البحث — المستودع الرقمي العراقي

نتائج البحث: 6 من أصل 331

استجابة التضمين والضوضاء في قفل الحقن لليزرات التعاقب الكمي == INTENSITY MODULATION RESPONSE AND NOISE IN INJECTION - LOCKING QUANTUM CASCADE LASERS

اسم المؤلف: اخلاص عبد العالي حسين

اسم المشرف: حسين هادي وارد

الموضوع العام: علوم الفيزياء

السنة: 2017

الموضوع الدقيق: الفيزياء

الدرجة: ماجستير

الجامعة: جامعة ذي قار - كلية العلوم - قسم الفيزياء

اللغة: الانكليزية

مكان الجامعة: ذي قار

الصفحات الاولى:

بناء منظومة البلازما الضغط الجوي الغير حرارية للتطبيقات الطبية الحيوية == Construction of Non - thermal Atmospheric Pressure Plasma System for Biomedical Applications

اسم المؤلف: علي فاضل محمد هاشم

اسم المشرف: فاضل خدام فليفل | محمد خماش خلف

الموضوع العام: علوم الفيزياء

السنة: 2017

الموضوع الدقيق: فيزياء البلازما

الدرجة: ماجستير

الجامعة: جامعة كربلاء - كلية العلوم - قسم الفيزياء

اللغة: الانكليزية

مكان الجامعة: كربلاء

الصفحات الاولى:

المستخلص: Recently, the atmospheric pressure non - thermal plasma has attracted great attention in biomedical applications due to the advantages of high e ciency, safety, no toxic residue and low cost. In this work, a homemade plasma jet system was constructed. The system which used in this work was a dielectric barrier discharge (DBD) type atmospheric pressure plasma jet (APPJ). It was applied to generate a non - thermal plasma using an alternating current (AC) power supply (providing voltages up to 7.5 kVp????p and frequencies up to 12 kHz) with two types of noble gases (argon and helium). The system was based on two electrodes con guration, where the rst con guration based on ring - to - plate electrodes structure and the second on double - ring electrodes structure. Each con - guration used two types of Pyrex tube with wall thickness of 3 mm and 0.95 mm. It was found that the ring - to - plate electrodes structure with tube wall thickness of 3 mm generate plasma at high temperature (48.5 C) while, the plasma temperature decreased to 46 C when thetube wall thickness reduced to 0.95 mm. In contrast, the double - ring electrodes structure did not generate plasma when using a tube with wall thickness of 3 mm but, when the tube wall thickness reduced to 0.95 mm, plasma generated at low temperature (34.5 C). The electrical characteristics was investigated to describe the discharge of the argon and helium plasma jets. It was found that the ignition voltage for the helium plasma (4 kVp????p) was lower than the ignition voltage for the argon plasma (4.7 kVp????p). Also through the current discharge, it was con rmed that the plasma system safe and prevents any arcing.The in uence of the higher gas ow rate lead to increase of the plasma plume length and reduction of the plasma jet temperature. The maximum plume length of argon plasma was 23 mm and the temperature at this length was 34 C under the system conditions of 12 kHz, 7.5 kVp????p and gas ow rate of 4 standard litre per minute (slm). In contrast, the maximum plume length of helium plasma was 44 mm and the temperature at this length was 27 C under the same system conditions.The plasma jet was diagnosed by optical emission spectroscopy (OES) to calculate the electron temperature (Te) and density (ne). As well, the presence of active species such as reactive oxygen and nitrogen species (RONS) was con rmed by OES. The lines intensity of the active speciesfor argon and helium plasma jets showed variations in quantity and qual -

دراسة الخواص المغناطيسية لنظام فيريمغناطيسي ذي برم مختلط باستخدام تقريب متوسط المجال == Study of the Magnetic Properties of a Mixed Spin Ferrimagnetic System by Using Mean Field Approximation

اسم المؤلف: اسماء مزعل جاسم

اسم المشرف: حسن عبد ياسر | هادي قاسم محمد

الموضوع العام: علوم الفيزياء

السنة: 2017

الموضوع الدقيق: الفيزياء

الدرجة: ماجستير

الجامعة: جامعة ذي قار - كلية العلوم - قسم الفيزياء

اللغة: العربية

مكان الجامعة: ذي قار

الصفحات الاولى:

المستخلص: In this research it has been investigated the magnetic properties of a mixed spin - 2 and spin - 7/2 lsing binary ferrimagnetic system which is numerically solved by using the mean - field approximation (MFA), for a square lattice and simple cubic one; respectively.The magneto crystalline anisotropies have carefully been changed so as to investigate an interesting phenomenon which is called “Compensation phenomenon” where it has been found that the mixedspin Ising system which is considered has one compensation temperature and ) 4z ( square for a 85 . 2 1 . 3     B D , 85 . 1 1 . 2     B D when the considered system , respectively. Whereas lattice ) 6z ( simple cubic A atoms of for the sublattice anisotropies compensation points multi has in the range  7.1  DA  6.1, 10.4  DA  9.2 for a square and simple cubic lattice, respectively. Besides that it has been studied this phenomenon in the presence of an external magnetic field. We have , 1 . 0 2 . 0     H , , i.e. H lues of t a certain range of negative va found tha gives rise to the multi compensation points. On the other hand, the obtained results indicate that the considered system has experienced first - order and second - order phase transitions, in the planes mA,T , mB ,T respectively. At certain values of sublattices observe that the ordered , one can H , in the absence of A D anisotropies may show the first order phase transition rom the  phases at T  0K SA  2 state to the SB  7 / 2 state, when the value of anisotropyDB decreases.As well, we have examined the phase transitions within the calculation of the free energy function on the basis of Bogoliubov inequality in the plane  f ,T  to obtain precisely results compared of both crystalline for ) TM, ( se ones have been shown in the plane tho sublattices. Our results are encouraged and helpful to support and clarify the characteristic features in a series bimetallic molecularbased magnets. Besides that these magnetic materials have applications in the area of thermo - magneto recording.

دراسة نظرية لعملية انتقال الالكترون خلال بعض التراكيب النانوية == Theoretical Study of Electron Transport Through Some Nanoelectronic Structures

اسم المؤلف: محمد عبد الامير عباس

اسم المشرف: فلاح حسن حنون | لافي فرج البدري

الموضوع العام: علوم الفيزياء

السنة: 2017

الموضوع الدقيق: الفيزياء

الدرجة: ماجستير

الجامعة: جامعة ذي قار - كلية العلوم - قسم الفيزياء

اللغة: الانكليزية

مكان الجامعة: ذي قار

الصفحات الاولى:

تاثير امتزاز الغاز على الخصائص الالكترونية والتركيبية للجرافين المطعم == Effect of the Gas Adsorption on the Electronic and Structural Properties of Doped Graphene

اسم المؤلف: صلاح عبد المهدي خضير

اسم المشرف: حمد رحمن جبر

الموضوع العام: علوم الفيزياء

السنة: 2017

الموضوع الدقيق: فيزياء الالكترونيات

الدرجة: ماجستير

الجامعة: جامعة بابل - كلية التربية للعلوم الصرفة - قسم الفيزياء

اللغة: الانكليزية

مكان الجامعة: بابل

الصفحات الاولى:

المستخلص: تم حساب حساسية الجرافين النقي (PG) والجرافين المطعم بالنتروجين (N - doped graphene) والجرافين المطعم بالالمنيوم (Al - doped graphene) لسلسلة من جزيئات الغازات الصغيرة وهي CO وCO2 وNH3 وNO وNO2 وSO2 باستعمال برنامج كاوسين 09 الذي يطبق نظرية الكثافة العملية (DFT) بدالة Perdew - Burke - Ernzerhof (PBE) ومجموعة الاساس 6 - 31G. وقد تم استقصاء تاثير التطعيم بواسطة تغيير تركيز ذرات التطعيم بنسبة 2.4 % (بمقدار ذرة واحدة من النتروجين او الالمنيوم في 42 ذرة مضيفة). اظهرت النتائج ان امتزاز CO وCO2 وNH3 وNO وNO2 وSO2 على سطح الجرافين النقي والجرافين المطعم بالنتروجين يكون امتزاز فيزيائي ضعيف وبطاقة امتزاز (Ead) تتراوح بين eV (0.115 - الى 0.640)، باستثناء امتزاز الغازات NO2 وSO2 على الجرافين النقي التي يكون امتزازها كيميائي قوي، في هذه الحالة، الجرافين النقي يكون محفز او منشط، وهذا يقترح امكانية استعمال الجرافين النقي كمحفز خالي من المعدن. كذلك، يكون امتزاز NO2 وSO2 على الجرافين المطعم بالالمنيوم امتزاز فيزيائي ضعيف وبطاقة امتزاز تتراوح بين eV (0.298 الى 0.611)، وبعبارة اخرى يمكن ان يستعمل الجرافين المطعم بالالمنيوم كمتحسس جيد لغازات NO2 وSO2. على اية حال، يكون امتزاز الغازات CO وCO2 وNH3 وNO على الجرافين المطعم بالالمنيوم امتزاز كيميائي قوي وبطاقة امتزاز اكبر من eV1، ونتيجة لهذا التفاعل القوي فان الجرافين المطعم بالالمنيوم يكون محفز او منشط، وهذا يقترح امكانية هذا الجرافين كمحفز. علاوة على ذلك، تكون فجوة الطاقة (Eg) مفتوحة وبطرق مختلفة للجرافين النقي والجرافين المطعم بالنتروجين والجرافين المطعم بالالمنيوم عند امتزاز الغازات CO وCO2 وNH3 وNO وNO2 وSO2. كذلك، فان الجرافين المطعم بالنتروجين الممتز بجزيئة غاز SO2 له القدرة على منح الكترون، لانه يحتاج الى طاقة صغيرة لازالة الكترون ليصبح ايون موجب. تظهر الدراسة امكانية تطبيق الجرافين النقي كمتحسس جيد لغازات CO وCO2 وNH3 وNO والجرافين المطعم بالنتروجين كمتحسس جيد لغازات CO وCO2 وNH3 وNO وNO2 وSO2. توضح نتائجنا ان الخصائص الالكترونية للجرافين يمكن ان تعدل (تطور) بتطعيمها بالنتروجين والالمنيوم والامتزاز بالغازات لتستعمل لتصميم متحسسات كيميائية، وبالتالي يمكن ان يستخدم الجرافين لبناء متحسسات لاكتشاف جزيئات مخصصة. | The sensitivity of pristine graphene (PG), nitrogen - doped graphene (N - doped graphene) and aluminum - doped graphene (Al - doped graphene) toward a series of small gas molecules CO, CO2, NH3, NO, NO2 and SO2 by using Gaussian 09 program which applies the density functional theory (DFT) with Perdew - Burke - Ernzerhof (PBE) functional and 6 - 31G basis set. The effect of doping was investigated by varying the concentration of doping atoms 2.4% (one atom of nitrogen or aluminum in 42 host atoms). The results show that the adsorptions of CO, CO2, NH3, NO, NO2 and SO2 on PG and N - doped graphene are weak physisorption with an adsorption energy (Ead) ranging from ( - 0.115 to 0.640) eV, except the adsorption of NO2 and SO2 on PG are a strong chemisorption, in this case, the PG could catalyse or activate, suggesting the possibility of PG as a metal - free catalyst. Furthermore, the adsorptions of NO2 and SO2 on Al - doped graphene are weak physisorption with a Ead ranging from (0.298 to 0.611) eV, otherwise Al - doped graphene could be a good sensor for NO2 and SO2. However, the adsorptions of CO, CO2, NH3 and NO on Al - doped graphene are a strong chemisorption with Ead larger than 1 eV, due to the strong interaction, Al - doped graphene could catalyse or activate, suggesting the possibility of Al - doped graphene as a catalyst. Moreover, the energy gap (Eg) of PG, N - doped graphene and Al - doped graphene is opened upon adsorption of CO, CO2, NH3, NO, NO2 and SO2 in various ways. Also, the N - doped graphene with SO2 gas molecule adsorption has the ability to donating an electron, it needs a small energy to remove an electron to become a cation. The study demonstrates the feasibility of PG to be a good sensor for CO, CO2, NH3 and NO and N - doped graphene could be a good sensor for CO, CO2, NH3, NO, NO2 and SO2. The results reveal the electronic properties of graphene which modified by nitrogen and aluminum doping and molecules adsorption, that could be used to design chemical sensors, and graphene could be used to build sensors for the detection of particular molecules

تحضير ودراسة الخواص البصرية والكهربائية للمتراكبات البوليورية النانوية المواصلة PANI - DBSA/ MWCNTs وتطبيقاتها في الخلايا الشمسية == Preparation and Study The Optical and Electrical Properties of Nanocomposite (PANI - DBSA / MWCNTs) and Application in Solar Cell

اسم المؤلف: هناء هاشم عناية

اسم المشرف: كريمة مجيد زيدان

الموضوع العام: علوم الفيزياء

السنة: 2017

الموضوع الدقيق: الفيزياء

الدرجة: ماجستير

الجامعة: جامعة البصرة - كلية العلوم

اللغة: الانكليزية

مكان الجامعة: البصرة

الصفحات الاولى:

المستخلص: The present thesis Conducts polymer (polyaniline) doped with Dodycyl Benzene Sulfonic Acid (DBSA) was prepared by chemical polymerization and with the help of ammonium persulphat (NH4)2S2O8 as oxidizing agent.Multi well carbon tubes MWNTs are ultrasonically treated with strong acide using a 3 : 1 mixture of concentrated H2SO4 and HNO3, producing carboxylic groups c - MWNTs .Nanocomposite conducting polymers PANIDBSA/ MWCNTs was prepared with adding different weight ratios (0%,1%,2%,3%,5%)(MWNCTs to PANI - DBSA). Accordingly, films of these nanocomposite polymer were prepared by spin coating technique .To study the optical properties, these films were deposited on glass, and on interdigitated finger electrode for the - electrical properties.The chemical structure of the prepared polymers PANI - DBSA, c - MWNCT and PANI - DBSA/MWCNTs are characterized by the FTIR spectra .The results indicated an appearance of functional group of doping with DBSA and MWNCTs changed to c - MWNCTs.The structure of preparation films are characterized by X - RAD diffraction .The results show crystalline peaks partial crystallinity of the PANI - DBSA/MWNCTs. The grain size of polymer was calculated by Scherrer relation.Morphologies and diameters of the nanocomposite were studied by Atom ic Force Microscope(AFM) and Scanning Electron Microscope (SEM). The average diameters of nanocomposite change between (81 - 118) nm and the roughness increased with increasing of MWNCTs in nanocomposite. Ology and the thickness were measured by Scanning Electron Microscope (SEM).The result shows the polymer covered MWNCT.The optical properties of preparation film were studied from absorbance spectra at wave - lengths of (300 - 1100 nm). The analyses of optical measurement shows direct transition with energy gap decreasing increases MWNCTs about(3.4 - 1.9) eV. The reflection spectrum is analysed to find same optical constant like extension coefficient and refraction coefficient.The electric conductivity was measured and it was found that the thin films correlate with the ohmic behaviour at voltage under 10V.The electricalconductivity increases as the ratios of MWNCTs increases in PANIDBSA/ MWNCTs nanocomposite from(6.17x10 - 3 S/cm ) at 0wt% to (1.12x10 - 1 ????/cm ) at 5wt% .The effect of temperature on the electric conductivity of all ratios of thenanocompositesare also studied. The resultindicated the activationenergy decrease as MWNCTs increase from 0.15 at (0wt %) to 0.05 at (5wt %).In electronic applications of nanocomposite conducting polymers solar cell,two kinds of solar cells (ITO/TiO2/PANI - DBSA/MWCNTs/C/ITO ) and (ITO/TiO2/PANI - DBSA/MWCNTs/dye/C/ITO) were fabricated. The currentvoltage characteristics are measured at light source 100mw/cm2.The solar cell parameter like open circuit voltage VOC ,short circuit current JSC, shunt resistance RSh, series resistance RS, full factor FF, and efficiency η, are calculated. The efficiency of solar cell at different ratios of MWNCTs in PANI - DBSA/MWNCT were calculated. The result indicated that the efficiency increased as MWNCTs increase. The efficiency of solar cells also increases with adding dye.