Applied Mechanics and Materials Vols. 433-435

Abstract: Based on these characteristics of dissolved oxygen control in sewage treatment aeration process, such as nonlinearity, large time delay in a timely manner and difficult to model accurately, this paper puts forward an intelligent control strategy of dissolved oxygen. First, make intelligent dynamic dissolved oxygen value setting according to water quality parameters as the feed forward control, and then Fuzzy PID control and conventional PID control fan control systems compose a cascade control system to ensure the stability of dissolved oxygen value in given value. I used the simulation and experimental analysis. The results show that under the condition of ensuring water quality, the control strategy can reduce aeration energy consumption and guarantee the stability of system.

Abstract: This paper introduces the SVPWM mechanism firstly and the software and hardware scheme of current loop in servo motor is designed; it also contains the control strategy and the current sampling principle. The dead time compensation problem in the inverter of the motor drive is discussed deeply. In the end, the software realization method of the interruption of current loop is presented in details.

Abstract: Aiming at the nonlinear and coupling phenomena of temperature and humidity changes appearing in the course of tea fixation, this paper introduces the fuzzy control technology in the process of making tea. STM32F107 microcontroller is as the core of the whole system and the multi-point detection system is used in real-time collection of two parameters of temperature and humidity . In addition, data transmission is realized between PC and I2C, SPI bus. The control rules and parameters of controller are formulated and the temperature and humidity of tea fixation multi-parameter control are realized. Fuzzy decoupling control is adopted to meet the process requirement of temperature and humidity change in process. It improves the precision of temperature and humidity control and the quality of tea.

Abstract: According to the rotate speed switching problems of rapidity and stability during single channel rolling control for fixed canard rudder, the control algorithm based on active disturbance rejection controller (ADRC) was presented to control the rudders rotate speed switching. The working principle of fixed canard rudder was analyzed, and the mathematical model of the rudder was established, and the ADRC cascade controller for the rudder was designed. The simulation results indicates that not only the proposed rotate speed switching control strategy for the rudder is feasible, but also the proposed ADRC algorithm improves the rapidity of speed switching process, with switching time of 30ms, no overshoot, and very good robustness under inner perturbation and external disturbance with nonlinear friction considered.

Abstract: For the strong coupling problem of three-phase bearingless induction motor which is a multi- variable and nonlinear object, a kind of decoupling control strategy based on inverse system method is proposed. The reversibility of torque subsystem was analyzed based on rotor flux orientation, and the decoupling control strategy based on inverse system method was analyzed. Then the torque system was decoupled into two second-order linear subsystems, i.e. the rotor speed subsystems and the rotor flux subsystems. The suspension system adopts negative feedback control; the required air-gap flux linkage of torque system was obtained from the rotor flux and stator current. Finally, synthesis and simulation of the overall control system were researched. Simulation results demonstrate that good performance of decoupling control can be achieved. The presented control strategy is feasible and available.

Abstract: Abstract: In order to evaluate motion performs of a numerical control machine tool objectively, the matter-element model for the motion performs evaluation of the NC was established based on extenics theory, the motion performs evaluation indexes of NC was made of multiple elements. The relational degree was calculated by introducing the relational function in the extension set theory, and the evaluation indexes weight coefficient of NC were defined by using the 1-9 scale law in AHP (the analytic hierarchy process). A numerical control machine tool as a study object, the motion performs was studied by using the extenics theory. The result indicated that the motion performs of this NC was good, the evaluation method possesses a certain practicability.

Abstract: In order to study the performance of packing, compression and baling and obtain the influence of working parameters on complete machine, a test-bed was developed based on the packing, compression and baling devices of baler. The measure system consists of IPC, sensors, a data acquisition card and a type of software programmed by using VC++. It can real-time collect, display, process and analyze the parameters and loads of the working parts. Wheat straws with 40% moisture content were used to carry on compression and baling experiments. The test results show that average total power consumption of the working parts, average force acting on the plunger and average force acting on the connecting rod is 3.44 kW, 873.5 N and 11965.8 N respectively when the straw feed rate is 0.8 kg/s and the compression frequency of the plunger is 75 strokes per minute. The bale density can reach up to 125 kg/m³.

Abstract: A mathematic model was established to simulate the process of AUV (autonomous undersea vehicle) launching a towed buoyage. Based on the lumped mass method and moment theorem and angular momentum theorem, dynamic equations of the cable and the buoyage were developed, respectively. Then the boundary conditions and the numerical scheme to deal with the cable with non-fixed length were presented. Moreover, the process of AUV launching a towed cable was simulated. By using the model, the results show the trajectory of buoyage and shape of towed cable can be well predicted.

Abstract: In order to reflect the complex effect of acceleration and air pressure, this paper introduces a new synchronously simulate technology and analyses the principle of the synchronously simulate. The paper also designs the structure and software of the control system. At last, the paper shows the result the application. The result shows that the system is simple, reliable, and the synchronization between acceleration and air pressure is very high. The analysis can also provide a reference for similar centrifuge design personnel.

Abstract: Renewable energy resources (RES) are being increasingly connected in distribution systems by utilizing power electronic converters. However, the extensive use of power electronics has resulted in a rise in power quality (PQ) concerns faced by the utility. A novel control strategy implementing reference compensation current was proposed in this paper. So that these grid-connected inverters can achieve maximum benefits when they installed in 3-phase 4-wire distribution systems. The inverter is controlled to perform as a multi-function device by incorporating active power filter functionality. The inverter can thus be utilized as: 1) power converter to transfer active power from RES to the grid, and 2) load reactive power demand support; 3) current harmonics compensation at PCC; and 4) current unbalance and neutral current compensation in case of 3-phase 4-wire system. Moreover, with adequate control of grid-interfacing inverter, all the four objectives can be accomplished either individually or simultaneously. Simulation results show the validity and capability of the novel proposed control strategy.