Design and Comparison of Strategies for Level Control in a Nonlinear Tank

In this work, a study of the water level control of an inverted conical tank system is presented. This type of tank has highly nonlinear mathematical and dynamic characteristics. Four control strategies are designed, applied, and compared, namely classical Proportional–Integral–Derivative (PID), Gain Scheduling (GS), Internal Model Control (IMC), and Fuzzy Logic (FL). To determine which of the designed control strategies are the most suitable for an inverted conical tank, a comparative study of the behavior of the system is carried out. With this purpose, and considering situations much closer to reality, a variety of scenarios, such as step responses, random input disturbances, and momentary load disturbances, are conducted. Additionally, performance indexes (error- and statistics-based) are calculated to assess the system’s response.

Application of Co-Simulation in Noise and Vibration Analysis of Shearer

In order to investigate the noise and vibration characteristics of shearer, through the analysis of shearer found that the nonlinear instantaneous impact loading caused by cutting pick in the cutting process is the main disturbance source of the noise and vibration,the simulation pro- gramme of cutting pick momentary load was worked out by the implementation of MATLAB. The vibration of the key parts was obtained through the analysis of the rigid-flex coupled model of shearer which was established based on a co-simulation virtual prototype frame,and found that the vibration of the shell stretched out side is more severe, the shell subjacent ear under a larger dynamic stress, the planet carrier has a evident torsional deformation. According to analysis results, the optimized shell vibration significantly weakened, mechanical performance improved drama- tically. The analysis results provide an important basis for improving the shearer cutting unit design and reducing the noise level of coal face.

Distribution of Boiler Load

The paper deals with the load distribution between a number of boilers operating in parallel, with a view to obtaining minimum fuel consumption. The application of the theory of minima leads to a graphical solution, and it is demonstrated that maximum plant efficiency can generally be obtained only when all boilers share in the load fluctuations to an extent depending on the input-output characteristics of the various boilers and on the momentary load. The division of a plant into groups of boilers operating at base load and fluctuating load, respectively, is generally not economical. Automatic boiler control not only increases the operating efficiency of the individual boiler but can be used also for maintaining the most economical load distribution between the units, and thereby also raises the efficiency of the plant as a whole. The paper also discusses how many and which units should be used to cover a given load range, and when a boiler ought to be banked or connected to the line again. This depends upon the ratio between standby and operating periods; but generally it will be more economical to operate all boilers down to their minimum load than to bank some of them. The same principles of load distribution can be applied to the parallel operation of any kind of machines other than boilers.