An optical emission spectroscopy(OES)method with a non-invasive measurement capability,without inducing disturbance to the discharge,represents an effective method for material monitoring.However,when the OES method i...An optical emission spectroscopy(OES)method with a non-invasive measurement capability,without inducing disturbance to the discharge,represents an effective method for material monitoring.However,when the OES method is employed to monitor the trace erosion product within the ceramic channel of a Hall thruster,it becomes challenging to distinguish between signal and noise.In this study,we propose a model filtering method based on the signal characteristics of the Hall thruster plume spectrometer.This method integrates the slit imaging and spectral resolution features of the spectrometer.Employing this method,we extract the spectral signals of the erosion product and working gas from the Hall thruster under different operating conditions.The results indicate that our new method performs comparably to the traditional method without model filtering when extracting atom signals from strong xenon working gas.However,for trace amounts of the erosion product,our approach significantly enhances the signal-to-noise ratio(SNR),enabling the identification of extremely weak spectral signals even under low mass flow rate and low-voltage conditions.We obtain boron atom concentration of 3.91×10^(-3) kg/m^(3) at a mass flow rate of 4×10^(-7) kg/s and voltage of 200 V while monitoring a wider range of thruster operating conditions.The new method proposed in this study is suitable for monitoring other low-concentration elements,making it valuable for materials processing,environmental monitoring and space propulsion applications.展开更多
To characterize the mean and variance of stochastic concentration distributions in heterogeneous porous media,we derived conservation equations using the first-order perturbation approach and assuming stationary fluct...To characterize the mean and variance of stochastic concentration distributions in heterogeneous porous media,we derived conservation equations using the first-order perturbation approach and assuming stationary fluctuation fields of velocity and concentration.The concentration variance equation,similar to the mean concentration equation,consists of convection and dispersion terms with the mean water velocity and macrodispersivity.In addition,there is a production term in the concentration variance e-quation.The concentration variance production is quadratically proportional to the mean concentration gradient with a coefficient Qij,defined as the concentration variance productivity,which is the difference between the macrodispersivity Aij and the local dispersivity aij multiplied by a four-rank tensor.The macrodispersivity and the local dispersivity,respectively,result in the creation and dissipation of the concentration variance.The concentration variance is produced if the concentration gradient exists.For t→∞,Qij→0,which indicates that the creation and dissipation of the concentration variance are balanced at large travel time.We solve the variance equation numerically along with the mean e-quation using Aij,Qij,and the effective solute velocity v.The variance productivity increases with the decrease in transverse local dispersivity and is not sensitive to longitudinal local dispersivity.The maximum concentration variance occurs near the maximum mean concentration gradient.展开更多
The establishment of biosafety system is of enormous importance to the livestock and poultry production in terms of mitigating the transmission of diseases and implementing regional prevention and control measures.How...The establishment of biosafety system is of enormous importance to the livestock and poultry production in terms of mitigating the transmission of diseases and implementing regional prevention and control measures.However,the current sterilization technology presents several drawbacks,including time-consuming procedures,chemical residues,and challenges in treating the sewage after rinsing.In this study,a novel cleaning and sterilization method that combines slightly acidic electrolyzed water and high pressure water-jet was developed.An orthogonal test was conducted to examine the correlation between high-pressure conditions and the various non-structural parameters on the efficacy of sterilization rate.In a field test,the effectiveness of the technology in cleaning pig transfer vehicles was evaluated by the total plate count and variations of community composition.The findings revealed that the combination of process parameters,including an available chlorine concentration of 200 mg/L,rinsing pressure of 170 bar,rinsing duration of 10 s,and residence time of 15 min,resulted in a removal rate of colony concentration on the surface of pig transfer vehicles of(96.50±0.91)%.Moreover,it was demonstrated to effectively inhibit a variety of pathogenic bacteria.The innovative cleaning system has the potential to replace traditional methods and reduces pollution while saving time and labor.It introduces a novel approach for sterilization of transportation in livestock and poultry farms as well as the biosafety construction of the animal husbandry.展开更多
基金financially supported by National Natural Science Foundation of China(No.U22B2094)。
文摘An optical emission spectroscopy(OES)method with a non-invasive measurement capability,without inducing disturbance to the discharge,represents an effective method for material monitoring.However,when the OES method is employed to monitor the trace erosion product within the ceramic channel of a Hall thruster,it becomes challenging to distinguish between signal and noise.In this study,we propose a model filtering method based on the signal characteristics of the Hall thruster plume spectrometer.This method integrates the slit imaging and spectral resolution features of the spectrometer.Employing this method,we extract the spectral signals of the erosion product and working gas from the Hall thruster under different operating conditions.The results indicate that our new method performs comparably to the traditional method without model filtering when extracting atom signals from strong xenon working gas.However,for trace amounts of the erosion product,our approach significantly enhances the signal-to-noise ratio(SNR),enabling the identification of extremely weak spectral signals even under low mass flow rate and low-voltage conditions.We obtain boron atom concentration of 3.91×10^(-3) kg/m^(3) at a mass flow rate of 4×10^(-7) kg/s and voltage of 200 V while monitoring a wider range of thruster operating conditions.The new method proposed in this study is suitable for monitoring other low-concentration elements,making it valuable for materials processing,environmental monitoring and space propulsion applications.
基金funded by NNSF of China and NSF-EPSCoR of University of Wyoming,USA.
文摘To characterize the mean and variance of stochastic concentration distributions in heterogeneous porous media,we derived conservation equations using the first-order perturbation approach and assuming stationary fluctuation fields of velocity and concentration.The concentration variance equation,similar to the mean concentration equation,consists of convection and dispersion terms with the mean water velocity and macrodispersivity.In addition,there is a production term in the concentration variance e-quation.The concentration variance production is quadratically proportional to the mean concentration gradient with a coefficient Qij,defined as the concentration variance productivity,which is the difference between the macrodispersivity Aij and the local dispersivity aij multiplied by a four-rank tensor.The macrodispersivity and the local dispersivity,respectively,result in the creation and dissipation of the concentration variance.The concentration variance is produced if the concentration gradient exists.For t→∞,Qij→0,which indicates that the creation and dissipation of the concentration variance are balanced at large travel time.We solve the variance equation numerically along with the mean e-quation using Aij,Qij,and the effective solute velocity v.The variance productivity increases with the decrease in transverse local dispersivity and is not sensitive to longitudinal local dispersivity.The maximum concentration variance occurs near the maximum mean concentration gradient.
基金support of this project by the Strategic Priority Research Program of the National Center of Technology Innovation for Pigs(Grant No.NCTIP-XD/B07).
文摘The establishment of biosafety system is of enormous importance to the livestock and poultry production in terms of mitigating the transmission of diseases and implementing regional prevention and control measures.However,the current sterilization technology presents several drawbacks,including time-consuming procedures,chemical residues,and challenges in treating the sewage after rinsing.In this study,a novel cleaning and sterilization method that combines slightly acidic electrolyzed water and high pressure water-jet was developed.An orthogonal test was conducted to examine the correlation between high-pressure conditions and the various non-structural parameters on the efficacy of sterilization rate.In a field test,the effectiveness of the technology in cleaning pig transfer vehicles was evaluated by the total plate count and variations of community composition.The findings revealed that the combination of process parameters,including an available chlorine concentration of 200 mg/L,rinsing pressure of 170 bar,rinsing duration of 10 s,and residence time of 15 min,resulted in a removal rate of colony concentration on the surface of pig transfer vehicles of(96.50±0.91)%.Moreover,it was demonstrated to effectively inhibit a variety of pathogenic bacteria.The innovative cleaning system has the potential to replace traditional methods and reduces pollution while saving time and labor.It introduces a novel approach for sterilization of transportation in livestock and poultry farms as well as the biosafety construction of the animal husbandry.
