Show: 25 50 75 100 Results

Search results: 50 out of 314

دراسة اداء جهاز مرشح الليف البصري ذو الحزمة الضيقة باستخدام محززات براك لليف البصري == Study the Performance of Implemented Narrow Band Optical Fiber Filter Using FBGs

Author name: مناف صالح مجيد
General topic: Laser Science
Specific topic: Laser Applications in Physics
Degree: Master
University: University of Baghdad - Laser Institute For Postgraduate Studies
Language: English
University location: Baghdad
First pages:

تاثير ليزر ثنائي اوكسيد الكربون المجزئ على خشونة السطح وارتباط زركونيوم السيراميك مع الاسمنت الراتنج == Effect of Fractional CO2 Laser on the Surface Roughness and Bonding of Zirconium Ceramic to Resin Cement

Author name: لمى ابراهيم محمد علي
Supervisor name: حسين على جواد
General topic: Laser Science
Specific topic: Laser Applications in Medicine - Dentistry
Degree: Master
University: University of Baghdad - Laser Institute For Postgraduate Studies
Language: English
University location: Baghdad
First pages:

توليد الموجه المثالية باستخدام محزز براغ الليفي == Soliton Generation in Fiber BraggGrating

Author name: ليث طارق محمد
Supervisor name: تحرير صفاء منصور
General topic: Laser Science
Specific topic: Laser Applications in Electronics and Communications Engineering
Degree: Master
University: University of Baghdad - Laser Institute For Postgraduate Studies
Language: English
University location: Baghdad
First pages:

تنفيذ البوابة اكس اور بصريا بالكامل لمنظومات الاتصالات البصرية == Implementation of All Optical Exclusive - OR Gate for Optical Communication Systems

Author name: ياسمين سلمان كاظم
General topic: Laser Science
Specific topic: Laser Applications in Electronics and Communications Engineering
Degree: Master
University: University of Baghdad - Laser Institute For Postgraduate Studies
Language: English
University location: Baghdad
First pages:
Abstract: One of the most important techniques used to realize logic gates in optical networks is by all - optical signal processing.The most two important problems of electronic signal processing are high propagation loss of electronic signals and the high cost of the high speed electronics. Accordingly, these reasons led to converting to optical domain at higher frequencies (≥ 10 ????????/????) .The goal of this work is to implement all optical logic gates specifically exclusive - OR gate. Exclusive - OR gate have an important role in data encryption, parity checking, data encoding, bit pattern generation and matching, addressing, header recognition and many more applications. In this work an all - optical exclusive - OR logic function was achieved by a simulation software and implementing an experiment.In the simulation work, the exclusive - OR function was implemental by using a highly nonlinear fiber with a fiber nonlinear coefficient of 9.1 ????−1????????−1 , 0.135 km length non - degenerate with four wave mixing process and a NRZ - DPSK 10 GB/s signals.Experimentally the exclusive - OR function was implemented by using a highly non fiber with a fiber nonlinear coefficient of 10 ????−1????????−1and a 1 km length with bidirectional degenerate four wave mixing process. The optical signals that were used for the operation of the exclusive - OR function were NRZ - DPSK 40 GB/s signals. Results showed an exclusive - OR function associated with clear eye diagrams. In addition to that, exclusive - NOR function was also obtained experimentally in addition of these four maxterms (A + B, ????̅+ B, A + ???? ̅ and ????̅ +???? ̅ ).

تاثير ليزر النودميوم ياك وبيبتيدات الفوسفات الجبنية - فوسفات الكالسيوم الغير متبلرة مع الفلوريد على ازالة تمعدن مينا الاسنان في دراسة مختبرية == The Effect of Nd : YAG Laser and Casein - Phosphor - Peptide - Amorphous Calcium Phosphate with Fluoride on Dental Enamel De - mineralization : In vitro study

Author name: هبة عصام عبد الوهاب
Supervisor name: علي شكر محمود
General topic: Laser Science
Specific topic: Laser Applications in Medicine - Dentistry
Degree: Master
University: University of Baghdad - Laser Institute For Postgraduate Studies
Language: English
University location: Baghdad
First pages:
Abstract: New approaches for caries prevention by using lasers effect combined remineralizing agent providing calcium and phosphate in addition to flouride for increasing the tooth mineral resistance needed. The aim of this study is to evaluate a new treatment modality to decrease dental enamel dissolution via combing the effect of pulsed Nd : YAG laser (1064 nm) and MI plus paste (CPP - ACP containing sodium fluoride ) regarding the tooth pulp chamber temperature elevation, calcium concentration dissolute from enamel surfaces and the dental enamel absorption of methylene blue stain by assessing (R,G,B)values .Eighty human permanent premolar were used in this study, sixty of them were randomly divided into six groups of 10 specimens. The negative control group A received no treatment, and the positive control group B the MI plus paste was applied without laser irradiation. For the groups C, D, E and F the pulsed Nd : YAG (1064 nm) laser was used in two energy settings. The lower laser dose setting at (0.6W, 60 mJ )without and with the MI plus paste for the groups C and D respectively and the higher laser energy setting at (1.7W, 170 mJ )with and without the MI plus paste for the groups E and F respectively.Twenty teeth were used to asses s the temperature elevation during irradiation with laser using a K - type thermocouple at 37 ± 0.5 ̊C, ten teeth exposed to the lower laser energy settings and ten for the higher laser energy settings.A circular window (4 mm radius) marked area on buccal surfaces of the 60 samples after they had been coated with three layer of nail varnish to exposed to the Nd : YAG laser irradiation, and then the samples incubated in 3ml acidic solution of acetate buffer of (0.1M/L) with a pH value of 4.5 for 48 hours . The acidly etched samples removed from the acidic solution after they had been washed from acid they immersed in a 2% solution of methylene blue dye to measure the (R,G,B) values to indicted the affinity of sample surfaces for absorbing methylene blue stain that indicate the surface demineralization . Results of temperature test +showed that the maximum temperature increases for group E (4.7 Co) was very high significant difference (p<0.05) over that of groups C (2.5 Co).The atomic absorption photometry test results showed that groups C, and D were statistically different compared to the groups A and B (p<0.001) in the reduction of calcium dissolution, with a reduction percentage for groups C and D of 25.7% and 33.34% respectively compared to group A, with 21.75% and 29.8 % for groups C and D respectively in comparison to group B. While Groups E and F shown nonsignificant reduction in calcium dissolution compared to control groups.The (R,G,B)s value test showed that groups C and D having lower affinity to absorb methylene blue stain, and they are statically significant different compared to the groups A and B .while groups E and F showing a higher affinity to absorb methylene blue stain compared to control groups. In conclusion the both laser irradiation settings energy (60mJ, 0.6 W,0.12 J/cm2),(170mJ,1.7W,0.34J/cm2) are safe for the vitality of the dental pulp, and when both settings combined with the Phosphor - Peptide - Amorphous Calcium Phosphate with Fluoride ,the results showing significant reduction of dental enamel de - mineralization and lower affinity for methylene blue absorption that although indicate increasing dental enamel resistance to demineralization for the groups of (60mJ, 0.6 W,0.12 J/cm2) laser irradiation settings.

تاثير المعلمات المختلفة لليزر الليف على تعرية الصبغ البوليمري من على سطح سبيكة الالمنيوم نوع 5005A == Effect of Different Fiber Laser Parameters on Stripping of Polymer Paint from Surface of 5005A Aluminum Alloy

Author name: هالة عبود جاسم
General topic: Laser Science
Specific topic: Laser Applications in Mechanical Engineering
Degree: Master
University: University of Baghdad - Laser Institute For Postgraduate Studies
Language: English
University location: Baghdad
First pages:
Abstract: This study provides details of the use of laser as an alternative method to the conventional ones to remove (20) μm thickness of polyester paint from EN AW - 5005A Aluminum alloy, the laser paint stripping process performed by ytterbium fiber laser with a wavelength (1064) nm .Sets of experiments curried out in order to reach to the most suitable parameters for the process, at the first set different levels of energies used from 0.0425 mJ to 1.12 mJ, nine lines of holes accomplished by laser. The holes diameters and the depth at each energy measured in this experiment. At two different pulse repetition rates (20, 50) KHz two sets of experiments done. At the first set the effect of laser energy (0.1565, 0.73, 1.12)mJ also the overlap percent (25%, 50%, 75%) have been studied at five number of passes, the parameters of the process settled by the overlap equations, the effect of the overlap percent on the total time of machining and the material removal rate at different levels of energy also investigated, it’s found that the best energy to work with is 0.1565mJ with one and two passes.The second set of experiments done at 0.1565mJ with a wider range of overlap percent from 25% to 75% increase by five. The removal depth and the behavior of surface roughness determined by Focus Variation Microscopy (FVM) also Scanning Electron Microscope used to analyze the radiated area. It’s found that the best results obtained at 50 % overlap when the laser passes one time on the material.Laser Induced Breakdown Spectrometer (LIBS) used as a method for monitoring and controlling the paint stripping process in order to accomplish the process and ablate only the paint layer without ablating the substrate, for the paint and the substrate (LIBS) spectrum obtained and used to distinguish between the paint layer and the Aluminum substrate.

قياس وتحليل الخسائر لموجات الموجع ذوات الفتحة المصنعة من سليكون على عازل == Measurements and Analysis of The Losses for Fabricated SOI Slot Waveguides

Author name: ميثم نعيم صالح
Supervisor name: مازن مانوئيل الياس
General topic: Laser Science
Specific topic: Laser Applications in Electronics and Communications Engineering
Degree: Doctorate
University: University of Baghdad - Laser Institute For Postgraduate Studies
Language: English
University location: Baghdad
First pages:
Abstract: An interesting silicon photonics component is the slot waveguide. The discontinuity of the normal component of the displacement vector can be used to affect guiding of the majority of the electric field energy in a narrow low index gap when the field is polarized parallel to the silicon surface, that is, perpendicular to the silicon confining walls. By infiltrating nonlinear material into such a gap, one can simultaneously confine electric and optical fields achieving a high efficient optical modulation or switching that is becoming more desirable on optical communication. An array of 200 Silicon - on - Insulator (SOI) slot waveguide devices of varying slot widths, ribs widths, taper lengths and slot lengths are fabricated in each cell of a wafer fabricated at a commercial foundry. The cells are cleaved into individual chips after fabrication. Some chips are coated with thin films of polymers that fully infiltrated the slots. Measurements that consisted on spectral loss are made on the grating coupler waveguide devices of both coated and uncoated chips. Individual devices exhibited insertion losses varying from several dB up to values so great that the response is below the noise floor of the optical spectrum analyzer employed as a receiver. The chips that failed in the transmission test are primarily uncoated ones. Nominally identical devices on different chips exhibited nominally identical behavior. A commercial software program is used to simulate each of the structures that is included in the 200 devices test. The simulations are seen to show a degree of qualitative agreement with the experimental results. Comparison of the experimental measurements and the simulation results indicates that the loss inherent in a slot waveguide is quite low. Near loss free couplers from ridges to slots are achievable in case of coated devices, whereas the situation is different in case of uncoateddevices where a lot of energy is dissipated through the substrate. Use of a surface roughness model indicates that the excess loss that slots exhibit with respect to a ridge mode counterpart arise almost solely from surface scattering off the surface roughness. The increased loss in the case of the slot guide arises from the higher electromagnetic energy density at the surface of the guide due to the electric field discontinuity that is employed as a guidance mechanism in slot modes in contradistinction to ridge modes that are index - guided. Conclusions include some speculation as to the limits on the loss that can be achieved by variation the design of slot guides without any improvement in surface roughness over what is now available with fabrication in commercial foundries.

محزز الليف البصري نوع براغ لتحسس الحرارة والضغط == FIBER BRAGG GRATING FOR TEMPERATURE AND PRESSURE SENSING

Author name: فهد محمد عبد الحسين
Supervisor name: تحرير صفاء منصور
General topic: Laser Science
Specific topic: Laser Applications in Electronics and Communications Engineering
Degree: Master
University: University of Baghdad - Laser Institute For Postgraduate Studies
Language: English
University location: Baghdad
First pages:
Abstract: Nowadays, the modern trends in optical sensing are to build simultaneous measurements sensors. In this work two schemes for simultaneous measurements sensors are presented. The first one is with dual FBGs peaks. Every FBG acts as sensing head. The first peak was used for temperature sensing and the obtained sensitivity is 10 pm/˚C and the second peak was used for temperature and pressure measurements with sensitivities 9.2 pm/˚C and 67 pm/ bar for temperature and pressure respectively.The other scheme consists of two sensing heads fabricated in the lab. The first sensing head is the Fabry - Perot interferometer which was used for load and strain measurements by controlling the size of its cavity reached to minimum value in micro scale (30). The sensitivity was increased to 4.07 nm/ N and 5.11 pm/ μɛ for load and strain respectively. This sensitivity for load is the highest that was recorded by micro cavity where previous works were reached to 1.37 nm/N. The second sensing head made by inscribing Bragg gratings inside the core of All Solid Photonic Band - Gap fiber toenhance its sensitivity that reached to 13.7 pm/˚C and 0.7 pm/μɛ for temperature and strain respectively which is more sensitive than previous works of our group in the institute that reached to 10 pm/˚C and 0.66 pm/μɛ for temperature and strain respectively. The obtained temperature sensitivity for the Bragg gratings is higher than previous work for Bragg gratings inscribed on All Solid Photonic Band - Gap Fiber where it was 12.04 pm/˚C.Strain sensitivities were almost the same.

التحقق عمليا من بروتوكول البينغ بونغ

Author name: علاء جبار جمعة
Supervisor name: شيلان خسرو توفيق
General topic: Laser Science
Specific topic: Laser Applications in Electronics and Communications Engineering
Degree: Master
University: University of Baghdad - Laser Institute For Postgraduate Studies
Language: English
University location: Baghdad
First pages:
Abstract: Quantum cryptography uses basic laws of quantum physics to guarantee secure key exchange. The key can be used with unprecedented confidence in any classic cryptographic protocol, where it increases the security to the maximum achievable value. The goal of this work is to encrypt the message directly without need to generate the secure key by using the modified Ping - Pong Protocol. A quantum cryptography system based on Modified Ping - Pong Protocol was designed and implemented for the first time. A polarization - entangled photons were generated by a source using PPKTP crystal inside a polarization Sagnac interferometer at telecom wavelength 1550 nm and a fiber length of 15 Km. In this experiment, Bob prepares entangled photons, sends one photon to Alice by optical fiber to perform one out of four operators according to the message. The modulated photon is sent back to Bob. Then the Bell’s state measurement is applied to extract the message according to the Alice’s coding. The HOM - dip of the two - photon interference was verified to guarantee perfect system performance. The final results showed the switching between the Bell’s states, |????+⟩ and |????−⟩ as the phase of the phase modulator was changed by Alice achieving an acceptable coincidence count of about 625 counts per 30s. These results proves also two photon interference needed to test Bell’s enquality.

تحسين خصائص سطح سبيكة الالمنيوم باستخدام الاكساء بالليزر بانابيب كاربون نانوية مزدوجة الجدار ونابيب كاربون نانوية متعددة الجدار == Enhancement of Al 6061 - T6 Alloy Surface Properties using Laser Cladding with DWCNTs and MWCNTs

Author name: حسنين مجيد حسين
General topic: Laser Science
Specific topic: Laser Applications in Mechanical Engineering
Degree: Master
University: University of Baghdad - Laser Institute For Postgraduate Studies
Language: English
University location: Baghdad
First pages:
Abstract: Industrial applications of nanomaterial in particular carbon nanotubes (CNTs) have increased from various viewpoints, such as, high performance, energy saving, cost saving, and environmental concerns. Laser cladding technique has been used successfully to modify the surface properties of materials, i.e., improving their wear and corrosion resistance. This work involves cladding aluminum alloy (Al 6061 T6) with different types of carbon nanotubes (multi - walled carbon nanotubes (MWCNTs) and double walledcarbon nanotubes (DWCNTs)) by an automated pulsed Nd : YAG laser. This was achieved by controlling selected cladding parameters whic h are laser power, pulse duration, and working frequency. The experimental investigation included microhardness, energy dispersive X - ray, corrosion resistance and microstructure topography by scanning electron microscope. At the beginning, fifteen cladded samples divided into three groups were investigated to choose the best laserparameters for the process to have almost the best homogeneous clad layer. Group one; five levels of peak power (2.7, 2.9, 3.1, 3.3, and 3.5) kW respectively where varied versus fixed pulse duration of 16 ms, working frequency of 1.5 Hz, and scanning speed of 0.5mm/s. Group two; five levels of pulse duration (12, 14, 16, 18 and 20) ms respectively where varied versus fixed peak power of 3.1 kW, working frequency of 1.5Hz, and scanning speed of 0.5mm/s. Group three; five levels of working frequency of (1.1, 1.3, 1.5, 1.7, and 1.9) Hz respectively where varied versus fixed peak power of 3.1 kW, pulse duration of 16 ms and scanning speed of 0.5 mm/s. The investigation shows that the optimum estimated laser parameters for achieving the best results at spot diameter of 3 mm were (peak power of 3.1 kW, pulse duration of 16 ms (3 ms as preheating and 13 ms as the main action time of the pulse) and working frequency of 1.5 Hz.The executed process in this work was computationally modeled using commercial multiphysics finite element analysis (FEA) software package ANSYS® Release 11 to simulating the virtual environment of laser cladding process to determine the temperature distribution in three - dimensional (3D) analysis. Results indicated that laser cladding of Al 6061 T6 using DWCNTs enhanced three of the most important of surface properties which are hardness, abrasive wear resistance and corrosion resistance more than did the MWCNTs. The distribution of the MWCNTs on the surface of Al 6061 T6 is better than that for the DWCNTs but its penetration is less. Theoretical results show that the diffusion played an important role in the cladding process.

الليف البلوري الفوتوني لاستشعار المجال المغناطيسي == Photonic crystal fiber magnetic sensor

Author name: احمد عدنان محمد
Supervisor name: عبد الهادي مطشر الجنابي
General topic: Laser Science
Specific topic: Laser Applications in Electronics and Communications Engineering
Degree: Master
University: University of Baghdad - Laser Institute For Postgraduate Studies
Language: English
University location: Baghdad
First pages:
Abstract: Photonic crystal fiber (PCF) is widely used for sensing applications. In this work, magnetic sensor based on solid core - PCFs for sensing magnetic field was presented. The general structure of the sensor applied is by splicing short lengths of PCF (LMA - 10) with conventional single mode fiber (SMF - 28) in one side and using free space connector from other side. A laser diode with different wavelengths (850, 1060 and 1300 nm) has been used as a light source, where a high sensitive optical spectrum analyzer (OSA) was used to monitor and record the transmitted/reflected spectra.The present work demonstrates the results of the infiltration of the air holes for the PCFs by fluids instead of air. For magnetic sensing, the magnetic fluids being used were prepared and standard ????????3????4 to infiltrate the air holes for the solid core PCF (LMA - 10) which leads to change in the effective refractive index of the PCF, which in turn affects the transmission of the laser inside the PCF due to the value of the refractive indices of the magnetic fluids. The experiments show that the power of transmissionspectrum of the laser had decreased after infiltration without any change in central wavelength of the laser diode the reason is that after PCF air holes infiltration, the effective refractive index has been changed but still within total internal reflectionwhich leads to loss of some fundamental modes, in turn leads to decrease the power of transmission spectrum. The decrease of the transmitted power in the case of standard has been higher than it in the case of prepared ????????3????4 because of the differencein concentration between standard and prepared magnetic fluids. The power of transmission spectrum after PCF infiltration will be increased with increasing magnetic field. Higher sensitivity has been obtained that reached 5.809 nW/mT which consideredhigher than previously published works on PCF magnetic sensors.

التحقق من تاثير عدم استقرارية بلاتو - رايلي في عملية سحب ليف شبه المواد انديوم - بوليمر == Investigation of the influence of the Plateau - Rayleigh instability in fibre drawn indium - PMMA metamaterial

Author name: احمد عبد الكريم علي
Supervisor name: عبد الهادي مطشر الجنابي
General topic: Laser Science
Specific topic: Laser Applications in Electronics and Communications Engineering
Degree: Doctorate
University: University of Baghdad - Laser Institute For Postgraduate Studies
Language: English
University location: Baghdad
First pages:
Abstract: Metamaterial is a synthetic composite material with a structure such that it exhibits properties not usually found in natural materials. Fibre drawing method has been used in producing Poly - methyl methacrylate (PMMA) - indium wires metamaterials. PMMA and indium are having relatively the same glass transition temperature making them suitable for co - drawing. The fiber filaments must be drawn to smaller diameters to shift the metamaterials response to higher frequency. At these dimensions the metal filaments inside the fiber become unstable and break - up at random intervals. This instability is due to a phenomenon known as the Plateau - Rayleigh InstabilityWell known Tomotika model for the growth in the varicosity in the surface of fluid extended inside another fluid was modified to describe the fluctuations (instability) of inner core diameter for metamaterials drawing inside radiative furnace. Modified Tomotika model was used to investigate the instability growth of the indium wire diameter produced by co - drawing of indium metal embedded in a PMMA polymer.The critical parameter for the wire breaks is the wavelength of perturbations. A MATLAB model was used to describe a small drawing ratio (neglecting the wavelength of fluctuations effect). The experimental and modeling results are almost match when a very small temperature variation occurred. So the observed fluctuations in diameter can be reconciled with the Plateau - Rayleigh instability.For larger fluctuations (large drawing ratio) the wavelength of fluctuations was analyzed and sequential breakup on different length scales was observed. We infer limits to wire dimensions that can beachieved using the chosen material system and identify a path for extending drawing methods to fabricate smaller wires.Finally, simulation for deep subwavelength wave propagation inside wire metamaterials depending on the unit cell manipulation was performed. CST microwave studio software had been used to simulate wave propagation inside linear and 90o corner waveguide as well as equal arms beam splitter (50/50). It’s applicable to waveguiding 40cm wavelength in about 2.4 cm waveguide.

التلوين المستحث بليزر الليف للتيتانيوم العالي النقاء == Fiber Laser Induced Colouration of High Purity Titanium

Author name: نور ياسر حسون حمادي
General topic: Laser Science
Specific topic: Laser Applications in Mechanical Engineering
Degree: Master
University: University of Baghdad - Laser Institute For Postgraduate Studies
Language: English
University location: Baghdad
First pages:

التقييم السريري لالتام الانسجة للمابس السنية المنزوعة المشععة بليز الدايود 940 نانومتر == Clinical Assessment of The Tissue Healing of Extraction Socket Irradiated with 940 nm Diode Laser

Author name: ندى حسين حمودي
Supervisor name: علي شكر محمود
General topic: Laser Science
Specific topic: Laser Applications in Medicine - Dentistry
Degree: Master
University: University of Baghdad - Laser Institute For Postgraduate Studies
Language: English
University location: Baghdad
First pages:

دراسة تجريبية للحيود الحراري في صبغات مختلفة == Experimental Study of Thermal Self - Defocusing in Different Dyes

Author name: عمار محمد طعيمة
Supervisor name: مازن مانوئيل الياس
General topic: Laser Science
Specific topic: Laser Applications in Physics
Degree: Doctorate
University: University of Baghdad - Laser Institute For Postgraduate Studies
Language: English
University location: Baghdad
First pages:
Abstract: This thesis discusses the effect of three factors on self defocusing technique used to measure the nonlinear optical properties of two solutions, the first one is safranin O dissolved in ethanol (SOE), and the second one is diphenylecarbazone dissolved in chloroform (DCC). These factors are the intensity of laser, the concentration of the solution and the effect of the temperature on the solutions.After providing the necessary solution and equipment to complete the designed experiment, an appropriate model of nonlinear system was chosen to extract the diffraction rings contains the following parts : (Diode Laser, Attenuator, Mirrors, Beam Splitter, Lens, CCD Camera, Laser Power Meter and PC) In this work the maximum change and the thermo - optical coefficient for the nonlinear refractive index as well as the nonlinear refractive index were measured, for the two different solutions (SOE & DCC) including three ratios and grains for each one. The measurements were performed using diode laser at and variable intensity (0.5 - 22) and the laser beam was focused on glass cuvette which has a thickness of through a lens with a focal length of .From this work it was found that increasing the laser intensity leads to increase the number of diffraction rings, the nonlinear refractive index and the maximum change of the nonlinear refractive index, also it was found that increasing the concentration of the solutions leads to increase the nonlinear refractive index as well as increasing the maximum change of the refractive index.Also it was found that increasing the temperature of the solution at certain intensity and concentration the obtained results for the thermooptical coefficient , and the nonlinear refractive index are found to be of the order of and at 298, 303 and 308K respectively for SOE solution, and and at 298, 303 and 308K respectively for DCC solution, in which all the thermooptical coefficient and the nonlinear refractive index are deceased.

لحام ليزر الاندي ياك لمعادن غير متشابهة تيتانيوم رتبة 2 مع سبيكة المنيوم - O3105 == Dissimilar Nd : YAG Laser Welding of Grade 2 Titanium to 3105 - O Aluminum Alloy

Author name: عبير احمد شهاب العبيدي
General topic: Laser Science
Specific topic: Laser Applications in Mechanical Engineering
Degree: Doctorate
University: University of Baghdad - Laser Institute For Postgraduate Studies
Language: English
University location: Baghdad
First pages:
Abstract: التيتانيوم والالمنيوم مواد تلقى اهتمام تقني في الصناعات الالية والفضائية والمتحسس الذكي.التحديات التي تواجه لحامهم هي نتيجة للاختلاف الكبير في المواصفات الثرموفيزيائية والميكانيكية, اضافة الى الذوبانية المحدودة لكل معدن في الاخر,لذلك لحامهم باستعمال الليزرسيقلل تكوين الا طوار المعدنية الضارة لما كانت منطقة اللحام نفسها ضيقة .في هذا العمل قدم شكل خاص من اللحام الليزري النقطي لربط تيتانيوم رتبة 2 تراكبيا مع سبيكة المنيوم 3105 - O باسماك 1,0.5 ملم على التوالي, من خلال لحام درز دائري, لبق التصميم يستعمل نبضات ليزر متعاقبة ادت الى لحام شبيه للحام الليزري النقطي .لهذه الدراسة كانت معاملات لحام الليزر كالاتي : طاقة النبضة 11جول, مدة النبضة 6 ملي ثانية, تردد النبض 20هرتز,تدفق غاز الاركون 20 لتر/دقيقة وسرعة اللحام (4 - 6.67) ملم/ثانية.لقد لوحظ ان تاثيرسرعة اللحام كان الاقوى على الحرارة الداخلة لمنطقة اللحام حيث سرعة لحام 4 ملم /ثا (76%عامل تداخل النبضات), قد ادت الى افضل امتصاص لطاقة الليزر واكثر تجانس وعرض للمساحة المنصهرة عند منطقة تداخل ,Ti - Alلذلك تم الحصول على 70MPa مقاومة وصلة اللحام. اظهر فحص منطقة وصلة اللحام باستخدام المجهر الماسح الالكتروني SEM, مقياس تشتت طاقة الاشعة السينية EDS ومقياس انحراف الاشعة السينية,XRD تكون الا طوار المعدنية الضارة. المنطقة المنصهرة للتيتانيوم قرب منطقة تداخل Ti - Alضمت طور.Ti3Al الشقوق لوحظت في منطقة الالمنيوم المنصهرة قرب منطقة التداخل ,Ti - Alنتيجة الانحدار العالي في الخواص الميكانيكية والثرموفيزيائية. من اجل التقليل من تكون الا طوار المعدنية الضارة وتخفيف الانحدار العالي في الخواص . الثرموفيزيائية والميكانيكية, اربعة انواع مختلفة من الحشوات المعدنية (Al - 5Si, Al - 12Si - 2.5Mg, pure Nb and Al - 0.2Sc - 0.36Zr) مع ثلاثة اسماك مختلفة لكل حشوة قد حضرت في هذا العمل. حشوة Al - 5Si كان لها تاثير ايجابي على مقاومة وصلة اللحام حيث ان Siقلل التاثير الضار للاطوار المعدنية الضارة من خلال تعويض ذرات Al في Ti3Al لذلك فان مقاومة الوصلةزادت الى MPa80بدل MPa70.حشوة Al - 12Si - 2.5Mg قد حسنت مقاومة الوصلة الىMPa87 متجاوزة بذلك مقاومة القصMPa82 لترابط المعدن الاساس Al. نتيجة درجة اانصهاره العالية, حشوة النيبيوم النقي Nb منعت لحام صفيحة Al السفلى, لذلك هذه الحشوة كانت غيرمناسبة للا ستعمال وفق شروط اللحام لهذا العمل. لقد كان للحشوة الجديدة Al - 0.2Sc - 0.36Zr التي استعملت لاول مرة من خلال هذا العمل تاثير ايجابي جدا على قوة ترابط وصلة اللحام MPa103 حيث ان الكسر حدث من المعدن الاساس Al وليس من الوصلةخلال عملية الاختبار. بالمقارنة مع مقاومة التاكل لمعدن التيتانيوم الاساس, اظهرت الوصلات بدون استعمال حشوة وباستعمال حشوة Al - 0.2Sc - 0.36Zr نقصان بمعدل التاكل ب %51 و%72 بالتعاقب بينما اظهرت الوصلات باستعمال حشوات Al - 5Si,Al - 12Si - 2.5Mg زيادة بمعدل التاكل ب % 80 و%68 بالتعاقب. | Materials titanium and aluminum are of technological interest in automotive, aerospace and smart sensor industries. The challenges for welding them result from the large difference in thermophysical and mechanical properties, besides limited solubility of each metal in other. Thus welding them using laser, will reduce intermetallic phases (IMP) formation to acceptable limits, since the weld itself is narrow.In the present work a special form of laser spot welding is introduced to joint overlapped titanium Ti Grade 2 to 3105 - O aluminum alloy, with 1 and 0.5 mm thicknesses respectively. A welding tactile seam tracking design using following pulses that result to a circular seam, leads to spot like shape laser welding. For this study, laser welding parameters were : pulse energy 11 J; pulse duration 6ms; pulse frequency 20Hz; argon gas flow rate 20 l/m and welding speed (4 - 6.7) mm/s. Welding speed was observed to have the strongest effect on heat input, where 4 mm/s (76% overlapping) speed has led to better energy absorption and wider more uniform melted area at Ti - Al interface, thus 70 MPa joint strength was obtained. Examination of the joint region using scanning electron microscopy (SEM), energy dispersive X - ray spectrometry (EDS) and X - ray diffraction (XRD) showed the formation of different IMP in the Ti - Al welding zone. Ti fusion zone (FZ) near the interface was mainly containing Ti3Al. Crakes were observed in Al (FZ) near the interface as a result of mechanical and thermo physical properties gradient. Inorder to reduce IMP formation and relaxes the high gradient in thermophysical and mechanical properties in the welding zone, four fillers metals (Al - 5Si, Al - 12Si - 2.5Mg, pure Nb and Al - 0.2Sc - 0.36Zr), with three different thicknesses for each filler, were prepared. Al - 5Si filler has positive effect on the joint strength where Si has reduced the IMP harmful effect via replacing Al atoms substitutionaly in TiAl3 at the interface, thus joint strength was increased to 80MPa instead of 70MPa. Al - 12Si - 2.5Mg filler has improved the joint strength to 87MPa where the shear strength of Al base metal of 82MPa was exceeded. Due to its high melting point pure Nb filler prevented penetration of bottom Al sheet, thus it was unsuitable to use for the present work conditions. A new Al - 0.2Sc - 0.36Zr filler was used for the first time in the present work and has very positive impact to the joint strength 103MPa, where the joint has fractured from Al base metal. In comparison to the corrosion rate of Ti base metal, joints without using filler and with the new Al - 0.2Sc - 0.36Zr filler metal, have decreased the corrosion rate by 51% and 72% respectively, while joints with Al - 5Si and Al - 12Si - 2.5Mg filler metals, have increased the corrosion rate by 68% and 80% respectively.

ليزر الدايود (970 نانوميتر) في كشف الزرعة السنية في المرحلة الثانية مقارنة مع الطريقة الجراحية التقليدية في الجسم الحي == 970 nm Diode Laser In Second Stage Dental Implant Exposure Comparative Study With Conventional Surgical Method .In vivo Study

Author name: سلا علي حمدي
Supervisor name: حسين علي جواد
General topic: Laser Science
Specific topic: Laser Applications in Medicine - Dentistry
Degree: Master
University: University of Baghdad - Laser Institute For Postgraduate Studies
Language: Arabic
University location: Baghdad
First pages:
Abstract: تعد زراعة الاسنان التطور الاكبر لطب الاسنان اذ انها تعالج فقدان الاسنان دون التاثيرعلى الاسنان الموجودة لتعويض السن المفقود.تقسم عملية الزرع بشكل عام الى مرحلتين : المرحلة الاولى هي العملية التي يتم فيهاغرس الزرعة السنية داخل عظم الفك وتركها مطمورة تحت اللثة لمدة 3 - 6 اشهر لحين اكتمال التحام العظم بالزرعة والمرحلة الثانية وتشمل كشف الزرعة المطمورة وازالة نسيج اللثة جراحيا .الاهداف تقييم كفاءة القطع الجراحي للدايود ليزر ذو الطول الموجي 970نانوميتر ومقارنته مع القطع الجراحي التقليدي باستخدام الشفرة في عملية كشف الزراعة السنية اثناء المرحلة الثانية من عملية الزراعة من خلال كمية المخدر الموضعي المطلوبة ,وقف النزيف,الوقت المستغرق لاجراء العملية ,الم ما بعد الجراحة واخيرا الوقت المناسب لاخذ الطبعة من اجل اكمال الخطوات المختبرية لصناعة الاسنان المفقودة. اجريت هذه الدراسة في قسم زراعة الاسنان /مركزالعلوية التخصصي لطب الاسنان للفترة من كانون الاول للعام 2013 لغاية تشرين الاول 2014 ، 50 مريض يحتاجون الى كشف الزرعة المطمورة قسموا الى مجموعتين المجموعة الاولى والتي تىشمل 24مريض تم استخدام الشفرة الجراحية رقم15والمخدر الموضعي تقنية التسرب والمجموعة الثانية المتكونة من26 مريض تم كشف الزرعة باستخدام ليزر الدايود (سيرو ليزر ادفانس,سرونا ,المانيا) وبقوة مقدارها 3واط في الوضع المستمر وبتماس مع نهاية الفايبر قياس320مايكروميتروالمخدر الموضوع بتقنية البخ.كفاءة الليزر كانت عالية في قطع نسيج اللثة وبالمقارنة بين المجموعتين كان هناك فرق معنوي احصائي عالي في كمية المخدر الموضعي المطلوبة وطريقة التخدير ,متوسط الزمن المستغرق لاجراء العملية بين المجموعتين, الالم ما بعد العملية واخيرا الوقت المناسب لاخذ الطبعة لصالح مجموعة الليزر.استخدام 970 نانوميتر وبقوة 3واط دايود ليزر في كشف الزرعة المطمورة له فوائد عديدةمنها عدم الحاجة لاستخدام التخدير بتقنية التسرب,راحة الطبيب والمرض في ان واحد من حيث الوقت المستغرق وسهولة التطبيق وعدم شعور المريض بالالم وامكانية اخذ الطبعة في وقت مبكر حيث يمكن ان يتم ذلك بعد عملية الليزر مباشرة . | Following the placement of a dental implant and its integration into the osseous substrate, the current method of treatment is to surgically uncover the implant, wait for the tissue to heal, and then proceed with impressions and fabrication of the restoration. The second - stage surgery of submerged implants can be performed with a scalpel or by laser . This prospective study was designed to assess dental implant uncovering by 970 nm diode laser and to compare its performance with traditional cold scalpel surgery. Fifty patients with a completely osseointegrated implants participated in this study. Patients were divided into two groups. For the study group, second - stage implant surgery was done with a 970 nm diode laser in a 3W power . For the control group, the implants were exposed with a surgical blade. Certain parameters were used for evaluation of the two techniques. The use of the diode laser reduce the need for injected local anesthesia; there was a significant difference between the two groups regarding the need for anesthesia , duration of surgery, postoperative pain, time for healing and taking the impression(P < 0.001). The 970 nm with 3W diode laser can be used effectively for second - stage implant surgery, providing both the dentist and the patient with additional advantages over the conventional methods used for implant exposure .Laser cuts tissue precisely without infiltrative anesthesia and with excellent homeostasis . Because of lower amount of tissue destruction with the laser surgery the gingival contours seem tobe stable after laser implant recovery procedure . impressions can be madeimmediately and assuredly with no change in the emergenceprofile by any tissue shrinkage or recession.

الكشف عن البخار الكيميائي بحساسية عالية المستند على مقياس التداخل لليف البلوري الفوتوني == Chemical vapor detection with high sensitivity based on Photonic crystal fiber interferometer

Author name: رواء كاظم زرزور
Supervisor name: حنان جعفر طاهر
General topic: Laser Science
Specific topic: Laser Applications in Physics
Degree: Master
University: University of Baghdad - Laser Institute For Postgraduate Studies
Language: English
University location: Baghdad
First pages:
Abstract: استخدمت مقاييس تداخلات الالياف البلورية الفوتونية في العديد من تطبيقات التحسس. في هذا البحث, تم استخدام الالياف البلورية الفوتونية ذو القلب الصلب المستندة على مقياس تداخل ماخزندر, الذي يسلك حساسية عالية لمعامل الانكسار ومختلف المركبات العضوية المتطايرة، من دون الحاجة الى اي مواد قابلة للاختراق. مقياس التداخل المدمجة ,القوية ويتكون من نهاية ليف بصري بلوري ,الليف البصري البلوري مرتبط مع الليف التقليدية ذات النمط المنفرد ((SMF - 28هذا الارتباط يكون باقل خسارة dB(0.19) في منطقة الارتباط فتحات فراغات الليف تنهار كليا, وتسمح بلتهيج واعادة التركيب للانماط القلب والغلاف .وفي منطقة الارتباط الانماط الاساسية لليف البصري التقليدي تبدا بالحيود عندما تدخل الجزء المنهار من منطقة الارتباط لليف البلوري الفوتوني . بسبب الحيود ، يوسع النمط ويسمح لاثارة نمطين رئيسيين في نهاية اليف البصري الفوتوني.الجهاز يعكس الطيف ويظهر نمط تداخل كدالة جيبية التي تظهر ازاحة بالطيف البصري بشكل مختلف عندما تتسل جزيئات المركبات العظوية المتطايرة الى فتحات الليف البصري البلوري. استخدم ليزر دايود كمصدر ضوئي وبطول موجي 1550 nm ، حيث تم استخدام محلل الطيف الضوئي (OSA) الحساس للغاية في رصد وتسجيل الطيف المنعكس. استخدم ثلاثة انواع من السوائل الكيميائية (N - الهكسين، الميثانول وبروبانول)، كل هذه السوائل الكيميائية وابخرتها لها شفافية عالية في منطقة الطيف المرئي والمنطقة تحت الحمراء القريبة. في هذه التجربة، وجدنا افضل زمن الاستجابة لهذا المتحسس هو من (30 - 35) ثانية لكميات قليلة جدا من هذه السوائل، كما تم دراسة تاثير طول المتحسس على قيمة الازاحة للطول الموجي ، تم اختبار خمسة اطوال مختلفة من PCF ذو القلب الصلب70,50,40,30and 20) nm). حدود الكشف في هذا الجهاز تم من خلالها تسجيل ازاحة في الطول الموجي لنسب من ابخرة مواد كيمياوية تصل لغاية (4.4) nm للبخار الهكسان عندما يكون طول رئس المتحسس (20)mm . في هذا العمل, الحد الاقصى للحساسية التي تم الحصول عليها للمركبات العضوية المتطايرة هي mol \15420 nm في بخار الهكسان .وقد تحققت بعض نتائج المحاكاة باستخدم برنامج COMSOL multiphysics ,تم استخدم هذا البرنامج لتصميم الليف البصري البلوري وايجاد توجيه دايود ليزر 1550 nm داخل الليف البصري البلوري عندما يتغير معامل الانكسار نتيجة لدخول ابخرة المركبات العضوية المتطايرة(هكسان, بروبان, وميثان) وملئها لفتحات الليف. نتائج mulyiphsics COMSOL عندما تسلل ابخرة السوائل الى فراغات الليف البلوري الفوتوني بدلا من الهواء. وعندما يتسلل بخار السائل الى PCF ذو النواة الصلبة (LMA - 10) الذي يؤدي الى تغيير في معامل الانكسار الفعال للPCF، والتي بدورها تؤثر على انتقال ليزر داخل PCF بسبب قيمة معاملات الانكسار للمركبات العضوية المتطايرة. ويظهر نتيجة لذلك ان طاقة طيف انتقال الليزر تخفضت بعد تسلل البخار مع التغير في الطول الموجي المركزي لليزر الدايود. | Photonic crystal fiber interferometers are used in many sensing applications. In this work, an in - reflection photonic crystal fiber (PCF) based on Mach - Zehnder (micro - holes collapsing) (MZ) interferometer, which exhibits high sensitivity to different volatile organic compounds (VOCs), without the needing of any permeable material. The interferometer is robust, compact, and consists of a stub photonic crystal fiber of large - mode area, photonic crystal fiber spliced to standard single mode fiber (SMF) (corning - 28), this splicing occurs with optimized splice loss 0.19 dB. In the splice regions the voids of the holey fiber are completely collapsed, which allows the excitation and recombination of core and cladding modes. The device reflection spectrum exhibits a sinusoidal interference pattern which shifts differently when the voids of the PCF are infiltrated with VOC molecules. Laser diode with wavelength 1550nm has been used as a pump light source, where a highly sensitive optical spectrum analyzer (OSA) was used to monitor and record the reflected spectra. Three types of chemical liquids used (N - Hexane, Methanol and Propanol), all of these chemical liquids and their vapor have a high transparency for visible and NIR spectrum. In this experiment, we found the best response time to this sensor is from (30 - 35) sec for very few quantities from these liquids which approximately measured in microliter, also it was studied the effect of the length of the head sensor on the volume of shift of the wave length, five different lengths of solid core PCF (LMA - 10) (70,50,40,30, and 20) mm were tested.The detection limits of our device associated with the maximum shifts of the wave length is 4.4nm for N - Hexane vapour when the length of the head sensor 20mm.In this work, the maximum sensitivity obtained of volatile organic compounds is 15420nm/mol at the vapor of N - Hexane.Some simulation results have been achieved by using the COMSOL mulyiphsics program. It used to design the photonic crystal fiber large - mode area and find the guiding of laser 1550 nm at this fiber when change the refractive index cladding of the photonic crystal fibers by filling the hole of cladding in vapor of (N - Hexane, propanol, methanol) at 1550 nm, The results of the COMSOL mulyiphsics when infiltration of the air holes for the PCF by vapor liquids instead of air, due the change value of the effective refractive indices of the VOCs, the power of the transmission spectrum of laser decreased after infiltration with change in the center wavelength of the laser diode

التحقق عدديا وعمليا من مبادل حراري ذو سائل نانوي في منظومة التبريد والتهوية والتدفئة مع الكشف بالليزر == Numerical and Experimental Investigation of a Nanofluid Heat Pipe Heat Exchanger in HVAC System with Laser Detection

Author name: ايسر عبد الرزاق الاميري
Supervisor name: حسين علي جواد | زينب فاضل مهدي
General topic: Laser Science
Specific topic: Laser Applications in Mechanical Engineering
Degree: Doctorate
University: University of Baghdad - Laser Institute For Postgraduate Studies
Language: English
University location: Baghdad
First pages:
Abstract: The improvement of energy saving in heat pipe heat exchanger system was investigated .Theoretical work was done to study the effect of coating with nanomaterials on the thermal performance of HPHE to enhance the energy saving. Temperature distribution and thermal resistance for different nano materials (BN, WC, HFB2, MgO and MOSi2), metal and metal oxide (Ag, Cu, AL, BeO, Al2O3 and CuO) on fins were studied. The maximum enhancement of the thermal performance at the evaporator section in steady state operation condition was (5.072, 5.063, 5.075 and 5.069) for (WC, HFB2, MgO and MOSi2) respectively and (5.829) for (BN) at the same section in transient operation condition while at the same section in steady state operation condition (5.063, 5.064, 5.07, 5.068, 5.075 and 5.076) for (Ag, Cu, AL, BeO, Al2O3 and CuO) respectively was detected. The best nano material for enhancement the thermal performance of HPHE are BN for nanomaterial ,Al for nano metal and CuO for nano metal oxide .The thermal performance of seven thicknesses of CuO coating layers on HPHE fins was also studied. Results showed that the enhancement of the thermal performance is decreasing with the increment of coating thickness at the evaporator section of transient conditions (5.076, 5.075, 5.073, 5.072, 5.070, 5.068 and 5.067) for (10, 25, 50, 75, 100,125and150)μm thicknesses respectively. Experimental work was done to examine the general performance of thermosyphon heat pipe at four concentrations (0.05, 0.2, 0.6 and 1) wt. % of nanofluid. Two CW diode lasers (532,650) nm were used as a detection system to determine the variation of the concentration within the system operation. The results showed that fourteen percent reduction in thermal resistance is detected for 0.05wt.% relative to the DI - water . The shorter time of steady state condition of operation, the higher values of total thermal effectiveness, energy saving and energy balance ratio of HPHE were satisfied at 0.05wt.%. The maximum value of relative powers of 0.05wt% nanofluid concentration is detected compared with the other concentrationsdue to the low density of nanofluid concentration. The start sensing and ending detection powers are (0.1, 1) W respectively of this type of nanofluid.

معالجة ارتباط اللجام العالي باستخدام ليزر الدايود 940 نانومتر : دراسة مقارنة في الجسم الحي == High Frenal Attachment Treatment Using 940 nm Diode Laser In Vivo Comparative Study

Author name: اسماء ستار عبود
Supervisor name: علي شكر محمود
General topic: Laser Science
Specific topic: Laser Applications in Medicine - Dentistry
Degree: Master
University: University of Baghdad - Laser Institute For Postgraduate Studies
Language: Arabic
University location: Baghdad
First pages:

التوليد والسيطرة على التشويش في اتصالات التردد الراديوي - البصري == Chaos Generation and Control in RF - Optical Communications System

Author name: اسراء علي ياسين
Supervisor name: قيس عبد الستار النعيمي
General topic: Laser Science
Specific topic: Laser Applications in Physics
Degree: Doctorate
University: University of Baghdad - Laser Institute For Postgraduate Studies
Language: Arabic
University location: Baghdad
First pages:
Abstract: تتناول هذه الاطروحة تنفيذ وتقصي موضوع الاتصالات الضوئية الفوضوية .ونظرا لمتطلبات السرية العالية، تستخدم الاتصالات الضوئية الفوضوية لتشفير الرسائل بين وحدات الارسال والاستقبال.ان الطريقة التي استخدمت للحث على السلوك الفوضوي هي طريقة التغذية المرتدة الضوئي - الالكتروني باستخدام جهاز من محاسن هذا المضمن هو عرض النطاق الترددي ودرجة التعقيد العالية. استند عمل النظام الى طريقة التغذية المرتدة. في هذا النظام، يكون جهاز مذبذب وحدة الارسال مسار مغلق بينما يكون جهاز الاستلام مسار مفتوح يستلم اشارة الفوضى من وحدة الارسال عبر وصلة الالياف الضوئية. تم البحث عمليا في طريقتين لتشفير الرسائل الى اشارة الفوضى. ان هاتين الطريقتين هما التعديل المشوش والتنكر المشوش. لقد بدانا من اختراع نظام الفوضى ودراسة خصائصه وتحديد عناصر السيطرة التي تؤدي الى حالات مختلفة من سلوك النظام. وهكذا تم تقصي الطريق الى الفوضى في مذبذب جهاز الارسال. ولملاحظة سلوك النظام، تم تحديد الرسم المتشعب من خلال تغيير العنصر المتحكم. ان عنصر التحكم هو القدرة البصرية الخارجة من الثنائي الليزري . وجرى بحث التسلسل الزمني وطاقة الطيف واعادة تكوين مساحة الطور. وقد تم بحث موضوع تزامن كلا الطريقتين. وتم الحصول على الرسالة المرسلة في وحدة الارسال من خلال تزامن المذبذب في وحداتي الارسال والاستقبال. وهكذا تم الحصول على الرسالة المستخرجة عند وحدة الاستلام. ان عرض النطاق الترددي لاشارة الفوضى الحاملة هو 200 ميكاهيرتز. وتكون قيمة القدرة الضوئية الخارجة من ثنائي اليزر والذي هو العامل المتحكم في نظامنا هذا في كسب الطوق المرتد في مذبذب الارسال بين (0.8 - 0.9) ملي واط. الرسالة كانت عبارة عن تردد راديوي 100 ميكا هيرتز وقدرة 0 ملي ديسبل. | In this thesis, the chaotic optical communication is implemented and investigated experimentally. Due to the high security requirements, chaotic optical communication is used to encrypt the message between the transmitter and the receiver units. The method which is used to induce chaotic behavior is electro - optical feedback loop by using a Mach - Zehnder modulator. The advantage for this modulator is a high bandwidth and high complexity. The system is a unidirectional feedback loop. In the scheme of unidirectional, the oscillator of the transmitter unit is a closed loop while the oscillator of the receiver unit is an open loop that receives the chaotic signal from the transmitter via an optical fiber link. Two setups were investigated experimentally to encrypt the message to the chaotic carrier signal. These methods are chaos modulation and chaos masking. We have started from creation the chaotic dynamics studied its properties and determined the control parameters that lead to various situations of the behavior of the system. The rout to the chaos for the transmitter oscillator has been investigated. To observe behavior of the system through changing of the control parameter, the bifurcation diagram is plotted. The control parameter is the output optical power of the laser diode. Time series and power spectrum of the time series is extracted by using Fast Fourier Transform FFT. The phase space reconstruction has been examined. The synchronization of two setups has been investigated. The sent message is extracted by the oscillators synchronization in the transmitter unit and the receiver unit. The extracted message has been obtained at the receiver unit. The bandwidth of the chaotic signal is about 200 MHz. The output optical power of the laser diode which is the variable control parameter of our setup in the feedback loop gain of the transmitter oscillator is between (0.8 - 0.9) mW.The message is a radio frequency at 100 MHz with power 0 dBm and is attenuated below this level with the noise level when modulated with the chaotic carrier.

تصنيع مواد متوافقة احيائيا للعظام التعويضية باستخدام الليزر ووسائل تقليدية == Fabrication of Biocompatible Material for Bone Implants Using Laser and Conventional Means

Author name: هدیل فیاض عباس
Supervisor name: رائد عبد الوھاب اسماعیل | ولید خلف حمودي
General topic: Laser Science
Specific topic: Laser Applications in Physics
Degree: Master
University: University of Technology
Language: English
University location: Baghdad
First pages:
Abstract: The present work describes coating the titanium implants with biocompatible materials (ceramics or composites). Three techniques were implemented to materialize this work; these are : pulsed laser deposition, spray pyrolysis, and electrochemical deposition. In these techniques, the influence of deposition temperature, solution concentration, polymer and H2O2 addition, buffer layer sandwiching, and electrolytes combinations were tested. The obtained films’ properties were investigated by using Fourier Transform Infrared Spectroscopy (FTIR), Atomic Force Microscope (AFM), Optical Microscope, X - ray Diffraction (XRD), Scanning Electron Microscope (SEM), Vickers’ hardness instrument, and Simulated Body Fluid (SBF).Composite films prepared by pulsed laser deposition showed the formation of polycrystalline hydroxyapatite of low crystallinity due to the addition of polymeric shrimp crusts. These films had (80 - 90 nm) spherical grains and constitute only (20 - 25%) of the favorable range (80 - 200 nm), and good hardness (≈550 HV). Pure hydroxyapatite (ceramic) films had (11 - 15 nm) surface roughness and an average grain size of (48 - 65 nm) which represents (7 - 31%) of the favorable range. All these films were porous, have good adhesion, and uniform surface morphology. Best results of pulsed laser deposition technique were obtained at 125oC deposition temperature. Films prepared by spray pyrolysis showed porous polycrystalline A and B - type carbonated hydroxyapatite and single crystalline α - Ca3(PO4)2; of relatively low crystallinity and hardness increased with deposition temperature. Post annealing at 400oC and 800oC for film prepared at 350°C of (0.0325 M) solution concentration has raised the hardness from 222 HV to 488 HV and 1204.25 HV respectively. The films of (0.0325 M) solution concentration had (101 - 105 nm) average grain size and were (78 - 100%) of the favorable range, whereas the films of (0.0406 M) solution concentration had (92 - 96 nm) and made (74 - 100%) of the favorable range. Good bioactivity and adhesion strength were obtained from these films which were enhanced significantly after post annealing. Optimum results were obtained from films prepared at 350oC of (0.0325 M) solution concentration after post annealing. Films prepared by electrochemical deposition technique showed uniform and highly porous polycrystalline B - type carbonated hydroxyapatite and polycrystalline α - Ca3(PO4)2. These films had an average grain size of (66 - 93 nm) when prepared from ((NH4)2HPO4 and Ca(NO3)2) whereas the grain size was (87 - 118 nm) when prepared from (Na3PO4 and Ca(NO3)2) with low roughness values. They had (45 - 68%) and (64 - 87%) respectively of the useful grain size in the favorable range (80 - 200 nm). The films covering area increased after H2O2 addition. These films had poor adhesion but this slightly improved together with the roughness after a buffer layer was deposited.The composite films had low crystallinity, grain size, hardness, and poor adhesion. Films prepared at 70oC from both electrolytes combinations ((NH4)2HPO4 with Ca(NO3)2, and Na3PO4 with Ca(NO3)2) had the best surface morphology and crystallinity with an optimum hardness (≈475HV). All these films had very fast dissolution rate in Simulated Body Fluid. Spray pyrolysis deposition technique proved to be the most promising technique for biocompatible materials fabrication for bone implants requirement

فعالية المضاد البكتيري لاكاسيد المعادن النانوية المحضرة بواسطة الاستئصال بالليزر في سائل == Antibacterial Activity of Metals Oxide Nanoparticles Induced by Laser Ablation in Liquid

Author name: فرح عبد الكريم عبد الامير
Supervisor name: خولة صلاح خشان | غسان محمد سلمان
General topic: Laser Science
Specific topic: Laser Applications in Physics
Degree: Master
University: University of Technology
Language: English
University location: Baghdad
First pages:
Abstract: With the increasing of bacterial resistance against antibiotics, nanoparticles studies was appeared together with growing need for substituting theseantimicrobial agents. Recently, it has been demonstrated that metal oxides nanoparticles exhibits bactericidal effect against both bacteria strains.In this research, three kinds of metal oxide nanoparticles (Nickel oxide, Copper oxide and Titanium dioxide) colloidal solutions synthesized using laser ablation of nickel, copper and titanium pellet immersed in de - ionized water. Pulsed Nd : YAG laser with 1٠٦٤ nm wavelength and different laser energies (40, 80, 120, 160 and 200 mJ) was used to irradiate the targets for various ablation times : 5 (75 pulse), 10 (150 pulse), 15 (225 pulse) and 20 min (300 pulse).The UV - Visible absorption spectrum of NiO nanoparticles exhibited broad bands whose intensity decreased continuously above ~210 nm. The UV - Visible absorption spectrum of the CuO nanoparticles solution showed absorption peak around ~275 nm and another peak with low intensity around ~645 nm. While absorption spectrum of TiO2 nanoparticles exhibited strong absorption domination on the spectrum below ~360 nm. In all three metal oxide nanoparticles, absorption intensity increased with the laser energy and ablation time due to increase nanoparticles concentrations in liquid. Fourier Transform Infrared spectroscopy characterization confirmed the formation of metal oxide nanoparticles. All three metal oxides nanoparticles gave absorption bands below ~600 cm−1 arising from inter - atomic vibrations. X - ray Diffraction pattern of nanoparticles proved the presence of (111), (200) planes which belong to NiO and ( - 111), (112) planes that assigned to CuO and (101), (112), ( - 403) planes that related to TiO2. TransmissionElectron Microscopy measurement showed NiO, CuO and TiO2 nanoparticles with nearly spherical shapes and sizes at 2 - 21 nm, 3 - 40 nm and 6 - 30 nm respectively.The antibacterial activity of nanoparticles carried out against four types of bacteria : Escherichia coli, Pseudomonas aeruginosa, and Proteus vulgaris (gramnegative bacteria), Staphylococcus aureus (gram - positive bacteria) firstly by liquid medium method. 1000 μg ml - 1 concentration was the best - used concentration of nanoparticles for inhibiting growth of both bacteria strains. Among the three tested types of nanoparticles (NiO, CuO and TiO2) at highest concentration (1000 μg ml - 1), TiO2 NPs showed the highest antibacterial activity against Escherichia coli and Pseudomonas aeruginosa. NiO NPs showed the highest antibacterial activity against Staphylococcus aureus while CuO NPs showed the highest antibacterial activity against Proteus vulgaris. Results also indicated that metal oxide nanoparticles and amoxicillin would have a synergistic effect on inhibiting of bacterial growth. Amoxicillin showed inhibitory rate about 74.8% against Escherichia coli and 76.28% against Staphylococcus aureus. In the case of NiO, CuO and TiO2 nanoparticles at concentration 1000 μg ml - 1 with Amoxicillin, antibacterial activity of Amoxicillin enhanced to about 81.5%, 90% and 81.9% against Escherichia coli and to about 86.9%, 91% and 90.7% against Staphylococcus aureus. Therefore, CuO nanoparticles and amoxicillin have the best synergic effect on inhibiting both bacteria strains. The antibacterial activity of the three metal oxides nanoparticle combined with Amoxicillin was also tested by well diffusion method against Escherichia coli and Staphylococcus aureus. In this method, CuO NPs at concentration 1000 μg ml - 1 along with Amoxicillin showed the highest inhibition zone against Escherichia coli (26.0±1.00 mm), while showed complete inhibition of bacteria against Staphylococcus aureus.

Adaptation Of Copper Vapor Laser System For Electrical Applications

Author name: احسان عدنان جبار
General topic: Laser Science
Specific topic: Laser Applications in Electrical Engineering
Degree: Master
University: University of Baghdad - Laser Institute For Postgraduate Studies
Language: English
University location: Baghdad
First pages:

علاج ليزر الثنائي الصمام لخلايا السرطان خارج وداخل الجسم الحي == A Diode Laser Therapy For Cancer Cells In Vitro And In Vivo

Author name: رجاء صيهود عباس صالح
Supervisor name: Ali Sh. Mahmood | Eman H. Al-Taee
General topic: Laser Science
Specific topic: Laser Applications in Medicine - Veterinary Medicine
Degree: Master
University: University of Baghdad - Laser Institute For Postgraduate Studies
Language: English
University location: Baghdad
First pages:

تاثير ليزر النيديميوم ـ ياك مفتاح عامل النوعية على بعض المعلومات الفسلجية في خميرة الـ Saccharomyces cerevisiae == Effect Of Q-Switched Nd: YAG Laser On Some Physiological Parameters Of Saccharomyces Cerevisiae

Author name: نور عبد الجبار جداح
Supervisor name: Ghazi M. Aziz
General topic: Laser Science
Specific topic: Laser Applications in the Life Sciences
Degree: Master
University: University of Baghdad - Laser Institute For Postgraduate Studies
Language: English
University location: Baghdad
First pages:

تاثير ليزرالنمط المستمر 532 نانوميتر على حيوية Pseudomonas aeruginosa و Staphylococcus aureus بوجود المتحسس الضوئي خارج الجسم الحي == Effect Of 532Nnm CW Laser On Viability Of Photosensitized Pseudomonas Areuginosa And Staphylococcus Aureus In Vitro

Author name: سمية خليل ابراهيم الزبيدي
Supervisor name: امل مصطفى مكي
General topic: Laser Science
Specific topic: Laser Applications in the Life Sciences
Degree: Doctorate
University: University of Baghdad - Laser Institute For Postgraduate Studies
Language: English
University location: Baghdad
First pages:

تاثير التشعيع بالليزر الواطيء القدرة على الخط الخلوي لابيضاض الدم == Effect Of Low Power Laser Irradiation On Leukaemic Cell Line

Author name: ليلى محمد حسن العامري
Supervisor name: امل مصطفى مكي | علي حسين ادحية
General topic: Laser Science
Specific topic: Laser Applications in the Life Sciences
Degree: Doctorate
University: University of Baghdad - Laser Institute For Postgraduate Studies
Language: English
University location: Baghdad
First pages:

كتابة محزز الحيود نوع براك على ليف بصري بشكل حرف D باستخدام ليزر الاكسايمر نوع كربتون فلورايد == Writing Of A Bragg Grating On A D-Shaped Optical Fiber Using The KrF Excimer Laser

Author name: شيماء رياض محمد علي ال طحان
Supervisor name: خليل ابراهيم حاجم
General topic: Laser Science
Specific topic: Laser Applications in Electronics and Communications Engineering
Degree: Doctorate
University: University of Baghdad - Laser Institute For Postgraduate Studies
Language: English
University location: Baghdad
First pages:

دراسة عملية تثقيب شرائح الزجاج باستخدام ليزر CO2 == Investigation Of Glass Sheets Hole Drilling Using CO2 Laser

Author name: لينا زكي يحيى محمد
Supervisor name: حسين علي جواد
General topic: Laser Science
Specific topic: Laser Applications in Physics
Degree: Master
University: University of Baghdad - Laser Institute For Postgraduate Studies
Language: English
University location: Baghdad
First pages:

منظومة استشعار حرارة معتمدة على محززات براغ الليفي مكتوبة بواسطة ليزر ايون الارغون 244 نانومتر == Temperature Sensing System Based On Fiber Bragg Gratings Written By 244 nm Ar+ Laser

Author name: رياض خلف احمد
Supervisor name: خليل ابراهيم حاجم
General topic: Laser Science
Specific topic: Laser Applications in Electronics and Communications Engineering
Degree: Doctorate
University: University of Baghdad - Laser Institute For Postgraduate Studies
Language: English
University location: Baghdad
First pages:

تاثير ليزر ثنائي اوكسيد الكاربون 10,6 مايكرومتر على الذوبان الحمضي للمينا بالمقارنة مع فلورايد الفوسفات : دراسة مختبرية == The Effect Of 10.6µm Co2 Laser On Enamel Acid Solubility In Comparison To Acidulated Phosphate Fluoride (An In Vitro Study)

Author name: علي عباس شهيد
Supervisor name: حسين علي جواد
General topic: Laser Science
Specific topic: Laser Applications in Medicine - Dentistry
Degree: Master
University: University of Baghdad - Laser Institute For Postgraduate Studies
Language: English
University location: Baghdad
First pages:

تكوين تركيب فضة دقيقة داخل الزجاج المسامي بليزر الفمتوثانية == Fabrication Of Micro Silver Structures Inside Porous Glass By Fs Laser

Author name: عبد الستار خضير عباس الغانمي
Supervisor name: مازن مانوئيل الياس
General topic: Laser Science
Specific topic: Laser Applications in Physics
Degree: Doctorate
University: University of Baghdad - Laser Institute For Postgraduate Studies
Language: English
University location: Baghdad
First pages:

دراسة التغيرات الحاصلة في درجة الحرارة والنفوذية و التضاريس السطحية لجذر العاج المعالج بالليزر المبتكر مزدوج الطول الموجي 2780و 940 نانومتر == Temperature, Permeability And Surface Morphology Changes Of Radicular Dentine Induced By Novel Dual Wavelength (2780nm, 940nm) Laser

Author name: تمارة سردار محمد سعيد
Supervisor name: حسين علي جواد
General topic: Laser Science
Specific topic: Laser Applications in Medicine - Dentistry
Degree: Doctorate
University: University of Baghdad - Laser Institute For Postgraduate Studies
Language: English
University location: Baghdad
First pages:

تشخيص دقائق البلاديوم النانوية المحضرة بطريقة بوليول == Characterization Of Prepared Palladium Nanoparticles By Polyol Method

Author name: اسراء كريم عبد الله
Supervisor name: زينب فاضل مهدي
General topic: Laser Science
Specific topic: Laser Applications in Physics
Degree: Master
University: University of Baghdad - Laser Institute For Postgraduate Studies
Language: English
University location: Baghdad
First pages:

دراسة مقارنة لليزر الايربيوم ـ ياك باستخدام نوعين من الانظمة الرابطة لقوة الربط القصي لحشوة راتنج الكومبوزت المربوطة بعاج السن == Comparative Study Of Er-YAG Laser With Two Adhesive Systems For Shear Bond Strength Of Composite Resin Bonded Dentin

Author name: عباس علي احمد العامري
Supervisor name: Ali Sh. Mahmood | Mohammed R.Hamid
General topic: Laser Science
Specific topic: Laser Applications in Medicine - Dentistry
Degree: Master
University: University of Baghdad - Laser Institute For Postgraduate Studies
Language: English
University location: Baghdad
First pages:

دراسة طيفية لاحدى الجسيمات النانوية المحضرة بطرق مختلفة == A Spectroscopy Study on Nanoparticles Prepared by Different Methods

Author name: ايلاف اياد كاظم
Supervisor name: وجيهة عبد الدائم | لازم حسن عبود
General topic: Laser Science
Specific topic: Laser Applications in Physics
Degree: Master
University: University of Babylon - College Of Science For Girls - Department Of Laser Physics
Language: English
University location: Babylon
First pages:

دراسة تاثير طاقة الليزر وطول موجته على تغيير خواص المحاليل النانوية الغروية لـ Pt وسبيكة Au:Ag المحضرة بطريقة القشط الليزري == Study the Effect of Laser Energy and its Wavelengths on Variation of Nano colloidal Properties of Pt and Au : Ag Synthesized by Laser Ablation

Author name: نغم محمد عبيد
Supervisor name: Glib A.Al-Dahash
General topic: Laser Science
Specific topic: Laser Applications in Physics
Degree: Master
University: University of Babylon - College Of Science For Girls - Department Of Laser Physics
Language: Arabic
University location: Babylon
First pages:

دراسة تاثير اشعة الليزر متعدد الاطوال الموجية على بعض خصائص الدم == Study effect the multi-wavelength laser radiation on some characteristics of blood

Author name: هدى كاظم محسن
Supervisor name: صادق حسن لفتة | سامي عبد الحسين حبانة
General topic: Laser Science
Specific topic: Laser Applications in Physics
Degree: Master
University: University of Babylon - College Of Science For Girls - Department Of Laser Physics
Language: Arabic
University location: Babylon
First pages:

لحام البوليمر من خلال الامرار باستعمال نموذج ماكنة ليزر الدايود ذات التحكم الرقمي المبرمج == Through Transmission Polymer Welding Using Prototype Diode Laser CNC Machine

Author name: زياد اياد طه
Supervisor name: خليل ابراهيم حاجم
General topic: Laser Science
Specific topic: Laser Applications in Welding Engineering
Degree: Doctorate
University: University of Baghdad - Laser Institute For Postgraduate Studies
Language: English
University location: Baghdad
First pages:

تاثير ليزر ثنائي اوكسيد الكاربون مع او بدون معجون الهايدروكسي اباتايت النانوي في غلث النبيبات العاجية == The Effects Of CO2 Laser With Or Without Nano - Hydroxyapatite Paste In The Occlusion Of Dentinal Tubules

Author name: محمد عبود المالكي
Supervisor name: علي شكر محمود
General topic: Laser Science
Specific topic: Laser Applications in Medicine - Dentistry
Degree: Master
University: University of Baghdad - Laser Institute For Postgraduate Studies
Language: English
University location: Baghdad
First pages:

تصميم وتنفيذ دائرة تشغيل اخماد نشط لكشف فوتون مفرد == Design And Implementation Ac Active Quenching Driving Circuit For Signle Photon Detection

Author name: عمار خلف عبد الحسين
Supervisor name: خليل ابراهيم حاجم
General topic: Laser Science
Specific topic: Laser Applications in Electronics and Communications Engineering
Degree: Master
University: University of Baghdad - Laser Institute For Postgraduate Studies
Language: English
University location: Baghdad
First pages:

Simulated Dissipation And Thermal Effects On Experimentally Generated Coherent And Squeezed States

Author name: اسماعيل شنان
Supervisor name: Raad Sami Fyath
General topic: Laser Science
Specific topic: Laser Applications in Electronics and Communications Engineering
Degree: Doctorate
University: University of Baghdad - Laser Institute For Postgraduate Studies
Language: English
University location: Baghdad
First pages:

تصنيع وتشخيص تراكيب الكاربون النانوية باستخدام تقانة التذرية بالليزر النبضي في الطور السائل == Fabrication And Characterization Of Carbon Nanostructures Using Liquid Phase Pulsed Laser Ablation

Author name: احمد رياض عباس الحموي
Supervisor name: حسين علي جواد
General topic: Laser Science
Specific topic: Laser Applications in Mechanical Engineering
Degree: Doctorate
University: University of Baghdad - Laser Institute For Postgraduate Studies
Language: English
University location: Baghdad
First pages:

استجابة العاج و اللب السني لفعالية تحضير الحفرة السنية من النوع الاول بواسطة ليزر الايربيوم- ياك بالمقارنة مع الطريقة التقليدية : دراسة سريرية على اسنان بشرية == Dentin And Pulp Response To The Use Of Er : YAG Laser Ablation Versus Dental Drill For Class I Cavity Preparation : An In Vivo Study On Human Teeth

Author name: مها وليد الغزالي
Supervisor name: حسين علي جواد
General topic: Laser Science
Specific topic: Laser Applications in Medicine - Dentistry
Degree: Master
University: University of Baghdad - Laser Institute For Postgraduate Studies
Language: English
University location: Baghdad
First pages:

توليد شعاع تيراهرتز بواسطة التفاعل اللاخطي لحزمة ليزرية شديدة مع بلازما ممغنطة == Terahertz Radiation Generation By Nonlinear Interaction Of Intense Laser Beam With Magnetoplasma

Author name: منذر باقر حسن الخاقاني
Supervisor name: عبد الهادي مطشر الجنابي
General topic: Laser Science
Specific topic: Laser Applications in Physics
Degree: Doctorate
University: University of Baghdad - Laser Institute For Postgraduate Studies
Language: English
University location: Baghdad
First pages:

دراسة المواد المتراكبة المدعمة المعالجة بالليزر == An Investigation Of Laser Treated Reinforced Composites

Author name: مصدق عبد الخالق
Supervisor name: زينب فاضل مهدي
General topic: Laser Science
Specific topic: Laser Applications in Mechanical Engineering
Degree: Master
University: University of Baghdad - Laser Institute For Postgraduate Studies
Language: English
University location: Baghdad
First pages:

توليد النبضات القصيرة الموهنة لتماثل مصدر الفوتون المنفرد لمنظومة التجفير الكمي == Generation Of Attenuated Short Pulses To Mimic A Single Photon Source For Quantum Cryptography System

Author name: فؤاد علي ياسين
Supervisor name: Shalane Khasro Tawfeeq
General topic: Laser Science
Specific topic: Laser Applications in Electronics and Communications Engineering
Degree: Master
University: University of Baghdad - Laser Institute For Postgraduate Studies
Language: English
University location: Baghdad
First pages:

Quantum Bit Error Rate Performance Test For A Quantum Cryptography System

Author name: احمد اسماعيل خليل
Supervisor name: Shelan Khasro Tawfeeq
General topic: Laser Science
Specific topic: Laser Applications in Electronics and Communications Engineering
Degree: Master
University: University of Baghdad - Laser Institute For Postgraduate Studies
Language: English
University location: Baghdad
First pages:

دراسة تاثير الطولين الموجيين 808 نانومتر و 532 نانومتر لليزر الدايود على العناصر البصرية لبوليمر PMMA == Study The Effect Of (532 And 808) nm Wavelengths Of Laser Diode On Optical Elements Of PMMA Polymer

Author name: محمود شاكر موسى الحسناوي
Supervisor name: محمد كريم طاهر العاني
General topic: Laser Science
Specific topic: Laser Applications in Physics
Degree: Master
University: University of Baghdad - Laser Institute For Postgraduate Studies
Language: English
University location: Baghdad
First pages:
1 2 3 4 5 ... 7