The Activated Sludge Process(ASP) exhibits highly nonlinear properties. The design of an automatic control system that is robust against disturbance of inlet wastewater flow rate and has short process settling times i...The Activated Sludge Process(ASP) exhibits highly nonlinear properties. The design of an automatic control system that is robust against disturbance of inlet wastewater flow rate and has short process settling times is a challenging matter. The proposed control method is an I-P modi fied controller automatic control system with state variable feedback and control canonical form simulation diagram for the process. A more stable response is achieved with this type of modern control. Settling times of 0.48 days are achieved for the concentration of microorganisms,(reference value step increase of 50 mg·L-1) and 0.01 days for the concentration of oxygen(reference value step increase of 0.1 mg·L-1). Fluctuations of concentrations of oxygen and microorganisms after an inlet disturbance of5 × 103m3·d-1are small. Changes in the reference values of oxygen and microorganisms(increases by 10%, 20% and 30%) show satisfactory response of the system in all cases. Changes in the value of inlet wastewater flow rate disturbance(increases by 10%, 25%, 50% and 100%) are stabilized by the control system in short time. Maximum percent overshoot is also taken in consideration in all cases and the largest value is 25% which is acceptable. The proposed method with I-P controller is better for disturbance rejection and process settling times compared to the same method using PI controller. This method can substitute optimal control systems in ASP.展开更多
To promote the modeling standardization process of the integrated circuits, an improved electrical simulation model for a direct power injection （DPI） setup which was used to measure the conducted immunity of a 16-b...To promote the modeling standardization process of the integrated circuits, an improved electrical simulation model for a direct power injection （DPI） setup which was used to measure the conducted immunity of a 16-bit microcontroller to radio frequency aggression was investigated. Based on the existing model of the same microcontroller, the PDN module was modified by adding the core, PLL and MD network models, which could reflect the actual electric distribution situation within the microcontroller more accurately. By comparing the simulation results with the measurement results, the effectiveness of the modified model can be improved to 500 MHz, and its uncertainty is within ＋1.8 dB （＋2 dB is acceptable）. Then, to improve the simulation accuracy of the complete model in the high frequency range, the I/O model which contained the dynamic and nonlinear characteristics reflecting the variation of the internal impedance of the microcontroller with increasing the frequency of the external noise was introduced. By comparing the simulation results with the measurement results, the effectiveness of the second modified model can be improved up to 1.4 GHz with the uncertainty of ~1.8 dB. Thus, a conclusion can be reached that the proposed model can be applied to a much wider frequency range with a smaller uncertainty than the latest model of the similar type. Furthermore, associated with the electromagnetic emission testing platform model, the PDN module can also be used to predict the electromagnetic conducted and radiated emission characteristics. This modeling method can also be applied to other integrated circuits, which is very helpful to the standardization of the IC electromagnetic compatibility （EMC） modeling process.展开更多
In the Raymond mill grinding processes,high-accuracy control for the current of Raymond mill is vital to enhance the product quality and production efficiency as well as cut down the consumption of spare parts.However...In the Raymond mill grinding processes,high-accuracy control for the current of Raymond mill is vital to enhance the product quality and production efficiency as well as cut down the consumption of spare parts.However,strong external disturbances,such as variations of ore hardness and ore size,always exist.It is not easy to make the current of Raymond mill constant due to these strong disturbances.Several control strategies have been proposed to control the grinding processes.However,most of them(such as PID and MPC)reject disturbances merely through feedback regulation and do not deal with the disturbances directly,which may lead to poor control performance when strong disturbances occur.To improve disturbance rejection performance,a control scheme based on PI and disturbance observer is proposed in this work.The scheme combines a feedforward compensation part based on disturbance observer and a feedback regulation part using PI.The test results illustrate that the proposed method can obtain remarkable superiority in disturbance rejection compared with PI method in the Raymond mill grinding processes.展开更多
文摘The Activated Sludge Process(ASP) exhibits highly nonlinear properties. The design of an automatic control system that is robust against disturbance of inlet wastewater flow rate and has short process settling times is a challenging matter. The proposed control method is an I-P modi fied controller automatic control system with state variable feedback and control canonical form simulation diagram for the process. A more stable response is achieved with this type of modern control. Settling times of 0.48 days are achieved for the concentration of microorganisms,(reference value step increase of 50 mg·L-1) and 0.01 days for the concentration of oxygen(reference value step increase of 0.1 mg·L-1). Fluctuations of concentrations of oxygen and microorganisms after an inlet disturbance of5 × 103m3·d-1are small. Changes in the reference values of oxygen and microorganisms(increases by 10%, 20% and 30%) show satisfactory response of the system in all cases. Changes in the value of inlet wastewater flow rate disturbance(increases by 10%, 25%, 50% and 100%) are stabilized by the control system in short time. Maximum percent overshoot is also taken in consideration in all cases and the largest value is 25% which is acceptable. The proposed method with I-P controller is better for disturbance rejection and process settling times compared to the same method using PI controller. This method can substitute optimal control systems in ASP.
基金Project(2007dfa71250) supported by the International Science and Technology Cooperative Program of ChinaProject(20062250) supported by the Doctor Fund of North China Electric Power University, China
文摘To promote the modeling standardization process of the integrated circuits, an improved electrical simulation model for a direct power injection （DPI） setup which was used to measure the conducted immunity of a 16-bit microcontroller to radio frequency aggression was investigated. Based on the existing model of the same microcontroller, the PDN module was modified by adding the core, PLL and MD network models, which could reflect the actual electric distribution situation within the microcontroller more accurately. By comparing the simulation results with the measurement results, the effectiveness of the modified model can be improved to 500 MHz, and its uncertainty is within ＋1.8 dB （＋2 dB is acceptable）. Then, to improve the simulation accuracy of the complete model in the high frequency range, the I/O model which contained the dynamic and nonlinear characteristics reflecting the variation of the internal impedance of the microcontroller with increasing the frequency of the external noise was introduced. By comparing the simulation results with the measurement results, the effectiveness of the second modified model can be improved up to 1.4 GHz with the uncertainty of ~1.8 dB. Thus, a conclusion can be reached that the proposed model can be applied to a much wider frequency range with a smaller uncertainty than the latest model of the similar type. Furthermore, associated with the electromagnetic emission testing platform model, the PDN module can also be used to predict the electromagnetic conducted and radiated emission characteristics. This modeling method can also be applied to other integrated circuits, which is very helpful to the standardization of the IC electromagnetic compatibility （EMC） modeling process.
基金Projects(61504027,61573099)supported by the National Natural Science Foundation of ChinaProject(BK20140647)supported by the Natural Science Foundation of Jiangsu Province,ChinaProject supported by the Priority Academic Program Development of Jiangsu Higher Education Institutions,China
文摘In the Raymond mill grinding processes,high-accuracy control for the current of Raymond mill is vital to enhance the product quality and production efficiency as well as cut down the consumption of spare parts.However,strong external disturbances,such as variations of ore hardness and ore size,always exist.It is not easy to make the current of Raymond mill constant due to these strong disturbances.Several control strategies have been proposed to control the grinding processes.However,most of them(such as PID and MPC)reject disturbances merely through feedback regulation and do not deal with the disturbances directly,which may lead to poor control performance when strong disturbances occur.To improve disturbance rejection performance,a control scheme based on PI and disturbance observer is proposed in this work.The scheme combines a feedforward compensation part based on disturbance observer and a feedback regulation part using PI.The test results illustrate that the proposed method can obtain remarkable superiority in disturbance rejection compared with PI method in the Raymond mill grinding processes.
