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Numerical and experimental comparison of the vaned diffuser interaction inside the impeller velocity field of a centrifugal pump

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Science China(Technological Sciences) 2011年第2期54卷 286-294页

作者： ATIF Abdelmadjid BENMANSOUR saad BOIS Gerard DUPONT Patrick Laboratory of Advanced Mechanics FGMGP/USTHBBP32 El Alia16111AlgerAlgeria Laboratory of Mechanics of Lille ENSAM-Lille8 Bd Louis XIV59046LilleFrance Laboratory of Mechanics of Lille EC-LilleBP48 Villeneuve d’Ascq59651LilleFrance

The paper refers to the analysis of interactions between the impeller and the vaned diffuser based on the air model of a radial flow *** study deals with a numerical simulation of the flow for a full 360°entire impeller and *** task is carried out closely under the design operating conditions and for one particular position of the impeller blade with respect to the diffuser *** all the results,the focus is mainly on the flow pattern at the exit part inside the impeller facing the diffuser *** results are compared to the available PIV measurements.

关键词： centrifugal pump impeller vaned diffuser rotor-stator interaction

Optoelectronic properties of SnO2 thin films sprayed at different deposition times

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Chinese Physics B 2016年第4期25卷 296-302页

作者： Allag Abdelkrim saad Rahmane Ouahab Abdelouahab Attouche Hafida Kouidri Nabila Laboratoire de Physique des Couches Minces et Applications Universit de Biskra BP 145 RP 07000 Biskra Alg&ie

This article presents the elaboration of tin oxide （SnO2） thin films on glass substrates by using a home-made spray pyrolysis system. Effects of film thickness on the structural, optical, and electrical film properties are investigated. The films are characterized by several techniques such as x-ray diffraction （XRD）, atomic force microscopy （AFM）, ultraviolet- visible （UV-Vis） transmission, and four-probe point measurements, and the results suggest that the prepared films are uniform and well adherent to the substrates. X-ray diffraction （XRD） patterns show that SnO2 film is of polycrystal with cassiterite tetragonal crystal structure and a preferential orientation along the （110） plane. The calculated grain sizes are in a range from 32.93 nm to 56.88 nm. Optical transmittance spectra of the films show that their high transparency average transmittances are greater than 65% in the visible region. The optical gaps of SnO2 thin films are found to be in a range of 3.64 eV-3.94 eV. Figures of merit for SnO2 thin films reveal that their maximum value is about 1.15 x 10-4 Ω-1 at λ = 550 nm. Moreover, the measured electrical resistivity at room temperature is on the order of 10^-2 Ω.cm.

关键词： thin film SnO2 spray pyrolysis thickness properties

Classification COVID-19 Based on Enhancement X-Ray Images and Low Complexity Model

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Computers, Materials & Continua 2022年第7期72卷 561-576页

作者： Aymen saad Israa SKamil Ahmed Alsayat Ahmed Elaraby Department of Information Technology Technical College of ManagementKufaAl Furat Alawsat UniversityIraq Department of Medical Laboratory Techniques Al-Mustaqbal University CollegeHillaIraq Department of Computer Science College of Computer and Information SciencesJouf UniversitySaudi Arabia Department of Computer Science Faculty of Computers and InformationSouth Valley UniversityQenaEgypt

COVID-19 has been considered one of the recent epidemics that occurred at the last of 2019 and the beginning of 2020 that world *** spread of COVID-19 requires a fast technique for diagnosis to make the appropriate decision for the treatment.X-ray images are one of the most classifiable images that are used widely in diagnosing patients’data depending on radiographs due to their structures and tissues that could be *** Neural Networks(CNN)is the most accurate classification technique used to diagnose COVID-19 because of the ability to use a different number of convolutional layers and its high classification *** using CNNs techniques requires a large number of images to learn and obtain satisfactory *** this paper,we used SqueezNet with a modified output layer to classify X-ray images into three groups:COVID-19,normal,and *** this study,we propose a deep learning method with enhance the features of X-ray images collected from Kaggle,Figshare to distinguish between COVID-19,Normal,and Pneumonia *** this regard,several techniques were used on the selected image samples which are Unsharp filter,Histogram equal,and Complement image to produce another view of the *** Squeeze Net CNN model has been tested in two scenarios using the 13,437 X-ray images that include 4479 for each type(COVID-19,Normal and Pneumonia).In the first scenario,the model has been tested without any enhancement on the *** achieved an accuracy of 91%.But,in the second scenario,the model was tested using the same previous images after being improved by several techniques and the performance was high at approximately 95%.The conclusion of this study is the used model gives higher accuracy results for enhanced images compared with the accuracy results for the original images.A comparison of the outcomes demonstrated the effectiveness of ourDLmethod for classifying COVID-19 based on enhanced X-ray images.

关键词： COVID-19 X-ray image enhancement classification CNN SqueezNet model

An efficient hash-based authenticated key agreement scheme for multi-server architecture resilient to key compromise impersonation

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Digital Communications and Networks 2021年第1期7卷 140-150页

作者： Inam ul haq Jian Wang Youwen Zhu saad Maqbool College of Computer Science and Technology Nanjing University o f Aeronautics and AstronauticsNanjing210016China National University of Science and Technology Islamabad4600Pakistan

During the past decade,rapid advances in wireless communication technologies have made it possible for users to access desired services using hand-held *** providers have hosted multiple servers to ensure seamless online services to *** ensure the security of this online communication,researchers have proposed several multi-server authentication schemes incorporating various cryptographic *** to the low power and computational capacities of mobile devices,the hash-based multi-server authenticated key agreement schemes with offline Registration Server(RS)are the most efficient ***,Kumar-Om presented such a scheme and proved its security against all renowned ***,we find that their scheme bears an incorrect login phase,and is unsafe to the trace attack,the Session-Specific Temporary Information Attack(SSTIA),and the Key Compromise Impersonation Attack(KCIA).In fact,all of the existing multi-server authentication schemes(hash-based with offline RS)do not withstand *** deal with this situation,we propose an improved hash-based multi-server authentication scheme(with offline RS).We analyze the security of the proposed scheme under the random oracle model and use the t4Automated Validation of Internet Security Protocols and Applications''(AVISPA)*** comparative analysis of communication overhead and computational complexity metrics shows the efficiency of the proposed scheme.

关键词： Multi-server architecture Authenticated key agreement Registration server One-way hash function Key compromise impersonation

Numerical Study of Natural Convection in an Inclined Porous Cavity

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Fluid Dynamics & Materials Processing 2022年第5期18卷 1389-1397页

作者： saad Adjal Sabiha Aklouche-Benouaguef Belkacem Zeghmati Laboratoire des Transports Polyphasiques et Milieux Poreux LTPMPALGER16111ALGERIE Laboratoire des Mathématiques et Physique des Systèmes LAMPSPerpignan66860France

Two-dimensional transient laminar natural convection in a square cavity containing a porous medium and inclined at an angle of 30°is investigated *** vertical walls are differentially heated,and the horizontal walls are *** effect of Rayleigh number on heat transfer and on the road to chaos is *** natural heat transfer and the Darcy Brinkman equations are solved by using a finite volume method and a Tri Diagonal Matrix Algorithm(TDMA).The results are obtained for a porosity equal to 0.45,a Darcy number and a Prandtl respectively equal to 10^(-3)and 0.71;they are analyzed in terms of streamlines,isotherms,phase portrait,attractors,and spectra amplitude as a function of the Rayleigh *** is found that,as Rayleigh number increases,the natural convection changes from a steady state to a time-periodic state and finally to a chaotic condition.

关键词： Natural convection porous medium finite volumes chaos attractors

Effect of Co on Solidification Characteristics and Microstructural Transformation of Non-equilibrium Solidified Cu-Ni Alloys

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Journal of Wuhan University of Technology(Materials Science) 2024年第2期39卷 444-453页

作者：安红恩 Bih-Lii Chua Ismail saad Willey Yun Hsien Liew Materials Engineering Research Group Faculty of EngineeringUniversity Malaysia Sabah88400 Kota KinabaluSabahMalaysia College of Mechanical and Electronic Engineering Huanghe Jiaotong UniversityJiaozuo 454950China Henan Engineering Technology Research Center on Intelligent Manufacturing Technology and Equipment Jiaozuo 454950China Centre of Research in Energy and Advanced Materials Faculty of EngineeringUniversiti Malaysia SabahJalan UMS88400 Kota KinabaluSabahMalaysia Nano Engineering and Materials Research group Faculty of EngineeringUniversity Malaysia Sabah88400 Kota KinabaluSabahMalaysia

Non-equilibrium solidification structures of Cu55Ni45 and Cu55Ni43Co2 alloys were prepared by the molten glass purification cycle superheating *** variation of the recalescence phenomenon with the degree of undercooling in the rapid solidification process was investigated using an infrared *** addition of the Co element affected the evolution of the recalescence phenomenon in Cu-Ni *** images of the solid-liquid interface migration during the rapid solidification of supercooled melts were captured by using a high-speed *** solidification rate of Cu-Ni alloys,with the addition of Co elements,was ***,the grain refinement structure with low supercooling was characterised using electron backscatter diffraction(EBSD).The effect of Co on the microstructural evolution during nonequilibrium solidification of Cu-Ni alloys under conditions of small supercooling is investigated by comparing the microstructures of Cu55Ni45 and Cu55Ni43Co2 *** experimental results show that the addition of a small amount of Co weakens the recalescence behaviour of the Cu55Ni45 alloy and significantly reduces the thermal strain in the rapid solidification *** the rapid solidification phase,the thermal strain is greatly reduced,and there is a significant increase in the characteristic undercooling ***,the addition of Co and the reduction of Cu not only result in a lower solidification rate of the alloy,but also contribute to the homogenisation of the grain size.

关键词： non-equilibrium solidification recalescence effect solidification character microstructure

Dynamical analysis and anti-synchronization of a new 6D model with self-excited attractors

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Applied Mathematics(A Journal of Chinese Universities) 2023年第1期38卷 27-43页

作者： saad Fawzi Al-Azzawi Ahmed S.Al-Obeidi Department of Mathematics College of Computer Science and MathematicsUniversity of MosulMosul 41002Iraq

A novel 6D dissipative model with an unstable equilibrium point is introduced *** of the dynamic characteristics of the proposed model were explored via analyses and numerical simulations including critical points,stability,Lyapunov exponents,time phase portraits,and circuit ***,anti-synchronization phenomena were implemented on the new ***,the error dynamics is ***,four different controllers are adopted to stabilize this error relying on the nonlinear control technique with two main ways:linearization and Lyapunov stability *** comparison with previous works,the present controllers realize anti-synchronization based on another method/linearization ***,a comparison between the two ways was *** simulation results show the effectiveness and accuracy of the first analytical strategy.

关键词： 6D hyperchaotic system self-excited attractor anti-synchronization Lyapunov stability theory

Methods for in vitro evaluating antimicrobial activity： A review

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Journal of Pharmaceutical Analysis 2016年第2期6卷 71-79页

作者： mounyr balouiri moulay sadiki saad koraichi ibnsouda Laboratory of Microbial Biotechnology Faculty of Sciences and Techniques University Sidi Mohamed Ben Abdellah B.P.. 2202 lmouzzer Road Fez Morocco

In recent years, there has been a growing interest in researching and developing new antimicrobial agents from various sources to combat microbial resistance. Therefore, a greater attention has been paid to antimicrobial activity screening and evaluating methods. Several bioassays such as disk-diffusion, well diffusion and broth or agar dilution are well known and commonly used, but others such as flow cy- tofluorometric and bioluminescent methods are not widely used because they require specified equip- ment and further evaluation for reproducibility and standardization, even if they can provide rapid re- sults of the antimicrobial agent＇s effects and a better understanding of their impact on the viability and cell damage inflicted to the tested microorganism. In this review article, an exhaustive list of in vitro antimicrobial susceptibility testing methods and detailed information on their advantages and limita- tions are reported.

关键词： Thin-layer chromatography (TLC)-bioautography Time-kill test Antimicrobial gradient method Agar diffusion method

Recognition of motor imagery tasks for BCI using CSP and chaotic PSO twin SVM

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The Journal of China Universities of Posts and Telecommunications 2017年第3期24卷 83-90页

作者： Li Duan Zhang Hongxin Muhammad saad Khan Mi Fang School of Electronic Engineering Beijing University of Posts and Telecommunications School of Physics and Electronic Information Engineering Henan Polytechnic University

Accurate modeling and recognition of the brain activity patterns for reliable communication and interaction are still a challenging task for the motor imagery （MI） brain-computer interface （BCI） system. In this paper, we propose a common spatial pattern （CSP） and chaotic particle swarm optimization （CPSO） twin support vector machine （TWSVM） scheme for classification of MI electroencephalography （EEG）. The self-adaptive artifact removal and CSP were used to obtain the most distinguishable features. To improve the recognition results, CPSO was employed to tune the hyper-parameters of the TWSVM classifier. The usefulness of the proposed method was evaluated using the BCI competition IV-IIa dataset. The experimental results showed that the mean recognition accuracy of our proposed method was increased by 5.35%, 4.33%, 0.78%, 1.45%, and 9.26% compared with the CPSO support vector machine （SVM）, particle swarm optimization （PSO） TWSVM, linear discriminant analysis （LDA）, back propagation （BP） and probabilistic neural network （PNN）, respectively. Furthermore, it achieved a faster or comparable central processing unit （CPU） running time over the traditional SVM methods.

关键词： brain-computer interface motor imagery twin support vector machine chaotic particle swarm optimization