Nonlinear dynamics of angle-ply composite laminated thin plate with third-order shear deformation

An asymptotic perturbation method is presented based on the Fourier expansion and temporal rescaling to investigate the nonlinear oscillations and chaotic dynamics of a simply supported angle-ply composite laminated rectangular thin plate with parametric and external excitations. According to the Reddy’s third-order plate theory, the governing equations of motion for the angle-ply composite laminated rectangular thin plate are derived by using the Hamilton’s principle. Then, the Galerkin procedure is applie...     

Complex dynamics of functionally graded plates with thermal load in 1:2 internal resonance

Complex dynamics of the simply-supported functionally graded (FG) rectangular plates with thermal load is investigated. Based on Reddy’s third-order shear deformation theory and the von Karman nonlinear strain-displacement relations, ordinary differential equations (ODEs) of the plate’s transversal oscillation are derived by using Hamilton’s principle and Galerkin’s approach. Solutions’ classification of the equations in 1:2 internal resonance is analyzed. Particular results of a simply- supported aluminum-...     

Understanding of the influence of process parameters on the heat transfer behavior at the metal/die interface in high pressure die casting process

The current paper focuses on the influence of the process parameters on the peak values of the interfacial heat transfer coefficient(IHTC)at metal/die interface during high pressure die casting(HPDC)process.A"step shape"casting and AM50 alloy were used during the experiment.The IHTC was determined by solving the inverse thermal problem based on the measured temperature inside the die.Results show that the initial die surface temperature(IDST,TDI)has a dominant influence while the casting pressure and fast shot velocity have a secondary influence on the IHTC peak values.By curve fitting,it was found that the IHTC peak value(hmax)changes as a function of the IDST in a manner of hmax=e αTγ DI .Such relationship between the IHTC peak value and the IDST can also be found when the casting alloy is ADC12,indicating that this phenomenon is a common characteristic in the HPDC process.     

Delayed Hopf bifurcation in time-delayed slow-fast systems

This paper presents an investigation on the phenomenon of delayed bifurcation in time-delayed slow-fast differential systems. Here the two delayed’s have different meanings. The delayed bifurcation means that the bifurcation does not happen immediately at the bifurcation point as the bifurcation parameter passes through some bifurcation point, but at some other point which is above the bifurcation point by an obvious distance. In a time-delayed system, the evolution of the system depends not only on the pre...     

Preparation of TiO_2 thin film by the LPD method on functionalized organic self-assembled monolayers

In this paper,uniform titania(TiO2) films have been formed at 50°C on silanol SAMs by the liquid-phase deposition(LPD) method at a temperature below 100℃.OTS(Octadecyltrichloro-Silane) self-assembled monolayers(SAMs) on glass wafers were used as substrates for the deposition of titanium dioxide thin films.This functionalized organic surface has shown to be effective for promoting the growth of films from titanic aqueous solutions by the LPD method at a low temperature below 100°C.The crystal phase composition,microstructure and topography of the as-prepared films were characterized by various techniques,including X-ray diffraction(XRD) ,scanning electron microscopy(SEM) ,and atomic force microscopy(AFM) .The results indicate that the as-prepared thin films are purely crystallized anatase TiO2 constituted by nanorods after being annealed at 500°C.The pH values,concentration of reactants,and deposition temperatures play important roles in the growth of TiO2 thin films.     

Energy spectrum of an electron confined in the hexagon-shaped quantum well

Considering the hexagonal-shaped quantum-scale formations on the surface of thin semiconductor films,a methodology was developed to obtain the analytical solution of the Schrdinger equation when impenetrable walls of a quantum well are treated as mirrors.The results obtained allowed the calculation of the space probability distributions and the energy spectrum of the particle confined in a hexagonal-shaped well.     

Straight SiO_x nanorod Y junctions

Novel straight silicon oxideSiOx(1x2) nanorod Y junctions have been synthesized on Si plate by thermal evaporation of mixed powders of silica and carbon nanofibers at 1300°C and condensation on a Si substrate without assistance of any catalyst.The synthesized samples were characterized by means of scanning electron microscopy,transmission electron microscopy,high resolution transmission electron microscopy,and energy dispersive X-ray spectroscopy.The results suggested that the straight nanorod Y junctions are amorphous and consist only of elements Si and O,and these rods with diameters about 50-200 nm have a neat smooth surface.The growth of such silicon oxide nanorods may be a result of the second nucleation on the surface of rods causing a change in the growth direction of silicon oxide nanorods developed.     

Effects of Ti,Al and Hf on niobium silcides formation in the Nb-Si in situ composites

The effects of alloying elements Ti,Al and Hf on niobium silicides formation in the Nb-Si in situ composites have been investigated by scanning electron microscopy(SEM) ,X-ray diffraction(XRD) and transmission electron microscopy(TEM) .The binary,ternary and multicomponent alloys have been fabricated by vacuum non-consumable arc melting method.The results show that Ti tends to stabilize Nb3Si phase,while Al promotes the direct formation ofβ-Nb5Si3 phase with a tetrahedral D8m structure.Exceptionally,it seems that Hf is beneficial to the formation ofγ-Nb5Si3 phase with a hexangular D88 structure.For the multicomponent Nb-Si in situ composites,the cooperative effects of different elements on niobium silicides formation basically maintain the character of ternary system.     

Comparison of short period InAs/GaSb superlattices on GaSb and GaAs substrates

Type Ⅱ superlattices(SLs) short period InAs(4ML)/GaSb(8ML) were grown by molecular-beam epitaxy on lattice-mismatched GaAs substrates and on GaSb substrates.A smooth GaSb epilayer was formed on GaAs substrates by inserting mulit-buffer layers including an interfacial misfit mode AlSb quantum dot layer and AlSb/GaSb superlattices smooth layer.SLs grown on GaAs substrates(GaAs-based SLs) showed well-resolved satellite peaks in XRD.GaSb-based SLs with better structural quality and smoother surface showed strong photoluminescence at 2.55μm with a full width at half maximum(FWHM) of 20 meV,narrower than 31 meV of GaAs-based SLs.Inferior optical absorption of GaAs-based SL was observed in the range of 2-3μm. Photoresponse of GaSb-based SLs showed the cut-off wavelength at 2.6μm.     

Microstructure and texture evolution during warm compression of the magnesium alloy AZ31

The evolution of the microstructure and texture with strain during compression at 150℃of the magnesium alloy AZ31 has been investigated using the electron backscattered diffraction(EBSD)technique.The initial samples were chosen to have a strong basal plane texture with the crystal c-axes perpendicular to the compression direction.The EBSD data provide evidence concerning the relative activity of both{10-12}extension twinning and slip,and suggest that non-basalc+a slip is important in samples deformed to a strain of more than 0.2.The relative contributions of the twinning and the slip during deformation have been discussed based on the results above.     

再论十字路口上的现代教育制度

The modern educational institution is approaching a new cross-roads,the most new sign of which is creation of GATS in the process of the Uruguay Round (1987-1994).That GATS included educational service means that education industry,marketing and trade has been a general trend at present on the world. However,most people from both Chinese and world's educational circles don't get ready enough.That is best opportunity for Chinese education to make a leaping over development.     

Effect of Fe(Ⅲ) impurity on the electrochemical performance of LiFePO_4 prepared by hydrothermal process

Lithium iron phosphate(LiFePO4)was synthesized from LiOH,FeSO4 and H3PO4 by a hydrothermal process at 180℃.The samples were characterized by X-ray diffraction,scanning electron microscopy and chemical analysis.Electrochemical performance of the samples was tested in terms of charge-discharge capacity and cycling behavior.The results indicated that Fe(Ⅲ) impurity had obviously effect on the electrochemical properties of LiFePO4,and the formation of Fe 3+ was caused by the oxidation of Fe 2+ in the dissolving...     

Phase reaction of Au/Sn solder bonding for GaN-based vertical structure light emitting diodes

Au/Sn solder bonding on Si substrates was used to fabricate the GaN-based vertical structure light emitting diodes (VSLEDs). The phase reaction of Au/Sn solder under different bonding conditions was investigated by the measurement of electron back scattering diffraction (EBSD), and the characteristics of VSLED were analyzed by scanning acoustic microscope (SAM), Raman scattering, current-voltage (I-V) and light output-current (L-I) curves. After the bonding process, horizontal stripes of Au/Sn phase (δ phas...     

Effect of the silicon powder content on the properties of Al_2O_3-SiC-Me composites

By means of transient plastic phase process,the Al2O3-SiC-Me composites were produced throungh adding metal aluminium and silicon-powder to Al2O3-SiC materials.Under the condition of the same content of silicon and aluminium mixed-powder,the effect of silicon powder addition on properties of Al2O3-SiC-Me composites was studied by means of XRD and EPMA analyses in the temperature range of 300°C-1600°C.The results indicated that the content of metal phase in the sample at 1600°C increases with increasing silicon powder content.At the same time,when the temperature is lower than 1100°C,the strength of samples gradually increases with increasing temperature.However when the temperature is higher than 11000°C,the strength of samples gradually decreases with increasing temperature,and this change is very small.The results also indicated that at the same sintering temperature,the sample with 6%silicon powder has the maximum strength.     

Performance of an activated carbon made from waste palm shell in simultaneous adsorption of SO_x and NO_x of flue gas at low temperature

This study examined the individual and simultaneous adsorption of SOx(SO2)and NOx(NO-NO2)on activated carbon prepared from waste palm shell.The adsorption process was examined in a fixed bed reactor at low temperatures(100 300°C).For individual adsorption without any catalytic activation,SOx showed good adsorption whereas NOx was very much poor.In the simultaneous adsorption of SOx and NOx,SOx showed greater adsorption affinity than NOx.For palm shell activated carbon(PSAC)impregnated with metal catalyst(Ni and Ce)the concentration adsorbed profile showed that the amount of SOx adsorbed decreased regularly,while the amount of the adsorbed NOx increased irregularly.The properties of the pure and impregnated PSAC were analyzed by BET,SEM and EDX.These investigations indicated that PSAC impregnated with metal catalyst is the determining factor in the adsorption of SOx and NOx simultaneously.     

Effect of one-step aging on microstructure and properties of a novel Al-Zn-Mg-Cu-Zr alloy

The effect of one-step aging temper on the mechanical properties,electrical conductivity and the microstructure of a novel Al-7.5Zn-1.6Mg-1.4Cu-0.12Zr alloy has been investigated.The results indicated that with elevating the aging temperature from 100°C to 160°C,the aging response rate was greatly accelerated,and the UTS at peak aging condition decreased,while the corresponding TYS increased.However,the electrical conductivity of the alloy became higher.After aging for 24 h at 120°C,the peak UTS and TYS values were achieved as 591 MPa and 541 MPa,respectively;but the alloy achieved a lower conductivity,20.4 MS/m.When T6 temper was performed at 140°C for 14 h,the UTS decreased only by 1%of the former,whereas the TYS and the electrical conductivity increased obviously,which were up to 559 MPa and 22.6 MS/m,respectively.The major strengthening precipitates of the peak-aged alloy were GP zones andη′phase.The precipitates in both the matrix and the grain boundary became coarser with rising aging temperature.There were obvious PFZs along the grain boundary both in T6 conditions aged at 140°C and 160°C.     

Optimization of the process for preparing Al-doped ZnO thin films by sol-gel method

Transparent and conducting Al-doped ZnO thin films with c-axis-preferred orientation were prepared on glass substrate via sol-gel route.The physical and chemical changes during thermal treatment were analyzed by TG-DSC spectra and the crystallization quality was characterized by XRD patterns.The optimized preheating and post-heating temperatures were determined at～420°C and～530°C,respectively.From thermodynamic and kinetics views,we investigated the mechanism of orientation growth with(002) plane parallel to the substrates.The surface morphologies of the films,post-heated at 420°C,450°C,530°C and 550°C,respectively,were observed by SEM micrographs.The film post-heated at 530°C shows a homogenous dense microstructure and exhibits the minimum sheet resistance of 140Ω/Sq.The visible optical transmittance of all the films is beyond 90%.In addition,the annealing treatment in vacuum can contribute greatly to the electrical conductivity.     

Examination of dynamic recrystallization during compression of AZ31 magnesium

This study aimed to investigate dynamic recrystallization(DRX)behavior during compression of magnesium alloy AZ31. Cylinder samples were cut from the extruded rod and hot rolled sheet AZ31 for compression test.The samples were compressed using a Gleeble 1500D at a temperature of 300℃and a strain rate of 0.01 s-1.Grain orientations and misorientation angles across grain boundaries for the tested samples were obtained by using electron backscatter diffraction(EBSD)technique.The results showed that strong basal texture was observed after 50%compression(ε=0.69)on both the extruded and hot rolled samples,which have different initial textures.It was observed that with increased strain,DRX grains gradually rotated to basal orientation,and grain boundaries with misorientation angle of near 30°was formed in the samples.At the strain of 0.69,a high fraction of high-angle(60°)boundaries was present in the extruded sample,whereas almost no high angle boundaries were observed in the hot rolled sheet sample.     

Inducing effect of Pb(Zr_(0.4)Ti_(0.6))O_3 thin film derived by different processes in BiFeO_3/Pb(Zr_(0.4)Ti_(0.6))O_3 multilayer capacitor at room temperature

BiFeO3/PZT multilayer capacitor was prepared on Pt(100) /Ti/SiO2/Si(100) substrate.PZT buffer layer was derived by MOCVD method(label:PZT1) and sputtering method(label:PZT2) respectively.XRD analysis indicated that high(110) orientation of BFO in the BFO/PZT1 structure was achieved.SEM analysis indicated a better microstructure in the BFO/PZT1 structure compared with BFO/PZT2.The remnant polarization of the BFO/PZT1 was 82.5μC/cm2 at an applied voltage of 8 V,compared with that of 25.2μC/cm2 in the BFO/PZT 2 structure.The BFO/PZT1 multilayer exhibited little polarization fatigue(1.5%) upon 1×101 0switching cycles,at an applied voltage of 4 V.The leakage current density was about 2×10-7A/cm 2 at an applied voltage 4 V,in the BFO/PZT1 capacitor.All the results indicated that PZT can act as an inducing layer to the BFO and the MOCVD derived PZT has more inducing effect to the BFO thin film at room temperature.     

A combinatorial approach of developing alloy thin films using co-sputtering technique for displays

In this study we have used a combinatorial approach for producing binary and ternary alloy thin film libraries using a lab-scale RF co-sputtering system.Initially we used two elemental sputtering targets,i.e.aluminum(Al) target and neodymium(Nd) target,to produce a film library of varying composition and successfully identified a suitable composition range(1.95-2.38 at%Nd) in which resistance to hillock formation and resistivity of the film spots were found to be satisfactory in annealed state(350°C,30 min) .In another case,in order to form ternary alloy composition library we have used two sputtering targets,i.e.an Al-0.5 at%Nd alloy target and an elemental Ni target.Though,co-sputtered Al-0.6 at% Nd-0.9 at%Ni alloy films showed satisfactory resistance to hillock formation and low resistivity after annealing,film deposited from a ternary alloy target with the same composition failed to show satisfactory resistance to hillock formation during annealing.In case of Al-0.6 at%Nd-0.9 at%Ni alloy target,250 nm thick film showed poor resistance to hillock formation than the 500 nm thick film.This clearly showed thickness-dependent hillock performance of Al-0.6 at%Nd-0.9 at%Ni alloy.In this study it was found that,in addition to the process variables,metallurgical microstructure of the alloy sputtering targets had significant effect on the film properties which was not obvious from the results of films deposited using co-sputtering of the individual elemental targets.