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Investigation of Thermal Stress Distribution in Laser Spot Welding Process
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The objective of this paper was to study the laser spot welding process of low carbon steel sheet. The investigations were based on analytical and finite element analyses. The analytical analysis was focused on a consistent set of equations representing interaction of the laser beam with materials. The numerical analysis based on 3-D finite element analysis of heat flow during laser spot welding taken into account the temperature dependence of the physical properties and latent heat of transformations using ANSYS code V.10.0 to simulate the laser welding process. The effect of laser operating parameters on the results of the temperature profile were studied in addition to the effect on thermal stresses  and dimensions of the laser welded workpiece which showed good correlations between analytical and numerical results. It was found that the temperature gradients during laser welding are usually very large and it was viewed that very high temperature at the center of the workpiece, and is decreased very significantly as propagating along the radial direction. Also it found that the thermal residual stresses around the laser spot due to plastic strains were very small and localized within 1.0 mm range. It is concluded that the laser welding process is effective to reduce the welding residual stress. The stresses along the lateral direction of the workpiece changed from compression at the spot under the laser beam and tension away from the spot at the end of welding to tension at the spot under the laser beam and compression away from the spot when it cooled, which are in a good agreement with the published results.

   

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Publication Date
Fri Feb 08 2019
Journal Name
Iraqi Journal Of Laser
Random Number Generation for Quantum Key Distribution Systems Based on Shot-Noise Fluctuations in a P-I-N Photodiode
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A simple setup of random number generator is proposed. The random number generation is based on the shot-noise fluctuations in a p-i-n photodiode. These fluctuations that are defined as shot noise are based on a stationary random process whose statistical properties reflect Poisson statistics associated with photon streams. It has its origin in the quantum nature of light and it is related to vacuum fluctuations. Two photodiodes were used and their shot noise fluctuations were subtracted. The difference was applied to a comparator to obtain the random sequence.

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Publication Date
Mon Mar 08 2021
Journal Name
Baghdad Science Journal
Theoretical study to find the thermal stress and strain generated in the Wood silica using lasers
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In this research study theory to find the stress and emotion gases in the glass as a result of exposure to pulses of the laser beam has been the study using vehicles three major on-system axes cylindrical (r, 0, z), where I took three models of glass silica glass soda glass fused and shedtwo types of lasers where the study showed that the thermal stresses and emotions ...

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Publication Date
Sat Feb 20 2010
Journal Name
Indian Journal Of Science And Technology
Investigation on picosecond laser ablation of dental material using FIB/SEM techniques
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Publication Date
Thu Oct 14 2021
Journal Name
Iraqi Journal Of Physics
Investigation of nonlinear optical properties for laser dyes-doped polymer thin film
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Solutions of dyes Rhodamine 6G (Rh6G) and Coumarin480(C480) were prepared at five concentrations (1x10-3, 5x10-4, 1x10-4, 5x10-5 and1x10-5) mol/l, the mixing was stirred to obtain on a homogenous solution, the(poly methyl-methacrylate) (PMMA) was solved by chloroform solvent with certain ratio, afterward (PMMA+Rh6G) and (PMMA+C480) thin films were prepared by casting method on glass block which has substrate with dimensions (7.5 x2.5)cm2, the prepared samples were left in dark place at room temperature for 24 hours to obtain uniform and homogenous thin films. UV-VIS absorption spectra, transmission spectra and fluorescence spectra were done to measure linear refractive index and linear absorption coefficient. The nonlinear optical proper

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Publication Date
Tue Nov 01 2016
Journal Name
Journal Of Economics And Administrative Sciences
Proposal of Using Principle of Maximizing Entropy of Generalized Gamma Distribution to Estimate the Survival probabilities of the
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Abstract

In this research we been estimated the survival function for data suffer from the disturbances and confusion of  Iraq Household Socio-Economic Survey: IHSES II 2012 , to data from a five-year age groups follow the distribution of the Generalized Gamma: GG. It had been used two methods for the purposes of estimating and fitting which is the way the Principle of Maximizing Entropy: POME, and method of booting to nonparametric smoothing function for Kernel, to overcome the mathematical problems plaguing integrals contained in this distribution in particular of the integration of the incomplete gamma function, along with the use of traditional way in which is the Maximum Likelihood: ML. Where the comparison on t

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Publication Date
Wed Feb 01 2023
Journal Name
Baghdad Science Journal
Spectrophotometric Method Combined with HPLC for Bisphenol F Determination in Plastic Bottled Water and Thermal Paper
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Based on the diazotization-coupling reaction, a new, simple, and sensitive spectrophotometric method for determining of a trace amount of (BPF) is presented in this paper. Diazotized metoclopramide reagent react with bisphenol F produces an orange azo-compound with a maximum absorbance at 461 nm in alkaline solution. The experimental parameters were optimized such as type of alkaline medium, concentration of NaOH, diazotized metoclopramide amount, order additions, reaction time, temperature, and effect of organic solvents to achieve the optimal performance for the proposed method. The absorbance increased linearly with increasing bisphenol F concentration in the range of 0.5-10 μg mL-1 under ideal conditions, with a correlati

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Publication Date
Tue Jul 01 2025
Journal Name
The International Journal Of Advanced Manufacturing Technology
Impact of tool geometry on void evolution, stress non-uniformity, and thermomechanical interaction in friction stir welding of T-joints using CEL simulation and experimental validation
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Although Friction Stir Welding (FSW) is broadly invested in joining aluminum alloys, welding T-joint configurations display revealing challenges due to the interface’s intricate material flow and stress development. Defect formation, including voids and lack of fusion, as well as sudden response forces and residual stresses, can substantially undermine joint performance. This study presents an innovative three-dimensional finite element model to predict the coupled thermomechanical conditions experienced during the friction stir welding (FSW) of AA 6061-T6 lap T-joint design. The study identifies the geometrical parameters of the FSW tool, including shoulder and pin diameters, as well as pin form (cylindrical and tapered), as critical var

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Publication Date
Sat Oct 01 2011
Journal Name
Journal Of Engineering
THERMAL BUCKLING OF RECTANGULAR PLATES WITH DIFFERENT TEMPERATURE DISTRIBUTION USING STRAIN ENERGY METHOD
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By using governing differential equation and the Rayleigh-Ritz method of minimizing the total potential energy of a thermoelastic structural system of isotropic thermoelastic thin plates, thermal buckling equations were established for rectangular plate with different fixing edge conditions and with different aspect ratio. The strain energy stored in a plate element due to bending, mid-plane thermal force and thermal bending was obtained. Three types of thermal distribution have been considered these are: uniform temperature, linear distribution and non-linear thermal distribution across thickness. It is observed that the buckling strength enhanced considerably by additional clamping of edges. Also, the thermal buckling temperatures and

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Publication Date
Tue Jan 17 2012
Journal Name
Journal Of Electron Devices
INVESTIGATION OF OPTICAL PROPERTIES OF THE PbS/CdS THIN FILMS BY THERMAL EVAPORATION
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In this work, we have investigated optical properties of the thermally evaporation PbS/CdS thin films. The optical constant such as (refractive index n, dielectric constant εi,r and Extinction coefficient κ) of the deposition films were obtained from the analysis of the experimental recorded transmittance spectral data. The optical band gap of PbS/CdS films is calculate from (αhυ)1/2 vs. photon energy curve.

Publication Date
Tue Feb 12 2019
Journal Name
Iraqi Journal Of Laser
Generation of True Random TTL Signals for Quantum Key-Distribution Systems Based on True Random Binary Sequences
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A true random TTL pulse generator was implemented and investigated for quantum key distribution systems. The random TTL signals are generated by low cost components available in the local markets. The TTL signals are obtained by using true random binary sequences based on registering photon arrival time difference registered in coincidence windows between two single – photon detectors. The true random TTL pulse generator performance was tested by using time to digital converters which gives accurate readings for photon arrival time. The proposed true random pulse TTL generator can be used in any quantum -key distribution system for random operation of the transmitters for these systems

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