Free vibration analysis of FG plates under thermal environment via a simple 4-unknown HSDT

Amina Attia,Amina Tahar Berrabah,Abdelmoumen Anis Bousahla,Fouad Bourada,Abdelouahed Tounsi,S. R. Mahmoud 국제구조공학회 2021 Steel and Composite Structures, An International J Vol.41 No.6

A 4-unknown shear deformation theory is applied to investigate the vibration of functionally graded plates under thermal environment. The plate is fabricated from a functionally graded material mixed of ceramic and metal with continuously varying material properties through the plate thickness. Three types of thermal loadings, uniform, linear and nonlinear temperature rises along the plate thickness are taken into account. The present theory contains four unknown functions as against five or more in other higher order shear deformation theories. The through-the-thickness distributions of transverse shear stresses of the plate are considered to vary parabolically and vanish at upper and lower surfaces. The present model does not require any problem dependent shear correction factor. Analytical solutions for the free vibration analysis are derived based on Fourier series that satisfy the boundary conditions (Navier's method). Benchmark solutions are firstly considered to evaluate the accuracy of the proposed model. Comparisons with the solutions available in literature revealed the good capabilities of the present model for the simulations of vibration responses of FG plates. Some parametric studies are carried out for the frequency analysis by varying the volume fraction profile and the temperature distribution across the plate thickness.

Entrepreneurship by a Green Pharmacy

Amina ATHER 이화여자대학교 아시아여성학센터 2013 이화여자대학교 아시아여성학센터 학술대회자료집 Vol.2013 No.1

Early reduced bone formation following burn injury in rats is not inversely related to marrow adiposity

Amina El Ayadi,Ron C. Helderman,Celeste C. Finnerty,David N. Herndon,Clifford J. Rosen,Gordon L. Klein 대한골다공증학회 2019 Osteoporosis and Sarcopenia Vol.5 No.3

Objectives: The objective of the study was to determine whether postburn reduction of bone formation occurred earlier than 2e3 weeks after burn injury and whether that reduction was inversely related to marrow adiposity. Methods: Using a rat model of burn injury with sacrifice at 3 days postburn, we measured serum osteocalcin, a biomarker of bone formation, as well as a regulator of glucose metabolism, and counted tibial marrow adipocytes. Results: Serum osteocalcin was reduced as early as 3 days postburn, coinciding with a trend toward decline in marrow adipocyte number rather than demonstrating an inverse relationship with adipocyte count. Conclusions: Factors that may be responsible for the dissociation include lack of circulating sclerostin, previously reported, increased energy demands following burn injury, increased sympathetic tone and perhaps oxidative stress. The relationship between bone formation and marrow adiposity is complex and subject to a variety of influences.

Performance Analysis of Blockchain Consensus Protocols-A Review

Amina Yaqoob,Alma Shamas,Jawad Ibrahim International Journal of Computer ScienceNetwork S 2023 International journal of computer science and netw Vol.23 No.6

Blockchain system brought innovation in the area of accounting, credit monitoring and trade secrets. Consensus algorithm that considered the central component of blockchain, significantly influences performance and security of blockchain system. In this paper we presented four consensus protocols specifically as Proof of Work (PoW), Proof of Stake (PoS), Delegated Proof of Stake (DPoS) and Practical Byzantine Fault-Tolerance (PBFT), we also reviewed different security threats that affect the performance of Consensus Protocols and precisely enlist their counter measures. Further we evaluated the performance of these Consensus Protocols in tabular form based on different parameters. At the end we discussed a comprehensive comparison of Consensus protocols in terms of Throughput, Latency and Scalability. We presume that our results can be beneficial to blockchain system and token economists, practitioners and researchers.

Galvanic Coupling Effect on Pitting Corrosion of 316L Austenitic Stainless Steel Welded Joints

Amina Sriba,Jean‑Bernard Vogt 대한금속·재료학회 2021 METALS AND MATERIALS International Vol.27 No.12

The aim of this work is to display the effect of the chemical composition of the filler metal (ER316LN and ER308LN) on thecorrosion resistance of 316L austenitic stainless steel welded joints, performed using GTAW process. The redistribution ofchemical elements from the base metal and from the filler metal in the fusion zone during the welding operation produces avariation in the microscopic structure along the welded joint. The latter comprises distinct microstructural zones identifiedas fusion zone, fusion line (partially melted zone), heat affected zone, and the unaffected base metal with their own electrochemicalresponse. Our results revealed that the base metal constitutes the anodic region in the welded joint, while the fusionzones behave as the cathodic part protected against corrosion. From the electrochemical corrosion tests, it is concluded thatthe welded joint 316L/ER308LN exhibits a better resistance to pitting corrosion than the welded joint 316L/ER316LN, butis less resistant to corrosion by dissolution.

Facile single mode electrospinning way for fabrication of natural product based silver decorated polyurethane nanofibrous membranes: Prospective medicated bandages

Amina, M.,Amna, T.,Hassan, M.S.,Ibrahim, T.A.,Khil, M.S. Elsevier 2013 Colloids and surfaces. A, Physicochemical and engi Vol.425 No.-

In this study we have introduced for the first time a new class of bionanocomposite scaffold composed of virgin olive oil/poly(urethane) blend system decorated with silver nanoparticles via single mode electrospinning approach. Olive oil is a natural material that contains vitamin E, antioxidants and phenol that affect cytokine production by skin cells when applied topically and help in recovery process when skin damage occurs. Herein, we standardized optimal concentration (5%) of olive oil to get spinable solution for fabrication of oil blended nanofiberous membranes. The fabricated bionanocomposite membranes were characterized through scanning electron microscopy, energy dispersive X-ray analysis and X-ray diffraction pattern to study effect of olive oil on morphological and molecular behavior. The antimicrobial effects, viability and proliferation of as-spun bionanocomposite was studied using Escherichia coli (Gram negative) and NIH 3T3 fibroblasts as model strain and cell line respectively. The SEM-EDX and XRD results confirmed well oriented nanofibers and good dispersion of oil. The outcome of results also indicated that incorporation of olive oil in polymer media affected both the morphology and size of PU nanofiber membranes. The bionanocomposite was able to inhibit the growth of E. coli and revealed non-cytotoxic behavior towards the fibroblast cell culture. Thus the olive oil blended scaffold embedded with silver nanoparticles could be used as a prospective antimicrobial agent which can potentially reduce wound contamination and simultaneously help in wound healing process. Finally, our results clearly indicate the potential of designing bionanocomposite as medicated bandages for skin diseases, burns and damaged skin treatment.

A refined four variable plate theory for thermoelastic analysis of FGM plates resting on variable elastic foundations

Amina Attia,Abdelmoumen Anis Bousahla,Abdelouahed Tounsi,S. R. Mahmoud,Afaf S. Alwabli 국제구조공학회 2018 Structural Engineering and Mechanics, An Int'l Jou Vol.65 No.4

In this paper, an efficient higher-order shear deformation theory is presented to analyze thermomechanical bending of temperature-dependent functionally graded (FG) plates resting on an elastic foundation. Further simplifying supposition are made to the conventional HSDT so that the number of unknowns is reduced, significantly facilitating engineering analysis. These theory account for hyperbolic distributions of the transverse shear strains and satisfy the zero traction boundary conditions on the surfaces of the plate without using shear correction factors. Power law material properties and linear steady-state thermal loads are assumed to be graded along the thickness. Nonlinear thermal conditions are imposed at the upper and lower surface for simply supported FG plates. Equations of motion are derived from the principle of virtual displacements. Analytical solutions for the thermomechanical bending analysis are obtained based on Fourier series that satisfy the boundary conditions (Navier’s method). Non-dimensional results are compared for temperature-dependent FG plates and validated with those of other shear deformation theories. Numerical investigation is conducted to show the effect of material composition, plate geometry, and temperature field on the thermomechanical bending characteristics. It can be concluded that the present theory is not only accurate but also simple in predicting the thermomechanical bending responses of temperature-dependent FG plates.

Water Quality Assessment and Turbidity Prediction Using Multivariate Statistical Techniques: A Case Study of the Cheurfa Dam in Northwestern Algeria

( Amina Addouche ),( Ali Righi ),( Mehdi Mohamed Hamri ),( Zohra Bengharez ),( Zahia Zizi ) 한국공업화학회 2022 공업화학 Vol.33 No.6

This work aimed to develop a new equation for turbidity (Turb) simulation and prediction using statistical methods based on principal component analysis (PCA) and multiple linear regression (MLR). For this purpose, water samples were collected monthly over a five year period from Cheurfa dam, an important reservoir in Northwestern Algeria, and analyzed for 12 parameters, including temperature (T°), pH, electrical conductivity (EC), turbidity (Turb), dissolved oxygen (DO), ammonium (NH₄ ⁺), nitrate (NO₃ ^-), nitrite (NO₂ ^-), phosphate (PO₄ ^3-), total suspended solids (TSS), biochemical oxygen demand (BOD5) and chemical oxygen demand (COD). The results revealed a strong mineralization of the water and low dissolved oxygen (DO) content during the summer period. High levels of TSS and Turb were recorded during rainy periods. In addition, water was charged with phosphate (PO₄ ^3-) in the whole period of study. The PCA results revealed ten factors, three of which were significant (eigenvalues >1) and explained 75.5% of the total variance. The F1 and F2 factors explained 36.5% and 26.7% of the total variance, respectively and indicated anthropogenic pollution of domestic agricultural and industrial origin. The MLR turbidity simulation model exhibited a high coefficient of determination (R² = 92.20%), indicating that 92.20% of the data variability can be explained by the model. TSS, DO, EC, NO₃ ^-, NO₂ ^-, and COD were the most significant contributing parameters (p values << 0.05) in turbidity prediction. The present study can help with decision-making on the management and monitoring of the water quality of the dam, which is the primary source of drinking water in this region.

The Evaluation of Ceiling Depth Impact on Lighting and Overall Energy Consumption of Building with Skylights

Amina Irakoze(아미나 이라코제),Kee Han Kim(김기한),Lee Young-A(이영아) 대한건축학회 2019 대한건축학회 학술발표대회 논문집 Vol.39 No.2

This study aimed at the assessment of ceiling depth impact on skylight energy performance through OpenStudio integrated Radiance and EnergyPlus program. A ceiling as deep as 1.5 to 3m was analyzed for skylight to roof ratio from 1% to 25%. Through a parametric analysis, the study concluded that 8%, 9%, 10% and 11% skylight to roof ratio were optimal in terms of total building energy consumption for a ceiling depth of 1.5m, 2m, 2.5m and 3m respectively. In addition, the results showed that the usually recommended 5% skylight to roof ratio was only efficient when no ceiling depth was included in the simulation model. Therefore, study induced that ceiling depth was crucial in the analysis of skylight and should not be excluded for the simplicity of simulation model.

From Localization to Globalization : Multi-language Services into 70 languages for Company L

Amina Matyakubova 한국EA학회 2018 한국EA학회 학술발표논문집 Vol.2018 No.12