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Transport mechanism in chemically reactive hybrid nanofluid flow containing gyrotactic micro-organisms over a curved oscillatory surface

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Applied mathematics and mechanics(English Edition) 2025年第1期46卷 177-192页

作者： m.NAVEED m.ImRAN T.ASGHAR z.ABBAS Department of mathematics Division of Science and TechnologyUniversity of Education Department of mathematics The Islamia University of Bahawalpur

This paper examines the transport analysis, including both heat transfer and mass transfer, in hybrid nanofluid flow containing gyrotactic microorganisms towards a curved oscillatory surface. The influence of magnetic fields is also inspected in terms of their physical characteristics. To depict the phenomena of transport, modified versions of both Fick's and Fourier's laws are used. Additionally, the characteristics of both heterogeneous and homogeneous chemical reactions are also incorporated. Utilizing a curvilinear coordinate system, the flow problem is formulated as partial differential equations(PDEs)for momentum, concentration, microorganism field, and energy. An analytical solution to the obtained flow equations is achieved utilizing the homotopy analysis method(HAm).The effects of significant flow parameters on the pressure and microorganism fields, velocity, oscillation velocity, concentration, and temperature distributions are shown via graphs. Furthermore, the variations in skin friction, mass transfer rate, heat transfer rate, and local motile number due to different involved parameters are presented in tables and are analyzed in detail. Graphical results indicate that the curves of velocity and temperature fields are enhanced as the values of the solid volume fraction variables *** is also verified that the concentration rate field decreases as the values of the homogeneous reaction strength parameter and the radius of curvature parameter increase, and it increases with the Schmidt number and the heterogeneous reaction strength *** outcomes show a favorable response of the motile number to advanced values of the Peclet number, the Schmidt number, the microorganism difference parameter, and the bio-convective Lewis number.

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Impacts of the annual cycle of background SST in the tropical Pacific on the phase and amplitude of ENSO

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Atmospheric and Oceanic Science Letters 2025年第1期18卷 12-17页

作者： song Jiang Congwen zhu Ning Jiang State Key Laboratory of Severe Weather(LASW) Chinese Academy of Meteorological SciencesBeijingChina College of Earth and Planetary Sciences University of Chinese Academy of SciencesBeijingChina

The dominant annual cycle of sea surface temperature(SST)in the tropical Pacific exhibits an antisymmetric mode,which explains 83.4%total variance,and serves as a background of El Niño-Southern Oscillation(ENSO).However,there is no consensus yet on its anomalous impacts on the phase and amplitude of *** on data during 1982-2022,results show that anomalies of the antisymmetric mode can affect the evolution of ENSO on the interannual scale via Bjerknes feedback,in which the positive(negative)phase of the antisymmetric mode can strengthen El Niño(La Niña)in boreal winter via an earlier(delayed)seasonal cycle transition and larger(smaller)annual *** magnitude of the SST anomalies in the equatorial eastern Pacific can reach more than±0.3◦C,regulated by the changes in the antisymmetric mode based on random sensitivity *** reveal the spatial pattern of the annual cycle associated with the seasonal phase-locking of ENSO evolution and provide new insight into the impact of the annual cycle of background SST on ENSO,which possibly carries important implications for forecasting ENSO.

关键词： Annual cycle SST anomaly Antisymmetric mode ENSO

Infrared, Diffuse Reflectance and Dielectric Studies ofAntimony Trisulphide

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Journal of materials Science & Technology 1998年第4期14卷 344-348页

作者： Hanafi, z.m. Ismail, F.m. Khalil, m.Sh. Inorganic Chemistry Dept. National Research Centre Dokki Cairo Egypt

Infrared absorption spectra of orange, black and transferred Sb//2S//3 samples have been studied in the spectral range 200-4000 cm** minus **1. The pronounced difference between the different samples is the appearance of excess sulphur present in the orange and transferred samples except those of transferred at 543 K and the black Sb//2S//3. The change of sharpness of some IR peaks reveals the amorphous/crystalline change. The effect of the degree of crystallinity and stoichiometry on the energy gap values was investigated by using optical method. The obtained dielectric parameters epsilon prime and epsilon double prime of the different samples are thoroughly affected by the degree of crystallinity and smoothly affected by either the frequency or the temperature or both, except at lower frequencies. (Edited author abstract) 26 Refs.

关键词： Antimony compounds

Residual Strains in a Nanometer Thick Cr Film measured on micromachined Beams

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Journal of materials Science & Technology 2009年第1期25卷 77-80页

作者： z.m. zhou Yong zhou Ying Cao Haiping mao Key Laboratory for Thin Film and microfabrication Technology of ministry of Education Research Institute of Micro/Nano Science and Technology Shanghai Jiao Tong University Shanghai 200030 China

A Cr film with a 75 nm thickness sputtered on a Si substrate was used to fabricate microbridge and microcantilever samples with the mEmS （microelectromechanical system） technique. The profile of the buckled beams was measured by using the interference technique with white light and fitted with a theoretical result. The uniform residual strain in the bridge samples was deduced from the variation of buckling amplitude with the beam length. On the other hand, the gradient residual strain was determined from the deflection profile of the cantilever. The residual uniform and gradient strain in the Cr film are about 4.96×10^-3 and 4.2967×10^-5, respectively.

关键词： Residual Strain microelectromechanical system (mEmS) microbridge microcantilever

mICROSTRUCTURE OF mg-6.4zn-1.1Y ALLOY FABRICATED BY RAPID SOLIDIFICATION AND RECIPROCATING EXTRUSION

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Acta metallurgica Sinica(English Letters) 2008年第1期21卷 30-36页

作者： z.m. zhang C.J. Xu X.F. Guo School of materials Science ＆ Engineering Xi＇an University of Technology Xi＇an 710048 China

In order to explore the methods to prepare high-strength quasicrystal-reinforced magnesium alloys, the flakes of rapidly solidified mg-6.4zn-1.1 Y magnesium alloy with a thickness of 50-60μm were obtained by a melt spinning single-roller device, and the flakes were then processed into rods by reciprocating extrusion and direct extrusion. The microstructure of the alloy was analyzed by optical microscope and SEm, and the constituent phases were identified by XRD. Phase transformation and its onset temperature were determined by differential thermal analyzer （DTA）. The analysis result shows that rapid solidification for *** alloy can inhibit the eutectic reactions, broaden the solid solubility of zn in α-mg solute solution, and impede the formation of mg3 Y2zn3 and mgzn2 compounds, and thus help the icosahedral mg3 Yzn6 quasicrystal formed directly from the melt. The microstructure of the flakes consists of the α-mg solid solution and icosahedral mg3 Yzn6 quasicrystal. Dense rods can be made from the flakes by two-pass reciprocating extrusion and direct extrusion. The interfaces between flakes in the rods can be welded and jointed perfectly. During the reciprocating extrusion and direct extrusion process, more mg3 Yzn6 compounds are precipitated and distributed uniformly, whereas the rods possess fine microstructures inherited from rapidly solidified flakes. The rods contain only two phases： α- magnesium solid solution as matrix and fine icosahedral mg3 Yzn6 quasicrystal which disperses uniformly in the matrix.

关键词： magnesium alloy Rapid solidification Reciprocating extrusion Quasicrystal

mICROSTRUCTURES AND PROPERTIES OF RECIPROCATINGLY EXTRUDED mg-6.4zn-1.1Y ALLOYS

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Acta metallurgica Sinica(English Letters) 2008年第1期21卷 37-42页

作者： z.m. zhang C.J. Xu X.F. Guo School of materials Science ＆ Engineering Xi＇an University of Technology Xi＇an 710048 China

An icosahedral mg3 Yzn6 quasicrystalline phase can be produced in mg-zn- Y system alloys when a proper amount of zn and Y is contained, and it is feasible to prepare the quasicrystal phase-reinforced low-density magnesium alloy. In this article, phase constituents and the effect of reciprocating extrusion on microstructures and properties of the as-cast mg-6.4zn-1.1 Y alloy are analyzed. The microstructure of the as-cast mg-6.4zn-1.1 Y alloy consists of the α-mg solid solution, icosahedral mg3Yzn6 quasicrystal, and mg3 Y2zn3 and mgzn2 compounds. After the alloy was reciprocatingly extruded for four passes, grains were refined, mg3 Y2 zn3 and mgzn2 phases dissolved into the matrix, whereas, mg3 Yzn6 precipitated and distributed uniformly. The alloy possesses the best performance at this state; the tensile strength, yield strength, and elongation are 323.4 mPa, 258.2 mPa, and 19.7%, respectively. In comparison with that of the as-cast alloy, the tensile strength, yield strength, and elongation of the reciprocatingly extruded alloy increase by 258.3%, 397.5%, and 18 times, respectively. It is concluded that reciprocating extrusion can substantially improve the properties of the as-cast mg-6.4zn-1.1 Y alloy, particularly for elongation. The high performance of the mg-6.4zn-1.1 Y alloy after reciprocating extrusion can be attributed to dispersion strengthening and grain-refined microstructures.

关键词： Reciprocating extrusion mg-zn- Y alloy Icosahedral quasicrystal

RECIPROCATING EXTRUSION OF IN SITU mg_2Si REINFORCED mg-Al BASED COmPOSITE

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Acta metallurgica Sinica(English Letters) 2008年第3期21卷 169-177页

作者： z.m. zhang C.J. Xu X.F. Guo S.z. Jia School of materials Science ＆ Engineering Xi＇an University of Technology Xi＇an 710048 China

m92Si reinforced mg-Al based composite with high amount o/silicon was prepared by permanent mould casting, and then extruded by reciprocating extrusion （RE） after the composite was processed by homogenization heat treatment. The effect of RE processing on the morphology and size of m92Si and the mechanical properties of the com- posite were investigated, to develop new ways to refine the m928i phase and improve its shape. The result showed that RE was very useful in refining the m92Si phase. The more the RE processing passes, the better the refining effect would be. moreover, the uniform distribution of m928i phases would be more in the composite. After the composite was processed by RE for 12 passes, most m92Si phases were equiaxed, with granular diameter below 20 μm, and distributed uniformly in the matrix of the composite. The mechanical properties of the composite could be increased prominently by RE processing, and were much higher than that in the as-cast state. As the temperature rises, the tensile strength is reduced. For the composite RE processed for 12 passes, the tensile strength, yield strength, and elongation are 325.9 mPa, 211.4 mPa, and 3.3% at room temperature, whereas, 288.2 mPa, ,207.7 mPa, and 7.8%, respectively, at 150℃. In comparison with the properties at room temperature, the tensile strength and yield strength are high and only decrease by 11.6% and 1.8% at 150℃. The m928i reinforced mg-Al based composite possesses good heat resistance at 150℃. The excellent resistance to effect of heat is attributed to the high melting tempera- ture and good thermal stability of fine mg2Si phases, which are distributed uniformly in the composite, and effectively hinder the grain boundary gliding and dislocation movement.

关键词： Reciprocating extrusion magnesium alloy In situ composite Elevated temperature property

EFFECT OF ANNEALING ON DAmPING CAPACITIES OF AS-CAST zA27 ALLOY

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Acta metallurgica Sinica(English Letters) 2006年第5期19卷 379-384页

作者： z.m. zhang J. C. Wang H.z. Liu X.F. Guo School of materials Science ＆ Engineering Xi＇an University of TechnologyXi＇an 710048 China State Key Laboratory of Solidification Processing Northwestern PolytechnicalUniversity Xi＇an 710072 China

zA27 alloy was prepared by casting with permanent mold and then annealed at 250℃ for 1-4h. The damping capaciG of the alloy was measured using a testing apparatus based on the cantilever beam technique. It was found that the as-cast zA27 alloy possesses high damping capacity with the value of 1.3 × 10^4 at 320Hz. After annealed at 250℃ for lh, the damping capacity decreases to 1.1 × 10^-3 and then remains constant even when the annealing time is increased to 4h. The microstructure of the as-cast zA27 alloy consists of large dendrites of Al-rich PrimaG （x-phases, eutectoid （α ＋ η） and nonequilibrium eutectic phases （α ＋ η ＋ ε）. After annealing at 250℃ for lh, the e phase disappears due to dissolution into the matrix, and the spacing between the flakes of eutectoid increases. The further increase in the annealing time has little effect on the spacing. The damping mechanism of the alloy was discussed considering the thermoelastic damping and defect damping. The value of thermoelastic damping accounts only for 7%-8% in the overall damping in cantilever beam damping measurements and the damping capacity of the zA27 alloy came mainly from defect damping.

关键词： damping capacity zA27 alloy annealing

DAmPING BEHAVIOR OF ULTRAFINE-GRAINED PURE ALUmINUm L2 AND THE DAmPING mECHANISm

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Acta metallurgica Sinica(English Letters) 2006年第3期19卷 223-227页

作者： z.m. zhang C.J. Xu J.C. Wang H.z. Liu School of materials Science ＆ Engineering Xi＇an University of Technology Xi＇an 710048 Ghina State Key Laboratory of Solidification Processing Northwestern Polytechnical University Xi＇an 710072 Ghina

Ultrafine-grained pure aluminum L2 with a mean grain size of 1.01μm was produced by equal channel angular pressing （ECAP） and annealing at 150℃ for 2h. Damping behavior of the alloy was measured using a dynamic mechanical thermal analyzer. The alloy had an excellent damping capacity Q^-1 with the ambient value being 9.8×10^-3 at 1.0Hz when the strain amplitude was 2.0×10^-5. The damping behavior of the alloy showed a non-linear damping variation tendency, that is, with an increase in temperature and a decrease of frequency, the damping capacity of the alloy increased. The damping capacity increased with the strain amplitude when the strain amplitude was less than 4.6×10^-5. When the strain amplitude was higher than 4.6×10^-5, the damping capacity became a constant and independent of strain amplitude. The high damping capacity was attributed to dislocation unpinning and a drag of dislocation on pinning points.

关键词： ECAP ultrafine grain damping capacity aluminum alloy