Advanced Materials Research Vols. 383-390

Abstract: A new method for estimating the moment of inertia of engine generator set was proposed in this paper, which was defined as Governor Sensitivity Test Method (GSTM). In this method, the moment of inertia of engine generator set was estimated by means of measure transient speed change of engine generator set when the engine load increases suddenly. In the present, there have been some methods for estimating the moment of inertia of engine, such as, Additional Mass Method, Running Down Test Method and Accelerating- Decelerating Method Under No Load. These methods for estimating the moment of inertia of engine generator set all have shortcomings on accuracy or operability. These shortcomings have been overcome by using the GSTM method proposed in this paper. It is easy to operate, and the factors affecting estimation errors are small. In this paper, the basic principle of the GSTM method was discussed. The factors affecting estimation errors ware analyzed. An example of calculating the moment of inertia of an engine generator set using the GSTM method was presented. The result of calculating the moment of inertia of engine generator set was used to simulate the transient speed response of an engine generator set. The GSTM method was verified to be practical by comparing the results of simulation and experiment.

Abstract: Quenching is the technology that a metal work piece heated to propriety temperature for a while is being put into quenching medium suddenly. Quenching can improve the rigidity and abrasion resistance of metal. Making use of PLC to control quenching process, the quenching has simple technology, cheap price, stable function and convenient operation. This quenching system constitutes heating system, quenching liquid cycle system, hydraulic pressure system and electric control system. The quenching machine control system introduced in this thesis has three control modes, Manual, Auto and Try-piece designed utilized S7-PLC. This system can rise and fall worktable, clamp and relax work piece, sway forward and backwards, unload-work piece control high degree by approach-switch, produce many kinds of auto-spring plate, meet the requirement of auto-spring plate nowadays. It is presented in this thesis detailed, control-demand, element list for electric control, I/O distribute list, control LAD and improved measure for system in the end.

Abstract: Solid acid catalyst has high catalytic esterification activity but with a free acid excess problem. In this paper, washing pretreatments were adopted in the catalyst preparation processes and their influences on catalytic activity and residual free acid amount were investigated. Residual free acid amount can be reduced by 33% with both washing before calcinations and washing after calcinations pretreatments. But their influences on catalyst activities were different. Washing before calcinations pretreatment reduced the catalytic activity from 80.29% to 57.72% while the other washing pretreatment had little influence on the catalyst activity. In order to describe the influence mechanism of washing pretreatments, catalysts were characterized by FT-IR and XRD. Finally, typical compounds in bio-oil were selected to form a bio-oil model compounds system. The catalyst pretreated by washing after calcinations was used on the esterification research of this bio-oil model system. The volume ratio of propanol to bio-oil model compound was 3:1. The reaction temperature was 90 °C and the amount of catalyst was 2wt% of total liquid mass. Combined with the GC-MS qualitative and quantitative results, carboxylic acids, such as formic acid, acetic acid, propionic acid were converted to esters effectively.

Abstract: Aimed at the self-excited vibration of caused by unreasonable clearance in wearing ring of the Francis turbine, whole flow passage of prototype hydraulic turbine which contains the clearance in wearing ring is numerically calculated by computational fluid dynamics software CFX based on N-S equation and RNG k-turbulence model. The result shows that the flow field in front of inlet of runner is unstable extremely, even if a tiny disturbance effects on, which will be out-of-balance symmetrically in the radial direction, then the force of runner will be unbalance, which will cause vibration of the hydraulic turbine. As well as, a reasonable clearance in wearing ring of the Francis turbine will reduce the impact of the water in the inlet of the clearance, and self-excited vibration of the hydraulic turbine will eliminate.

Abstract: In order to meet the requirements of agricultural production automation, a PC-based opening navigation system for agricultural machinery is designed, which is composed of PC, data acquisition cards, electromagnetic induction sensors, high-frequency electromagnetic generator, DC servo motor and mechanical part. The track of the mobile platform is led by a wire with high-frequency currents laid under the field. The position can be determined by a pair of electromagnetic induction sensors installed in the machine. The traveling path is planed by computer according to information of electromagnetic induction sensor and automatic walking of agricultural machinery is achieved. Based on Visual C + + 6.0 platform, a system software is developed and human-computer interface with good interaction is designed. The results show that, straight navigation accuracy is ± 1.5cm within 10m; the navigation accuracy is ± 3cm when the turning radius is 0.5m. Experiments explain that the system owns high real-time performance and dependability, and that it has a good application prospect.

Abstract: The inner parameters and outside load of operating-side and driving-side subsystems of rolling mill are different. This difference can lead to an unequal horizontal thickness difference distribution of strip. Synchronous system is being widely applied in industrial field, in order to solve the problem of synchronization control based on two cylinders system of rolling mill, a mathematical model of hydiaulic system is presented, then, a kind of dynamic synchronous control strategy is applied. In the part of controller, the parameters of PID controller are adjusted by self-study. So the PID controller has the capability of self-adaptation. Experimental results show that the method can reduce synchronization error from to and improve the quality of the plate and strip.

Abstract: In this paper we propose a control scheme of electromechanical actuator with optical encoder feedback. Controlled object is the simplified model of a DC motor while feedback device is an optical encoder. Encoder model is established after analyzing its principle and signal characteristic. Many velocity estimation methods have been compared and the least squares fit filter is selected for our design because of its simple algorithm and capability of predicting velocity and position. Using these predictions as feedback, a variable structure controller based on exponential approach law is adopted in the actuator close-loop control. The relationship between system performance and encoder resolution is exposed. This scheme can be implemented easily with low cost and convenient interface. Its validity is proved by simulation results.

Abstract: With the rapid growth of the national economy, the demand for electricity is increasing rapidly. In order to ensure electric power system operates safely and stably, much attention has been paid to insulation condition and lightning proof abilities of HV transmission lines. Nowadays the study of lightning protection of transmission line, which takes districts as the research object, has certain limitations. To provide a more rational basis for insulation design of the new transmission lines as well as insulation improvement in the old, this paper brings in a new analysis method based on ArcGIS. It is also taking the environmental factors, such as landscape along the transmission lines, into consideration. This method first filters and statistically analyzes lightning location data, and establishes assessment model of lightning proof abilities of transmission lines, which can serve as reference for finding the segment struck by lightning. In order to verify the feasibility of the model, this paper took a 220kV transmission line of a region in the Pearl River Delta as an example, and analyzed the distribution of parameters of lightning activities for the past decade. The result shows that the segments where flashover trip occurred have great relevance with the results of the data analysis. It is true that the model can be provided as a reference to the improvement of the insulation level of lines.

Abstract: Fuel supply advanced angle is one of effective parameters in monitoring the state or diagnosing the fault of diesel engine. So it is important to study fast and accurate detection method of fuel supply advanced angle. The embedded sensor is used to measure injection waveform of high-pressure fuel tube. The detection algorithm is established, and the fuel supply advanced angle is calculated by comparing the injection waveform with top dead center signal. In situ calculated advanced angle coincides with the rated parameter of diesel provided by manufacturer and verify the accuracy of the method.

Abstract: To the video that contains the target, a method is proposed to create the background model based on the mixed Gauss. And the target locating method based on the blob analysis and blob filtering, the anti-noise ability and filter robustness of tracking is improved. The kalman filter and the particle filter are separately used to pass and update the foreground target’s posterior probability distribution. Finally the kalman filter and the particle filter's are compared and that builds the foundation of the further development.