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design and Robustness Analysis of a Wave-Based Controller for Tethered Towing of defunct Satellites

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IEEE/CAA Journal of Automatica Sinica 2023年第1期10卷 278-280页

作者： Rui Qi Yang Zhang Krishna d.kumar the School of Aerospace Engineering Beijing Institute of TechnologyBeijing 100081China IEEE the department of Aerospace Engineering Ryerson UniversityToronto M5B 2K3Canada

dear Editor, A microgravity environment in space, the elasticity of the tether,and complex flexible appendages make the tethered-towing system a nonlinear and underactuated system, which is sensitive and difficult to stabilize. This letter develops a controller based on wave propagation for tethered towing of defunct satellites, and carries out a robustness analysis of the controller via numerical simulation.

关键词： system elasticity letter

Mechanical and Corrosion Properties of Magnesiume-Hydroxyapatite (MgeHA) Composite Thin Films

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Journal of Materials Science & Technology 2013年第9期29卷 788-794页

作者： K.Mensah-darkwa R.K.Gupta d.kumar Engineering Research Center of Revolutionizing Metallic Biomaterials Department of Mechanical Engineering North Carolina A & T State University department of Chemistry Pittsburg State University

Magnesium(Mg)-hydroxyapatite(Ca10(PO4)6(OH)2,abbreviated as HA) composite films have been grown on Mg plates using a pulsed laser deposition *** property measurements and analysis have indicated that hardness and Young’s modulus of nMge(100e n)HA composite coatings increase with Mg content in the coatings and reach a maximum at a 70Mge 30HA composition.n and 100e n in the nMge(100e n)HA represent the relative number of laser pulses impinging on Mg and HA targets,*** current potentiodynamic polarization studies have shown that the corrosion of Mg plate(control) decreases with an increase in the HA ratio in the composite *** example,the corrosion current density of Mg plate reduces by w350 times after coating the Mg plate with 10Mge 90HA composite *** reduction in corrosion current density of Mg plates was also accompanied by a positive shift in the corrosion potential(w6%) due to this *** mechanism behind the reduction in corrosion behavior of Mg plates due to nMge(100e n) HA composite coatings has been understood by electrochemical impedance spectroscopy.

关键词： Magnesium Hydroxyapatite Scanning electron microscopy Pulsed laser deposition Corrosion Impedance spectroscopy

Corrosion Protective Conversion Coatings on Magnesium disks Using a Hydrothermal Technique

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Journal of Materials Science & Technology 2014年第1期30卷 47-53页

作者： R.K.Gupta K.Mensah-darkwa d.kumar department of Chemistry Pittsburg State University Engineering Research Center for Revolutionizing Metallic Biomaterials(ERC-RMB) Department of Mechanical EngineeringNorth Carolina A&T State University

A uniform, compact, and well adherent conversion coating of magnesium hydroxide has been formed on bioresorbable magnesium disks by means of a hydrothermal technique. Electrochemical results indicate that the coating brings about a significant reduction in magnesium corrosion in phosphate buffered saline （PBS） solution. It is also observed that corrosion resistance of the coating increases with an increase in treatment time, which in turn, increases the coating thickness. The protective behavior of magnesium hydroxide coating is attributed to its chemical inertness in PBS solution. The coatings are found to be free from pores that reduce the direct contact between corroding media and underlying magnesium.

关键词： Magnesium Polarization Electrochemical impedance spectroscopy (EIS) Scanning electron microscopy (SEM) Conversioncoating Corrosion

New Exact Traveling Wave Solutions of the Unstable Nonlinear Schrdinger Equations

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Communications in Theoretical Physics 2017年第12期67卷 761-767页

作者： K.Hosseini d.kumar M.Kaplan E.Yazdani Bejarbaneh department of Mathematics Rasht Branch Islamic Azad University Graduate School of Systems and Information Engineering University of Tsukuba department of Mathematics Bangabandhu Sheikh Mujibur Rahman Science and Technology University department of Mathematics Art-Science Faculty Kastamonu University Young Researchers and Elite Club Qazvin Branch Islamic Azad University

The present paper studies the unstable nonlinear Schr¨odinger equations, describing the time evolution of disturbances in marginally stable or unstable media. More precisely, the unstable nonlinear Schr¨odinger equation and its modified form are analytically solved using two efficient distinct techniques, known as the modified Kudraysov method and the sine-Gordon expansion approach. As a result, a wide range of new exact traveling wave solutions for the unstable nonlinear Schr¨odinger equation and its modified form are formally obtained.

关键词： unstable nonlinear SchrSdinger equation modified unstable nonlinear Schrodinger equation mod-ified Kudryashov method sine-Gordon expansion approach new exact traveling wave solutions

Enhanced corrosion resistance of phytic acid coated magnesium by stearic acid treatment

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Transactions of Nonferrous Metals Society of China 2013年第5期23卷 1237-1244页

作者： R.K.GUPTA K.MENSAH-dARKWA J.SANKAR d.kumar Engineering Research Center for Revolutionizing Metallic Biomaterials(ERC-RMB) North Carolina A&T State University

A green chemical conversion coating for magnesium was obtained with a phytic acid solution. The microstructure and corrosion properties of phytic acid conversion coated magnesium were further improved by soaking in stearic acid solution. The phytic acid conversion coated magnesium after soaking in the stearic acid showed no micro-cracks and the surface became very smooth. The corrosion behavior of the uncoated and coated magnesium samples was studied by electrochemical methods. The corrosion resistance of the stearic acid treated sample was much higher than that of phytic acid conversion coated magnesium or uncoated magnesium. The electrochemical results indicated that the stearic acid treated coating provided effective corrosion protection to the magnesium sample.

关键词： magnesium phytic acid stearic acid corrosion impedance spectroscopy

The L4n laser beamline of the P3-installation:Towards high-repetition rate high-energy density physics at ELI-Beamlines

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Matter and Radiation at Extremes 2021年第1期6卷 45-53页

作者： N.Jourdain U.Chaulagain M.Havlik d.Kramer d.kumar V.T.Tikhonchuk G.Korn S.Weber ELI-Beamlines Institute of PhysicsCzech Academy of Sciences18221 PragueCzech Republic Centre Lasers Intenses et Applications University of Bordeaux-CNRS-CEA33405 TalenceFrance School of Science Xi’an Jiaotong UniversityXi’an 710049China

The P3 installation of ELI-Beamlines is conceived as an experimental platform for multiple high-repetition-rate laser beams spanning time scales from femtosecond via picosecond to *** upcoming L4n laser beamline will provide shaped nanosecond pulses of up to 1.9 kJ at a maximum repetition rate of 1 shot/*** beamline will provide unique possibilities for high-pressure,high-energy-density physics,warm dense matter,and laser–plasma interaction *** to the high repetition rate,it will become possible to obtain considerable improvements in data statistics,in particular,for equation-of-state data *** nanosecond beam will be coupled with short sub-picosecond pulses,providing high-resolution diagnostic tools by either irradiating a backlighter target or driving a betatron setup to generate energetic electrons and hard X-rays.

关键词： laser repetition beam