نتایج جستجو برای: solar activity

تعداد نتایج: 1247681  

M. Malekshahi Byranvand

Dye-sensitized solar cells present promising low-cost alternatives to the conventional Silicon (Si)-based solar cells. The counter electrode  generally consists of Pt deposited onto FTO plate. Since Pt is rare and expensive metal, nanostructured carbonaceous materials have been widely investigated as a promising alternative to replace it. Carbon nanotubes  have shown significant properties such...

Journal: :Symposium - International Astronomical Union 1997

Journal: :مدیریت مخاطرات محیطی 0
فریده سبزه ای کارشناس ارشد ژئودزی - هیدروگرافی گروه مهندسی نقشه برداری، پردیس دانشکده های فنی دانشگاه تهران، ایران محمدعلی شریفی دانشیار، گروه مهندسی نقشه برداری و پژوهشکده مهندسی فناوری های اطلاعات مکانی، پردیس دانشکده های فنی دانشگاه تهران، ایران مهدی آخوندزاده استادیار، گروه مهندسی نقشه برداری، پردیس دانشکده های فنی دانشگاه تهران، ایران

earthquakes show unknown nonlinear behavior and given the magnitude of the earthquake, we would encounter certain changes in lithosphere, atmosphere and ionosphere. the ionospheric parameters have been found to be sorely susceptible to major earthquakes. in addition to the ionospheric variations generated by solar activity, there are remarkable temporary changes in the ionosphere that are gener...

1997
K. Mursula I. Usoskin B. Zieger

Recently, Djurovic and Pâquet (1996) claimed to have found an oscillation with a period of about 5.5 years in several solar and solar-terrestrial parameters, in particular in solar activity as indicated by sunspot numbers. Since the temporal evolution of solar activity and solar-terrestrial environment is of great interest in many fields, we have examined their claim in detail. We show here tha...

2015
Scott W. McIntosh Robert J. Leamon

The Sun provides the energy necessary to sustain our existence. While the Sun provides for us, it is also capable of taking away. The weather and climatic scales of solar evolution and the Sun-Earth connection are not wellunderstood. There has been tremendous progress in the century since the discovery of solar magnetism—magnetism that ultimately drives the electromagnetic, particulate, and eru...

2002
Sarbani Basu

Solar oscillations frequencies show a distinct change with solar activity. The changes in frequencies can be used to study the time variation of solar structure. We discuss constraints on the changes in solar structure with time as obtained with helioseismic data covering the last six years. The frequency variations appear to be dominated by changes in the nearsurface layers rather than by chan...

1999
K. J. Li

In this paper, 20 solar-activity phenomena are collected to investigate solar activity in solar cycle 21. The results obtained show that we can hardly say that either the south dominance of solar activity or the north dominance exists for solar cycle 21. It is also inferred in this paper that solar activity in solar cycle 21 has a northern bias at first, then as the cycle progresses, southern p...

1997
P. V. S. Rama Rao P. T. Jayachandran P. Sri Ram B. V. Ramana Rao D. S. V. V. D. Prasad K. K. Bose

The characteristics of VHF radiowave scintillations at 244 MHz (FLEETSAT) during a complete solar cycle (1983±93) at a low-latitude station, Waltair (17.7°N, 83.3°E), are presented. The occurrence of night-time scintillations shows equinoctial maxima and summer minima in all the epochs of solar activity, and follows the solar activity. The daytime scintillation occurrence is negatively correlat...

Journal: :Physical review. E, Statistical, nonlinear, and soft matter physics 2004
Nicola Scafetta Paolo Grigolini Timothy Imholt Jim Roberts Bruce J West

This paper presents a study of the influence of solar activity on the earth's temperature. In particular, we focus on the repercussion of the fluctuations of the solar irradiance on the temperature of the Northern and Southern hemispheres as well as on land and ocean regions. While solar irradiance data are not directly analyzed, we make use of a published solar irradiance reconstruction for lo...

2017
Gustavo A. Mansilla

Method: For this purpose, foF2 data from four Antarctic stations were analyzed during three intense magnetic storms occurred in high solar activity (years 2002 and 2003). In general, negative storm effects irrespective of the local time were observed during the first part of the storms (main phase). Negative effects were also observed more often than positive effects during the first part of th...

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