PL
 |
EN
Preferencje help
Polish version English version Język
Widoczny [Schowaj] Abstrakt
Liczba wyników

Znaleziono wyników: 14

Liczba wyników na stronie
first rewind previous Strona / 1 next fast forward last
Wyniki wyszukiwania
help Sortuj według:

help Ogranicz wyniki do:
first rewind previous Strona / 1 next fast forward last
1
Content available Influence of positions of the geotextile on the load-settlement behaviour of circular footing resting on single stone column by 2D Plaxis software
Yadav J. S., Kumar K., Dutta R. K., Garg A.
Journal of Achievements in Materials and Manufacturing Engineering
|
2021
|
Vol. 107, nr 2
75--85
EN
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.
2
Content available Rheological behavior of fly ash suspension with additive for hydraulic conveyance
Kumar K.
International Journal of Applied Mechanics and Engineering
|
2020
|
Vol. 25, no. 2
202--210
EN
In the present work, rheological behaviour of a fine particulate fly ash slurry suspension is studied with and without addition of an additive. Rheological experiments are performed for the range of shear rate from 50 to 200 s1.Sodium sulfate is used as an additive in the fraction of 0.2, 0.4 and 0.6% (by weight). Addition of sodium sulfate to the fly ash slurry suspension leads to an improvement of its rheological characteristics. A reduction in relative viscosity and pressure drop is more pronounced with the addition of sodium sulfate in proportion of 0.4%, while marginal with 0.2 and 0.6% (by weight). The analysis reveals that the fly ash suspension has a potential to for being transported in a slurry pipeline with higher concentration and minimum energy consumption.
3
Content available remote Banes and boons of perturb & observe, incremental conductance and modified regula falsi methods for sustainable PV energy generation
Gopal Y., Kumar K., Birla D., Lalwani M.
Journal of Power Technologies
|
2017
|
Vol. 97, nr 1
35--43
EN
Maximum power point tracking (MPPT) optimizes overall power generation in photovoltaic (PV) applications. The voltagepower characteristics of PV array operating under variable irradiance and temperature conditions exhibit numerous local maximum power points (MPP). This paper presents the optimization method of MPP tracking, based on the modified Regula Falsi method (MRFM). Results of this method are compared with the conventional perturb & observe (P&O) method and the incremental conductance (IC) method. The modified Regula Falsi method has better convergence, lower oscillation time, less power loss and enhanced output power than the other two methods. To obtain a stable voltage from a solar array, a DC-DC Cuk converter is used. It can step-up and step-down the voltage level according to load requirement. Results have been verified on the MATLAB platform in variable environmental conditions.
4
Content available Reflection and transmission at the boundary surface of modified couple stress thermoelastic media
Kumar R., Kumar K.
International Journal of Applied Mechanics and Engineering
|
2016
|
Vol. 21, no. 1
61--81
EN
In this paper the reflection and transmission at a plane interface in modified couple stress generalized thermoelastic solid half spaces in the context of Loard-Shulman (LS) and Green-Lindsay (GL) theories in welded contact are investigated. Amplitude ratios of various reflected and transmitted waves are obtained due to incidence of a set of coupled longitudinal waves and coupled transverse waves. It is found that the amplitude ratios of various reflected and transmitted waves are functions of the angle of incidence, frequency and are affected by the couple stress properties of the media. Some special cases are deduced from the present formulation.
5
Content available Linear stability analysis for ferromagnetic fluids in the presence of magnetic field, compressibility, internal heat source and rotation through a porous medium
Kumar K., Singh V., Sharma S.
Journal of Theoretical and Applied Mechanics
|
2015
|
Vol. 53 nr 4
1067--1081
EN
The effects of magnetic field and heat source strength on thermal convection of a compressible rotating ferromagnetic fluid through a porous medium are investigated theoretically using linear stability theory. A normal mode analysis method is employed to find solutions for the fluid layer confined between parallel planes with free boundaries. The cases of stationary and oscillatory instabilities are discussed. For the stationary state, compressibility, medium porosity and temperature gradient due to heat source have destabilizing effects, whereas rotation and ratio of magnetic permeability delay the onset of convection. The magnetic field and medium permeability have both stabilizing and destabilizing effects under certain conditions. The variations in the stationary critical thermal Rayleigh number and neutral instability curves in (Ra1, x)-plane for various values of physical parameters are shown graphically to depict the stability characteristics. The sufficient conditions for the non-existence of overstability are obtained and the principle of exchange of stabilities holds true in the absence of magnetic field and rotation under certain conditions.
6
Content available remote On alternative methods of determining Radius of Curvature using Newton’s Rings set up
Raveesha K. H., Kumar K., Prasad B. K.
International Letters of Chemistry, Physics and Astronomy
|
2015
|
Vol. 48
27--31
EN
It well known that radius of curvature of a plano convex lens can be determined using Newton’s Rings set up making use of Interference by division of amplitude principle. The general method widely used involves measurement of diameter of several circular dark fringes. We propose two alternative methods involving different formulae. It is based on the fact that, the formation of bright and dark interference fringes is a measure of the thickness of the air film at that point. The methods use simpler geometry and the formulae are easier to derive. We present the experimental data. The results from the experiment are in agreement with results obtained through the general method.
7
Content available The dynamics of a parametrically driven damped pendulum
Das A., Kumar K.
International Journal of Applied Mechanics and Engineering
|
2015
|
Vol. 20, no. 2
257--266
EN
Ordered and chaotic states of a parametrically driven planar pendulum with viscous damping are numerically investigated. The damping makes the number of chaotic windows fewer but with larger width. Stroboscopic maps of the chaotic motion of the pendulum, driven either subharmonically or harmonically, show strange attractors with inversion symmetry in the phase plane.
8
Content available Synthesis, Complexation, Spectral and Antimicrobial Study of Some Novel 5-Bromo-2-Fluorobenzaldehydeoxime
Kumar K., Santhi N.
International Letters of Chemistry, Physics and Astronomy
|
2013
|
Vol. 3
46-52
EN
In this newly approached method a novel series of Transition metal complexes were synthesized by the reaction of 5-bromo-2-fluorobenzaldehyde (1) react with hydroxylamine in ethanolic solution at room temperature. Mononuclear complexes were synthesized by reaction with Cu(II) , Zn(II) and Hg(II) chloride salts. The complexes were characterized by elemental analysis, Ultraviolet, Infra -red and 1HNMR spectral studies. The antimicrobial activities of the ligand and its metal complexes were estimated.
9
Content available Road Traffic Noise Attenuation by Vegetation Belts at Some Sites in the Tarai Region of India
Tyagi V., Kumar K., Jain V. K.
Archives of Acoustics
|
2013
|
Vol. 38, No. 3
389--395
EN
Noise measurements have been carried out at eleven different sites located in three prominent cities of the Tarai region of India to evaluate the effectiveness of vegetation belts in reducing traffic noise along the roadsides. Attenuation per doubling of distance has been computed for each site and excess attenuation at different 1/3 octave frequencies has been estimated. The average excess attenuation is found to be approximately 15 dB over the low frequencies (200 Hz to 500 Hz) and between 15 dB to 20 dB over the high frequencies (8 kHz to 12.5 kHz). Over the critical middle frequencies (1-4 kHz), the average excess attenuation (between 10-15 dB) though not as high, is still significant, with a number of sites showing an excess attenuation of 15 dB or more at 1 kHz. The results indicate that sufficiently dense vegetation belts along the roadsides may prove as effective noise barriers and significant attenuation may be achieved over the critical middle frequencies (1-4 kHz).
10
Content available remote Wave propagation in couple stress thermoelastic half space underlying an inviscid liquid layer
Kumar R., Kumar K., Nautiyal R. C.
International Journal of Applied Mechanics and Engineering
|
2012
|
Vol. 17, no. 1
161-177
EN
The present paper is concerned with the propagation of waves in a couple stress elastic half space lying under an inviscid liquid layer in the context of Lord and Shulman (L-S) and Green and Lindsay (G-L) theories of thermoelasticity. It is observed that shear waves get decoupled from the rest of the motion. After developing the formal solution, the secular equations for surface wave propagation are derived. The dispersion curve giving the phase velocity and attenuation coefficient related to wave number are plotted graphically to depict the effect of thermal relaxation times. The amplitude ratios of displacement components and temperature distribution are also computed numerically and shown graphically to depict the effect of thermal relaxation times. Some special cases are also deduced from the present investigation.
11
Content available remote Stoneley waves at swelling porous elastic media
Kumar R., Taneja D., Kumar K.
International Journal of Applied Mechanics and Engineering
|
2012
|
Vol. 17, no. 4
1177-1192
EN
A frequency equation for Stoneley waves at a bonded interface between two swelling porous elastic half spaces [SP/SP] is derived. It is found that Stoneley waves in a swelling porous elastic medium are dispersive in nature. Numerical computations are performed to study the variation of phase velocity and attenuation coefficient with respect to the wave number. Amplitude ratios are obtained and also represented graphically. Some particular cases are also discussed.
12
Content available remote Wave propagation in swelling porous elastic layer
Kumar R., Taneja D., Kumar K.
International Journal of Applied Mechanics and Engineering
|
2011
|
Vol. 16, no 2
379-398
EN
The present investigation deals with the propagation of straight and circularly crested Lamb waves in a swelling porous elastic layer subjected to stress free boundary. A Helmholtz decomposition technique has been used to simplify the mathematical model. The secular equations for different mechanical situations are obtained. Numerical computations are performed to compute the symmetric and skew-symmetric phase velocity and attenuation coefficient in Swelling Porous (SP) and without Swelling Porous (elastic) (WSP) media. At short wavelength limits, the secular equations for symmetric and skew-symmetric waves in the stress free swelling porous and without swelling porous elastic layer reduce to the Rayleigh surface wave frequency equation. The amplitudes of displacements and stresses are obtained and are presented graphically. Some special cases have been deduced from the present investigation. The present study has immense applications to geophysical problems and structure problems.
13
Synthesis and Characterization of O,O'-Ditolyl-S-silylphosphorodithiolates
Kumar A., Kumar K., Pandey S. K.
Polish Journal of Chemistry
|
2009
|
Vol. 83, nr 12
2097-2104
EN
Reactions of SiCl4 or Me3SiCl with sodium ditolylphosphorodithioates, (o-, m- or p-MeC6H4O)2PS2Na, in different molar ratios in chloroform under anhydrous conditions, resulted in the formation of the compounds [{(o-, m- or p-MeC6H4O)2PS2}nSiCl4-n] (n = 1 or 2) or [(o-, m- or p-MeC6H4O)2PS2SiMe3] in 74-83% yield. These colorless, oily liquid compounds were characterized by elemental analysis, molecular weight determinations, IR and NMR (1H, 13C and 31P) spectroscopic studies, which revealed an unidentate mode of bonding of the dithiophosphate moiety with silicon atom, leading to a P-S-Si link age.
14
Content available remote Community annoyance from aircraft induced noise in Delhi
Sanyogita, Kumar K., Jain V. K.
Archives of Acoustics
|
2007
|
Vol. 32, No. 2
367-375
EN
Air traffic noise is a major cause of community annoyance in the residential areas near airports. The present study has been prompted by the need to examine the noise levels induced by the increased air traffic in Delhi in recent years. Noise levels have been measured in the indoor environment of two prominent residential areas of Delhi, namely, University Campus (UC) and Vasant Vihar (VV) which lie underneath the landing flight path of aircraft in Delhi. Spectral distributions show higher noise levels at lower frequencies and exhibit a declining trend with increase in frequency. With the help of spectral information, an index of aircraft noise, PNdB (perceived noise levels in decibels) is determined to assess relative annoyance or noisiness felt by the community of residential areas. PNdB values in the case of UC vary from a minimum of 66.7 to a maximum of 85.2. Further down the landing path, PNdB levels at VV are found to be appreciably higher in the range of 76.18-91.37. Results of social survey conducted to assess the community response to aircraft noise reveal that a majority (73%) of the respondents experience moderate to extreme annoyance. This is in conformity with the rather high PNdB values obtained for both the residential areas.
first rewind previous Strona / 1 next fast forward last
JavaScript jest wyłączony w Twojej przeglądarce internetowej. Włącz go, a następnie odśwież stronę, aby móc w pełni z niej korzystać.