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521.
Hamid M. K. Al-Naimiy Huda A. Al-Mahdi Aasem O. Al-Sikab Ali A. Mutter 《Astrophysics and Space Science》1985,117(2):351-361
The aim of the present paper is to present the analysis of light changes of four Lyrae eclipsing systems (DO Cas, KR Cyg, V388 Cyg, and SV Cen) using the automated Fourier techniques in the frequency-domain.The applicability of the above method to the Lyrae system discussed. New physical and geometrical elements of these systems are derived. Their positions in the H-R diagram and mass-luminosity diagram are indicated. 相似文献
522.
S. Hamid Mehdipour 《Astrophysics and Space Science》2013,345(2):339-344
We study some features of entropic force approach in the presence of a noncommutative Schwarzschild-deSitter black hole. In this setup, there exists a similarity between the small and large scales. There are two finite cut-off in very short and long distances wherein the force and energy graph stop abruptly at those scales. We find that the existence of a deSitter core around the origin, induced by noncommutativity, in addition to a standard deSitter background at large scale may lead to a violation of the equivalence principle. Finally in order to directly observe the finite cut-off at short-scale gravity, caused by noncommutativity quantum fluctuations, we derive an effective gravitational constant. 相似文献
523.
China Ocean Engineering - The breakwaters have experienced many changes during their construction history. These changes have been considered to improve their performance, depending on their... 相似文献
524.
Hamid Gadouri Khelifa Harichane Mohamed Ghrici 《Marine Georesources & Geotechnology》2013,31(9):1130-1148
AbstractAn experimental investigation was undertaken in order to assess the effect of sodium (Na2SO4) and calcium (CaSO4·2H2O) sulphates and curing period on stress–strain curves and failure modes of grey (GS) and red (RS) clayey soils stabilised by lime (L), natural pozzolana (NP) and their combinations (L–NP). Several soil–L–NP mixtures were studied to be used as subgrade soils for road pavements. Stress–strain curves were obtained from unconfined compressive strength (UCS) test made on several soil–L–NP specimens after curing for 7 and 120 days. Tests results showed that the use of L or L–NP without sulphates produced a significant increase in peaks stress of both clayey soils and then modified their stress–strain curves from nonlinear to linear behaviour almost up to 70% of peak stress after a longer curing period. However, the presence of 2% Na2SO4 or any CaSO4·2H2O content provided beneficial effects on peaks stress and stress–strain curves of both stabilised clayey soils and then improved their linearity almost up to 95% of peak stress after curing for 120 days. In contrast, the presence of 6% Na2SO4 caused undesirable effects. In addition, both sulphates greatly affected the failure modes of soil–L–NP specimens, particularly at a later stage. 相似文献
525.
Propagation of ion acoustic waves in plasmas containing electrons, positrons and high relativistic ions is investigated. It
is shown that the Korteweg-de Vries (KdV) equation describes the nonlinear waves in this media. The amplitude and energy of
the KdV solitary waves are derived and the effects of relativistic ions on these quantities are discussed. 相似文献
526.
Hamid Reza Pakzad 《Astrophysics and Space Science》2011,332(2):269-277
In this paper, the ion-acoustic solitons in a weakly relativistic electron-positron-ion plasma have been investigated. Relativistic
ions, Maxwell-Boltzmann distributed positrons and nonthermal electrons are considered in collisionless warm plasma. Using
a reductive perturbation theory, a Korteweg-de Vries (KdV) equation is derived, and the relativistic effect on the solitons
is studied. It is found that the amplitude of solitary waves of the KdV equation diverges at the critical values of plasma
parameters. Finally, in this situation, the solitons of a modified KdV (mKdV) equation with finite amplitude is derived. 相似文献
527.
Hamid Reza Pakzad 《Astrophysics and Space Science》2011,333(1):247-255
Ion acoustic shock waves (IASWs) are studied in a plasma consisting of electrons, positrons and ions. Boltzmann distributed
positrons and superthermal electrons are considered in the plasma. The dissipation is taken into account the kinematic viscosity
among the plasma constituents. The Korteweg–de Vries–Burgers (KdV–Burgers) equation is derived by reductive perturbation method.
Shock waves are solutions of KdV–Burgers equation. It is observed that an increasing positron concentration decreases the
amplitude of the waves. Furthermore, in the existence of the kinematic viscosity among the plasma, the shock wave structure
appears. The effects of ion kinematic viscosity (η
0) and the superthermal parameter (k) on the ion acoustic waves are found. 相似文献
528.
The metamorphic rocks of the Aligudarz-Khonsar region can be divided into nine groups: slate, phyllite, sericite schist, biotite-muscovite schist, garnet schist, garnet-staurolite schist, staurolite schist, mylonitic granite, and marble. In this metamorphic region, four phases of metamorphism can be identified (dynamothermal, thermal, dynamic and retrograde metamorphism) and there are three deformation phases (D1, D2 and D3). Paleozoic pelagic shales experienced prograde metamorphism and polymetamorphism from the greenschist to amphibolite facies along the kyanite geotherm. The metapelites show prograde dynamothermal metamorphism from the greenschist to amphibolite facies. Maximum degree of dynamothermal metamorphism is seen in the Nughan bridge area. Also development of the mylonitic granites in the Nughan bridge area shows that dynamic metamorphism in this area was more intense than in other parts of the AligudarzKhonsar metapelitic zone. The chemical zoning of garnets shows three stages of growth and syn-tectonic formation. With ongoing metamorphism, staurolite appeared, and the rocks reached amphibolite facies, but the degree of metamorphism did not increase past the kyanite zone. Thus, metamorphism of the pelitic sediments occurred at the greenschist to amphibolite facies (kyanite zone). Thermodynamic studies of these rocks indicate that the metapelites in the Aligudarz-Khonsar region formed at 490–550°C and 0.47–5.6 kbar. 相似文献
529.
Al-Qadami Ebrahim Hamid Hussein Mustaffa Zahiraniza Shah Syed Muzzamil Hussain Matínez-Gomariz Eduardo Yusof Khamaruzaman Wan 《Natural Hazards》2022,110(1):325-348
Natural Hazards - Vehicles can be easily swept away by floodwaters once the flow velocity and depth reach certain critical limits, with probabilities toward fatality reported to be nearly 50%.... 相似文献