research centers


Search results: Found 19

Listing 1 - 10 of 19 << page
of 2
>>
Sort by

Article
Modulation of Chaos with Optoelectronic Feedback in Semiconductor Laser
تضمين اشارات الشواش بالتغذية العكسية الكهروضوئية لليزر اشباه الموصلات

Authors: Maha N. Adnan مها ناظم عدنان --- Kais A. Al Naimee قيس عبد الستار النعيمي
Journal: Iraqi Journal of Science المجلة العراقية للعلوم ISSN: 00672904/23121637 Year: 2016 Volume: 57 Issue: 4C Pages: 2849-2862
Publisher: Baghdad University جامعة بغداد

Loading...
Loading...
Abstract

The modulation of chaotic behavior in semiconductor laser with A.C coupling optoelectronic feedback has been numerically and experimentally reported. The experimental and numerical studying for the evaluation of chaos modulation behavior are considered in two conditions, the first condition, when the frequency of the external perturbation is varied, secondly, when the amplitude of this perturbation is changed. This dynamics of the laser output are analyzed by time series, FFT and bifurcation diagram.

سلوك تضمين الشواش في ليزر اشباه الموصلات ذو التغذية العكسية الكهروبصرية تم دراسته مختبريا وعدديا . الدراسات النظرية والمختبرية لتطور سلوك تضمين الشواش تحدد بشرطين , الشرط الاول عندما يكون تردد الاضطراب الخارجي متغير , اما الثاني عندما تكون سعة الاضطراب الخارجي متغيرة. دينامكية الخرج الليزري تفسر باستخدام تغير اشارة الشواش مع الزمن , تحويلات فورير والمخطط التشعب.

Keywords

Chaos --- Feedback --- Modulation --- Bursting


Article
Chaos synchronization delay in semiconductor lasers with optoelectronic feedback
زمن تأخير تزامن الشواش في ليزر شبة الموصل للشبكات الكهروبصرية

Authors: Atyaf Adnan اطياف عدنان فرحان --- Kais Al-Naimee قيس النعيمي --- Sudad S. Ahmed سؤدد سلمان احمد
Journal: Iraqi Journal of Physics المجلة العراقية للفيزياء ISSN: 20704003 Year: 2016 Volume: 14 Issue: 30 Pages: 18-23
Publisher: Baghdad University جامعة بغداد

Loading...
Loading...
Abstract

In this work we reported the synchronization delay in semiconductor laser (SL) networks. The unidirectional configurations between successive oscillators and the correlation between them are achieved. The coupling strength is a control parameter so when we increase coupling strength the dynamic of the system has been change. In addition the time required to synchronize network components (delay of synchronization) has been studied as well. The synchronization delay has been increased by mean of increasing the number of oscillators. Finally, explanation of the time required to synchronize oscillators in the network at different coupling strengths.

في هذا العمل قمنا بتوضيح زمن تأخير التزامن في ليزر شبة الموصل للشبكات الكهروبصرية. الترتيب الاحادي الاتجاه بين كل متذبذبين متتاليين والتزامن فيما بينهم تم الحصول علية. حيث ان قوة الترابط هي المتغير المتحكم في التزامن. عند زيادة قوة الترابط فأن حركة النظام سوف تتغير بالاضافة الى ذلك الزمن اللازم للتزامن في الشبكات ( زمن التأخير في التزامن ) ايضا تم دراستة واخيرا, تم توضيح الزمن اللازم لتزامن المذبذبات في الشبكات لقوى ربط مختلفة. حيث نلاحظ ان زمن التأخير في التزامن يزداد بزيادة عدد المذبذبات.


Article
Attractor selection in semiconductor laser chaos generated by optoelectronic feedback
انتخاب الجاذب في شواش ليزر شبه الموصل المتولد بواسطة التغذية الاسترجاعية الكهروبصرية

Loading...
Loading...
Abstract

In this paper, an experimental and numerical study for the evolution of the non-linear dynamics of semiconductor laser has been done under two conditions, when the dc bias current of Semiconductor laser is varied, and when the feedback strength is varied. These dynamics were analyzed by time series and their extracted(FFT) power spectrums, phase diagrams (attractors),inter-spike intervals(ISI), these measurements enhanced by bifurcation diagram which explained the chaotic regimes. The stability states using different control parameters have been demonstrated. The role of control parameters of laser such as: dc bias current and feedback strength is proved in spiking generation and chaos control in the laser output.

تم في هذا البحث اجراء دراسة تجريبية ونظرية لتطور الديناميكية غير الخطية لليزر شبه الموصل تحت شرطين هما تغير تيار الانحياز لليزر شبه الموصل وتغير قوة الاسترجاعية .وقد تم تحليل هذه الديناميكيات بواسطة السلاسل الزمنية واطياف القدرة المستخرجة (FFT),مخططات الطور(الجاذب),والفواصل بين الارتفاعات(ISI),وهذه القياسات تعززت بواسطة مخطط التشعب والذي وضح الانظمة الشواشية.وقد توضحت حالات الاستقرار باستخدام معلمات السيطرة المختلفة.تم اثبات دور معلمات السيطرة لليزر مثل:تيار الانحياز وقوة الاسترجاعية في توليد الارتفاعات والسيطرة على الشواش في نتاج الليزر.


Article
Design of Fuzzy-Like Position Controller for Permanent Magnet Stepper Motor

Authors: Farazdaq R. Yasien1 --- Zaid M. Khudher2
Journal: IRAQI JOURNAL OF COMPUTERS,COMMUNICATION AND CONTROL & SYSTEMS ENGINEERING المجلة العراقية لهندسة الحاسبات والاتصالات والسيطرة والنظم ISSN: 18119212 Year: 2016 Volume: 16 Issue: 1 Pages: 84-91
Publisher: University of Technology الجامعة التكنولوجية

Loading...
Loading...
Abstract

Abstract –Permanent Magnet Stepper Motor (PMSM) is defined as a high nonlinear dynamics, MIMO electromechanical incremental actuator broadly applied as a position device. The closed loop control system is proposed to enhance the performance of PMSM from the load change, steady state error, and the parameters variation that appear in the open loop control. The proposed closed loop system is based on the Field Oriented Control (FOC). Fuzzy PID controller is proposed as an intelligent controller for the exact linearized system. The Feedback Linearization (FBL) technique is based on transforming the complex nonlinear model of PMSM into exact linearized model, unlike the Jacobian Linearization, which is based on linearizing the dynamics of the motor around operating point. The results of the proposed controller were compared with conventional PID on the exact linearized model and Fuzzy PID Controller on the nonlinear model of the PMSM. Robustness of the proposed controller was tested under parameters and load variation.


Article
Master students’ feedback about the teaching and learning process in the College of Nursing, Hawler Medical University
ملاحظات طلاب الماجستير حول عملية التعليم والتعلم في كلية التمريض، جامعة هولير الطبية

Authors: Dara Abdulla Al-Banna --- Norhan M. Zaki --- Jawdat Mamand ALhag Baker --- Nazar Ali Doski
Journal: Zanco Journal of Medical Sciences مجلة زانكو للعلوم الطبية ISSN: 19955588/19955596 Year: 2016 Volume: 20 Issue: 3 Pages: 1433-1439
Publisher: Hawler Medical Univeristy جامعة هولير الطبية

Loading...
Loading...
Abstract

Background and objective: Systems for evaluation of teaching and course quality in higher education institutions have long been established and are becoming increasingly common in many developed and developing countries. This study was carried out to identify and assess the feedback of master students in the College of Nursing.Methods: The study is a mixture of quantitative and qualitative design. The study sample included all master students who had attended the master course within two academic years (2012-2014) in the College of Nursing, Hawler Medical University. A formal questionnaire was used to obtain master students’ feedback, and an interview was used as the method of data collection.Results: The mean age of the participants was 33 years for males and 29 years for females. Results revealed that feedback responses as a general were good in all factors underlining the study, and the lowest scores were shown in items related to teacher-student’s relationship and classroom organization.Conclusion: Master students’ feedback was positive for most of the evaluation factors except teacher-student relationship and some items related to classroom organization.


Article
Synchronization in Optically Coupled Chaotic Systems by Optical Feedback

Authors: Younis T. Younis --- Salam K. Musa --- Sora F. Abdalla --- Ahmed K. Ahmed --- et al.
Journal: Iraqi Journal of Applied Physics المجلة العراقية للفيزياء التطبيقية ISSN: 18132065 23091673 Year: 2016 Volume: 12 Issue: 1 Pages: 11-16
Publisher: iraqi society for alternative and renewable energy sources and techniques الجمعية العراقية لمصادر وتقنيات الطاقة البديلة والمستجدة

Loading...
Loading...
Abstract

An experimentally observations of chaos synchronization have been investigated between two optically coupled laser diodes. Two schemes of optical injection, bidirectional and unidirectional optical injections have been used. One of the two lasers MLD exhibits optical chaos due to external optical feedback by fiber mirror and the other laser diode SLD exhibits optical chaos by optical injection from the first one. The chaotic dynamics of both lasers were a function of laser diodes drive current. Synchronization and Anti-synchronization between two coupled laser diodes have been observed, and ensured by different measurements like time series matching, correlation diagram (phase form) of amplitudes of coupled chaotic signals ,spectrum components coinciding of coupled chaotic signals have been used for both injection schemes. Cross correlation function has been used to measure quality of synchronization in unidirectional injection scheme and it was a function of slave laser diode's current.


Article
Optimization of Eye Diagram Based on Adaptive Decision Feedback Equalizer for High Speed Digital System

Author: Amenah. I. Kanaan
Journal: Tikrit Journal of Engineering Sciences مجلة تكريت للعلوم الهندسية ISSN: 1813162X 23127589 Year: 2016 Volume: 23 Issue: 3 Pages: 105-115
Publisher: Tikrit University جامعة تكريت

Loading...
Loading...
Abstract

Eye diagram used in a lot of radio and telecommunication application, but it can also be used in digital signal integrity. This kind of analysis is a common indicator of performance in digital transmission systems. As integration density and data rates increase, dispersive losses, reflections and crosstalk can severely degrade signal integrity. Fortunately, these effects are linear processes. Accordingly, simple, on-chip signal processing techniques can compensate for them. In this paper we introduce an approach to improve eye diagram for data transmission that indicate the signal strength by using adaptive Decision Feedback Equalizer (DFE) in receiver circuits of digital system. The simulation results are presented to validate the efficiency of the proposed method.


Article
Optimization of Eye Diagram Based on Adaptive Decision Feedback Equalizer for High Speed Digital System

Author: Amenah. I. Kanaan
Journal: Tikrit Journal of Engineering Sciences مجلة تكريت للعلوم الهندسية ISSN: 1813162X 23127589 Year: 2016 Volume: 23 Issue: 3 Pages: 105-115
Publisher: Tikrit University جامعة تكريت

Loading...
Loading...
Abstract

Eye diagram used in a lot of radio and telecommunication application, but it can also be used in digital signal integrity. This kind of analysis is a common indicator of performance in digital transmission systems. As integration density and data rates increase, dispersive losses, reflections and crosstalk can severely degrade signal integrity. Fortunately, these effects are linear processes. Accordingly, simple, on-chip signal processing techniques can compensate for them. In this paper we introduce an approach to improve eye diagram for data transmission that indicate the signal strength by using adaptive Decision Feedback Equalizer (DFE) in receiver circuits of digital system. The simulation results are presented to validate the efficiency of the proposed method.


Article
Optimal and Robust Tuning of State Feedback Controller for Rotary Inverted Pendulum

Authors: Hazem I. Ali --- Rasha Mohammed Naji
Journal: Engineering and Technology Journal مجلة الهندسة والتكنولوجيا ISSN: 16816900 24120758 Year: 2016 Volume: 34 Issue: 15 Part (A) Engineering Pages: 2924-2939
Publisher: University of Technology الجامعة التكنولوجية

Loading...
Loading...
Abstract

This paper presents the design and implementation of optimal and robust state feedback controller for rotary inverted pendulum system. The Particle Swarm Optimization (PSO) method is used to find the optimal values of the state feedback gains subject to time response specifications and H_∞ constraints. To improve the tracking of the system, a robust state feedback plus integral controller is designed. The simulation results show that the proposed controller can effectively stabilize the pendulum at the upright position. Further, the proposed controller can compensate the variations in system parameters. The effectiveness of the proposed controller is verified experimentally using real rotary inverted pendulum.


Article
An Enhancement Method Based on Modifying CFB Mode for Key Generation in AES Algorithm

Authors: Dalal N.Hammod --- MahaA.Hamood Al-Rawi --- Hasanen S. Abdulah
Journal: Engineering and Technology Journal مجلة الهندسة والتكنولوجيا ISSN: 16816900 24120758 Year: 2016 Volume: 34 Issue: 6 Part (B) Scientific Pages: 759-768
Publisher: University of Technology الجامعة التكنولوجية

Loading...
Loading...
Abstract

There are two very important characteristics in the block cipher, the amount of time for encryption process and key complexity which caused increasing the complexity of encryption process. This research aims to enhance the key generation of Advanced Encryption Standard (AES) algorithm with high efficiency. The proposed enhancement method architecture based on modifying cipher feedback (MCFB) mode which produce key block from each key generation step in addition to represent current output that is repeated lyre used as input to produce next key block. In the block cipher encryption step, two processes are implemented: Substitution bytes process and Shift rows process. This proposed method improves the performance, efficiency, and speed of the encryption algorithm.

Listing 1 - 10 of 19 << page
of 2
>>
Sort by
Narrow your search

Resource type

article (19)


Language

English (14)

Arabic and English (3)

Arabic (2)


Year
From To Submit

2016 (19)