Fe2＋ oxidation by Acidithiobacillus ferrooxidans（At.ferrooxidans） under different solid contents by adding inert Al2O3 powder was examined in rotating-drum and stirred-tank reactors.The results show that the bioact...Fe2＋ oxidation by Acidithiobacillus ferrooxidans（At.ferrooxidans） under different solid contents by adding inert Al2O3 powder was examined in rotating-drum and stirred-tank reactors.The results show that the bioactivity of At.ferrooxidans in the stirred-tank is higher than that in the rotating-drum in the absence of Al2O3 powder,but the biooxidation rate of Fe2＋ decreases markedly from 0.23 g/（L·h） to 0.025 g/（L·h） with increasing the content of Al2O3 powder from 0 to 50%（mass fraction） in the stirred-tank probably due to the deactivation of At.ferrooxidans resulting from the collision and friction of solid particles.The increase in Al2O3 content has a little adverse effect on the bioactivity of At.ferrooxidans in the rotating-drum due to different mixing mechanisms of the two reactors.The biooxidation rate of Fe2＋ in the rotating-drum is higher than that in the stirred-tank at the same content of Al2O3 powder,especially at high solid content.The higher bioactivity of At.ferrooxidans can be maintained for allowing high solid content in the rotating-drum reactor,but its application potential still needs to be verified further by the sulfide bioleaching for the property differences of Al2O3 powder and sulfide minerals.展开更多
AA5083 friction stir welds were produced using systematic experimental design, the process forces and heat input with varying parameters were studied. Helpful empirical models were developed in designing friction stir...AA5083 friction stir welds were produced using systematic experimental design, the process forces and heat input with varying parameters were studied. Helpful empirical models were developed in designing friction stir welding （FSW） tools and FSW welders. These models may be further helpful for making process parameter choice for this sort of alloy, defining welding program and control of process parameters by using computer numerical control friction stir welding welders. The results show that tool rotational speed, welding speed and tool shoulder diameter are most significant parameters affecting axial force and heat input, while longitudinal force is significantly affected by welding speed and probe diameter.展开更多
The spatial structure of the velocity field in a stirred vessel with water has been measured and analyzed using the laser Doppler velocimeter technique, with the immersing depth and agitation speed of the impeller re-...The spatial structure of the velocity field in a stirred vessel with water has been measured and analyzed using the laser Doppler velocimeter technique, with the immersing depth and agitation speed of the impeller re-maining approximately constant. The experimental results were provided such as the mean velocity field, fluctuat-ing velocities, turbulent kinetic energy, Reynolds shear stress and time series of the velocity in the stirred tank. These results probably provided the valuable basis to further optimize and enlarge the stirred tank in the industrial process.展开更多
The influence of R/v ratio on joint quality in 2024-T351 aluminum alloy was studied. Specimens were subjected to friction stir welding with the rotation rates of 750, 950 and 1180 r/min and welding speed between 73 an...The influence of R/v ratio on joint quality in 2024-T351 aluminum alloy was studied. Specimens were subjected to friction stir welding with the rotation rates of 750, 950 and 1180 r/min and welding speed between 73 and 190 mm/min, providing R/v ratio between 5.00 and 10.27. The welded joints were tested by means of both non-destructive （visual, penetrant and X-ray inspection） and destructive （metallographic, tension and hardness） testing. In all specimens typical zones are revealed, with corresponding differences in grain size. Tensile efficiency of the joints obtained is in the range of 52.2%to 82.3%. The results show that the best quality is obtained at R/v ratio of 8.06, 10.17 and 10.27. This behavior is attributed to the assumption that the material flows around the pin with an optimal speed, i.e. sufficient amount of material is available to fill the gap and prevent tunnel formation. R/v ratio also showed influence on hardness distribution, onion features and crack initiation/propagation zones.展开更多
This work aims to provide a relationship of how the key operational variables of frother type and impeller speed affect the size of bubble （D32）. The study was performed using pilot-scale equipment （0.8 m^3） that ...This work aims to provide a relationship of how the key operational variables of frother type and impeller speed affect the size of bubble （D32）. The study was performed using pilot-scale equipment （0.8 m^3） that is up to two orders of magnitude larger than equipment used for studies performed to date by others, and incorporated the key process variables of frother type and impeller speed. The results show that each frother family exhibits a unique CCC95-HLB relationship dependent on n （number of C-atoms in alkyl group） and m （number of propylene oxide group）. Empirical models were developed to predict CCC95 from HLB associated with other two parameters a and ft. The impeller speed-bubble size tests show that D32 is unaffected by increased impeller tip speed across the range of 4.6 to 9.2 m/s （representing the industrial operating range）, although D32 starts to increase below 4.6 m/s. The finding is valid for both coalescing and non-coalescing conditions. The results suggest that the bubble size and bubble size distribution （BSD） being created do not change with increasing impeller speed in the quiescent zone of the flotation.展开更多
A non-specific symptom of one or more physical, or psychological processes in which screaming, shouting, complaining, moaning, cursing, pacing, fidgeting or wandering pose risk or discomfort, become disruptive or unsa...A non-specific symptom of one or more physical, or psychological processes in which screaming, shouting, complaining, moaning, cursing, pacing, fidgeting or wandering pose risk or discomfort, become disruptive or unsafe or interfere with the delivery of care are called agitation. Individuals in agitation manifest their condition through ＂pain behavior＂, which includes facial expressions. Clinicians regard the patient＇s facial expression as a valid indicator for pain and pain intensity. Hence, correct interpretation of the facial agitation of the patient and its correlation with pain is a fundamental step in designing an automated pain assessment system. Computer vision techniques can be used to quantify agitation in sedated patients in Intensive Care Unit （ICU）. In particular, such techniques can be used to develop objective agitation measurements from patient motion. In the case of paraplegic patients, whole body movement is not available, and hence, monitoring the whole body motion is not a viable solution. Hence in this case, the author measured head motion and facial grimacing for quantifying facial patient agitation in critical care based on Fuzzy k-NN.展开更多
The detection and identification of gross errors, especially measurement bias, plays a vital role in data reconciliation for nonlinear dynamic systems. Although parameter estimation method has been proved to be a pow-...The detection and identification of gross errors, especially measurement bias, plays a vital role in data reconciliation for nonlinear dynamic systems. Although parameter estimation method has been proved to be a pow-erful tool for bias identification, without a reliable and efficient bias detection strategy, the method is limited in ef-ficiency and cannot be applied widely. In this paper, a new bias detection strategy is constructed to detect the pres-ence of measurement bias and its occurrence time. With the help of this strategy, the number of parameters to be es-timated is greatly reduced, and sequential detections and iterations are also avoided. In addition, the number of de-cision variables of the optimization model is reduced, through which the influence of the parameters estimated is reduced. By incorporating the strategy into the parameter estimation model, a new methodology named IPEBD (Improved Parameter Estimation method with Bias Detection strategy) is constructed. Simulation studies on a con-tinuous stirred tank reactor (CSTR) and the Tennessee Eastman (TE) problem show that IPEBD is efficient for eliminating random errors, measurement biases and outliers contained in dynamic process data.展开更多
In this paper, particle image velocimetry (PIV) was used to measure the mean and root meansquare(RMS) velocity in the stirred tank with six-flat blade Rushton turbine and with no baffles. Two typesof motion patterns w...In this paper, particle image velocimetry (PIV) was used to measure the mean and root meansquare(RMS) velocity in the stirred tank with six-flat blade Rushton turbine and with no baffles. Two typesof motion patterns were studied. One was that the impeller runs at constant speed, the other was that the impellerruns at time-dependent speed and in a periodic way. The emphasis of the paper was on the comparison of meanand RMS velocity vector maps and profiles between these two types of motion patterns, and especial attention waspaid to the comparison of the mean velocity, time-averaged RMS velocity, phase averaged RMS velocity betweenthe constant 3 RPS (revolution per second) and time-dependent operation. The Reynolds number was between 763and 1527. The study explained the mechanism that time-dependent RPS is more efficient for mixing than that ofconstant RPS.展开更多
Oil-water separation is critical to solvent extraction process of rare earth, which can directly affect the yield and quality of the product. The experiments measure the two-phase separation time in a beaker, mixing u...Oil-water separation is critical to solvent extraction process of rare earth, which can directly affect the yield and quality of the product. The experiments measure the two-phase separation time in a beaker, mixing uniformity of two phases in the mixer and the oil phase entrainment at oil exit by the Karl Fischer method and numerical simulation for the mixersettler to study the combined effect of gravity and stirring. Experimental results show that relative to the static situation, the separation efficiency resulted from low-speed stirring is increased by 25%. The water content in the oil is a minimum at an offset distance L of 10 cm and the clearance off the tank bottom z of 10 cm is as low as 0.49%. Distribution images of oilwater separation at 2 s indicates that stirring is very conducive to the separation of the oil-water phase.展开更多
A silicone oil emulsion with 60% of solid content was prepared with methyl silicone oil used as the main material by means of the emulsifier-in-oil method.The influence of emulsification conditions on the droplet diam...A silicone oil emulsion with 60% of solid content was prepared with methyl silicone oil used as the main material by means of the emulsifier-in-oil method.The influence of emulsification conditions on the droplet diameter of silicone oil emulsion was discussed.The experimental results showed that the emulsification method,including the quantity of the emulsifier,the time and temperature of emulsification,the emulsifying water dosage,and the stirring speed,had significant impact on the droplet size.The optimal conditions were identified to achieve a smallest droplet diameter of the emulsion at an emulsifier dosage of 6%,an emulsification temperature of 70 ℃,an emulsification time of 30 min,and a stirring speed of 1100 r/min,with water added in two portions at a ratio of 1:1.The high-solid content silicone oil emulsion with a mean droplet diameter of 2.731 μm was prepared under these conditions that could ensure absence of stratification and floating oil under centrifuging at a speed of 3000 r/min for 30 min.展开更多
The bending moment acting on the overhung shaft of a gas-sparged vessel stirred by a Rushton turbine,as one of the results of fluid and structure interactions in stirred vessels,was measured using a moment sensor equi...The bending moment acting on the overhung shaft of a gas-sparged vessel stirred by a Rushton turbine,as one of the results of fluid and structure interactions in stirred vessels,was measured using a moment sensor equipped with digital telemetry.An analysis of the shaft bending moment amplitude shows that the amplitude distribution of the bending moment,which indicates the elasticity nature of shaft material against bending deformation,follows the Weibull distribution.The trends of amplitude mean,standard deviation and peak deviation characteristics manifest an "S" shape versus gas flow.The "S" trend of the relative mean bending moment over gas flow rate,depending on the flow regime in gas-liquid stirred vessels,resulted from the competition among the nonuniformity of bubbly flow around the impeller,the formation of gas cavities behind the blades,and the gas direct impact on the impeller when gas is introduced.A further analysis of the bending moment power spectral density shows that the rather low frequency and speed frequency are evident.The low-frequency contribution to bending moment fluctuation peaks in the complete dispersion regime.展开更多
The performance of data-driven models relies heavily on the amount and quality of training samples, so it might deteriorate significantly in the regions where samples are scarce. The objective of this paper is to deve...The performance of data-driven models relies heavily on the amount and quality of training samples, so it might deteriorate significantly in the regions where samples are scarce. The objective of this paper is to develop an online SVR model updating strategy to track the change in the process characteristics efficiently with affordable computational burden. This is achieved by adding a new sample that violates the Karush–Kuhn–Tucker conditions of the existing SVR model and by deleting the old sample that has the maximum distance with respect to the newly added sample in feature space. The benefits offered by such an updating strategy are exploited to develop an adaptive model-based control scheme, where model updating and control task perform alternately.The effectiveness of the adaptive controller is demonstrated by simulation study on a continuous stirred tank reactor. The results reveal that the adaptive MPC scheme outperforms its non-adaptive counterpart for largemagnitude set point changes and variations in process parameters.展开更多
基金Project(2010CB630904) supported by the National Basic Research Program of ChinaProject(5102030) supported by the Beijing Natural Science Foundation,China+1 种基金Projects(21076214,21006108) supported by the National Natural Science Foundation of ChinaProject supported by the Open Funding Project of the State Key Laboratory of Bioreactor Engineering,China
文摘Fe2＋ oxidation by Acidithiobacillus ferrooxidans（At.ferrooxidans） under different solid contents by adding inert Al2O3 powder was examined in rotating-drum and stirred-tank reactors.The results show that the bioactivity of At.ferrooxidans in the stirred-tank is higher than that in the rotating-drum in the absence of Al2O3 powder,but the biooxidation rate of Fe2＋ decreases markedly from 0.23 g/（L·h） to 0.025 g/（L·h） with increasing the content of Al2O3 powder from 0 to 50%（mass fraction） in the stirred-tank probably due to the deactivation of At.ferrooxidans resulting from the collision and friction of solid particles.The increase in Al2O3 content has a little adverse effect on the bioactivity of At.ferrooxidans in the rotating-drum due to different mixing mechanisms of the two reactors.The biooxidation rate of Fe2＋ in the rotating-drum is higher than that in the stirred-tank at the same content of Al2O3 powder,especially at high solid content.The higher bioactivity of At.ferrooxidans can be maintained for allowing high solid content in the rotating-drum reactor,but its application potential still needs to be verified further by the sulfide bioleaching for the property differences of Al2O3 powder and sulfide minerals.
文摘AA5083 friction stir welds were produced using systematic experimental design, the process forces and heat input with varying parameters were studied. Helpful empirical models were developed in designing friction stir welding （FSW） tools and FSW welders. These models may be further helpful for making process parameter choice for this sort of alloy, defining welding program and control of process parameters by using computer numerical control friction stir welding welders. The results show that tool rotational speed, welding speed and tool shoulder diameter are most significant parameters affecting axial force and heat input, while longitudinal force is significantly affected by welding speed and probe diameter.
基金Supported by the Natural Science Foundation of Inner Mongolia (No.200408020715).
文摘The spatial structure of the velocity field in a stirred vessel with water has been measured and analyzed using the laser Doppler velocimeter technique, with the immersing depth and agitation speed of the impeller re-maining approximately constant. The experimental results were provided such as the mean velocity field, fluctuat-ing velocities, turbulent kinetic energy, Reynolds shear stress and time series of the velocity in the stirred tank. These results probably provided the valuable basis to further optimize and enlarge the stirred tank in the industrial process.
基金Ministry of Education and Science of Serbia for financial support through Project TR34018
文摘The influence of R/v ratio on joint quality in 2024-T351 aluminum alloy was studied. Specimens were subjected to friction stir welding with the rotation rates of 750, 950 and 1180 r/min and welding speed between 73 and 190 mm/min, providing R/v ratio between 5.00 and 10.27. The welded joints were tested by means of both non-destructive （visual, penetrant and X-ray inspection） and destructive （metallographic, tension and hardness） testing. In all specimens typical zones are revealed, with corresponding differences in grain size. Tensile efficiency of the joints obtained is in the range of 52.2%to 82.3%. The results show that the best quality is obtained at R/v ratio of 8.06, 10.17 and 10.27. This behavior is attributed to the assumption that the material flows around the pin with an optimal speed, i.e. sufficient amount of material is available to fill the gap and prevent tunnel formation. R/v ratio also showed influence on hardness distribution, onion features and crack initiation/propagation zones.
基金Project supported by the Collaborative Research and Development Program of NSERC(Natural Sciences and Engineering Research Council of Canada) with Industrial Sponsorship from Vale,Teck Cominco,Xstrata Process Support,Agnico-Eagle,Shell Canada,Barrick Gold,COREM,SGS Lakefield Research and Flottec
文摘This work aims to provide a relationship of how the key operational variables of frother type and impeller speed affect the size of bubble （D32）. The study was performed using pilot-scale equipment （0.8 m^3） that is up to two orders of magnitude larger than equipment used for studies performed to date by others, and incorporated the key process variables of frother type and impeller speed. The results show that each frother family exhibits a unique CCC95-HLB relationship dependent on n （number of C-atoms in alkyl group） and m （number of propylene oxide group）. Empirical models were developed to predict CCC95 from HLB associated with other two parameters a and ft. The impeller speed-bubble size tests show that D32 is unaffected by increased impeller tip speed across the range of 4.6 to 9.2 m/s （representing the industrial operating range）, although D32 starts to increase below 4.6 m/s. The finding is valid for both coalescing and non-coalescing conditions. The results suggest that the bubble size and bubble size distribution （BSD） being created do not change with increasing impeller speed in the quiescent zone of the flotation.
文摘A non-specific symptom of one or more physical, or psychological processes in which screaming, shouting, complaining, moaning, cursing, pacing, fidgeting or wandering pose risk or discomfort, become disruptive or unsafe or interfere with the delivery of care are called agitation. Individuals in agitation manifest their condition through ＂pain behavior＂, which includes facial expressions. Clinicians regard the patient＇s facial expression as a valid indicator for pain and pain intensity. Hence, correct interpretation of the facial agitation of the patient and its correlation with pain is a fundamental step in designing an automated pain assessment system. Computer vision techniques can be used to quantify agitation in sedated patients in Intensive Care Unit （ICU）. In particular, such techniques can be used to develop objective agitation measurements from patient motion. In the case of paraplegic patients, whole body movement is not available, and hence, monitoring the whole body motion is not a viable solution. Hence in this case, the author measured head motion and facial grimacing for quantifying facial patient agitation in critical care based on Fuzzy k-NN.
基金Supported by the National High Technology Research and Development Program of China (2006AA04Z176)
文摘The detection and identification of gross errors, especially measurement bias, plays a vital role in data reconciliation for nonlinear dynamic systems. Although parameter estimation method has been proved to be a pow-erful tool for bias identification, without a reliable and efficient bias detection strategy, the method is limited in ef-ficiency and cannot be applied widely. In this paper, a new bias detection strategy is constructed to detect the pres-ence of measurement bias and its occurrence time. With the help of this strategy, the number of parameters to be es-timated is greatly reduced, and sequential detections and iterations are also avoided. In addition, the number of de-cision variables of the optimization model is reduced, through which the influence of the parameters estimated is reduced. By incorporating the strategy into the parameter estimation model, a new methodology named IPEBD (Improved Parameter Estimation method with Bias Detection strategy) is constructed. Simulation studies on a con-tinuous stirred tank reactor (CSTR) and the Tennessee Eastman (TE) problem show that IPEBD is efficient for eliminating random errors, measurement biases and outliers contained in dynamic process data.
文摘In this paper, particle image velocimetry (PIV) was used to measure the mean and root meansquare(RMS) velocity in the stirred tank with six-flat blade Rushton turbine and with no baffles. Two typesof motion patterns were studied. One was that the impeller runs at constant speed, the other was that the impellerruns at time-dependent speed and in a periodic way. The emphasis of the paper was on the comparison of meanand RMS velocity vector maps and profiles between these two types of motion patterns, and especial attention waspaid to the comparison of the mean velocity, time-averaged RMS velocity, phase averaged RMS velocity betweenthe constant 3 RPS (revolution per second) and time-dependent operation. The Reynolds number was between 763and 1527. The study explained the mechanism that time-dependent RPS is more efficient for mixing than that ofconstant RPS.
基金financially supported by the National 863 Plan (2010AA03A405, and 2012AA062303)the National 973 Plan (2012CBA01205)+2 种基金the National Natural Science Foundation of China (U1202274, 51204040)the National Science and Technology Support Program (2012BAE01B02)Fundamental Research Funds for the Central Universities (N130702001 and N130607001)
文摘Oil-water separation is critical to solvent extraction process of rare earth, which can directly affect the yield and quality of the product. The experiments measure the two-phase separation time in a beaker, mixing uniformity of two phases in the mixer and the oil phase entrainment at oil exit by the Karl Fischer method and numerical simulation for the mixersettler to study the combined effect of gravity and stirring. Experimental results show that relative to the static situation, the separation efficiency resulted from low-speed stirring is increased by 25%. The water content in the oil is a minimum at an offset distance L of 10 cm and the clearance off the tank bottom z of 10 cm is as low as 0.49%. Distribution images of oilwater separation at 2 s indicates that stirring is very conducive to the separation of the oil-water phase.
文摘A silicone oil emulsion with 60% of solid content was prepared with methyl silicone oil used as the main material by means of the emulsifier-in-oil method.The influence of emulsification conditions on the droplet diameter of silicone oil emulsion was discussed.The experimental results showed that the emulsification method,including the quantity of the emulsifier,the time and temperature of emulsification,the emulsifying water dosage,and the stirring speed,had significant impact on the droplet size.The optimal conditions were identified to achieve a smallest droplet diameter of the emulsion at an emulsifier dosage of 6%,an emulsification temperature of 70 ℃,an emulsification time of 30 min,and a stirring speed of 1100 r/min,with water added in two portions at a ratio of 1:1.The high-solid content silicone oil emulsion with a mean droplet diameter of 2.731 μm was prepared under these conditions that could ensure absence of stratification and floating oil under centrifuging at a speed of 3000 r/min for 30 min.
文摘The bending moment acting on the overhung shaft of a gas-sparged vessel stirred by a Rushton turbine,as one of the results of fluid and structure interactions in stirred vessels,was measured using a moment sensor equipped with digital telemetry.An analysis of the shaft bending moment amplitude shows that the amplitude distribution of the bending moment,which indicates the elasticity nature of shaft material against bending deformation,follows the Weibull distribution.The trends of amplitude mean,standard deviation and peak deviation characteristics manifest an "S" shape versus gas flow.The "S" trend of the relative mean bending moment over gas flow rate,depending on the flow regime in gas-liquid stirred vessels,resulted from the competition among the nonuniformity of bubbly flow around the impeller,the formation of gas cavities behind the blades,and the gas direct impact on the impeller when gas is introduced.A further analysis of the bending moment power spectral density shows that the rather low frequency and speed frequency are evident.The low-frequency contribution to bending moment fluctuation peaks in the complete dispersion regime.
基金Supported by the National Basic Research Program of China(2012CB720500)Postdoctoral Science Foundation of China(2013M541964)Fundamental Research Funds for the Central Universities(13CX05021A)
文摘The performance of data-driven models relies heavily on the amount and quality of training samples, so it might deteriorate significantly in the regions where samples are scarce. The objective of this paper is to develop an online SVR model updating strategy to track the change in the process characteristics efficiently with affordable computational burden. This is achieved by adding a new sample that violates the Karush–Kuhn–Tucker conditions of the existing SVR model and by deleting the old sample that has the maximum distance with respect to the newly added sample in feature space. The benefits offered by such an updating strategy are exploited to develop an adaptive model-based control scheme, where model updating and control task perform alternately.The effectiveness of the adaptive controller is demonstrated by simulation study on a continuous stirred tank reactor. The results reveal that the adaptive MPC scheme outperforms its non-adaptive counterpart for largemagnitude set point changes and variations in process parameters.
