Pump controlled motor electrohydraulic servo systems are much used in circumstances where high power drive is needed. This kind of system has the advantage of energy-saving. But, it also has some defects that have to ...Pump controlled motor electrohydraulic servo systems are much used in circumstances where high power drive is needed. This kind of system has the advantage of energy-saving. But, it also has some defects that have to be improved. Microcomputer control of a pump controlled motor electrohydraulic servo system is studied. A PID controller is first adopted on the closed loop control system, and experimental results are obtained. Then, a model reference adaptive controller is designed and realised on the same system applying a single board microcomputer. Experimental results show that the dynamic properties of the adaptive control system is much better than those of the PID system under different inertia load conditions.展开更多
Fortifying commonly consumed foods and beverages offers a great opportunity of filling the nutrient gap between actual and the needed nutrient intakes of young children. Ready-to-drink beverage as a vehicle for fortif...Fortifying commonly consumed foods and beverages offers a great opportunity of filling the nutrient gap between actual and the needed nutrient intakes of young children. Ready-to-drink beverage as a vehicle for fortification is easy to administer, more consistent and least obstructive, because it can be consumed without further processing/cooking. This study aimed to evaluate the effectiveness of fortified beverage on the improving of iron status and school performance test of schoolchildren. About 5,000 schoolchildren aged 6-12 years old from 19 schools in Quirino province, Philippines were invited to participate in the study. Samples of 4,875 children with parental consent were screened for hemoglobin and serum ferritin levels. About 4,495 children had complete participation in the school performance test, which were developed and administered by school supervisors. Children were fed 200 mL ready-to-drink juice fortified with iron, zinc, lysine, vitamins A and C for 120 d. The beverage was delivered through the baseline. At end of the intervention, only 1,050 children had complete data set and the anemia rate reduced from 100% to 60%. Iron deficiency has increased insignificantly from 3.6% to 4.5%. Mean percentage of test scores increased significantly between base and end of the study： English （40% to 60%）, math （35% to 58%） and science （32% to 58%）. In conclusion, consumption of 200 mL fortified juice drink had contributed to the reduction of anemia and increased tests scores of children.展开更多
Using the Nevanlinna value distribution theory of meromorphic function,we investigate the existence problem of admissible solutions of higher-order algebraic differential equations systems,and obtain a result concerni...Using the Nevanlinna value distribution theory of meromorphic function,we investigate the existence problem of admissible solutions of higher-order algebraic differential equations systems,and obtain a result concerning admissible components of solution.展开更多
Most of the MHP （micro hydro power） plants use ELC （electronic load controller） for speed control. Various types of ELC have been developed so far. A dummy ballast load is connected across each phase of generator ...Most of the MHP （micro hydro power） plants use ELC （electronic load controller） for speed control. Various types of ELC have been developed so far. A dummy ballast load is connected across each phase of generator terminals and ELC controls the power consumed by the ballast load to result in constant speed operation. The ELC developed so far uses thyristor switches in each phase to control ballast load power. The ELC senses the system frequency and comparing it with reference frequency, it generates a common value of firing angle for all three thyristor pairs of each phase. The performance of such ELC is not perfect for unbalanced consumers load connected in each phase, which overloads the generator. This paper presents an advanced type of ELC which senses frequency as well as consumer＇s load current of each phase and fires the thyristor pairs with different value of firing angles for different phases. This solves the problem of overloading of the generator with unbalanced consumer＇s load. Simutink model is developed to perform transient analysis of the proposed scheme and the prototype of hardware is also fabricated. The simulation results and experimental results are presented.展开更多
Learning control for gradually varying references in iteration domain was considered in this research, and a composite iterative learning control strategy was proposed to enable a plant to track unknown iteration-depe...Learning control for gradually varying references in iteration domain was considered in this research, and a composite iterative learning control strategy was proposed to enable a plant to track unknown iteration-dependent trajectories. Specifically, by decoupling the current reference into the desired trajectory of the last trial and a disturbance signal with small magnitude, the learning and feedback parts were designed respectively to ensure fine tracking performance. After some theoretical analysis, the judging condition on whether the composite iterative learning control approach achieves better control results than pure feedback contro! was obtained for varying references. The convergence property of the closed-loop system was rigorously studied and the saturation problem was also addressed in the controller. The designed composite iterative learning control strategy is successfully employed in an atomic force microscope system, with both simulation and experimental results clearly demonstrating its superior performance.展开更多
基金The Project Supported by Doctoral Programme Foundation of Institution of Higher Education
文摘Pump controlled motor electrohydraulic servo systems are much used in circumstances where high power drive is needed. This kind of system has the advantage of energy-saving. But, it also has some defects that have to be improved. Microcomputer control of a pump controlled motor electrohydraulic servo system is studied. A PID controller is first adopted on the closed loop control system, and experimental results are obtained. Then, a model reference adaptive controller is designed and realised on the same system applying a single board microcomputer. Experimental results show that the dynamic properties of the adaptive control system is much better than those of the PID system under different inertia load conditions.
文摘Fortifying commonly consumed foods and beverages offers a great opportunity of filling the nutrient gap between actual and the needed nutrient intakes of young children. Ready-to-drink beverage as a vehicle for fortification is easy to administer, more consistent and least obstructive, because it can be consumed without further processing/cooking. This study aimed to evaluate the effectiveness of fortified beverage on the improving of iron status and school performance test of schoolchildren. About 5,000 schoolchildren aged 6-12 years old from 19 schools in Quirino province, Philippines were invited to participate in the study. Samples of 4,875 children with parental consent were screened for hemoglobin and serum ferritin levels. About 4,495 children had complete participation in the school performance test, which were developed and administered by school supervisors. Children were fed 200 mL ready-to-drink juice fortified with iron, zinc, lysine, vitamins A and C for 120 d. The beverage was delivered through the baseline. At end of the intervention, only 1,050 children had complete data set and the anemia rate reduced from 100% to 60%. Iron deficiency has increased insignificantly from 3.6% to 4.5%. Mean percentage of test scores increased significantly between base and end of the study： English （40% to 60%）, math （35% to 58%） and science （32% to 58%）. In conclusion, consumption of 200 mL fortified juice drink had contributed to the reduction of anemia and increased tests scores of children.
基金Supported by the NSF of Guagndong Province(04010474)
文摘Using the Nevanlinna value distribution theory of meromorphic function,we investigate the existence problem of admissible solutions of higher-order algebraic differential equations systems,and obtain a result concerning admissible components of solution.
文摘Most of the MHP （micro hydro power） plants use ELC （electronic load controller） for speed control. Various types of ELC have been developed so far. A dummy ballast load is connected across each phase of generator terminals and ELC controls the power consumed by the ballast load to result in constant speed operation. The ELC developed so far uses thyristor switches in each phase to control ballast load power. The ELC senses the system frequency and comparing it with reference frequency, it generates a common value of firing angle for all three thyristor pairs of each phase. The performance of such ELC is not perfect for unbalanced consumers load connected in each phase, which overloads the generator. This paper presents an advanced type of ELC which senses frequency as well as consumer＇s load current of each phase and fires the thyristor pairs with different value of firing angles for different phases. This solves the problem of overloading of the generator with unbalanced consumer＇s load. Simutink model is developed to perform transient analysis of the proposed scheme and the prototype of hardware is also fabricated. The simulation results and experimental results are presented.
基金Projects(61127006,61325017)supported by the National Natural Science Foundation of China
文摘Learning control for gradually varying references in iteration domain was considered in this research, and a composite iterative learning control strategy was proposed to enable a plant to track unknown iteration-dependent trajectories. Specifically, by decoupling the current reference into the desired trajectory of the last trial and a disturbance signal with small magnitude, the learning and feedback parts were designed respectively to ensure fine tracking performance. After some theoretical analysis, the judging condition on whether the composite iterative learning control approach achieves better control results than pure feedback contro! was obtained for varying references. The convergence property of the closed-loop system was rigorously studied and the saturation problem was also addressed in the controller. The designed composite iterative learning control strategy is successfully employed in an atomic force microscope system, with both simulation and experimental results clearly demonstrating its superior performance.
