The ultrasonic echo in liquid density measurement often suffers noise,which makes it difficult to obtain the useful echo waveform,resulting in low accuracy of density measurement.A denoising method based on improved v...The ultrasonic echo in liquid density measurement often suffers noise,which makes it difficult to obtain the useful echo waveform,resulting in low accuracy of density measurement.A denoising method based on improved variational mode decomposition(VMD)for noise echo signals is proposed.The number of decomposition layers of the traditional VMD is hard to determine,therefore,the center frequency similarity factor is firstly constructed and used as the judgment criterion to select the number of VMD decomposition layers adaptively;Secondly,VMD algorithm is used to decompose the echo signal into several modal components with a single modal component,and the useful echo components are extracted based on the features of the ultrasonic emission signal;Finally,the liquid density is calculated by extracting the amplitude and time of the echo from the modal components.The simulation results show that using the improved VMD to decompose the echo signal not only can improve the signal-to-noise ratio of the echo signal to 20.64 dB,but also can accurately obtain the echo information such as time and amplitude.Compared with the ensemble empirical mode decomposition(EEMD),this method effectively suppresses the modal aliasing,keeps the details of the signal to the maximum extent while suppressing noise,and improves the accuracy of the liquid density measurement.The density measurement accuracy can reach 0.21%of full scale.展开更多
The density of liquid Incone1718 alloy was experimentally measured by electrostatic levitation technique, where the maximum undercooling of 100 K was realized for the commercial sample. The measured density of liquid ...The density of liquid Incone1718 alloy was experimentally measured by electrostatic levitation technique, where the maximum undercooling of 100 K was realized for the commercial sample. The measured density of liquid lnconel 718 alloy is 7.39 g cm^-3 at the liquidus temperature of 1663 K which was confirmed by DSC experiment, with the linear temperature coefficient of -6.89 × 10^-4 gcm^-3 K^-1. Correspondingly, four ternary Ni-Cr-Fe compositions were designed to simulate the density of liquid lnconel 718 alloy with 16000 atoms, from which the liquid structure is revealed by pair distribution function, The predicted result shows a remarkable enhancement with the decrease of temperature at the first neighbor distance.展开更多
The accurate measurement on the compressibility and thermal expansion coefficients of density standard liquid at 2329kg/m3（DSL-2329） plays an important role in the quality control for silicon single crystal manufact...The accurate measurement on the compressibility and thermal expansion coefficients of density standard liquid at 2329kg/m3（DSL-2329） plays an important role in the quality control for silicon single crystal manufacturing. A new method is developed based on hydrostatic suspension principle in order to determine the two coefficients with high measurement accuracy. Two silicon single crystal samples with known density are immersed into a sealed vessel full of DSL-2329. The density of liquid is adjusted with varying liquid temperature and static pressure, so that the hydrostatic suspension of two silicon single crystal samples is achieved. The compression and thermal expansion coefficients are then calculated by using the data of temperature and static pressure at the suspension state. One silicon single crystal sample can be suspended at different state, as long as the liquid temperature and static pressure function linearly according to a certain mathematical relationship. A hydrostatic suspension experimental system is devised with the maximal temperature control error ±50 μK; Silicon single crystal samples can be suspended by adapting the pressure following the PID method. By using the method based on hydrostatic suspension principle, the two key coefficients can be measured at the same time, and measurement precision can be improved due to avoiding the influence of liquid surface tension. This method was further validated experimentally, where the mixture of 1, 2, 3-tribromopropane and 1,2-dibromoethane is used as DSL-2329. The compressibility and thermal expansion coefficients were measured, as 8.5′10–4 K–1 and 5.4′10–10 Pa–1, respectively.展开更多
In aluminum-copper alloy, the segregation has a severe bad effect on the alloying degree, strength and corrosion resistance. A deeper understanding of element segregation behavior will have a great signif icance on th...In aluminum-copper alloy, the segregation has a severe bad effect on the alloying degree, strength and corrosion resistance. A deeper understanding of element segregation behavior will have a great signif icance on the prevention of segregation. In the study, the element segregation behavior of ZL205 A aluminum-copper alloy was investigated by examining isothermally solidifi ed samples using scanning electron microscopy and energy dispersive spectroscopy. The calculated results of segregation coeffi cients show that Cu and Mn are negative segregation elements; while Ti, V and Zr are positive segregation elements. The sequence of element segregation degree from the greatest to the least in ZL205 A alloy is Cu, Mn, V, Ti, Zr and Al. The density of residual liquid is expected to increase with a decrease in the quenching temperature ranging from 630 ℃ to 550 ℃. The calculated results conf irm that the quenching temperature has an insignif icant effect on the liquid density; and the variation of density is mainly due to element segregation. Consequently, segregations of Al, Cu and Mn lead to an increase in density, but Ti, V and Zr present the opposite effect. The contribution of each element to the variation of the liquid density was analyzed. The sequence of contributions of alloying elements to the variation of total liquid density is Cu>Al>Mn>V>Ti>Zr.展开更多
The microstructure and composition of the residual liquid at different temperatures were investigated by scanning electron microscopy （SEM） and energy dispersive X-ray spectrometer （EDX） associated with the Thermo...The microstructure and composition of the residual liquid at different temperatures were investigated by scanning electron microscopy （SEM） and energy dispersive X-ray spectrometer （EDX） associated with the Thermo-calc software calculation of the equilibrium phase diagrams of Inconel 718 and segregated liquid. The liquid density difference and Rayleigh number variation during solidification were estimated as well. It is found that the heavy segregation of Nb in liquid prompts the precipitation of δ and Laves phase directly from liquid and the resultant quenched liquid microstructure consists of pro-eutectic γ＋eutectic,or complete eutectic according to the content of Nb from low to high. The liquid density increases with decreasing temperature during the solidification of Inconel 718 and the liquid density difference is positive. The largest relative Rayleigh number occurs at 1320°C when the liquid fraction is about 40vol%.展开更多
An electrolyte Equation of State is presented by combining the Cubic Plus Association Equation of State,Mean Spherical Approximation and the Born equation.This new model uses experimental relative static permittivity,...An electrolyte Equation of State is presented by combining the Cubic Plus Association Equation of State,Mean Spherical Approximation and the Born equation.This new model uses experimental relative static permittivity,intend to predict well the activity coefficients of individual ions(ACI)and liquid densities of aqueous solutions.This new model is applied to model water+Na Cl binary system and water+gas+Na Cl ternary systems.The cation/anion-water interaction parameters of are obtained by fitting the experimental data of ACI,mean ionic activity coefficients(MIAC)and liquid densities of water+Na Cl binary system.The cation/anion-gas interaction parameters are obtained by fitting the experimental data of gas solubilities in aqueous Na Cl solutions.The modeling results show that this new model can correlate well with the phase equilibrium and volumetric properties.Without gas,predictions for ACI,MIAC,and liquid densities present relative average deviations of 1.3%,3.6%and 1.4%compared to experimental reference values.For most gas-containing systems,predictions for gas solubilities present relative average deviations lower than 7.0%.Further,the contributions of ACI,and salting effects of Na Cl on gases are analyzed and discussed.展开更多
Physical properties including refractive index, density, viscosity and conductivity for binary mixtures of l-butyl- 3-methyl imidazolium chloride （[BMIM]CI） and different organic solvents at 298.15 K have been inves...Physical properties including refractive index, density, viscosity and conductivity for binary mixtures of l-butyl- 3-methyl imidazolium chloride （[BMIM]CI） and different organic solvents at 298.15 K have been investigated. Ex- cess molar volumes have been calculated and obtained data has been fitted by the Redlich-Kister equation. The density and refractive index were found to increase with increasing concentration of [BMIM]CI, however, excep- tions do exist as in the case of dimethyl sulfoxide （DMSO）/[BMIM]CI. For DMSO/[BMIM]CI, the density decreases with increasing concentration. The addition of different organic solvents was able to disrupt the interactions within mixtures, leading to free mobility of ions. The free mobility of ions has been found to enhance conductivity and decrease viscosity to varying extents in all mixtures studied. It has been observed that solubility parameters, dielectric constants and composition of the solvents used play a vital role in determining the resultant properties. The data obtained will play an important role in understanding the effect of the addition of organic solvents in ILs to enhance their applicability.展开更多
The conventional Rackett model for predicting liquid molar volume has been modified to cater for the effect of molar composition of the Deep Eutectic Solvents(DES). The experimental molar volume data for a group of co...The conventional Rackett model for predicting liquid molar volume has been modified to cater for the effect of molar composition of the Deep Eutectic Solvents(DES). The experimental molar volume data for a group of commonly used DES has been used for optimizing the improved model. The data involved different molar compositions of each DES. The validation of the new model was performed on another set of DESs. The average relative deviation of the model on the training and validation datasets was approximately 0.1% while the Rackett model gave a relative deviation of more than 1.6%. The modified model deals with variations in DES molar composition and temperature in a more consistent way than the original Rackett model which exhibits monotonic performance degradation as temperature moves away from reference conditions. Having the composition of the DES as a model variable enhances the practical utilization of the predicting model in diverse design and process simulation applications.展开更多
Chemotaxonomy based on diagnostic pigments is now a routine tool for macroscopic determination of the composition and abundance of phytoplankton in various aquatic environments. Since the taxonomic capability of this ...Chemotaxonomy based on diagnostic pigments is now a routine tool for macroscopic determination of the composition and abundance of phytoplankton in various aquatic environments. Since the taxonomic capability of this method depends on the relationships between diagnostic pigments and chlorophyll a of classified groups, it is critical to calibrate it by using pigment relationships obtained from representative and/or dominant species local to targeted investigation area. In this study, pigment profiles of 31 harmful algal bloom(HAB) species isolated from the coastal sea areas of China were analyzed with high performance liquid chromatography(HPLC). Pigment compositions, cellular pigment densities and ratios of pigments to chlorophyll a were determined and calculated. Among all these species, 25 kinds of pigments were detected, of which fucoxanthin, peridinin, 19'-butanoyloxyfucoxanthin, 19'-hexanoyloxyfucoxanthin, violaxanthin, and antheraxanthin were diagnostic pigments. Cellular pigment density was basically independent of species and environmental conditions, and therefore was recommended as a bridge to compare the results of HPLC-CHEMTAX technique with the traditional microscopy method. Pigment ratios of algal species isolated from the coast of China, especially the diagnostic pigment ratios, were higher than those from other locations. According to these results, pigment ratio ranges of four classes of phytoplankton common off the coast of China were summarized for using in the current chemotaxonomic method. Moreover, the differences of pigments ratios among different species under the same culturing conditions were consistent with their biological differences. Such differences have the potential to be used to classify the phytoplankton below class, which is meaningful for monitoring HABs by HPLC-CHEMTAX.展开更多
The mathematical equations of 2-D thermal density flow in a channel were developed and a finite layer numerical model was established. In the direction of y, a cubic spline approximations were used for u and θ, and l...The mathematical equations of 2-D thermal density flow in a channel were developed and a finite layer numerical model was established. In the direction of y, a cubic spline approximations were used for u and θ, and linear interpolation were used for du/dx and dθ/dx. The integration of differential equations along the direction of y was made with the subdomain scheme of weighted residual method. In the direction of x, the boundary value problem of differential equations was converted into an initial value problem. It is then solved by shooting method. An effective method for choosing and amending shooting multipoint initial values have been presented. The vertical distribution of u and θ at each x-section were also obtained.展开更多
Manipulation of antiferromagnetic(AFM) spins by electrical means is on great demand to develop the AFM spintronics with low power consumption. Here we report a reversible electrical control of antiferromagnetic moment...Manipulation of antiferromagnetic(AFM) spins by electrical means is on great demand to develop the AFM spintronics with low power consumption. Here we report a reversible electrical control of antiferromagnetic moments of FeMn up to 15 nm, using an ionic liquid to exert a substantial electric-field effect. The manipulation is demonstrated by the modulation of exchange spring in[Co/Pt]/FeMn system, where AFM moments in FeMn pin the magnetization rotation of Co/Pt. By carrier injection or extraction,the magnetic anisotropy of the top layer in FeMn is modulated to influence the whole exchange spring and then passes its influence to the [Co/Pt]/FeMn interface, through a distance up to the length of exchange spring that fully screens electric field. Comparing FeMn to IrMn, despite the opposite dependence of exchange bias on gate voltages, the same correlation between carrier density and exchange spring stiffness is demonstrated. Besides the fundamental significance of modulating the spin structures in metallic AFM via all-electrical fashion, the present finding would advance the development of low-power-consumption AFM spintronics.展开更多
文摘The ultrasonic echo in liquid density measurement often suffers noise,which makes it difficult to obtain the useful echo waveform,resulting in low accuracy of density measurement.A denoising method based on improved variational mode decomposition(VMD)for noise echo signals is proposed.The number of decomposition layers of the traditional VMD is hard to determine,therefore,the center frequency similarity factor is firstly constructed and used as the judgment criterion to select the number of VMD decomposition layers adaptively;Secondly,VMD algorithm is used to decompose the echo signal into several modal components with a single modal component,and the useful echo components are extracted based on the features of the ultrasonic emission signal;Finally,the liquid density is calculated by extracting the amplitude and time of the echo from the modal components.The simulation results show that using the improved VMD to decompose the echo signal not only can improve the signal-to-noise ratio of the echo signal to 20.64 dB,but also can accurately obtain the echo information such as time and amplitude.Compared with the ensemble empirical mode decomposition(EEMD),this method effectively suppresses the modal aliasing,keeps the details of the signal to the maximum extent while suppressing noise,and improves the accuracy of the liquid density measurement.The density measurement accuracy can reach 0.21%of full scale.
基金financially supported by the National Natural Science Foundation of China (Grant Nos. 51327901, 51474175, 51522102 and 51734008)
文摘The density of liquid Incone1718 alloy was experimentally measured by electrostatic levitation technique, where the maximum undercooling of 100 K was realized for the commercial sample. The measured density of liquid lnconel 718 alloy is 7.39 g cm^-3 at the liquidus temperature of 1663 K which was confirmed by DSC experiment, with the linear temperature coefficient of -6.89 × 10^-4 gcm^-3 K^-1. Correspondingly, four ternary Ni-Cr-Fe compositions were designed to simulate the density of liquid lnconel 718 alloy with 16000 atoms, from which the liquid structure is revealed by pair distribution function, The predicted result shows a remarkable enhancement with the decrease of temperature at the first neighbor distance.
基金Supported by National Natural Science Foundation of China(Grant No.51105347)National Key Technology R&D Program of Ministry of Science and Technology of China(Grant No.2011BAI02B03)
文摘The accurate measurement on the compressibility and thermal expansion coefficients of density standard liquid at 2329kg/m3（DSL-2329） plays an important role in the quality control for silicon single crystal manufacturing. A new method is developed based on hydrostatic suspension principle in order to determine the two coefficients with high measurement accuracy. Two silicon single crystal samples with known density are immersed into a sealed vessel full of DSL-2329. The density of liquid is adjusted with varying liquid temperature and static pressure, so that the hydrostatic suspension of two silicon single crystal samples is achieved. The compression and thermal expansion coefficients are then calculated by using the data of temperature and static pressure at the suspension state. One silicon single crystal sample can be suspended at different state, as long as the liquid temperature and static pressure function linearly according to a certain mathematical relationship. A hydrostatic suspension experimental system is devised with the maximal temperature control error ±50 μK; Silicon single crystal samples can be suspended by adapting the pressure following the PID method. By using the method based on hydrostatic suspension principle, the two key coefficients can be measured at the same time, and measurement precision can be improved due to avoiding the influence of liquid surface tension. This method was further validated experimentally, where the mixture of 1, 2, 3-tribromopropane and 1,2-dibromoethane is used as DSL-2329. The compressibility and thermal expansion coefficients were measured, as 8.5′10–4 K–1 and 5.4′10–10 Pa–1, respectively.
基金financially supported by the National Natural Science Foundation of China(Grant No.51375391)
文摘In aluminum-copper alloy, the segregation has a severe bad effect on the alloying degree, strength and corrosion resistance. A deeper understanding of element segregation behavior will have a great signif icance on the prevention of segregation. In the study, the element segregation behavior of ZL205 A aluminum-copper alloy was investigated by examining isothermally solidifi ed samples using scanning electron microscopy and energy dispersive spectroscopy. The calculated results of segregation coeffi cients show that Cu and Mn are negative segregation elements; while Ti, V and Zr are positive segregation elements. The sequence of element segregation degree from the greatest to the least in ZL205 A alloy is Cu, Mn, V, Ti, Zr and Al. The density of residual liquid is expected to increase with a decrease in the quenching temperature ranging from 630 ℃ to 550 ℃. The calculated results conf irm that the quenching temperature has an insignif icant effect on the liquid density; and the variation of density is mainly due to element segregation. Consequently, segregations of Al, Cu and Mn lead to an increase in density, but Ti, V and Zr present the opposite effect. The contribution of each element to the variation of the liquid density was analyzed. The sequence of contributions of alloying elements to the variation of total liquid density is Cu>Al>Mn>V>Ti>Zr.
文摘The microstructure and composition of the residual liquid at different temperatures were investigated by scanning electron microscopy （SEM） and energy dispersive X-ray spectrometer （EDX） associated with the Thermo-calc software calculation of the equilibrium phase diagrams of Inconel 718 and segregated liquid. The liquid density difference and Rayleigh number variation during solidification were estimated as well. It is found that the heavy segregation of Nb in liquid prompts the precipitation of δ and Laves phase directly from liquid and the resultant quenched liquid microstructure consists of pro-eutectic γ＋eutectic,or complete eutectic according to the content of Nb from low to high. The liquid density increases with decreasing temperature during the solidification of Inconel 718 and the liquid density difference is positive. The largest relative Rayleigh number occurs at 1320°C when the liquid fraction is about 40vol%.
文摘An electrolyte Equation of State is presented by combining the Cubic Plus Association Equation of State,Mean Spherical Approximation and the Born equation.This new model uses experimental relative static permittivity,intend to predict well the activity coefficients of individual ions(ACI)and liquid densities of aqueous solutions.This new model is applied to model water+Na Cl binary system and water+gas+Na Cl ternary systems.The cation/anion-water interaction parameters of are obtained by fitting the experimental data of ACI,mean ionic activity coefficients(MIAC)and liquid densities of water+Na Cl binary system.The cation/anion-gas interaction parameters are obtained by fitting the experimental data of gas solubilities in aqueous Na Cl solutions.The modeling results show that this new model can correlate well with the phase equilibrium and volumetric properties.Without gas,predictions for ACI,MIAC,and liquid densities present relative average deviations of 1.3%,3.6%and 1.4%compared to experimental reference values.For most gas-containing systems,predictions for gas solubilities present relative average deviations lower than 7.0%.Further,the contributions of ACI,and salting effects of Na Cl on gases are analyzed and discussed.
基金the National Natural Science Foundation of China(51273041)
文摘Physical properties including refractive index, density, viscosity and conductivity for binary mixtures of l-butyl- 3-methyl imidazolium chloride （[BMIM]CI） and different organic solvents at 298.15 K have been investigated. Ex- cess molar volumes have been calculated and obtained data has been fitted by the Redlich-Kister equation. The density and refractive index were found to increase with increasing concentration of [BMIM]CI, however, excep- tions do exist as in the case of dimethyl sulfoxide （DMSO）/[BMIM]CI. For DMSO/[BMIM]CI, the density decreases with increasing concentration. The addition of different organic solvents was able to disrupt the interactions within mixtures, leading to free mobility of ions. The free mobility of ions has been found to enhance conductivity and decrease viscosity to varying extents in all mixtures studied. It has been observed that solubility parameters, dielectric constants and composition of the solvents used play a vital role in determining the resultant properties. The data obtained will play an important role in understanding the effect of the addition of organic solvents in ILs to enhance their applicability.
基金Supported by Sultan Qaboos University,Petroleum and Chemical Engineering Department,Muscat Oman
文摘The conventional Rackett model for predicting liquid molar volume has been modified to cater for the effect of molar composition of the Deep Eutectic Solvents(DES). The experimental molar volume data for a group of commonly used DES has been used for optimizing the improved model. The data involved different molar compositions of each DES. The validation of the new model was performed on another set of DESs. The average relative deviation of the model on the training and validation datasets was approximately 0.1% while the Rackett model gave a relative deviation of more than 1.6%. The modified model deals with variations in DES molar composition and temperature in a more consistent way than the original Rackett model which exhibits monotonic performance degradation as temperature moves away from reference conditions. Having the composition of the DES as a model variable enhances the practical utilization of the predicting model in diverse design and process simulation applications.
基金supported by the National Natural Science Foundation of China (Nos. 41176063 and 41221004)the National Marine Public Welfare Research Project of China (No. 201205031)
文摘Chemotaxonomy based on diagnostic pigments is now a routine tool for macroscopic determination of the composition and abundance of phytoplankton in various aquatic environments. Since the taxonomic capability of this method depends on the relationships between diagnostic pigments and chlorophyll a of classified groups, it is critical to calibrate it by using pigment relationships obtained from representative and/or dominant species local to targeted investigation area. In this study, pigment profiles of 31 harmful algal bloom(HAB) species isolated from the coastal sea areas of China were analyzed with high performance liquid chromatography(HPLC). Pigment compositions, cellular pigment densities and ratios of pigments to chlorophyll a were determined and calculated. Among all these species, 25 kinds of pigments were detected, of which fucoxanthin, peridinin, 19'-butanoyloxyfucoxanthin, 19'-hexanoyloxyfucoxanthin, violaxanthin, and antheraxanthin were diagnostic pigments. Cellular pigment density was basically independent of species and environmental conditions, and therefore was recommended as a bridge to compare the results of HPLC-CHEMTAX technique with the traditional microscopy method. Pigment ratios of algal species isolated from the coast of China, especially the diagnostic pigment ratios, were higher than those from other locations. According to these results, pigment ratio ranges of four classes of phytoplankton common off the coast of China were summarized for using in the current chemotaxonomic method. Moreover, the differences of pigments ratios among different species under the same culturing conditions were consistent with their biological differences. Such differences have the potential to be used to classify the phytoplankton below class, which is meaningful for monitoring HABs by HPLC-CHEMTAX.
文摘The mathematical equations of 2-D thermal density flow in a channel were developed and a finite layer numerical model was established. In the direction of y, a cubic spline approximations were used for u and θ, and linear interpolation were used for du/dx and dθ/dx. The integration of differential equations along the direction of y was made with the subdomain scheme of weighted residual method. In the direction of x, the boundary value problem of differential equations was converted into an initial value problem. It is then solved by shooting method. An effective method for choosing and amending shooting multipoint initial values have been presented. The vertical distribution of u and θ at each x-section were also obtained.
基金supported by the National Natural Science Foundation of China(Grant Nos.51322101,51231004 and 51571128)the Ministry of Science and Technology of China(Grant No.2014AA032904)
文摘Manipulation of antiferromagnetic(AFM) spins by electrical means is on great demand to develop the AFM spintronics with low power consumption. Here we report a reversible electrical control of antiferromagnetic moments of FeMn up to 15 nm, using an ionic liquid to exert a substantial electric-field effect. The manipulation is demonstrated by the modulation of exchange spring in[Co/Pt]/FeMn system, where AFM moments in FeMn pin the magnetization rotation of Co/Pt. By carrier injection or extraction,the magnetic anisotropy of the top layer in FeMn is modulated to influence the whole exchange spring and then passes its influence to the [Co/Pt]/FeMn interface, through a distance up to the length of exchange spring that fully screens electric field. Comparing FeMn to IrMn, despite the opposite dependence of exchange bias on gate voltages, the same correlation between carrier density and exchange spring stiffness is demonstrated. Besides the fundamental significance of modulating the spin structures in metallic AFM via all-electrical fashion, the present finding would advance the development of low-power-consumption AFM spintronics.
