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41.
We investigate the validity of the generalized second law of gravitational thermodynamics in a non-flat FRW universe containing
the interacting generalized Chaplygin gas with the baryonic matter. The boundary of the universe is assumed to be enclosed
by the dynamical apparent horizon. We show that for the interacting generalized Chaplygin gas as a unified candidate for dark
matter and dark energy, the equation of state parameter can cross the phantom divide. We also present that for the selected
model under thermal equilibrium with the Hawking radiation, the generalized second law is always satisfied throughout the
history of the universe for any spatial curvature, independently of the equation of state of the interacting generalized Chaplygin
gas model. 相似文献
42.
K. Karami 《Astrophysics and Space Science》2009,319(1):37-44
Here the effect of rotation up to third order in the angular velocity of a star on the p, f and g modes is investigated. To
do this, the third-order perturbation formalism presented by Soufi et al. (Astron. Astrophys. 334:911, 1998) and revised by Karami (Chin. J. Astron. Astrophys. 8:285, 2008), was used. I quantify by numerical calculations the effect of rotation on the oscillation frequencies of a uniformly rotating
β-Cephei star with 12 M
⊙. For an equatorial velocity of 90 km s−1, it is found that the second- and third-order corrections for (l,m)=(5,−4), for instance, are of order of 0.07% of the frequency for radial order n=−3 and reaches up to 0.6% for n=−20. 相似文献
43.
The standing magnetohydrodynamic (MHD) quasi-linear modes in a zero-β cylindrical magnetic flux tube that undergoes a longitudinal density stratification and radial density structuring are considered. The radial structuring is assumed to have a step-like density profile. The dispersion relation for the fast MHD body waves is derived and solved numerically to obtain the frequencies of the fundamental, first-overtone and second-overtone k = 1, 2, 3 modes of both kink ( m = 1) and fluting ( m = 2) waves, where k and m are the longitudinal and azimuthal mode numbers, respectively. Damping rates due to both viscous and resistive dissipations in the presence of the density stratification are derived and solved numerically for the first three modes of both kink and fluting waves. 相似文献
44.
We introduce a new method to derive the orbital parameters of spectroscopic binary stars by a non-linear least squares analysis
of residuals. Using measured radial velocity data of four double lined spectroscopic binary systems RZ Cas, CC Cas, V1130
Tau and Y Cygni, we find corresponding orbital and spectroscopic elements. Our numerical results are in good agreement with
those obtained by others using more traditional methods. 相似文献
45.
M. Mohandesi Namin A. A. Bidokhti A. Karami Khaniki I. Hasan Zadeh M. Torabi Azad 《Marine Geodesy》2016,39(2):141-164
Complex process of turbulent mixing in Persian Gulf that is a semi-closed sea makes it a good media to test the performance of different turbulence schemes. In this research, we used the 3D ocean model COHERENS (COupled Hydrodynamical Ecological model for REgioNal Shelf seas) for the Persian Gulf with the open boundary in the Hormuz Strait. Of the turbulence schemes for the vertical diffusion available in the COHERENS, we tested four models to investigate the hydrodynamic characteristics of the Persian Gulf. The results show that all of the schemes presented the sea surface salinity (SSS) distribution rather accurately but the k-l and flow-dependent models results have better agreements with observations. The most noticeable difference between the results of four schemes is the differences found in the simulation of turbulent parameters. The turbulent closure schemes generally provide better results, but the algebraic schemes show turbulent parameters far from reality and they do not show substantial changes with time. Generally, the vertical structures of turbulence in the water basins and parameterization of turbulence in water column is very sensitive to the selection of the type of the turbulence scheme. However, large-scale structures that take place within the inflow and outflow area are approximately quasi-horizontal, and the vertical small-scale turbulence does not affect them as much. As a result, they show less sensitivity to the performance of various turbulence schemes. 相似文献
46.
Assessing the groundwater recharge potential zone and differentiation of the spring catchment area are extremely important to effective management of groundwater systems and protection of water quality. The study area is located in the Saldoran karstic region, western Iran. It is characterized by a high rate of precipitation and recharge via highly permeable fractured karstic formations. Pire-Ghar, Sarabe-Babaheydar and Baghe-rostam are three major karstic springs which drain the Saldoran anticline. The mean discharge rate and electrical conductivity values for these springs were 3, 1.9 and 0.98 m3/s, and 475, 438 and 347 μS/cm, respectively. Geology, hydrogeology and geographical information system (GIS) methods were used to define the catchment areas of the major karstic springs and to map recharge zones in the Saldoran anticline. Seven major influencing factors on groundwater recharge rates (lithology, slope value and aspect, drainage, precipitation, fracture density and karstic domains) were integrated using GIS. Geology maps and field verification were used to determine the weights of factors. The final map was produced to reveal major zones of recharge potential. More than 80 % of the study area is terrain that has a recharge rate of 55–70 % (average 63 %). Evaluating the water budget of Saldoran Mountain showed that the total volume of karst water emerging from the Saldoran karst springs is equal to the total annual recharge on the anticline. Therefore, based on the geological and hydrogeological investigations, the catchment area of the mentioned karst springs includes the whole Saldoran anticline. 相似文献
47.
Davood Manzoori Davood Mohammadzadeh Jassur Mir Hojat Kermani 《Astrophysics and Space Science》2006,302(1-4):145-151
New UBV photometry of Algol type binary star U Sge obtained during 1993 are presented, analyzed, and discussed. Wilson-Devinney
code was employed to analyze the light curves. Absolute dimensions of the system were obtained, and positions of both components
on H-R diagram were specified. Finally through color curve analysis absolute visual magnitudes were determined. 相似文献
48.
Using measured radial velocity data of nine double lined spectroscopic binary systems NSV 223, AB And, V2082 Cyg, HS Her, V918 Her, BV Dra, BW Dra, V2357 Oph, and YZ Cas, we find corresponding orbital and spectroscopic elements via the method introduced by Karami and Mohebi (Chin. J. Astron. Astrophys. 7:558, 2007a) and Karami and Teimoorinia (Astrophys. Space Sci. 311:435, 2007). Our numerical results are in good agreement with those obtained by others using more traditional methods. 相似文献
49.
T. Karami S. Elyasi T. Amani 《International Journal of Environmental Science and Technology》2018,15(11):2389-2398
The present work reports treatment of synthetic phenolic wastewater by electrocoagulation process. Aluminum flat sheets were utilized as electrodes. Central composite design combined with response surface methodology has been applied for optimizing the process parameters. The interaction effects of phenol concentration, electrode distance, pH, voltage, and electrolysis time (ET) were analyzed and correlated to assess the efficiency of phenol removal as process response. The ANOVA outcomes declared that the initial phenol concentration (relevant coefficient = ?3.44) and ET (relevant coefficient = 1.42), respectively, are the most and the least effective parameters on the efficiency of phenol removal. Furthermore, optimal factors were obtained as follows: influent phenol concentration = 14.23 mg/L, electrode distance = 2.20 cm, pH = 6.37, voltage = 16.46 V, and electrolysis time = 44.66 min, in which the percentage of phenol removal at this condition was about 90.6%. 相似文献