Data Security Model for Cloud Computing

From the perspective of data security, which has always been an important aspect of quality of service, cloud computing focuses a new challenging security threats. Therefore, a data security model must solve the most challenges of cloud computing security. The proposed data security model provides a single default gateway as a platform. It used to secure sensitive user data across multiple public and private cloud applications, including Salesforce, Chatter, Gmail, and Amazon Web Services, without influencing functionality or performance. Default gateway platform encrypts sensitive data automatically in a real time before sending to the cloud storage without breaking cloud application. It did not effect on user functionality and visibility. If an unauthorized person gets data from cloud storage, he only sees encrypted data. If authorized person accesses successfully in his cloud, the data is decrypted in real time for your use. The default gateway platform must contain strong and fast encryption algorithm, file integrity, malware detection, firewall, tokenization and more. This paper interested about authentication, stronger and faster encryption algorithm, and file integrity.     

First-Principle Study of Electronic and Half-Metallic Ferromagnetic Properties of Vanadium (V)-Doped Cubic BP and InP

In this study, we use the first-principle calculations of density functional theory with gradient generalized approximation of Wu–Cohen to investigate the doping effect of vanadium impurity on structural, electronic and magnetic properties of In_1?x V _x P and B_1?x V _x P alloys at various concentrations x = 0.0625, 0.125 and 0.25. Owing to the metallic nature of majority spin and semiconducting minority spin, the In_1?x V _x P compounds exhibit a half-metallic character with total magnetic moments of 2 μ _B, while the B_1?x V _x P has metallic nature for all concentrations. The results of exchange parameters revealed that exchange coupling between vanadium atoms and the conduction band is ferromagnetic, confirming the magnetic feature of In_1?x V _x P and B_1?x V _x P. From our findings, we have predicted that the In_1?x V _x P alloys seem to be potential materials for spintronics.     

A Hybrid Virtual Cloud Learning Model during the COVID-19 Pandemic

The COVID-19 pandemic has affected the educational systems worldwide, leading to the near-total closures of schools, universities, and colleges. Universities need to adapt to changes to face this crisis without negatively affecting students’ performance. Accordingly, the purpose of this study is to identify and help solve to critical challenges and factors that influence the e-learning system for Computer Maintenance courses during the COVID-19 pandemic. The paper examines the effect of a hybrid modeling approach that uses Cloud Computing Services (CCS) and Virtual Reality (VR) in a Virtual Cloud Learning Environment (VCLE) system. The VCLE system provides students with various utilities and educational services such as presentation slides/text, data sharing, assignments, quizzes/tests, and chatrooms. In addition, learning through VR enables the students to simulate physical presence, and they respond well to VR environments that are closer to reality as they feel that they are an integral part of the environment. Also, the research presents a rubric assessment that the students can use to reflect on the skills they used during the course. The research findings offer useful suggestions for enabling students to become acquainted with the proposed system’s usage, especially during the COVID-19 pandemic, and for improving student achievement more than the traditional methods of learning.     

Reliability Prediction of Composite Tubular Structure Under Mechanical Loading by Finite Element Method

The diversified use of filamentary composites in harsh marine environments, recorded in recent years, has prompted researchers to focus their work on the reliability prediction. Through failure criteria, Tsai–Wu and the maximum stress, the reliability of multilayer tubular structures under mechanical loading is the subject of this paper, where Monte Carlo method estimated the failure probability. A sensitivity analysis was performed in order to identify the influence of the different parameters, such as materials’ properties, geometry, manufacturing and loading, on the reliability of the composite cylindrical structure studied. To achieve a high accuracy of the results, we have carried out 105 simulations. The results showed great influence on pressure loading, ply thickness and finally winding angle of filament composite.     

Digestive enzymes characterization of krill (Euphausia superba) residues deoiled by supercritical carbon dioxide and organic solvents

In this study, Enzyme activities of krill were characterized before and after lipid extraction by supercritical carbon dioxide (SC-CO₂) and organic solvent, n-hexane and acetone. Krill SC-CO₂ extraction was performed under the conditions of temperature range from 35 to 45 °C and pressure, 150–250 bar for 2.5 h with a constant flow rate of 22 g/min. Extraction yields of lipids increased with pressure and temperature. The digestive enzyme activities of protease, lipase and amylase of SC-CO₂ treated krill residues were slightly decreased comparing to organic solvent, n-hexane and acetone treated residues. In SC-CO₂ treated samples, all of the digestive enzymes showed slightly higher temperature stability. In the other hand the crude extracts of SC-CO₂ and n-hexane treated krill samples showed almost same optimum pH and pH stability for each of the digestive enzymes. It was also found in SDS-PAGE that there are no significant differences in protein patterns of the crude extracts of untreated, SC-CO₂, n-hexane and acetone treated krill indicating no denaturation of proteins.     

Linear model-based estimation of blood pressure and cardiac output for Normal and Paranoid cases

Provisioning a generic simple linear mathematical model for Paranoid and Healthy cases leading to auxiliary investigation of the neuroleptic drugs effect imposed on cardiac output (CO) and blood pressure (BP). Multi-input single output system identification in consistency with the Z-Transform is considered an essential role in the exploration of linear discrete system identification. Twenty Paranoid and 20 Healthy peer cases have been chosen to lie under study. The generated CO model forming two poles and two zeros produced a root–mean-squared error (RMSE) of 0.109 and an average RMSE of 1.39 due to Paranoid cases. On the other hand, Healthy cases obtained model held three poles and two zeros with RMSE equal to 0.17 and an average of 0.63. The BP model with four poles and two zeros showed a 2.15 and 21.69 for RMSE and an average RMSE, respectively, for Paranoid cases, whereas seven poles and two zeros provided an RMSE of 5.7 and an average RMSE of 17.19 for Healthy cases. The obtained results were provided a generic models of CO with promising outcomes for Paranoid and Healthy cases. Moreover, the BP model has less and yet acceptable results in both Paranoid and Healthy cases.     

A comparative study of tunable Ba1−x Sr x TiO3 thin film capacitors prepared by rf-sputtering and liquid-phase deposition

Abstract

Ba_1?x Sr _x TiO₃ thin film capacitors have been successfully prepared using rf-sputtering and a metal organic deposition (MOD) method. The structure, microstructure and composition of the BSTO films are presented. Films grown on lanthanum aluminate LAO(100) showed c-axis preferred growth orientation. Broad paraelectric-to-ferroelectric transitions were observed in films prepared by both methods. The tunability of the capacitance by means of an appplied electric field is examined using various capacitor geometries. A decrease in the capacitance exceeding 75% at 77 K was obtained from the MOD deposited films under an electric field strength of 0.3 MV/cm. On the other hand, the tunability of the capacitance in the rf-sputtered films ranged from 5 to 10% at 77 K and at 20 kV/cm, while it exceeds 50% in some films. The results are compared with the predictions of Devonshire's phenomenological theory.     

Synthesis of MIL-101@g-C<Subscript>3</Subscript>N<Subscript>4</Subscript> nanocomposite for enhanced adsorption capacity towards CO<Subscript>2</Subscript>

MIL-101@g-C₃N₄ nanocomposite was prepared by solvothermal synthesis and used for CO₂ adsorption. The parent materials (MIL-101 and g-C₃N₄) and the MIL-101@g-C₃N₄ were characterized by X-ray diffraction, argon adsorption/desorption, Fourier transform infrared spectroscopy, thermal analysis (TG/DTA), transmission electronic microscopy, and Energy-dispersive X-ray spectroscopy. The results confirmed the formation of well-defined MIL-101@g-C₃N₄ with interesting surface area and pore volume. Furthermore, both MIL-101 and MIL-101@g-C₃N₄ were accomplished in carbon dioxide capture at different temperatures (280, 288, 273 and 298 K) at lower pressure. The adsorption isotherms show that the nanocomposite has a good CO₂ adsorption affinity compared to MIL-101. The best adsorption capacity is about 1.6 mmol g^?1 obtained for the nanocomposite material which is two times higher than that of MIL-101, indicating strong interactions between CO₂ and MIL-101@g-C₃N₄. This difference in efficacy is mainly due to the presence of the amine groups dispersed in the nanocomposite. Finally, we have developed a simple route for the preparation of an effective and new adsorbent for the removal of CO₂, which can be used as an excellent candidate for gas storage, catalysis, and adsorption.     

Dielectric features of two grades of bi‐oriented isotactic polypropylene

The dielectric properties of two grades of bi‐oriented isotactic polypropylene were studied with a variety of techniques: breakdown field measurements, dielectric spectroscopy, thermally stimulated depolarization currents (Is), and direct‐current (dc) conduction I values. Standard polypropylene (STPP) and high‐crystallinity polypropylene (HCPP) films were investigated. Measurements were carried out over a wide temperature range (?150°C/+125°C). The breakdown fields in both materials showed a very small difference. On the other hand, the dielectric losses and dc conduction I values were significantly lower in HCPP. Both materials showed a decrease in the dielectric loss versus temperature in the range 20–90°C; this is favorable for application in alternating‐current power capacitors. The analysis of the dc I value allowed us to find evidence of two main conduction mechanisms: (1) below 80°C in both materials, a hopping mechanism due to the motion of electrons occurred in the amorphous phase, and (2) above 80°C, ionic conduction occurred in HCPP, and hopping conduction occurred in STPP. © 2015 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2015 , 132, 42224.