نتایج جستجو برای: دوربین ماهواره leo

تعداد نتایج: 12683  

Journal: :Pakistan journal of pharmaceutical sciences 2009
Haitham N Qaralleh Muayad M Abboud Khaled M Khleifat Khaled A Tarawneh Osama Y Althunibat

This study was carried out to evaluate the antibacterial activity of aqueous and organic extracts of Thymus capitatus L. (Lamiaceae) leaves and stems. Dried ground powder leaves and stems were extracted with water (aqueous extracts), ethanol, dichloromethane and hexane (Soxhlet extracts). The antibacterial activity of these extracts was evaluated against bacteria using disc diffusion method. Th...

Journal: :Int. J. Satellite Communications Networking 2001
Young Hoon Kwon Dan Keun Sung

In the near future low earth orbit (LEO) satellite communication networks will partially substitute for fixed terrestrial multimedia networks especially in sparsely populated areas. Unlike fixed terrestrial networks, ongoing calls may be dropped if satellite channels are shadowed. Therefore, in most LEO satellite communication networks more than one satellite need to be simultaneously visible i...

2000
X. Zhang R. R. Li P. D. Dapkus D. H. Rich

A sparse nucleation process on sapphire ~0001! substrates has been developed for the growth of GaN thin films. The density of nucleation sites is reduced to only 4310 cm. Based on this process, we performed direct lateral epitaxial overgrowth ~LEO! of GaN by metalorganic chemical vapor deposition on patterned SiO2/sapphire ~0001! substrates. An aggregate lateral to vertical growth rate ratio of...

2007
SANGMO TONY SOHN WILLIAM E. KUNKEL KATHRYN V. JOHNSTON RICHARD J. PATTERSON MICHAEL H. SIEGEL MICHAEL C. COOPER

We present a wide-field (4.5 deg2) photometric and spectroscopic survey of the Leo I dwarf spheroidal (dSph) galaxy to explore its extended morphology and dynamics. As in previous papers in this series, we take advantage of photometry in the M, T2, and DDO51 filter system to select Leo I red giant branch star candidates, and, so far, this selection technique has proven 100% reliable in selectin...

Journal: :Electronics 2022

With the rise of a new generation low Earth orbit (LEO) satellite constellations and advancement 6G network, satellite–terrestrial integrated Internet Things (IoT) in future will achieve global coverage through integration LEO constellation, extend computing to edge network deployment services constellation so as meet demand mass connection latency data processing. The be an cloud combining com...

ژورنال: صوت و ارتعاش 2013

در این مقاله فرایند انجام آزمون‌های ارتعاشات روبش سینوسی و اتفاقی روی مدل سازه‌ای[i] طرح اولیة نانوماهوارة رصد 1، مبتنی بر استاندارد آزمون‌های ارتعاشی آژانس فضایی اروپا[ii] در فاز کیفیت‌سنجی سازه تشریح و ارزیابی شده است. براساس این استاندارد، آزمون‌های روبش سینوسی و اتفاقی در سه راستای عمود بر هم، که یکی از آنها باید در امتداد پیشرانش موشک ماهواره‌بر باشد، انجام شده است. میزان تراز و مدت زمان ا...

ژورنال: فیزیک زمین و فضا 2011

مسئله تعیین مدار دینامیکی یک ماهواره چیزی جز حل یک معادله دیفرانسیل مرتبه دو نیست که امروزه این معادله به علت دقت زیاد روش‌های عددی، به‌صورت عددی حل می‌شود. علی‌رغم پیشرفت رایانه‌ها و فنون محاسباتی، انتگرال‌گیری مدار همچنان از فرایندهای زمان‌بر در ژئودزی ماهواره‌ای به حساب می‌آید. علت این مسئله لزوم محاسبه شتاب به صورت نقطه‌‌به‌‌نقطه است. اگرچه می‌توان با استفاده از فنون برداری‌‌سازی (Vectorize...

1999
Benjamin J. Taylor

Castro et al. (1996) have concluded that μ Leo has three times the solar metallicity. That conclusion is based on their own work and on rezeroed values of [Fe/H] from the literature. A review of their paper reveals that there are significant omissions from their list of literature results. In addition, their procedure for establishing zero points for values of [Fe/H] is found to be fallacious. ...

2001
P. Loreti M. Luglio R. Kapoor J. Stepanek M. Gerla F. Vatalaro M. A. Vazquez-Castro

Low Earth Orbit (LEO) satellites are an essential complement of the cellular radio infrastructure, especially the Universal Mobile Telecommunications System (UMTS), for mobile (pedestrian and, more important, vehicular) access to the Internet in sparsely populated areas, where high bandwidth UMTS cells cannot be economically deployed. LEO users would eventually switch between the satellite segm...

Journal: :Computer Networks 2007
Evangelos Papapetrou Stylianos Karapantazis Fotini-Niovi Pavlidou

Notwithstanding the limited commercial success of the first narrowband Low Earth Orbit (LEO) satellite systems, the interest of the scientific community in this type of systems has been revived on the basis of the current trend toward the migration to all IP-based services. LEO systems can play a pivotal role in providing services to areas where there is no substantial terrestrial infrastructur...

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