Autor: Yadav, S. - Katalog OPAC zbiorów

Skocz do pozycji: 1.

Tytuł:: Stokes flow around slowly rotating concentric previous spheres
Przepływ stokesowski wokół powolnie wirujących koncentrycznych kul przepuszczalnych
Autorzy:: Srivastava, D. K.
Yadav, R. R.
Yadav, S.
Powiązania:: https://bibliotekanauki.pl/articles/140159.pdf
Data publikacji:: 2013
Wydawca:: Polska Akademia Nauk. Czytelnia Czasopism PAN
Tematy:: rotation of concentric spheres
fluid sink
slow viscous flow
Stokes approximation
wirowanie kul koncentrycznych
zlew płynu
lepki powolny przepływ
aproksymacja Stokes'a
Opis:: In this paper, the problem of concentric pervious spheres carrying a fluid sink at their centre and rotating slowly with different uniform angular velocities Ω₁, Ω₂ about a diameter has been studied. The analysis reveals that only azimuthal component of velocity exists and the torque, rate of dissipated energy is found analytically in the present situation. The expression of torque on inner sphere rotating slowly with uniform angular velocity Ω₁, while outer sphere also rotates slowly with uniform angular velocity Ω₂, is evaluated. The special cases like, (i) inner sphere is fixed (i.e. Ω₁ = 0), while outer sphere rotates with uniform angular velocity Ω₂, (ii) outer sphere is fixed (i.e. Ω₂ = 0), while inner sphere rotates with uniform angular velocity Ω₁, (iii.) inner sphere rotates with uniform angular velocity Ω₁, while outer rotates at infinity with angular velocity Ω₂; have been deduced. The corresponding variation of torque with respect to sink parameter has been shown via figures. AMS subject classification – 76 D07.
W artykule rozważa się problem koncentrycznych kul przepuszczalnych, ze zlewem płynu w centrum, które wirują powoli wokół średnicy z jednostajnymi prędkościami kątowymi Ω₁ i Ω₂. Analiza wykazała, że istnieje tylko azymutalny składnik prędkości, a moment obrotowy i szybkość rozpraszania energii są w istniejących warunkach wyznaczane analitycznie. Wyprowadzono wyrażenie na moment obrotowy na powierzchni wewnętrznej kuli powolnie wirującej z jednostajną prędkością kątową Ω₁, podczas gdy kula zewnętrzna także powolnie wiruje z jednostajną prędkością kątową Ω₂. Zbadano także przypadki szczególne, takie jak: (i) kula wewnętrzna jest nieruchoma (tzn. Ω₁ = 0), podczas gdy kula zewnętrzna wiruje z jednostajną prędkością kątową Ω₂, (ii) kula zewnętrzna jest nieruchoma (tzn. Ω₂ = 0), podczas gdy kula wewnętrzna wiruje z jednostajną prędkością kątową Ω₁, (iii) kula wewnętrzna wiruje z jednostajną prędkością kątową Ω₁, podczas gdy kula zewnętrzna wiruje w nieskończonej odległości z prędkością kątową Ω₂. Na wykresach przedstawiono zależności między zmianami momentu obrotowego a parametrami zlewu.
Źródło:: Archive of Mechanical Engineering; 2013, LX, 2; 165-184
0004-0738
Pojawia się w:: Archive of Mechanical Engineering
Dostawca treści:: Biblioteka Nauki

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Skocz do pozycji: 2.

Tytuł:: Steady Oseen’s flow past a deformed sphere: an analytical approach
Autorzy:: Srivastava, D. K.
Yadav, R. R.
Yadav, S.
Powiązania:: https://bibliotekanauki.pl/articles/280226.pdf
Data publikacji:: 2013
Wydawca:: Polskie Towarzystwo Mechaniki Teoretycznej i Stosowanej
Tematy:: Stokes drag
Oseen’s drag
axially symmetric arbitrary body
axial flow
Opis:: In a recent authors’ paper, the general expression of Stokes drag experienced by a deformed sphere in both longitudinal and transverse flow situations was calculated in terms of the deformation parameter up to the second order. In this paper, Oseen’s correction to the axial Stokes drag on the deformed sphere is presented by using Brenner’s formula in general, first and then applied to prolate and oblate the deformed spheroid up to the second order of the deformation parameter. Numerical values of Oseen’s correction is obtained with respect to the deformation parameter and Reynolds number. The corresponding variations are depicted in figures. Some particular cases of a needle shaped body and flat circular disk are considered and found to be in good agreement with those existing in the literature. The import ant applications are also highlighted.
Źródło:: Journal of Theoretical and Applied Mechanics; 2013, 51, 3; 661-673
1429-2955
Pojawia się w:: Journal of Theoretical and Applied Mechanics
Dostawca treści:: Biblioteka Nauki

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Skocz do pozycji: 3.

Tytuł:: Electro-Optical Behavior of Dye Doped Nematic Liquid Crystal
Autorzy:: Yadav, S.
Pandey, K.
Misra, A.
Manohar, R.
Powiązania:: https://bibliotekanauki.pl/articles/1505061.pdf
Data publikacji:: 2011-06
Wydawca:: Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:: 64.70.M-
42.79.Kr
Opis:: We report electro-optical behavior of a dye doped nematic liquid crystal. The dye doped cells have shown some improvement in some parameters important for the display devices such as threshold voltage $(V_{th})$, splay elastic constant, rotational viscosity and response time. The suppression of screening effect improves the threshold voltage for the doped sample.
Źródło:: Acta Physica Polonica A; 2011, 119, 6; 824-828
0587-4246
1898-794X
Pojawia się w:: Acta Physica Polonica A
Dostawca treści:: Biblioteka Nauki

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Skocz do pozycji: 4.

Tytuł:: A study on alkali resistant glass fibre concrete and its exposure to elevated temperatures
Autorzy:: Hussain, S.
Yadav, J. S.
Powiązania:: https://bibliotekanauki.pl/articles/1818818.pdf
Data publikacji:: 2020
Wydawca:: Stowarzyszenie Komputerowej Nauki o Materiałach i Inżynierii Powierzchni w Gliwicach
Tematy:: alkali resistant glass fibres
accelerated carbonation
compressive strength
thermogravimetric analysis
scanning electron microscopy
split tensile strength
włókna szklane
alkalia
karbonatyzacja
przyspieszenie
wytrzymałość na ściskanie
analiza termograwimetryczna
skaningowa mikroskopia elektronowa
wytrzymałość na rozciąganie
Opis:: Purpose: Cement concrete is characterized as brittle in nature, the loading capacity of which is completely lost once failure is initiated. This characteristic, which limits the application of the material, can in one way be overcome by the addition of some small amount of short randomly distributed fibers (steel, glass, synthetic). Design/methodology/approach: The present study deals with the inclusion of alkali resistant glass fibers in concrete by percentage weight of cement. The mechanical properties such as compressive strength and split tensile strength have been studied after exposing the concrete samples to elevated temperatures of up to 500°C. Water binder ratios of 0.4, 0.45, 0.5, 0.55 and 0.6 have been used to prepare design mix proportions of concrete to achieve a characteristic strength of 30 MPa. The depth of carbonation post elevated temperature exposure has been measured by subjecting the concrete samples to an accelerated carbonation (5%) condition in a controlled chamber. Findings: Conclusions have been drawn in accordance to the effect of fiber replacement and temperature increment. The concrete mixes with fiber content of 1% by weight of cement had shown better strength in compression and tension compared to the other dosages and conventional concrete (without fiber). Microcracking due to internal stream pressure reduced the mechanical strengths of concrete at elevated temperatures. Also, from TGA it was observed that the amount of calcium carbonate in samples with fiber added, post carbonation was less than the mixes without fiber in it. Research limitations/implications: The present study has been limited to alkali resistant glass fibers as the conventional glass fibers undergo corrosion due to hydration. Practical implications: The glass fiber reinforced concrete can be used in the building renovation works, water and drainage works, b ridge and tunnel lining panels etc. Originality/value: Based upon the available literature, very seldom the studies are addressing the behaviour of alkali resistant glass fiber concrete and its exposure to elevated temperatures.
Źródło:: Journal of Achievements in Materials and Manufacturing Engineering; 2020, 103, 1; 5--15
1734-8412
Pojawia się w:: Journal of Achievements in Materials and Manufacturing Engineering
Dostawca treści:: Biblioteka Nauki

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Skocz do pozycji: 5.

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

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Skocz do pozycji: 6.

Tytuł:: Simplified analyses of stress induced anisotropy in remolded soft clay under undrained conditions
Autorzy:: Lin, P.
Li, Z.-x.
Garg, A.
Yadav, J. S.
Powiązania:: https://bibliotekanauki.pl/articles/1818489.pdf
Data publikacji:: 2020
Wydawca:: Stowarzyszenie Komputerowej Nauki o Materiałach i Inżynierii Powierzchni w Gliwicach
Tematy:: stress induced anisotropy
Shantou soft clay
true triaxial experiment
anizotropia wywołana naprężeniem
miękka glinka Shantou
prawdziwy eksperyment trójosiowy
Opis:: Purpose: The soil’s anisotropy induced by stress (i.e. stress induced anisotropy) has an important effect on the behavior of soil. This paper focuses on analyzing the anisotropy of remolded Shantou soft clay under compression stress path. Design/methodology/approach: Experiments were executed by using three axle experimental instruments. The data obtained from the plain strain tests were analyzed and the relationship between stress and strain was calculated by using the modified Duncan- Chang and Lade-Duncan models. The models were modified under the condition of plain strain and cohesion. Findings: It was concluded that in complex stress path conditions, the conventional triaxial tests may not fully reflect the actual stress of soil and its response in the Duncan-Chang and Lade-Duncan models. Research limitations/implications: The formulation of Mohr-Coulomb failure criterion in the plasticity framework is quite diffcult. As a result, dilatancy cannot be described. The properties of soil in unload or drained conditions remain to be part of further investigated. Practical implications: Based upon the two stiffness parameters, the modified Duncan- Chang model has captured the soil behaviour in a very conformable way and is recommened for practical modeling. These constitutive models of soil are widely used in the numerical analyses of soil structure such as embankments. Originality/value: Duncan-Chang and Lade-Duncan models widely used in engineering practices are modes based on conventional triaxial cases. Both models have have some inherent limitations to represent the stress-strain characteristics of soils, such as shear-induced dilatancy and stress path dependency and required corrections. In this investigation, the tests are carried out in undrained conditions. It is related to the properties of soil in load conditions.
Źródło:: Archives of Materials Science and Engineering; 2020, 105, 2; 56--64
1897-2764
Pojawia się w:: Archives of Materials Science and Engineering
Dostawca treści:: Biblioteka Nauki

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Skocz do pozycji: 7.

Tytuł:: Effect of van Hove Singularity on T$\text{}_{c}$ in Rb doped C$\text{}_{60}$
Autorzy:: Agrawal, B. K.
Agrawal, S.
Yadav, P. S.
Srivastava, P.
Srivastava, R.
Singh, S.
Powiązania:: https://bibliotekanauki.pl/articles/2035748.pdf
Data publikacji:: 2003-05
Wydawca:: Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:: 74.25.Jb
74.62.Fj
74.70.Wz
Opis:: In the present study we investigate the role of van Hove singularity on the optimization of T$\text{}_{c}$ in Rb doped fullerenes C$\text{}_{60}$ Rb$\text{}_{3}$. A first principles self-consistent full potential linear muffin-tin orbital method using density functional theory in local density approximation was employed. The doped Rb atoms are of two types occupying the tetrahedral and interstitial positions in the fcc lattice. The added Rb atoms fill the t$\text{}_{1u}$ band of the undoped fullerenes C$\text{}_{60}$ up to half which makes C$\text{}_{60}$Rb$\text{}_{3}$ conducting. Saddle points leading to van Hove singularities are observed in the neighbourhood of the symmetry point L. The shifting of the van Hove singularity with the volume of the lattice is investigated. We observe a saddle point just at the Fermi level for a lattice constant of 14.435Å. The highest value of T$\text{}_{c}$ should thus be observed at the above lattice constant. This result is in excellent agreement with the observed high value of T$\text{}_{c}$ measured in C$\text{}_{60}$Rb$\text{}_{3}$ for a lattice constant of 14.435Å.
Źródło:: Acta Physica Polonica A; 2003, 103, 5; 477-482
0587-4246
1898-794X
Pojawia się w:: Acta Physica Polonica A
Dostawca treści:: Biblioteka Nauki

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Skocz do pozycji: 8.

Tytuł:: Amplitude Modulation and Demodulation in Strain Dependent Diffusive Semiconductors
Autorzy:: Ghosh, S.
Yadav, N.
Powiązania:: https://bibliotekanauki.pl/articles/2047356.pdf
Data publikacji:: 2007-07
Wydawca:: Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:: 52.35.Mw
72.50.+b
66.30.-h
Opis:: In communication processes, amplitude modulation is very helpful to save power by using a single band transmission. Thus in this paper authors have explored the possibility of amplitude modulation as well as demodulation of an electromagnetic wave in a transversely magnetized electrostrictive semiconductor. The inclusion of carrier diffusion and phenomenological damping coefficient in the nonlinear laser-semiconductor plasma interaction adds a new dimension to the analysis present in this paper. This problem is analyzed in different wave number regimes over a wide range of cyclotron frequencies. It is found that the complete absorption of the waves takes place in all the possible wavelength regimes when the cyclotron frequency (ω$\text{}_{c}$) becomes exactly equal to (ν$\text{}^{2}$+ω$\text{}_{0}^{2}$)$\text{}^{1}\text{}^{/}\text{}^{2}$ in absence of damping parameter. It has also been seen that diffusion of charge carriers modifies amplitude modulation and demodulation processes significantly. The damping parameter plays a very important role in deciding the parameter range and selecting the side band mode that will be modulated by the above-mentioned interaction.
Źródło:: Acta Physica Polonica A; 2007, 112, 1; 29-40
0587-4246
1898-794X
Pojawia się w:: Acta Physica Polonica A
Dostawca treści:: Biblioteka Nauki

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Skocz do pozycji: 9.

Tytuł:: Assessing the suitability of extreme learning machines (ELM) for groundwater level prediction
Ocena zdolności ekstremalnych maszyn uczących (ELM) do przewidywania poziomu wód gruntowych
Autorzy:: Yadav, B.
Ch, S.
Mathur, S.
Adamowski, J.
Powiązania:: https://bibliotekanauki.pl/articles/293096.pdf
Data publikacji:: 2017
Wydawca:: Instytut Technologiczno-Przyrodniczy
Tematy:: extreme learning machine (ELM)
forecasting
groundwater level
support vector machine (SVM)
water resource management
maszyna uczenia ekstremalnego (ELM)
maszyna wektorów nośnych SVM
poziom wód gruntowych
prognozowanie
zarządzanie zasobami wodnymi
Opis:: Fluctuation of groundwater levels around the world is an important theme in hydrological research. Rising water demand, faulty irrigation practices, mismanagement of soil and uncontrolled exploitation of aquifers are some of the reasons why groundwater levels are fluctuating. In order to effectively manage groundwater resources, it is important to have accurate readings and forecasts of groundwater levels. Due to the uncertain and complex nature of groundwater systems, the development of soft computing techniques (data-driven models) in the field of hydrology has significant potential. This study employs two soft computing techniques, namely, extreme learning machine (ELM) and support vector machine (SVM) to forecast groundwater levels at two observation wells located in Canada. A monthly data set of eight years from 2006 to 2014 consisting of both hydrological and meteorological parameters (rainfall, temperature, evapotranspiration and groundwater level) was used for the comparative study of the models. These variables were used in various combinations for univariate and multivariate analysis of the models. The study demonstrates that the proposed ELM model has better forecasting ability compared to the SVM model for monthly groundwater level forecasting.
Na całym świecie fluktuacje poziomów wód gruntowych stanowią ważny temat badań hydrologicznych. Rosnące potrzeby wodne, błędne praktyki irygacyjne, niewłaściwa gospodarka glebowa i niekontrolowana eksploatacja poziomów wodonośnych są powodami, dla których poziom wód gruntowych podlega fluktuacjom. Dla skutecznego zarządzania zasobami wód gruntowych istotne jest dysponowanie dokładnymi zapiskami i zdolność prognozowania poziomu tych wód. Rozwój technik komputerowych (modele wykorzystujące dane) w dziedzinie hydrologii ma istotny potencjał z powodu niepewnego i złożonego charakteru systemów wód gruntowych. W prezentowanych badaniach wykorzystano dwie techniki komputerowe: maszynę uczenia ekstremalnego (ELM) i maszynę wektorów nośnych (SVM – ang. support vector machine) do przewidywania poziomów wód gruntowych w dwóch studzienkach obserwacyjnych w Kanadzie. Do porównawczych badań modeli wykorzystano zestaw danych miesięcznych z ośmiu lat (2006–2014), składający się z danych hydrologicznych i meteorologicznych (opady, temperatura, ewapotranspiracja, poziom wody). Wymienione zmienne zastosowano w rozmaitych kombinacjach do jedno- i wieloparametrycznej analizy modeli. Wyniki dowodzą, że model ELM ma lepsze zdolności przewidywania miesięcznych poziomów wód gruntowych w porównaniu z modelem SVM.
Źródło:: Journal of Water and Land Development; 2017, 32; 103-112
1429-7426
2083-4535
Pojawia się w:: Journal of Water and Land Development
Dostawca treści:: Biblioteka Nauki

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Skocz do pozycji: 10.

Tytuł:: Effect of demand boosting policy on optimal inventory policy for imperfect lot size with backorder in fuzzy environment
Autorzy:: Yadav, D.
Singh, S. R.
Kumari, R.
Powiązania:: https://bibliotekanauki.pl/articles/206244.pdf
Data publikacji:: 2012
Wydawca:: Polska Akademia Nauk. Instytut Badań Systemowych PAN
Tematy:: learning curve
advertisement
signed distance
triangular fuzzy number
backorder
inventory model
Opis:: This paper investigates an Economic Order Quantity (EOQ) model with backorder by taking imprecise demand rate with dependence upon the frequency of advertisement. The formulated model also incorporates learning effects on percentage of defective items present in each lot. Due to imprecision in demand, the obtained profit function is fuzzy. To determine the optimal values, we determine the equivalent crisp profit function by applying the signed distance method. Optimal order quantity and backorder level are obtained by using algebraic method in place of differential calculus. A numerical example is used to study the behavior of the model with respect to different inventory parameters. All calculations are performed with MATLAB 7.4.
Źródło:: Control and Cybernetics; 2012, 41, 1; 191-212
0324-8569
Pojawia się w:: Control and Cybernetics
Dostawca treści:: Biblioteka Nauki

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