Research results of prediction of urban construction land scale were sum- marized from the aspects of influencing factors of construction land expansion and prediction models of construction land scale, and their char...Research results of prediction of urban construction land scale were sum- marized from the aspects of influencing factors of construction land expansion and prediction models of construction land scale, and their characteristics and deficiencies of these studies were analyzed to provide reference for deep research on pre- diction of urban construction land scale in China. The results show that there are few studies on basic theories about total scale of construction land presently, and there is no theoretical framework in studies on influencing factors. A single model has been used to conduct prediction on a small scale in most studies, but there have been few studies on iarge-scale prediction based on comprehensive benefit. Therefore, it is necessary to strengthen the exploration of basic theory and mechanism of urban construction land prediction, study iarge-scale prediction based on comprehensive benefit, and strengthen the comprehensive application of econometric analysis, spatial analysis and information technology analysis.展开更多
Based on the two-dimensional (2D) system theory, an integrated predictive iterative learning control (2D-IPILC) strategy for batch processes is presented. First, the output response and the error transition model ...Based on the two-dimensional (2D) system theory, an integrated predictive iterative learning control (2D-IPILC) strategy for batch processes is presented. First, the output response and the error transition model predictions along the batch index can be calculated analytically due to the 2D Roesser model of the batch process. Then, an integrated framework of combining iterative learning control (ILC) and model predictive control (MPC) is formed reasonably. The output of feedforward ILC is estimated on the basis of the predefined process 2D model. By min- imizing a quadratic objective function, the feedback MPC is introduced to obtain better control performance for tracking problem of batch processes. Simulations on a typical batch reactor demonstrate that the satisfactory tracking performance as well as faster convergence speed can be achieved than traditional proportion type (P- t-we) ILC despite the model error and disturbances.展开更多
Soft-sensing is widely used in industrial applications. The traditional soft-sensing structure is open-loop without correction mechanism. If the working condition is changed or there is unknown disturbance, the foreca...Soft-sensing is widely used in industrial applications. The traditional soft-sensing structure is open-loop without correction mechanism. If the working condition is changed or there is unknown disturbance, the forecast result of soft-sensing model may be incorrect. In order to obtain accurate values, it is necessary to carry out online correction. In this paper, a semiclosed-loop framework (SLF) is proposed to establish a soft-sensing approach, which estimates the input variables in the next moment by a prediction model and calibrates the output variables by a compensation model. The experimental results show that the proposed method has better prediction accuracy and robustness than other open-loop models.展开更多
This paper investigates the scaled prediction variances in the errors-in-variables model and compares the performance with those in classic model of response surface designs for three factors.The ordinary least square...This paper investigates the scaled prediction variances in the errors-in-variables model and compares the performance with those in classic model of response surface designs for three factors.The ordinary least squares estimators of regression coefficients are derived from a second-order response surface model with errors in variables.Three performance criteria are proposed.The first is the difference between the empirical mean of maximum value of scaled prediction variance with errors and the maximum value of scaled prediction variance without errors.The second is the mean squared deviation from the mean of simulated maximum scaled prediction variance with errors.The last performance measure is the mean squared scaled prediction variance change with and without errors.In the simulations,1 000 random samples were performed following three factors with 20 experimental runs for central composite designs and 15 for Box-Behnken design.The independent variables are coded variables in these designs.Comparative results show that for the low level errors in variables,central composite face-centered design is optimal;otherwise,Box-Behnken design has a relatively better performance.展开更多
Several parameter identification methods of thermal response test were evaluated through numerical and experimental study.A three-dimensional finite-volume numerical model was established under the assumption that the...Several parameter identification methods of thermal response test were evaluated through numerical and experimental study.A three-dimensional finite-volume numerical model was established under the assumption that the soil thermal conductivity had been known in the simulation of thermal response test.The thermal response curve was firstly obtained through numerical calculation.Then,the accuracy of the numerical model was verified with measured data obtained through a thermal response test.Based on the numerical and experimental thermal response curves,the thermal conductivity of the soil was calculated by different parameter identification methods.The calculated results were compared with the assumed value and then the accuracy of these methods was evaluated.Furthermore,the effects of test time,variable data quality,borehole radius,initial ground temperature,and heat injection rate were analyzed.The results show that the method based on cylinder-source model has a low precision and the identified thermal conductivity decreases with an increase in borehole radius.For parameter estimation,the measuring accuracy of the initial temperature of the deep ground soil has greater effect on identified thermal conductivity.展开更多
L-(+)-lactic acid production was studied by immobilized Lactobacillus rhamnosus T1STR108 on crude pectin from Krung Kha Mao Leaves. Central composite design was employed to determine the maximum lactic acid product...L-(+)-lactic acid production was studied by immobilized Lactobacillus rhamnosus T1STR108 on crude pectin from Krung Kha Mao Leaves. Central composite design was employed to determine the maximum lactic acid production of 42.88 g L-1 in predicted model with the factors at 4.11 g L1 of pectin, 6.05 mLLl inoculum and 1.09 mm of bead diameter. Statistical analyses demonstrated very high significance for the regression model, since the F-value computed 116.09 was much higher than the tabulated F-value 2.08 for the lactic acid production at 5% level for linear and quadratic polynomial regression models. The highest experimental lactic acid production was 43.57 g L^-1 at 96 h of fermentation, 1.58% higher than the predicted value.展开更多
Based on radon gas properties and its existing projects applications, we firstly attempted to apply geo- physical and chemical properties of radon gas in the field of mining engineering, and imported radioac- tive mea...Based on radon gas properties and its existing projects applications, we firstly attempted to apply geo- physical and chemical properties of radon gas in the field of mining engineering, and imported radioac- tive measurement method to detect the development process of the overlying strata mining-induced fractures and their contained water quality in underground coal mining, which not only innovates a more simple-fast-reliable detection method, but also further expands the applications of radon gas detection technology in mining field. A 3D simulation design of comprehensive testing system for detecting strata mining-induced fractures on surface with radon gas (CTSR) was carried out by using a large-scale 3D solid model design software Pro/Engineer (Pro/E), which overcame three main disadvantages of ''static design thought, 2D planar design and heavy workload for remodification design'' on exiting design for mining engineering test systems. Meanwhile, based on the simulation design results of Pro/E software, the sta- bility of the jack-screw pressure bar for the key component in CTSR was checked with a material mechan- ics theory, which provided a reliable basis for materials selection during the latter machining process.展开更多
In this paper, a concept for the joint modeling of the device load and user intention is presented. It consists of two coupled models, a device load model to characterize the power consumption of an electric device of...In this paper, a concept for the joint modeling of the device load and user intention is presented. It consists of two coupled models, a device load model to characterize the power consumption of an electric device of interest, and a user intention model for describing the user intentions which cause the energy consumption. The advantage of this joint model is the ability to predict the device load from the user intention and to reconstruct the user intention from the measured device load. This opens a new way for load monitoring, simulation and prediction from the perspective of users instead of devices.展开更多
This paper extends a prediction model for multi-directional random wave transformation based on an energy balance equation by Mase with the consideration of wave shoaling, refraction, diffraction, reflection and break...This paper extends a prediction model for multi-directional random wave transformation based on an energy balance equation by Mase with the consideration of wave shoaling, refraction, diffraction, reflection and breaking. This numerical model is improved by 1) introducing Wen's frequency spectrum and Mitsuyasu's directional function, which are more suitable to the coastal area of China; 2) considering energy dissipation caused by bottom friction, which ensures more accurate results for large-scale and shallow water areas; 3) taking into account a non-linear dispersion relation. Predictions using the extended wave model are carried out to study the feasibility of constructing the Ai Hua yacht port in Qingdao, China, with a comparison between two port layouts in design. Wave fields inside the port for different incident wave directions, water levels and return periods are simulated, and then two kinds of parameters are calculated to evaluate the wave conditions for the two layouts. Analyses show that Layout I is better than Layout II. Calculation results also show that the harbor will be calm for different wave directions under the design water level. On the contrary, the wave conditions do not wholly meet the requirements of a yacht port for ship berthing under the extreme water level. For safety consideration, the elevation of the breakwater might need to be properly increased to prevent wave overtopping under such water level. The extended numerical simulation model may provide an effective approach to computing wave heights in a harbor.展开更多
An optical readout uncooled infrared (IR) imaging detector of bimaterial cantilever array using knife-edge filter operation (KEFO) is demonstrated. The angle change of each cantilever in a focal plane array (FPA...An optical readout uncooled infrared (IR) imaging detector of bimaterial cantilever array using knife-edge filter operation (KEFO) is demonstrated. The angle change of each cantilever in a focal plane array (FPA) can be simultaneously detected with a resolution of 10.5 degree. A deformation magnifying substrate-free micro-cantilever unit with multi-fold interval metaUized legs is specially designed and modeled. A FPA with 160×160 pixels is fabricated and thermal images with noise equivalent temperature difference (NETD) of 400 mK are obtained by this imaging detector.展开更多
An expansion procedure to design partially decentralized controllers via model predictive control is proposed in this paper. Partially decentralized control is a control structure that lies between a fully decentraliz...An expansion procedure to design partially decentralized controllers via model predictive control is proposed in this paper. Partially decentralized control is a control structure that lies between a fully decentralized structure and a fully centralized one, and has the advantage of achieving comparable performance as a fully centralized controller but with simpler structure. The proposed method follows the expansion method proposed in a previous paper where internal model control (IMC) was used to design controllers for non-square subsystems. The method requires computing the pseudo-inverse of a non-square matrix via pseudo-inverse factors. Instead, the proposed method uses dynamic matrix control (DMC) to design PID controllers for non-square subsystems without using additional factors. The effectiveness of the proposed method is demonstrated on several chemical examples. Simulation results show that the proposed method is simple and can achieve better performance.展开更多
In ultrasonic extraction technology, optimization of technical parameters often considers extraction medium only, without including ultrasonic parameters. This paper focuses on controlling the ultrasonic extraction pr...In ultrasonic extraction technology, optimization of technical parameters often considers extraction medium only, without including ultrasonic parameters. This paper focuses on controlling the ultrasonic extraction process of puerarin, investigating the influence of ultrasonic parameters on extraction rate, and empirically analyzing the main components of Pueraria, i.e., isoflavone compounds. A method is presented combining orthogonal experi- mental design with a support vector machine and a predictive model is established for optimization of technical parameters. From the analysis with the predictive model, appropriate process parameters are achieved for higher extraction rate. With these parameters in the ultrasonic extraction of puerarin, the experimental result is satisfactory. This method is of significance to the study of extracfing root-stock plant medicines.展开更多
A continuous-time nonlinear model predictive controller(NMPC) was designed for a boiler-turbine unit.The controller was designed by optimizing a receding-horizon performance index,with the nonlinear system approximate...A continuous-time nonlinear model predictive controller(NMPC) was designed for a boiler-turbine unit.The controller was designed by optimizing a receding-horizon performance index,with the nonlinear system approximated by its Taylor series expansion with a certain order,the magnitude saturation constraints on the inputs satisfied by increasing the predictive time,and the rate saturation conditions on the actuators satisfied by tuning the time constant of the reference trajectories in a reference governor.Simulation results showed that the controller can drive the drum pressure and output power of the nonlinear boiler-turbine unit to follow their respective reference trajectories throughout a varying operation range and keep the water level deviation within tolerances.Comparison of the NMPC scheme with the generic model control(GMC) scheme indicated that the responses are slower and there are more oscillations in the responses of the water level,fuel flow input and feed water flow input in the GMC scheme when the boiler-turbine unit is operating over a wide range.展开更多
The application of knowledge is a primary source of growth in the knowledge economy. The World Bank Group has developed a rigorous assessment methodology for assessing a country's ability to access and use knowledge ...The application of knowledge is a primary source of growth in the knowledge economy. The World Bank Group has developed a rigorous assessment methodology for assessing a country's ability to access and use knowledge to become more competitive in the knowledge economy of the 21st century. The World Bank's annual knowledge economy index is grounded on a four-pillar model: (1) economic incentives and institutional regime; (2) education and skills; (3) information and communication infrastructure; and (4) innovation systems. An argument can be made that the model lacks coverage of some key factors that pertain to intellectual capital and the production and consumption of knowledge. The model's heavy focus on economic incentives and open institutional regimes comes at a societal cost. This paper proposes an alternative knowledge economy index which is grounded in a more holistic and balanced view of a knowledge society. Adopting the perspective of triple bottom line shifts the purpose and design of a knowledge economy from one of aggregation and reporting to action and involvement. The World Bank's scorecard and indexing methodology are adaptable to this new perspective and a new set of indicators.展开更多
This paper falls into two parts. In the first part, the widely used analytical-empirical method of pavement design and evaluation is discussed and in the second part two simulation models are presented to predict the ...This paper falls into two parts. In the first part, the widely used analytical-empirical method of pavement design and evaluation is discussed and in the second part two simulation models are presented to predict the design of flexible pavement. Analytical results are compared with simulation models.展开更多
To optimize the design and improve the performance of wastewater treatment bioreactors,the review concerning the hydrodynamics explored by theoretical equations,process experiments,modeling of the hydrodynamics and fl...To optimize the design and improve the performance of wastewater treatment bioreactors,the review concerning the hydrodynamics explored by theoretical equations,process experiments,modeling of the hydrodynamics and flow field measurement is presented. Results of different kinds of experiments show that the hydrodynamic characteristics can affect sludge characteristics,mass transfer and reactor performance significantly. Along with the development of theoretical equations,turbulence models including large eddy simulation models and Reynolds-averaged Navier-Stokes (RANS) models are widely used at present. Standard and modified k-ε models are the most widely used eddy viscosity turbulence models for simulating flows in bioreactors. Numerical simulation of hydrodynamics is proved to be efficient for optimizing design and operation. The development of measurement techniques with high accuracy and low intrusion enables the flow filed in the bioreactors to be transparent. Integration of both numerical simulation and experimental measurement can describe the hydrodynamics very well.展开更多
A new model without any fitting parameter for estimating the mean liquid recirculating velocity has been derived from previous work directly. The prediction agrees with experimental data reasonably well. Accurency of ...A new model without any fitting parameter for estimating the mean liquid recirculating velocity has been derived from previous work directly. The prediction agrees with experimental data reasonably well. Accurency of prediction from the new model is comparable with the models reported in the literature. However, the new model has a potential capability to predict the average liquid recirculation velocity at elevated pressure bubble columns since n and c is developed under pressure. However this needs to be further tested experimentally.展开更多
In this paper, several mechanical deformation curves of limestone are reviewed, and the effects of temperature, confining pressure, and fluid are discussed. Generally, Mohr–Coulomb is used for limestone brittle fract...In this paper, several mechanical deformation curves of limestone are reviewed, and the effects of temperature, confining pressure, and fluid are discussed. Generally, Mohr–Coulomb is used for limestone brittle fracture. The characteristic of low temperature cataclastic flow and the conditions and constitutive equations of intracrystal plastic deformation such as dislocation creep,diffusion creep, and superplastic flow are discussed in detail. Specifically, from the macroscopic and microscopic view, inelastic compression deformation(shear-enhanced compaction) of large porosity limestone is elaborated.Compared with other mechanics models and strength equations, the dual porosity(macroporosity and microporosity) model is superior and more consistent with experimental data. Previous research has suffered from a shortage of high temperature and high pressure limestone research; we propose several suggestions to avoid this problem in the future:(1) fluid-rock interaction research;(2) mutual transition between natural conditions and laboratory research;(3) the uniform strength criterion forshear-enhanced compaction deformation;(4) test equipment; and(5) superplastic flow mechanism research.展开更多
文摘Research results of prediction of urban construction land scale were sum- marized from the aspects of influencing factors of construction land expansion and prediction models of construction land scale, and their characteristics and deficiencies of these studies were analyzed to provide reference for deep research on pre- diction of urban construction land scale in China. The results show that there are few studies on basic theories about total scale of construction land presently, and there is no theoretical framework in studies on influencing factors. A single model has been used to conduct prediction on a small scale in most studies, but there have been few studies on iarge-scale prediction based on comprehensive benefit. Therefore, it is necessary to strengthen the exploration of basic theory and mechanism of urban construction land prediction, study iarge-scale prediction based on comprehensive benefit, and strengthen the comprehensive application of econometric analysis, spatial analysis and information technology analysis.
基金Supported in part by the State Key Development Program for Basic Research of China(2012CB720505)the National Natural Science Foundation of China(61174105,60874049)
文摘Based on the two-dimensional (2D) system theory, an integrated predictive iterative learning control (2D-IPILC) strategy for batch processes is presented. First, the output response and the error transition model predictions along the batch index can be calculated analytically due to the 2D Roesser model of the batch process. Then, an integrated framework of combining iterative learning control (ILC) and model predictive control (MPC) is formed reasonably. The output of feedforward ILC is estimated on the basis of the predefined process 2D model. By min- imizing a quadratic objective function, the feedback MPC is introduced to obtain better control performance for tracking problem of batch processes. Simulations on a typical batch reactor demonstrate that the satisfactory tracking performance as well as faster convergence speed can be achieved than traditional proportion type (P- t-we) ILC despite the model error and disturbances.
基金Supported by the National Natural Science Foundation of China (60934007, 61074060, 61104078)the Research and Innovation Project of Shanghai Education Commission (11CXY08)the State Key Laboratory of Synthetical Automation forProcess Industries
文摘Soft-sensing is widely used in industrial applications. The traditional soft-sensing structure is open-loop without correction mechanism. If the working condition is changed or there is unknown disturbance, the forecast result of soft-sensing model may be incorrect. In order to obtain accurate values, it is necessary to carry out online correction. In this paper, a semiclosed-loop framework (SLF) is proposed to establish a soft-sensing approach, which estimates the input variables in the next moment by a prediction model and calibrates the output variables by a compensation model. The experimental results show that the proposed method has better prediction accuracy and robustness than other open-loop models.
基金Supported by National Natural Science Foundation of China (No.70871087 and No.70931004)
文摘This paper investigates the scaled prediction variances in the errors-in-variables model and compares the performance with those in classic model of response surface designs for three factors.The ordinary least squares estimators of regression coefficients are derived from a second-order response surface model with errors in variables.Three performance criteria are proposed.The first is the difference between the empirical mean of maximum value of scaled prediction variance with errors and the maximum value of scaled prediction variance without errors.The second is the mean squared deviation from the mean of simulated maximum scaled prediction variance with errors.The last performance measure is the mean squared scaled prediction variance change with and without errors.In the simulations,1 000 random samples were performed following three factors with 20 experimental runs for central composite designs and 15 for Box-Behnken design.The independent variables are coded variables in these designs.Comparative results show that for the low level errors in variables,central composite face-centered design is optimal;otherwise,Box-Behnken design has a relatively better performance.
基金Project(xjj20100078) supported by the Fundamental Research Funds for the Central Universities in China
文摘Several parameter identification methods of thermal response test were evaluated through numerical and experimental study.A three-dimensional finite-volume numerical model was established under the assumption that the soil thermal conductivity had been known in the simulation of thermal response test.The thermal response curve was firstly obtained through numerical calculation.Then,the accuracy of the numerical model was verified with measured data obtained through a thermal response test.Based on the numerical and experimental thermal response curves,the thermal conductivity of the soil was calculated by different parameter identification methods.The calculated results were compared with the assumed value and then the accuracy of these methods was evaluated.Furthermore,the effects of test time,variable data quality,borehole radius,initial ground temperature,and heat injection rate were analyzed.The results show that the method based on cylinder-source model has a low precision and the identified thermal conductivity decreases with an increase in borehole radius.For parameter estimation,the measuring accuracy of the initial temperature of the deep ground soil has greater effect on identified thermal conductivity.
文摘L-(+)-lactic acid production was studied by immobilized Lactobacillus rhamnosus T1STR108 on crude pectin from Krung Kha Mao Leaves. Central composite design was employed to determine the maximum lactic acid production of 42.88 g L-1 in predicted model with the factors at 4.11 g L1 of pectin, 6.05 mLLl inoculum and 1.09 mm of bead diameter. Statistical analyses demonstrated very high significance for the regression model, since the F-value computed 116.09 was much higher than the tabulated F-value 2.08 for the lactic acid production at 5% level for linear and quadratic polynomial regression models. The highest experimental lactic acid production was 43.57 g L^-1 at 96 h of fermentation, 1.58% higher than the predicted value.
基金support for this work provided by the Fundamental Research Funds for the Central Universities(China University of Mining & Technology) (No. 2010ZDP02B02)the State Key Laboratory of Coal Resources and Safe Mining(No. SKLCRSM08X02)
文摘Based on radon gas properties and its existing projects applications, we firstly attempted to apply geo- physical and chemical properties of radon gas in the field of mining engineering, and imported radioac- tive measurement method to detect the development process of the overlying strata mining-induced fractures and their contained water quality in underground coal mining, which not only innovates a more simple-fast-reliable detection method, but also further expands the applications of radon gas detection technology in mining field. A 3D simulation design of comprehensive testing system for detecting strata mining-induced fractures on surface with radon gas (CTSR) was carried out by using a large-scale 3D solid model design software Pro/Engineer (Pro/E), which overcame three main disadvantages of ''static design thought, 2D planar design and heavy workload for remodification design'' on exiting design for mining engineering test systems. Meanwhile, based on the simulation design results of Pro/E software, the sta- bility of the jack-screw pressure bar for the key component in CTSR was checked with a material mechan- ics theory, which provided a reliable basis for materials selection during the latter machining process.
文摘In this paper, a concept for the joint modeling of the device load and user intention is presented. It consists of two coupled models, a device load model to characterize the power consumption of an electric device of interest, and a user intention model for describing the user intentions which cause the energy consumption. The advantage of this joint model is the ability to predict the device load from the user intention and to reconstruct the user intention from the measured device load. This opens a new way for load monitoring, simulation and prediction from the perspective of users instead of devices.
基金supported by the National Natural Science Foundation of China (50879085)the Program for New Century Excellent Talents in University(NCET-07-0778)Fundamental Research Funds for the Central Universities (2012QNA4020)
文摘This paper extends a prediction model for multi-directional random wave transformation based on an energy balance equation by Mase with the consideration of wave shoaling, refraction, diffraction, reflection and breaking. This numerical model is improved by 1) introducing Wen's frequency spectrum and Mitsuyasu's directional function, which are more suitable to the coastal area of China; 2) considering energy dissipation caused by bottom friction, which ensures more accurate results for large-scale and shallow water areas; 3) taking into account a non-linear dispersion relation. Predictions using the extended wave model are carried out to study the feasibility of constructing the Ai Hua yacht port in Qingdao, China, with a comparison between two port layouts in design. Wave fields inside the port for different incident wave directions, water levels and return periods are simulated, and then two kinds of parameters are calculated to evaluate the wave conditions for the two layouts. Analyses show that Layout I is better than Layout II. Calculation results also show that the harbor will be calm for different wave directions under the design water level. On the contrary, the wave conditions do not wholly meet the requirements of a yacht port for ship berthing under the extreme water level. For safety consideration, the elevation of the breakwater might need to be properly increased to prevent wave overtopping under such water level. The extended numerical simulation model may provide an effective approach to computing wave heights in a harbor.
基金This work is supported by National Natural Science Foundationof China (Grant No. 10232030,50076040,10472111)NationalBasic Research Program of China (2006CB300404).
文摘An optical readout uncooled infrared (IR) imaging detector of bimaterial cantilever array using knife-edge filter operation (KEFO) is demonstrated. The angle change of each cantilever in a focal plane array (FPA) can be simultaneously detected with a resolution of 10.5 degree. A deformation magnifying substrate-free micro-cantilever unit with multi-fold interval metaUized legs is specially designed and modeled. A FPA with 160×160 pixels is fabricated and thermal images with noise equivalent temperature difference (NETD) of 400 mK are obtained by this imaging detector.
基金Supported by the National Natural Science Foundation of China (61174096)the Natural Science Foundation of Beijing(4122075)the Natural Science Foundation of Hebei Province (F2011502069)
文摘An expansion procedure to design partially decentralized controllers via model predictive control is proposed in this paper. Partially decentralized control is a control structure that lies between a fully decentralized structure and a fully centralized one, and has the advantage of achieving comparable performance as a fully centralized controller but with simpler structure. The proposed method follows the expansion method proposed in a previous paper where internal model control (IMC) was used to design controllers for non-square subsystems. The method requires computing the pseudo-inverse of a non-square matrix via pseudo-inverse factors. Instead, the proposed method uses dynamic matrix control (DMC) to design PID controllers for non-square subsystems without using additional factors. The effectiveness of the proposed method is demonstrated on several chemical examples. Simulation results show that the proposed method is simple and can achieve better performance.
基金Supported by the National Natural Science Foundation of China(21146009,21376014)
文摘In ultrasonic extraction technology, optimization of technical parameters often considers extraction medium only, without including ultrasonic parameters. This paper focuses on controlling the ultrasonic extraction process of puerarin, investigating the influence of ultrasonic parameters on extraction rate, and empirically analyzing the main components of Pueraria, i.e., isoflavone compounds. A method is presented combining orthogonal experi- mental design with a support vector machine and a predictive model is established for optimization of technical parameters. From the analysis with the predictive model, appropriate process parameters are achieved for higher extraction rate. With these parameters in the ultrasonic extraction of puerarin, the experimental result is satisfactory. This method is of significance to the study of extracfing root-stock plant medicines.
基金the Natural Science Foundation of China (No.50636010)
文摘A continuous-time nonlinear model predictive controller(NMPC) was designed for a boiler-turbine unit.The controller was designed by optimizing a receding-horizon performance index,with the nonlinear system approximated by its Taylor series expansion with a certain order,the magnitude saturation constraints on the inputs satisfied by increasing the predictive time,and the rate saturation conditions on the actuators satisfied by tuning the time constant of the reference trajectories in a reference governor.Simulation results showed that the controller can drive the drum pressure and output power of the nonlinear boiler-turbine unit to follow their respective reference trajectories throughout a varying operation range and keep the water level deviation within tolerances.Comparison of the NMPC scheme with the generic model control(GMC) scheme indicated that the responses are slower and there are more oscillations in the responses of the water level,fuel flow input and feed water flow input in the GMC scheme when the boiler-turbine unit is operating over a wide range.
文摘The application of knowledge is a primary source of growth in the knowledge economy. The World Bank Group has developed a rigorous assessment methodology for assessing a country's ability to access and use knowledge to become more competitive in the knowledge economy of the 21st century. The World Bank's annual knowledge economy index is grounded on a four-pillar model: (1) economic incentives and institutional regime; (2) education and skills; (3) information and communication infrastructure; and (4) innovation systems. An argument can be made that the model lacks coverage of some key factors that pertain to intellectual capital and the production and consumption of knowledge. The model's heavy focus on economic incentives and open institutional regimes comes at a societal cost. This paper proposes an alternative knowledge economy index which is grounded in a more holistic and balanced view of a knowledge society. Adopting the perspective of triple bottom line shifts the purpose and design of a knowledge economy from one of aggregation and reporting to action and involvement. The World Bank's scorecard and indexing methodology are adaptable to this new perspective and a new set of indicators.
文摘This paper falls into two parts. In the first part, the widely used analytical-empirical method of pavement design and evaluation is discussed and in the second part two simulation models are presented to predict the design of flexible pavement. Analytical results are compared with simulation models.
基金Sponsored by the National Basic Research Program of China( 973 Program)(Grant No.G2000026402)
文摘To optimize the design and improve the performance of wastewater treatment bioreactors,the review concerning the hydrodynamics explored by theoretical equations,process experiments,modeling of the hydrodynamics and flow field measurement is presented. Results of different kinds of experiments show that the hydrodynamic characteristics can affect sludge characteristics,mass transfer and reactor performance significantly. Along with the development of theoretical equations,turbulence models including large eddy simulation models and Reynolds-averaged Navier-Stokes (RANS) models are widely used at present. Standard and modified k-ε models are the most widely used eddy viscosity turbulence models for simulating flows in bioreactors. Numerical simulation of hydrodynamics is proved to be efficient for optimizing design and operation. The development of measurement techniques with high accuracy and low intrusion enables the flow filed in the bioreactors to be transparent. Integration of both numerical simulation and experimental measurement can describe the hydrodynamics very well.
文摘A new model without any fitting parameter for estimating the mean liquid recirculating velocity has been derived from previous work directly. The prediction agrees with experimental data reasonably well. Accurency of prediction from the new model is comparable with the models reported in the literature. However, the new model has a potential capability to predict the average liquid recirculation velocity at elevated pressure bubble columns since n and c is developed under pressure. However this needs to be further tested experimentally.
基金supported by Strategic Priority Research Program (B) of the Chinese Academy of Sciences under Grant XDB18010401135 Program of the Institute of Geochemistry, Chinese Academy of Sciences
文摘In this paper, several mechanical deformation curves of limestone are reviewed, and the effects of temperature, confining pressure, and fluid are discussed. Generally, Mohr–Coulomb is used for limestone brittle fracture. The characteristic of low temperature cataclastic flow and the conditions and constitutive equations of intracrystal plastic deformation such as dislocation creep,diffusion creep, and superplastic flow are discussed in detail. Specifically, from the macroscopic and microscopic view, inelastic compression deformation(shear-enhanced compaction) of large porosity limestone is elaborated.Compared with other mechanics models and strength equations, the dual porosity(macroporosity and microporosity) model is superior and more consistent with experimental data. Previous research has suffered from a shortage of high temperature and high pressure limestone research; we propose several suggestions to avoid this problem in the future:(1) fluid-rock interaction research;(2) mutual transition between natural conditions and laboratory research;(3) the uniform strength criterion forshear-enhanced compaction deformation;(4) test equipment; and(5) superplastic flow mechanism research.