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نتائج البحث: 4 من أصل 29

تعزيز اداء اتصالات الراديو عبر الليف احادي ومتعدد الطول الموجي بواسطة تقنية التضمين == Performance Enhancements of Single And Multi - Wavelength Radio Links Over Fiber By Modulation Technique

اسم المؤلف: مصطفى عبد الهادي جليل

اسم المشرف: عايد خلف محمد

الموضوع العام: هندسة الكهرباء والالكترون والاتصالات

السنة: 2014

الموضوع الدقيق: هندسة الاتصالات

الدرجة: ماجستير

الجامعة: الجامعة التكنولوجية - قسم الهندسة الكهربائية

اللغة: الانكليزية

مكان الجامعة: بغداد

الصفحات الاولى:

المستخلص: تم تطوير تكنولوجيا الراديو عبر الالياف منذ اواخر القرن العشرين، وتم استخدامها في مجموعة من التطبيقات لانظمة الاتصالات ويعتبر الراديو عبر الالياف هو الجيل المقبل من انظمة الاتصالات لما يمتاز به من العديد من المزايا مقارنة مع النظام التقليدي مع توهين منخفض | Radio - over - Fiber (RoF) technology has been developed since the late 20th century and has been used efficiently in a range of applications for communication systems. Radio over fiber system is the next generation of communication systems because it has many advantages compared with conventional system with low attenuation, enormous bandwidth of optical fiber, and extension of existing coverage and capacity. RoF system refers to the radio signals which are modulated with optical signal and transmitted over optical fiber link from Central Office (CO) to the Remote Nodes (RNs).In this work, several RoF systems have been designed and simulated with different modulation techniques using commercial software package called “Optisystem v.12”. Furthermore, these systems were compared with each other to check for better performance. These systems are presented as follows : The first system is RoF with Quadrature Phase Shift Keying (QPSK), 16 - Quadrature Amplitude Modulation (16 - QAM), and 64 - QAM schemes with and without OFDM technique. The simulation results of this system show that the Signal to Noise Ratio (SNR) for 64 - QAM - OFDM higher than SNR for QPSK, 4 - QAM and 16 - QAM with OFDM at 10 - 9 symbol error, after 50 km of SMF length without any amplification or compensation techniques. In addition, also SNR for 64 - QAM - OFDM higher than SNR for other techniques in this work after 160 km of fiber length.The second system is the RoF with QPSK and 16 - QAM schemes with Digital Signal Processing (DSP) unit in the receiver side. The simulation results of this system show that the Error Vector Magnitude (EVM) for QPSK scheme with DSP unit is 14.5% and 85.5% without DSP unit after 50 km of fiber length. Furthermore, the EVM for 16 - QAM with DSP unit is 7.5%, but the EVM for the same system without DSP unit is 91%. In addition, the EVM for QPSK with DSP equal to 11.5%, but the EVM for 16 - QAM with DSP equal to 9% after 160 km of fiber length.The third system is RoF system with two multiplexing techniques, 8×10 Gbps WDM - RoF system and 4×5 Gbps SCM - RoF system, have been simulated with 4 - QAM - OFDM, 16 - QAM - OFDM and 64 - QAM - OFDM schemes. The fourth system was to combine the techniques of wavelength division multiplexing (WDM) and subcarrier multiplexing (SCM) to increase the capacity of the system by 20×8 Gbps data rate. The simulation results show that the SCM - WDM - RoF with 64 - QAM gives high SNR compared with SCM - WDM - RoF system with other modulation schemes which have been used in this work.

تحسين الاستقرارية باستخدام التوليد الموزع في شبكة النجف الاشرف الكهربائية == Stability Enhancement Using Distributed Generation In Al - Najaf Al - Ashraf Electrical Network

اسم المؤلف: زيد طارق حسن

اسم المشرف: رشيد حميد الربيعي

الموضوع العام: هندسة الكهرباء والالكترون والاتصالات

السنة: 2014

الموضوع الدقيق: هندسة الكهرباء - قدرة ومكائن

الدرجة: ماجستير

الجامعة: الجامعة التكنولوجية - قسم الهندسة الكهربائية

اللغة: الانكليزية

مكان الجامعة: بغداد

الصفحات الاولى:

المستخلص: ان عمل وتركيب نظام التوزيع يتغير مع اضافة وحدات التوليد الموزع (DG )، حيث انها تؤثر على خسائر القدرة، الاستقرارية، الفولطية، جودة الطاقة وكميات اخرى، لذلك اختيار الموقع الامثل والحجم وعدد وحدات التوليد الموزع (DG ) ضروري لتجنب التاثيرات السلبية على نظا | The operation and structure of distribution system are changing with the integration of distributed generation (DG), where the DG may have effect on power losses, stability, voltage profile, power quality and other quantities, therefore the optimization of location , size and number of DG are necessary to avoid the negative impacts on electric power system.In this work, the Particle Swarm Optimization (PSO) technique is used to find the optimal number and locations of DG in order to minimize the active power losses. The thermal limit of transmission lines and transformers was studied in cases , with DG and without DG, to detect the lines or transformers which exceed the limit in order to processed it. The voltage stability of distribution network has been investigated, using L index (which aims to detect the vulnerable load buses of an electrical power system). Also the rotor angle transient stability of DG units has been calculated to specify the critical clearing time (CCT) of each circuit breaker in distribution network when one of transmission lines is exposed to three phase to ground fault. The developed algorithm has been verified using two test systems IEEE 33 - bus distribution system and the WSCC 9 - bus test system, furthermore applied to a part of Iraqi distribution network (Al - Najaf Al - Ashraf distribution network). Two softwares are used in this work , the first is Matlab R2013a for implementation of the PSO and voltage stability algorithms while the second software is Power World Simulator 15 for implementation of the thermal limit of transmission lines and transformers, and rotor angle transient stability of DG units.DG contributed significantly to reduce the power losses in Al - Najaf Al - Ashraf distribution network, where there is a reduction by about 96% in active losses. Also DG processed the overload of large substations and the stability of buses in the network.

تصميم وتصنيع والتحقق من الخلية الشمسية ذات الصبغة الحساسة للضوء == Design, Fabrication And Verification of Dye Sensitized Solar Cell DSSC

اسم المؤلف: صابرين سمير حسان

اسم المشرف: ثائرة زكريا الطيار

الموضوع العام: هندسة الكهرباء والالكترون والاتصالات

السنة: 2014

الموضوع الدقيق: هندسة الالكترونيك

الدرجة: ماجستير

الجامعة: الجامعة التكنولوجية - قسم الهندسة الكهربائية

اللغة: الانكليزية

مكان الجامعة: بغداد

الصفحات الاولى:

المستخلص: Solar cells are considered a promising technology and renewable, in view of increasing in the electro - optical energy. The continual enhancement in solar cell efficiency by searching for new concepts and techniques, which should grow since it is considered as one of the important sources of energy of the future.This work introduces a type of solar cells that employs photosensitive organic dye. These cells use thin membrane of Titanium dioxide material as nanoparticles covered by an organic dye, which absorbs solar energy (like the chlorophyll in green leaves) to be converted into electrons that are injected into the Titanium dioxide layer, which serves as electron collector. In addition, it has an electrolyte solution to compensate for the electrons lost by the organic dye molecules.The cell's positive terminal was prepared from the deposition of a thin membrane of Titanium dioxide, of 22 micrometer thickness on a conductive glass electrode , followed by heat treatment at 450? for 30 minutes. Three organic dyes were used, two of (Cherry juice mixed with Hibiscus and the Berries juice) which were natural dyes, and the other synthetic, the "Eosin" as an industrial dye. Small quantities of Iodine and Potassium Iodide were dissolved in Ethyl Alcohol of 99.9% concentration in order to prepare the electrolyte solution. As to the negative terminal, it was prepared from the deposition of a graphite layer, used in pencils, onto a conducting glass electrode. The final stage involved the assembly of the different prepared cell components and tested.The equipment used in this work included spectrum analyzer for provision of absorption spectra for the three dyes.The cells have been tested by exposure to light of 100W/cm2 to obtain I - V characteristic curve and the greatest current is obtained with the Cherries and Hibiscus cell was 6.205 mA/cm2 and the maximum voltage 0.569 V. As to the Berries dye cell, the maximum current is found 4.35 mA / cm2 and its maximum voltage 0.607 V. The maximum current and voltage for the Eosin dye cell are found to be 1.32 mA/ cm2 and 0.651V.The conversion efficiency for the Cherry and Hibiscus dye cell is found to be 1.9%, the Berries dye cell 1.5% and for the Eosin dye 0.5%.

تمييز قزحية العين باستخدام التحويل الموجي والشبكات الاصطناعية

اسم المؤلف: احمد عز الدين عبد الله

اسم المشرف: هديل نصرت عبد الله

الموضوع العام: هندسة الكهرباء والالكترون والاتصالات

السنة: 2014

الموضوع الدقيق: هندسة الالكترونيك

الدرجة: ماجستير

الجامعة: الجامعة التكنولوجية - قسم الهندسة الكهربائية

اللغة: الانكليزية

مكان الجامعة: بغداد

الصفحات الاولى:

المستخلص: التعرف على قزحية العين هي تقنية القياس الحيوي التي تتناول تحديد الهوية على اساس قزحية الانسان. يعتبر تميز القزحية من انواع التكنولوجيا الحيوية الاكثر دقة المتاحة اليوم بالمقارنة مع انواع كثيرة من التقنيات البيومترية المستخدمة مثل : مسح بصمات الاصابع، التعر | Iris Recognition is a Biometric Technology which deals with identification based on the human iris. It is considered to be the most accurate biometric technology available today compared with many kinds of biometric technologies used, like Fingerprint scanning, Face recognition, Voice recognition and Hand geometry scanning because it has some advantages, such as uniqueness, stability and high recognition rate etc., makes iris recognition so accurate.In this proposed system, two database systems are used. The first is CASIA database system (version 1.0)(Chinese Academy of Sciences Institute of Automation). And, the second is Real database system by using real persons (each with many images) for recognition through camera Mobile Type of Galaxy Note3. An approach to get more accuracy of the offline iris recognition is composed of many steps : capturing the iris image, determining the location of the iris boundaries, normalization, preprocessed using median filter to remove noise, using wavelet transform for two types of filter, Haar and Daubechies, in order to extract the features and finally using the matching by artificial feed forward neural network with back propagation algorithm (FFBNN) for training and testing iris image.In CASIA system, the iris recognition rate for Haar filter was 84.2% and for Daubechies filter was 92.8%, while in the real system, iris recognition rate for Haar filter was 90% and for Daubechies filter was 98.7%. This means the Daubechies filter is the best in execution time and mean square error from the Haar filter. Finally, efficiency of this system is logical, because the performance measurement of False Acceptance Rates was reasonable. The results and the experiments were implemented by P4 computer and the software package MATLAB (R2011a).