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Micro-fabrication of ceramics:Additive manufacturing and conventional technologies

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Journal of Advanced Ceramics 2021年第1期10卷 1-27页

作者： hany hASSANIN Khamis ESSA Amr ELShAER Mohamed IMBABY heba h.EL-MONGY Tamer A.EL-sayed School of Engineering Canterbury Christ Church UniversityCanterburyCT11QUUK University of Birmingham EdgbastonB152TTUK Kingston University London Penrhyn RoadKingston Upon ThamesSurreyKT12EEUK Department of Mechanical Design Faculty of EngineeringMatariaHelwan UniversityP.O.Box.11718CairoEgypt Jubail University College Mechanical EngineeringKingdom of Saudi Arabia Center for Applied Dynamics Research(CADR) School of EngineeringUniversity of AberdeenAberdeenAB243UEUK

Ceramic materials are increasingly used in micro-electro-mechanical systems(MEMS)as they offer many advantages such as high-temperature resistance,high wear resistance,low density,and favourable mechanical and chemical properties at elevated ***,with the emerging of additive manufacturing,the use of ceramics for functional and structural MEMS raises new opportunities and *** paper provides an extensive review of the manufacturing processes used for ceramic-based MEMS,including additive and conventional manufacturing *** review covers the micro-fabrication techniques of ceramics with the focus on their operating principles,main features,and processed *** that need to be addressed in applying additive technologies in MEMS include ceramic printing on wafers,post-processing at the micro-level,resolution,and quality *** paper also sheds light on the new possibilities of ceramic additive micro-fabrication and their potential applications,which indicates a promising future.

关键词： micro-electro-mechanical system(MEMS) micro-fabrication ceramics micro parts additive manufacturing

Simulation of the response of base-isolated buildings under earthquake excitations considering soil flexibility

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Earthquake Engineering and Engineering Vibration 2012年第3期11卷 359-374页

作者： sayed Mahmoud Per-Erik Austrell Robert Jankowski Department of Construction Sciences Division of Structural MechanicsLund University Faculty of Engineering at Mataria Helwan University Faculty of Civil and Environmental Engineering Gdansk University of Technology

The accurate analysis of the seismic response of isolated structures requires incorporation of the flexibility of supporting soil. however, it is often customary to idealize the soil as rigid during the analysis of such structures. In this paper, seismic response time history analyses of base-isolated buildings modelled as linear single degree-of-freedom （SDOF） and multi degree-of-freedom （MDOF） systems with linear and nonlinear base models considering and ignoring the flexibility of supporting soil are conducted. The flexibility of supporting soil is modelled through a lumped parameter model consisting of swaying and rocking spring-dashpots. In the analysis, a large number of parametric studies for different earthquake excitations with three different peak ground acceleration （PGA） levels, different natural periods of the building models, and different shear wave velocities in the soil are considered. For the isolation system, laminated rubber bearings （LRBs） as well as high damping rubber bearings （hDRBs） are used. Responses of the isolated buildings with and without SSI are compared under different ground motions leading to the following conclusions：（1） soil flexibility may considerably influence the stiff superstructure response and may only slightly influence the response of the flexible structures; （2） the use of hDRBs for the isolation system induces higher structural peak responses with SSI compared to the system with LRBs; （3） although the peak response is affected by the incorporation of soil flexibility, it appears insensitive to the variation of shear wave velocity in the soil; （4） the response amplifications of the SDOF system become closer to unit with the increase in the natural period of the building, indicating an inverse relationship between SSI effects and natural periods for all the considered ground motions, base isolations and shear wave velocities; （5） the incorporation of SSI increases the number of significant cycles of large amplitude acce

关键词： base-isolated buildings rubber bearings earthquakes soil-structure interaction

Weibel Instability Growth Rate in Magnetized Plasmas with Quasi-Relativistic Distribution Function

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Communications in Theoretical Physics 2016年第12期65卷 709-712页

作者： sayed Ahmad hosseini Mohammad Mahdavi Physics Department University of Mazandaran

The mechanism of the Weibel instability is investigated for dense magnetized plasmas. As we know, due to the electron velocity distribution, the Coulomb collision effect of electron-ion and the relativistic properties play an important role in such study. In this study an analytical expression for the growth rate and the condition of restricting the Weibel instability are derived for low-frequency limit. These calculations are done for the oscillation frequency dependence on the electron cyclotron frequency. It is shown that, the relativistic properties of the particle lead to increasing the growth rate of the instability. On the other hand the collision effects and background magnetic field try to decrease the growth rate by decreasing the temperature anisotropy and restricting the particles movement.

关键词： background Weibel instability coulomb collision growth rate quasi-Maxwellian

Post-synthetic metalation of organic cage for enhanced porosity and catalytic performance

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Science China Chemistry 2023年第6期66卷 1763-1770页

作者： Miao Yang Xun Chen Yifei Xie El-sayed MEl-sayed Ning Xu Wenjing Wang Kongzhao Su Daqiang Yuan State Key Lab of Structure Chemistry Fujian Institute of Research on the Structure of MatterChinese Academy of SciencesFuzhou 350002China University of the Chinese Academy of Sciences Beijing 100049China College of Chemistry Fuzhou UniversityFuzhou 310116China Chemical Refining Laboratory Refining DepartmentEgyptian Petroleum Research InstituteNasr City 11727Egypt

Porous organic cages(POCs)have shown great potential in many applications,and post-synthetic modification(PSM)has been confirmed to be an effective strategy to tailor their structures and related ***,it is extremely challenging to develop a general platform for simple-to-make functional POCs for advanced applications by PSM ***,we reported that octahedral calix[4]resorcinarene-based hydrazone-linked porous organic cage(hPOC-401)provides an excellent platform for post-synthetic metalation by various transition metal(TM)ions under mild conditions due to the abundance of coordination sites in its *** metalated products(hPOC-401-TM)exhibit Brunauer-Emmett-Teller(BET)surface area up to1,456 m^(2)g^(-1),much higher than that of the pristine hPOC-401,which has a BET value of 474 m^(2)g^(-1).Moreover,the metalation and porosity increases further influence their gas capture,separation,as well as catalytic *** instance,hPOC-401-TM products exhibit higher CO_(2),h_(2),and C2 hydrocarbon gas uptake,as well as higher C_(2)h_(6)/C_(2)h_(4) selectivity than ***,the hPOC-401-TM also shows better catalytic performance in the cycloaddition of CO_(2) with epoxides compared to *** findings uncover a simple yet effective approach for modifying the porosity characteristics of organic cages,which will undoubtedly expand their future implementations.

关键词： porous organic cage(POC) calixresorcinarene post-synthetic metalation(PSM) gas adsorption and separation CO_(2)cycloaddition

Position Control of Synchronous Motor Drive by Modified Adaptive Two-phase Sliding Mode Controller

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International Journal of Automation and computing 2008年第4期5卷 406-412页

作者： Mohamed Said sayed Ahmed Automation Science and Electrical Engineering School Beijing University of Aeronautics and Astronautics

A modified adaptive two-phase sliding mode controller for the synchronous motor drive that is highly robust to uncertain- ties and external disturbances is proposed in this *** proposed controller uses two-phase sliding mode control (SMC) where the 1st phase mainly controls the system in steady states and disturbed states-it is a smoothing *** 2nd phase is used mainly in the case of disturbed ***,it is an autotuning phase and uses a simple adaptive algorithm to tune the gain of conventional variable structure control (VSC).The modified controller is useful in position control of a permanent magnet synchronous drive.

关键词： Reaching law adaptive control sliding mode control (SMC) chattering.

Control of UPQC Based on Steady State Linear Kalman Filter for Compensation of Power Quality Problems

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Chinese Journal of Electrical Engineering 2020年第2期6卷 52-65页

作者： sayed Javed Alam Sabha Raj Arya Department of Electrical Engineering Sardar Vallabhai National Institute of TechnologySuart 395007India

A frequency lock loop(FLL)based steady state linear Kalman filter(SSLKF)for unified power quality conditioner(UPQC)control in three-phase systems is *** SSLKF provides a highly accurate and fast estimation of grid frequency and the fundamental components(FCs)of the input *** Kalman filter is designed using an optimized filtering technique and intrinsic adaptive bandwidth architecture,and is easily integrated into a multiple model ***,the Kalman state estimator is fast and *** fundamental positive sequence components(FPSCs)of the grid voltages in a UPQC system are estimated via these SSLKF-FLL based *** estimation of reference signals for a UPQC controller is based on these ***,both active filters of a UPQC can perform one and more functions towards improving power quality in a distribution *** addition to the SSLKF-FLL based algorithm,a bat optimization algorithm(based on the echolocation phenomenon of bats)is implemented to estimate the value of the proportional integral(PI)controller *** bat algorithm has a tendency to automatically zoom into a region where a promising alternative solution occurs,preventing the solution from becoming trapped in a local *** complete three-phase UPQC is simulated in the Matlab/Simulink platform and the hardware is tested under various power quality problems.

关键词： Damping factor echo-location FPSC harmonics ITSE SSLKF-FLL power quality

Seeker Optimization with Deep Learning Enabled Sentiment Analysis on Social Media;

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Computers, Materials & Continua 2022年第12期73卷 5985-5999页

作者： hanan M.Alghamdi Saadia h.A.hamza Aisha M.Mashraqi sayed Abdel-Khalek Department of Computer Science College of Computing Al-QunfidhahUmm Al-Qura UniversitySaudi Arabia Department of Computer Science College of Science and HumanitiesSlayelPrince Sattam Bin AbdulAziz UniversitySaudi Arabia Department of Computer Science College of Computer Science and Information SystemsNajran UnivesityNajran61441Saudi Arabia Department of Mathematics College of ScienceTaif UniversityP.O.Box 11099Taif21944Saudi Arabia Department of Mathematics Faculty of ScienceSohag UniversitySohagEgypt

World Wide Web enables its users to connect among themselves through social networks,forums,review sites,and blogs and these interactions produce huge volumes of data in various forms such as emotions,sentiments,views,*** Analysis(SA)is a text organization approach that is applied to categorize the sentiments under distinct classes such as positive,negative,and ***,Sentiment Analysis is challenging to perform due to inadequate volume of labeled data in the domain of Natural Language Processing(NLP).Social networks produce interconnected and huge data which brings complexity in terms of expanding SA to an extensive array of ***,there is a need exists to develop a proper technique for both identification and classification of sentiments in social *** get rid of these problems,Deep Learning methods and sentiment analysis are consolidated since the former is highly efficient owing to its automatic learning *** current study introduces a Seeker Optimization Algorithm with Deep Learning enabled SA and Classification(SOADL-SAC)for social *** presented SOADL-SAC model involves the proper identification and classification of sentiments in social *** order to attain this,SOADL-SAC model carries out data preprocessing to clean the input *** addition,Glove technique is applied to generate the feature ***,Self-head Multi-Attention based Gated Recurrent Unit(ShMA-GRU)model is exploited to recognize and classify the ***,Seeker Optimization Algorithm(SOA)is applied to fine-tune the hyperparameters involved in ShMA-GRU model which in turn enhances the classifier *** order to validate the enhanced outcomes of the proposed SOADL-SAC model,various experiments were conducted on benchmark *** experimental results inferred the better performance of SOADLSAC model over recent state-of-the-art approaches.

关键词： Sentiment analysis classification of sentiment social media seeker optimization algorithm glove embedding natural language processing

A NEW hYBRIDIZED MIXED WEAK GALERKIN METhOD FOR SECOND-ORDER ELLIPTIC PROBLEMS

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Journal of Computational Mathematics 2022年第4期40卷 499-516页

作者： Abdelhamid Zaghdani sayed Sayari Miled EL hajji University of Tunis Boulevard du 9 avril 1939 TunisDepartment of MathematicsEnsitTaha Hussein AvenueMontfleuryTunisTunisia Northern Border University Faculty of Arts and ScienceRafhaP.O.840Saudi Arabia Carthage University Isteub2 Rue de l’Artisanat Charguia 22035 TunisTunisia Department of Mathematics Faculty of SciencesUniversity of JeddahSaudi Arabia ENIT-LAMSINBP.371002 Tunis-Belv´ed`ereTunis El Manar UniversityTunisia

In this paper,a new hybridized mixed formulation of weak Galerkin method is studied for a second order elliptic *** method is designed by approximate some operators with discontinuous piecewise polynomials in a shape regular finite element *** discrete inequalities are presented on discontinuous spaces and optimal order error estimations are *** numerical results are reported to show super convergence and confirm the theory of the mixed weak Galerkin method.

关键词： Weak Galerkin Weak gradient hybridized mixed finite element method Second order elliptic problems

Split-n-Swap: A New Modification of the Twofish Block Cipher Algorithm

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Computers, Materials & Continua 2023年第1期74卷 1723-1734页

作者： Awny sayed Maha Mahrous Enas Elgeldawi Computer Science Department Faculty of ScienceMinia UniversityMinia61519Egypt Faculty of Computing and Information Technology Information Technology DepartmentKing Abdulaziz UniversityJeddah21589Saudi Arabia Computer Science Department Faculty of Computers and InformationMinia UniversityMinia61519Egypt

Securing digital data from unauthorized access throughout its entire lifecycle has been always a critical concern.A robust data security system should protect the information assets of any organization against cybercriminal *** Twofish algorithm is one of the well-known symmetric key block cipher cryptographic algorithms and has been known for its rapid *** when it comes to security,it is not the preferred cryptographic algorithm to use compared to other algorithms that have shown better *** applications and social platforms have adopted other symmetric key block cipher cryptographic algorithms such as the Advanced Encryption Standard(AES)algorithm to construct their main security *** this paper,a new modification for the original Twofish algorithm is proposed to strengthen its security and to take advantage of its fast *** new algorithm has been named Split-n-Swap(SnS).Performance analysis of the new modification algorithm has been performed using different measurement *** experimental results show that the complexity of the SnS algorithm exceeds that of the original Twofish algorithm while maintaining reasonable values for encryption and decryption times as well as memory utilization.A detailed analysis is given with the strength and limitation aspects of the proposed algorithm.

关键词： Twofish advanced encryption standard(AES) cryptography symmetric key block cipher