نتایج جستجو برای: power quality
تعداد نتایج: 1209969 فیلتر نتایج به سال:
since its introduction in 1959, translation quality assessment (tqa) has been among the most addressed research topics in translation studies. during recent years, there has been a crucial increase on the study of tqa. various methods have come on scene. although these methods are based on scientific theories, most of them have remained at the level of theory. juliane house’s model is among tho...
در سالهای اخیر،اختلالات کیفیت توان مهمترین موضوع می باشد که محققان زیادی را برای پیدا کردن راه حلی برای حل آن علاقه مند ساخته است.امروزه کیفیت توان در سیستم قدرت برای مراکز صنعتی،تجاری وکاربردهای بیمارستانی مسئله مهمی می باشد.مشکل ولتاژمثل شرایط افت ولتاژواضافه جریان ناشی از اتصال کوتاه مدار یا وقوع خطا در سیستم بیشتر مورد توجه می باشد. برای مطالعه افت ولتاژ واضافه جریان،محققان زیادی کار کرده ...
the study of air infiltration into the buildings is important from several perspectives that may be noted to energy and design of hvac systems, indoor air quality and thermal comfort and design of smoke control systems. given the importance of this issue, an experimental and numerical study of air infiltration through conventional doors and windows has been explored in iran. to this end, at fir...
a significant problem in multicarrier communication systems is the necessity to reduce the value of papr (peak-to-average power ratio) of transmitting signal. in this thesis we study the effect of the system parameters such as coding and modulation types on papr and ultimate ber in a mc-cdma system. in this study we consider fading channel as well as the nonlinearity of transmitter’s amplifier ...
since it is essential to deliver smoothed sinusoidal voltage to the customers, diagnosing power quality (pq) events has played important role in power delivery and conversion. this diagnostic scheme should be accurate to classify pq events from other events in power system. also it should be fast enough to rapidly mitigate pq events. in this paper, an algorithm based on core vector machine (cvm...
this paper presents a new control method for a three-phase four-wire unified power quality conditioner (upqc) to deal with the problems of power quality under distortional and unbalanced load conditions. the proposed control approach is the combination of instantaneous power theory and synchronous reference frame (srf) theory which is optimized by using a self-tuning filter (stf) and without us...
active filters have proven to be more effective than passive techniques to improve power quality and to solve harmonic and power factor problems due to nonlinear loads. this paper proposes a control scheme based on the instantaneous active and reactive power. the inverter of this active filter is a three-phase, two-level converter. space vector technique is used as modulators and pattern genera...
the methods which are used to analyze microstrip antennas, are divited into three categories: empirical methods, semi-empirical methods and full-wave analysis. empirical and semi-empirical methods are generally based on some fundamental simplifying assumptions about quality of surface current distribution and substrate thickness. thses simplificatioms cause low accuracy in field evaluation. ful...
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unlike traditional power grids, smart grids have the advantage of bidirectional power flow and having distributed generations. distributed generation systems are usually supplied by renewable sources which can cause unpredicted voltage fluctuations as a result of being intermittent. while traditional compensating devices deal with the problem of voltage fluctuation and reduced power quality wit...
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