The Al foil for high voltage Al electrolytic capacitor usage was immersed in 5.0%NaOH solution containing trace amount of Zn2＋and Zn was chemically plated on its surface through an immersion-reduction reaction. Such ...The Al foil for high voltage Al electrolytic capacitor usage was immersed in 5.0%NaOH solution containing trace amount of Zn2＋and Zn was chemically plated on its surface through an immersion-reduction reaction. Such Zn-deposited Al foil was quickly transferred into HCl-H 2 SO 4 solution for DC-etching. The effects of Zn impurity on the surface and cross-section etching morphologies and electrochemical behavior of Al foil were investigated by SEM, polarization curve （PC） and electrochemical impedance spectroscopy （EIS）. The special capacitance of 100 V formation voltage of etched foil was measured. The results show that the chemical plating Zn on Al substrate in alkali solution can reduce the pitting corrosion resistance, enhance the pitting current density and improve the density and uniform distribution of pits and tunnels due to formation of the micro Zn-Al galvanic local cells. The special capacitance of etched foil grows with the increase of Zn2＋concentration.展开更多
Dilation angle is a significant parameter needed for numerical simulation of tunnels.Even though dilation parameter is physically variable and dependent on confinement and experienced shear plastic strain based on the...Dilation angle is a significant parameter needed for numerical simulation of tunnels.Even though dilation parameter is physically variable and dependent on confinement and experienced shear plastic strain based on the existing dilation models,numerical simulations of tunnels and underground openings with constant dilation parameter usually lead to satisfactory results in practical use.This study aims to find out why constant dilation angle is enough under practical conditions to simulate numerically tunnels and underground excavations in spite of the fact that dilation angle is variable in laboratory and experimental scale.With this aim,this work studies how mobilized dilation angle varies in a plastic zone surrounding a tunnel.For the circular tunnel under uniform in situ stress field,the stepwise finite difference approximation analytical solution considering strain softening rock mass behavior with mobilized dilation angle was used to study how mobilized dilation angle varies in plastic zone around tunnel under very different conditions.In practical conditions determined in this study,dilative behavior of all over the plastic zone around the tunnel can be approximated to constant dilation angle in the middle region of the plastic zone.Moreover,the plastic zone displacements for mobilized and constant dilation angle models are compared with each other.Further investigation under more general non-uniform in situ stress conditions and non-circular tunnels is performed by using the commercial finite difference software to numerically simulate the Mine-by experimental tunnel of AECL(Atomic Energy of Canada Limited)and the arched tunnel.Although the Mine-by and arched tunnels were numerically simulated based on the mobilized dilation angle model,the variability associated with dilation angle around the simulated Mine-by and arched tunnels is insignificant,and dilation angle is approximately constant in the plastic zone.展开更多
When a block of dense sandy soil moves downhill, the shear-induced soil dilatancy along the basal shear boundary produces a negative value of excess pore pressure that increases the basal frictional resistance. Dilata...When a block of dense sandy soil moves downhill, the shear-induced soil dilatancy along the basal shear boundary produces a negative value of excess pore pressure that increases the basal frictional resistance. Dilatancy angle,Ψ, the degree to which the basal soil dilates due to the shear, normally evolves during slope failure. A study by other researchers shows that if Ψ is constant, the block of dense soil will remain stable(or unstable) sliding when the velocity-weakening rate of the basal friction coefficient of the block is small(or large) enough. Moreover, during unstable sliding processes, the block of dense soil exhibits "periodic" patterns of intermittent slipping. Here, we used a more efficient and accurate numerical scheme to revisit that study. We expanded their model by assuming Ψ evolves during slope failure. Consequently, we acquired completely different results. For instance, even though the velocity-weakening rate of the friction coefficient is fixed at the same smaller(or larger) value that those researchers use, the stable(or unstable) steady states of landslide they predict will inversely change to unstable(or stable) when Ψ decreases(or increases) with the increase of slide displacement to a value small(or large) enough. Particularly, in unstable processes, the soil block exhibits "aperiodic" styles of intermittent slipping, instead of "periodic". We found out that the stick states appearing later last longer(or shorter) in the case of decreasing(or increasing) Ψ. Moreover, because the basic states of landslides with impacts of dilatancy evolution are not steady nor periodic, traditional stability-analysis methods cannot be "directly" used to analyze the stability of such landslides. Here, we broke through this technical problem to a degree. We showed that combining a concept called "quasi-steady-state approximation" with a traditional stability-analysis technique can qualitatively predict the instability onset of the landslides. Through this study, we demonstrated that the combination of Chebyshev collocation(CC) and 4^(th)-order Runge-Kutta methods is more accurate and efficient than the numerical scheme those researchers use.展开更多
The general behavior of micron-particles in the inner domain of porous ceramic vessel was simulated by computational fluid dynamics software in terms of sampling experimental data.The results show that there is an opt...The general behavior of micron-particles in the inner domain of porous ceramic vessel was simulated by computational fluid dynamics software in terms of sampling experimental data.The results show that there is an optimum porosity of 0.32 to get a higher efficiency and lower pressure drop during filtration.According to the results of simulation and experiment,it is evident that lower inlet velocity can maintain lower pressure drop and obtain higher collection efficiency and inlet concentration also has a crucial influence on the collection efficiency.The collection efficiency of equipment increases significantly with the increase of inlet concentration when the inlet concentration is less than 6.3 g/m3,but it gradually tends to be stable in the range of 97.3%-99.7%when the inlet concentration is over this concentration.展开更多
A new insight into the constant current-constant voltage （CC-CV） charge protocol based on the spherical diffusion model was presented. From the model, the CV-charge process compensates, to a large extent, the capaci...A new insight into the constant current-constant voltage （CC-CV） charge protocol based on the spherical diffusion model was presented. From the model, the CV-charge process compensates, to a large extent, the capacity loss in the CC process, and the capacity loss increases with increasing the charging rate and decreases with increasing the lithium-ion diffusion coefficient and using a smaller r value （smaller particle-size and larger diffusion coefficient） and a lower charge rate will be helpful to decreasing the capacity loss. The results show that the CC and the CV charging processes, in some way, are complementary and the capacity loss during the CC charging process due to the large electrochemical polarization can be effectively compensated from the CV charging process.展开更多
The thermodynamic properties of LiBC are investigated by using the full-potential linearlzed muffin-tin orbital method （FP-LMTO） within the frame of density functional theory （DFT） and using the quasi-harmonic Deb...The thermodynamic properties of LiBC are investigated by using the full-potential linearlzed muffin-tin orbital method （FP-LMTO） within the frame of density functional theory （DFT） and using the quasi-harmonic Debye model. The dependencies of the normalized lattice parameters a/a0 and c/c0, the ratio （c/a）/2, the normalized primitive volume V/V0 on pressure and temperature are successfully obtained. It is found that the interlayer covalent interactions （Li-B bonds or Li-C bonds） are more sensitive to temperature and pressure than intralayer ones （B-C bonds）, as gives rise to the extreme lattice anisotropy in the bulk hop LiBC.展开更多
Thermal diffusivity, specific heat capacity and thermal conductivity of AI86Gd6TM8 （TM = Cu, Ni, Co, Fe, Mn, Cr, Ti, Zr, Mo, Ta） glass-forming alloys in the temperature range of 300-880 K were determined by laser fl...Thermal diffusivity, specific heat capacity and thermal conductivity of AI86Gd6TM8 （TM = Cu, Ni, Co, Fe, Mn, Cr, Ti, Zr, Mo, Ta） glass-forming alloys in the temperature range of 300-880 K were determined by laser flash method. The temperatures of endothermic and exothermic reactions of the alloys were determined by differential scanning calorimetry method. The alloys were prepared by conventional arc-melting technique under helium atmosphere. All the alloys studied exhibit strong supercooling of the liquidus temperatures up to 80 K, which indicates their good glass-forming ability. The specific heat capacity of the alloys achieves the Dulong-Petit＇s value in the temperature range of 350-550 K except Als6CrsGd6 and Als6ZrsGd6 compositions. The values of both thermal diffusivity and thermal conductivity of the alloy studied are significantly lower than those for pure aluminum. It is found that embedding 14% （mole fraction） of transition elements （Gd＋TM） in the aluminum matrix leads to significant decrease in the absolute magnitudes of both thermal diffusivity and thermal conductivity in crystalline state. The thermal conductivity of glass-forming Als6Gd6TMs alloys is strongly affected by directed chemical bonding between alloy components.展开更多
A revised displacement discontinuity method(DDM) program is developed for the simulation of rock joint propagation and dilatancy analysis. The non-linear joint model used in the program adopts Barton-Bandis normal def...A revised displacement discontinuity method(DDM) program is developed for the simulation of rock joint propagation and dilatancy analysis. The non-linear joint model used in the program adopts Barton-Bandis normal deformation model, Kulhaway shear deformation model and Mohr-Coulomb criterion. The joint propagation criterion is based on the equivalent stress intensity factor which can be obtained by regression analysis. The simulated rock joint propagation accords well with the existing knowledge. The closure and opening of joint is investigated by DDM, and it is shown that if the opening volume of propagated joint is larger than closure volume of the old joint, the joint dilatancy occurs. The dilatancy condition is mainly controlled by the normal stiffness of the rock joint. When the normal stiffness is larger than the critical value, joint dilatancy occurs. The critical normal stiffness of rock joint changes with the joint-load angle, and joint dilatancy is most possible to occur at 30°.展开更多
Diffusion coefficients of chloride ions in four soils of different texture with varying effective moisture content and varying bulk density from 1.1 to 1.6 g cm3 under three different temperatures were determined by t...Diffusion coefficients of chloride ions in four soils of different texture with varying effective moisture content and varying bulk density from 1.1 to 1.6 g cm3 under three different temperatures were determined by the diffusion-cell method using 36Cl-labelled CaCl2 solution. The results showed that activation energy decreased with water content, which indicated that the threshold for diffusion was lower at a higher soil moisture rate. Therefore, the diffusion coefficient (D) of chloride ions in soil increased consistently with soil moisture. Although a near linear increase in the diffusion coefficient with increasing soil moisture or bulk density in all the soils was observed, the increase rate in different soils was not the same. The D value increased with temperature, and with temperature increased by 10℃ in the range from 5 "C to 45℃ theD valve increased by 10%～30%, averaging about 20%.展开更多
The characteristic properties of shell element with similar shapes are used to generate a so-called super element for the analysis of the crack problems for cylindrical pressure vessels. The formulation is processed b...The characteristic properties of shell element with similar shapes are used to generate a so-called super element for the analysis of the crack problems for cylindrical pressure vessels. The formulation is processed by matrix condensation without the involvement of special treatment. This method can deal with various singularity problems and it also presents excellent results to crack problems for cylindrical shell. Especially,the knowledge of the kind of singular order is not necessary in super element generation; it is very economical in terms of computer memory and programming. This method also exhibits versatility to solve the problem of kinked crack at cylindrical shell.展开更多
Driven by an ever-increasing num- ber of new services and applications, transport networks have been undergoing significant changes. In this paper, we describe several ex- citing technology directions associated with ...Driven by an ever-increasing num- ber of new services and applications, transport networks have been undergoing significant changes. In this paper, we describe several ex- citing technology directions associated with future optical transport networks. We review the status of 100G, which is now commercially available and entering volume deployments, and its applications in China. Beyond 100G is considered as the primary technology for the expansion of both channel and fiber capacity in tile near term, and several enabling techniques are introduced. Then, key technologies, prod- ucts, and future evolutionary options of Optical Transport Networks （OTNs） are extensively discussed. Compared to fixed bandwidth and coarse granularity of current WDM network, a flexible grid architecture is a desirable evolu- tion trend, and key technologies and challenges are described. Finally, we illustrate the multi-dimension convergences in terms of IP and optical, Packet OTN （P-OTN）, as well as Electronic Integrated Circuits （EICs） and Photonic Integrated Cimuits （PICs）. Transport networks are therefore in the process of be- coming more broadband, robust, flexible, cost-effective and lower-power-consumptive.展开更多
基金Project (51172102) supported by the National Natural Science Foundation of ChinaProject (BS2011CL011) supported by Promotive Research Fund for Young and Middle-aged Scientists of Shandong Province(doctor fund),China
文摘The Al foil for high voltage Al electrolytic capacitor usage was immersed in 5.0%NaOH solution containing trace amount of Zn2＋and Zn was chemically plated on its surface through an immersion-reduction reaction. Such Zn-deposited Al foil was quickly transferred into HCl-H 2 SO 4 solution for DC-etching. The effects of Zn impurity on the surface and cross-section etching morphologies and electrochemical behavior of Al foil were investigated by SEM, polarization curve （PC） and electrochemical impedance spectroscopy （EIS）. The special capacitance of 100 V formation voltage of etched foil was measured. The results show that the chemical plating Zn on Al substrate in alkali solution can reduce the pitting corrosion resistance, enhance the pitting current density and improve the density and uniform distribution of pits and tunnels due to formation of the micro Zn-Al galvanic local cells. The special capacitance of etched foil grows with the increase of Zn2＋concentration.
文摘Dilation angle is a significant parameter needed for numerical simulation of tunnels.Even though dilation parameter is physically variable and dependent on confinement and experienced shear plastic strain based on the existing dilation models,numerical simulations of tunnels and underground openings with constant dilation parameter usually lead to satisfactory results in practical use.This study aims to find out why constant dilation angle is enough under practical conditions to simulate numerically tunnels and underground excavations in spite of the fact that dilation angle is variable in laboratory and experimental scale.With this aim,this work studies how mobilized dilation angle varies in a plastic zone surrounding a tunnel.For the circular tunnel under uniform in situ stress field,the stepwise finite difference approximation analytical solution considering strain softening rock mass behavior with mobilized dilation angle was used to study how mobilized dilation angle varies in plastic zone around tunnel under very different conditions.In practical conditions determined in this study,dilative behavior of all over the plastic zone around the tunnel can be approximated to constant dilation angle in the middle region of the plastic zone.Moreover,the plastic zone displacements for mobilized and constant dilation angle models are compared with each other.Further investigation under more general non-uniform in situ stress conditions and non-circular tunnels is performed by using the commercial finite difference software to numerically simulate the Mine-by experimental tunnel of AECL(Atomic Energy of Canada Limited)and the arched tunnel.Although the Mine-by and arched tunnels were numerically simulated based on the mobilized dilation angle model,the variability associated with dilation angle around the simulated Mine-by and arched tunnels is insignificant,and dilation angle is approximately constant in the plastic zone.
基金financial support with the Grant No. MOST 105-2911-I-006-301
文摘When a block of dense sandy soil moves downhill, the shear-induced soil dilatancy along the basal shear boundary produces a negative value of excess pore pressure that increases the basal frictional resistance. Dilatancy angle,Ψ, the degree to which the basal soil dilates due to the shear, normally evolves during slope failure. A study by other researchers shows that if Ψ is constant, the block of dense soil will remain stable(or unstable) sliding when the velocity-weakening rate of the basal friction coefficient of the block is small(or large) enough. Moreover, during unstable sliding processes, the block of dense soil exhibits "periodic" patterns of intermittent slipping. Here, we used a more efficient and accurate numerical scheme to revisit that study. We expanded their model by assuming Ψ evolves during slope failure. Consequently, we acquired completely different results. For instance, even though the velocity-weakening rate of the friction coefficient is fixed at the same smaller(or larger) value that those researchers use, the stable(or unstable) steady states of landslide they predict will inversely change to unstable(or stable) when Ψ decreases(or increases) with the increase of slide displacement to a value small(or large) enough. Particularly, in unstable processes, the soil block exhibits "aperiodic" styles of intermittent slipping, instead of "periodic". We found out that the stick states appearing later last longer(or shorter) in the case of decreasing(or increasing) Ψ. Moreover, because the basic states of landslides with impacts of dilatancy evolution are not steady nor periodic, traditional stability-analysis methods cannot be "directly" used to analyze the stability of such landslides. Here, we broke through this technical problem to a degree. We showed that combining a concept called "quasi-steady-state approximation" with a traditional stability-analysis technique can qualitatively predict the instability onset of the landslides. Through this study, we demonstrated that the combination of Chebyshev collocation(CC) and 4^(th)-order Runge-Kutta methods is more accurate and efficient than the numerical scheme those researchers use.
基金Project(50878080)supported by the National Natural Science Foundation of ChinaProject(K0902006-31)supported by the Key Scientific and Technological Special of Changsha City in China
文摘The general behavior of micron-particles in the inner domain of porous ceramic vessel was simulated by computational fluid dynamics software in terms of sampling experimental data.The results show that there is an optimum porosity of 0.32 to get a higher efficiency and lower pressure drop during filtration.According to the results of simulation and experiment,it is evident that lower inlet velocity can maintain lower pressure drop and obtain higher collection efficiency and inlet concentration also has a crucial influence on the collection efficiency.The collection efficiency of equipment increases significantly with the increase of inlet concentration when the inlet concentration is less than 6.3 g/m3,but it gradually tends to be stable in the range of 97.3%-99.7%when the inlet concentration is over this concentration.
基金Projects(20676152, 20876178) supported by the National Natural Science Foundation of China
文摘A new insight into the constant current-constant voltage （CC-CV） charge protocol based on the spherical diffusion model was presented. From the model, the CV-charge process compensates, to a large extent, the capacity loss in the CC process, and the capacity loss increases with increasing the charging rate and decreases with increasing the lithium-ion diffusion coefficient and using a smaller r value （smaller particle-size and larger diffusion coefficient） and a lower charge rate will be helpful to decreasing the capacity loss. The results show that the CC and the CV charging processes, in some way, are complementary and the capacity loss during the CC charging process due to the large electrochemical polarization can be effectively compensated from the CV charging process.
基金The project supported by National Natural Science Foundation of China under Grant No. 10576020
文摘The thermodynamic properties of LiBC are investigated by using the full-potential linearlzed muffin-tin orbital method （FP-LMTO） within the frame of density functional theory （DFT） and using the quasi-harmonic Debye model. The dependencies of the normalized lattice parameters a/a0 and c/c0, the ratio （c/a）/2, the normalized primitive volume V/V0 on pressure and temperature are successfully obtained. It is found that the interlayer covalent interactions （Li-B bonds or Li-C bonds） are more sensitive to temperature and pressure than intralayer ones （B-C bonds）, as gives rise to the extreme lattice anisotropy in the bulk hop LiBC.
基金Project(13-02-96036) supported by RFBR and the Government of Sverdlovsk Region of Russia
文摘Thermal diffusivity, specific heat capacity and thermal conductivity of AI86Gd6TM8 （TM = Cu, Ni, Co, Fe, Mn, Cr, Ti, Zr, Mo, Ta） glass-forming alloys in the temperature range of 300-880 K were determined by laser flash method. The temperatures of endothermic and exothermic reactions of the alloys were determined by differential scanning calorimetry method. The alloys were prepared by conventional arc-melting technique under helium atmosphere. All the alloys studied exhibit strong supercooling of the liquidus temperatures up to 80 K, which indicates their good glass-forming ability. The specific heat capacity of the alloys achieves the Dulong-Petit＇s value in the temperature range of 350-550 K except Als6CrsGd6 and Als6ZrsGd6 compositions. The values of both thermal diffusivity and thermal conductivity of the alloy studied are significantly lower than those for pure aluminum. It is found that embedding 14% （mole fraction） of transition elements （Gd＋TM） in the aluminum matrix leads to significant decrease in the absolute magnitudes of both thermal diffusivity and thermal conductivity in crystalline state. The thermal conductivity of glass-forming Als6Gd6TMs alloys is strongly affected by directed chemical bonding between alloy components.
基金Project(2009318000046) supported by the Western Transport Technical Program of the Ministry of Transport,China
文摘A revised displacement discontinuity method(DDM) program is developed for the simulation of rock joint propagation and dilatancy analysis. The non-linear joint model used in the program adopts Barton-Bandis normal deformation model, Kulhaway shear deformation model and Mohr-Coulomb criterion. The joint propagation criterion is based on the equivalent stress intensity factor which can be obtained by regression analysis. The simulated rock joint propagation accords well with the existing knowledge. The closure and opening of joint is investigated by DDM, and it is shown that if the opening volume of propagated joint is larger than closure volume of the old joint, the joint dilatancy occurs. The dilatancy condition is mainly controlled by the normal stiffness of the rock joint. When the normal stiffness is larger than the critical value, joint dilatancy occurs. The critical normal stiffness of rock joint changes with the joint-load angle, and joint dilatancy is most possible to occur at 30°.
文摘Diffusion coefficients of chloride ions in four soils of different texture with varying effective moisture content and varying bulk density from 1.1 to 1.6 g cm3 under three different temperatures were determined by the diffusion-cell method using 36Cl-labelled CaCl2 solution. The results showed that activation energy decreased with water content, which indicated that the threshold for diffusion was lower at a higher soil moisture rate. Therefore, the diffusion coefficient (D) of chloride ions in soil increased consistently with soil moisture. Although a near linear increase in the diffusion coefficient with increasing soil moisture or bulk density in all the soils was observed, the increase rate in different soils was not the same. The D value increased with temperature, and with temperature increased by 10℃ in the range from 5 "C to 45℃ theD valve increased by 10%～30%, averaging about 20%.
基金Project (No. NSC-95-2221-E-167-002) supported by the National Science Council of Taiwan, China
文摘The characteristic properties of shell element with similar shapes are used to generate a so-called super element for the analysis of the crack problems for cylindrical pressure vessels. The formulation is processed by matrix condensation without the involvement of special treatment. This method can deal with various singularity problems and it also presents excellent results to crack problems for cylindrical shell. Especially,the knowledge of the kind of singular order is not necessary in super element generation; it is very economical in terms of computer memory and programming. This method also exhibits versatility to solve the problem of kinked crack at cylindrical shell.
基金supported by the National Natural Science Foundation of China under GrantNo. 61171076National 863 Project underGrant No. 2012AA011303National 973 Project under Grant No. 2010CB328200(2010CB328201)
文摘Driven by an ever-increasing num- ber of new services and applications, transport networks have been undergoing significant changes. In this paper, we describe several ex- citing technology directions associated with future optical transport networks. We review the status of 100G, which is now commercially available and entering volume deployments, and its applications in China. Beyond 100G is considered as the primary technology for the expansion of both channel and fiber capacity in tile near term, and several enabling techniques are introduced. Then, key technologies, prod- ucts, and future evolutionary options of Optical Transport Networks （OTNs） are extensively discussed. Compared to fixed bandwidth and coarse granularity of current WDM network, a flexible grid architecture is a desirable evolu- tion trend, and key technologies and challenges are described. Finally, we illustrate the multi-dimension convergences in terms of IP and optical, Packet OTN （P-OTN）, as well as Electronic Integrated Circuits （EICs） and Photonic Integrated Cimuits （PICs）. Transport networks are therefore in the process of be- coming more broadband, robust, flexible, cost-effective and lower-power-consumptive.
