نتایج جستجو برای: Oscillation

تعداد نتایج: 38534  

Journal: :پژوهش های جغرافیایی (منتشر نمی‏شود) 0
داریوش یاراحمدی استادیار گروه جغرافیا، دانشگاه لرستان قاسم عزیزی دانشیار دانشکده جغرافیا-دانشگاه تهران

in this article the relationship between the amount of seasonal rainfall (autumn, winter and spring) and climate indices in iran have been studied. the climate indices (the southern oscillation(soi),the north atlantic oscillation(nao), arctic oscillation(ao),nino 3/4,the multivariate enso index(mei),trans_ nino index(tni) and the pacific decadal oscillation(pdo) are used as independent variable...

Journal: :مهندسی بیوسیستم ایران 0
علی رضایی دانشجوی کارشناسی ارشد گروه مهندسی مکانیک بیوسیستم دانشگاه شیرازاز محمد لغوی استاد گروه مکانیک بیوسیستم دانشگاه شیراز سعادت کامگار استادیار گروه مکانیک بیوسیستم دانشگاه شیراز داریوش زارع دانشیار گروه مکانیک بیوسیستم دانشگاه شیراز

a portable and light pneumatic branch shake system was designed and manufactured in this research for harvesting fruits that can be harvested by shaking branch. required air flow and electric current are provided for operating system from category containing electrical generator and air compressor on wheelbarrows and portable chassis. vibration is equipped by programmable logic controller (plc)...

Journal: :جغرافیا و مخاطرات محیطی 0
مجید رضائی بنفشه محمد سعید نجفی حبیبه نقی زاده شعیب آب خرابات

introduction long-term annual extreme climate events, especially temperature and precipitation, have generally been used as indicators for the assessment of climate change. one of the most changeable climatic variables in time and space is precipitation. there are great number of research papers focusing on extreme precipitation on global, regional and national scales have been written. the res...

بحرینی نژاد, طیبه, عابدینی, عباس,

In this paper, the effect of compressive viscosity on the slow mode oscillation of solar corona loops is studied. The coronal loops medium are considered in low beta condition, uniform magnetic field in the presence of gravitational stratification and temperature gradient. Two-dimensional Magneto-Hydro-Dynamics (MHD) equations are perturbed about the equilibrium and thenthese equations are lin...

امیرحسینی, طاهره, عابدینی, عباس,

Slow magneto-acoustic waves are often observed in polar plumes and active region fan loops. The observed periodicities of these waves are in the range of 1- 40 minutes. Mainly, the ratio of damping time to the oscillation period is less than 2 (equal to the ratio damping length to the wave length), which corresponds to the strong damping regime. In general, slow magneto-acoustic waves can be da...

The purpose of this study was to investigate the effects of the North Atlantic Oscillation on the middle levels of Atmosphere and precipitation changes in the West of country. To do this, first monthly rainfall data of 17 synoptic stations of the West Country in period of 30 years from 1984 to 2014 of country were collected from Meteorological Organization. As well as North Atlantic Oscillation...

Journal: :physical chemistry and electrochemistry 0
hossein jalali jahromi department of chemistry, mahshahr branch, islamic azad university, mahshahr, iran

the reaction of ch3o2 radicals with acetaldehyde on the solid surface of nh4no3 has been studied in a flow capillary reactor at low pressure and room temperature. the experiments were performed using epr spectrometer combined with the kinetic method of radicals freezing. peroxy radicals revealed an oscillation complex behavior during the process regarding to the phenomenon of radicals multiplic...

The objective of this paper is to examine the effectiveness of wall oscillation as a control scheme of drag reduction. Two flow configurations are considered: constant flow rate and constant mean pressure gradient. The Navier-Stokes equations are solved using Fourier-Chebyshev spectral methods and the oscillation in sinusoidal form is enforced on the walls through boundary conditions for the sp...

A. Meghdari, G. Vosoughi and A. Sekhavat,

– One of the important applications of robots is in material handling and transport of various shaped objects. In cases where an object cannot be directly grasped by the robot gripper, and must be carried by a hook, it may be subject to undesirable swings during transport. This paper presents an analytical method for minimizing the oscillation of a suspended object during transport. This method...

A coronal loop can be oscillated in various directions. A basic type of coronal loop oscillation is called transverse oscillation that can be caused by different factors, such as nearby active regions and flares. The damping of transverse oscillation may be produced by the dissipation mechanism or the wake of the traveling disturbance. The aim of this paper is to estimate the damping time of tr...

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