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RISS 인기검색어
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- 저자 : Jagdev Singh (검색결과 4 건)
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Jatinder Gill,Jagdev Singh 대한설비공학회 2017 International Journal Of Air-Conditioning and Refr Vol.25 No.2
This paper presents an experimental analysis of a vapor compression refrigeration system (VCRS) using the mixture of R134a and LPGwith mass fractions of 28:72 as an alternative to R134a. In this work, we compare the energy performance of both refrigerants, R134a/LPG (28:72) and R134a, in a monitored vapor compression refrigeration system under a wide range of experimental conditions. So, the System with R134a/LPG (28:72) was tested by varying the capillary tube length and refrigerant charge under experimental conditions. Performance comparisons of both the systems are made taking refrigerant R134a as baseline, and the results show that the compressor power consumption, compressor discharge temperature and pull down time obtained with R134a/LPG (28:72) of 118 g and capillary tube length of 5.1 m in vapor compression refrigeration system are about 4.4% 2.4% and 5.3%, respectively, lower than that obtained with R134a in the studied range. Also, when using R134a/LPG (28:72), the system shows values of refrigeration capacity and COP are about 10.6% and 15.2% respectively, higher than those obtained using R134a, In conclusion, the mixing refrigerant R134a/LPG proposed in this study seems to be an appropriate long-term candidate to replace R134a as a new generation refrigerant of VCRS, because of its well environmentally acceptable properties and its favorable refrigeration performances.
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ANALYTICAL TECHNIQUES FOR SYSTEM OF TIME FRACTIONAL NONLINEAR DIFFERENTIAL EQUATIONS
최준상,Devendra Kumar,Jagdev Singh,Ram Swroop 대한수학회 2017 대한수학회지 Vol.54 No.4
We coupled the so-called Sumudu transform with the homotopy perturbation method (HPM) and the homotopy analysis method (HAM), which are called homotopy perturbation Sumudu transform \linebreak method (HPSTM) and homotopy analysis Sumudu transform method (HASTM), respectively. Then we show how HPSTM and HASTM are more convenient than HPM and HAM by conducting a comparative analytical study for a system of time fractional nonlinear differential equations. A Maple package is also used to enhance the clarity of the involved numerical simulations.
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ANALYTICAL TECHNIQUES FOR SYSTEM OF TIME FRACTIONAL NONLINEAR DIFFERENTIAL EQUATIONS
Choi, Junesang,Kumar, Devendra,Singh, Jagdev,Swroop, Ram Korean Mathematical Society 2017 대한수학회지 Vol.54 No.4
We coupled the so-called Sumudu transform with the homotopy perturbation method (HPM) and the homotopy analysis method (HAM), which are called homotopy perturbation Sumudu transform method (HPSTM) and homotopy analysis Sumudu transform method (HASTM), respectively. Then we show how HPSTM and HASTM are more convenient than HPM and HAM by conducting a comparative analytical study for a system of time fractional nonlinear differential equations. A Maple package is also used to enhance the clarity of the involved numerical simulations.
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Mid-term quasi-periodicities in the CaII-K plage index of the Sun and their implications
Chowdhury, Partha,Gokhale, M. H.,Singh, Jagdev,Moon, Y.-J. D. Reidel 2016 Astrophysics and space science Vol.361 No.2
<P>We present results of the fast Fourier transform (FFT), the MEM analysis, and the wavelet analysis (WA), of the temporal variation of the monthly disk integrated 'CaII-K plage-area and enhanced network (EN) area' hereafter called 'plage index' derived by Tlatov et al. (2009), from spectro-heliograms taken in Ca II K line at Kodaikanal Observatory, from February 1907 to April, 1998, In the range >3 months and < decade, the Fourier transform power spectra reveal solar cycle periodicity similar to 122 months, its sub-harmonic similar to 61 months, two short quasi-periodicities (>2 and <4 months), and nine 'intermediate-range' quasi-periodicities (greater than or similar to 4 mo and <11 yr), in the variation of the plage index. The quasi-periodicities include Rieger, Rieger type and quasi-biennial. The presence of quasi-periodicities and the mean values of the periods are confirmed by the maximum entropy method (MEM). The temporal spans of the quasi-periodicities during different solar cycles are determined from the complex Morlet-wavelet analyses. The Rieger quasi-periodicity (150-160 days) appeared during cycle 21 and cycle 22. Each of the quasi-periodicities in the studied range lies close to one or more planetary periodicities (orbital, or spring tidal, or heliocentric conjunction frequency). We discuss possible interpretations of our results, and those of similar results obtained earlier by other authors, towards understanding the mechanisms of excitation of various quasi-periodicities detected in solar variability parameters.</P>
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