Fluctuation properties of laser light after interaction with an atomic system: comparison between two-level and multilevel atomic transitions

The complex internal atomic structure involved in radiative transitions has an effect on the spectrum of fluctuations (noise) of the transmitted light. A degenerate transition has different properties in this respect than a pure two-level transition. We investigate these variations by studying a certain transition between two degenerate atomic levels for different choices of the polarization state of the driving laser. For circular polarization, corresponding to the textbook two-level atom case, the optical spectrum shows the characteristic Mollow triplet for strong laser drive, while the corresponding noise spectrum exhibits squeezing in some frequency ranges. For a linearly polarized drive, corresponding to the case of a multilevel system, additional features appear in both optical and noise spectra. These differences are more pronounced in the regime of a weakly driven transition: whereas the two-level case essentially exhibits elastic scattering, the multilevel case has extra noise terms related to spontaneous Raman transitions. We also discuss the possibility to experimentally observe these predicted differences for the commonly encountered case where the laser drive has excess noise in its phase quadrature.Comment: New version. Accepted for publication in Physical Review

Methods of Protection Against the Attraction and Recruitment of Terrorist Groups Through Social Media

This study aimed to identify the methods that can be used to protect Saudi women from being attracted and recruited by terrorist groups through social media from teaching staff members in Saudi universities. The study used an analytical descriptive methodology to collect data using questionnaires from 382 teaching staff members in Saudi universities. Findings revealed that entertainment, filling leisure time and the desire to know the news were the most dominant motivations among Saudi women for using social media websites. Moreover, the ability to access Saudi women and offer the ideas to them by various and attractive methods, and differentiating by interactive property were the methods used by terrorist groups for attracting and recruiting Saudi women. The study therefore, recommend to develop a comprehensive national strategy aimed at limiting the ability of terrorist groups and organizations to employ digital media in general and social media, especially in attracting and recruiting Saudi nationals

Eddy current modelling using multi-layer perceptron neural networks for detecting surface cracks

A new method for computing fracture mechanics parameters using computational Eddy Current Modelling by Multi-layer Perceptron Neural Networks for detecting surface cracks. The method is based upon an inverse problem using an Artificial Neural Network (ANN) that simulates mapping between Eddy current signals and crack profiles. Simultaneous use of ANN by MLP can be very helpful for the localization and the shape classification of defects. On the other side, it can be described as the task of reconstructing the cracks and damage in the plate profile of  an  inspected  specimen  in  order  to  estimate  its  material properties. This is accomplished by inverting eddy current probe impedance measurements that are recorded as a function of probe position, excitation frequency or both. In eddy current nondestructive evaluation, this is widely recognized as a complex theoretical problem whose solution is likely to have a significant impact on the detection of cracks in material

Photovoltaic Solar Cells and Panels Waste in Jordan: Figures, Facts, and Concerns

Even though the Kingdom of Jordan is moving in the right direction and adopting clean energy sources such as PV plants, the waste problem will eventually emerge within a few decades and will be an overwhelming issue if not addressed early on. According to reports, the installed PV capacity worldwide was around 410 GW in 2017 and is projected to increase to 5000 GW by 2050. Global solar PV waste is anticipated to reach between 5% and 15% of total generation capacity by 2030, with a 25-year average panel lifespan. This study aims to provide an estimation of the amount of PV waste expected within the next decade, and finally expand on the economic and environmental effects. Moreover, this paper's target is to explore the possible effects of PV waste materials in the northern part of Jordan, and the obtained results can be applied to other regions in Jordan. Information about renewable energy in Jordan, retrieved from databases of electricity companies, is utilized to reach an accurate estimation of the amounts of materials that will occur at the end of life. The solar PV panel end of life (EOL) management is a developing field that necessitates additional research and development The obtained findings, figures, and facts about the photovoltaic solar energy sector presented in this study highlight the urgency to develop a suitable system for the collection and management of photovoltaic modules at their end of life.Scopu

Structure and microstructure evolution of Al-Mg-Si alloy processed by equal-channel angular pressing

An ultrafine grained Al–Mg–Si alloy was prepared by severe plastic deformation using the equal-channel angular pressing (ECAP) method. Samples were ECAPed through a die with an inner angle of F = 90° and outer arc of curvature of ¿ = 37° from 1 to 12 ECAP passes at room temperature following route Bc. To analyze the evolution of the microstructure at increasing ECAP passes, X-ray diffraction and electron backscatter diffraction analyses were carried out. The results revealed two distinct processing regimes, namely (i) from 1 to 5 passes, the microstructure evolved from elongated grains and sub-grains to a rather equiaxed array of ultrafine grains and (ii) from 5 to 12 passes where no change in the morphology and average grain size was noticed. In the overall behavior, the boundary misorientation angle and the fraction of high-angle boundaries increase rapidly up to 5 passes and at a lower rate from 5 to 12 passes. The crystallite size decreased down to about 45 nm with the increase in deformation. The influence of deformation on precipitate evolution in the Al–Mg–Si alloy was also studied by differential scanning calorimetry. A significant decrease in the peak temperature associated to the 50% of recrystallization was observed at increasing ECAP passes.Peer ReviewedPreprin

Evaluation of Trivalent and Hexavalent Chromium Retention on Ain Oussera Soil by the Batch Method and Radiotracer Technique.

Major toxicology studies have concluded that Cr (VI) is a highly toxic carcinogen to living organisms, and cause deaths if ingested in large doses. The trivalent form plays an important role in glucose and lipid metabolism for human and animal diets. Industrial activities present in the study area investigated in this paper, such as tanning, production of paints, and cement, are the main sources of chromium in the soil and air, causing chromium pollution. The aim of this study is to investigate the behavior of Cr (III) and Cr (VI) in soil samples from the Ain Oussera area, using the batch method and radiotracer technique. This assessment of chromium adsorption in the soil allows us to examine its impact. The pH effects of initial concentration, adsorbent dose and temperature were investigated. Particle size, X-ray diffraction and neutron activation analysis methods were used to characterize the soil samples. Results of the Freundlich, and Langmuir isotherm models were compared to the obtained experimental data. The thermodynamic parameters ∆H°, ∆S° and ∆G° for the adsorption were determined by using four temperatures, 10, 30, 40 and 60°C. The adsorption process was spontaneous and favoured at a low temperature. The maximum adsorption percentage reached for Cr (III) and Cr (VI) in soil was 90 and 24, respectively, with a spontaneous reaction (∆H°< 0). These results show that hexavalent chromium seeps through soil layers, and reaches the groundwater easily

Evaluation of Trivalent and Hexavalent Chromium Retention on Ain Oussera Soil by the Batch Method and Radiotracer Technique.

Major toxicology studies have concluded that Cr (VI) is a highly toxic carcinogen to living organisms, and cause deaths if ingested in large doses. The trivalent form plays an important role in glucose and lipid metabolism for human and animal diets. Industrial activities present in the study area investigated in this paper, such as tanning, production of paints, and cement, are the main sources of chromium in the soil and air, causing chromium pollution. The aim of this study is to investigate the behavior of Cr (III) and Cr (VI) in soil samples from the Ain Oussera area, using the batch method and radiotracer technique. This assessment of chromium adsorption in the soil allows us to examine its impact. The pH effects of initial concentration, adsorbent dose and temperature were investigated. Particle size, X-ray diffraction and neutron activation analysis methods were used to characterize the soil samples. Results of the Freundlich, and Langmuir isotherm models were compared to the obtained experimental data. The thermodynamic parameters ∆H°, ∆S° and ∆G° for the adsorption were determined by using four temperatures, 10, 30, 40 and 60°C. The adsorption process was spontaneous and favoured at a low temperature. The maximum adsorption percentage reached for Cr (III) and Cr (VI) in soil was 90 and 24, respectively, with a spontaneous reaction (∆H°< 0). These results show that hexavalent chromium seeps through soil layers, and reaches the groundwater easily

THERMOPHORESIS PARTICLE DEPOSITION ON FLAT SURFACES DUE TO FLUID FLOW IN DARCY-FORCHHEIMER POROUS MEDIUM

An analysis is performed for non-Darcy free convection flow over a vertical plate embedded in a thermally stratified, fluid saturated porous medium and taking into account the presence of thermophoresis particle deposition. A finite-difference scheme was used to solve the system of transformed governing equations. Numerical results for the details of the velocity, temperature and concentration profiles which are shown on graphs have been presented. It is shown that the inertia forces have a significant influence on the flow characteristics in this problem. Comparison with previous published work is performed and the results are found to be in excellent agreement