البحث — المستودع الرقمي العراقي

نتائج البحث: 21 من أصل 46

تحسين تخطيط المسار للروبوتات المتنقلة والمستقلة بالحركة باستخدام خوارزميات الامثلية القائمة على مبدا التجمعات == Improvement of Path Planning For Autonomous Mobile Robots Using Population - Based Optimization Algorithms

اسم المؤلف: فرح مهدي علي

اسم المشرف: نزار هادي عباس

الموضوع العام: هندسة الكهرباء والالكترون والاتصالات

السنة: 2014

الموضوع الدقيق: هندسة الكهرباء

الدرجة: ماجستير

الجامعة: جامعة بغداد - كلية الهندسة - قسم الهندسة الكهربائية

اللغة: الانكليزية

مكان الجامعة: بغداد

الصفحات الاولى:

المستخلص: Autonomous mobile robots are used in various applications such as dangerous regions. These applications demand robust and adaptable methods for path planning.Path planning optimization problem is a fundamental problem for robot navigation; its purpose is to find a collision - free path from the initial position to a target position. Many real - world optimization problems have become increasingly large, complex and dynamic, which require the development of methods and solutions whose efficiency ismeasured by their ability to find acceptable results within a reasonable amount of time.The Artificial Bee Colony (ABC) and Bacterial Foraging Optimization (BFO) algorithms are used for solving hard optimization problems, including path planning. BFO algorithm is a simple and powerful searching technique. On the other hand, Artificial Potential Field (APF) as a real time obstacle avoidance method is quite simple in theory, but it is easy to bring local minimum problem and failing to find a path in the narrow channel. Therefore, a method for hybridizing APF with BFO is introduced to make use of both methods' advantages. This thesis presents efficient and reliable four optimization algorithms to solve the path planning problem. The first two algorithms are developed based on ABC algorithm as global path planning; they specifically are modified version of ABC algorithm called Directed ABC (DABC) algorithm and a new fitness function added to ABC algorithm named Minimum Angles (MAABC) algorithm was developed. The other two algorithms were proposed based on BFO and APF algorithms as local path planning; they were namely improved versions of BFO algorithm with adaptive step size (ASBFO) algorithm and a proposed version of BFO algorithm with an adaptive tumble (ATBFO) algorithm.The developed algorithms were simulated using MATLAB R2011b package. The simulation results showed that these algorithms could find the shortest paths for even crowded environments. Moreover, these algorithmswere compared with other researchers’ work to evaluate their performance. Additionally, a comparison was made between the executing time of the proposed local path planning algorithms (ASBFO and ATBFO algorithms) and the real tracked military robot (e.g., Talon) to verify the capability of the proposed methods. Both algorithms achieved fast run time, approximately three times faster than Talon for complex environment, which made them practically efficient.

تمثيل وتنفيذ العاكس ثلاثي الطور رباعي السيقان بواسطة طريقة المتجه الفضائي بتضمين عرض النبضة == Modeling And Implementation of Space Vector PWM Four - Leg Three Phase Inverter

اسم المؤلف: لؤي كمال عبد القادر

اسم المشرف: فاضل عباس مهدي القرملي

الموضوع العام: هندسة الكهرباء والالكترون والاتصالات

السنة: 2014

الموضوع الدقيق: هندسة الكهرباء

الدرجة: ماجستير

الجامعة: جامعة بغداد - كلية الهندسة - قسم الهندسة الكهربائية

اللغة: الانكليزية

مكان الجامعة: بغداد

الصفحات الاولى:

بناء خوارزمية تزامن لانظمة (OFDM) باستخدام معالجة الاشارة الرقمية == Dsp - Based Synchronization Algorithm Implementation For OFDM System

اسم المؤلف: رائد ستار جبر

اسم المشرف: محمود عبد القادر عبد الستار

الموضوع العام: هندسة الكهرباء والالكترون والاتصالات

السنة: 2014

الموضوع الدقيق: هندسة الالكترونيك والاتصالات

الدرجة: ماجستير

الجامعة: جامعة بغداد - كلية الهندسة - قسم الهندسة الكهربائية

اللغة: الانكليزية

مكان الجامعة: بغداد

الصفحات الاولى:

المستخلص: تعدد الارسال للتردد بالتقسيم المتعامد (OFDM) هو مفتاح تمكين التكنولوجيا لمعظم انظمة الاتصالات اللاسلكية الحالية ذات معدل نقل البيانات العالي. والميزة الرئيسية للـ (OFDM) مقارنة بالطرق التقليدية هو انه يحول القناة ذات النطاق العريض الى قنوات فرعية ضيقة متو | Orthogonal Frequency Division Multiplexing (OFDM) is the key enabling technology for most current high data - rate wireless communication systems. The primary advantage of OFDM over conventional schemes is that it converts a wideband channel into parallel narrowband sub - channels allowing relatively simple channel estimation and frequency domain equalization. It is as an effective technique for coping with channel impairments like multipath propagation and Inter Symbol Interference (ISI) by making use of an appropriate cyclic prefix. One of the major drawbacks of OFDM is that it is more sensitive to synchronization errors than its single carrier counterparts. This thesis describes a real - time implementation of a timing and frequency synchronization for OFDM system using MATLAB software Simulink, DSP processor TMS320C6713 and Code Composer Studio (CCS). The hardware interface converts the baseband signal from the PC to the DSP Processor. Basic transmission and reception performances are evaluated in real time using Real Time data Transfer (RTDX). The practical results and performance evaluation of the synchronization algorithms in OFDM system is presented and discussed. The results are plotted for different offsets of CFO and STO with different values of signal to noise ratio. Also the bit error rate (BER) and the mean square error (MSE) of the system is analyzed. The results show that the time offset more effect than frequency offset because of ISI and ICI occurs when time offset occur in the system. The synchronization algorithm is found to be robust for both CFO and STO simultaneously. It can handle offset of about CFO = 500 Hz and STO = 14 samples simultaneously without wasting extra bandwidth. This algorithm used for synchronization more robust for 16QAM compared with 4QAM modulation.

الموقع الامثل للمعوض التزامني الثابث لشبكة الضغط الفائق العراقية باستخدام الخوارزمية الجينية == Optimal Location of Static Synchronous Compensator (STATCOM) For Iraqi National (400kV) Super High Voltage Grid Using Genetic Algorithm

اسم المؤلف: حسن علي عبد المجيد سلبي البياتي

اسم المشرف: Firas Mohammed Tuaimah

الموضوع العام: هندسة الكهرباء والالكترون والاتصالات

السنة: 2014

الموضوع الدقيق: هندسة الكهرباء

الدرجة: ماجستير

الجامعة: جامعة بغداد - كلية الهندسة - قسم الهندسة الكهربائية

اللغة: الانكليزية

مكان الجامعة: بغداد

الصفحات الاولى:

المستخلص: Transmission networks of modern power systems are becoming increasingly stressed because of the growing demand and restrictions on constructions new lines. One of the consequences of such a stressed system is the threat of losing stability following adisturbance. Flexible AC Transmission System (FACTS) devices are found to be very effective in a transmission network for better utilization of its existing facilities without sacrificing the desired stability margin.The Static Synchronous Compensator (STATCOM) is a shunt device which employs one of the latest technologies of FACTS and power electronic switching devices in electric power transmission systems to control the voltage and power flow. The STATCOMregulates the voltage at its terminal by controlling the amount of reactive power injected into or absorbed from the power system.Whilst the Iraqi National (400 kV) Super High Voltage Grid System suffers from voltage stability problems because of the high variation in the reactive power conditions all over the year seasons. Therefore, this thesis proposed an application of the STATCOM devices to maintain the voltages within the specified limits and enhancing voltage stability for all seasons in the year, as well as reducing the apparent power losses. And in order to reduce therequired installation cost of the STATCOM devices, this performance has been done by using minimum possible size of the reactive power injected or absorbed by the STATCOM devices, while satisfying the stability limits.The benefit of the STATCOM devices depends greatly on how these devices can be placed in the system. The general problem focused in this thesis was how to optimally determine the locations and the sizes of the STATCOM devices that to be installed. For thatreason, it was decided to follow an optimization approach such as a Genetic Algorithm (GA), which is one of the heuristic methods to find the optimum location and the value of installed STATCOM devices.The Newton - Raphson load flow method, with the proposed approach has been examined and tested first on the 5 - bus IEEE test system; the results obtained encouraged us to implement the same approach on the 27 - bus Iraqi National (400kV) SHV Grid System.The real data for Iraqi network have been taken from Iraqi National Control Center (INCC), in the Ministry of Electricity.computer program, written in MatLab environment, was developed to represent the proposed method.

تقنيات النمذجة الذكية في تنبوء حمل الطاقة الكهربائية == Intelligent Modeling Techniques of Electric Power Load Forecasting

اسم المؤلف: يونس محي نصيف

اسم المشرف: حنان ميخائيل داود

الموضوع العام: هندسة الكهرباء والالكترون والاتصالات

السنة: 2014

الموضوع الدقيق: هندسة الكهرباء

الدرجة: ماجستير

الجامعة: جامعة بغداد - كلية الهندسة - قسم الهندسة الكهربائية

اللغة: الانكليزية

مكان الجامعة: بغداد

الصفحات الاولى:

النظام المضبب للتحكم بمشكلة التزاحم لبروتوكول (التحكم في الارسال) في الشبكات المختلطة == A Fuzzy Based TCP Congestion Control For Hybrid Networks

اسم المؤلف: سارة رعد قاسم

اسم المشرف: زينب توفيق باقر

الموضوع العام: هندسة الكهرباء والالكترون والاتصالات

السنة: 2014

الموضوع الدقيق: هندسة الكهرباء

الدرجة: ماجستير

الجامعة: جامعة بغداد - كلية الهندسة - قسم الهندسة الكهربائية

اللغة: الانكليزية

مكان الجامعة: بغداد

الصفحات الاولى:

المستخلص: Transmission Control Protocol (TCP) is designed to deliver seamless and reliable end - to - end data transfer across unreliable networks and is offered connection - oriented, byte - stream service. The Internet’s TCP is probably the most widely used protocol; it is also the most carefully tuned since performance of Internet is largely based on TCP. However, throughput in TCP degrades notably when operated in erroneous networks. In erroneous networks, TCP misinterprets random packet losses and the subsequent packet reordering due to high bit error rate as congestion and invokes congestion control by triggering to fast retransmission and fast recovery, leading to under - utilization of the network resources and affecting TCP performance critically.Many proposals have been used to improve TCP performance in wireless networks. Most of these proposals were based on changing the TCP header and add more complications to the main mechanism. Means of improving performance of TCP over erroneous links were proposed using fuzzy controller in a simple manner (without changing the header) by tracking the delay and the frequencies of the occurrences of timeouts and triple duplicate acknowledgement (3dupacks) to differentiate congestion loss from bit error loss. The first proposal was FReno (Fuzzy+NewReno) but this new algorithm failed to achieve good efficiency. The second proposal was FVegas (Fuzzy+Vegas) and it also failed to improve TCP’s resource utilization. The third proposal was FWestwood (Fuzzy+Westwood) which significantly improved TCP performance. The proposed algorithm was compared against standard TCP variants for different error rates using OMNET++4 version 4.3.1 IDE simulator. FWestwood algorithm helped TCP to distinguish between congestion and packet loss and increase the performance in erroneous wired network, heterogeneous networks, wireless networks and mobile network. Results from simulations showed that in a congested network with (1% to 10%) of random packet loss rate, FWestwood achieved significant improvements in different erroneous networks over other TCP schemes. Also it achieved friendliness fair share of the link with other TCP standards.

التوزيع الامثل للمتحسسات في شبكة المتحسسات اللاسلكية باستخدام خوارزمية الامثلية المستوحاة من نظرية الاسراب == Optimum Sensors Deployment In Wireless Sensor Networks Using Swarm Based Bio - Inspired Optimization Algorithms

اسم المؤلف: هيثم سعدون عفتان

اسم المشرف: نزار هادي عباس

الموضوع العام: هندسة الكهرباء والالكترون والاتصالات

السنة: 2014

الموضوع الدقيق: هندسة الكهرباء

الدرجة: ماجستير

الجامعة: جامعة بغداد - كلية الهندسة - قسم الهندسة الكهربائية

اللغة: الانكليزية

مكان الجامعة: بغداد

الصفحات الاولى:

المستخلص: The increased demand for Wireless Sensor Networks (WSNs) in different areas of application has intensified studies dedicated to the deployment of sensor nodes in the recent past. The deployment of sensor nodes required that some of the key objectives should be satisfied, which are the coverage ratio of the monitoring area and the lifetime of the network.In this thesis, a mathematical model to optimize the coverage ratio and the lifetime of network is developed to ensure a better utility of the WSN. The model is formulated based on several parameters such as the size of the monitoring area, network models, the total number of sensor nodes, visibility requirements, sensing/communication radius, etc.Popular swarm based bio inspired algorithms have been used to optimize the WSN deployment. The coverage optimization process has been carried out by single objective optimization algorithms such as the Ant Colony Optimization (ACO) algorithm, modified version of Particle Swarm Optimization called Discrete PSO (DPSO), Discrete Artificial Bee Colony (DABC) algorithm and a new proposed algorithm called Quantum Artificial Bee Colony (QABC). QABC is based on quantum physical concepts to improve the local search capability of standard ABC algorithm. Thereafter, a multi objective optimization algorithm has been utilized to optimize the coverage ratio and lifetime of WSN. The multi objective optimization has been carried out by Non - dominated Sorting Genetic Algorithm (NSGA - II). All of these algorithms are simple, effective and computationally efficient optimization techniques.The WSN deployment has been simulated using MATLAB 7.12.0 (R2011a) package, NetBeans 7.4 Java integrated development environments, JMETAL 4.5 and Java Universal Network/Graph (JUNG 2.0.1) frameworks. The computer simulation results showed that the proposed algorithm for coverage ratio maximization was up to two times faster than the others. Furthermore, the conducted simulation indicated that the QABC algorithm offered (6%) better solution in terms of coverage in comparison with the others in some cases. Also the results showed that the deterministic deployment can achieve up to (25%) better coverage ratio than the random deployment. In addition, QABC outperformed GA, PSO and ABC algorithms when applied to several test problems. Additionally, the results showed that the NSGA - II algorithm could effectively optimize the network lifetime and coverage ratio and produced good convergent solutions to the Pareto front and was uniformly distributed along it.

تقليل تموج عزم الدوران في طريقة السيطرة المباشرة لعزم الدوران للمحركات الحثية == Torque Ripple Reduction Based Direct Torque Control For Induction Motor Drives

اسم المؤلف: حيدر سالم حميد

اسم المشرف: Prof. Dr. J.H. Alwash | Hanan M. Habbi

الموضوع العام: هندسة الكهرباء والالكترون والاتصالات

السنة: 2014

الموضوع الدقيق: هندسة الكهرباء

الدرجة: ماجستير

الجامعة: جامعة بغداد - كلية الهندسة - قسم الهندسة الكهربائية

اللغة: الانكليزية

مكان الجامعة: بغداد

الصفحات الاولى:

المستخلص: التحكم المباشر لعزم الدوران هو اسلوب التحكم المستخدم في انظمة محرك التيار المتناوب للحصول على سيطرة عزم دوران عالية الاداء. محرك DTC التقليدية يحتوي على زوج من الـ ( hysteresis comparators)، حساب الفيض وعزم الدوران وجدول اختيارالـ ( voltage vector). يت | Direct Torque Control (DTC) is a control technique used in AC drive systems to obtain high performance torque control. The conventional DTC drive contains a pair of hysteresis comparators, a flux and torque estimator and a voltage vector selection table. The torque and flux are controlled simultaneously by applying suitable voltage vectors, and by limiting these quantities within their hysteresis bands, de - coupled control of torque and flux can be achieved. Conventional DTC drives utilizing hysteresis comparators suffer from high torque ripple and variable switching frequency. Several techniques have been developed to improve the torque performance. In this thesis, Proportional - Integral (PI) controller has been presented to improve the system performance which gives better torque and flux response and also reduces the undesirable torque ripple. The most common solution to high torque ripple and variable switching frequency is to use the space vector pulse width modulation (SV - PWM) that depends on the reference torque and flux. The reference voltage vector is then realized by using a voltage vector modulator.The conventional DTC and DTC with PI controller are implemented using Xilinx System Generator (XSG) for MATLAB/Simulink environment through Xilinx blocksets. The design was achieved in VHDL, based on a MATLAB/Simulink simulation model. The Hardware - in - the - Loop (HIL) method is used to verify the functionality of the Xilinx FPGA estimator. The results are obtained and compared with MATLAB/ Simulink results considering the implementation of the proposed model on the Xilinx NEXYS2 Spartan 3E1200 FG320 Kit. The simulations of the DTC - SVPWM were carried out using MATLAB/ Simulink simulation package. The design, implementation and simulation of the overall drive system is performed using MATLAB/Simulink program version 7.13.0.564 (R2011ba) and Xilinx ISE Design Suite 14.2.