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Scientific Information Database (SID) - Trusted Source for Research and Academic Resources
Scientific Information Database (SID) - Trusted Source for Research and Academic Resources
Scientific Information Database (SID) - Trusted Source for Research and Academic Resources
Scientific Information Database (SID) - Trusted Source for Research and Academic Resources
Scientific Information Database (SID) - Trusted Source for Research and Academic Resources
Scientific Information Database (SID) - Trusted Source for Research and Academic Resources
Scientific Information Database (SID) - Trusted Source for Research and Academic Resources
Scientific Information Database (SID) - Trusted Source for Research and Academic Resources
Title: 
Author(s): 

Issue Info: 
  • Year: 

    0
  • Volume: 

    1
  • Issue: 

    4
  • Pages: 

    -
Measures: 
  • Citations: 

    0
  • Views: 

    912
  • Downloads: 

    0
Keywords: 
Abstract: 

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

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Issue Info: 
  • Year: 

    1387
  • Volume: 

    1
  • Issue: 

    4
  • Pages: 

    37-49
Measures: 
  • Citations: 

    0
  • Views: 

    1167
  • Downloads: 

    0
Abstract: 

یکی از موضوع های مهم در عرصه تجارت الکترونیک، مساله رعایت قانون حق کپی (Copyright) محصولات دیجیتالی است. واترمارکینگ دیجیتالی، یکی از روش هایی است که برای حل این مساله ارایه شده است و نسبت به روش هایی مثل رمزنگاری و امضای دیجیتالی، که در حال حاضر برای رفع این مشکل استفاده می شوند، از امنیت بیشتری برخوردار است. در این مقاله، تعدادی از روش های واترمارکینگ موجود، ازجنبه های مختلف مورد بررسی قرار گرفته اند. سپس یک روش ترکیبی جدید برای واترمارکینگ تصاویر با فرمت BMP ارایه شده است. این روش واترمارک را در دامنه فرکانسی تصویر با استفاده از دو تبدیل DCT و DWT، جاسازی می کند و فرآیند استخراج را بدون استفاده از تصویر اصلی انجام می دهد. این روش در برابر حملات JPEG و برش (Cropping) و تغییر اندازه (Scaling) بسیار مقاوم است.

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

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Issue Info: 
  • Year: 

    1387
  • Volume: 

    1
  • Issue: 

    4
  • Pages: 

    11-25
Measures: 
  • Citations: 

    0
  • Views: 

    397
  • Downloads: 

    0
Abstract: 

امروزه میکروموتورها کاربردهای زیادی در صنایع مدرن دارد، با این حال منابع چندانی در معرفی این نوع موتورها در دسترس نیست. برای رفع این مشکل و ایجاد زمینه مناسب برای آشنایی پژوهشگران با این تکنولوژی مدرن، در این مقاله بررسی ابعاد مختلف این نوع از موتورها مورد توجه قرار گرفته است. ابتدا ساختارهای مختلف این موتورها و چالـش های مربوط به هر ساختار بررسی شده و در ادامه مقایسه ای بین ساختارهای مختلف از لحاظ معیارهایی چون راندمان، چگالی انرژی، قدرت بر واحد حجم و ابعاد نیروهای تولیدی صورت گرفته، مزایا و معایب هر کدام بررسی شده است. همچنین روش های ساخت میکروموتورها و برخی از کاربردهای آنها شرح داده شده است.

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

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Issue Info: 
  • Year: 

    1387
  • Volume: 

    1
  • Issue: 

    4
  • Pages: 

    27-35
Measures: 
  • Citations: 

    0
  • Views: 

    787
  • Downloads: 

    0
Abstract: 

مسـاله شـناسایی سـیستم عـبارت است از تخـمین یک مـدل از روی سـیستم عملی با استفاده از اطلاعـات ورودی - خروجی آن سیستم. هدف از این مقاله، مطالعه و بررسی سیستم خط تمپرمیل نورد سرد مجتمع فولاد مبارکه، تست عملی و شناسایی این سیستم، ارایه مدل مناسب، مقایسه با داده های واقعی و شبیه سازی آن می باشد. بدین منظور در ابتدا انواع روش های شناسایی را نام برده، سپس مراحل مدل سازی را شرح می دهیم. در ادامه سیستم اعمال نیرو بر سطح ورق و تنظیم فاصله غلتک ها در خط تمپرمیل را شناسایی و مدل سازی می کنیم. مقایسه نتایج شبیه سازی با داده های عملی بیانگر این است که مدل بدست آمده بخوبی سیستم تمپرمیل را تقریب می زند.

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

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Issue Info: 
  • Year: 

    1387
  • Volume: 

    1
  • Issue: 

    4
  • Pages: 

    51-59
Measures: 
  • Citations: 

    0
  • Views: 

    3381
  • Downloads: 

    0
Abstract: 

توسط تبدیلات زمان فرکانسی به مانند موجک و نظریه آشوب در استخراج ویژگی از زیرباندها، می توان دقت تشخیص بیماری صرع لب گیجگاهی را در حضور فعالیت پس زمینه سیگنال های ناخواسته و نویز بهبود داد. به منظور تجزیه EEG به زیربانـدهای دلتا، تتـا، آلفا، بتا وگاما از تبدیل موجک استفاده می شود. با استفاده از نظریه آشوب، پارامتر های بعد همبستگی و نمای لیاپانوف به همراه انحراف معیار از زیر باندها استخراج می شوند و سپس با استفاده از شبکه های عصبی و سایر طبقه بندی کننده ها، میانگین و انحراف معیار دقت روش های مختلف جهت افزایش دقت تشخیص صرع در سه حالت مختلف، حالت طبیعی شخص بیمار، مرحله قبل از ورود به مرحله تشنج و در حالت تشنج، در سیگنال های غیر ایستای مغزی مورد بررسی و آزمون قرار گرفته است. نتایج تحقیق بیانگر این حقیقت است که سیستم های استنتاج فازی در یک فضای مشخصه از باندهای مختلف شامل 8 پارامتر، (دقت 96.8% و انحراف معیار (0.7)) و توسط روش متوسط گیری گروهی با ترکیبی از 6 پارامتر (دقت 97.5% و انحراف معیار صفر) بر روش های دیگر برتری داشته اند و برای دسته بندی حالات مختلف صرع مناسب می باشند. این آمار بسیار قابل توجه است، چرا که دقت بررسی های بصری توسط متخصص ترین نورولوژیست ها، متجاوز از 80% نمی باشند.

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

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Issue Info: 
  • Year: 

    1387
  • Volume: 

    1
  • Issue: 

    4
  • Pages: 

    1-10
Measures: 
  • Citations: 

    0
  • Views: 

    1773
  • Downloads: 

    0
Abstract: 

در این مقاله یک الگوریتم کارآمد تشخیص و طبقه بندی ECG تک کاناله مبتنی بر تبدیل موجک را اجرا نموده و به منظور تشخیص و طبقه بندی برخی آریتمی های خطرناک بطنی به کار گرفته و بهبود داده ایم. در اولین مرحله، کمپلــکس های QRS تشخیص داده می شوند. سپس مشخصات هر QRS با شناسایی و تعیین قله های موج های تشکیل دهنده آن و نیز نقاط شروع و پایان کمپلکس QRS تکمیل می گردد. در ادامه قله های موج هایP ،T و نیز نقاط شروع و پایان هر یک تعیین می شود. ما این الگوریتم را با استفاده از داده های حاشیه نویسی شده معروف MIT/BIH Arrhythmia Database و QT Database ارزیابی نمودیم. در الگوریتم پیشنهادی با بکارگیری موجک اسپلاین درجه دوم(quadratic spline) ، کمپلکس QRS و همچنین موج های P وT از انواع نویزها و تداخل های ناخواسته تفکیک شده و تشخیص آریتمی های حاد در بانک اطلاعاتی سیگنال های الکتروکاردیوگرام استاندارد حتی در حضور نویز و تداخل های ناخواسته نیز امکان پذیر می گردد. با استفاده از الگوریتم پیشنهادی میانگین دقت تشخیص آریتمی های تاکیکاردی بطنی VT، بردی کاردیای بطنی، تاکیکاردی فوق بطنی،SVT  فیبریلاسیون بطنی،VFIB  فلاتر بطنی VFL، فلاتر دهلیزیAFL و آریتمی فیبریلاسیون دهلیزی،AFIB  نزدیک به 80% اعلام می گردد.

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

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Issue Info: 
  • Year: 

    1387
  • Volume: 

    1
  • Issue: 

    4
  • Pages: 

    83-90
Measures: 
  • Citations: 

    0
  • Views: 

    1536
  • Downloads: 

    0
Abstract: 

دوک های خواب یکی از مهم ترین شکل موج های زودگذر در سیگنال EEG در حالت خواب می باشند. در اینجا، یک روش دومرحله ای بر پایه شبکه های عصبی مصنوعی برای شناسایی اتوماتیک دوک خواب در یک سیگنال 19 کاناله EEG معرفی می شود که، در مرحله اول، از یک پرسپترون پیش طبقه بندی کننده به منظور افزایش کارایی کلی آشکارسازی و همچنین کاهش زمان محاسبه استفاده می گردد و در مرحله دوم، دوک های خواب منتخب، توسط یک شبکه ی عصبی مصنوعی پس طبقه بندی کننده، دسته بندی می شود. ابزارهای دسته بندی کننده در فـرآیند پس طبقه بنـدی دو شبـکه MLPو RBSVM بودند که عملکرد آنها در انتها مورد مقایسه قرار گرفت. بررسی دیداری سیگنالEEG 19 کاناله ثبت شده از شش سوژه، توسط یک متخصص تشخیص دوک های بصری خواب، نشان مـی دهد که عملکرد RBSVM نسبت به MLPبا آموزش پس انتشار خطا بهتر بوده و دارای حساسیت میانگین %91.4 و آشکار سازی اشتباه %3.85 است.

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

View 1536

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Issue Info: 
  • Year: 

    1387
  • Volume: 

    1
  • Issue: 

    4
  • Pages: 

    71-82
Measures: 
  • Citations: 

    0
  • Views: 

    974
  • Downloads: 

    0
Abstract: 

در این مقاله روش های متفاوت شبیه سازی سیستم های کنترل شبکه، مورد بررسی قرار گرفته، دقت، سرعت و سادگی هر یک از این روش ها، مورد تحلیل قرار می گیرند. همچنین مدل هایبرید یک سیستم، که در نرم افزارMATLAB شبیه سازی شده است، برای بررسی شبیه سازی دینامیک های سیستم معرفی می گردد. سپس در جهت به کارگیری شبیه ساز ns-2، یک تقریب اولر برای دینامیک های سیستم پیوسته، به کار برده می شود. کارآیی این روش ها نسبت به هر دو مجموعه سیستم های کنترل شبکه و سیستم های کنترل بدون شبکه مورد بررسی قرار می گیرد. در انتها ساختارهای مختلف معماری شبکه و تاثیر هرکدام از عوامل اثر گذارنده آن بر عملکرد سیستم کنترلی ازجمله تعداد پلانت ها، سایز حافظه روترهای هر لینک و میزان ترافیکی که بر روی روتر قرار می گیرد، بیان می شوند.

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

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Issue Info: 
  • Year: 

    2018
  • Volume: 

    12
  • Issue: 

    4
  • Pages: 

    1-16
Measures: 
  • Citations: 

    0
  • Views: 

    249
  • Downloads: 

    123
Abstract: 

The integration of Distributed Energy Resources (DER) in power systems can provide the opportunity to supply electricity to customers more efficiently and effectively. The DER includes Distributed Generation (DG) and Demand Side Management (DSM). In a smart grid incorporating automated control and distributed energy systems an effective DSM can alleviate the peak load and shift part of the demand to off-peak hours. The aim of this research is to assess the impact of the DG and the DSM on reliability of the smart distribution system by analyzing different case studies. Roy Billinton test system RBTS Bus2 is used to validate case studies which are performed as a part of this paper. For more practical considerations, a modification of the RBTS Bus2 model is developed to assess the system reliability

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

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Issue Info: 
  • Year: 

    2018
  • Volume: 

    12
  • Issue: 

    4
  • Pages: 

    19-28
Measures: 
  • Citations: 

    0
  • Views: 

    192
  • Downloads: 

    99
Abstract: 

Recently, the renewable resources such as wind farms assumed more attraction due to their features of being clean, no dependency to any type of fuel and having a low marginal cost. The output power of wind units is dependent on the wind speed which has a volatile and intermittent nature. This fact confronts the solution of unit commitment problem with some challenges when a huge amount of wind resources is penetrated and considerable uncertainties are included in the problem. Moreover, the demand of the system has some volatility in comparison with forecasted values. This kind of volatility and stochastic nature is another source of uncertainty in the power system. In this paper, thermal and wind units are incorporated and the optimization problem is solved by the employment of proper probability distribution function and the Monte Carlo simulation approach for dealing with uncertainties. Afterwards, the optimization problem is solved by the use of the binary form of gray wolf optimization algorithm and the minimized total cost will be obtained. Ultimately, the unit commitment schedule and optimal generation of each unit are determined and the optimization results are compared with the solution of genetic algorithm and particle swarm algorithm.

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

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Issue Info: 
  • Year: 

    2018
  • Volume: 

    12
  • Issue: 

    4
  • Pages: 

    29-44
Measures: 
  • Citations: 

    0
  • Views: 

    219
  • Downloads: 

    96
Abstract: 

Due to the specific nature and various limitations in the architecture and resources of mobile wireless networks, AD HOC networks are highly challenging and risky in terms of quality spheres and maintaining such systems. Opportunistic routing provides the opportunity to improve these issues and enhance the network performance appropriately. Meanwhile, due to unspecified exchange routes in this strategy, it is more difficult to support the quality of routing. In this type of routing, decision-making and candidate prioritization are done based on a criterion named “ opportunism” in such a way that this method of prioritization and selection leads to increased instability in intermediate routes. Accordingly, in order to improve this issue, this research introduces a new routing protocol, named “ QoS-Aware and Stable Opportunistic Routing Protocol (QSORP)” . The QSORP is a three-stage protocol that is based on the performance of its stages, this protocol tries to provide quality together with stability in opportunistic routing, depending on the necessities and requirements of this type of routing. The QSORP protocol supports the capability of reducing the complexity of candidate management in addition to effectively support the quality and stability of links. In order to evaluate the QSORP’ s performance and efficiency, this protocol is simulated using the OPNET simulator and then the protocol is compared with two other protocols; ORAC and QEOR. The simulation results indicated the superiority of the proposed protocol based on the following criteria: unstable intermediate routes, the rate of the received data, and network throughput.

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

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Issue Info: 
  • Year: 

    2018
  • Volume: 

    12
  • Issue: 

    4
  • Pages: 

    45-50
Measures: 
  • Citations: 

    0
  • Views: 

    186
  • Downloads: 

    163
Abstract: 

This paper presents indirect field-oriented control method for two-level inverter FED induction motor. This research paper offers a simple switching strategy to provide optimized output torque, speed regulation and also, less switching losses. In addition to enabling fast torque and speed response, this study also offers constant switching frequency. Conventional Hysteresis current controller has two main drawbacks; the first one is the variation of the switching frequency and the second one is more harmonics in motor currents. The aim of the present paper is to describe a novel switching technique, optimal controller, with the smallest possible tracking error and fixed switching frequency. Modeling and simulation of the proposed method are carried out using MATLAB/SIMULINK.

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

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Issue Info: 
  • Year: 

    2018
  • Volume: 

    12
  • Issue: 

    4
  • Pages: 

    51-59
Measures: 
  • Citations: 

    0
  • Views: 

    216
  • Downloads: 

    208
Abstract: 

This paper presents a study on the four-leg VSI based distribution static compensator (D-STATCOM) for compensation of neutral, source & PCC current harmonic distortion, PCC voltage regulation and compensation of unbalanced in current waveform. This solution could be used for three-phase four-wire nonlinear and unbalanced load medium voltage distribution system. The proposed control algorithm is developed based on synchronous reference frame theory with the PI controller. The obtained reference current signal from control algorithm is compared in hysteresis band current controller for a better switching of the D-STATCOM. The performance of the system with implementing the D-STATCOM is also analyzed and compared. The proposed control method is implemented on 11/0. 4kv medium voltage distribution system and provided effective compensation for reactive power and harmonic distortion mitigation. The simulation results are obtained using MATLAB/SIMULINK.

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Issue Info: 
  • Year: 

    2018
  • Volume: 

    12
  • Issue: 

    4
  • Pages: 

    61-69
Measures: 
  • Citations: 

    0
  • Views: 

    922
  • Downloads: 

    509
Abstract: 

Due to the increasing use of renewable energy sources, employing a DC/DC converter as the interface is proliferated. Among various DC/DC topologies, utilizing multi-input converters due to higher reliability and flexibility is more widespread. This paper evaluates the reliability of the multi-input DC/DC converter, besides carrying out cost calculation to achieve a cost-effective and reliable converter. Furthermore, diagrams of various reliability factors versus the converter’ s branches are demonstrated based on mathematical equations and simulation values for both of parallel and standby redundant modes in order to reach an optimal number of branches in each mode. The results show that the optimal number of branches in terms of reliability or cost factor is different and can vary based on some parameters like output power or component’ s type.

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Issue Info: 
  • Year: 

    2018
  • Volume: 

    12
  • Issue: 

    4
  • Pages: 

    71-78
Measures: 
  • Citations: 

    0
  • Views: 

    301
  • Downloads: 

    127
Abstract: 

In this paper,the economic dispatch problem in combined AC-DC systems is studied based on the equivalent losses matrix of power flow.The proposed method starts with calculation of the power flow for the combined AC-DC system,and continues with the calculation of the losses matrix.Afterwards,the economic dispatch problem is calculated by the interior point method.The active powers which are founded by the economic dispatch problem,are used to recalculate the new power flow.The procedure will be iterated until the results convergence.Finally,several simulations carried out on a 14-bus system including five generation units,with and without DC links.

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Issue Info: 
  • Year: 

    2018
  • Volume: 

    12
  • Issue: 

    4
  • Pages: 

    79-88
Measures: 
  • Citations: 

    0
  • Views: 

    194
  • Downloads: 

    122
Abstract: 

It is well-known that the stator Inter-Turn Short Circuit (ITSC) fault detection in vector-controlled Induction Motor (IM) is a very difficult task so far. This is due to the various problems encountered in diagnostic processes resulting from the speed variation and its influence on electrical signals. As a solution, this paper proposes an approach based on the Vold-Kalman Filter Order Tracking (VKF-OT) technique. To this end, stator phase current, quadrature current and rotational speed were monitored at various speeds with and without fault (i. e. healthy and with the ITSC fault) in the Field oriented control (FOC) IM drive. The VKF-OT technique was applied to the monitored currents in order to track the related harmonic components fault, the results are compared to the classical Fourier analysis (FFT). The obtained results proved that the presented approach is more efficient than the FFT technique, especially when the IM is operating under non-stationary speed conditions.

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Issue Info: 
  • Year: 

    2018
  • Volume: 

    12
  • Issue: 

    4
  • Pages: 

    89-97
Measures: 
  • Citations: 

    0
  • Views: 

    206
  • Downloads: 

    103
Abstract: 

The purpose of this research is to study and select the type of engine and circuits for connecting their windings in the generator operating mode of the electric machine unit for the device of converting kinetic and mechanical energy of rotation in the electric one. The design and principle of the device, which transforms the kinetic energy from pressure into an electric one, is proposed. The results of experimental studies on the determination of the most efficient type of electric engine in accordance with the value of the generated power output are presented. According to the results of the experiments, it was determined that a stepper motor DSh 200-1 is more efficient for one rotation in the forward and reverse direction with frequency f = 1. 185 Hz. The processing of experimental research was carried out using integral methods of mathematical physics, namely the trapezoid method. Integration of the received oscillograms allowed to determine the most effective circuit of connection of stepper motor DSh-200-1 stator windings. For one rotation in the forward and reverse direction with frequency f = 1. 185 Hz, the given circuit will provide the power of 0. 164 Watt.

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Issue Info: 
  • Year: 

    2018
  • Volume: 

    12
  • Issue: 

    4
  • Pages: 

    99-107
Measures: 
  • Citations: 

    0
  • Views: 

    206
  • Downloads: 

    159
Abstract: 

This paper presents a wide tuning range, and low noise voltage controlled oscillator (VCO) based on cross-coupled and colpitts structures. The advantages of this work provide a low-phase noise and robust start-up condition, leading to minimized the dc power. In addition, a new structure of the capacitor bank is used in this structure to achieve a wide range of frequency. The proposed circuit is simulated in 0. 18 μ m CMOS process. The designed VCO covers the frequency range of 21. 95 GHz to 24 GHz with a tuning range of 8. 9%. Simulation results show that the phase noise is-120. 5 dBc/Hz at 1MHz offset frequency for 23GHz carrier frequency. Also, power consumption of the VCO is 6. 34 mW under 1. 8 supply voltage, and the figure-of-merit is-191. 68 dBc/Hz.

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Issue Info: 
  • Year: 

    2018
  • Volume: 

    12
  • Issue: 

    4
  • Pages: 

    109-116
Measures: 
  • Citations: 

    0
  • Views: 

    219
  • Downloads: 

    150
Abstract: 

This review paper contains the discussion about performance analysis of high speed 4-2 compressor architectures, starting from the general idea; conventional form for implementation of this building block along with its truth table has been studied. Thereafter, the modified versions which show promise for high speed multiplier implementations along with their benefits and drawbacks were demonstrated and comprehensively analyzed. Following the same principles, an optimized structure for the 4-2 compressor is obtained which has 2 XOR gate level delay for the critical path and contains the least delay among the reported works. As another advantage, because of uniform paths the output waveforms will be free of any glitches. Simulation results for TSMC 0. 18 μ m CMOS technology and 1. 8V power supply using HSPICE have been provided to show the superiority of our designed architecture in terms of the speed performance. Finally, to confirm the correct behavior of proposed compressor, an 8x8 bit multiplier was designed which can operate at the frequency of 500MHz without employing any special multiplication algorithm for partial product generation.

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