نتایج جستجو برای: samples with high frequency in magnetic susceptibility (increasing or decreasing) were selected for other studies of magnetic parameters. results and discussionthe variation of magnetic susceptibility signal in the nowdeh section suggests variation in climate conditions and mechanisms during the late quaternary. the magnetic susceptibility relationship with loess/paleosol deposits resulted in low magnetic susceptibility values in cold and dry climate periods (loess) and high magnetic susceptibility values in warm and humid climate periods (paleosoil). therefore

تعداد نتایج: 27599190  

پایان نامه :وزارت علوم، تحقیقات و فناوری - دانشگاه صنعتی اصفهان - دانشکده فیزیک 1390

in this thesis, barium ferrite nano particles were prepared by sol-gel method. their structural and magnetic properties of samples have been investigated using thermo gravimetric analysis (tg-dta), x-ray powder diffractometer (xrd), fourier transform infrared (ftir), scanning electron microscopy (sem), field emission scanning electron microscopy (fesem), ac susceptometer, vibrating sample magne...

Journal: :پژوهش های جغرافیای طبیعی 0
وحید فیضی دانشجوی دکتری جغرافیا، اقلیم شناسی، دانشگاه تهران حبیب علیمحمدیان استادیار گروه زمین شناسی (گرایش محیط مغناطیس)، سازمان زمین شناسی و اکتشافات معدنی کشور قاسم عزیزی دانشیار، گروه جغرافیای طبیعی، اقلیم شناسی، دانشگاه تهران حسین محمدی استاد، گروه جغرافیای طبیعی، اقلیم شناسی، دانشگاه تهران علی اکبر شمسی پور استادیار، گروه جغرافیای طبیعی، اقلیم شناسی، دانشگاه تهران

introduction in general, loess sediments are one of the most widespread forms of aeolian sediments. during the past few decades, loess stratigraphy studies played key role in the investigation about global climate changes. these sediments are usually yellowish in color and silt makes 70 to 90 percent of its volume. in iran, loesses outcrop are often in northeast part of south caspian sea. the p...

پایان نامه :وزارت علوم، تحقیقات و فناوری - دانشگاه رازی - پژوهشکده فنی و مهندسی 1388

asymmetric polyethersulfone (pes) microfiltration flat sheet membranes were composed by the phase inversion method (pim) and were used as supports. composite membranes were fabricated by coating silicone rubber as selective layer. effect of different concentrations of pes and pdms and different solvent such as nmp, dmf and dms effects as pes solvents and support thickness and different coagulat...

Journal: :پژوهش های جغرافیای طبیعی 0
وحید فیضی دانشجوی دکتری جغرافیا، اقلیم شناسی، دانشگاه تهران حبیب علیمحمدیان استادیار گروه زمین شناسی (گرایش محیط مغناطیس)، سازمان زمین شناسی و اکتشافات معدنی کشور قاسم عزیزی دانشیار، گروه جغرافیای طبیعی، اقلیم شناسی، دانشگاه تهران حسین محمدی استاد، گروه جغرافیای طبیعی، اقلیم شناسی، دانشگاه تهران علی اکبر شمسی پور استادیار، گروه جغرافیای طبیعی، اقلیم شناسی، دانشگاه تهران

expanded abstract introduction in general, loess sediments are one of the most widespread forms of eolian sediments. during the past few decades, loess stratigraphy studies played key role in global climate changes. these sediments are usually yellowish in color and silt makes 70 to 90 percent of it volume. in iran, loesses outcrop often in northeast of south caspian sea. the previous studies r...

پایان نامه :وزارت علوم، تحقیقات و فناوری - دانشگاه گیلان - دانشکده فنی و مهندسی 1390

magnetic resonance imaging (mri) is a notable medical imaging technique that makes of phenomenon of nuclear magnetic resonance. because of the resolution and the technology being harmless, mri has considered as the most desirable imaging technique in clinical applications. the visual quality of mri plays an important role in accuracy of medical delineations that can be seriously degraded by exi...

پایان نامه :وزارت علوم، تحقیقات و فناوری - دانشگاه شهید چمران اهواز - دانشکده مهندسی علوم آب 1393

drought is transient phenomenon , slow , repetitive and integral part of the climate of each region. drought begins with a substantial reduction in precipitation over the long-term average rainfall and over time, reduced soil moisture and surface and ground water resources will continue to decrease. this phenomenon is the most important in bakhtegan basin because of its importance in strategic ...

پایان نامه :وزارت علوم، تحقیقات و فناوری - دانشگاه رازی - دانشکده علوم 1392

a novel acrylic acid-functionalized fe3o4 magnetic nanoparticle with a core-shell structure was developed for utilization as a heterogeneous organosuperacid in chemical transformations. the structural, surface, and magnetic characteristics of the nanosized catalyst were investigated by various techniques such as transmission electron microscopy (tem), thermogravimetric analysis (tga), and ft-ir...

پایان نامه :وزارت علوم، تحقیقات و فناوری - دانشگاه ارومیه - دانشکده علوم 1391

nanotechnology is a general term which is related with field of all advanced science term that generally predicates with all modern technologies which consider nanoscales. improvement in the quality of products by adding some nanoparticles and study of their behavior in the presence of these nanoparticles have been obtained in many researches. on the other hand numerous demands for sowing ...

پایان نامه :وزارت علوم، تحقیقات و فناوری - دانشگاه گیلان - دانشکده فنی و مهندسی 1390

sange siyah dam is located two kilometers down the kabod khani village. the environ of ghorrve city in kurdestan province. this is an clay core dam. in this dam instrumentation is performed in three section and consist of electrical piezometers, total pressure cells, settlement cells and so on. the main objective of instrumentation is to control the behavior of dam body and foundation, end else...

پایان نامه :وزارت علوم، تحقیقات و فناوری - دانشگاه شیراز - دانشکده علوم 1392

gol-e-gohar iron ore mine of sirjan in southern part of iran is a large open pit that operates below the groundwater table and during mining operation, dewatering is required to prevent operation processes from flooding. current operation is going on by digging wells in or out of the pit and pumping to prevent flooding. as a result of the former dewatering operation a vast deep cone of depressi...

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