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Author(s): 

DEMYANOVICH Y.K.

Issue Info: 
  • Year: 

    2008
  • Volume: 

    222
  • Issue: 

    2
  • Pages: 

    23-43
Measures: 
  • Citations: 

    1
  • Views: 

    111
  • Downloads: 

    0
Keywords: 
Abstract: 

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Issue Info: 
  • Year: 

    2014
  • Volume: 

    3
  • Issue: 

    2
  • Pages: 

    71-80
Measures: 
  • Citations: 

    0
  • Views: 

    351
  • Downloads: 

    130
Abstract: 

A new wideband Wilkinson Power Divider which use the nonuniform substrate integrated waveguide (NSIW) method is presented in this paper. This structure utilizes NSIWs instead of the uniform quarter wavelength SIWs in conventional Wilkinson power divider. The proposed structure is analyzed by odd and even mode analysis. The proper NSIW section widths can be extracted by using even mode while the divider resistances are achieved by odd mode analysis. Moreover using of half mode structure in the NSIW and two output ports reduces the overall size of the proposed divider. Finally a wideband Wilkinson power divider is designed and simulated to verify the proposed design method. A good return loss (S11, S22) and insertion loss (S21) across a very wideband width from 10 GHz to 20 GHz is achieved. Also, the isolation (S23) is better than -10 dB from 9.5 GHz to 21.5 GHz for the designed NSIW divider.

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Issue Info: 
  • Year: 

    2009
  • Volume: 

    35
  • Issue: 

    2 (SECTION: GEOLOGY)
  • Pages: 

    21-26
Measures: 
  • Citations: 

    0
  • Views: 

    1190
  • Downloads: 

    0
Abstract: 

The objective of exploration seismology is to measure accurately reflected wavefields from subsurface interfaces in order to generate an image of the geological formations. More often the seismic data is non-uniformly sampled, i.e. the data is not acquired on an equidistantly spaced grid. This may result in artifacts during data processing that complicate interpretation. Sampling may be nonuniform because of human-related reasons such as: 1. Faulty equipment and positioning errors, 2. It may be due to environmental circumstances, such as cable feathering in marine acquisition induced by ocean currents or 3. Due to inaccessible areas in land acquisition (cities, rivers, and canyons).The generation of uniformly sampled data from nonuniformly sampled data is called reconstruction and many different methods to reconstruct seismic data have been published over the years. The method used in this paper is called reconstruction of nonuniformly sampled data with least squares Fourier transform. It is based on estimating the Fourier coefficients that describe the non-uniformly sampled data, and once these coefficients have been found the signal can be reconstructed on any suitable grid via an inverse Fourier transformation. The efficiency of the method is evaluated on both real and synthetic seismic. All necessary codes were written in MATLAB environment.

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Journal: 

Issue Info: 
  • End Date: 

    آبان 1378
Measures: 
  • Citations: 

    6
  • Views: 

    256
  • Downloads: 

    0
Keywords: 
Abstract: 

در این طرح یک سیستم برق غیرقابل قطع که بصورت ON- LINE عمل می نماید طراحی و به صورت نیمه صنعتی ساخته شد. طراحی با اصول استانداردهای مورد نیاز برای مراکز صنعتی صورت گرفته به نحوی که قابلیت بکارگیری در این مراکز را داشته باشد. در مجموع سیستم شامل یک شارژر با ورودی سه فاز و خروجی 220 VDC به قدرت 15 kW، یک دستگاه اینورتر تکفاز با خروجی 50 Hz/ 220 VAC و قدرت 15 kVA در PF=0.8 و در ابعاد [2100 (H)×2400 (W)×750 (D)] mm آماده گردید.کارکرد دستگاه در دو حالت استاتیک و دینامیک تست گردید و نتایج حاصل مطلوب بوده است. نتایج کارکرد دستگاه مطابق با استاندارد IEC گویای کارکرد مناسب آن می باشد. عملکرد Static Switch و انتقال بار به برق شهر و اینورتر با زمان مطلوب و قابل قبول حاصل گردید و در کلیه حالات انتقال عملکرد مناسب بوده است. در مجموع با توجه به نحوه طراحی و پارامترهای انتخابی و از طرفی انتخاب عناصر مناسب در مدارها و رعایت استانداردهای مورد نیاز دستگاه دارای ضریب اطمینان بالا می باشد و قابلیت بکارگیری در محیطهای صنعتی از جمله صنایع مختلف نفت و برق را داراست.

Yearly Impact:   مرکز اطلاعات علمی Scientific Information Database (SID) - Trusted Source for Research and Academic Resources

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Issue Info: 
  • Year: 

    2017
  • Volume: 

    48
  • Issue: 

    1
  • Pages: 

    1-14
Measures: 
  • Citations: 

    0
  • Views: 

    229
  • Downloads: 

    111
Abstract: 

In recent decades the effects of magnetic and electric fields on living cells and organisms have gained the increasedattention of researchers. In recent years, dielectrophoresis based microfluidics systems have been used to manipulatebiological micro particles, such as red blood cells, white blood cells, platelets, cancer cells, bacteria, yeast, microorganisms, proteins, DNA, etc. So most previous researchers have studied particle trajectory under theapplication of electric field in order to better design of such micro devices. In the current study the effect of nonuniformelectric field on a single cell is investigated. A neutral particle polarizes in the presence of electric field. It causes localchange in electrostatic potential distribution and local nonuniformity in electric field. These changes are ignored inprevious researches and effective dipole moment (EDM) approximation is applied to predict the DEP force exerted oncells. In the present research the effect of cell on electrostatic potential distribution and electric stresses acting on cellsurface is studied. To this end, the cell shape and internal boundary conditions on cell surface must be considered incomputational domain. To do this, Immersed Interface Method (IIM) which is a modified finite difference method isemployed. Some numerical results are presented to show the good accuracy of mentioned numerical method. Theelectric stresses on cell surface are calculated by Maxwell Stress Tensor (MST). Also some results are presented tovalidate the numerical solution and investigate the accuracy of EDM approximation. Other electrokinetic effects suchas electrophoresis and electro-osmosis are neglected in this study.

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Issue Info: 
  • Year: 

    1380
  • Volume: 

    10
Measures: 
  • Views: 

    2104
  • Downloads: 

    0
Abstract: 

یکی از معضلات ثبت سیگنالهای الکتروکاردیوگرام(ECG)  اضافه شدن نویز برق شهر، نویز سرگردانی خط مبنا و سیگنالEMG  به آن است. در این مقاله هدف ارزیابی روشهای مختلف حذف نویز سرگردانی خط مبنا است. این نویز ناشی از آرتیفکتهای تنفسی و حرکتی، جابجایی الکترودها و حرکت آنها روی بدن بیمار است و باعث ایجاد یک سطح شناور روی سیگنالECG  می شود. در اینجا برای حذف این نویز فیلترهای دیجیتال معمولی، فیلترهای وفقی، فیلترهای وفقی سری، فیلترهای وقفی ویولت و روشTSC بررسی و ارزیابی می شوند. نتایج بدست آمده نشان دهنده برتری روشهای وفقی سری و روشTSC نسبت به سایر روشهای به کار رفته است.

Yearly Impact:   مرکز اطلاعات علمی Scientific Information Database (SID) - Trusted Source for Research and Academic Resources

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Issue Info: 
  • Year: 

    2017
  • Volume: 

    15
  • Issue: 

    3
  • Pages: 

    185-193
Measures: 
  • Citations: 

    0
  • Views: 

    3595
  • Downloads: 

    0
Abstract: 

Teleoperation systems have attracted more attention in processes that human operator’s availability is difficult. In this paper, using retarded functions, teleoperation systems have been modeled as a special case of Network Control Systems (NCS) with nonuniform sampling and network delays. It is assumed that slave and master robots are linear and continues-time systems and input-delay approach is used for the stability analysis. Using the proposed Lyapunov function, the sufficient conditions for the stability of discrete network-based teleoperation system is proposed. It will be represented that the proposed conditions are less conservative than previous recent researches. Also an upper bound of sampling time for discrete control signals is computed in a manner that does not disturb the stability conditions. To meet this condition the problem is defined as the convex optimization program and is represented by the LMI terms. In the simulation part, the behavior of the teleoperation system under the nonuniform sampling is represented and the effect of sampling time on the trade-off between the stability and transparency has been studied.

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Issue Info: 
  • Year: 

    2018
  • Volume: 

    8
  • Issue: 

    16
  • Pages: 

    107-114
Measures: 
  • Citations: 

    0
  • Views: 

    768
  • Downloads: 

    0
Abstract: 

In this work, the propagation of the electrostatic drift waves is studied in a non-uniform quantum plasma medium. The analytical expression for dispersion relation of the waves is derived by taking into account the resistivity and quantum aspects of the medium. It has been shown that the quantum effects, alter the dispersion relation of the drift modes. The result is the appearance of modified electron diamagnetic drift waves as well as ion acoustic waves. Furthermore, the velocities of these waves are greater than their classical case. The graphical analysis also revealed that the quantum corrections cause electron branch of the drift waves to become propagative. In the presence of resistivity, the electron drift wave is always unstable, whereas the ion branch of the drift wave becomes damped. On the other hand, in the absence of quantum aspects and given zero resistivity, the two generated ion acoustic and electron drift waves are completely stable.

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Issue Info: 
  • Year: 

    1394
  • Volume: 

    1
Measures: 
  • Views: 

    337
  • Downloads: 

    0
Abstract: 

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Yearly Impact:   مرکز اطلاعات علمی Scientific Information Database (SID) - Trusted Source for Research and Academic Resources

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Author(s): 

Issue Info: 
  • Year: 

    1391
  • Volume: 

    6
  • Issue: 

    3
  • Pages: 

    0-0
Measures: 
  • Citations: 

    0
  • Views: 

    477
  • Downloads: 

    0
Keywords: 
Abstract: 

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