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Time-delay effect and design of closed-loop control system of circulation control airfoil

Chinese Journal of Aeronautics 2024年第10期37卷 50-67页

作者： Lingxiao Li Heyong XU Zheng XING abdul Samad khan School of Aeronautics Northwestern Polytechnical UniversityXi’an 710072China National Key Laboratory of Aircraft Configuration Design Xi’an 710072China

In this paper,unsteady numerical simulation of jet Circulation Control(CC)is carried out with the NACA0012-CC airfoil as the research *** dynamic process from the opening of jet slot and adjustment of jet intensity to the stable state of jet control effect is *** time-delay effect and flow mechanism of jet are *** mechanism of jet momentum coefficient and moment coefficient fluctuating with time is *** fluctuation of jet momentum coefficient is caused by the change of the pressure coefficient distribution on the Coanda surface or the structure of the wave system inside the jet,and the oscillation frequency of the wave system structure of the under-expansion supersonic jet reaches 1481 Hz at the opening *** on the aerodynamic model and Proportional-Integral-Derivative(PID)control theory,the closed-loop control system of CC airfoil is *** parameters of PID control system are adjusted by the Genetic Algorithm(GA),which significantly improves the response ability of the control system to step,ramp and sine signals,and improves the dynamic performance of the *** at the special time-delay effect of jet control,Long Short-Term Memory(LSTM)neural network module is added to the control system to predict the target input signal,which strengthens the prediction ability of GA-PID control system to the target signal at the next time *** using LSTM neural network correction,the control hysteresis caused by jet time-delay effect is alleviated,and the response ability of the control system is effectively ***,the designed LSTM-GA-PID control system is applied to the NACA0012-CC airfoil for the pitch control simulation *** test results show that the control system designed in this paper has good dynamic performance and can respond quickly and accurately to complex input signals,which confirms the effectiveness of the control system.

关键词： Circulation control Unsteady numerical simulation Time-delay effect Control system Long short-term memory

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3D Printing with a 5-Axis FDM Printer Using Bézier Techniques

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Transactions of Nanjing University of Aeronautics and Astronautics 2024年第S1期41卷 13-20页

作者： khan abdul Basit WANG Xiaoping College of Mechanical and Electrical Engineering Nanjing University of Aeronautics and AstronauticsNanjing 210016P.R.China

In the last decade,3D printing,especially fused deposition modeling(FDM),has revolutionized manufacturing with intricate *** 3-axis FDM printers face challenges with complex geometries,but 5-axis versions offer more design ***,it requires specialized *** research presents a model for 5-axis FDM printers using Bézier curves with an algorithm to enhance print *** result shows significant accuracy improvements,especially for curve-based *** addition,this study deepens the understanding of 5-axis FDM technology,setting a solid basis for further research and potentially refining manufacturing methods.

关键词： additive manufacturing fused deposition modeling(FDM) slicing algorithms surface quality optimization

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Autologous hematopoietic stem cell transplantation conditioning regimens and chimeric antigen receptor T cell therapy in various diseases

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World Journal of Transplantation 2024年第1期14卷 32-41页

作者： Shahzaib Maqbool Maryam Farhan Baloch Muhammad abdul Khaliq khan Azeem Khalid Kiran Naimat Department of Medicine Holy Family HospitalRawalpindi 46000Pakistan Department of Community Medicine Allama Iqbal Medical CollegeLahore 45000Pakistan Department of Community Dentistry Baqai Medical UniversityKarachi 43000Pakistan Department of Medicine Allama lqbal Medical CollegeLahore 45000Pakistan Department of MedicineLiaquat University of Medical and Health Sciences Karachi 43000Pakistan

Conditioning regimens employed in autologous stem cell transplantation have been proven useful in various hematological disorders and underlying malignancies;however,despite being efficacious in various instances,negative consequences have also been *** conditioning regimens were extracted from various literature searches from databases like PubMed,Google scholar,EMBASE,and *** regimens for each disease were compared by using various end points such as overall survival(OS),progression free survival(PFS),and leukemia free survival(LFS).Variables were presented on graphs and analyzed to conclude a more efficacious conditioning *** multiple myeloma,the most effective regimen was high dose melphalan(MEL)given at a dose of 200/mg/*** comparative results of acute myeloid leukemia were presented and the regimens that proved to be at an admirable position were busulfan(BU)+MEL regarding OS and BU+VP16 regarding *** case of acute lymphoblastic leukemia(ALL),BU,fludarabine,and etoposide(BuFluVP)conferred good disease control not only with a paramount improvement in survival rate but also low risk of ***,for ALL,chimeric antigen receptor(CAR)T cell therapy was preferred in the context of better OS and *** respect to Hodgkin’s lymphoma,mitoxantrone(MITO)/MEL overtook carmustine,VP16,cytarabine,and MEL in view of PFS and vice versa regarding ***-Hodgkin’s lymphoma patients were administered MITO(60 mg/m2)and MEL(180 mg/m2)which showed promising ***,amyloidosis was considered,and the regimen that proved to be competent was MEL 200(200 mg/m2).This review article demonstrates a comparison between various conditioning regimens employed in different diseases.

关键词： Conditioning regimens Multiple myeloma Lymphoma Hodgkin Non-Hodgkin Acute leukemia

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Malaysia-China Relations:Exemplary Model for ASEAN

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China Report ASEAN 2024年第6期9卷 48-51页

作者： Dato'abdul Majid Ahmad khan Malaysia-China Friendship Association

Five Decades(1974-2024)of Harmonious and Mutually Beneficial Partnership Fifty years ago in May 1974,the second Prime Minister of Malaysia,Tun abdul Razak,journeyed to Beijing,China,to start a new and strategic chapter in Malaysia-China *** was a visionary and courageous initiative by Malaysia that commenced resetting Malaysia's foreign policy towards non-alignment and building mutual trust with China.

关键词： Malaysia mutual policy

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MODELING DAM-BREAK FLOOD OVER NATURAL RIVERS USING DISCONTINUOUS GALERKIN METHOD

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Journal of Hydrodynamics 2012年第4期24卷 467-478页

作者： khan abdul A. Glenn Department of Civil Engineering Clemson University

A well-balanced numerical model is presented for two-dimensional, depth-averaged, shallow water flows based on the Discontinuous Galerkin （DG） method. The model is applied to simulate dam-break flood in natural rivers with wet/dry bed and complex topography. To eliminate numerical imbalance, the pressure force and bed slope terms are combined in the shallow water flow equations. For partially wet/dry elements, a treatment of the source term that preserves the well-balanced property is presented. A treatment for modeling flow over initially dry bed is presented. Numerical results show that the time step used is related to the dry bed criterion. The intercell numerical flux in the DG method is computed by the Harten-Lax-van Contact （HLLC） approximate Riemann solver. A two-dimensional slope limiting procedure is employed to prevent spurious oscillation. The robustness and accuracy of the model are demonstrated through several test cases, including dam-break flow in a channel with three bumps, laboratory dam-break tests over a triangular bump and an L-shape bend, dam-break flood in the Paute River, and the Malpasset dam-break case. Numerical results show that the model is robust and accurate to simulate dam-break flood over natural rivers with complex geometry and wet/dry beds.

关键词： Discontinuous Galerkin (DG) method shallow water flows dam-break flood well-balanced scheme

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Systematic Geometric Error Modeling for Workspace Volumetric Calibration of a 5-axis Turbine Blade Grinding Machine

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Chinese Journal of Aeronautics 2010年第5期23卷 604-615页

作者： abdul Wahid khan School of Mechanical Engineering and Automation Beijing University of Aeronautics and Astronautics

A systematic geometric model has been presented for calibration of a newly designed 5-axis turbine blade grinding machine. This machine is designed to serve a specific purpose to attain high accuracy and high efficiency grinding of turbine blades by eliminating the hand grinding process. Although its topology is RPPPR （P： prismatic; R： rotary）, its design is quite distinct from the competitive machine tools. As error quantification is the only way to investigate, maintain and improve its accuracy, calibra- tion is recommended for its performance assessment and acceptance testing. Systematic geometric error modeling technique is implemented and 52 position dependent and position independent errors are identified while considering the machine as five rigid bodies by eliminating the set-up errors of workpiece and cutting tool. 39 of them are found to have influential errors and are accommodated for finding the resultant effect between the cutting tool and the workpiece in workspace volume. Rigid body kinematics techniques and homogenous transformation matrices are used for error synthesis.

关键词： 5-axis machine tools calibration modeling geometric errors kinematics homogenous transformation matrices

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Time stepping in discontinuous Galerkin method

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Journal of Hydrodynamics 2013年第3期25卷 321-329页

作者： LAI Wencong khan abdul A Glenn Department of Civil Engineering Clemson University Clemson S.C. USA

The time discretization in the Discontinuous Galerkin （DG） scheme has been traditionally based on the Total Variation Diminishing （TVD） second-order Runge-Kutta （RK2） scheme. Computational efficiency and accuracy with the Euler Forward （EF） and the TVD second-order RK2 time stepping schemes in the DG method are investigated in this work. Numerical tests are condu- cted with the scalar Burgers equation, 1-D and 2-D shallow water flow equations. The maximum Courant number or time step size required for stability for the EF scheme and RK2 scheme with different slope limiters are compared. Numerical results show that the slope limiters affect the stability requirement in the DG method. The RK2 scheme is generally more diffusive than the EF scheme, and the RK2 scheme allows larger time step sizes. The EF scheme is found to be more efficient and accurate than the RK2 scheme in the DG method in computation.

关键词： Discontinuous Galerkin (DG) method Euler Forward (EF) scheme second-order Runge-Kutta scheme

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Numerical solution of the Saint-Venant equations by an efficient hybrid finite-volume/finite-difference method

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Journal of Hydrodynamics 2018年第2期30卷 189-202页

作者： Wencong Lai abdul A.khan Glenn Department of Civil Engineering Clemson University

A computationally efficient hybrid finite-volume/finite-difference method is proposed for the numerical solution of SaintVenant equations in one-dimensional open channel flows. The method adopts a mass-conservative finite volume discretization for the continuity equation and a semi-implicit finite difference discretization for the dynamic-wave momentum equation. The spatial discretization of the convective flux term in the momentum equation employs an upwind scheme and the water-surface gradient term is discretized using three different schemes. The performance of the numerical method is investigated in terms of efficiency and accuracy using various examples, including steady flow over a bump, dam-break flow over wet and dry downstream channels, wetting and drying in a parabolic bowl, and dam-break floods in laboratory physical models. Numerical solutions from the hybrid method are compared with solutions from a finite volume method along with analytic solutions or experimental measurements. Comparisons demonstrates that the hybrid method is efficient, accurate, and robust in modeling various flow scenarios, including subcritical, supercritical, and transcritical flows. In this method, the QUICK scheme for the surface slope discretization is more accurate and less diffusive than the center difference and the weighted average schemes.

关键词： Hybrid numerical method Saint-Venant equations shallow water flow

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Biodiesel synthesis via metal oxides and metal chlorides catalysis from marine alga Melanothamnus afaqhusainii

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Chinese Journal of Chemical Engineering 2016年第3期24卷 388-393页

作者： abdul Majeed khan Noureen Fatima Research Laboratory of Bioenergy Department of ChemistryFederal Urdu University of ArtsSdence and TechnologyCulshan-e-lqbal CampusUniversity RoadKarachi-75300Pakistan

This research article demonstrates the most comprehensive comparative catalytic study of different metal oxides and metal chlorides towards the methanolysis of triglycerides of marine red macroalga Melanothamnus alhqhusainii. CaO was found to be the most reactive metal oxide that yielded 80% biodiesel while ZnCI2 was the most reactive metal chloride that produced 60% biodiesel by mechanical stirring for 6 h at 100-110 ℃. The overall reactivity order of the catalysts was found to be CaO 〉 MgO 〉 Pb02 〉 ZnC12 〉 TIC14 〉 PbO 〉 HgC12 〉 ZnO 〉 AIC13 〉 SnCI2 〉 TiO2 whereas, CaCI2, MgCI2, A1203, HgO, PbCI2, MnO2, MnC12, Fe203 and FeCI3 were found to be non-reactive for transesterification of triglycerides. In addition, a detailed study of the screening of mobile phases and spraying reagents was conducted which showed that petroleum ether ： chloroform ： toluene （7：2：1 ） is the best mobile phase, whereas iodine crystals/silica gel is the best visualizing agent for the thin layer chroma- tography （TLC） examination ofbiodiesel. Biodiesel production was confirmed by comparative TLC examination. It was further supported by the determination of fuel properties of biodiesel, which were found to be similar to the standard limits of American Society for Testing and Materials （ASTM）,

关键词： Biomass Methanolysis Triglycerides Biodiesel Catalysts

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1-D coupled non-equilibrium sediment transport modeling for unsteady flows in the discontinuous Galerkin framework

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Journal of Hydrodynamics 2016年第4期28卷 534-543页

作者： Farzam Safarzadeh MALEKI abdul A.khan Engineering Department Massachusetts Maritime Academy Glenn Department of Civil Engineering Clemson University

A high-resolution, 1-D numerical model has been developed in the discontinuous Galerkin framework to simulate 1-D flow behavior, sediment transport, and morphological evaluation under unsteady flow conditions. The flow and sediment concentration variables are computed based on the one-dimensional shallow water flow equations, while empirical equations are used for entrainment and deposition processes. The sediment transport model includes the bed load and suspended load components. New formulations for Harten-Lax-van Leer （HLL） and Harten-Lax-van Contact （HLLC） are presented for shallow water flow equations that include the bed load and suspended load fluxes. The computational results for the flow and morphological changes after two dam break events are compared with the physical model tests. Results show that the modified HLL and HLLC formulations are robust and can accurately predict morphological changes in highly unsteady flows.

关键词： dam break flow sediment transport modeling Harten-Lax-van Leer (HLL) and Harten-Lax-van Contact (HLLC) fluxfunctions discontinuous Galerkin scheme

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