اخلاص جابر محمود الليباوي

Contamination of terrestrial systems by microplastics (MPs) has become a critical environmental hazard, but detection of such contaminants in a complex soil system is a challenge for conventional analytical techniques. This research aims to assess the potential of Laser-Induced Breakdown Spectroscopy (LIBS) for the detection and differentiation of different types of microplastics, including HDPE, LDPE, PP, PS, and PVC, dispersed in the soil of Al Najaf, Iraq. Soil samples were collected from different functional zones, namely, Industrial, Commercial, Agricultural, Residential, and Roadside, at the surface level and 30 cm depth. Detection was done by measuring the intensity of the C/H ratio, where the Carbon emission line was fixed at 247.86 nm, and the Hydrogen emission line was fixed at 388.47 nm, and the results were compared with the atomic spectra given in the NIST database. The results showed a strong relationship between different types of polymers and different functional zones, where the industrial zone was showed spectral signatures most consistent with HDPE, the roadside was showed a predominance of PS spectral fingerprints, and the agricultural zone showed consistency in PVC vertical distribution. Although the residential prediction was in favor of LDPE, the empirical results pointed towards PET and PVC, which was due to the effect of synthetic fibers and debris. The conclusion of the research was that the proposed method of LIBS, which uses the ratio method, may help reduce the influence of the background matrix interferences of carbonate-rich and gypsiferous soils, thereby providing a cost-effective and rapid solution for the environmental analysis of the diffusion of microplastics in arid terrestrial environments.

Methods employed in the analysis of uranium in soil samples that have high complexity are quite expensive and necessitate dangerous chemical treatment. The current research provides an inexpensivemethod of analysis through the use of LIBS for detecting uranium spectral signatures in 20 surface and 30 cm depth soil samples collected in Al-Najaf governorate, Iraq. The LIBS analysis of the samples was conducted by employing a nanosecond Nd: YAG laser (wavelength 1064 nm) in addition to the NIST atomic data base. The recorded emission spectra covered 161.559 to 898.826 nm, revealing matrix homogeneity in the UV and NIR regions. Relative intensities varied significantly from 0.00257 to 0.923 at 30 cm depth, indicating variations in the observed uranium spectral response among the analyzed samples. The number of identified uranium-associated spectral lines ranged from 5 to 8 per sample. The neutral uranium (U I) line at 358.262 nm appeared consistently across all samples, indicating its potential as a spectral marker for rapid uranium screening. Conversely, a prominent enhancement of the singly ionized (U II) line at 373.339 nm was uniquely observed in surface sample S5 due to localized matrix effects. It is concluded that this work establishes a foundational preliminary spectral library that supports rapid qualitative screening and environmental radiological monitoring in Al-Najaf province.

This research attempts to minimise the heat affected zone (HAZ) width that forms in the laser cutting process of Ti-6Al-4V sheets. The experimental results of the HAZ for 32 sets of five CO2 laser cutting parameters (with the assist pressure of argon gas) were used to build the artificial neural network (ANN) model, each with a different material thickness, cutting speed, laser beam power, assist gas pressure and lens focal length percentage. A relationship formula was derived by connecting the laser cutting parameters based on the connection weights obtained from the developed ANN model. The MAPE value for the comparison between the predicted and experimental HAZ width was 4.192%. The Monte Carlo optimisation method was performed using 2,000 simulations to identify a suitable optimal solution. The results showed that the most effective transfer function type in the hidden layers was the linear function. The model was highly sensitive for the cutting speed (CS), assist gas pressure (GP) and beam power (BP) parameters and less sensitive for the parameters of thickness (T) and lens focal length (LFL). The optimum values of the laser cutting parameters that produced a minimum value of HAZ was T = 1 mm, LFL = 30%, BP = 3 kW, CS = 1 m/min and GP = 14 bars.

This research presents an attempt to study the influence of laser cutting parameters such as thickness, Lens Focal Length, Beam Power, Cutting Speed and Gas Pressure on the Heat Affected Zone (HAZ) width. Two predictive models were developed using Artificial Neural Network (ANN) and multi regression modeling method. The relative importance of laser cutting parameters on (HAZ) width was determined based on (ANN) neuron weights and (ANOVA) method. The comparison between the experimental data and the predicted data indicats that the (ANN) model has attain an accuracy for predicting (HAZ) more than the multi regression model with a coefficient of determination of (R2)=85.02%.

In this study, MATLAB program was used to simulate Nd:YAG laser beam welding process for stainless steel sheet material AISI 304. A comparison between developed model and experimental results as well as statistical criteria was calculated for this comparison in order to evaluate the accuracy level of developed model results. The results showed that the determination coefficient (R2) for bead width and penetration depth was equal to 98.9% and 98.91% respectively as well as mean error ME values are very close to zero.

This research is devoted to study the effect of a laser beam power TEA-CO2 , Nd- YAG laser, and thermal properties of the materials when it is constant once and varying another once with the time on the penetration and cutting speeds. It is concluded that the processes of penetration and cutting by using laser Nd-YAG is the best comparative with using of laser TEA-CO2, penetration speeds when (P = P0, C = C0, and ρ = ρ0) by using laser Nd-YAG greater than penetration speeds by using of laser TEA-CO2 by 15.5 approximately while penetration speeds when (P = P(t), C = C0, and ρ = ρ0) by using laser Nd-YAG greater than penetration speeds by using of laser TEA-CO2 by 8.519 approximately. In addition, the temperature of the evaporation of material plays an important role in the processes of penetration and cutting and whenever temperature of the evaporation of material less the cutting and penetration speeds are greater. (MATLAB 8) program was implemented for all simulation processes are related.

نجح هذا البحث في الكشف عن البصمات الطيفية للميكروبلاستيك وتصنيفها الأولي في عينات التربة باستخدام تقنية مطيافية الانبعاث الذري المثار بالليزر (LIBS). تقدم الدراسة حلاً تحليلياً واعداً ومباشراً لرصد التلوث الدقيق بالبلاستيك دون الحاجة لاستخلاص كيميائي معقد أو معالجة مطولة للعينات. تساهم النتائج في بناء قاعدة بيانات طيفية تساعد على تحديد أنواع المواد البلاستيكية الدقيقة وتقييم مدى انتشارها البيئي في التربة. يمثل هذا الإنجاز خطوة مهمة نحو توسيع استخدامات تقنيات الليزر الحديثة في حماية التربة وتطوير أساليب الرقابة البيئية المستدامة.

نجح هذا البحث في تحقيق الكشف السريع والمباشر عن عنصر اليورانيوم في عينات من تربة محافظة النجف الأشرف باستخدام تقنية مطيافية الانبعاث الذري المثار بالليزر (LIBS). تتميز هذه الدراسة بإجراء التحليل الميداني دون الحاجة لمعالجات كيميائية معقدة، مما يختصر الوقت والجهد مقارنة بالطرائق التقليدية للتحليل البيئي. تزود النتائج المستحصلة الجهات المختصة ببيانات دقيقة لتقييم السلامة الإشعاعية ومراقبة جودة التربة في المنطقة بشكل مستمر. يمثل نشر هذا البحث إضافة علمية تمهد الطريق لتوسيع استخدامات تقنيات الليزر الحديثة في مجالات المسح البيئي والوقاية من التلوث.

The Scientific Journal of King Faisal University