Multiple Node Upset in SEU Hardened Storage Cells

We study the problem of multiple node upset （MNU） using three-dimensional device simulation. The results show the transient floating node and charge lateral diffusion are the key reasons for MNU. We compare the MNU with multiple bit upset （MBU）,and find that their characteristics are different. Methods to avoid MNU are also discussed.

Comparative analysis of isothermal and non-isothermal solidification of binary alloys using phase-field model

Based on the entropy function, a two-dimensional phase field model of binary alloys was established. Meanwhile, an explicit difference method with uniform grid was adopted to solve the phase field and solute field controlled equations. And the alternating direction implicit(ADI) algorithm for solving temperature field controlled equation was also employed to avoid the restriction of time step. Some characteristics of the Ni-Cu alloy were captured in the process of non-isothermal solidification, and the comparative analysis of the isothermal and the non-isothermal solidification was investigated. The simulation results indicate that the non-isothermal model is favorable to simulate the real solidification process of binary alloys, and when the thermal diffusivity decreases, the non-isothermal phase-field model is gradually consistent with the isothermal phase-field model.

Radial mixing and segregation of granular bed bi-dispersed both in particle size and density within horizontal rotating drum

Taking simultaneous variations in both particle volume and density into account, the radial mixing and segregation of binary granular bed in a rotating drum half loaded were investigated by a 3D discrete element method. Then, based on the competition theory of condensation and percolation, radial segregation due to differences in particle volume and/or density was analyzed. The results show that if either percolation effect induced by volume difference or condensation effect induced by density difference dominates in the active layer of moving bed, separation will occur. Controlling the volume ratio or density ratio of the two types of particles can achieve an equilibrium state between percolation and condensation, and then homogenous mixture can be obtained. When the percolation balances with the condensation, the relationship between volume ratioand density ratiopresents nearly a power function. Scaling up a rotating drum will not affect the mixing degree of the granular bed so long as the volume ratio and density ratio are predefined.

补血圣药阿胶

明代名士何良俊在《清森阁集》之《思生》中,做诗云:"万病皆由气血生,将相不和非敌攻。一盏阿胶常左右,扶元固本享太平。"可见,阿胶的补血功效非同一般。据说当年慈禧怀孕的时候有流产迹象,情况非常危险,很多御医都没有什么好的法子。这个时候,有位山东籍的官员递上他老家的阿胶。结果,慈禧服用了阿胶后,胎果然安住了,后来还生了个儿子,就是同治皇帝。

Influence of Zr content on microstructure and mechanical properties of implant Ti-35Nb-4Sn-6Mo-xZr alloys

The influence of Zr content on the microstructure and mechanical properties of implant Ti-35Nb-4Sn-6Mo-xZr （x=0, 3, 6, 9, 12, 15; mass fraction） alloys was investigated. It is shown that Ti-35Nb-4Sn-6Mo-xZr alloys appear to have equiaxed single β microstructure after solution treatment at 1023 K. It is found that the grains are refined first and then coarsened with the increase of Zr content. It is also found that Zr element added to titanium alloys has both the solution strengthening and fine-grain strengthening effect, and affects the lattice parameters. With increasing the Zr content of the alloys, the strength increases, the elongation decreases, whereas the elastic modulus firstly increases and then decreases. The mechanical properties of Ti-35Nb-4Sn-6Mo-9Zr alloy are as follows： σb=785 MPa, δ=11%, E=68 GPa, which is more suitable for acting as human implant materials compared to the traditional implant Ti-6Al-4V alloy.

IMPROVED ALGORITHM FOR CFD/CSD COUPLED SYSTEM DESIGN AND CALCULATION

The data information transfer and time marching strategies between computational fluid dynamics （CFD） and computational structural dynamics （CSD） play crucial roles on the aeroelastic analysis in a time domain. An improved CFD/CSD coupled system is designed, including an interpolation method and an improved loosely coupled algorithm. The interpolation method based on boundary element method （BEM） is developed to transfer aerodynamic loads and structural displacements between CFD and CSD grid systems, it can be universally used in fluid structural interaction solution by keeping energy conservation. The improved loosely coupled algo-rithm is designed, thus it improves the computational accuracy and efficiency. The new interface is performed on the two-dimensional （2-D） extrapolation and the aeroelastie response of AGARD445.6 wing. Results show that the improved interface has a superior accuracy.

驻村工作队也要“两手抓”

当前,各级党委、政府按照“三个代表”的要求,纷纷派出农村基层建设工作队进驻落后村,察访民情,为民解忧,帮扶落后村脱贫致富,这无疑是一种深受乡村干部和农民欢迎的好事。 但在实际工作中。

Influence of deformation passes on interface of SiC_p/Al composites consolidated by equal channel angular pressing and torsion

Powder mixture of pure Al and oxidized Si C was consolidated into 10%（mass fraction） Si Cp/Al composites at 250 °C by equal channel angular pressing and torsion（ECAP-T）. The valence states of Si for Si C particulates and Al for the as-consolidated composites were detected by X-ray photoelectron spectroscopy（XPS）. The interfacial bondings of the composites were characterized by scanning electron microscopy（SEM）. The elements at the interface were linearly scanned by energy dispersive spectroscopy（EDS） and the EDS mappings of Si and Al were also obtained. The values of the nanohardness at different positions within 2 μm from the boundary of Si C particulate were measured. The results show that after ECAP-T, interfacial reaction which inhibits injurious interfacial phase occurs between Al and the oxide layer of Si C, and the element interdiffusion which can enhance interfacial bonding exists between Al and Si C. As ECAP-T passes increase, the reaction degree is intensified and the element interdiffusion layer is thickened, leading to the more smooth transition of the hardness from Si C to Al.

自家血疗法在牛病诊断中的应用和机理探讨

自家血疗法在常规的皮肤消毒后,用无菌注射器抽取静脉血,不添加抗凝剂就立即注射于穴位,用于治疗某种疾病的方法。近年来,自家血疗法又改进为穴位注射疗法,除自家血疗法本身的作用外,根据经络学说和药物治疗原理,通过针刺和药物的作用,直接刺激经络上的穴位,药物在穴位处存留时间较长,故可增强与延续穴位的治疗效能。本方法治疗时,在局部形成血肿,利用血液在局部吸收较慢的原理,达到康复治疗的效果。

Isothermal section of Al-Ti-Zr ternary system at 1073 K

Through alloy sampling combined with diffusion triple technique, phase equilibria in Al-Ti-Zr ternary system at 1073 Kwere experimentally determined with electron probe microanalysis （EPMA）. Experimental results show that there is a solid solutionβ（Ti,Zr） which dissolves Al up to 16.3% （mole fraction）. Ti and Zr can substitute each other in most Ti-Al and Al-Zr binaryintermediate phases to a certain degree while the maximum solubility of Zr in Ti3Al and TiAl reaches up to 17.9% and 4.0% （molefraction）, respectively. The isothermal section consists of 16 single-phased regions, 27 two-phased regions and 14 three-phasedregions. No ternary phase was detected.

Evolution and distribution of Al_2Sm phase in as-extruded AZ61-xSm magnesium alloys during semi-solid isothermal heat-treatment

The evolution and distribution of Al2Sm phase in as-extruded AZ61-xSm（x=0, 1.5, 2.0 and 2.5, mass fraction, %） magnesium alloys during semi-solid isothermal heat treatment were investigated. The results showed that when as-extruded AZ61 magnesium alloys were modified with Sm, the smaller and rounder grains were obtained during semi-solid isothermal heat treatment. When the Sm content is 2.0%（mass fraction）, the average size of the globular grains reached the smallest value of 90 μm. Although a few Al2Sm particles existed in the α-Mg grains, most of Al2Sm particles solidified at the edge of the globular grains with the width of 20 μm. These phenomena are mainly attributed to the forces acting on Al2Sm particles in front of the solid-liquid interface, leading to Al2Sm particles accumulating at the solid-liquid interface and then solidifying at the edge of the globular grains in the quenching process.

Solid-Liquid Equilibria of trans-1,2-Cyclohexanediol＋Butyl Acetate＋ Water Ternary System

Using a laser observation technique,the solubilities of trans-1,2-cyclohexanediol in butyl acetate+wa- ter were measured at the temperature range from 298.15K to 323.15K by a synthetic method at atmospheric pres- sure.It is shown that the solubilities of trans-1,2-cyclohexanediol in butyl acetate+water were affected greatly by the proportion of butyl acetate and water,and presented maximum value at given temperature.The UNIFAC model was used to correlate the experimental data.The average relative deviation(ARD)between experimental and calculated values is 3.03%.

Analysis of barrel structure optimization for a mortar

Considering the maximum elastic limitation of the used material with newly advanced technology,the study focuses on optimization of a mortar barrel structure by thinning the wall to reduce the weight.Firstly,static analysis of barrel structure parameters is done based on finite element analysis（FEA）method and 3Dsolid model of the barrel is established based on Unigraphics NX（UG）.Secondly,the 3Dsolid model is simplified and transplanted to ANSYS for barrel wall pressure calculation.Thus,the change curves of the stress exerted on the barrel wall at different locations perpendicular to the axial direction with wall thinning are drawn.By analyzing all possible optimization schemes,the optimal design that enables the barrel to have higher bearing capacity is got.The optimized barrel structure is verified by means of fluid-solid coupling dynamic response analysis.The results show that the static analysis results are closer to real stress conditions than dynamic analysis results.Finally,the barrel weight is reduced by 13%after simulation optimization and the light weight design of the barrel is effective and reliable.

Recent developments in the use of single-atom catalysts for water splitting

Electrochemical water splitting is regarded as the most promising approach to produce hydrogen.However,the sluggish electrochemical reactions occurring at the anode and cathode,namely,the oxygen evolution reaction(OER)and the hydrogen evolution reaction(HER),respectively,consume a tremendous amount of energy,seriously hampering its wide application.Recently,single-atom catalysts(SACs)have been proposed to effectively enhance the kinetics of these two reactions.In this minireview,we focus on the recent progress in SACs for OER and HER applications.Three classes of SACs have been reviewed,i.e.,alloy-based SACs,carbon-based SACs and SACs supported on other compounds.Different factors affecting the activities of SACs are also highlighted,including the inherent element property,the coordination environment,the geometric structure and the loading amount of metal atoms.Finally,we summarize the current problems and directions for future development in SACs.

Phase equilibria of Al-Fe-Sn ternary system

The isothermal sections of Al-Fe-Sn ternary system at 973 and 593 K were determined experimentally by the equilibriated alloy method using scanning electron microscopy coupled with energy-dispersive spectrometry and X-ray diffractometry. Experimental results show that no ternary compound is found on these two sections. The maximum solubility of Fe in the liquid phase is 1.6%（mole fraction） at 973 K and those of Fe and Al in the liquid phase are 0.6% and 5.1%（mole fraction） at 593 K, respectively. The maximum solubility of Sn in the Fe-Al compounds is 4.2%（mole fraction） at 973 K and 2.3%（mole fraction） at 593 K. All the Fe-Al compounds can be in equilibrium with the liquid phase.

Prediction of Welding Deformation of Underframe

An inherent strain method was applied to the welding deformation analysis of left girder of GM’s Buick’s chassis underframe assembly. Three models are used in the calculation. Model 1 takes into account the longitudinal and transverse inherent strains; model 2 considers only longitudinal inherent strain; model 3 also takes into account the longitudinal and transverse inherent strains, but inherent strains are taken according to the function instead of the constant, for simulating the variation of the girder’s stiffness during welding process. The result shows the deformation of model 2 is less than that of the model 1, the error is less than 10% of the absolute displacement. So the longitudinal inherent strain is the main factor determining boxes-girder’s welding deformation. The deformation of model 3 is also less than that of the model 1, because the inherent strains of the model 3 are less than that of the model 1. At last, the welding deformation of the whole underframe was analyzed. The analysis results can be taken as references not only for the choices of welding sequence, welding parameters and fixture’s location, but also for welding deformation prediction of other car chassis.

Interface kinetics modeling of binary alloy solidification by considering correlation between thermodynamics and kinetics

By considering collision-limited growth mode and short-range diffusion-limited growth mode simultaneously,an extended kinetic model for solid−liquid interface with varied kinetic prefactor was developed for binary alloys.Four potential correlations arising from effective kinetics coupling the two growth modes were proposed and studied by application to planar interface migration and dendritic solidification,where the linear correlation between the effective thermodynamic driving force and the effective kinetic energy barrier seems physically realistic.A better agreement between the results of free dendritic growth model and the available experiment data for Ni−0.7at.%B alloy was obtained based on correlation between the thermodynamics and kinetics.As compared to previous models assuming constant kinetic prefactor,a common phenomenon occurring at relatively low undercoolings,i.e.the interface migration slowdown,can be ascribed to both the thermodynamic and the kinetic factors.By considering universality of the correlation between the thermodynamics and kinetics,it is concluded that the correlation should be considered to model the interface kinetics in alloy solidification.

Free dendritic growth model considering both interfacial nonisothermal nature and effect of convection for binary alloy

Considering both the effect of the nonisothermal nature of the interface as well as the effect of forced convection,an extended free dendritic growth model for binary alloys was proposed.Comparative analysis indicates that the effect of convection on solute diffusion is more remarkable compared with the ignorable effect of convection on thermal diffusion at low bath undercooling,due to the fact that solute diffusion coefficient is usually three orders of magnitude less than thermal diffusion coefficient.At high bath undercooling,the effect of convection on the dendritic growth is very slight.Furthermore,a satisfying agreement between the model predictions with the available experiment data for the Cu70Ni30 alloy was obtained,especially at low bath undercoolings,profiting from the higher values of interfacial migration velocity predicted by the present model with nonideal fluid case than that predicted by the one ignoring the effect of convection.

Phase equilibria of Co-Mo-Zn ternary system

To experimentally determine the isothermal sections of Co-Mo-Zn ternary system at 600 and 450℃,the equilibrated alloy and diffusion couple methods were adopted by using scanning electron microscopy coupled with energy-dispersive spectrometry,X-ray diffractometry and electron probe microanalysis.Experimental results show that there are six three-phase regions on the Co-Mo-Zn isothermal section at 600℃and nine three-phase regions on the Co-Mo-Zn isothermal section at 450℃.No ternary compound is found in these two isothermal sections.Both the maximum solubilities of Mo in the Co-Zn compounds(γ-Co5 Zn21,γ1-Co Zn7,γ2-Co Zn13 andβ1-Co Zn)and that of Zn inε-Co3 Mo are no more than 1.5 at.%.The maximum solubilities of Zn inμ-Co7 Mo6 are determined to be 2.1 at.%and 2.7 at.%at 600 and 450℃,respectively.In addition,the maximum solubilities of Co in MoZn7 and MoZn22 are 0.5 at.%and 4.7 at.%at 450℃,respectively.