Advanced feedback control for optimal operation of mineral grinding process is usually based on the model predictive control (MPC) dynamic optimization. Since the MPC does not handle disturbances directly by controlle...Advanced feedback control for optimal operation of mineral grinding process is usually based on the model predictive control (MPC) dynamic optimization. Since the MPC does not handle disturbances directly by controller design, it cannot achieve satisfactory effects in controlling complex grinding processes in the presence of strong disturbances and large uncertainties. In this paper, an improved disturbance observer (DOB) based MPC advanced feedback control is proposed to control the multivariable grinding operation. The improved DOB is based on the optimal achievable H 2 performance and can deal with disturbance observation for the nonminimum-phase delay systems. In this DOB-MPC advanced feedback control, the higher-level optimizer computes the optimal operation points by maximize the profit function and passes them to the MPC level. The MPC acts as a presetting controller and is employed to generate proper pre-setpoint for the lower-level basic feedback control system. The DOB acts as a compensator and improves the operation performance by dynamically compensating the setpoints for the basic control system according to the observed various disturbances and plant uncertainties. Several simulations are performed to demonstrate the proposed control method for grinding process operation.展开更多
The investigation was carried out on the technical problems of finishing the inner surface of elbow parts and the action mechanism of particles in elbow precision machining by abrasive flow.This work was analyzed and ...The investigation was carried out on the technical problems of finishing the inner surface of elbow parts and the action mechanism of particles in elbow precision machining by abrasive flow.This work was analyzed and researched by combining theory,numerical and experimental methods.The direct simulation Monte Carlo(DSMC)method and the finite element analysis method were combined to reveal the random collision of particles during the precision machining of abrasive flow.Under different inlet velocity,volume fraction and abrasive particle size,the dynamic pressure and turbulence flow energy of abrasive flow in elbow were analyzed,and the machining mechanism of particles on the wall and the influence of different machining parameters on the precision machining quality of abrasive flow were obtained.The test results show the order of the influence of different parameters on the quality of abrasive flow precision machining and establish the optimal process parameters.The results of the surface morphology before and after the precision machining of the inner surface of the elbow are discussed,and the surface roughness Ra value is reduced from 1.125μm to 0.295μm after the precision machining of the abrasive flow.The application of DSMC method provides special insights for the development of abrasive flow technology.展开更多
The most important grinding processes were realized in a single pass of the grinding wheel,such as continuous path controlled grinding (CPCG/Peelgrinding/HSP),CPCG with reduced contact of the grinding wheel (Quickpoin...The most important grinding processes were realized in a single pass of the grinding wheel,such as continuous path controlled grinding (CPCG/Peelgrinding/HSP),CPCG with reduced contact of the grinding wheel (Quickpoint),single-pass longitudinal internal grinding,creep feed grinding (CFG),longitudinal cylindrical grinding with grinding wheels made of conventional abrasive materials and longitudinal internal cylindrical grinding using grinding wheels with zone-diversified structure.展开更多
This paper studies desizing and polishing of naturally colored cotton with different enzyme. The reactivity of cellulases was measured. The percentage of decrement, bulkiness and color difference of fabrics both befor...This paper studies desizing and polishing of naturally colored cotton with different enzyme. The reactivity of cellulases was measured. The percentage of decrement, bulkiness and color difference of fabrics both before and after eco-finishing were tested. The reasons were analyzed. The results indicates that the desizing of amylase can be applied on naturally colored cotton, and cellulases have polishing effect on it. Moreover eco-finishing with enzyme can provide many better properties to naturally colored cotton than that of normal finishing. Also this process has no pollution as enzyme can be degraded by bioreaction.展开更多
This study represents an approach to investigate a force controlled short-stroke honing process and especially the dependency between the type of finishing tool and the resulting shape accuracy. Based on a finite elem...This study represents an approach to investigate a force controlled short-stroke honing process and especially the dependency between the type of finishing tool and the resulting shape accuracy. Based on a finite element analysis and a validation with special pressure measurement films, the contact mechanisms between the finishing tool and the workpiece are analyzed. In order to achieve a high surface quality without reducing the shape accuracy, the influence of different finishing tools with an individual material behavior on the resulting shape accuracy have been analyzed. With a variation of the geometry of the finishing tool as well as of the workpiece, different loading cases between the tool and the workpiece are considered in the finite element simulation. These results, combined with experimental investigations with different finishing films lead to an improvement of the surface quality without reducing the shape accuracy.展开更多
基金Supported by the National Natural Science Foundation of China (61104084, 61290323)the Guangdong Education University-Industry Cooperation Projects (2010B090400410)
文摘Advanced feedback control for optimal operation of mineral grinding process is usually based on the model predictive control (MPC) dynamic optimization. Since the MPC does not handle disturbances directly by controller design, it cannot achieve satisfactory effects in controlling complex grinding processes in the presence of strong disturbances and large uncertainties. In this paper, an improved disturbance observer (DOB) based MPC advanced feedback control is proposed to control the multivariable grinding operation. The improved DOB is based on the optimal achievable H 2 performance and can deal with disturbance observation for the nonminimum-phase delay systems. In this DOB-MPC advanced feedback control, the higher-level optimizer computes the optimal operation points by maximize the profit function and passes them to the MPC level. The MPC acts as a presetting controller and is employed to generate proper pre-setpoint for the lower-level basic feedback control system. The DOB acts as a compensator and improves the operation performance by dynamically compensating the setpoints for the basic control system according to the observed various disturbances and plant uncertainties. Several simulations are performed to demonstrate the proposed control method for grinding process operation.
基金Projects(51206011,U1937201)supported by the National Natural Science Foundation of ChinaProject(20200301040RQ)supported by the Science and Technology Development Program of Jilin Province,China+1 种基金Project(JJKH20190541KJ)supported by the Education Department of Jilin Province,ChinaProject(18DY017)supported by Changchun Science and Technology Program of Changchun City,China。
文摘The investigation was carried out on the technical problems of finishing the inner surface of elbow parts and the action mechanism of particles in elbow precision machining by abrasive flow.This work was analyzed and researched by combining theory,numerical and experimental methods.The direct simulation Monte Carlo(DSMC)method and the finite element analysis method were combined to reveal the random collision of particles during the precision machining of abrasive flow.Under different inlet velocity,volume fraction and abrasive particle size,the dynamic pressure and turbulence flow energy of abrasive flow in elbow were analyzed,and the machining mechanism of particles on the wall and the influence of different machining parameters on the precision machining quality of abrasive flow were obtained.The test results show the order of the influence of different parameters on the quality of abrasive flow precision machining and establish the optimal process parameters.The results of the surface morphology before and after the precision machining of the inner surface of the elbow are discussed,and the surface roughness Ra value is reduced from 1.125μm to 0.295μm after the precision machining of the abrasive flow.The application of DSMC method provides special insights for the development of abrasive flow technology.
文摘The most important grinding processes were realized in a single pass of the grinding wheel,such as continuous path controlled grinding (CPCG/Peelgrinding/HSP),CPCG with reduced contact of the grinding wheel (Quickpoint),single-pass longitudinal internal grinding,creep feed grinding (CFG),longitudinal cylindrical grinding with grinding wheels made of conventional abrasive materials and longitudinal internal cylindrical grinding using grinding wheels with zone-diversified structure.
文摘This paper studies desizing and polishing of naturally colored cotton with different enzyme. The reactivity of cellulases was measured. The percentage of decrement, bulkiness and color difference of fabrics both before and after eco-finishing were tested. The reasons were analyzed. The results indicates that the desizing of amylase can be applied on naturally colored cotton, and cellulases have polishing effect on it. Moreover eco-finishing with enzyme can provide many better properties to naturally colored cotton than that of normal finishing. Also this process has no pollution as enzyme can be degraded by bioreaction.
文摘This study represents an approach to investigate a force controlled short-stroke honing process and especially the dependency between the type of finishing tool and the resulting shape accuracy. Based on a finite element analysis and a validation with special pressure measurement films, the contact mechanisms between the finishing tool and the workpiece are analyzed. In order to achieve a high surface quality without reducing the shape accuracy, the influence of different finishing tools with an individual material behavior on the resulting shape accuracy have been analyzed. With a variation of the geometry of the finishing tool as well as of the workpiece, different loading cases between the tool and the workpiece are considered in the finite element simulation. These results, combined with experimental investigations with different finishing films lead to an improvement of the surface quality without reducing the shape accuracy.
