection, temperature change and axial stress of the thermoelastic beam. The general algorithm of the inverse Laplace transform is developed to compute results numerically. The comparison of three-phase-lag, dual-phaselag and GN-III (1993) models are represented, and their illustration is depicted graphically. This study finds the applications in engineering, medical science, sensors, etc.
Źródło:
Journal of Theoretical and Applied Mechanics; 2017, 55, 3; 1067-1079
1429-2955
Pojawia się w:
Journal of Theoretical and Applied Mechanics
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Microstructural considerations on SH-wave propagation in a piezoelectric layered structure
Autorzy:
Goyal, R.
Kumar, S.
Powiązania:
https://bibliotekanauki.pl/articles/280348.pdf
Data publikacji:
2018
Wydawca:
Polskie Towarzystwo Mechaniki Teoretycznej i Stosowanej
Tematy:
SH-wave
piezoelectricity
couple stress
characteristic length
Opis:
Shear wave based acoustic devices are being used in gaseous and liquid environments because of their high-sensitivity. The theoretical study of horizontally polarized shear (SH) waves in a layered structure consisting of a piezoelectric ceramic of P ZT − 5H or BaT iO3 material overlying a couple stress substrate is presented in this paper. The considered substrate is supposed to be exhibiting microstructural properties. The closed form expression of dispersion relations are derived analytically for electrically open and short conditions. The effects of internal microstructures of the couple stress substrate, thickness of P ZT − 5H or BaT iO3 ceramic, piezoelectric and dielectric constants are illustrated graphically on the phase velocity of the piezoelectric layer under electrically open and short conditions.
Źródło:
Journal of Theoretical and Applied Mechanics; 2018, 56, 4; 993-1004
1429-2955
Pojawia się w:
Journal of Theoretical and Applied Mechanics
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Flow behavior in weakly permeable micro-tube with varying viscosity near the wall
Autorzy:
Gupta, R. R.
Kumar, V.
Chand, S.
Powiązania:
https://bibliotekanauki.pl/articles/779656.pdf
Data publikacji:
2017
Wydawca:
Zachodniopomorski Uniwersytet Technologiczny w Szczecinie. Wydawnictwo Uczelniane ZUT w Szczecinie
Tematy:
hollow-fiber
micro-tube
permeation
algorithm
variable viscosity
velocity profile
equation of motion
navier-stokes equation
Opis:
Weakly permeable micro-tubes are employed in many applications involving heat and/or mass transfer. During these processes, either solute concentration builds up (mass transfer) or steep change in temperature (heat transfer) takes place near the permeable wall causing a change in the viscosity of the fluid. Results of the present work suggest that such change in viscosity leads to a considerable alteration in the flow behavior, and the commonly assumed parabolic velocity profile no longer exists. To solve the problem numerically, the equation of motion was simplified to represent permeation of incompressible, Newtonian fluid with changing viscosity through a micro-tube. Even after considerable simplification, the accuracy of the results was the same as that obtained by previously reported results for some specific cases using rigorous formulation. The algorithm developed in the present work is found to be numerically robust and simple so that it can be easily integrated with other simulations.
Źródło:
Polish Journal of Chemical Technology; 2017, 19, 4; 16-21
1509-8117
1899-4741
Pojawia się w:
Polish Journal of Chemical Technology
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Inventory models with multiple production and remanufacturing batches under shortages
Autorzy:
Singh, S. R.
Sharma, S.
Kumar, M.
Powiązania:
https://bibliotekanauki.pl/articles/206729.pdf
Data publikacji:
2016
Wydawca:
Polska Akademia Nauk. Instytut Badań Systemowych PAN
Tematy:
inventory models
production
remanufacturing
shortages
Opis:
Owing to the ecological requirements and regulations, an enormous concern is being paid to the product re-processing. In the established literature, researchers considered that the remanufactured items are as good as the new ones. Yet, such an assumption is not convenient, as in many real situations the recycled products are considered by the customers to be of secondary quality. Further, the classical studies mainly addressed the inventory models without shortages, and this is not applicable in many practical business situations. This paper extends the reverse logistics inventory models with finite production and remanufacturing rate along with the assumption that newly produced and repaired (remanufactured) objects are not of same characteristics. Shortages are allowed and numerous stock-out cases are discussed. The collected used items are remanufactured (repaired) and non-repaired products are disposed off. The proposed models are illustrated with some numerical examples and their results are discussed.
Źródło:
Control and Cybernetics; 2016, 45, 3; 385-416
0324-8569
Pojawia się w:
Control and Cybernetics
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Seasonal changes of sedimentation rates and sediment characteristics status in the Gulf of Mannar Coral Island, India
Autorzy:
Yogesh Kumar, J.S.
Geetha, S.
Sornaraj, R.
Powiązania:
https://bibliotekanauki.pl/articles/11860.pdf
Data publikacji:
2014
Wydawca:
Przedsiębiorstwo Wydawnictw Naukowych Darwin / Scientific Publishing House DARWIN
Tematy:
seasonal change
sedimentation rate
sediment status
Mannar Gulf
Coral Island
coral reef
marine sediment
Thoothukudi group
Vembar group
India
Opis:
Corals are known to flourish in various turbid environments around the world. The quantitative distinction between clear and turbid water in coral habitats is not well defined nor are the amount of sediment in suspension and rates of sedimentation used to evaluate the condition of reef environments well established. This study of sedimentation rate, sediment composition and pH, OC deposition was on a fringing reef flat off Thoothukudi and Vembar group of islands, Gulf of Mannar, India. In the present study the sedimentation rate ranged from 1.97 mg/cm2/day to 12.31 mg/cm2/day. The percentage of sand in the sediment was higher than silt and clay. The organic carbon level in all the study stations ranged from 0.03 to 2.54. The sediment pH of the six studied stations was highly acidic in nature at all the study sites in the Gulf of Mannar.
Źródło:
International Letters of Natural Sciences; 2014, 01
2300-9675
Pojawia się w:
International Letters of Natural Sciences
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Synthesis and Characterization of Functionally Graded Al-6Cr-Y2O3 Composites
Autorzy:
Satish Kumar, T.
Krishna Kumar, K.
Shalini, S.
Subramanian, R.
Powiązania:
https://bibliotekanauki.pl/articles/353460.pdf
Data publikacji:
2018
Wydawca:
Polska Akademia Nauk. Czytelnia Czasopism PAN
Tematy:
Al-6Cr alloy
powder metallurgy
functionally graded materials
wear resistance
Opis:
The present investigation aims at fabricating a functionally graded Al-6Cr-Y2O3 composite and its microstructural and property characterization. Al-6Cr-alloys with varying percentage of Y2O3 (5-10 vol. %) have been used to fabricate FGM by powder metallurgy route. The samples were subsequently subjected to solution treatment at 610°C for 4h followed by artificially aged at 310°C for 4h. The microstructure, hardness and wear behavior of these FGM have been evaluated. FGM exhibited superior hardness (360 ± 5 VHN) as compared to the unprocessed composites (220 ± 5 VHN) due to the uniform dispersion of Y2O3 particles. Wear resistance of Al-6Cr-10Y2O3 FGM were compared that of with pure Al-6Cr alloy by dry abrasive wear test. Al-6Cr-10Y2O3 FGM composites were found to exhibit higher wear resistance with the minimum wear rate of 0.009 mm3/m compared to the Al-6Cr alloy wear rate 0.02 mm3/m.
Źródło:
Archives of Metallurgy and Materials; 2018, 63, 4; 1649-1655
1733-3490
Pojawia się w:
Archives of Metallurgy and Materials
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Probabilistic analysis of two reliability models of a single-unit system with preventive maintenance beyond warranty and degradation
Analiza probabilistyczna dwóch modeli niezawodności systemu jednoelementowego wykorzystujących pojęcia pogwarancyjnej obsługi profilaktycznej oraz degradacji
Autorzy:
Niwas, R.
Kadyan, M. S.
Kumar, J.
Powiązania:
https://bibliotekanauki.pl/articles/301952.pdf
Data publikacji:
2015
Wydawca:
Polska Akademia Nauk. Polskie Naukowo-Techniczne Towarzystwo Eksploatacyjne PAN
Tematy:
probabilistic analysis
reliability
preventive maintenance
warranty
degradation
analiza probabilistyczna
niezawodność
obsługa profilaktyczna
gwarancja
degradacja
Opis:
This paper presents two reliability models of a single-unit system with the concept of preventive maintenance (PM) beyond warranty and degradation. In both the models, repair of any failure during warranty is cost-free to the users, provided failures are not due to the negligence of users. There is a single repairman who always remains with the system. Beyond warranty, the unit goes under PM and works as new after PM (in both models). In model-1, the unit works as new after its repair beyond warranty whereas; in model-2, the unit becomes degraded. After failure, the degraded unit is replaced by a new one. The failure time of the system follows negative exponential distribution while PM, replacement and repair time distributions are taken as arbitrary with different probability density functions. Supplementary variable technique is adopted to derive the expressions for some economic measures such as reliability, mean time to system failure (MTSF), availability and profit function. Using Abel’s lemma, the behaviour of the system in steady-state has been examined. To highlight the behaviour of reliability and profit function, numerical results are considered for particular values of various parameters and repair cost. Profit comparison of both the models is also made to see the usefulness of the concept of degradation.
W artykule przedstawiono dwa modele niezawodności systemu jednoelementowego wykorzystujące pojęcia pogwarancyjnej obsługi profilaktycznej oraz degradacji. Oba modele zakładają, że w okresie gwarancyjnym użytkownik nie ponosi żadnych kosztów związanych z naprawą uszkodzeń, chyba że uszkodzenie powstało wskutek zaniedbania ze strony użytkownika. Obsługi są wykonywane przez jedną ekipę remontową, która zawsze pozostaje na stanowisku. Po upływie okresu gwarancyjnego, urządzenie podlega obsłudze profilaktycznej i po jej przeprowadzeniu działa jak nowe (w obu modelach). Model 1 zakłada, że element po naprawie pogwarancyjnej działa jak nowy, natomiast w Modelu 2, element ulega degradacji. Zdegradowany element, który uległ uszkodzeniu, zostaje wymieniony na nowy. Rozkład czasu uszkodzenia jest rozkładem wykładniczym ujemnym, a rozkłady czasu obsługi profilaktycznej, wymiany i naprawy są traktowane jako arbitralne, o różnych funkcjach gęstości prawdopodobieństwa. Zastosowana technika dodatkowej zmiennej pozwoliła na wyprowadzenie wyrażeń dla niektórych miar ekonomicznych, takich jak niezawodność, średni czas do uszkodzenia systemu (MTSF), gotowość i funkcja zysków. Zachowanie systemu w stanie ustalonym badano z wykorzystaniem lematu Abela. Aby przedstawić zachowanie funkcji niezawodności i zysków, analizowano wyniki numeryczne dla poszczególnych wartości różnych parametrów oraz kosztów naprawy. Porównanie zyskowności badanych modeli umożliwiło weryfikację przydatności pojęcia degradacji.
Źródło:
Eksploatacja i Niezawodność; 2015, 17, 4; 535-543
1507-2711
Pojawia się w:
Eksploatacja i Niezawodność
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Phase-lag effects in skin tissue during transient heating
Autorzy:
Kumar, R.
Vashishth, A. K.
Ghangas, S.
Powiązania:
https://bibliotekanauki.pl/articles/264536.pdf
Data publikacji:
2019
Wydawca:
Uniwersytet Zielonogórski. Oficyna Wydawnicza
Tematy:
tkanka skórna
transformata Laplace'a
opóźnienie trójfazowe
bioheat transfer
skin tissue
three-phase-lag
Laplace transform
transient heating
Opis:
A three-phase-lag (TPL) model is proposed to describe heat transfer in a finite domain skin tissue with temperature dependent metabolic heat generation. The Laplace transform method is applied to solve the problem. Three special types of heat flux are applied to the boundary of skin tissue for thermal therapeutic applications. The depth of tissue is influenced by the different oscillation heat flux. The comparison between the TPL and dual-phase-lag (DPL) models is analyzed and the effects of phase lag parameters […] and material constant […] on the tissue temperature distribution are presented graphically.
Źródło:
International Journal of Applied Mechanics and Engineering; 2019, 24, 3; 603-623
1734-4492
2353-9003
Pojawia się w:
International Journal of Applied Mechanics and Engineering
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Variable gravity effects on thermal instability of nanofluid in anisotropic porous medium
Autorzy:
Chand, R.
Rana, G. C.
Kumar, S.
Powiązania:
https://bibliotekanauki.pl/articles/265426.pdf
Data publikacji:
2013
Wydawca:
Uniwersytet Zielonogórski. Oficyna Wydawnicza
Tematy:
porowatość
liczba Rayleigha
zmienna grawitacja
nanofluid
anisotropic porous medium
Rayleigh number
variable gravity
Opis:
In this paper, we study the effects of variable gravity on thermal instability in a horizontal layer of a nanofluid in an anisotropic porous medium. Darcy model been used for the porous medium. Also, it incorporates the effect of Brownian motion along with thermophoresis. The normal mode technique is used to find the confinement between two free boundaries. The expression of the Rayleigh number has been derived, and the effects of variable gravity and anisotropic parameters on the Rayleigh number have been presented graphically.
Źródło:
International Journal of Applied Mechanics and Engineering; 2013, 18, 3; 631-642
1734-4492
2353-9003
Pojawia się w:
International Journal of Applied Mechanics and Engineering
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Unsteady three-dimensional MHD nanofluid flow over a stretching sheet with variable wall thickness and slip effects
Autorzy:
Kumar, G. Vinod
Varma, S. V. K.
Kumar, R. V. M. S. S. K.
Powiązania:
https://bibliotekanauki.pl/articles/265665.pdf
Data publikacji:
2019
Wydawca:
Uniwersytet Zielonogórski. Oficyna Wydawnicza
Tematy:
pole magnetyczne
magnetohydrodynamika
poślizg
unsteady flow
magnetic field
Buongiorno’s model
variable wall thickness sheet
velocity
thermal and solutal slip
Opis:
The stretching sheets with variable thickness may occur in engineering applications more frequently than a flat sheet. Due to its various applications, in the present analysis we considered a three dimensional unsteady MHD nanofluid flow over a stretching sheet with a variable wall thickness in a porous medium. The effects of radiation, viscous dissipation and slip boundary conditions are considered. Buongiorno’s model is incorporated to study the combined effects of thermophoresis and Brownian motion. The dimensionless governing equations are solved by using MATLAB bvp4c package. The impact of various important flow parameters is presented and analysed through graphs and tables. It is interesting to note that all the three boundary layer thicknesses are diminished by slip parameters. Further, the unsteady parameter decreases the hydromagnetic boundary layer thickness.
Źródło:
International Journal of Applied Mechanics and Engineering; 2019, 24, 3; 709-724
1734-4492
2353-9003
Pojawia się w:
International Journal of Applied Mechanics and Engineering
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Screening and characterization of Fibrinolytic protease producing Bacillus circulans from mangrove sediments pitchavaram, South East Coast of India
Autorzy:
Sadeesh Kumar, R.
Rajesh, R.
Gokulakrishnan, S.
Subramanian, J.
Powiązania:
https://bibliotekanauki.pl/articles/11234.pdf
Data publikacji:
2015
Wydawca:
Przedsiębiorstwo Wydawnictw Naukowych Darwin / Scientific Publishing House DARWIN
Opis:
Regulation and production of Fibrinolytic enzymes from bacterial sources especially from Bacillus strains has taken a leading role in the medical sciences for the treatment of cardiovascular disorders as it removes thrombus or clots adding to its significant role in curing human health issues saving millions. Significant progress has been made during the last few years on the studies of fibrinolytic enzymes in identifying, cloning, purification, characterization and overproduction of these for commercialization in medical sciences and in fields like detergents development. Production of fibrinolytic enzyme from Bacillus circulans was done using Nutrient broth medium. In addition, a strong fibrinolytic enzyme was purified from the cultivation media. The purified enzyme was almost homogeneous with other species of same genus, as examined by SDS−PAGE and sephadex G-75 column chromatography. The enzyme had an optimal pH of 7-12, an optimal temperature of 50 °C, for fibrin hydrolysis. The molecular mass estimated by gel filtration was 24 to36 KDa. Further studies for characterization and structural elucidation are necessary for their medicinal applications and molecular biological characteristics.
Źródło:
International Letters of Natural Sciences; 2015, 01
2300-9675
Pojawia się w:
International Letters of Natural Sciences
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Low-Power High-Speed Double Gate 1-bit Full Adder Cell
Autorzy:
Kumar, R.
Roy, S.
Bhunia, C. T.
Powiązania:
https://bibliotekanauki.pl/articles/226653.pdf
Data publikacji:
2016
Wydawca:
Polska Akademia Nauk. Czytelnia Czasopism PAN
Tematy:
low-power full-adder
low-power CMOS design
multiplexer based full-adder design
multi-threshold voltage based full-adder design
pass transmission logic
Opis:
In this paper, we proposed an efficient full adder circuit using 16 transistors. The proposed high-speed adder circuit is able to operate at very low voltage and maintain the proper output voltage swing and also balance the power consumption and speed. Proposed design is based on CMOS mixed threshold voltage logic (MTVL) and implemented in 180nm CMOS technology. In the proposed technique the most time-consuming and power consuming XOR gates and multiplexer are designed using MTVL scheme. The maximum average power consumed by the proposed circuit is 6.94μW at 1.8V supply voltage and frequency of 500 MHz, which is less than other conventional methods. Power, delay, and area are optimized by using pass transistor logic and verified using the SPICE simulation tool at desired broad frequency range. It is also observed that the proposed design may be successfully utilized in many cases, especially whenever the lowest power consumption and delay are aimed.
Źródło:
International Journal of Electronics and Telecommunications; 2016, 62, 4; 329-334
2300-1933
Pojawia się w:
International Journal of Electronics and Telecommunications
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Wear characteristics and defects analysis of friction stir welded joint of aluminium alloy 6061-T6
Charakterystyka zużycia i analiza uszkodzeń złącza ze stopu aluminium 6061-T6 zgrzewanego tarciowo z przemieszaniem
Autorzy:
Kumar, R.
Chattopadhyaya, S.
Hloch, S.
Krolczyk, G.
Legutko, S.
Powiązania:
https://bibliotekanauki.pl/articles/1365830.pdf
Data publikacji:
2016
Wydawca:
Polska Akademia Nauk. Polskie Naukowo-Techniczne Towarzystwo Eksploatacyjne PAN
Tematy:
friction stir welding (FSW)
wear
defect
grinding machine
field emission scanning electron microscope (FESEM)
zgrzewanie tarciowe z przemieszaniem
zużycie
uszkodzenie
szlifierka
mikroskopy polowe
Opis:
This paper deals with the wear characteristics and defects developed during friction stir welding at different process parameter of aluminium alloy (AA) 6061-T6 having thickness 6 mm. Four welded samples are prepared with rotational speed 500 rpm, 710 rpm, 1000 rpm and with welding speed of 25 mm/min & 40 mm/min. Welded samples and base material are put in wear condition under grinding machine for 120 s. Material removal is measure by taking the difference of weight before and after wear. Different types of defects and fracture are observed on the wear surface. These defects and fractures are analysed under field emission scanning electron microscope (FESEM). It is concluded that material removal from welded sample is less compared to base metal, hence wear resistance increases after friction stir welding.
Praca dotyczy charakterystyki zużycia i uszkodzeń podczas zgrzewania tarciowego z przemieszaniem stopu aluminium (AA) 6061T6 o grubości 6 mm dla zmiennych parametrów. Cztery zgrzewane próbki były wykonane z prędkością obrotową 500 obr/min, 710 obr/min, 1000 obr/min dla prędkości zgrzewania 25 mm/min i 40 mm/min. Zgrzewane próbki i materiał bazowy były poddawane zużywaniu za pomocą szlifierki w czasie 120 s. Ubytek materiału mierzono jako różnicę wagi przed i po zużywaniu. Różne rodzaje wad i pęknięć zaobserwowano na zużytej powierzchni. Wady i pęknięcia analizowano za pomocą mikroskopu polowego (FESEM). Stwierdzono, że ubytek materiału ze zgrzewanych próbek jest mniejszy w porównaniu z ubytkiem dotyczącym materiału bazowego. Zwiększa się więc odporność na zużycie po zgrzewaniu tarciowym z przemieszaniem.
Źródło:
Eksploatacja i Niezawodność; 2016, 18, 1; 128-135
1507-2711
Pojawia się w:
Eksploatacja i Niezawodność
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Design and development of 3-stage determination of damage location using Mamdani-Adaptive Genetic-Sugeno model
Autorzy:
Sahu, S.
Kumar, P. B.
Parhi, D. R.
Powiązania:
https://bibliotekanauki.pl/articles/281979.pdf
Data publikacji:
2017
Wydawca:
Polskie Towarzystwo Mechaniki Teoretycznej i Stosowanej
Tematy:
damage
Mamdani FIS
Sugeno FIS
Adaptive Genetic Algorithm
vibration
natural frequencies
Opis:
Damage detection in structural elements like beams is one of important research areas for health monitoring. Initiation of a fault in the form of a crack or any damage puts a limitation on the service life of a structural member. So, in this paper, a method is proposed which uses the advantages of soft computing techniques like Fuzzy Inference Systems (Mamdani and Sugeno) and Adaptive Genetic Algorithm for three stage refinement of the data base generated using dynamic responses from a cracked fixed-free aluminum alloy beam element. For the crack element reference, a finite element model of a single transverse crack has been considered. The proposed method describes both Mamdani and Sugeno Fuzzy Inference Systems for training of damage parameters. In the Adaptive Genetic Algorithm, a statistics based method has been incorporated to limit the randomness of the search process. Finally, the results from the Mamdani-Adaptive Genetic-Sugeno model (MAS) are validated with the results from the experimental analysis.
Źródło:
Journal of Theoretical and Applied Mechanics; 2017, 55, 4; 1325-1339
1429-2955
Pojawia się w:
Journal of Theoretical and Applied Mechanics
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Parametric studies and simulation of PSA process for oxygen production from air
Autorzy:
Beeyani, A.
Singh, K.
Vyas, R.
Kumar, S.
Powiązania:
https://bibliotekanauki.pl/articles/779567.pdf
Data publikacji:
2010
Wydawca:
Zachodniopomorski Uniwersytet Technologiczny w Szczecinie. Wydawnictwo Uczelniane ZUT w Szczecinie
Tematy:
amplituda ciśnienia adsorpcji
model matematyczny
symulacja
produkcji tlenu
MATLAB
Zeolit5A
pressure swing adsorption
mathematical model
simulation
oxygen production
Zeolite 5A
Opis:
A numerical simulation and parametric studies for the separation of air using 5A zeolite for the production of oxygen are presented for a basic two bed pressure swing adsorption (PSA) process. The simulation is based on an in-house program 'PSASOL' developed in MATLABŽ. The transient process of PSA has been described by a set of partial differential equations, which were solved using a finite difference method. Simulation results have been validated with the experimental data from literature. Based on the simulation results, an optimal set of operational parameter values has been obtained for the PSA bed. The values of the optimal parameters, viz. adsorption pressure, cycle time, feed rate, and product rate have been found to be 2.5 atm, 150 s, 15 cm3/s, and 2.55 cm3/s, respectively. For the optimal conditions, purity of 95.45% and recovery of 77.3% have been achieved. It has also been found that a longer tubular unit with the length to diameter (L/D) ratio of 10.5 is advantageous. The estimated pressure drop across the bed has been found to be negligible. Power consumption and productivity have also been computed.
Źródło:
Polish Journal of Chemical Technology; 2010, 12, 2; 18-28
1509-8117
1899-4741
Pojawia się w:
Polish Journal of Chemical Technology
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Evidence of amorphous Ca-phosphate precipitate caused by bio mineralisation in 4-5th CE lime plasters of the previously submerged east coastal monument of Salvankuppam
Autorzy:
Singh, Manager R.
Kumar, S. Vinodh
Ganaraj, Kuntikana
Powiązania:
https://bibliotekanauki.pl/articles/2086560.pdf
Data publikacji:
2021
Wydawca:
Polskie Towarzystwo Mineralogiczne
Tematy:
Amorphous Ca-phosphate
16S rRNA
Bio-mineralization
calcite
lime plasters
Opis:
The lime plasters of the excavated monument of Salvankuppam, previously submerged and exposed by the Tsunami occurred in the Indian Ocean on 26th December 2004 was studied with different analytical techniques. The temple is dated 4-5th century CE. The XRF, XRD, FTIR, NMR, SEM-EDX analysis of the lime plasters evidenced particular occurrence of phosphatised bacterial remains in saline conditions. The formation of amorphous Ca-phosphate by bio mineralization was identified in the plasters by the analyses. The plasters are made of air-lime with coarse aggregates and seashells inclusion as confirmed by the thermal and chemical analysis. The microstructure and morphological investigations of mineralized microbial structures by SEM-EDX indicated the formation of amorphous Ca-phosphate. The unordered and fibrous spherulites have hardened and reduced porosity of the plaster by bio mineralization as observed through MIP analysis. The 16S rRNA sequencing has identified the Pseudomonas strains mainly responsible for the clustering of amorphous Ca-phosphate particles around the bacterial colony.
Źródło:
Mineralogia; 2021, 52, 1; 19--30
1899-8291
1899-8526
Pojawia się w:
Mineralogia
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Meiotic studies in some members of Caryophyllaceae Juss. from the Western Himalayas
Autorzy:
Jeelani, S.M.
Rani, S.
Kumar, S.
Kumari, S.
Gupta, R.C.
Powiązania:
https://bibliotekanauki.pl/articles/19318.pdf
Data publikacji:
2011
Wydawca:
Polska Akademia Nauk. Czytelnia Czasopism PAN
Tematy:
Caryophyllaceae
Himalayas
meiotic process
chromosome number
meiosis
Western Himalayas
pollen grain size
Arenaria kashmirica
Silene conoidea
Silene edgeworthii
Silene moorcroftiana
Silene nepalensis
Stellaria media
Stellaria monosperma
Stellaria semivestita
Lychnis coronaria
Silene vulgaris
India
Gypsophilla ceratioides
Opis:
The paper reports meiotic studies on 50 populations comprising 12 species belonging to 5 genera of Caryophyllaceae from the Western Himalayas. The chromosome numbers in Arenaria kashmirica (n=20), Silene conoidea (n=20), S. edgeworthii (n=12 and n=24), S. moorcroftiana (n=24), S. nepalensis (n=12), Stellaria media (n=13), S. monosperma (n=13) and S. semivestita (n=13) are reported for the first time. The chromosome numbers in Lychnis coronaria (n=12) and Silene vulgaris (n=24) are given for the first time from India, along with Gypsophilla ceratioides (n=15) from the Western Himalayas. The course of meiosis varies from normal to abnormal in different populations of Silene conoidea, S. edgeworthii, S. vulgaris, Stellaria media, S. monosperma and S. semivestita. The course of meiosis was abnormal in all studied populations of Lychnis coronaria. Abnormal microsporogenesis (cytomixis, chromosomal stickiness, unoriented bivalents, formation of laggards and bridges) led to reduced pollen fertility and differences in pollen grain size.
Źródło:
Acta Biologica Cracoviensia. Series Botanica; 2011, 53, 1
0001-5296
Pojawia się w:
Acta Biologica Cracoviensia. Series Botanica
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Numerical analysis of structure, stability and entropy generation in biogas coflow diffusion flames
Autorzy:
Kumar, R. Nivethana
Kumaran, S. Muthu
Raghavan, Vasudevan
Powiązania:
https://bibliotekanauki.pl/articles/2065757.pdf
Data publikacji:
2022
Wydawca:
Polska Akademia Nauk. Czytelnia Czasopism PAN
Tematy:
biogas
flame stability
entropy generation
coflow air
hydrogen injection
preheated reactant
biogaz
stabilność płomienia
generowanie entropii
wtrysk wodoru
Opis:
Biogas is a gaseous biofuel predominantly composed of methane and carbon-dioxide. Stability of biogas flames strongly depend upon the amount of carbon-dioxide present in biogas, which varies with the source of biomass and reactor. In this paper, a comprehensive study on the stability and flame characteristics of coflow biogas diffusion flames is reported. Numerical simulations are carried out using reactive flow module in OpenFOAM, incorporated with variable thermophysical properties, Fick’s and Soret diffusion, and short chemical kinetics mechanism. Effects of carbon-dioxide content in the biogas, temperatures of the fuel or coflowing air streams (preheated reactant) and hydrogen addition to fuel or air streams are analyzed. Entropy generation in these flames is also predicted. Results show that the flame temperature increases with the degree of preheat of reactants and the flames show better stability with the preheated air stream. Preheating the air contributes to increased flame stability and also to a significant decrease in entropy generation. Hydrogen addition, contributing to the same power rating, is seen to be relatively more effective in increasing the flame stability when added to the fuel stream. Results in terms of flow, temperature, species and entropy fields, are used to describe the stability and flame characteristics.
Źródło:
Archive of Mechanical Engineering; 2022, LXIX, 1; 99--128
0004-0738
Pojawia się w:
Archive of Mechanical Engineering
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Intelligent hybrid fuzzy logic system for damage detection of beam-like structural elements
Autorzy:
Sahu, S.
Kumar, P. B.
Parhi, D. R.
Powiązania:
https://bibliotekanauki.pl/articles/281457.pdf
Data publikacji:
2017
Wydawca:
Polskie Towarzystwo Mechaniki Teoretycznej i Stosowanej
Tematy:
fuzzy logic
differential evolution algorithm
crack
natural frequency
Opis:
Fuzzy logic has been used in different research fields for more than three decades. It has become a robust method to solve complex and intricate problems which are otherwise difficult to solve by traditional methods. But it still requires some human experience and knowledge. In the present study, an attempt is made to design a hybrid optimization technique for automatic formation of the fuzzy knowledge based rules using an evolutionary algorithm. This hybridization technique has been applied in the field of damage detection and location of cracks in cracked structural elements. In this paper, a robust fault diagnostic tool based on a differential evolution algorithm and fuzzy logic has been proposed. Theoretical and Finite Element analyzes are done to model the crack and to find the effect of the presence of cracks on changes of vibrational characteristic (natural frequencies) of a fixed-fixed beam. The inputs to DEA-FL system are the first three relative natural frequencies, and the outputs from the system are the relative crack depth and relative crack location. For the validation of the results obtained from the proposed method and to check the robustness of the controller, experimental analysis is performed. To find average error rates, the bootstrap method has been adopted.
Źródło:
Journal of Theoretical and Applied Mechanics; 2017, 55, 2; 509-521
1429-2955
Pojawia się w:
Journal of Theoretical and Applied Mechanics
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Fundamental solution in micropolar viscothermoelastic solids with void
Autorzy:
Kumar, R.
Sharma, K. D.
Garg, S. K.
Powiązania:
https://bibliotekanauki.pl/articles/265845.pdf
Data publikacji:
2015
Wydawca:
Uniwersytet Zielonogórski. Oficyna Wydawnicza
Tematy:
micropolar thermodiffusion
steady oscillations
visothemoelastic
micropolar with void
drgania
termosprężystość
funkcje elementarne
Opis:
In the present article, we construct the fundamental solution to a system of differential equations in micropolar viscothermoelastic solids with voids in case of steady oscillations in terms of elementary functions. Some basic properties of the fundamental solution are also established.
Źródło:
International Journal of Applied Mechanics and Engineering; 2015, 20, 1; 109-125
1734-4492
2353-9003
Pojawia się w:
International Journal of Applied Mechanics and Engineering
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
A novel revolutionary substantial transformative control technique for solar fed-full bridge converter based energy stabilization for grid connected applications
Autorzy:
Umamaheswari, S.
Karthigaivel, R.
Satheesh Kumar, G.
Vengadachalam, N.
Powiązania:
https://bibliotekanauki.pl/articles/2173656.pdf
Data publikacji:
2022
Wydawca:
Polska Akademia Nauk. Czytelnia Czasopism PAN
Tematy:
high boost full-bridge converter
battery energy storage system
BESS
revolutionary substantial transformative control technique
RSTC
konwerter pełnomostkowy o wysokim wzmocnieniu
akumulatorowy system magazynowania energii
rewolucyjna technika znaczącej kontroli transformacyjnej
Opis:
Nowadays, there is a need to increase the continuous usage of the power electronic converters like AC-DC, DC–DC, and DC–AC based on various applications like mobile charge controller and telecom base station. Also, for power stability control, these converters are utilized in the renewable energy system (RES). The output cannot be stable for a longer duration due to the inappropriate switching pulse and continued usage of the converter. For resolving the above issues, the soft-switching technique is implemented in the proposed system for controlling both converter and inverter for proper energy stabilization during the continuous operation of devices. The main objective of this work is to improve the solar power system using high voltage gain DC / DC converter. Similarly, an inverter delivers the continuous AC power to the grid system without any fluctuations. The revolutionary substantial transformative control (RSTC) technique has been employed to monitor and control the converters used in this system. The additional advantage of this system is battery-based energy management, which is only utilized under necessary conditions. During the initial stage, RSTC will track the solar power, and it compares with the reference voltage and produces the appropriate pulse to the converter switch. Based on the switching pulse, the full-bridge converter (FBC) will also enhance the DC voltage by providing the constant voltage for the grid-connected inverter system. Secondly, the proposed RSTC controller will be monitoring voltage amplitude and frequency of grid power system. If any variation appears due to source power fluctuation, the controller will recognize it and automatically vary the pulse width modulation (PWM) of an inverter and compensate the grid power. The design analysis and operating approaches of the proposed converter are verified by MATLAB / Simulink 2017b. The performance analysis has been done with various parameters like total harmonics distortion (THD), steady-state error and converter efficiency.
Źródło:
Bulletin of the Polish Academy of Sciences. Technical Sciences; 2022, 70, 2; art. no. e140517
0239-7528
Pojawia się w:
Bulletin of the Polish Academy of Sciences. Technical Sciences
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
The effect of magnetic field dependent viscosity on ferromagnetic convection in a rotating sparsely distributed porous medium - revisited
Autorzy:
Prakash, J.
Kumar, P.
Manan, S.
Sharma, K. R.
Powiązania:
https://bibliotekanauki.pl/articles/265547.pdf
Data publikacji:
2020
Wydawca:
Uniwersytet Zielonogórski. Oficyna Wydawnicza
Tematy:
ferrofluid
konwekcja
pole magnetyczne
materiał porowaty
convection
rotation
magnetic field dependent viscosity
porous medium
Opis:
The effect of magnetic field dependent (MFD) viscosity on the thermal convection in a ferrofluid layer saturating a sparsely distributed porous medium has been investigated by using the Darcy-Brinkman model in the simultaneous presence of a uniform vertical magnetic field and a uniform vertical rotation. A correction is applied to the study of Vaidyanathan et al. [11] which is very important in order to predict the correct behavior of MFD viscosity. A linear stability analysis has been carried out for stationary modes and oscillatory modes separately. The critical wave number and critical Rayleigh number for the onset of instability, for the case of free boundaries, are determined numerically for sufficiently large values of the magnetic parameterM1 . Numerical results are obtained and are illustrated graphically. It is shown that magnetic field dependent viscosity has a destabilizing effect on the system for the case of stationary mode and a stabilizing effect for the case of oscillatory mode, whereas magnetization has a destabilizing effect.
Źródło:
International Journal of Applied Mechanics and Engineering; 2020, 25, 1; 142-158
1734-4492
2353-9003
Pojawia się w:
International Journal of Applied Mechanics and Engineering
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Dynamical analysis of stiffened plates under patch loading
Autorzy:
Srivastava, A. K. L.
Pandey, S. R.
Kumar, A.
Powiązania:
https://bibliotekanauki.pl/articles/265921.pdf
Data publikacji:
2013
Wydawca:
Uniwersytet Zielonogórski. Oficyna Wydawnicza
Tematy:
metoda elementów skończonych
obciążenie krawędziowe
częstotliwość drgań
usztywniacz
FEM
partial edge loadings
buckling load
vibration frequency
stiffener
Opis:
The vibration characteristics of stiffened plates with cutouts subjected to in-plane partial edge loadings at one end at the plate boundaries are studied using the finite element method. Buckling loads and vibration frequencies are determined for different cutout ratios and extent of partial edge loading at one end. In the structural modelling, the plate and the stiffeners are treated as separate elements where the compatibility between these two types of elements is maintained. The main elegance of the formulation lies in the treatment of the stiffeners. The stiffeners can be placed anywhere within the plate element, and need not be placed on the nodal lines. The vibration characteristics are discussed and the results are compared with those available in the literature. Numerical results are presented for a range of cutout to plate size from 0 to 0.8.
Źródło:
International Journal of Applied Mechanics and Engineering; 2013, 18, 2; 537-553
1734-4492
2353-9003
Pojawia się w:
International Journal of Applied Mechanics and Engineering
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Assessment of dental professionals’ maintenance of management practices developed and incorporated during COVID-19 pandemic – a cross-sectional study
Autorzy:
Singh, R.
Sekhon, T.
Sekhon, S.
Kumar, M.
Nirola, A.
Gambhir, R.S.
Powiązania:
https://bibliotekanauki.pl/articles/28765158.pdf
Data publikacji:
2023
Wydawca:
Narodowy Instytut Zdrowia Publicznego. Państwowy Zakład Higieny
Opis:
Background. COVID-19 pandemic has been a source of emerging public health problems for the past few years. Due to its contagious nature, health care professionals especially dentists, incorporated various modifications in their practices to prevent themselves and their patients from the risk of getting infected. Objective. The present study aims to assess whether dental professionals are still continuing with those modifications in practice in current times. Materials and Methods. The present study was conducted on 415 subjects after getting due approval from concerned authorities and consent from the subjects. Systematic random sampling methodology was employed for selection for study sample. The study employed a self-constructed questionnaire which was divided into 2 parts and information regarding demographic profile, practice modifications and safety protocols was gathered from subjects. Statistical analysis was conducted using Chi-square test and multiple regression analysis. Results. Only 8.6% of subjects were currently continuing with their all previous practice modifications. A vast majority of subjects (83.8%) were not deferring treatment of patients showing suspicious symptoms. Approximately 89% of subjects were not sanitizing the operating area at the end of the working day. More than two-thirds (76.4%) of the subjects stated that the pandemic was over. Female gender (OR:1.67) and high level of education (OR:2.45) had an important effect on the continuation of practice modifications. Conclusion. Very few subjects were adhering to all practice modifications previously incorporated. Dental professionals should not let their guard down even if COVID-19 cases have reduced considerably. The information collected will be useful for the dental community and further studies should be carried out.
Źródło:
Roczniki Państwowego Zakładu Higieny; 2023, 74, 3; 309-314
0035-7715
Pojawia się w:
Roczniki Państwowego Zakładu Higieny
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Photocatalytic degradation of ampicillin using silver nanoparticles biosynthesised by Pleurotus ostreatus
Autorzy:
Jassal, P.S.
Khajuria, R.
Sharma, R.
Debnath, P.
Verma, S.
Johnson, A.
Kumar, S.
Powiązania:
https://bibliotekanauki.pl/articles/2096973.pdf
Data publikacji:
2020
Wydawca:
Polska Akademia Nauk. Czytelnia Czasopism PAN
Tematy:
ampicillin
FTIR
photocatalysis
silver nanoparticles (Ag-NPs)
TEM
Opis:
The past few decades have witnessed a tremendous increase in the consumption of antibiotics worldwide. This rampant and unregulated use of antibiotics and their improper disposal has led to the accumulation of these drugs in the environment. This in turn has led to the emergence of antibiotic resistance in microbes and has become one of the most pressing global concerns in medicine, with highly resistant pathogens of many species proving difficult to treat. The aim of the study was to synthesise silver nanoparticles (Ag-NPs) using white rot fungus, Pleurotus ostreatus and assess its potential to carry out photocatalytic degradation of ampicillin. UV–Vis spectroscopy, Fourier transform infrared spectroscopy and transmission electron microscope have been used to characterize biosynthesized Ag-NPs. The photocatalytic degradation of ampicillin in aqueous solution by Ag-NPs was evaluated under natural sunlight. The effect of the operating conditions (contact time, Ag-NP concentration and initial ampicillin concentration) on the photocatalytic degradation was also investigated. The highest ampicillin degradation of 96.5% was observed after exposure of the solution (antibiotic + nanoparticles) for 4 h in sunlight. The maximum degradation was observed at an Ag-NP concentration of 5 ppm at pH 6. To the best of our knowledge, photocatalytic degradation of ampicillin using Ag-NPs synthesised by P. ostreatus has not been reported earlier.
Źródło:
BioTechnologia. Journal of Biotechnology Computational Biology and Bionanotechnology; 2020, 101, 1; 5-14
0860-7796
Pojawia się w:
BioTechnologia. Journal of Biotechnology Computational Biology and Bionanotechnology
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Knowledge, attitude and practice on exposure to Bisphenol A among dental surgeons in Southern India
Autorzy:
Kumar, H.A.
Soans, C.R.
Murali, P.S.
Ravi, R.S.
Shashidhar, K.
Shersha, S.
Powiązania:
https://bibliotekanauki.pl/articles/2082822.pdf
Data publikacji:
2021
Wydawca:
Narodowy Instytut Zdrowia Publicznego. Państwowy Zakład Higieny
Tematy:
knowledge
attitude
practice
Bisphenol A
composite
dental surgeons
Opis:
Background. Bisphenol A (BPA) is a product in the manufacture of Bis-GMA, which is commonly used in dentistry, and is known to have a number of adverse effects. Objectives. The aim of this study is to evaluate to assess the knowledge, attitude and practice based on exposure and handling of BPA containing materials among dental surgeons for better understanding about the level of care rendered to the patients. Material and methods. A questionnaire survey was conducted on 400 dental surgeons in Southern India. The questionnaire consisted of 20 objective type questions out of which ten questions assessed knowledge and five questions assessed the attitude and five questions to understand the practice related measures taken by the dentist. The data collected were analysed using SPSS version 23. Results. A total of 402 responses were collected for this online questionnaire survey over a period of 2 months. It was found that females showed higher knowledge and attitude towards exposure to BPA which was statistically significant when compared to males. It showed that dentists with more than 20 years of practice had a higher level of knowledge. Though most of the groups agreed fairly on safety practice to be undertaken related to BPA exposure in their clinics, the ones with experience more than 20 years displayed the least positive attitude and dentists with 6-10 years of practice had the least positive behaviour among all. Conclusions. In spite of having a good knowledge regarding the harmful effects of BPA, dental surgeons are not very cautious while using materials containing them on a regular basis. Therefore, there is a need to enhance the awareness with the help of Continuing Dental Education programs or proper instructions on the packaging.
Źródło:
Roczniki Państwowego Zakładu Higieny; 2021, 72, 4; 443-451
0035-7715
Pojawia się w:
Roczniki Państwowego Zakładu Higieny
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Influence of positions of the geotextile on the load-settlement behaviour of circular footing resting on single stone column by 2D Plaxis software
Autorzy:
Yadav, J. S.
Kumar, K.
Dutta, R. K.
Garg, A.
Powiązania:
https://bibliotekanauki.pl/articles/2055761.pdf
Data publikacji:
2021
Wydawca:
Stowarzyszenie Komputerowej Nauki o Materiałach i Inżynierii Powierzchni w Gliwicach
Tematy:
clay bed
circular footing
stone column
geotextile
numerical analysis
kolumny kamienne
geotkanina
analiza numeryczna
Opis:
Purpose: This study aims to study the load – settlement behaviour of circular footing rested on encased single stone column. Design/methodology/approach: The effect of vertical, horizontal and combined verticalhorizontal encasement of stone column on the load carrying capacity were examined numerically. The effect of stone column dimension (80 mm and 100 mm), length (400 mm and 500 mm), and spacing of reinforcement on the load carrying capacity and reinforcement ratio were assessed. Findings: The obtained results revealed that the load carrying capacity of geotextile encased stone columns are more than ordinary stone columns. For vertically encased stone columns as the diameter increases, the advantage of encasement decreases. Whereas, for horizontally encased stone column and combined vertical- horizontal encased stone column, the performance of encasement intensifies as the diameter of stone column increases. The improvement in the load carrying capacity of clay bed reinforced with combined verticalhorizontal encased stone columns are higher than vertical encased stone columns or horizontal encased stone column. The maximum performance of encasement was observed for VHESC1 of D = 80 mm. Research limitations/implications: For this study, the diameter of footing and stone column was kept same. The interface strength factor between stone column and clay bed was not considered. Practical implications: The encased stone column could be use improve the laod bearing capacity of weak soils. Originality/value: Many studies are available in literature regarding use of geosynthetic as vertical encasement and horizontal encasement of stone column. The study on combined effect of vertical and horizontal encasement of stone column on load carrying capacity of weak soil is very minimal. Keeping this in view, the present work was carried out.
Źródło:
Journal of Achievements in Materials and Manufacturing Engineering; 2021, 107, 2; 75--85
1734-8412
Pojawia się w:
Journal of Achievements in Materials and Manufacturing Engineering
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Influence of Rock Properties on Wear of M and SR Grade Rubber with Varying Normal Load and Sliding Speed
Autorzy:
Pal, S. K.
Rao, K. U. M.
Kumar, P. S.
Rajasekar, R.
Powiązania:
https://bibliotekanauki.pl/articles/356996.pdf
Data publikacji:
2017
Wydawca:
Polska Akademia Nauk. Czytelnia Czasopism PAN
Tematy:
rock
rubber
wear
shear strength
surface roughness
Opis:
Rubbers are interesting materials and are extensively used in many mining industries for material transportation. Wear of rubber is a very complex phenomenon to understand. The present study aims to explain the influence of rock properties on wear of M and SR grade rubber used in top cover of conveyor belts. Extensive laboratory experiments were conducted under four combinations of normal load and sliding speed. The wear of both the rubber types were analyzed based on the rock properties like shear strength, abrasivity index and fractal dimension. A fully instrumented testing set up was used to study the wear of rubber samples under different operating conditions. In general, wear was higher for M grade rubber compared to SR grade rubber. Increase in shear strength of rocks depicts decreasing trend for the wear of M and SR grade rubber at lower load conditions. Moreover, a higher load combination displays no definite trend in both the rubbers. The strong correlation between the wear of rubber and frictional power for all rubber-rock combinations has given rise to the parameter A, which reflects the relative compatibility between the rubber and rock. Increase of Cerchar’s Abrasivity Index of rocks shows gradual enhancement in wear for M grade rubber in all the load and speed combinations whereas, it fails in SR grade rubber due to its higher strength. The wear of rubber tends to decrease marginally with the surface roughness of rocks at highest normal load and sliding speed in M grade rubber. However, the wear of M and SR grade rubber is influenced by the surface roughness of rocks.
Źródło:
Archives of Metallurgy and Materials; 2017, 62, 3; 1787-1793
1733-3490
Pojawia się w:
Archives of Metallurgy and Materials
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Phytoremediation of heavy metals from paper mill effluent soil using Croton sparsiflorus
Autorzy:
Ashok Kumar, B
Jothiramalingam, S.
Thiyagarajan, S. K.
Hidhayathullakhan, T.
Nalini, R.
Powiązania:
https://bibliotekanauki.pl/articles/412059.pdf
Data publikacji:
2014
Wydawca:
Przedsiębiorstwo Wydawnictw Naukowych Darwin / Scientific Publishing House DARWIN
Tematy:
phytoremediation
heavy metals
effluent soil
croton sparsiflorus
Opis:
Effluents from industries contain appreciable amount of metallic cations like zinc, copper, iron, manganese, lead and cadmium. Release of heavy metal without proper treatment poses a significant threat to public health because of its persistence biomagnifications and accumulation in food chain. To reduce metal pollution problems many processes have been developed for the treatment and disposal of metal containing wastes. Certain plants have the ability to accumulate heavy metals such as Pb, Cr, Cd and Zn. At present, phytoremediation of metals may be approaching commercialization. Hence, possibility can be explored to remove heavy metal load, present even in low concentration, in waste water of paper mill effluent soil by using Croton sparsiflorus.
Źródło:
International Letters of Chemistry, Physics and Astronomy; 2014, 17, 1; 1-9
2299-3843
Pojawia się w:
International Letters of Chemistry, Physics and Astronomy
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Effect of electric field on dispersion of a solute in an MHD flow through a vertical channel with and without chemical reaction
Autorzy:
Umavathi, J. C.
Kumar, J. P.
Gorla, R. S. R.
Gireesha, B. J.
Powiązania:
https://bibliotekanauki.pl/articles/265686.pdf
Data publikacji:
2016
Wydawca:
Uniwersytet Zielonogórski. Oficyna Wydawnicza
Tematy:
dyspersja Taylora
magnetohydrodynamika
reakcja chemiczna
Taylor dispersion
immiscible fluids
conducting fluid
MHD
chemical reaction
Opis:
The longitudinal dispersion of a solute between two parallel plates filled with two immiscible electrically conducting fluids is analyzed using Taylor’s model. The fluids in both the regions are incompressible and the transport properties are assumed to be constant. The channel walls are assumed to be electrically insulating. Separate solutions are matched at the interface using suitable matching conditions. The flow is accompanied by an irreversible first-order chemical reaction. The effects of the viscosity ratio, pressure gradient and Hartman number on the effective Taylor dispersion coefficient and volumetric flow rate for an open and short circuit are drawn in the absence and in the presence of chemical reactions. As the Hartman number increases the effective Taylor diffusion coefficient decreases for both open and short circuits. When the magnetic field remains constant, the numerical results show that for homogeneous and heterogeneous reactions, the effective Taylor diffusion coefficient decreases with an increase in the reaction rate constant for both open and short circuits.
Źródło:
International Journal of Applied Mechanics and Engineering; 2016, 21, 3; 683-711
1734-4492
2353-9003
Pojawia się w:
International Journal of Applied Mechanics and Engineering
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Transforming distribution system into a sustainable isolatedmicrogrid considering contingency
Autorzy:
Hari Kumar, R.
Mayadevi, N.
Mini, V. P.
Ushakumari, S.
Powiązania:
https://bibliotekanauki.pl/articles/202424.pdf
Data publikacji:
2019
Wydawca:
Polska Akademia Nauk. Czytelnia Czasopism PAN
Tematy:
isolated microgrid
distributed generation
reliability
sustainability
prioritized load management
reconfiguration
Opis:
Currently, the distribution system has been adapted to include a variety of Distributed Energy Resources (DERs). Maximum benefits can be extracted from the distribution system with high penetration of DERs by transforming it into a sustainable, isolated microgrid. The key aspects to be addressed for this transformation are the determination of the slack bus and assurance of reliable supply to the prioritized loads even during contingency. This paper explores the possibilities of transforming the existing distribution system into a sustainable isolated net-work by determining the slack bus and the optimal locations and capacity of Distributed Generators (DGs) in the isolated network, taking into account the contingencies due to faults in the network. A combined sensitivity index is formulated to determine the most sensitive buses for DG placement. Further, the reliability based on the loss of load in the isolated system when a fault occurs is evaluated, and the modifications required in for reliability improvement are discussed. The supremacy of the transformed isolated network with distributed generators is comprehended by comparing the results from conventional IEEE 33-bus grid connected test system and modified IEEE 33-bus isolated test system having no interconnection with the main grid.
Źródło:
Bulletin of the Polish Academy of Sciences. Technical Sciences; 2019, 67, 5; 871-881
0239-7528
Pojawia się w:
Bulletin of the Polish Academy of Sciences. Technical Sciences
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Point Spread Function of Asymmetrically Apodized Optical Systems with Complex Pupil Filters: The One-Dimensional Case with Slit Aperture
Autorzy:
Keshavulu Goud, M.
Komala, R.
Naresh Kumar Reddy, A.
Goud, S.
Powiązania:
https://bibliotekanauki.pl/articles/1419735.pdf
Data publikacji:
2012-07
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
42.25.Fx
42.30.Kq
42.79.Ci
Opis:
Aimed at high resolution, an asymmetric point spread function has been obtained with good and bad sides by introducing three level asymmetric pupil functions. The good side has decreased side lobes while the bad side has increased side lobes. The asymmetry has been found to increase with the width of the edge strips within the slit aperture. On the other hand, there does not appear dependence of the asymmetry of the point spread function on the degree of amplitude apodization. But the magnitude of reduction of optical side-lobes is found to increase to a great extent by the amplitude apodization.
Źródło:
Acta Physica Polonica A; 2012, 122, 1; 90-95
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Parameter Characterization in Processing of Silver - Aluminum Based Electrical Contact Materials
Autorzy:
Praveen Kumar, S.
Parameshwaran, R.
Ananthi, A.
Jenil Jaba Sam, J.
Powiązania:
https://bibliotekanauki.pl/articles/352711.pdf
Data publikacji:
2017
Wydawca:
Polska Akademia Nauk. Czytelnia Czasopism PAN
Tematy:
electrical contactor
silver
aluminum
tin oxide
conduction
Opis:
An electrical contractor is one which plays significant role in day todays life in industries as well as in home appliances. In current scenario the materials for conducting purpose has an overwhelming research capability. Now a day the silver based electrical contact composite material have provided the potential applications in aerospace and automobile industries. Among silver based contact material the silver cadmium oxide and silver tin oxide plays a vital role in fabrication of electrical contactors. In this research an attempt has been made to study the influence of adding Aluminum with silver based electrical contact composite materials by two different processing routes namely stir-casting and powder metallurgy. Silver and aluminum matrix plays a virtual role in composite world owing to their highest conductivity. Optimum parameters were identified for attaining the maximum properties such as conductivity, hardness, density, and porosity of composition. By this better conducting property and mechanical property of the electrical contact can be improved by this system. Thus a screening test has be conducted with addition of Al with silver tin oxide compositions hence this paper aims to process the aluminum – silver based electrical contact materials by stir casting processing and powder metallurgy route and compare the results obtained.
Źródło:
Archives of Metallurgy and Materials; 2017, 62, 3; 1895-1901
1733-3490
Pojawia się w:
Archives of Metallurgy and Materials
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
An overview of current research trends on graphene and it’s applications
Autorzy:
Krishna, R. S.
Mishra, Jyotirmoy
Das, Shaswat Kumar
Mustakim, Syed Mohammed
Powiązania:
https://bibliotekanauki.pl/articles/1068613.pdf
Data publikacji:
2019
Wydawca:
Przedsiębiorstwo Wydawnictw Naukowych Darwin / Scientific Publishing House DARWIN
Tematy:
Concrete
Doping
Electrical
Graphene
Material
Mechanical
Properties
Sustainability
Opis:
Graphene is no doubt called a wonder-material due to its outstanding superlative traits. It has its application near about in every field. Its properties are extraordinary and different from any day-to-day material. Albeit bearing such qualities, its structure is rather simple than most individuals cerebrate of. It has a thickness of an atom. It is a two-dimensional carbon arranged in a honeycomb crystal structure. It could transmute the way we view, in numerous fields of science. Its applications can be an asset to a greener environment for which Graphene engineered cement/concrete composites have an immense potential in the present times when sustainable construction materials are the need of the hour. Graphene can act as a good adsorbent for pollutant abstraction due to its high surface area. Either alone or in coalescence with different materials, it very well may be used for the debasement or deliberation of a sizably voluminous assortment of contaminants through a few strategies. Incipient heights can be achieved as the list of operations for graphene is virtually illimitable. Utilization of graphene in the coming years will give inundating difference to current technologies. This paper fixates on the applications and developments of Graphene in fields like Electronics, Batteries, Filtration, Medicine, Construction, and Composites.
Źródło:
World Scientific News; 2019, 132; 206-219
2392-2192
Pojawia się w:
World Scientific News
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Salt effect on the enthalpy of mixing of 2-propanol + acetic acid at 303.15 K
Autorzy:
Tamilarasan, R.
Baffna, S.G.
Anand-Prabu, A.
Dharmendira-Kumar, M.
Powiązania:
https://bibliotekanauki.pl/articles/778859.pdf
Data publikacji:
2009
Wydawca:
Zachodniopomorski Uniwersytet Technologiczny w Szczecinie. Wydawnictwo Uczelniane ZUT w Szczecinie
Tematy:
entalpia
system binarny
efekt solny
2-propanol
kwas octowy
excess enthalpy
binary system
salt effect
acetic acid
Opis:
This paper presents the effect of two dissolved inorganic salts (zinc chloride, ZnCl2 and ammonium chloride, NH4Cl) on the enthalpy of mixing (HE) of 2-propanol + acetic acid binary system measured at 303.15 K using an isothermal displacement calorimeter with vapour space. A decreasing trend in the excess enthalpy of mixing values in the presence of ZnCl2 and NH4Cl indicate the endothermic behavior of this system. The Redlich-Kister equation has been used to fit the experimental HE data. The deviations from the ideal value and binary parameters were calculated and reported.
Źródło:
Polish Journal of Chemical Technology; 2009, 11, 4; 20-23
1509-8117
1899-4741
Pojawia się w:
Polish Journal of Chemical Technology
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Review on Parameters Influencing the Rice Breakage and Rubber Roll Wear in Sheller
Autorzy:
Prabhakaran, P.
Ranganathan, R.
Muthu Kumar, V.
Rajasekar, R.
Devakumar, L.
Pal, S. K.
Powiązania:
https://bibliotekanauki.pl/articles/351700.pdf
Data publikacji:
2017
Wydawca:
Polska Akademia Nauk. Czytelnia Czasopism PAN
Tematy:
rice
rice breakage
rubber roll sheller
Opis:
The present review deals with parameters influencing the rice breakage during rice milling operations and the effect of rubber roll Sheller in rice husk removal process. The main objective of rice milling system is to remove the husk and bran layer to produce the white rice. In this process, rubber roll sheller is used to remove husk from the grains by friction process. If the rubber material is too soft, there may not be sufficient shear force to husk the paddy. Wear will be minimum for rubber material with high hardness but indeed it pronounce the breakage of rice. Hence, for efficient husking the rubber roll material should possess the balance of physico-mechanical properties. Rice breakage depends on several other parameters like the type of harvest, drying temperature, drying methods, physical characteristics of paddy, husking characteristics, paddy moisture content, rubber roller speed, rubber roll pressure, paddy feed rate and fissures. Rubber roll wear depends on the type of rubber material attached to the roller, feed rate, roller speed, pressure etc.
Źródło:
Archives of Metallurgy and Materials; 2017, 62, 3; 1875-1880
1733-3490
Pojawia się w:
Archives of Metallurgy and Materials
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Prosthetic status and prosthetic needs amongst geriatric fishermen population of Kutch coast, Gujarat, India
Autorzy:
Kumar, D.R.V.
Raju, D.S.
Naidu, L.
Deshpande, S.
Chadha, M.
Agarwal, A.
Powiązania:
https://bibliotekanauki.pl/articles/874703.pdf
Data publikacji:
2015
Wydawca:
Narodowy Instytut Zdrowia Publicznego. Państwowy Zakład Higieny
Tematy:
geriatrics
prosthetic status
prosthetic need
fisherman
dental hygiene
dental health
environmental factor
oral health
human population
Kutch coast
Gujarat state
India
Opis:
Background. Literature among fishermen of India is scanty. The external factors like diet, quality of dental hygiene and environmental factors have an effect on oral health. Moreover elderly age group offer very little importance towards their oral health. Objective. To assess the prosthetic status and prosthetic treatment needs among the geriatric fishermen population of Kutch coast, Gujarat, India. Material and Methods. A cross sectional descriptive study was conducted among 1200 elderly people (above 60 years) of Kutch coast, Gujarat, India. They were interviewed and examined using a proforma designed with the help of WHO Oral Health Survey 1997. Chi square test was used for comparisons. Confidence level and p-value were set at 95% and 5% respectively. Results. Out of 1200 elderly people, 836 were males and 364 were females. Considering the prosthetic status, majority (76.7%) had no prosthesis followed by full removable dentures (12.3%). An insight into the prosthetic needs showed that majority (27.3%) had a need for multiunit prosthesis. Conclusion. In this study, it was seen that overall prosthetic status was low and prosthetic need was high. Therefore new avenues have to be discovered to make the prosthetic treatment readily available to the elderly.
Źródło:
Roczniki Państwowego Zakładu Higieny; 2015, 66, 2
0035-7715
Pojawia się w:
Roczniki Państwowego Zakładu Higieny
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Fabrication and Characterization of Al6061-Nano Al2O3 Composites by Ultrasonic Assisted Stir Casting followed by Heat Treatment and Hot Forging
Autorzy:
Purohit, Rajesh
Qureshi, M.M.U.
Kumar, Ashish
Mishra, Abhishek
Rana, R.S.
Powiązania:
https://bibliotekanauki.pl/articles/28099519.pdf
Data publikacji:
2023
Wydawca:
Polska Akademia Nauk. Czasopisma i Monografie PAN
Tematy:
Al6061 alloy
Al6061-Al2O3 nanocomposites
XRD analysis
FESEM
mechanical properties
automotive gears
Opis:
The present work comprises the development of Al6061/nano Al2O3 composites with 0 to 4 weight percent in steps of 0.5 wt. % of nano alumina particles by using ultrasonic assisted stir casting. Casted samples were subjected to heat treatment and hot forging. Further forged and heat-treated gear blanks of nano Al2O3 (0 to 3.0 weight %) reinforced nanocomposites were machined to make spur gears for the wear test. The results have shown that nano Al2O3 reinforcement in the Al6061 matrix with heat treatment and forging improves the hardness and compressive strength up to 3.5 wt. %, after that, it starts decreasing because of the agglomeration of nano alumina particles. SEM results reveal grain refinement of the pure alloy after reinforcement. Removal of porosity and voids observed after forging operation. Wear resistance increasing with incorporation of Al2O3 nanoparticles in base alloy, reinforcement wt. %, precipitation hardening and hot forging also improves wear resistance and mechanical properties. These composites have widespread applications in gear, brake discs, crankshaft, clutch plates, pistons, and other components of automobiles and aircraft structures.
Źródło:
Archives of Metallurgy and Materials; 2023, 68, 2; 791--798
1733-3490
Pojawia się w:
Archives of Metallurgy and Materials
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Biosorption of aniline blue from aqueous solution using a novel biosorbent Zizyphus oenoplia seeds: Modeling studies
Autorzy:
Kumar, M.
Elangovan, G
Tamilarasan, R
Vijayakumar, G.
Mukeshkumar, P. C.
Sendhilnathan, S.
Powiązania:
https://bibliotekanauki.pl/articles/778750.pdf
Data publikacji:
2015
Wydawca:
Zachodniopomorski Uniwersytet Technologiczny w Szczecinie. Wydawnictwo Uczelniane ZUT w Szczecinie
Tematy:
aniline blue
removal
biosorption
Zizyphus oenoplia seed
modeling
Opis:
This article presents the feasibility for the removal of Aniline Blue dye (AB dye) from aqueous solution using a low cost biosorbent material Zizyphus oenoplia seeds. In this study, a batch mode experiments of the adsorption process were carried out as a function of pH, contact time, concentration of dye, adsorbent dosage and temperature. The experimental data were fitted with Freundlich and Langmuir isotherm equations. The feasibility of the isotherm was evaluated with dimensionless separation factor (RL). The kinetic data of sorption process are evaluated by using pseudo-first order and pseudo-second order equations. The mode of diffusion process was evaluated with intra-particle diffusion model. The thermodynamic parameters like change in enthalpy (ΔHº); change in entropy (ΔSº) and Gibbs free energy change (ΔGº) were calculated using Van’t Hoff plot. The biosorbent material was characterized with Fourier Transform Infrared (FTIR) spectroscopy and the morphology was identified with Scanning Electron Microscope (SEM) in before and after adsorption of AB dye.
Źródło:
Polish Journal of Chemical Technology; 2015, 17, 3; 70-77
1509-8117
1899-4741
Pojawia się w:
Polish Journal of Chemical Technology
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
First tillodont from India: Additional evidence for an early Eocene faunal connection between Europe and India?
Autorzy:
Rose, K D
Rana, R.S.
Sahni, A.
Kumar, K.
Singh, L.
Smith, T.
Powiązania:
https://bibliotekanauki.pl/articles/22886.pdf
Data publikacji:
2009
Wydawca:
Polska Akademia Nauk. Instytut Paleobiologii PAN
Tematy:
paleontology
tillodont
India
Europe
Eocene
Paleocene
faunal connection
Cenozoic
mammal
Ypresian
anthracobunid
lagomorph
fauna
Opis:
Vastan Lignite Mine in southeastern Gujarat, India, produces the oldest known Cenozoic land−mammals and the only early Eocene continental vertebrate fauna known from India (e.g., Bajpai et al. 2005; Rana et al. 2005, 2008; Rose et al. 2006, 2008, 2009; Smith et al. 2007; Rage et al. 2008). The fauna comes from the Cambay Shale Formation and has been dated as middle Ypresian (~52 Ma, early Cuisian) based on a common nummulitid foraminiferan from about 15 m above the vertebrate−producing layer (Sahni et al. 2006; Rana et al. 2008). However, a recent study of dinoflagellate cysts from the section suggests that the deposits may be as old as 54–55 Ma (Garg et al. 2008). Although some elements of the fauna, such as anthracobunids and lagomorphs, have Asian affinities, a surprising number of taxa among the snakes, bats, insectivores, primates, rodents, and artiodactyls appear to be most closely related to early Eocene European or North American taxa. This may simply reflect the poor state of knowledge of contemporary south Asian vertebrate faunas; alternatively, it might be evidence of previously unsuspected early Eocene faunal exchange between Europe and southwest Asia. We report here two teeth of a tillodont from Vastan Mine, which constitute the first record of the mammalian order Tillodontia known from India. Despite the much greater generic diversity of tillodonts in Asia than elsewhere, the Vastan tillodont shows clear affinities with Euramerican esthonychines.
Źródło:
Acta Palaeontologica Polonica; 2009, 54, 2; 351-355
0567-7920
Pojawia się w:
Acta Palaeontologica Polonica
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Structural and Optical Behaviour οf~Ni Doped CdS Nanoparticles Synthesized by Chemical Co-Precipitation Method
Autorzy:
Siva Kumar, K.
Divya, A.
Sreedhara Reddy, P.
Uthanna, S.
Martins, R.
Elangovan, E.
Powiązania:
https://bibliotekanauki.pl/articles/1492639.pdf
Data publikacji:
2011-12
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
61.05.Cp
61.72.-y
78.55.Et
78.67.Bf
Opis:
Pure and Ni (2 at.%) doped cadmium sulfide (CdS) nanoparticles have been synthesized by chemical co-precipitation method at room temperature. Effect of Ni doping on CdS compound semiconductors has been analyzed using X-ray diffractometer, transmission electron microscope, energy dispersive spectroscopy, Raman and optical absorption studies. X-ray diffraction study confirmed the structure of the obtained nanoparticles to be single-phase zinc blende with the diffractions from (111), (220) and (311) planes. Energy dispersive spectroscopy study confirmed the presence of Ni in the CdS lattice. The average particle size obtained from the transmission electron microscopy studies are in agreement with the crystallite size calculated from X-ray diffraction data. The optical studies exhibited a clear red shift of absorption edge as a function of Ni doping.
Źródło:
Acta Physica Polonica A; 2011, 120, 6A; A-052-A-054
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Early Eocene frogs from Vastan Lignite Mine, Gujarat, India
Autorzy:
Folie, A.
Rana, R.S.
Rose, K.D.
Sahni, A.
Kumar, K.
Singh, L.
Smith, T.
Powiązania:
https://bibliotekanauki.pl/articles/20353.pdf
Data publikacji:
2013
Wydawca:
Polska Akademia Nauk. Instytut Paleobiologii PAN
Tematy:
Amphibia
Bombinatoridae
Ranidae
Pelobatidae
Rhacophoridae
Eocene
Early Eocene
frog
Vastan Lignite Mine
Gujarat
India
Opis:
The Ypresian Cambay Shale Formation of Vastan Lignite Mine in Gujarat, western India, has yielded a rich vertebrate fauna, including the earliest modern mammals of the Indian subcontinent. Here we describe its assemblage of four frogs, including two new genera and species, based on numerous, diverse and well−preserved ilia and vertebrae. An abundant frog, Eobarbourula delfinoi gen. and sp. nov., with a particular vertebral articulation similar to a zygosphene−zygantrum complex, represents the oldest record of the Bombinatoridae and might have been capable of displaying the Unken reflex. The large non−fossorial pelobatid Eopelobates, known from complete skeletons from the Eocene and Oligocene of Europe, is also identified at Vastan based on a single nearly complete ilium. An abundant “ranid” and a possible rhacophorid Indorana prasadi gen. and sp. nov. represent the earliest records of both families. The Vastan pelobatids and ranids confirm an early worldwide distribution of these families, and the bombinatorids and rhacophorids show possible origins of those clades on the Indian subcontinent.
Źródło:
Acta Palaeontologica Polonica; 2013, 58, 3
0567-7920
Pojawia się w:
Acta Palaeontologica Polonica
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Comparative evaluation of inversion approaches of the radiative transfer model for estimation of crop biophysical parameters
Autorzy:
Mridha, N.
Sahoo, R.N.
Sehgal, V.K.
Krishna, G.
Pargal, S.
Pradhan, S.
Gupta, V.K.
Nagesh Kumar, D.
Powiązania:
https://bibliotekanauki.pl/articles/25984.pdf
Data publikacji:
2015
Wydawca:
Polska Akademia Nauk. Instytut Agrofizyki PAN
Opis:
The inversion of canopy reflectance models is widely used for the retrieval of vegetation properties from remote sensing. This study evaluates the retrieval of soybean biophysical variables of leaf area index, leaf chlorophyll content, canopy chlorophyll content, and equivalent leaf water thickness from proximal reflectance data integrated broad bands corresponding to moderate resolution imaging spectroradiometer, thematic mapper, and linear imaging self scanning sensors through inversion of the canopy radiative transfer model, PROSAIL. Three different inversion approaches namely the look-up table, genetic algorithm, and artificial neural network were used and performances were evaluated. Application of the genetic algorithm for crop parameter retrieval is a new attempt among the variety of optimization problems in remote sensing which have been successfully demonstrated in the present study. Its performance was as good as that of the look-up table approach and the artificial neural network was a poor performer. The general order of estimation accuracy for para-meters irrespective of inversion approaches was leaf area index > canopy chlorophyll content > leaf chlorophyll content > equivalentleaf water thickness. Performance of inversion was comparable for broadband reflectances of all three sensors in the optical region with insignificant differences in estimation accuracy among them.
Źródło:
International Agrophysics; 2015, 29, 2
0236-8722
Pojawia się w:
International Agrophysics
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Investigation on the Effect of Technological Parameters on Emission Factor in 316L Stainless Steel Using Gas Metal Arc Welding
Autorzy:
Satheesh Kumar, K. V.
Selvakumar, P.
Uvanshankar, K. R.
Thirunavukaras, U. S.
Anand, Vijay V.
Vishal, D.
Powiązania:
https://bibliotekanauki.pl/articles/2049738.pdf
Data publikacji:
2021
Wydawca:
Polska Akademia Nauk. Czytelnia Czasopism PAN
Tematy:
emission factor
shielding gas
Permissible Exposure Limit
health hazards
glass fiber filter
Opis:
Growing awareness for occupational safety in the welding environment needs a sustainable welding system. Welding gases releases toxic tiny particles and gases that inflict severe health consequences in the weld zone are unsolicited. Some of the other main adverse effects are lung disease, hemoptysis, pulmonary inflammation, pneumoconiosis, etc. GMAW procedure has been used for welding 316L stainless steel plates of 3 mm, 5 mm, and 6 mm. Various current configurations with gas flow rate of 5 LPM, 10 LPM and 15 LPM were also used to achieve optimum butt joint performance and to reduce the production rate of fume contributing to cost-effectiveness. In this research a cost-effective fume extraction hood was fabricated for measuring emission factor produced during welding. Various shielding gas compositions including Pure Argon, Pure CO2, 92% Ar+8% CO2 and 88% Ar+12% CO2were used to determine the best operating parameters in the GMAW method. To satisfy the latest Permissible Exposure Limit (PEL) legislation, optimum technical parameters for efficient welding were acknowledged with the lowest emission factor. A maximum reduction of emission factor can be achieved by using Pure Argon. The inclusion of CO2 as a shielding gas mixture gives higher emission factor when compared to Pure Argon. Very low emission factor were witnessed in this research when compared to previous investigations. Lower emission factor of 2941.17 mg /kg of electrode, 4411.76 mg/kg of electrode and 7352.94 mg/kg of electrode were obtained for pure argon as shielding gas with 150 A welding current.
Źródło:
Archives of Metallurgy and Materials; 2021, 66, 2; 609-615
1733-3490
Pojawia się w:
Archives of Metallurgy and Materials
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Impact of heat treatment on the mechanical performance of hot extruded Al6061-BN reinforced metal matrix composites
Autorzy:
Mukesh, Y. B.
Naik, Prem Kumar
R, Raghavendra Rao
Vishwanatha, N. R.
Prema, N. S.
Girish, H. N.
Laxmana, Naik L.
Madhusudan, Puttaswamy
Powiązania:
https://bibliotekanauki.pl/articles/2086850.pdf
Data publikacji:
2021
Wydawca:
Polska Akademia Nauk. Czytelnia Czasopism PAN
Tematy:
Al 6061
metal matrix composites
boron nitride
heat treatment
hot extrusion
kompozyty z osnową metaliczną (MMC)
azotek boru
obróbka cieplna
wytłaczanie na gorąco
Opis:
Boron nitride (BN) reinforced Al6061 aluminum-based composites are synthesized by conventional stir casting method followed by exposure to hot extrusion. The optical images confirmed the distribution of BN nanoparticles in the aluminum alloy matrix. The concentration of BN is varied from (0.5, 1.5, 3, 4.5, 6, 7.5, and 9 wt%) in the composites and its effect on the tensile strength was investigated. The results revealed that both extruded and heat-treated composites specimens showed enhanced toughness and tensile strength by increasing BN nanoparticle concentration. The heat-treated composite samples showed lower flexibility of up to 40%, and further, it exhibited 37% greater hardness and 32% enhancement in tensile strength over the extruded sample. The tensile properties of Al6061-BN composites were evaluated by temperature-dependent internal friction (TDIF) analysis and the results showed that the as-prepared composite's strength increased with temperature.
Źródło:
Bulletin of the Polish Academy of Sciences. Technical Sciences; 2021, 69, 3; e137014, 1--6
0239-7528
Pojawia się w:
Bulletin of the Polish Academy of Sciences. Technical Sciences
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
An ailuravine rodent from the lower Eocene Cambay Formation at Vastan, western India, and its palaeobiogeographic implications
Autorzy:
Rana, R S
Kumar, K.
Escarguel, G.
Sahni, A.
Rose, K.D.
Smith, T.
Singh, H.
Singh, L.
Powiązania:
https://bibliotekanauki.pl/articles/23190.pdf
Data publikacji:
2008
Wydawca:
Polska Akademia Nauk. Instytut Paleobiologii PAN
Tematy:
Ischyromyidae
Cambay Formation
paleontology
Euromys inexpectatus
Euromys cardosoi
Rodentia
Eocene
India
Ailuravinae
Meldimys musak
Mammalia
ailuravine rodent
new species
Ailuravus michauxi
rodent
paleobiogeography
Western India
Opis:
A new ailuravine rodent, Meldimys musak sp. nov. (Mammalia: Rodentia, Ischyromyidae), is recorded from the lower Eocene lignites of western India. It is the oldest record of Rodentia from India. M. musak is more derived than the earliest Eocene ailuravine Euromys cardosoi from Portugal and more generalized than late early Eocene E. inexpectatus and Ailuravus michauxi from France. Its dental morphology closely corresponds to the middle early Eocene species M. louisi, which lived about 52 Ma in Western Europe. Meldimys was previously known only from Europe, and ailuravines were previously reported only from Europe and North America. Its occurrence in India allows the first direct correlation between the early Eocene land mammal horizons of Europe and India, and raises the possibility of a terrestrial faunal exchange between India and Eurasia close to the Palaeocene–Eocene transition.
Źródło:
Acta Palaeontologica Polonica; 2008, 53, 1
0567-7920
Pojawia się w:
Acta Palaeontologica Polonica
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Applicability of artificial intelligence in smart healthcare systems for automatic detection of Parkinson’s Disease
Autorzy:
Pallathadka, Harikumar
Padminivalli V., S.J.R.K.
Vasavi, M.
Nancy, P.
Naved, Mohd
Kumar, Harish
Ray, Samrat
Powiązania:
https://bibliotekanauki.pl/articles/38709253.pdf
Data publikacji:
2024
Wydawca:
Instytut Podstawowych Problemów Techniki PAN
Tematy:
Parkinson’s disease
detection
machine learning
relief algorithm
LDA algorithm
SVM-RBF
accuracy
sensitivity
specificity
choroba Parkinsona
wykrywanie
nauczanie maszynowe
algorytm ulgi
Algorytm LDA
dokładność
wrażliwość
specyficzność
Opis:
Parkinson’s disease is associated with memory loss, anxiety, and depression in the brain. Problems such as poor balance and difficulty during walking can be observed in addition to symptoms of impaired posture and rigidity. The field dedicated to making computers capable of learning autonomously, without having to be explicitly programmed, is known as machine learning. An approach to the diagnosis of Parkinson’s disease, which is based on artificial intelligence, is discussed in this article. The input for this system is provided through photographic examples of Parkinson’s disease patient handwriting. Received photos are preprocessed using the relief feature option to begin the process. This is helpful in the process of selecting characteristics for the identification of Parkinson’s disease. After that, the linear discriminant analysis (LDA) algorithm is employed to reduce the dimensions, bringing down the total number of dimensions that are present in the input data. The photos are then classified via radial basis function-support vector machine (SVM-RBF), k-nearest neighbors (KNN), and naive Bayes algorithms, respectively.
Źródło:
Computer Assisted Methods in Engineering and Science; 2024, 31, 2; 175-185
2299-3649
Pojawia się w:
Computer Assisted Methods in Engineering and Science
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Impact of heat treatment on the mechanical performance of hot extruded Al6061-BN reinforced metal matrix composites
Autorzy:
Mukesh, Y.B.
Naik, Prem Kumar
R, Raghavendra Rao
Vishwanatha, N.R.
Prema, N.S.
Girish, H.N.
Laxmana, Naik L.
Madhusudan, Puttaswamy
Powiązania:
https://bibliotekanauki.pl/articles/2128169.pdf
Data publikacji:
2021
Wydawca:
Polska Akademia Nauk. Czytelnia Czasopism PAN
Tematy:
Al 6061
metal matrix composites
boron nitride
heat treatment
hot extrusion
kompozyty z osnową metaliczną (MMC)
azotek boru
obróbka cieplna
wytłaczanie na gorąco
Opis:
Boron nitride (BN) reinforced Al6061 aluminum-based composites are synthesized by conventional stir casting method followed by exposure to hot extrusion. The optical images confirmed the distribution of BN nanoparticles in the aluminum alloy matrix. The concentration of BN is varied from (0.5, 1.5, 3, 4.5, 6, 7.5, and 9 wt%) in the composites and its effect on the tensile strength was investigated. The results revealed that both extruded and heat-treated composites specimens showed enhanced toughness and tensile strength by increasing BN nanoparticle concentration. The heat-treated composite samples showed lower flexibility of up to 40%, and further, it exhibited 37% greater hardness and 32% enhancement in tensile strength over the extruded sample. The tensile properties of Al6061-BN composites were evaluated by temperature-dependent internal friction (TDIF) analysis and the results showed that the as-prepared composite's strength increased with temperature.
Źródło:
Bulletin of the Polish Academy of Sciences. Technical Sciences; 2021, 69, 3; e137014, 1--6
0239-7528
Pojawia się w:
Bulletin of the Polish Academy of Sciences. Technical Sciences
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
The evaluation of weekly extended range river basin rainfall forecasts and a new bias correction mechanism for flood management in India
Autorzy:
Guhathakurta, Pulak
Prasad, Ashwini Kumar
Chattyopadhyay, Rajib
Sangwan, Neha
Wagh, Nilesh
Pattanaik, D. R.
Pai, D. S.
Mohapatra, M.
Powiązania:
https://bibliotekanauki.pl/articles/2058418.pdf
Data publikacji:
2022
Wydawca:
Instytut Meteorologii i Gospodarki Wodnej - Państwowy Instytut Badawczy
Tematy:
extended range prediction
rainfall bias correction
flood management
Opis:
Operational extended range forecasts are being disseminated once every week by the India Meteorological Department (IMD) for several sectorial applications. These forecasts show a reduction in amplitude and variance as a function of lead-time. Such reductions in variance can be due to several physical factors: inherent forecast model bias, a problem relating to initial conditions, leaddependent statistical biases, etc. A week-by-week analysis shows that such biases are not systematic. Rainfall forecasts are underestimated in some regions, while others overestimate rainfall amplitude. To correct the bias in the extended range weekly averaged forecast, a statistical post-processing method (normal ratio correction) is proposed to make the outlook more valuable at a longer lead-time. The correction method is based on the World Meteorological Organization (WMO) technical guidance on rainfall estimation and is also shown to be useful for rainfall forecasts. In this analysis, we evaluate the extended range forecast skill at the river sub-basin-scale and show that there are several river sub-basins over the central Indian region where the correction has improved the model forecast in the one to two-week range. Although this analysis was tailored toward making the river basins and sub-basins of India more readily realizable for flood forecasters, it can be used for any administrative boundaries such as block, district, or state-level requirements.
Źródło:
Meteorology Hydrology and Water Management. Research and Operational Applications; 2022, 10, 1; 1--25
2299-3835
2353-5652
Pojawia się w:
Meteorology Hydrology and Water Management. Research and Operational Applications
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Generation of shock waves in dense plasmas by high-intensity laser pulses
Autorzy:
Pasley, J.
Bush, I. A.
Robinson, A. P. L.
Rajeev, P. P.
Mondal, S.
Lad, A. D.
Ahmed, S.
Narayanan, V.
Ravindra Kumar, D
Kingham, R. J.
Powiązania:
https://bibliotekanauki.pl/articles/147346.pdf
Data publikacji:
2015
Wydawca:
Instytut Chemii i Techniki Jądrowej
Tematy:
shock waves
radiation hydrodynamics
laser–plasma interactions
fast ignition
inertial confinement fusion
Doppler spectroscopy
Opis:
When intense short-pulse laser beams (I > 1022 W/m2, τ < 20 ps) interact with high density plasmas, strong shock waves are launched. These shock waves may be generated by a range of processes, and the relative significance of the various mechanisms driving the formation of these shock waves is not well understood. It is challenging to obtain experimental data on shock waves near the focus of such intense laser–plasma interactions. The hydrodynamics of such interactions is, however, of great importance to fast ignition based inertial confinement fusion schemes as it places limits upon the time available for depositing energy in the compressed fuel, and thereby directly affects the laser requirements. In this manuscript we present the results of magnetohydrodynamic simulations showing the formation of shock waves under such conditions, driven by the j × B force and the thermal pressure gradient (where j is the current density and B the magnetic field strength). The time it takes for shock waves to form is evaluated over a wide range of material and current densities. It is shown that the formation of intense relativistic electron current driven shock waves and other related hydrodynamic phenomena may be expected over time scales of relevance to intense laser–plasma experiments and the fast ignition approach to inertial confi nement fusion. A newly emerging technique for studying such interactions is also discussed. This approach is based upon Doppler spectroscopy and offers promise for investigating early time shock wave hydrodynamics launched by intense laser pulses.
Źródło:
Nukleonika; 2015, 60, 2; 193-198
0029-5922
1508-5791
Pojawia się w:
Nukleonika
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Synthesis and evaluation of novel mri contrast agents of chemically modified GD-DTPA complexes with sugars
Autorzy:
Sugiyama, M.
Yamashita, M.
Yu, G.
Fujie, M.
Ogawa, K.
Ozaki, N.
Aoki, T.
Mizuno, S.
Okada, S.
Tachi, K.
Aoshima, K.
Sankar, U. R.
Kumar, B. S.
Takehara, Y.
Sakahara, H.
Powiązania:
https://bibliotekanauki.pl/articles/385252.pdf
Data publikacji:
2009
Wydawca:
Sieć Badawcza Łukasiewicz - Przemysłowy Instytut Automatyki i Pomiarów
Tematy:
MRI contrast agent
Gd(III)-DTPA
tumor imaging
Opis:
MRI is one of medical diagnostic imaging technologies that can draw the cross section in the body. To obtain a clearer image, Gd complexes are often used as MRI contrast agents. Gd-DTPA (Gd-Diethylenetriaminepentaacetate, Magnevist registered trademark ) is used in particular as the MRI contrast agents. We prepared and evaluated novel MRI contrast agents that were chemically modified Gd-DTPA with sugars (represented as Gd-DTPA-Sugar) via hydrolysis route for providing specificity to target organs and tissues. Gd-DTPASugar complex showed an excellent potential for the MRI contrast agent (r1=31.2 s-1mM-1). Gd-DTPA-Sugar complexes alternatively prepared by shorter synthetic route without protection/ deprotection (hydrolysis) method showed inferior results (r1=6.3 and 8.1 s-1mM-1) to the hydlized product.
Źródło:
Journal of Automation Mobile Robotics and Intelligent Systems; 2009, 3, 4; 191-194
1897-8649
2080-2145
Pojawia się w:
Journal of Automation Mobile Robotics and Intelligent Systems
Dostawca treści:
Biblioteka Nauki
Artykuł
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