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Effect of hydrogen fluoride and magnesium oxide on AZ31 Mg alloy/carbon fiber-reinforced plastic composite by thermal laser joining technique

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Journal of Magnesium and Alloys 2024年第7期12卷 2874-2889页

作者： Andrews Nsiah Ashong barton Mensah Arkhurst Youn Seoung Lee Mok-Young Lee Jeoung Han Kim School of Materials Science&Engineering University of New South Wales SydneyNSW2052Australia department of Information and communication Engineering Hanbat National UniversityYuseong-guDaejeonSouth Korea Welding&joining research group steel solution research laboratoryPOSCOIncheonRepublic of Korea department of Materials Science&Engineering Hanbat National UniversityYuseong-guDaejeonSouth Korea

Although hydrofluoric acid(HF)surface treatment is known to enhance the joining of metals with polymers,there is limited information on its effect on the joining of AZ31 alloy and carbon-fiber-reinforced plastics(cFRPs)through laser-assisted metal and plastic direct joining(LAMP).This study uses the LAMP technique to produce AZ31-cFRP *** joining process involves as-received AZ31,HFpretreated AZ31,and thermally oxidized HF-pretreated AZ31 alloy ***,the bonding strength of joints prepared with thermally oxidized AZ31 alloy sheets is examined to ascertain the combined effect of HF treatment and thermal oxidation on bonding *** microstructures,surface chemical interactions,and mechanical performances of joints are investigated under tensile shear *** factors,such as bubble formation,cFRP resin decomposition,and mechanical interlocking considerably affect joint ***,surface chemical interactions between the active species on metal parts and the polar amide along with carbonyl groups of polymer play a significant role in improving joint *** prepared with surface-pretreated AZ31 alloy sheets show significant improvements in bonding strength.

关键词： Thermal laser joining Thermal oxidation Hydrofluoric acid pretreatment Mechanical interlocking covalent bonds chemical interactions

co-evolution of nuclear rings,bars and the central intensity ratio of their host galaxies

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Research in Astronomy and Astrophysics 2020年第2期20卷 15-20页

作者： S.Aswathy c.d.Ravikumar department of Physics University of Calicut

Using a sample of 13 early-type spiral galaxies hosting nuclear rings,we report remarkable correlations between the properties of the nuclear rings and the central intensity ratio(cIR) of their host *** cIR,a function of intensity of light within the central 1.5 and 3 arcsec region,is found to be a vital parameter in galaxy evolution,as it shares strong correlations with many structural and dynamical properties of early-type galaxies,including mass of the central supermassive black hole(SMBH).We use archival HST images for aperture photometry at the centre of the galaxy image to compute the *** observe that the relative sizes of nuclear rings and ring cluster surface densities strongly correlate with the *** correlations suggest reduced star formation in the centres of galaxies hosting small and dense nuclear *** scenario appears to be a consequence of strong bars as advocated by the significant connection observed between the cIR and bar *** addition,we observe that the cIR is closely related with the integrated properties of the stellar population in the nuclear rings,associating the rings hosting older and less massive star clusters with low values of ***,the cIR can serve as a crucial parameter in unfolding the coupled evolution of bars and rings as it is intimately connected with both their properties.

关键词： galaxies:evolution galaxies:formation galaxies:photometry galaxies:spiral galaxies:starburst

Experimental study on the microstructural and anti-corrosion behaviour of co-deposition Ni-co-SiO_2 composite coating on mild steel

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defence Technology（防务技术） 2018年第1期14卷 64-69页

作者： c.U.Atuanya d.I.Ekweghiariri c.M.Obele department of Metallurgical and Materials Engineering Nnamdi Azikiwe UniversityAwkaAnambra StateNigeria department of Polymer and Textile Engineering Nnamdi Azikiwe UniversityAwkaAnambra StateNigeria

Mild steel is commonly used in the construction of Pipeline. The major problem of this Pipeline is corrosion. Effort is make my researchers to combat this problem. In this work co-deposition of Ni-coSiO_2 composite coating on mild steel was reported with the view to reduce this problem. The SiO_2 was varies from 5 to 25 wt% in the deposition. The microstructure, hardness values and potentiodynamic polarization in simulated sea water were determined. The results show that XRd pattern of the Ni co deposited mild steel revealed the presence hard phases of NiO, co_5Ni, co_2Ni_3, Ni co5 while that of Ni-coSiO_2 deposited mild steel revealed the presence harder phases of NiOSiO_2, coNi_7Si_2, co_5Ni_2Si_3. The Nico-25 SiO_2 deposited sample has smaller particle size than Ni-10 co coating. coating thickness of 110.7 mm was obtained for Ni-10 co coating, while coating thickness of 135.7, 157.7, 165.0 mm were obtained at Ni-10 co-x SiO_2(x=10, 15, 25 wt%). 99.90% corrosion resistance was achieved at Ni-co-25 SiO_2. This improvement in corrosion resistance after composites coating could be attributed to the hard and fine structure obtained after coating.

关键词： co-deposition corrosion Microstructure and coating

NUMERIcAL SOLUTIONS OF INcOMPRESSIBLE EULER ANd NAVIER-STOKES EQUATIONS BY EFFIcIENT dIScRETE SINGULAR cONVOLUTION METHOd

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Acta Mechanica Sinica 2000年第3期16卷 223-239页

作者： d.c.Wan G.W.Wei Shanghai Univ Shanghai Inst Appl Math&MechShanghai 200072Peoples R China Natl Univ Singapore Dept Computat SciSingapore 119260Singapore

An efficient discrete singular convolution (dSc) method is introduced to the numerical solutions of incompressible Euler and Navier-Stokes equations with periodic boundary conditions. Two numerical tests of two-dimensional Navier-Stokes equations with periodic boundary conditions and Euler equations for doubly periodic shear layer flows are carried out by using the dSc method for spatial derivatives and fourth-order Runge-Kutta method for time advancement, respectively. The computational results show that the dSc method is efficient and robust for solving tho problems of incompressible flows, and has the potential of being extended to numerically solve much broader problems in fluid dynamics.

关键词： incompressible flows periodic boundary dSc method fourth-order Runge-Kutta method

A dIREcT SEARcH FRAME-BASEd cONJUGATE GRAdIENTS METHOd

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Journal of computational Mathematics 2004年第4期22卷 489-500页

作者： I.d.coope c.J.Price departmentofMathematicsandStatistics UniversityofCanterburyPrivateBag4800ChristchurchNewZealand

A derivative-free frame-based conjugate gradients algorithm is presented. convergence is shown for c^1 functions, and this is verified in numerical trials. The algorithm is tested on a variety of low dimensional problems, some of which are ill-conditioned, and is also tested on problems of high dimension. Numerical results show that the algorithm is effective on both classes of problems. The results are compared with those from a discrete quasiNewton method, showing that the conjugate gradients algorithm is competitive. The algorithm exhibits the conjugate gradients speed-up on problems for which the Hessian at the solution has repeated or clustered eigenvalues. The algorithm is easily parallelizable.

关键词： conjugate gradients derivative-free Frame-based methods Numerical results

Effect of the firing position on aiming error and probability of hit

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defence Technology（防务技术） 2019年第5期15卷 713-720页

作者： d.corriveau c.A.Rabbath A.Goudreau defence R&d canada 2459 De La Bravoure Rd.QuebecQC G3J 1X5Canada Munitions Experimental Test center 2459 De La Bravoure Rd.QuebecQC G3J 1X5Canada

Sources of dispersions that contribute to delivery error and reduce the soldier performance in terms of hit probability are *** order to improve the warfighter performance,the source of the errors contributing to the inaccuracy and dispersion of the weapon systems must be *** include ammunition dispersion error,gun dispersion,aerodynamic jump and the aiming *** aiming error or gun pointing error is defined as the angle between the gun muzzle at the instant the trigger is pulled and the line of fire that corresponds to the intendent aim *** is a round-to-round *** weapons systems that include the rifle,the ammunition,a sight and a gunner,the aiming error was shown to be the single most important source of dispersion for the regular *** other words,for the general purpose rifle weapon system,the weak link is often the *** order to verify and quantify this assertion,an experimental investigation was carried out to determine the aiming error associated with general purpose rifle fired by *** aiming error was evaluated for various firing positions and scenarios using infantryman for ranges varying between 100 m and 500 *** results show that the aiming error is the main contributor to dispersion for the general purpose rifle fired by a non-specialized *** aiming error induced dispersion for unstressed and rested gunners is shown to be at best equivalent to that of the weapon fired from a bench rest by a *** copyright(?) 2019 Production and hosting by Elsevier *** behalf of china Ordnance Society.

关键词： Aiming error Rifle Position Range dispersion

Modified Joint distribution of Wave Heights and Periods

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china Ocean Engineering 2016年第3期30卷 359-374页

作者： H.d.Zhang c.Guedes Soares centre for Marine Technology and Ocean Engineering (cENTEc) Instituto Superior Técnico Universidade de Lisboa

The modified versions of the linear theoretical model of Longuet-Higgins （1983） are derived in this work and also compared with the laboratory experiments carried out in MAR1NTEK. The main feature of modifications is to replace the mean frequency in the formulation with the peak frequency of the wave spectrum. These two alternative forms of joint distributions are checked in three typical random sea states characterized by the initial wave steepness. In order to further explore the properties ＆these models, the associated marginal distributions of wave heights and wave periods are also researched with the observed statistics and some encouraging results are obtained.

关键词： Longuet-Higgins joint distribution mixed sea state nonlinear wave series wave height wave period

Evaluation of effects of 1,3-dinitrobenzene on sperm motility of hamster using computer assisted semen analysis (cASA)

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Asian Journal of Andrology 2001年第2期3卷 109-114页

作者： L.d.c.Peiris H.d.M.Moore dept. of Zoology University of Colombo Colombo 03 Sri LankaDept. of Molecular Biology and Biotechnology University of Sheffield Sheffield S 10 2TN UK

Aim: To evaluate the effects of 1,3-dinitrobenznene (mdNB) on sperm motility of hamster and to correlate the re-sults with the fertility. Methods: Adult male hamsters were gavaged with one of the 3 dose regimes of mdNB(1.5 mg daily for 4 weeks ,1.5 mg one day a week for 4 weeks and 1.0 mg 3 days a week for 4 weeks). computerassisted semen analysis (cASA) was used to analyse the sperm motility parameters, curvilinear velocity (VcL) andstraight line velocity (VSL) of sperm in distal corpus epididymides and distal cauda epididymides. In vitro fertilisationwas carried out only for 1.5 mg mdNB daily group to determine the sperm fertilising capacity. Results: There wasa significant reduction in sperm velocity parameters at weeks 3 and 4 after treatment, which was correlated with a de-cline in sperm fertility. conclusion; Sperm velocity parameters may be used to determine the effect of a toxic insulton the sperm function.

关键词： mdNB sperm motility cASA sperm fertility

discriminative predation： Simultaneous and sequential encounter experiments

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current Zoology 2012年第4期58卷 649-657页

作者： c. d. BEATTY d. W. FRANKS department of Biology Santa Clara University Santa Clara California USA cbeatty@ scu.edu York centre for complex Systems Analysis and Department of Biology and Department of Computer Science University ofYork York YO10 5YW UK

There are many situations in which the ability of animals to distinguish between two similar looking objects can have significant selective consequences. For example, the objects that require discrimination may be edible versus defended prey, predators versus non-predators, or mates of varying quality. Working from the premise that there are situations in which discrimi- nation may be more or less successful, we hypothesized that individuals find it more difficult to distinguish between stimuli when they encounter them sequentially rather than simultaneously. Our study has wide biological and psychological implications from the perspective of signal perception, signal evolution, and discrimination, and could apply to any system where individuals are making relative judgments or choices between two or more stimuli or signals. While this is a general principle that might seem intuitive, it has not been experimentally tested in this context, and is often not considered in the design of models or experiments, or in the interpretation of a wide range of studies. Our study is different from previous studies in psychology in that a） the level of similarity of stimuli are gradually varied to obtain selection gradients, and b） we discuss the implications of our study for specific areas in ecology, such as the level of perfection of mimicry in predator-prey systems. Our experiments provide evidence that it is indeed more difficult to distinguish between stimuli - and to learn to distinguish between stimuli - when they are encountered sequentially rather than simultaneously, even if the intervening time interval is short .

关键词： Receiver psychology Stimulus selection discrimination Imperfect mimicry Predation