Advanced Materials Research Vol. 711

Abstract: In this paper a new type shield cutter wear detection method based on ultrasonic thickness measurement theory was presented. Its working principle was introduced. Its hardware and software were designed. Compared with the existing detection methods, the new method is more accurate and more intuitive, and the method can also provide technical support for the project very well.

Abstract: Combined with engineering conditions of the III-level south roadway of Yangzhuang Mine, the deformation of surrounding rock and mechanical characteristics of support structure is analyzed by FLAC3D numerical simulation when the roadway is supported by CFSTS support program . The results shows that: For the weak mudstone surrounding rock and complex geological conditions, the deformation of surrounding rock is fast, large and unsymmetrical deformation, the bolt-net-shotcrete support is difficult to maintain the roadway stability. the CFSTS used Φ219 ×8mm steel tube filled with C50 core concrete, which provides powerful supporting force combined with other roadway support ways and restrict surrounding rock to the roadway space. By FLAC3D simulation analysis shows, the deformation of surrounding rock is small and support structure is mad good use and keep work, which can maintain the stability of roadway.

Abstract: The use of recycled aggregates in concrete has increased in recent decades. Increasing scarcity of natural aggregates and the growing ecological importance promote this evolution. The first test section in Belgium of a two-layer continuously reinforced concrete pavement (CRCP) with recycled aggregates in the substrate layer was built on the highway E34/N49 in 2007. Horizontal cracking at the level of the reinforcement showed up after only a few years. This is a problem which was never seen before in CRCP and was probably due to the use of recycled aggregates. Therefore it is important to understand the impact of recycled aggregates on concrete. Recycled aggregates are a two-component material consisting of natural aggregates and adhering mortar. The adhering mortar is more porous than the rock particles which insures a higher water absorption and lower density. In addition, they have a lower abrasion loss in the Los Angeles-test and less resistance against weather and temperature changes. This is due to, respectively, the less strong mortar content, and the large pores of recycled granulates. A first cause of horizontal cracking can be found in the results of high drying shrinkage, high creep and low modulus of elasticity. These properties insure larger tensions in the concrete layer. In combination with a lower tensile strength it is a possible cause for the horizontal cracking. In addition, the paper reports on laboratory testing concerning the properties of concrete with recycled aggregates and discusses an alternative method to determine the concrete mixture which takes the influence of the adhering mortar into account.

Abstract: In this paper,a layer-wise theory is used to analyze the natural frequency and vibration modal of the composite laminated plate. Layer-wise theory assumes that displacement is continue through thickness direction and has good accuracy to analyze free vibration. The frequency and vibration modal are acquired while building the equation of motion according to layer-wise theory. Through comparing layer-wise theory and other theories, numerical results show that layer-wise theory is credible to analyze composite laminated plate. At the same time, experiment is used in this paper to acquire the natural frequencies and vibration modal of a simply supported composite laminated plate. Lastly, combination of the theory method and experiment method canprobably predict the natural frequencies and vibration modal.

Abstract: Certain error exists in the data collected from multi-sensor network, which is caused by the external interference and defect of sensors. Thus, data fusion algorithm is applied in such monitoring to improve the reliability. In this paper, we propose a heterogeneous sensor data fusion algorithm for temperature monitoring in carbon fiber carbonization process. Through an improved adaptive weighting algorithm and iteration algorithm based on the average value, data from heterogeneous sensors are merged to obtain data closer to the real values. The feasibility of the method is verified in experiment.

Abstract: This paper proposes a voltage-reactive power optimization, which is an integrated system based on centralized optimization and distributed control, to confine the action numbers of control devices. The system includes VQC (voltage and reactive power control system) and the optimal power flow calculation in the master station. By using the fractal theory, the original data in the range of nonperiodic cycles are divided into several time-intervals. After this processing, the optimal points are obtained by optimal power flow in every segment. Based on the load fluctuation rate, in every period, the voltage / reactive power limits of nine area figure are set. As the load fluctuation rates changed in every segment, voltage / reactive power limits are different. And the tap changers and switchable capacitor banks are regulated according to each upper/lower limits and the optimal points. Furthermore, correctness and effectiveness of the proposed method have been confirmed. And the simulation results show that it not only reduces power losses but also restricts the action numbers of control device.

Abstract: Multi-axial mechanical testing with servo-hydraulic cylinders is used as essential tool within the development and manufacturing process of mechanical components and structures, enabling the experimental validation of the fatigue behavior and related mechanical endurance limits. In this paper we derive the analytical model of servo-hydraulic cylinders feasible for fatigue tests to enable the incorporation of the derived actuator dynamics within multi-axis test control strategies. Our derived cylinder model includes the test cylinder with attached position sensor, and a state-of-the-art servo valve. Based on the obtained cylinder dynamics we propose a simplification to a low order cylinder model, highly desirable for reducing overall system complexity in order to develop ease-of-use controllers of high performance for multi-dimensional test rigs. We compare the simulated output of the derived actuator models with the measured data from a real world test cylinder system. The obtained results show that the obtained system model accurately describes the dynamic properties of a real world test cylinder, and furthermore validates the process of model simplification for efficient control of such cylinders as part of low-bandwidth multi input multi output servo-hydraulic test systems.

Abstract: A NURBS surface tool trajectory planning method of engraving robot is proposed. The calculation algorithm including NURBS surface tool trajectory, cutting point and effective cutting radius of end milling cutter and inverse kinematics transform is discussed in detail using Taylor and coordinate transformation method. It is the foundation to further applied to the engraving robot tool trajectory planning or off-line programming.

Abstract: In this paper, according to the induction motor in rotating coordinate system mathematical model, established based on rotor flux oriented vector control model and realized flux linkage and torque decoupling. In order to solve the current high coupling, designed the sliding mode variable structure control algorithm of current controller. Based on the sliding mode variable structure control algorithm achievable conditions and Lyapunov stability theorem, proved that the sliding mode of accessibility and stability, determined the sliding model parameters. The simulation results show that the sliding mode variable structure control of induction motor vector control system, can reduce the torque ripple and the speed overshoot and improve the system parameter perturbation and external disturbance signal robustness.

Abstract: In this paper we develop a robust controller based on sliding mode, neural network and fuzzy logic for the control of a class of under-actuated systems. The stability of the proposed controller is proved with the Lyapunov function method. Simulation results are made on an inverted pendulum.