Effects of magnetic fields on Fe-Si composite electrodeposition

Coatings containing Fe-Si particles were electrodeposited on 3.0wt% Si steel sheets under magnetic fields. The effects of magnetic flux density （MFD）, electrode arrangement and current density on the surface morphology, the silicon content in the coatings and the cathode current efficiency were investigated. When a magnetic field was applied parallel to the current and when the MFD was less than 0.5 T, numerous needle-like structures appeared on the coating surface. With increasing MFD, the needle-like structures weakened and were transformed into dome-shaped structures. Meanwhile, compared to results obtained in the absence of a magnetic field, the silicon content in the coatings significantly increased as the MFD was increased for all of the samples obtained using a vertical electrode system. However, in the case of an aclinic electrode system, the silicon content decreased. Furthermore, the cathode current efficiency was considerably diminished when a magnetic field was applied. A possible mechanism for these phenomena was discussed.     

Effect of substrate doping on threshold voltages of buried channel pMOSFET based on strained-SiGe technology

The effect of substrate doping on the threshold voltages of buried channel pMOSFET based on strained-SiGe technology was studied. By physically deriving the models of the threshold voltages, it is found that the layer which inversely occurs first is substrate doping dependent, giving explanation for the variation of plateau observed in theC-V characteristics of this device, as the doping concentration increases. The threshold voltages obtained from the proposed model are-1.2805 V for buried channel and-2.9358 V for surface channel at a lightly doping case, and-3.41 V for surface channel at a heavily doping case, which agrees well with the experimental results. Also, the variations of the threshold voltages with several device parameters are discussed, which provides valuable reference to the designers of strained-SiGe devices.     

Effect of partition coefficient on microsegregation during solidification of aluminium alloys

In the modeling of microsegregation, the partition coefficient is usually calculated using data from the equilibrium phase diagrams. The aim of this study was to experimentally and theoretically analyze the partition coefficient in binary aluminum--copper alloys. The sam- ples were analyzed by differential thermal analysis （DTA）, which were melted and quenched from different temperatures during solidifica- tion. The mass fraction and composition of phases were measured by image processing and scanning electron microscopy （SEM） equipped with an energy-dispersive X-ray spectroscopy （EDS） unit. These data were used to calculate as the experimental partition coefficients with four different methods. The experimental and equilibrium partition coefficients were used to model the concentration profile in the primary phase. The modeling results show that the profiles calculated by the experimental partition coefficients are more consistent with the experi- mental profiles, compared to those calculated using the equilibrium partition coefficients.     

Large-scale two-dimensional nonlinear FE analysis on PGA amplification effect with depth and focusing effect of Fuzhou Basin

Based on the explicit finite element（FE） method and platform of ABAQUS,considering both the inhomogeneity of soils and concave-convex fluctuation of topography,a large-scale refined two-dimensional（2D） FE nonlinear analytical model for Fuzhou Basin was established.The peak ground motion acceleration（PGA） and focusing effect with depth were analyzed.Meanwhile,the results by wave propagation of one-dimensional（1D） layered medium equivalent linearization method were added for contrast.The results show that：1） PGA at different depths are obviously amplified compared to the input ground motion,amplification effect of both funnel-shaped depression and upheaval areas（based on the shape of bedrock surface） present especially remarkable.The 2D results indicate that the PGA displays a non-monotonic decreasing with depth and a greater focusing effect of some particular layers,while the 1D results turn out that the PGA decreases with depth,except that PGA at few particular depth increases abruptly; 2） To the funnel-shaped depression areas,PGA amplification effect above 8 m depth shows relatively larger,to the upheaval areas,PGA amplification effect from 15 m to 25 m depth seems more significant.However,the regularities of the PGA amplification effect could hardly be found in the rest areas; 3） It appears a higher regression rate of PGA amplification coefficient with depth when under a smaller input motion; 4） The frequency spectral characteristic of input motion has noticeable effects on PGA amplification tendency.     

Simulation of bidirectional pedestrian flow in transfer station corridor based on multi forces

A good understanding of pedestrian movement in the transfer corridor is vital for the planning and design of the station, especially for efficiency and safety.A multi-force vector grid model was presented to simulate the movement of bidirectional pedestrian flow based on cellular automata and forces between pedestrians. The model improves rule-based characteristics of cellular automata, details forces between pedestrians and solves pedestrian collisions by a several-step updating method to simulate pedestrian movements. Two general scenarios in corridor were simulated. One is bidirectional pedestrian flow simulation with isolation facility, and the other is bidirectional pedestrian flow simulation without isolation facility, where there exists disturbance in the middle. Through simulation, some facts can be seen that pedestrians in the case with isolation facility have the largest speed and pedestrians in the case without isolation facility have the smallest speed; pedestrians in the case of unidirectional flow have the largest volume and pedestrians in the case of without isolation facility have the smallest volume.     

Influence of plasma on the densification mechanism of SPS under multi-field effect

The densification mechanism of an Fe-based alloy powder containing tiny oxide particles under the synergic multi-field effect of spark plasma sintering （SPS） was investigated. Metallographic microscopy and scanning electron microscopy were used to observe the morphology of samples sintered at different temperatures, and the temperature dislribution in an individual spherical powder particle during sintering was calculated in consideration of the influence of plasma, which was qualified and quantified through the analysis of the U-Icurve. The plasma was observed to play a substantial role in activating and heating the samples at the very early stage of sintering, whereas the joule-heat effect played a dominant role during sintering. Moreover, the plasma also facilitated the diffusion and migration of materials for neck formation.     

Effects of sintering temperature on the microstructural evolution and wear behavior of WCp reinforced Ni-based coatings

This article focuses on the microstructural evolution and wear behavior of 50wt%WC reinforced Ni-based composites prepared onto 304 stainless steel substrates by vacuum sintering at different sintering temperatures. The microstructure and chemical composition of the coatings were investigated by X-ray diffraction （XRD）, differential thermal analysis （DTA）, scanning and transmission electron microscopy （SEM and TEM） equipped with energy-dispersive X-ray spectroscopy （EDS）. The wear resistance of the coatings was tested by thrust washer testing. The mechanisms of the decomposition, dissolution, and precipitation of primary carbides, and their influences on the wear resistance have been discussed. The results indicate that the coating sintered at 1175℃ is composed of fine WC particles, coarse M6C （M=Ni, Fe, Co, etc.） carbides, and discrete borides dispersed in solid solution. Upon increasing the sintering temperature to 1225℃, the microstructure reveals few incompletely dissolved WC particles trapped in larger M6C, Cr-rich lamellar M23C6, and M3C2 in the austenite matrix. M23C6 and M3C2 precipitates are formed in both the γ/M6C grain boundary and the matrix. These large-sized and lamellar brittle phases tend to weaken the wear resistance of the composite coatings. The wear behavior is controlled simultaneously by both abrasive wear and adhesive wear. Among them, abrasive wear plays a major role in the wear process of the coating sintered at 1175℃, while the effect of adhesive wear is predominant in the coating sintered at 1225℃.     

Effects of environmental factors on corrosion behaviors of metal-fiber porous components in a simulated direct methanol fuel cell environment

Abstract： To enable the use of metallic components in direct methanol fuel cells （DMFCs）, issues related to corrosion resistance must be considered because of an acid environment induced by the solid electrolyte. In this study, we report the electrochemical behaviors of metal-fiber-based porous sintered components in a simulated corrosive environment of DMFCs. Three materials were evaluated： pure copper, AISI304, and AISI316L. The environmental factors and related mechanisms affecting the corrosion behaviors were analyzed. The results demonstrated that AISI316L exhibits the best performance. A higher SO4^2- concentration increases the risk of material corrosion, whereas an increase in methanol concentration inhibits corrosion. The morphological features of the corroded samples were also characterized in this study.     

フライアッシュを用いたコンクリ一トの中性化に及ぼす暴露条件の影響

This report gathered measurement results about the carbonation of concrete using fly-ash. In Series Ⅰ, comparison among outdoor exposure area, the type of fly-ash and replacement ratio was made. In Series Ⅱ, comparison among the direction of the test piece, exposure place, exposure condition and mixture proportions was made. As a result of this experiment in Series Ⅰ, there were no large differences in carbonation between the outdoor exposure areas, the ratio of indoor by outdoor were smaller than the fact-finding results of the past, in addition in the case of same water-binder ratio, there were no differences in the coefficient of carbonation rate between the fly-ash type. In Series Ⅱ, in the case of outdoor exposure, the coefficient of carbonation rate was larger at with roof than without roof, and was smaller at the north side of the building than south side.     

Numerical calculation on solar temperature field of a cable-stayed bridge with U-shaped section on high-speed railway

Based on transient temperature field theory of heat conduction, the solar temperature field calculation model of U-shape sectioned high-speed railway cable-stayed bridge under actions of concrete beams and ballast was established. Using parametric programming language, finite element calculation modules considering climate conditions, bridge site, structure dimension and material thermophysical properties were compiled. Six standard day cycles with the strongest yearly radiation among the bridge sites were selected for sectional solar temperature field calculation and temperature distributions under different temperature-sensitive parameters were compared. The results show that under the influence of sunshine, U-shape section of the beam shows obvious nonlinear distribution characteristics and the maximum cross-section temperature difference is more than 21℃; the ballast significantly reduces sunshine temperature difference of the beam and temperature peak of the bottom margin lags with the increase of ballast thickness; the maximum cross-section vertical temperature gradient appears in summer while large transverse temperature difference appears in winter.     

Effect of annealing on the microstructure and mechanical properties of Mg-2.5Zn-0.5Y alloy

The microstructure and mechanical properties of extruded Mg-2.5Zn-0.5Y alloy before and after annealing treatments were investigated. The as-extruded alloy exhibits a yield tensile strength （YTS） of 305.9 MPa and an ultimate tensile strength （UTS） of 354.8 MPa, whereas the elongation is only 4%. After annealing, the YTS and UTS decrease to 150 MPa and 240 MPa, respectively, and the elongation increases to 28%. Interestingly, the annealed alloy maintains an acceptable stress level even after a much higher ductility is achieved. These excellent mechanical properties stem from the combined effects of fine α-Mg dynamic recrystallization （DRX） grains and a homogeneously distributed icosahedral quasicrystalline phase （I-phase） in the α-Mg DRX grains. In particular, the superior ductility originates from the coherent interface of I-phase and α-Mg and from the formation of the secondary twin {101 1}-{101 2}（38°〈1 2 10〉） in the tension twin {1012}.     

Influence of silicon on the microstructures,mechanical properties and stretch-flangeability of dual phase steels

Uniaxial tension tests and hole-expansion tests were carried out to determine the influence of silicon on the microstructures, mechanical properties, and stretch-flangeability of conventional dual-phase steels. Compared to 0.03wt% silicon, the addition of 1.08wt% silicon induced the formation of finer ferrite grains （6.8μm ） and a higher carbon content of martensite （Cm≈ 0.32wt%）. AS the silicon level increased, the initial strain-hardening rate （n value） and the uniform elongation increased, whereas the yield strength, yield ratio, and stretch-flangeability decreased. The microstructures were observed after hole-expansion tests. The results showed that low carbon content martensite （Cm ≈ 0.19wt%） can easily deform in coordination with ferrite. The relationship between the mechanical properties and stretch-flangeability indicated that the steel with large post-uniform elongation has good stretch-flangeability due to a closer plastic incom- patibility of the ferrite and martensite phases, which can effectively delay the production and decohesion of microvoids.     

Effect of fiber angle on LYP steel shear walls behavior简

Steel shear wall（SSW） was properly determined using numerical and experimental approaches.The properties of SSW and LYP（low yield point） steel shear wall（LSSW） were measured.It is revealed that LSSW exhibits higher properties compared to SSW in both elastic and inelastic zones.It is also concluded that the addition of CFRP（carbon fiber reinforced polymers） enhances the seismic parameters of LSSW（stiffness,energy absorption,shear capacity,over strength values）.Also,stress values applied to boundary frames are lower due to post buckling forces.The effect of fiber angle was also studied and presented as a mathematical equation.     

and transformation of nitrobenzene in Songhua River and calculation of flux and remnant based on quantification analysis

To evaluate the long-term environmental effect of the nitrobenzene precipitated into Songhua River caused by the explosion accident of CNPC Jilin Petrochemical Company, we have proved that three selected cross sections were all in a completely mixed state which was not affected by the neighborhood flow firstly. The research of the main flux of contaminants indicates that the nitrobenzene flux in all cross sections is less and less, and the attenuation trend is gradually slowing down. From the residual remnant of nitrobenzene in different segments calculated according to the related experimental data, we suppose that parts of nitrobenzene remnant are transferred by the bottom sludge adsorption and resolution. A general analysis model was set up from the one-dimensional counter-flow equation, and functions of atmosphere-water exchange process, deposit-water interaction, and river turbulent mixing and dissemination. The results of this quantification analysis are different from the real calculation, while the gross transformation trend is the same, which indicates that both analyses are based on reality and can reflect the transport and transformation of nitrobenzene actually.     

Mechanical response of transmission lines based on sliding cable element

In order to study the sliding characteristics when the cable is connected with the other rods in the transmission line structures, a linear sliding cable element based on updated Lagrangian formulation and a sliding catenary element considering the out-of-plane stiffness coefficient are put forward. A two-span and a three-span cable structures are taken as examples to verify the sliding cable elements. By comparing the tensions of the two proposed cable elements with the existing research results, the error is less than 1%, which proves the correctness of the proposed elements. The sliding characteristics should be considered in the practical engineering because of the significant difference between the tensions of sliding cable elements and those of cable element without considering sliding. The out-of-plane stiffness coefficient and friction characteristics do not obviously affect the cable tensions.     

Parametric study on collapse margin ratio of structure

The determination of collapse margin ratio （CMR） of structure is influenced by many uncertain factors. Some factors that can affect the calculation ofCMR, e.g., the elongation of the structural fundamental period prior to collapse, the determination of earthquake intensity measure, the seismic hazard probability, and the difference of the spectral shapes between the median spectrum of the ground motions and the design spectrum, were discussed. Considering the elongation of the structural fundamental period, the intensity measureSa（T1） should be replaced with＊aS in the calculation of CMR for short-period and medium-period structures. The reasonable intensity measure should be determined by the correlation analysis between the earthquake intensity measure and the damage index of the structure. Otherwise, CMR should be adjusted according to the seismic hazard probability and the difference in the spectral shapes. For important long-period structures, CMR should be determined by the special site spectrum. The results indicate that bothSa（T1） and spectrum intensity （SI） could be used as intensity measures in the calculation of CMR for medium-period structures, but SI would be a better choice for long-period structures. Moreover, an adjusted CMR that reflects the actual seismic collapse safety of structures is provided.     

Desulfurization ability of refining slag with medium basicity

The desulfurization ability of refining slag with relative lower basicity （B） and Al2O3 content （B = 3.5-5.0; 20wt%-25wt% Al2O3） was studied. Firstly, the component activities and sulfide capacity （Cs） of the slag were calculated. Then slag-metal equilibrium experiments were carried out to measure the equilibrium sulfur distribution （Ls）. Based on the laboratorial experiments, slag composition was optimized for a better desulfurization ability, which was verified by industrial trials in a steel plant. The obtained results indicated that an MgO-saturated CaO-Al2O3-SiO2-MgO system with the basicity of about 3.5-5.0 and the Al2O3 content in the range of 20wt%-25wt% has high activity of CaO （αCaO）, with no deterioration of Cs compared with conventional desulfurization slag. The measured Ls between high-strength low-alloyed （HSLA） steel and slag with a basicity of about 3.5 and an Al2O3 content of about 20wt% and between HSLA steel and slag with a basicity of about 5.0 and an Al2O3 content of about 25wt% is 350 and 275, respectively. The new slag with a basicity of about 3.5-5.0 and an Al2O3 content of about 20wt% has strong desulfurization ability. In particular, the key for high-efficiency desulfurization is to keep oxygen potential in the reaction system as low as possible, which was also verified by industrial trials.     

Effect of acicular ferrite on banded structures in low-carbon microalloyed steel

The effect of acicular ferrite （AF） on banded structures in low-carbon microalloyed steel with Mn segregation during both iso- thermal transformation and continuous cooling processes was studied by dilatometry and microscopic observation. With respect to the iso- thermal transformation process, the specimen isothermed at 550℃ consisted of AF in Mn-poor bands and martensite in Mn-rich bands, whereas the specimen isothermed at 450℃ exhibited two different morphologies of AF that appeared as bands. At a continuous cooling rate in the range of 4 to 50℃/s, a mixture of AF and martensite formed in both segregated bands, and the volume fraction of martensite in Mn-rich bands was always higher than that in Mn-poor bands. An increased cooling rate resulted in a decrease in the difference of martensite volume fraction between Mn-rich and Mn-poor bands and thereby leaded to less distinct microstrucmral banding. The results show that Mn segregation and cooling rate strongly affect the formation of AF-containing banded structures. The formation mechanism of microstructural banding was also discussed.     

Influence of gangue existing states in iron ores on the formation and flow of liquid phase during sintering

Gangue existing states largely affect the high-temperature characteristics of iron ores. Using a micro-sintering method and scan- ning electron microscopy, the effects of gangue content, gangue type, and gangue size on the assimilation characteristics and fluidity of liquid phase of five different iron ores were analyzed in this study. Next, the mechanism based on the reaction between gangues and sintering mate- dais was unraveled. The results show that, as the SiO2 levels increase in the iron ores, the lowest assimilation temperature （LAT） decreases, whereas the index of fluidity of liquid phase （IFL） increases. Below 1.5wt%, Al2O3 benefits the assimilation reaction, but higher concentra- tions proved detrimental. Larger quartz particles increase the SiO2 levels at the local reaction interface between the iron ore and CaO, thereby reducing the LAT. Quartz-gibbsite is more conductive to assimilation than kaolin. Quartz-gibbsite and kaolin gangues encourage the forma- tion of liquid-phase low-Al2O3-SFCA with high IFL and high-Al2O3-SFCA with low IFL, respectively.     

Modeling the effects of ore properties on water recovery in the thickening process

A better understanding of solid-liquid separation would assist in improving the thickening performance and perhaps water recovery as well. The present work aimed to develop an empirical model to study the effects of ore properties on the thickening process based on pilot tests using a column. A hydro-cyclone was used to prepare the required samples for the experiments. The model significantly predicted the experimental underflow solid content using a regression equation at a given solid flux and bed level for different samples, indicating that ore properties are the effective parameters in the thickening process. This work confirned that the water recovery would be increased about 5% by separating the feed into two parts, overflow and underflow, and introducing two different thickeners into them separately. This is duo to the fact that thickeners are limited by permeability and compressibility in operating conditions.