Applied Mechanics and Materials Vols. 511-512

Abstract: Ultralow frequency vibration tables can easily be imposed external vibration interferences when they work. These interferences result to output distortion and the reduction of the calibration precision. A system with active vibration isolation control can effectively reduce the measure distortion. The principle of active control is the negative feedback method in vibration isolation. A composite feedback system was introduced that based on several different feedback variables. The frequency characteristic of the system was analysed. We simulated MATLAB at 0.1Hz and 1Hz. It is obvious that a better vibration isolation is effective by composite feedback system based on negative feedback method.

Abstract: In this paper, the vertex stability problem for a class of grey discrete dynamic systems was investigated by means of the matrix eigenvalues theory and spectral radius approach. Several necessary and sufficient conditions are obtained which can guarantee the vertex stability of grey discrete dynamic systems. The equivalence relation between the vertex stability and Schur stability of grey discrete dynamic systems , as well as the equivalence relation between the vertex stability for grey discrete dynamic systems and its boundary matrix are established.

Abstract: In the paper, we analyze the distributed flocking algorithms with communication noise. Under the Boid model, flocking algorithm with communication noise is easy to diverge. In order to improve the convergence performance of flocking algorithms with communication noise, and overcome the impact brought by communication noise on flocking algorithm, in the paper, a distributed flocking algorithm based on SO-DCT distributed consensus algorithm is proposed. The second-order flocking algorithm under the Boid model is analyzed, and simulations are done. Results show that the second-order distributed flocking algorithm can reach cohesion, and its convergence performance is better than that of the first-order distributed flocking algorithm, moreover, the impact of communication noise on the second-order flocking algorithm is smaller.

Abstract: Dome gas lift is one of the core link in the process of the construction of a large LNG (liquefied natural gas) storage tank. The process of traditional gas lift is relying on the working experience to control the gas pressure inside the storage tank, which has low control precision and poor operability. In this paper, a kind of PID control method was designed through the analysis of the gas lift process and the data was extracted as the feedback parameters by multi-point gas pressure sensors. Simulation was proceeded by the MATLAB software. The results show that, this PID control method can automatically adjust the pressure of the process of gas lift. And it also has fast, stable and reliable control performance. This method has important practical value in improving the control precision of the large LNG storage tank gas lift.

Abstract: To address the control strategy optimization issue of Electric Vehicles (EV), this paper designed distributed control system based on CAN network for EV, constructed a real time EV control model by Simulink and Stateflow. The model was converted to C code After simulating of the model had been conducted on PC, then the C code was downloaded to the rapid prototyping platform ControlBase_VT, and a model based prototyping controller for EV was developed. The prototype controller was mounted to a car, and vehicle control strategy is tested, analyzed and optimized. Using rich hardware resources of rapid prototyping platform and the conversion function from simulink model to executable C code, rapid development and optimization of control strategies is easy to be achieved, simple method is provided for the development, validation and optimization of control strategy, and development period and cost is reduced compared to self-built based hardware development.

Abstract: Based on the requirement of the application and development of modern logistics technology, combined with the computer technology, communication technology and information technology, this paper studies the concrete scheme of automated warehouse goods management, and analysis of database and the interface system. The automated warehouse management and control system realize the automation of warehouse management and directly, eventually to improve the comprehensive automation level of enterprises has a certain value.

Abstract: Recently, many countries have been pushing for a higher share of renewable energy sources, especially wind, in their generation mix. However, the intermittent and uncertain nature of wind power imposes a limit on the extent it can replace the conventional generation resources. In a high wind penetration scenario, the Battery Energy Storage System (BESS) offers a solution to the grid operation problems. The purpose of this paper is to evaluate the merits of price-based operation of BESS in a real-time market with high wind penetration using frequency-linked pricing. The authors propose a real-time market in which real-time prices are based on the grid frequency. A model for real-time price-based operation of a conventional generator and a BESS is presented. Simulations for different wind penetration scenarios are carried out on an isolated area test system. Wind speed sequence is generated using composite wind speed model. A simplified model of wind speed to power conversion is adopted to observe the impact of increase in wind power generation on the grid frequency and the real-time prices.

Abstract: This paper proposes a novel sliding-mode model reference adaptive system (MRAS) observers for speed observer in a sensorless controlled doubly fed induction generator (DFIG) aligned with the stator flux. In the strategy, two stator flux models with different structure are used. The stator flux voltage model without including rotor position item is used as reference model, and the stator flux current model including rotor position item as adjustable model. A slide-mode surface is formulated from the errors between the two models, and the rotor speed estimation can be obtained by a sliding mode algorithm. Meanwhile the one order inertial link is used to avoid suffering from integrator drift effects in voltage model. Simulation results confirm the validity of the approach.

Abstract: This paper explains and demonstrates how to construct a constant pressure water supply system with an integrated intelligent inverter controller (CPS-20B type) based on fuzzy control. This system can automatically adjust the mode of operation in accordance with different working conditons. The controller can choose the number of working pumps and change the motor speed to achieve constant pressure water supply. The PID regulator is set in the CPS-20B1 controller to adjust the output of the inverter, and the automatic regulating system is formed into a closed loop. The simulation results and practical application show that this system used in the water supply network can keep the water pressure stable. This system has been used in a number of industrial and civil water supply service since 2009, which improved efficiency and saved cost.

Abstract: In this paper the optimized design of ultrasonic metal welding transducer has been done by using the finite element analysis method and the Screwing torque test. The converter part, boost part and horn part are all taken into account here. The p-wave propagation on the face and s-wave on the flange are approved primely. With the binding force changes, the mechanical Q value of transducer changes also followed. Therefore the amplitude of the output energy will be affected. Through the experiment the optimal design of the Screwing torque output were achieved. Metal Ultrasonic welding has its own special requirements. And the mechanical vibration frequency of the transducer is set as 20 kHz here. At last phase and frequency characteristics of the transducer were measured with Impedance Analyzer Test.