Al-Azhar University, Faculty of Science (Boys)Al-Azhar Bulletin of Science1110-253532Issue 2-B20211201Optical Characterization of Stabilized Atmospheric Pressure Pin to Plate Plasma Source1919860110.21608/absb.2021.91532.1132ENAhmedAbdelradiMeteorologist,Meteorological Authority (EMA),Cairo,EgyptAhmedSamirCenter of Plasma Technology, Al-Azhar University in Cairo, Cairo, EgyptFaroukElaksharDepartment of Physics, Faculty of Science, Al-Azhar University in Cairo, Cairo, EgyptAbdouGaramoonDepartment of Physics, Faculty of Science, Al-Azhar University in Cairo, Cairo, EgyptMansourElSabaghCenter of Plasma Technology, Al-Azhar University in Cairo, Cairo, EgyptJournal Article20210824DC Stabilized Discharges (DCSD) was generated in atmospheric pressure argon for a pin to plate. In this paper, discharge with a flowing argon gas into the air (plasma Source) is investigated by optical emission spectroscopy technique. The emission spectra of excited species of atomic-hydrogen, N<sub>2</sub> and Ar were observed and measured. The rotational and vibrational temperatures of the discharge were measured by comparing modelled optical emission spectra with masured spectra from the discharge by using several different vibrational bands of the 2nd positive system (SPS) of N<sub>2</sub> ( N<sub>2</sub>[C <sup>3</sup>Π<sub>u</sub>] → N<sub>2</sub>[B <sup>3</sup>Π<sub>g</sub>]). The optical characteristics of the discharge shown that the DCSD was found to be non-equilibrium with rotational temperature (T<sub>r</sub>) of 1087 K and vibrational temperature (T<sub>v</sub>) of 1661 K. Boltzmann plot method has been applied to estimate the electronic excitation temperature which was found to be 1.36 eV and 1.1 eV for discharges with argon flow rates of 1.0 SLM & 0.5 SLM respectively. This finding proved the strong non-equilibrium nature of the discharge conditions of the current work.https://absb.journals.ekb.eg/article_198601_bbbfc3463b58702e6dc5388055ba75fc.pdfAl-Azhar University, Faculty of Science (Boys)Al-Azhar Bulletin of Science1110-253532Issue 2-B20211201Coronavirus epidemic model with isolation and nonlinear incidence rate112220567410.21608/absb.2021.84983.1126ENAfaf S.ZaghroutDepartment of Mathematics, Faculty of Science (Girls), Al-Azhar University, Cairo, EgyptYoussraAliDepartment of Mathematics, Faculty of Science (Girls), Al-Azhar University, Cairo, EgyptDoaa K.ElpagouriDepartment of Mathematics, Faculty of Science (Girls), Al-Azhar University, Cairo, EgyptJournal Article20210730In our article we proposed an epidemiological model consisting of five compartments that describe corona virus disease with isolation. We developed an SEIR system to produce the dynamical behaviour of infection by adding isolation compartment F(t) (that is because of the isolation of the infected individuals will reduce the spread of the disease). We formulated our model with nonlinear incidence rate. First, we discussed the positivity and boundedness of the model. Then we calculated the basic reproduction number of the model under certain conditions. By analysing the local and the global stability of our model, it is noticed that this stability depends on the basic reproductive number. We found that the system has no endemic equilibrium state if R<sub>0</sub> < 1. Finally, we discussed the global stability by using Lyapunov function of Goh-volterra type with LaSalle’s invariance principle. It was shown that the system has a unique equilibrium point which is global asymptotically stable.https://absb.journals.ekb.eg/article_205674_ada2a645efb3f661a1b622a8c709e129.pdfAl-Azhar University, Faculty of Science (Boys)Al-Azhar Bulletin of Science1110-253532Issue 2-B20211201Monte carlo method estimates for internal dosimetry of well differentiated thyroid cancer patients233120421610.21608/absb.2021.93331.1133ENMaged M. E.El-dinRadiation Protection Department, Egyptian Nuclear and Radiological Regulatory Authority, Cairo, Egypt.Amr M.KanyFaculty of science Al-Azhar University, Cairo, Egypt.EmanMassoudJeddah International College, Jeddah, Saudi Arabia.Ahmed Y.El-AgamawiFaculty of medicine Al-Azhar University, Cairo, Egypt.Mohamed R.Ezz El-dinRadiation Protection Department, Egyptian Nuclear and Radiological Regulatory Authority, Cairo, Egypt.Journal Article20210905During radiotheranostic procedures, radioiodine-131(<sup>131</sup>I)activities deliver high internal gamma (ɣ) doses to the patient’s organs. Thus, studying the internaldoses of patients is highly required to predict the stochastic or deterministiceffect of gamma radiation that may occur to patients.The objective ofthis study is to calculatethe internal doses for 11 critical organs or body tissues insideWell Differentiated Thyroid Cancer (WDTC) patients’ bodiesafter receiving diagnostic and therapeutic <sup>131</sup>I activitiesorally during 6days post administration.Internal effective doses delivered tocritical organs are estimated mathematically using Monte Carlo simulation model in which the actual geometry, volume, mass of organs and the source localization wasdesigned based onthe patients’ CT images and Oak Ridge National Laboratory (ORNL) phantom.Thus, an average sized human phantom was constructed using MCNP5in whichtwo <sup>131</sup>I sources were distributed in the abdominal and the thyroid gland sections.No significant radiation effect is expected during diagnostic procedures for the investigated organs including the thyroid itself. However,some deterministic effects or induction of thyroid cancer might be observedfor patients undergoing postoperative radiotherapy with largeprescribed activities. https://absb.journals.ekb.eg/article_204216_dacbc8431887f3285aa917b191f9cf23.pdfAl-Azhar University, Faculty of Science (Boys)Al-Azhar Bulletin of Science1110-253532Issue 2-B20211201Pulse Propagation Through a medium Consists of Two Three-Level Atoms334320567010.21608/absb.2021.100248.1145ENRasha N.RabeaMathematics Department, Faculty of Science (Girls Branch), Al-Azher University, Nasr City 11884, Cairo, Egypt.Mervat A.EldeberkyMathematics Department, Faculty of Science (Girls Branch), Al-Azher University, Nasr City 11884, Cairo, Egypt.Mohamed M. A.AhmedMathematics Department, Faculty of Science (Boys Branch) , Al-Azher University, Nasr City 11884, Cairo, Egypt.Journal Article20211017The coherent propagation of two optical short pulses through a resonant medium consisting of two three-level atoms in the configuration is investigated. A self-consisting analytical solution without steady state or adiabatic approximations is presented. The electric field in the model studied consists of two co-propagating plane waves, each of which is in near resonance with a transition in the absorber. The density matrix of two three level atoms is studied. Also, the reduced density matrices are stated. The present approach for the semiclassical treatment of resonant coherent interactions in three-level atoms represents a generalization of the Maxwell- Bloch equations for a two-level system. The Maxwell-Bloch equations reduced to the non-linear pendulum equation. The solution shows that the two pulses can propagate simultaneously without loss under some conditions about the pulses and the medium. The propagation of the two pulses through the medium without any constrains approves the self -induced transparency (SIT) phenomenon.https://absb.journals.ekb.eg/article_205670_3526995525f03e8f62aca6a31c911925.pdfAl-Azhar University, Faculty of Science (Boys)Al-Azhar Bulletin of Science1110-253532Issue 2-B20211201VORR: A New Round Robin Scheduling Algorithm455420901210.21608/absb.2021.99340.1141ENAfaf A.AbdelhafizDepartment of Mathematics, Division of Computer Science, Faculty of Science, Al-Azhar University (Girls Branch), Cairo, Egypt.Journal Article20211003Task scheduling on resources is critical for improving the performance of real-time systems. Enormous efforts have recently and rapidlybeen proposed by many researchers with improvements in various accessible algorithms of the task scheduling process. Each improvement contributes to the optimization of the system act. The field of enhancing CPU scheduling algorithms (such as the Round Robin algorithm RR) is still open. The Round Robin scheduling has many negatives, such as high waiting time, high turnaround time, or a high number of context switches. Such negatives affect the performance of the algorithm badly. This paper discusses a new approach named, VORR (Variant On Round Robin), which is one of the improvements and enhancements to the Round Robin scheduling algorithm. It effectively exploits the CPU by setting up an effective time quantum based on the median of burst times. The experimental results have demonstrated the worth of the proposed approach in comparison with the traditional Round Robin scheduling algorithm and its recent editions in terms of average waiting time, average turnaround time, and number of context switches. Also, it enhances the response time for some RR algorithms.https://absb.journals.ekb.eg/article_209012_ff432c5cdf32e75ff16deea1b0d32135.pdf