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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

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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
Predicting the Delivery Time of Public School Building Projects Using Nonlinear Regression

Authors: Zeyad S. M. Khaled --- Raid S. Abid Ali --- Mussab Faleh Hassan
Journal: Engineering and Technology Journal مجلة الهندسة والتكنولوجيا ISSN: 16816900 24120758 Year: 2016 Volume: 34 Issue: 8 Part (A) Engineering Pages: 1538-1548
Publisher: University of Technology الجامعة التكنولوجية

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Abstract

The delay in delivering public school building projects in Iraq is one of the major problems that face the construction of new school buildings. In order to enable the concerned governmental agencies to predict the expected delivery time of these projects at the time of contract assignment, two forecasting modelsare developed to aid in this matter. After reviewing a wide range of literature to determine the most common causes of delay, a questionnaire is distributed to owners, consultants, supervising engineers and contractors engaged in public school building projects. The results of the questionnaire were analyzed using the relative importance index. Nine most important causes of delay in public school building projects were assured by the respondents namely; the contractor's financial status, delayed interim payments, change orders, contractor rank(classification), work stoppages, contract value, experience of the supervising engineers, contract duration and delay penalty. Historical data concerning these causes was extracted from past records of the General Directorate of School Buildings, thennonlinear regressionwasemployedto develop two models (A & B)that can predict the final delivery time of public school building projectshaving (12) and (18) classes separately, where the Levenberg-Marquardt technique was used to develop the mathematical equations.The developedprediction equations show a degree of average accuracy of (97.79%) for schoolshaving (12) classes and (97.11%) for schools having (18) classes,with (R2) for both NLR models of (81.25%) and (87.58%) respectively.


Article
Experimental and Theoretical Study for the Effect of Diesel Fuel Quality Produced in Iraq on Ignition Delay Period

Authors: Saadi Turied Kurdi --- Hassan Abad al-wahab Anial --- Hussein Ahmed Abd Yaqoob
Journal: Engineering and Technology Journal مجلة الهندسة والتكنولوجيا ISSN: 16816900 24120758 Year: 2016 Volume: 34 Issue: 12 Part (A) Engineering Pages: 2258-2271
Publisher: University of Technology الجامعة التكنولوجية

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Abstract

An experimental and theoretical investigation to evaluate the effect of diesel fuel produced in Iraq and blended with ethanol of four stroke single cylinder direct injection diesel engine was conducted. This study focused on the development of an empirical ignition delay equations based on engine experimental data and to analyse the dependency of ignition delay on equivalence ratio, engine brake power fraction, effect of engine speed, and cetane number .The experimental measurements was performed at compression ratio of 22:1 at engine speed ranging from 1100 to 2600 rpm with an increment of 500 rpm, and engine torque ranging from 2 to 10 N.m with an increment of 2 N.m. The experimental data from engine during test have been saved on the computerized program (ECA 100, VDAS) connected to the unit.The results show that the empirical equations of delay period are resulted as a function of ignition pressure, ignition temperature, fraction brake power with better agreement with the experimental data than an empirical equations of delay period which are resulted as a function of ignition pressure, ignition temperature, equivalence for all fuels at all speeds. E0 Basra has the highest value of the cylinder pressure with low speed at variable torque. E10 blended fuel has recorded the lowest value of ignition delay period in all speeds. The experiments also show that the ignition delay period has been found to be decreased with increase of cetane number, ignition pressure, ignition temperature, equivalence ratio, and the fraction brake power.


Article
Delay Time Reduction in VCSELs by Optimizing Laser Parameters

Author: Hisham K. Hisham
Journal: Iraqi Journal for Electrical And Electronic Engineering المجلة العراقية للهندسة الكهربائية والالكترونية ISSN: 18145892 Year: 2016 Volume: 12 Issue: 2 Pages: 146-154
Publisher: Basrah University جامعة البصرة

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Abstract

An extensive analysis on reducing the turn-on time delay (ton) in vertical cavity surface emitting lasers (VCSELs) has conducted successfully by considering all the recombination rate coefficients R(N) Besides the R(N) coefficients, the impact of other laser parameters such as, injection current (Iinj), laser cavity volume (V),mirror reflectivity (R), and operating temperature (T) also have investigated. Unlike pervious studies, the temperature dependence (TD) of ton is calculated according to TD of laser parameters instead of well-known Pankove relationship. Results showed that, ton can be reduced by increasing the Iinj and/or the Ni. Meanwhile, the ton increases by increasing the R(N) coefficients. Also, results showed that the ton can be reduced by increasing the R-level or by optimizing laser cavity volume.

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