نتایج جستجو برای: variable gravity field the time

تعداد نتایج: 16343661  

Journal: :فیزیک زمین و فضا 0
مهروز خادمی کارشناس ارشد ژئودزی، گروه مهندسی نقشه برداری، دانشکده نقشه برداری، دانشگاه صنعتی خواجه نصیرالدین طوسی، تهران، ایران مهدی نجفی علمداری دانشیار، گروه مهندسی نقشه برداری، دانشکده نقشه برداری، دانشگاه صنعتی خواجه نصیرالدین طوسی، تهران، ایران محمدعلی شریفی استادیار، گروه مهندسی نقشه برداری، پردیس دانشکده های فنی، دانشگاه تهران، ایران

the recent dedicated satellite gravimetry missions have provided huge amount of high quality gravity data with global coverage. from computational point of view, estimation of the unknown gravity field parameters is a highly demanding task due to the sheer number of observations and the unknown coefficients. different computational schemes have been proposed to tackle the problem. since the ear...

Journal: :فیزیک زمین و فضا 0
عباسعلی علی اکبری بیدختی استاد، گروه فیزیک فضا، مؤسسة ژئوفیزیک دانشگاه تهران سرمد قادر دانشیار، گروه فیزیک فضا، مؤسسة ژئوفیزیک دانشگاه تهران معصومه شاهسواری دانش آموخته کارشناسی ارشد، گروه فیزیک فضا، مؤسسة ژئوفیزیک دانشگاه تهران

geophysical fluids such as atmosphere and ocean often have stable density stratification; hence internal gravity waves are generated and propagated through them which are important in momentum and energy transfer in these media. these waves are also believed to generate layered structures in such media. recently there have been numerous theoretical, experimental and numerical studies on the way...

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

in this investigation the effect of external field on the electron density of nanostructures of cds, cdse, cdte, gaas and polymeric structure of three, four, five and six units of cds as a kind of nanosolar cells has been studied theoretically. as modeling this system in nanodimension, molecular structures has used. specific properties of molecular structures permit us to consider different sym...

پایان نامه :وزارت علوم، تحقیقات و فناوری - دانشگاه تربیت مدرس - دانشکده مهندسی صنایع 1387

according to webster and wind (1972) and anderson et al (1987), “organizational buying is a complex process and involves many people from different functional areas, multiple goals and potentially conflicting decision criteria. moreover, the customers of today are also more knowledgeable and selective when making their purchasing decisions. since a key to organizational survival is the retentio...

Journal: :فیزیک زمین و فضا 0
عبدالرحیم عسکری استادیار، دانشگاه تربیت معلم سبزوار وحید ابراهیم زاده اردستانی دانشیار، گروه فیزیک زمین، مؤسسة ژئوفیزیک دانشگاه تهران و قطب علمی مهندسی نقشه برداری و مقابله با سوانح طبیعی علیرضا آزموده اردلان استاد، گروه مهندسی نقشه برداری، قطب علمی مهندسی نقشه برداری در مقابله با سوانح طبیعی، پردیس دانشکده های فنی

measuring field gravity in sea due to the accelerations introduced via waves and movements to the gravity measuring systems has a low accuracy since according to einstein's equalent principle, gravimeter isn't able to separate the gravity acceleration from another acceleration. ship borne gravimetery observations by means of like oscillations and accelerations of the ship motion, and ...

پایان نامه :وزارت علوم، تحقیقات و فناوری - دانشگاه اصفهان 1389

implicit and unobserved errors and vulnerabilities issues usually arise in cryptographic protocols and especially in authentication protocols. this may enable an attacker to make serious damages to the desired system, such as having the access to or changing secret documents, interfering in bank transactions, having access to users’ accounts, or may be having the control all over the syste...

پایان نامه :وزارت علوم، تحقیقات و فناوری - دانشگاه تربیت مدرس - پژوهشکده مهندسی فرایند 1395

abstract: mineral scaling in oil and gas production equipment is one of the most important problem that occurs while water injection and it has been recognized to be a major operational problem. the incompatibility between injected and formation waters may result in inorganic scale precipitation in the equipment and reservoir and then reduction of oil production rate and water injection rate. ...

R Kakar, S Kakar

The propagation of torsional waves in a prestressed fiber-reinforced half-space under the effect of magnetic field and gravity has been discussed. The problem has been solved analytically using Whittaker function to obtain the exact solution frequency equations. Numerical results for stress, gravity and magnetic field are given and illustrated graphically. Comparisons are made with the results ...

پایان نامه :دانشگاه تربیت معلم - تهران - دانشکده علوم انسانی 1390

this study investigated the effects of manipulating the cognitive complexity of tasks along +/- few elements and the time limits on l2 learners writing performance. to conduct the study, 60 iranian efl learners with two levels of proficiency, low and high intermediate, were selected and assigned to three groups based on the time devoted to task completion. the participants performed both a simp...

پایان نامه :وزارت علوم، تحقیقات و فناوری - دانشگاه فردوسی مشهد 1388

abstract following innovations in the field of elt, a new topic which has recently attracted a lot of attention is metaphor analysis. although this area of research is still in its infancy in elt, it seems that the idea can shed more light on the puzzle of english language learning and teaching. therefore, the major aim of this study is to analyze language learning and teaching in formal a...

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