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Multidisciplinary design optimization of a dual-spin guided vehicle

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Defence Technology（防务技术） 2024年第7期37卷 133-148页

作者： Jalal Karimi Mohammad Reza rajabi Seyed Hossein Sadati Seyed Mahid Hosseini Department of Aerospace Engineering Malek Ashtar University of TechnologyTehranIran

In this research,a Multidisciplinary Design Optimization approach is proposed for the dual-spin guided flying projectile design considering external and internal parts of the body as design *** this way,a parametric formulation is *** related disciplines,including structure,aerodynamics,guidance,and control are *** total mass,maximum aerodynamic control effectiveness,minimum miss distance,maximum yield stress in all subsystems,controllability and gyroscopic stability constraints are some of objectives/constraints taken into *** problem is formulated in All-At-Ones Multidisciplinary Design Optimization approach structure and solved by Simulated Annealing and minimax *** optimal configurations are evaluated in various *** resulted optimal configurations have met all design objectives and constraints.

关键词： Flying projectile optimal design All-at-ones multidisciplinary optimization Structure discipline Guidance and control discipline Aerodynamic discipline

Using neural network modeling to improve the detection accuracy of land subsidence due to groundwater withdrawal

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Journal of Mountain Science 2024年第7期21卷 2320-2333页

作者： Ali M.rajabi Ali EDALAT Yasaman ABOLGHASEMI Mahdi KHODAPARAST Department of Engineering Geology University of TehranTehran ***Iran Department of Civil Engineering University of QomQom ***Iran

Despite the high efficiency of remote sensing methods for rapid and large-scale detection of subsidence phenomena,this technique has limitations such as atmospheric impact and temporal and spatial decorrelation that affect the accuracy of the *** paper proposes a method based on an artificial neural network to improve the results of monitoring land subsidence due to groundwater overexploitation by radar interferometry in the Aliabad plain(Central Iran).In this regard,vertical ground deformations were monitored over 18 months using the Sentinel-1A SAR *** model the land subsidence by a multilayer perceptron(MLP)artificial neural network,four parameters,including groundwater level,alluvial thickness,elastic modulus,and transmissivity have been *** model's generalizability was assessed using data derived for 144 *** to the results,the neural network estimates the land subsidence at each ground point with an accuracy of 6.8 mm.A comparison between the predicted and actual values indicated a significant *** MLP model can be used to improve the results of subsidence detection in the study area or other areas with similar characteristics.

关键词： DInSAR Land subsidence Groundwater withdrawal Aliabad plain Artificial neural network

挤压速度对搅拌摩擦反挤压法制备Cu-5%Ti_(2)SnC复合丝材性能的影响

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Transactions of Nonferrous Metals Society of China 2024年第3期34卷 935-951页

作者： Amirhossein JAHANI Hamed JAMSHIDI AVAL Mohammad rajabi Roohollah JAMAATI Department of Materials Engineering Babol Noshirvani University of TechnologyShariati AvenueBabol 47148-71167Iran

对粉末冶金法制备的含5%(体积分数)Ti_(2)Sn CMAX相的初始复合材料进行搅拌摩擦反挤压(FSBE)处理,研究FSBE工艺的轴向横移速度对Cu-Ti_(2)Sn C复合线材显微组织、力学性能、电学性能和磨损性能的影响。结果表明,随着挤压速度的增加,显... 详细信息

对粉末冶金法制备的含5%(体积分数)Ti_(2)Sn CMAX相的初始复合材料进行搅拌摩擦反挤压(FSBE)处理,研究FSBE工艺的轴向横移速度对Cu-Ti_(2)Sn C复合线材显微组织、力学性能、电学性能和磨损性能的影响。结果表明,随着挤压速度的增加,显微组织中孪晶增多,Ti_(2)SnC颗粒细化,MAX相和Cu基体之间的界面结合改善。当转速为600r/min,轴向横移速度为25mm/min时,Cu-Ti_(2)SnC复合线材具有最大的硬度、屈服强度和极限抗拉强度,分别为HV 132.7、278.34MPa和485.15MPa,这是其更强的界面结合和更细的MAX相导致的。此外,当转速为600 r/min,轴向横移速度为25 mm/min时,Cu-Ti_(2)SnC复合丝的电导率最高,达到89.21%(IACS),磨损率最低,为0.0015 mg/m,这是其更大的晶粒尺寸、更强的界面结合与更低的密度导致的。

关键词：搅拌摩擦反挤压 Ti_(2)SnC MAX相铜基复合材料电导率

Simulation of proppant transport at intersection of hydraulic fracture and natural fracture of wellbores using CFD-DEM

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Particuology 2022年第4期20卷 112-124页

作者： Siamak Akhshik Majid rajabi Department of Mechanical Engineering Sharif University of TechnologyIran Sustainable Manufacturing Research Laboratory School of Mechanical EngineeringIran University of Science and TechnologyIran

Proppants transport is an advanced technique to improve the hydraulic fracture phenomenon,in order to promote the versatility of gas/oil reservoirs.A numerical simulation of proppants transport at both hydraulic fracture(HF)and natural fracture(NF)intersection is performed to provide a better understand-ing of key factors which cause,or contribute to proppants transport in HF-NF *** fluid dynamics(CFD)in association with discrete element method(DEM)is used to model the complex interactions between proppant particles,host fluid medium and fractured *** effect of non-spherical geometry of particles is considered in this model,using the multi-sphere *** interaction forces between fluid flow and particles are considered in the computational ***,the inter-actions of particle-particle and particle-wall are taken into account via Hertz-Mindlin *** results of the CFD-DEM simulations are compared to the experimental *** is found that the CFD-DEM sim-ulation is capable of predicting proppant transport and deposition quality at intersections which are in agreement with experimental *** results indicate that the HF-NF intersection type,fluid velocity and NF aperture affect the quality of blockage occurrence,presenting a new index,called the blockage coefficient which indicates the severity of the blockage.

关键词： Hydraulic fracture process Proppants transport CFD-DEM method HF-NF intersection Blockage coffcient

The Role of Vanes in the Damping of Bird Feathers

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Journal of Bionic Engineering 2023年第4期20卷 1646-1655页

作者： Kai Deng Hamed rajabi Alexander Kovalev Clemens F.Schaber Zhendong Dai Stanislav N.Gorb Functional Morphology and Biomechanics Institute of ZoologyKiel University24098KielGermany School of Engineering London South Bank UniversityLondonSE10AAUK Institute of Bioinspired Structure and Surface Engineering Nanjing University of Aeronautics and AstronauticsNanjing210026People’s Republic of China

Bird feathers sustain bending and vibrations during *** unwanted vibrations could potentially cause noise and flight *** could alter the system response,resulting in improving quiet flight,stability,and *** of feathers are known to be indispensable for supporting the aerodynamic function of the *** relationship between the hierarchical structures of vanes and the mechanical properties of the feather has been previously ***,still little is known about their relationship with feathers’damping ***,the role of vanes in feathers’damping properties was *** vibrations of the feathers with vanes and the bare shaft without vanes after step deflections in the plane of the vanes and perpendicular to it were measured using high-speed video *** presence of several main natural vibration modes was observed in the feathers with *** trimming vanes,more vibration modes were observed,the fundamental frequencies increased by 51-70%,and the damping ratio decreased by 38-60%.Therefore,we suggest that vanes largely increase feather damping *** mechanisms based on the morphology of feather vanes are *** aerodynamic damping is connected with the planar vane surface,the structural damping is related to the interlocking between barbules and barbs,and the material damping is caused by the foamy medulla inside barbs.

关键词： Bird Feather Vibrations Damping Bionic

The frequency of wing damage in a migrating butterfly

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Insect Science 2023年第5期30卷 1507-1517页

作者： Rabiya Korkmaz Hamed rajabi Shahab Eshghi Stanislav N.Gorb Thies H.Büscher Department of Functional Morphology and Biomechanics Zoological InstituteKiel UniversityKielGermany Division of Mechanical Engineering and Design School of EngineeringLondon South Bank UniversityLondonUK

The ability to fly is crucial for migratory ***,the accumulation of damage on the wings over time can affect survival,especially for species that travel long *** examined the frequency of irreversible wing damage in the migratory butterfly Vanessa cardui to explore the effect of wing structure on wing damage frequency,as well as the mechanisms that might mitigate wing *** exceptionally high migration rate driven by high precipitation levels in their larval habitats in the winter of 2018–2019 provided us with an excellent opportunity to collect data on the frequency of naturally occurring wing damage associated with long-distance *** images of 135 individuals of *** were collected and analyzed in *** results show that the hindwings experienced a greater frequency of damage than the ***,forewings experienced more severe damage on the lateral margin,whereas hindwings experienced more damage on the trailing *** frequency of wing margin damage was higher in the painted lady butterfly than in the migrating monarch butterfly and in the butterfly Pontia occidentalis following artificially induced wing *** results of this study could be used in future comparative studies of patterns of wing damage in butterflies and other *** studies are needed to clarify whether the strategies for coping with wing damage differ between migratory and nonmigratory species.

关键词： biomechanics cost of migration flight Lepidoptera Vanessa cardui wing structure

Bound States for Hypercentral Singular and Exponential Potentials

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Communications in Theoretical Physics 2006年第4期45卷 669-674页

作者： A.A. rajabi Physics Department Shahrood University of Technology P.O. Box ***-316 Shahrood iran

With a view to obtaining an exact closed form solution to the Schr(o|¨)*** for a variety ofhypercentral potentials,we investigate further application of an *** method is good enough for many kinds ofpotentials,but in this article it applies to a type of the hypercentral singular potentials V(x)=ax~2+bx~(-4)+cx~(-6) andexponential hypercentral Morse potential U(x)=Uo(e~(-2ax)-2e~(-ax))for three interacting *** Morse potentialis used for diatomic molecule while this method will be successfully used for many atomic *** three-bodypotentials are more easily introduced and treated within the hyperspherical harmonic *** internal particlemotion is usually described by means of Jacobi relative coordinates p,λ,and R,in terms of three particle positions γ_1,γ_2,and γ_*** discuss some results obtained by using harmonic and anharmonic oscillators,however the hypercentralpotential can be easily generalized in order to allow a systematic analysis,which admits an exact solution of the *** method is also applied to some other types of three-body,four-body,...,interacting potentials.

关键词：超球面谐波不调和雅可比行列式拟设

A NONLINEAR MICROBEAM MODEL BASED ON STRAIN GRADIENT ELASTICITY THEORY

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Acta Mechanica Solida Sinica 2013年第1期26卷 21-34页

作者： Farshid rajabi Shojaa Ramezani Department of Mechanical Engineering Islamic Azad UniversityBandar Anzali BranchAnzaliIran Department of Mechanical Engineering Faculty of EngineeringUniversity of GuilanRashtIran

A micro scale nonlinear beam model based on strain gradient elasticity is developed. Governing equations of motion and boundary conditions are obtained in a variational framework. As an example, the nonlinear vibration of microbeams is analyzed. In a beam having a thickness to length parameter ratio close to unity, the strain gradient effect on increasing the natural frequency is predominant. By increasing the beam thickness, this effect decreases and geometric nonlinearity plays the main role on increasing the natural frequency. For some specific ratios, both geometric nonlinearity and size effects have a significant role on increasing the natural frequency.

关键词： strain gradient elasticity microbeam geometric nonlinearity

A Method to Solve the Schrdinger Equation for Any Power Hypercentral Potentials

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Communications in Theoretical Physics 2007年第7期48卷 151-158页

作者： A.A.rajabi Physics Department Shahrood University of TechnologyP.O.Box ***-316ShahroodIran

An exact closed form of solution to the hyperradial Schrdinger equation is constructed for any generalcase comprising any hypercentral power and inverse-power *** hypercentral potential depends only on thehyperradius,which itself is a function of Jacobi relative coordinates that are functions of particle positions(r_1,r_2,…...,r_N).This article is mainly devoted to the dernonstrat of the fact that any ψ of the form ψ=power series×exp(polynomial)=[f(x)exp(g(x))]is potentially a solution of the Schrdinger equation,where the polynomial g(x)is an ansatz dependingon the interaction potential.

关键词： power hypercenteral potential Shrdinger equation