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Semi-oxalate synthesis of (1-x)BaTiO3-xM0.5Bi0.5TiO3 (M =Li, Na, K)PTCR materials

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Journal of Advanced Ceramics 2016年第2期5卷 117-125页

作者： T.A.PLUTENKO O.i.V'YUNOV A.G.BELOUS O.z.YANCHEVSKii Vernadskii institute of General and inorganic Chemistry of the Ukrainian NAS Prospect Palladina 32/34 Kyiv 142 03680 Ukraine

(1?x)BaTiO3-xM0.5Bi0.5TiO3 (M = Li, Na, K) solid solutions were prepared using BaTiO3 pre-synthesized by oxalate method. The stability limits of (1?x)BaTiO3-xLi0.5Bi0.5TiO3 solid solutions have been established. it was shown that increase in M0.5Bi0.5TiO3 concentration results in reduction of ceramic grain size in the (1?x)BaTiO3?xM0.5Bi0.5TiO3 (M = Li, Na, K) system. it was found that the positive temperature coefficient of resistance (PTCR) effect in lead-free materials is due to the presence of a semiconductor core, which is formed by sintering under reducing atmosphere, and dielectric grain boundaries, formed on additional oxidation in air. The use of barium titanate, pre-synthesized by oxalate method, in the synthesis of solid solutions reduced the sintering temperature of ceramics compared with solid state reaction technique. By comparing the electrical properties of the synthesized lead-containing and lead-free materials, it has been shown that lead-free materials exhibit better electrical properties for practical use compared with lead-containing materials.

关键词： lead-free ceramic BaTiO3 semi-oxalate method positive temperature coefficient of resistance (PTCR) effect

Dynamics of bioconvection flow of micropolar nanoparticles with Cattaneo-Christov expressions

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Applied Mathematics and Mechanics(English Edition) 2020年第9期41卷 1333-1344页

作者： S.A.SHEHzAD T.MUSHTAQ z.ABBAS A.RAUF S.U.KHAN i.TLiLi Department of Mathematics COMSATS University IslamabadSahiwal 57000Pakistan Department of Mathematics COMSATS University IslamabadVehari 61100Pakistan Department of Mathematics The Islamia University of BahawalpurBahawalpur 63100Pakistan institute of Research and Development Duy Tan UniversityDa Nang 550000Vietnam Faculty of Civil Engineering Duy Tan UniversityDa Nang 550000Vietnam

A numerical analysis is performed to analyze the bioconvective double diffusive micropolar non-Newtonian nanofluid flow caused by stationary porous *** consequences of the current flow problem are further extended by incorporating the Brownian and thermophoresis *** energy and mass species equations are developed by utilizing the Cattaneo and Christov model of heat-mass *** flow equations are converted into an ordinary differential model by employing the appropriate *** numerical solution is reported by using the MATLAB builtin bvp4c *** consequences of engineering parameters on the flow velocity,the concentration,the microorganisms,and the temperature profiles are evaluated *** numerical data for fascinating physical quantities,namely,the motile density number,the local Sherwood number,and the local Nusselt number,are calculated and executed against various parametric *** microrotation magnitude reduces for increasing magnetic *** intensity of the applied magnetic field may be utilized to reduce the angular rotation which occurs in the lubrication processes,especially in the suspension of *** the account of industrial applications,the constituted output can be useful to enhance the energy transport efficacy and microbial fuel cells.

关键词： bioconvection flow micropolar fluid nanoparticle Cattaneo-Christov theory porous disk

Exergy analysis of R1234ze（z） as high temperature heat pump working fluid with multi-stage compression

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Frontiers in Energy 2017年第4期11卷 493-502页

作者： Bin HU Di WU L.W. WANG R.z. WANG institute of Refrigeration and Cryogenics Shanghai Jiao Tong University Shanghai 200240 China

in this paper, the simulation approach and exergy analysis of multi-stage compression high tempera- ture heat pump （HTHP） systems with R1234ze（z） working fluid are conducted. Both the single-stage and multi-stage compression cycles are analyzed to compare the system performance with 120℃ pressurized hot water supply based upon waste heat recovery. The exergy destruction ratios of each component for different stage compression systems are compared. The results show that the exergy loss ratios of the compressor are bigger than that of the evaporator and the condenser for the single-stage compres- sion system. The multi-stage compression system has better energy and exergy etticiencies with the increase of compression stage number. Compared with the single- stage compression system, the coefficient of performance （COP） improvements of the two-stage and three-stage compression system are 9.1% and 14.6%, respectively. When the waste heat source temperature is 60℃, the exergy efficiencies increase about 6.9% and 11.8% for the two-stage and three-stage compression system respec- tively.

关键词： multi-stage compression high temperatureheat pump heat recovery exergy destruction,R1234ze(z) working fluid

RAFTiNG PREDiCTiON CRiTERiON FOR NiCKEL-BASE SiNGLE CRYSTALS UNDER MULTiAXiAL STRESSES AND CRYSTALLOGRAPHiC ORiENTATiON DEPENDENCE OF CREEP BEHAViOR

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Acta Metallurgica Sinica(English Letters) 1999年第2期12卷 149-154页

作者： Yue, z.F. Lu, z.z. Northwestern Polytechnical Univ Xi'an China

Based on the relief of interfacial energy density by dislocation generation at the gamma - gamma ' interfaces, a rafting prediction criterion has been developed for nickel-base single crystals under multiaxial stresses. The diagrams of rafting have been presented, and confirmed by experimental results. The rafting process have been analyzed quantitatively by the relief of interfacial energy. The criterion has been applied to study the creep behavior. The example of creep life analysis shows that the criterion can be correlated greatly to the crystallographic orientation dependence of creep behavior. (Author abstract) 11 Refs.

关键词： Creep Crystallography Dislocations (crystals) interfaces (materials) interfacial energy Single crystals Superalloys

Microstructural evolution,dislocation density and tensile properties of Al–6.5Si–2.1Cu–0.35Mg alloy produced by different casting processes

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Journal of Materials Science & Technology 2021年第36期95卷 145-157页

作者： S.Samat M.z.Omar A.H.Baghdadi i.F.Mohamed A.Rajabi A.M.Aziz Department of Mechanical and Manufacturing Engineering Faculty of Engineering and Built EnvironmentUniversiti Kebangsaan MalaysiaBangiUKM 43600Malaysia

Al–Si–Cu–Mg foundry alloys are used in casting process ***,their strength properties remain low due to their microstructural characteristics and *** this work,the microstructural characteristics,dislocation densities,and mechanical properties of Al–Si–Cu–Mg cast alloys prepared through different casting methods were studied *** casting processes,namely,gravity casting(GC),rheocasting(RC),thixoforming(Thixo),and Thixo with heat treatment,were *** GC and RC samples had mainly dendriticα-Al phase microstructures and exhibited coarse Si particles and intermetallic compounds in their interdendritic *** contrast,the Thixo and heat-treated Thixo(HT-Thixo)samples exhibited microstructural refinement with uniformly distributedα-Al globules,fine fibrous Si particles,and fragmented intermetallic compounds amongα-Al *** accumulation of dislocation densities increased in the Thixo sample as the strain was increased due to plastic ***,the ultimate tensile strength and yield strength of the HT-Thixo sample increased by 87%and 63%,respectively,relative to those of the GC *** cleavage fracture displayed by the GC and RC samples led to brittle ***,the Thixo and HT-Thixo samples presented dimple-based ductile fracture.

关键词： Al–Si–Cu–Mg alloy Thixoforming Microstructure Mechanical property Dislocation density

Occurrence of Clinostomum complanatum in Aphanius dispar(Actinoptrygii:Cyprinodontidae) collected from Mehran River,Hormuzgan Province,South of iran

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Asian Pacific Journal of Tropical Biomedicine 2011年第3期1卷 189-192页

作者： Gholami z Mobedi i Esmaeili HR Kia EB Department of Geo-and Environmental Sciences Palaeontology and Geobiology Ludwig-Maximilians-University Munich Department of Medical Parasitology and Mycology School of Public HealthUniversity of Medical Sciences Department of Biology College of ScienceShiraz University

Objective:To investigate the possibility of Aphanius dispar(***) acting as intermediate host for Clinostomum complanalum(***),from Mehran River,Hormuzgan Province of ***:During a biological study of *** in Mehran River,Hormuzgan Province,South of iran,a total of 97 fish specimens were collected in 24 January ***: 4 specimens(4.12%) including 1 male and 3 female were found infected with *** *** metacercaria were coiled in the epiderm on the body surface of infected *** infection is known as yellow spot *** parasite abundance,intensity and prevalence were 0.03%,1.25%and 4.12%,*** infection was higher in females than ***:To the best of our knowledge,this is the first report on occurrence of C. complanatum metacercaria in *** in iran.

关键词： Aphanius dispar Clinostomum complanatum Metacercaria Hormuzgan province iran

Effect of Surface Polishing Treatment on the Fatigue Performance of Shot-Peened Ti–6Al–4V Alloy

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Acta Metallurgica Sinica(English Letters) 2017年第7期30卷 630-640页

作者： z.G.Liu T.i.Wong W.Huang N.Sridhar S.J.Wang institute of High Performance Computing A＊STAR 1 Fusionopolis Way Singapore 138632 Singapore institute of Materials Research and Engineering A＊STAR 2 Fusionopolis Way Singapore 138634 Singapore

in this study, shot peening is applied to the titanium alloy Ti–6Al–4V, and the surface treatment effect on fatigue life of shot-peened specimens under high cycle loading is investigated. The induced residual stress is measured by using the orbital hole-drilling method. Surface profilometer and optical microscopy are employed to characterize the surface roughness and morphology. The deformed microstructure layers of the shot-peened specimens are investigated by using scanning electron microscopy. Experiments reveal that the fatigue life of Ti–6Al–4V is improved by the shot peening process, and the surface pre-peening polishing. The combination of pre-and post-peening polishing treatments further improves fatigue life of Ti–6Al–4V specimens. The present work provides useful guidelines for developing more efficient shot peening strategies.

关键词： Shot peening Surface polishing treatment Fatigue Residual stress Ti–6Al–4V alloy

Electrical features of radio-frequency atmospheric pressure helium discharge with and without dielectric electrodes

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Plasma Science and Technology 2019年第2期21卷 60-67页

作者： H ASHRAF S z A SHAH H i A QAzi M A KHAN S HUSSAiN M A BADAR S NiAz M SHAFiQ Department of Physics University of Sargodha Department of Physics Quaid-i-Azam University

A comparative study of radio-frequency atmospheric pressure glow discharge(rf APGD)generated in helium with and without dielectric electrodes to investigate the effect of electrodes insulation on electrical features of APGD is presented. in the α mode, both the rf APGDs remain volumetric, stable and uniform. in the γ mode, the APGD without dielectric electrodes shrinks into a constricted plasma column whereas APGD with dielectric electrodes remains stable and retains the same volume without plasma constriction even at higher densities of discharge current. A comparison of electrical features of both rf APGDs in normal and abnormal glow discharge regimes is presented. in both APGDs with and without dielectric electrodes,impedance measurements have been performed and compared with equivalent circuit *** measured impedance data is found to be in good agreement with simulated data.

关键词： radiofrequency atmospheric pressure glow discharge dielectric electrodes plasma stability control

Optimization of aerodynamic efficiency for twist morphing MAV wing

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Chinese Journal of Aeronautics 2014年第3期27卷 475-487页

作者： N.i.ismail A.H.zulkifli M.z.Abdullah M.Hisyam Basri Norazharuddin Shah Abdullah Faculty of Mechanical Engineering Universiti Teknologi MARA Shah Alam 40450 Malaysia School of Mechanical Engineering Universiti Sains Malaysia Engineering Campus Nibong Tebal 14300 Malaysia School of Materials and Mineral Resources Engineering Universiti Sains Malaysia Engineering Campus Nibong Tebal 14300Malaysia

Twist morphing （TM） is a practical control technique in micro air vehicle （MAV） flight. However, TM wing has a lower aerodynamic efficiency （CL/CD） compared to membrane and rigid wing. This is due to massive drag penalty created on TM wing, which had overwhelmed the succes- sive increase in its lift generation. Therefore, further CL/CDmax optimization on TM wing is needed to obtain the optimal condition for the morphing wing configuration. in this paper, two-way fluid- structure interaction （FSi） simulation and wind tunnel testing method are used to solve and study the basic wing aerodynamic performance over （non-optimal） TM, membrane and rigid wings. Then, a multifidelity data metamodel based design optimization （MBDO） process is adopted based on the Ansys-DesignXplorer frameworks. in the adaptive MBDO process, Kriging metamodel is used to construct the final multifidelity CL/CD responses by utilizing 23 multi-fidelity sample points from the FSi simulation and experimental data. The optimization results show that the optimal TM wing configuration is able to produce better CL/CDmax magnitude by at least 2% than the non-optimal TM wings. The flow structure formation reveals that low TV strength on the optimal TM wing induces low CD generation which in turn improves its overall CL/CDmax performance.

关键词： Aerodynamics Fluid structure interaction Micro air vehicle Optimization Twist morphing