البحث — المستودع الرقمي العراقي

المستخلص: مياه الصرف الصناعي لمصافي النفط الناتجة بصورة رئيسية من عمليات تكرير النفط الخام والصناعات التحويلية، مواد التشحيم والبتروكيماويات الوسيطة. هذه السوائل هي المصدر الرئيسي للتلوث البيئي المائي. تتكون مياه الصرف الصناعي من الزيوت والشحوم والمركبات العضوية ا | Petroleum refinery wastewater originating from petroleum industries primarily resulted in refining crude oil and manufacturing fuels, lubricants and petrochemical intermediates. These effluents are a major source of aquatic environmental pollution. The wastewaters are composed of oil and grease, toxic organic compounds along with many other minerals. In this study, wastewater of Al - Najaf petroleum refinery was used as electrolyte solution in the experiments, and the effect of some variables on the removal of organic material as a pollutant in term of COD were studied. The performance of anodic oxidation represented by COD removal was studied using 1 liter batch - mode parallel plate electrochemical reactor at constant initial COD concentration and fixed agitation speed of 250 rpm with the variation of operating conditions that were expected to have a major effect on process. These variables were : electrodes material (platinum, stainless steel, graphite, PbO2, and carbon felt), current densities (5, 15, 25) mA cm - 2 for carbon felt electrode and (10, 30, 50) mAcm - 2 for other electrodes, pH (4, 7, 10), temperatures (25, 40, and 55)?C and with electrolysis time up to 120 minutes. The results show that the direct anodic oxidation process gave the best COD removal percent of 84.88% and 86.27% at 50 and 25 mA cm - 2 current densities for PbO2 and carbon felt anode materials, respectively. The highest COD removal was predicted at pH 4 and the best temperature at 55?C for all electrode types. The reaction was followed by pseudo first - order kinetics rate. As well, it was studied the effect of current density on the current efficiency, instantaneous current efficiency, energy consumption, charge load with the time and calculated activation energy.

بناء معيد ترميز تكراري شبه مثالي للاشارات المرمزة المعتمدة على مخطط تانر Implementation Of Modified Suboptimal Iterative Decoding For Tanner - Graph Based Coded Signals

اسم المؤلف: محمد ثامر نصر

اسم المشرف: احمد عبد الكاظم حمد

الموضوع العام: هندسة الكهرباء والالكترون والاتصالات

السنة: 2016

الموضوع الدقيق: هندسة الالكترونيك والاتصالات

الدرجة: ماجستير

الجامعة: جامعة بابل - كلية الهندسة - قسم الهندسة الكهربائية

اللغة: الانكليزية

مكان الجامعة: بابل

الصفحات الاولى:

المستخلص: في هذا العمل, تم اقتراح خوارزميتين لتحسين اداء معيد الترميز التكراري التجميعي. الاول انجز باضافة رموز ارشاد بين سيل البيانات التي تدخل الى المرمز. في هذه الطريقة, رموزالارشاد ترمز مع البيانات المدخلة (رموز الارشاد المرمزه او الداخليه) مقارنة بالطريقة الاع | In this work, two algorithms were suggested in order to improve the performance of systematic RA decoding. The first one was accomplished by the insertion of pilot symbols between the data stream that entering the encoder. In this way the pilot symbols are encoded along with the input data (encoded or internal pilots) in contrast to the usual way where pilots are inserted after encoding (unencoded or external pilots). The positions where pilots should be inserted are chosen in such a way that to improve the minimum Hamming distance and/or to reduce the error coefficients of the code. Moreover, the known pilots have higher reliability than data and can significantly improve the initial decoding.The second proposed algorithm includes the utilization of the inserted pilots to estimate scaling (correction) factors. Two - dimensional (2D) correction system was suggested in order to enhance the performance of traditional Minimum - Sum (MS) decoding of regular RA codes. By calculating the mean square difference (MSD) between the values of received pilots and the a - posteriori data of bit and check node related to them, which are created by the MS decoder, an adaptive method can be achieved for getting the correction factors.Since encoded pilots in systematic RA code are embedded in data, it is possible to puncture all or part of them to increase the code rate. The pilots still have their effect on increasing the minimum Hamming distance.Extensive simulation tests reveal that the suggested quasi - optimal algorithms supply error performance be able to compare as Sum - Product (SP) decoding whilst maintain less complexity. Practical experiments are carried out by utilizing the capability of data acquisition toolbox supported by MATLAB to provide a hardware interface with the computer sound card. Here, the sound card plays the role of ADC and DAC converter in the physical layer. A different graphical user interfaces (GUI) are designed for the transmitting and receiving terminals to facilitate the selection of different code options. Signals are transmitted over wireless channel using a 2.4 GHz band indoor audio tranceiver. According to the aquired results, the modified coding system outperforms the original one when it is tested over AWGN and fading channels. An improvement may be realized about 1.5 dB and 1.3 dB at BER=?10?^( - 5) for punctured and unpunctured systematic (50,35,3,7) code with adaptive scaling, with three encoded pilots over AWGN channel and about 3.4 dB and 3.3 dB at BER=?10?^( - 4) for punctured and unpunctured systematic (50,35,3,7) code with constant scaling, with two encoded pilots over fading channel.