Occasional irregular initial solidification phenomena,including stickers,deep oscillation marks,depressions,and surface cracks of strand shells in continuous casting molds,are important limitations for developing the ...Occasional irregular initial solidification phenomena,including stickers,deep oscillation marks,depressions,and surface cracks of strand shells in continuous casting molds,are important limitations for developing the high-efficiency continuous casting of steels.The application of mold thermal monitoring(MTM) systems,which use thermocouples to detect and respond to temperature variations in molds,has become an effective method to address irregular initial solidification phenomena.Such systems are widely applied in numerous steel companies for sticker breakout prediction.However,monitoring the surface defects of strands remains immature.Hence,indepth research is necessary to utilize the potential advantages and comprehensive monitoring of MTM systems.This paper summarizes what is included in the irregular initial solidification phenomena and systematically reviews the current state of research on these phenomena by the MTM systems.Furthermore,the influences of mold slag behavior on monitoring these phenomena are analyzed.Finally,the remaining problems of the formation mechanisms and investigations of irregular initial solidification phenomena are discussed,and future research directions are proposed.展开更多
This paper studies the parameter estimation problems of the nonlinear systems described by the bilinear state space models in the presence of disturbances.A bilinear state observer is designed for deriving identificat...This paper studies the parameter estimation problems of the nonlinear systems described by the bilinear state space models in the presence of disturbances.A bilinear state observer is designed for deriving identification algorithms to estimate the state variables using the input-output data.Based on the bilinear state observer,a novel gradient iterative algorithm is derived for estimating the parameters of the bilinear systems by means of the continuous mixed p-norm cost function.The gain at each iterative step adapts to the data quality so that the algorithm has good robustness to the noise disturbance.Furthermore,to improve the performance of the proposed algorithm,a dynamicmoving window is designed which can update the dynamical data by removing the oldest data and adding the newestmeasurement data.A numerical example of identification of bilinear systems is presented to validate the theoretical analysis.展开更多
Based on the social influence theory,the influence of virtual brand community members’perceived value on social influencing factors is discussed,and the influence of social influencing factors on virtual brand commun...Based on the social influence theory,the influence of virtual brand community members’perceived value on social influencing factors is discussed,and the influence of social influencing factors on virtual brand community members’continuous participation in decision-making is analyzed.Through an empirical analysis of the survey data of Xiaomi users in the Xiaomi Community,the results showed that the perceived value of virtual brand community members significantly and positively affects social influencing factors,which also significantly and positively affect the members’continuous participation in virtual brand communities.Therefore,only by sharing valuable information resources and improving the efficiency of information flow,thereby enhancing the perceived value of the community and increasing the stickiness of members to the virtual community,will we have an opportunity to enhance the interaction among members and effectively promote continuous participation in community activities through the strong bonds formed among members.展开更多
This article deals with the problem of minimizing ruin probability under optimal control for the continuous-time compound binomial model with investment. The jump mechanism in our article is different from that of Liu...This article deals with the problem of minimizing ruin probability under optimal control for the continuous-time compound binomial model with investment. The jump mechanism in our article is different from that of Liu et al [4]. Comparing with [4], the introduction of the investment, and hence, the additional Brownian motion term, makes the problem technically challenging. To overcome this technical difficulty, the theory of change of measure is used and an exponential martingale is obtained by virtue of the extended generator. The ruin probability is minimized through maximizing adjustment coefficient in the sense of Lundberg bounds. At the same time, the optimal investment strategy is obtained.展开更多
A three-dimensional heat transfer model for continuous steel slab casting has been developed with realistic spray cooling patterns and a coupled microsegregation solidification model that calculates the solidification...A three-dimensional heat transfer model for continuous steel slab casting has been developed with realistic spray cooling patterns and a coupled microsegregation solidification model that calculates the solidification path for multi-component steels. Temperature and composition dependent properties are implemented in a database for 15 chemical species. Considerable effort is made to accurately model the spray cooling heat transfer. Each spray nozzle position and distribution is considered, including variations of the spray patterns with flow rate, and spray overlap. Nozzle type, layout, nozzle-to-slab distance, and spray span and flux are variable. Natural convection, thermal radiation and contact cooling of individual rolls are computed. The present model provides more comprehensive information and realistic slab surface temperatures than results from a model using the 'averaged' treatment of boundary conditions. Cooling operating conditions and parameters of individual spray nozzles can be analyzed to optimize nozzle spray distribution, improve product quality, and troubleshoot issues such as nozzle clogging that may arise during production. One spray cooling correlation is used for the entire machine, achieving as good or better agreement with surface temperature measurements than was found previously for the model using an 'averaged' treatment of boundary conditions and using three machine-segment-dependent correlations.展开更多
In view of the periodic bending deformation of solid-liquid interface in the solidification process for continuous casting slab, the variation of temperature gradient and dendritic spacing in the front edge of the sol...In view of the periodic bending deformation of solid-liquid interface in the solidification process for continuous casting slab, the variation of temperature gradient and dendritic spacing in the front edge of the solid-liquid interface, and the nucleation and propagation process of crack were studied. It is shown that the bending deformation of the interface results in the temperature field change in the front edge of solid-liquid interface, and the occurrence of temperature gradient along drawing direction results in the growth of secondary dendrites. The initial crack formed during the middle and final stage of solidification may extend to the surface of the casting slab and become an internal crack. The results of the theoretical analysis are basically in agreement with that of the experiment.展开更多
A new method called mixed Lagrangian and Eulerian （MiLE） method was used to simulate the continuous casting process in a mold of free-cutting steel 38MnVS.The simulation results are basically in agreement with exper...A new method called mixed Lagrangian and Eulerian （MiLE） method was used to simulate the continuous casting process in a mold of free-cutting steel 38MnVS.The simulation results are basically in agreement with experimental data in the literature,achieving the three-dimensional visualization of temperature distribution,melt flow,shell thickness,and stress distribution of blooms in a mold.It is shown that the flow velocity of steel melt becomes smaller gradually as the casting proceeds.When the flow reaches a certain depth,two types of flow patterns can be observed in the upper zone of the mold.The first flow pattern is to flow downwards,and the second one is to flow upwards to the meniscus.The corner temperature is higher,and the thickness is thinner than those in the mid-face.The effective stress in the corner area is much bigger than that in the mid-face,indicating that the corner area is the dangerous zone of cracking.展开更多
The increasing speed of trains necessitates the development of brake-disc materials that meet more stringent requirements.Therefore,Nb and V have been added to Cr–Mo–V steel to improve its thermal fatigue performanc...The increasing speed of trains necessitates the development of brake-disc materials that meet more stringent requirements.Therefore,Nb and V have been added to Cr–Mo–V steel to improve its thermal fatigue performance when used in brake discs.In this paper,the influences of Nb and V on the static continuous cooling transformation(CCT)behaviors of undercooled austenite were studied.The microstructures,hardness,and dislocation densities at different cooling rates and with the addition of different alloying elements were also investigated.The results show that the transformation products of ferrite,granular bainite,lower bainite,and martensite form under different cooling conditions.With increasing Nb and V contents,the CCT curves are shifted to the left,ferrite and bainite transformations are promoted,and the critical cooling rate of total martensite formation is increased.The added V mainly forms V-rich M_8C_7 precipitates and reduces the dissolved C content;therefore,the A_(c1),A_(c3),and M_s-point temperatures increase.Moreover,the stability of retained austenite is also reduced;its content therefore decreases.Compared with V,the effect of added Nb is weaker because of its smaller content.However,the addition of Nb improves the hardness at lower cooling rates because of the precipitation of fine Nb C particles and refining of the microstructure.展开更多
The 3-dimensional fluid flow in a water model of the continuous casting tundish is simulated with the k-ε two-equation turbulence model. The methods to decide the size of wall-adjacent grids and the effects of resid...The 3-dimensional fluid flow in a water model of the continuous casting tundish is simulated with the k-ε two-equation turbulence model. The methods to decide the size of wall-adjacent grids and the effects of residuals and mesh size on the simulation accuracy are discussed. The current investigation concludes that the following condition should be satisfied to get accurate enough simulation results: (1) If the dimension of the domain is in the order of cubic meters, the average size of cells in the mesh system should be at least smaller than 30 mm; (2) The normalized non-scaled residual should be reached at least smaller than 10-4.展开更多
This study tested an improved fiber tracking algorithm, which was based on fiber assignment using a continuous tracking algorithm and a two-tensor model. Different models and tracking decisions were used by judging th...This study tested an improved fiber tracking algorithm, which was based on fiber assignment using a continuous tracking algorithm and a two-tensor model. Different models and tracking decisions were used by judging the type of estimation of each voxel. Thismethod should solve the cross-track problem. This study included eight healthy subjects, two axonal injury patients and seven demyelinating disease patients. This new algorithm clearly exhibited a difference in nerve fiber direction between axonal injury and demyelinating disease patients and healthy control subjects. Compared with fiber assignment with a continuous tracking algorithm, our novel method can track more and longer nerve fibers, and also can solve the fiber crossing problem.展开更多
Spectroscopy can be used for detecting crop characteristics. A goal of crop spectrum analysis is to extract effective features from spectral data for establishing a detection model. An ideal spectral feature set shoul...Spectroscopy can be used for detecting crop characteristics. A goal of crop spectrum analysis is to extract effective features from spectral data for establishing a detection model. An ideal spectral feature set should have high sensitivity to target parameters but low information redundancy among features.However, feature-selection methods that satisfy both requirements are lacking. To address this issue,in this study, a novel method, the continuous wavelet projections algorithm(CWPA), was developed,which has advantages of both continuous wavelet analysis(CWA) and the successive projections algorithm(SPA) for generating optimal spectral feature set for crop detection. Three datasets collected for crop stress detection and retrieval of biochemical properties were used to validate the CWPA under both classification and regression scenarios. The CWPA generated a feature set with fewer features yet achieving accuracy comparable to or even higher than those of CWA and SPA. With only two to three features identified by CWPA, an overall accuracy of 98% in classifying tea plant stresses was achieved, and high coefficients of determination were obtained in retrieving corn leaf chlorophyll content(R^(2)= 0.8521)and equivalent water thickness(R^(2)= 0.9508). The mechanism of the CWPA ensures that the novel algorithm discovers the most sensitive features while retaining complementarity among features. Its ability to reduce the data dimension suggests its potential for crop monitoring and phenotyping with hyperspectral data.展开更多
A model of the continuous melt transesterification process of bisphenol-A and diphenyl carbonate in a continuous stirred tank reactor to produce polycarbonate is presented. The model is developed by using the molecula...A model of the continuous melt transesterification process of bisphenol-A and diphenyl carbonate in a continuous stirred tank reactor to produce polycarbonate is presented. The model is developed by using the molecular species model of polycarbonate melt polycondensation and the modeling method of reactive flash. Liquid phase is treated as perfect mixed flow and the vapor phase is assumed following the ideal gas law. With this model, the continuous melt transesterification process of bisphenol-A and diphenyl carbonate is examined with respect to different orocess parameters.展开更多
In this paper, we construct some continuous but non-differentiable functions defined by quinary dec-imal, that are Kiesswetter-like functions. We discuss their properties, then investigate the Hausdorff dimensions of ...In this paper, we construct some continuous but non-differentiable functions defined by quinary dec-imal, that are Kiesswetter-like functions. We discuss their properties, then investigate the Hausdorff dimensions of graphs of these functions and give a detailed proof.展开更多
BACKGROUND:The study aims to investigate an optimal indicator for changing the filter during the continuous renal replacement therapy(CRRT)in intensive care unit(ICU)patients with acute kidney injury(AKI).METHODS:Pati...BACKGROUND:The study aims to investigate an optimal indicator for changing the filter during the continuous renal replacement therapy(CRRT)in intensive care unit(ICU)patients with acute kidney injury(AKI).METHODS:Patients with AKI requiring CRRT in an ICU were randomly divided into two groups for crossover trial,i.e.,groups A and B.Patients in the group A were firstly treated with continuous veno-venous hemofiltration(CVVH),followed by continuous veno-venous hemodiafiltration(CVVHDF).Patients in the group B were firstly treated with CVVHDF followed by CVVH.Delivered doses of solutes with different molecular weights at the indicated time points between groups were compared.A correlation analysis between the delivered dose and pre-filter pressure(P_(PRE))and transmembrane pressure(P_(TM))was performed.Receiver operating characteristic(ROC)curves were constructed to evaluate the accuracy of P_(TM) as an indicator for filter replacement.RESULTS:A total of 50 cases were analyzed,27 in the group A and 23 in the group B.Delivered doses of different molecular-weight solutes significantly decreased before changing the filter in both modalities,compared with those at the initiation of treatment(all P<0.05).In the late stage of CRRT,the possible rebound of serum medium-molecular-weight solute concentration was observed.P_(TM) was negatively correlated with the delivered dose of medium-molecular-weight solute in both modalities.The threshold for predicting the rebound of serum concentration of medium-molecularweight solute by P_(TM) was 146.5 mm Hg(1 mm Hg=0.133 k Pa).CONCLUSIONS:The filter can be used as long as possible within the manufacturer’s safe use time limits to remove small-molecular-weight solutes.P_(TM) of 146.5 mm Hg may be an optimal indicator for changing the filter in CRRT therapies to remove medium-molecular-weight solutes.展开更多
In this paper,a common characteristic of real number system and well ordered set is revealed and proved to be an equivalent form of the Dedekind Axiom or the Continuous Induction in R. Basing on it,we get the unified ...In this paper,a common characteristic of real number system and well ordered set is revealed and proved to be an equivalent form of the Dedekind Axiom or the Continuous Induction in R. Basing on it,we get the unified form of the mathematical induction,the transfinite induction and the continuous induction and generalize induction to totally ordered set that has the same characteristic.展开更多
In this paper,a common characteristic of real number system and well ordered set is revealed and proved to be an equivalent form of the Dedekind Axiom or the Continuous Induction in R. Basing on it,we get the unif...In this paper,a common characteristic of real number system and well ordered set is revealed and proved to be an equivalent form of the Dedekind Axiom or the Continuous Induction in R. Basing on it,we get the unified form of the mathematical induction,the transfinite induction and the continuous induction and generalize induction to totally ordered set that has the same characteristic.展开更多
This paper reviews recent developments in the contin- uous processing of steels in Japan.The following items are discussed:continuous casting-direct rolling(CC-DR) process of hot-rolled strip:thermomechanical control ...This paper reviews recent developments in the contin- uous processing of steels in Japan.The following items are discussed:continuous casting-direct rolling(CC-DR) process of hot-rolled strip:thermomechanical control process(TMCP)of heavy plates:in—line heat treating pro- cess of rails:direct lead patenting(DLP)process of wire rods;and fully integrated processing line(FIPL)of cold-rolled strip.展开更多
Continuous casting of thin slabs is a key state project for 7th and sth five -year plans. On thebasis of foundamental works , CISRI condueted the tests of 102 heats in Lanzhou Steel Works in the periodof January 1991-...Continuous casting of thin slabs is a key state project for 7th and sth five -year plans. On thebasis of foundamental works , CISRI condueted the tests of 102 heats in Lanzhou Steel Works in the periodof January 1991- June 1992. Three slab assortments of 50× 900 mm . 70 × 900 mm , 70 × 500 mm were ex-amined. In June of 1992, 412 t steel of 46 heats were cast with the efficiency of 91. 3 %. This. result meetsthe requiremeni of the state in this period. The mould, hedt transfer . casting technology and factors influ-encing slab’s qualities are investigated as well.展开更多
The effect of molybdenum on the continuous cooling transformation behavior of the micro-alloyed low carbon steel containing niobium and titanium was investigated by a Gleeble 3800 thermo-mechanical simulator. The phas...The effect of molybdenum on the continuous cooling transformation behavior of the micro-alloyed low carbon steel containing niobium and titanium was investigated by a Gleeble 3800 thermo-mechanical simulator. The phase transformation temperature of the steel at various cooling rates was detected. The microstmcture was observed by optical microscope （OM） and scanning electronic microscope （ SEM）, and its Vickers hardness was tested. Based on these, its dynamic continuous cooling transformation （CCT） diagrams were determined. The results show that the transformation temperature from deformed austenite to acicular ferrite （AF） is decreased when Mo is added, and the formation of pro- eutectoid ferrite （F） and pearlite （P） is either inhabited or postponed. Mo can also enlarge the range of the cooling rate in forming AF, and refine the microstructure effectively.展开更多
We establish the existence and uniqueness of classical solutions of the continuous casting problem with surface tension and kinetic conditions in a short time interval.
基金supported by the National Natural Science Foundation of China(No.52274319)。
文摘Occasional irregular initial solidification phenomena,including stickers,deep oscillation marks,depressions,and surface cracks of strand shells in continuous casting molds,are important limitations for developing the high-efficiency continuous casting of steels.The application of mold thermal monitoring(MTM) systems,which use thermocouples to detect and respond to temperature variations in molds,has become an effective method to address irregular initial solidification phenomena.Such systems are widely applied in numerous steel companies for sticker breakout prediction.However,monitoring the surface defects of strands remains immature.Hence,indepth research is necessary to utilize the potential advantages and comprehensive monitoring of MTM systems.This paper summarizes what is included in the irregular initial solidification phenomena and systematically reviews the current state of research on these phenomena by the MTM systems.Furthermore,the influences of mold slag behavior on monitoring these phenomena are analyzed.Finally,the remaining problems of the formation mechanisms and investigations of irregular initial solidification phenomena are discussed,and future research directions are proposed.
基金funded by the National Natural Science Foundation of China(No.61773182)the 111 Project(B12018).
文摘This paper studies the parameter estimation problems of the nonlinear systems described by the bilinear state space models in the presence of disturbances.A bilinear state observer is designed for deriving identification algorithms to estimate the state variables using the input-output data.Based on the bilinear state observer,a novel gradient iterative algorithm is derived for estimating the parameters of the bilinear systems by means of the continuous mixed p-norm cost function.The gain at each iterative step adapts to the data quality so that the algorithm has good robustness to the noise disturbance.Furthermore,to improve the performance of the proposed algorithm,a dynamicmoving window is designed which can update the dynamical data by removing the oldest data and adding the newestmeasurement data.A numerical example of identification of bilinear systems is presented to validate the theoretical analysis.
文摘Based on the social influence theory,the influence of virtual brand community members’perceived value on social influencing factors is discussed,and the influence of social influencing factors on virtual brand community members’continuous participation in decision-making is analyzed.Through an empirical analysis of the survey data of Xiaomi users in the Xiaomi Community,the results showed that the perceived value of virtual brand community members significantly and positively affects social influencing factors,which also significantly and positively affect the members’continuous participation in virtual brand communities.Therefore,only by sharing valuable information resources and improving the efficiency of information flow,thereby enhancing the perceived value of the community and increasing the stickiness of members to the virtual community,will we have an opportunity to enhance the interaction among members and effectively promote continuous participation in community activities through the strong bonds formed among members.
基金supported by the Nature Science Foundation of Hebei Province(A2014202202)supported by the Nature Science Foundation of China(11471218)
文摘This article deals with the problem of minimizing ruin probability under optimal control for the continuous-time compound binomial model with investment. The jump mechanism in our article is different from that of Liu et al [4]. Comparing with [4], the introduction of the investment, and hence, the additional Brownian motion term, makes the problem technically challenging. To overcome this technical difficulty, the theory of change of measure is used and an exponential martingale is obtained by virtue of the extended generator. The ruin probability is minimized through maximizing adjustment coefficient in the sense of Lundberg bounds. At the same time, the optimal investment strategy is obtained.
基金The authors are grateful to IPSCO Inc. for supporting this research program and for providing surface temperature measure-ments, and measurements of the spray nozzle flow characteris-tics. Without the nozzle flow pattern measurements made by Dr. L.K.Chia
文摘A three-dimensional heat transfer model for continuous steel slab casting has been developed with realistic spray cooling patterns and a coupled microsegregation solidification model that calculates the solidification path for multi-component steels. Temperature and composition dependent properties are implemented in a database for 15 chemical species. Considerable effort is made to accurately model the spray cooling heat transfer. Each spray nozzle position and distribution is considered, including variations of the spray patterns with flow rate, and spray overlap. Nozzle type, layout, nozzle-to-slab distance, and spray span and flux are variable. Natural convection, thermal radiation and contact cooling of individual rolls are computed. The present model provides more comprehensive information and realistic slab surface temperatures than results from a model using the 'averaged' treatment of boundary conditions. Cooling operating conditions and parameters of individual spray nozzles can be analyzed to optimize nozzle spray distribution, improve product quality, and troubleshoot issues such as nozzle clogging that may arise during production. One spray cooling correlation is used for the entire machine, achieving as good or better agreement with surface temperature measurements than was found previously for the model using an 'averaged' treatment of boundary conditions and using three machine-segment-dependent correlations.
基金supported by the National Natural Science Foundation of China(No.50374043).
文摘In view of the periodic bending deformation of solid-liquid interface in the solidification process for continuous casting slab, the variation of temperature gradient and dendritic spacing in the front edge of the solid-liquid interface, and the nucleation and propagation process of crack were studied. It is shown that the bending deformation of the interface results in the temperature field change in the front edge of solid-liquid interface, and the occurrence of temperature gradient along drawing direction results in the growth of secondary dendrites. The initial crack formed during the middle and final stage of solidification may extend to the surface of the casting slab and become an internal crack. The results of the theoretical analysis are basically in agreement with that of the experiment.
基金supported by the National Natural Science Foundation of China (No.50874007)
文摘A new method called mixed Lagrangian and Eulerian （MiLE） method was used to simulate the continuous casting process in a mold of free-cutting steel 38MnVS.The simulation results are basically in agreement with experimental data in the literature,achieving the three-dimensional visualization of temperature distribution,melt flow,shell thickness,and stress distribution of blooms in a mold.It is shown that the flow velocity of steel melt becomes smaller gradually as the casting proceeds.When the flow reaches a certain depth,two types of flow patterns can be observed in the upper zone of the mold.The first flow pattern is to flow downwards,and the second one is to flow upwards to the meniscus.The corner temperature is higher,and the thickness is thinner than those in the mid-face.The effective stress in the corner area is much bigger than that in the mid-face,indicating that the corner area is the dangerous zone of cracking.
基金financially supported by the National Nature Science Foundation of China (Nos.51674020 and 51571019)the National Key Research and Development Program of China (No.2016YFB0300102-5)
文摘The increasing speed of trains necessitates the development of brake-disc materials that meet more stringent requirements.Therefore,Nb and V have been added to Cr–Mo–V steel to improve its thermal fatigue performance when used in brake discs.In this paper,the influences of Nb and V on the static continuous cooling transformation(CCT)behaviors of undercooled austenite were studied.The microstructures,hardness,and dislocation densities at different cooling rates and with the addition of different alloying elements were also investigated.The results show that the transformation products of ferrite,granular bainite,lower bainite,and martensite form under different cooling conditions.With increasing Nb and V contents,the CCT curves are shifted to the left,ferrite and bainite transformations are promoted,and the critical cooling rate of total martensite formation is increased.The added V mainly forms V-rich M_8C_7 precipitates and reduces the dissolved C content;therefore,the A_(c1),A_(c3),and M_s-point temperatures increase.Moreover,the stability of retained austenite is also reduced;its content therefore decreases.Compared with V,the effect of added Nb is weaker because of its smaller content.However,the addition of Nb improves the hardness at lower cooling rates because of the precipitation of fine Nb C particles and refining of the microstructure.
文摘The 3-dimensional fluid flow in a water model of the continuous casting tundish is simulated with the k-ε two-equation turbulence model. The methods to decide the size of wall-adjacent grids and the effects of residuals and mesh size on the simulation accuracy are discussed. The current investigation concludes that the following condition should be satisfied to get accurate enough simulation results: (1) If the dimension of the domain is in the order of cubic meters, the average size of cells in the mesh system should be at least smaller than 30 mm; (2) The normalized non-scaled residual should be reached at least smaller than 10-4.
基金supported by Xiamen Technology Projects Grand (The study of chronic cerebrovascular insufficiently in Magnetic Resonance Imaging), No.3502Z20084028
文摘This study tested an improved fiber tracking algorithm, which was based on fiber assignment using a continuous tracking algorithm and a two-tensor model. Different models and tracking decisions were used by judging the type of estimation of each voxel. Thismethod should solve the cross-track problem. This study included eight healthy subjects, two axonal injury patients and seven demyelinating disease patients. This new algorithm clearly exhibited a difference in nerve fiber direction between axonal injury and demyelinating disease patients and healthy control subjects. Compared with fiber assignment with a continuous tracking algorithm, our novel method can track more and longer nerve fibers, and also can solve the fiber crossing problem.
基金supported by the National Natural Science Foundation of China (42071420)the Major Special Project for 2025 Scientific,Technological Innovation (Major Scientific and Technological Task Project in Ningbo City)(2021Z048)the National Key Research and Development Program of China(2019YFE0125300)。
文摘Spectroscopy can be used for detecting crop characteristics. A goal of crop spectrum analysis is to extract effective features from spectral data for establishing a detection model. An ideal spectral feature set should have high sensitivity to target parameters but low information redundancy among features.However, feature-selection methods that satisfy both requirements are lacking. To address this issue,in this study, a novel method, the continuous wavelet projections algorithm(CWPA), was developed,which has advantages of both continuous wavelet analysis(CWA) and the successive projections algorithm(SPA) for generating optimal spectral feature set for crop detection. Three datasets collected for crop stress detection and retrieval of biochemical properties were used to validate the CWPA under both classification and regression scenarios. The CWPA generated a feature set with fewer features yet achieving accuracy comparable to or even higher than those of CWA and SPA. With only two to three features identified by CWPA, an overall accuracy of 98% in classifying tea plant stresses was achieved, and high coefficients of determination were obtained in retrieving corn leaf chlorophyll content(R^(2)= 0.8521)and equivalent water thickness(R^(2)= 0.9508). The mechanism of the CWPA ensures that the novel algorithm discovers the most sensitive features while retaining complementarity among features. Its ability to reduce the data dimension suggests its potential for crop monitoring and phenotyping with hyperspectral data.
基金Supported by the National Natural Science Foundation of China (No.10472034, No.10590351) the Key Technologies R&DProgram of "the 10th Five Year Plan" of China (No.2001BA303B-02).
文摘A model of the continuous melt transesterification process of bisphenol-A and diphenyl carbonate in a continuous stirred tank reactor to produce polycarbonate is presented. The model is developed by using the molecular species model of polycarbonate melt polycondensation and the modeling method of reactive flash. Liquid phase is treated as perfect mixed flow and the vapor phase is assumed following the ideal gas law. With this model, the continuous melt transesterification process of bisphenol-A and diphenyl carbonate is examined with respect to different orocess parameters.
文摘In this paper, we construct some continuous but non-differentiable functions defined by quinary dec-imal, that are Kiesswetter-like functions. We discuss their properties, then investigate the Hausdorff dimensions of graphs of these functions and give a detailed proof.
基金supported by Kunshan Science and Technology Special Fund(Social Development Category,KS18040)。
文摘BACKGROUND:The study aims to investigate an optimal indicator for changing the filter during the continuous renal replacement therapy(CRRT)in intensive care unit(ICU)patients with acute kidney injury(AKI).METHODS:Patients with AKI requiring CRRT in an ICU were randomly divided into two groups for crossover trial,i.e.,groups A and B.Patients in the group A were firstly treated with continuous veno-venous hemofiltration(CVVH),followed by continuous veno-venous hemodiafiltration(CVVHDF).Patients in the group B were firstly treated with CVVHDF followed by CVVH.Delivered doses of solutes with different molecular weights at the indicated time points between groups were compared.A correlation analysis between the delivered dose and pre-filter pressure(P_(PRE))and transmembrane pressure(P_(TM))was performed.Receiver operating characteristic(ROC)curves were constructed to evaluate the accuracy of P_(TM) as an indicator for filter replacement.RESULTS:A total of 50 cases were analyzed,27 in the group A and 23 in the group B.Delivered doses of different molecular-weight solutes significantly decreased before changing the filter in both modalities,compared with those at the initiation of treatment(all P<0.05).In the late stage of CRRT,the possible rebound of serum medium-molecular-weight solute concentration was observed.P_(TM) was negatively correlated with the delivered dose of medium-molecular-weight solute in both modalities.The threshold for predicting the rebound of serum concentration of medium-molecularweight solute by P_(TM) was 146.5 mm Hg(1 mm Hg=0.133 k Pa).CONCLUSIONS:The filter can be used as long as possible within the manufacturer’s safe use time limits to remove small-molecular-weight solutes.P_(TM) of 146.5 mm Hg may be an optimal indicator for changing the filter in CRRT therapies to remove medium-molecular-weight solutes.
文摘In this paper,a common characteristic of real number system and well ordered set is revealed and proved to be an equivalent form of the Dedekind Axiom or the Continuous Induction in R. Basing on it,we get the unified form of the mathematical induction,the transfinite induction and the continuous induction and generalize induction to totally ordered set that has the same characteristic.
文摘In this paper,a common characteristic of real number system and well ordered set is revealed and proved to be an equivalent form of the Dedekind Axiom or the Continuous Induction in R. Basing on it,we get the unified form of the mathematical induction,the transfinite induction and the continuous induction and generalize induction to totally ordered set that has the same characteristic.
文摘This paper reviews recent developments in the contin- uous processing of steels in Japan.The following items are discussed:continuous casting-direct rolling(CC-DR) process of hot-rolled strip:thermomechanical control process(TMCP)of heavy plates:in—line heat treating pro- cess of rails:direct lead patenting(DLP)process of wire rods;and fully integrated processing line(FIPL)of cold-rolled strip.
文摘Continuous casting of thin slabs is a key state project for 7th and sth five -year plans. On thebasis of foundamental works , CISRI condueted the tests of 102 heats in Lanzhou Steel Works in the periodof January 1991- June 1992. Three slab assortments of 50× 900 mm . 70 × 900 mm , 70 × 500 mm were ex-amined. In June of 1992, 412 t steel of 46 heats were cast with the efficiency of 91. 3 %. This. result meetsthe requiremeni of the state in this period. The mould, hedt transfer . casting technology and factors influ-encing slab’s qualities are investigated as well.
文摘The effect of molybdenum on the continuous cooling transformation behavior of the micro-alloyed low carbon steel containing niobium and titanium was investigated by a Gleeble 3800 thermo-mechanical simulator. The phase transformation temperature of the steel at various cooling rates was detected. The microstmcture was observed by optical microscope （OM） and scanning electronic microscope （ SEM）, and its Vickers hardness was tested. Based on these, its dynamic continuous cooling transformation （CCT） diagrams were determined. The results show that the transformation temperature from deformed austenite to acicular ferrite （AF） is decreased when Mo is added, and the formation of pro- eutectoid ferrite （F） and pearlite （P） is either inhabited or postponed. Mo can also enlarge the range of the cooling rate in forming AF, and refine the microstructure effectively.
文摘We establish the existence and uniqueness of classical solutions of the continuous casting problem with surface tension and kinetic conditions in a short time interval.
