Abstract: Aim at the non-stationary and time-variation characteristic of the gear-box fault signal, proposing a condition identify method for gear-box based on EMD and NN. Take the vibrating signal of case as the analysis object, firstly, deal the signal with EMD, extract the IMFs’ energy moment as eigenvector, through neural network based on L-M optimization algorithm to identify gear-box fault. The result of testing certain armored vehicle reveals that method can identify a variety of conditions of gear-box effectively, and provides a availability intelligence fault diagnosis method for gear-box.
Abstract: Energy is an important material foundation for developing the national economy and improving human living standards. We discussed the energy-saving principle of urban water supply system variable frequency pumping by analyzing the urban water supply and water pumping station curves, further studied the best speed and flow adjustment range of the Urban Water Supply Systems Variable Speed Pump, from both economic and efficient operation of pumps taken into account to determine the best number of the speed pump sets, which can be referenced for the design of urban water supply system variable frequency speed pump station.
Abstract: The tube leakage in the large power station boiler is the main reason for unplanned outage of power units. So how to prevent and control the leakage accident has become an important part of ensuring the safe operation of power grid. Sound spectrum analysis is the most commonly used detection method. At the top of the boiler, the temperature is high, and sometimes the positive pressure produced inside the boiler will make ordinary audio sensors particularly easily damaged. This paper designs a system of high temperature resistance fiber optic audio sensor and acoustic resonator. It can determine the parameter of fiber optic audio sensor, and double the leakage noise signal through the design of acoustic resonators. According to the experimental test results and theory, this system can effectively test leakage signal inside the boiler tube, and provide a new idea for leakage detection.
Abstract: A new structure of amorphous/ polycrystalline silicon heterojunction solar cells is reported. For a-Si (n+)/poly-Si (p)/poly-Si(p+) structure, the concentration, thickness, and the defect states of BSF are discussed. It is shown that the cell performance improves with thickness between 10-15nm, concentration is of the order of 1E19cm-3, the maximum efficiency up to 20.45%.
Abstract: This paper proposes a robust position controller for a precision mechatronics system, based on the quantitative feedback theory (QFT), to achieve high accuarcy and consistent tracking performance even in presence of considerable structural dynamic uncertainties and external disturbances. Tthe dynamic characteristic of precision mechatronics system is experimentally identified with close-looped identification method, taking account of system uncertainties, and then a QFT controller is designed. Simulations are carried out to validate the efficience and effectiveness of the proposed controller.
Abstract: In this paper, the advantage of virtual instrument technology is analyzed, and vibration-monitoring system of hydropower unit based on virtual instrument technology was developed combining the requirement of vibration monitoring. The design idea on hardware configuration and functions of each software system module of the system are introduced. The test experiments are made in the laboratory. Experiment results show that the system developed in this paper can realize the function of real-time sampling of the data, monitoring, analyzing, testing and remote diagnosis of the hydraulic vibration.
Abstract: A fuzzy self-correction controller based on DSP (TMS320LF240) micro-controller was designed to solve the problem that traditional controller can’t meet the random disturbance parameters of reluctance motor having notable nonlinear. Parameters could be automatically adjusted and response is rapid. According to the demand that two windings provide electric power at the same time for switched reluctance motor (SR motor), the system adopted Mamdani model with two inputs, MAXMIN barycenter technique was used for judging manner. Fuzzy research table and driving software were designed. Experiment results with a 5.5KW SR motor illustrated that the four phases SRD with fuzzy control technology proposed in this paper has excellent driving character.
Abstract: Wavelet neural network based adaptive robust output tracking control approach is proposed for a class of MIMO nonlinear systems with unknown nonlinearities in this paper. A wavelet network is constructed as an alternative to a neural network to approximate unknown nonlinearities of the classes of systems. The proposed WNN adaptive law is used to compensate the dynamic inverse errors of the classes of systems. The robust control law is designed to attenuate the effects of approximate errors and external disturbances. It is proved that the controller proposed can guarantee that all the signals in the closed-loop control system are uniformly ultimately bounded (UUB) in the sense of Lyapunov. In the end, a simulation example is presented to illustrate the effectiveness and the applicability of the suggested method.
Abstract: Although many converter control circuits have been integrated digitally, digital circuits are limited by the sampling rate, the processor frequency and other factors, and the response speed is slower than the analog circuits. In this paper, the combination of PI regulator and hysteresis loop PWM control is adopted to set up a DC/DC analog control circuit. The simulations and experiments show that the design achieves DC/DC bi-directional conversion and phase-shifting output. The DC/DC transformation function has been realized safely and reliably.
Abstract: Now, security of network is threaten from double layers inside and outside network, the inherent defect of firewall technology makes the intrusion detection and network traffic analysis as the main means of defense, aiding firewall. Now network intrusion detection have problem of higher false alarm rate, we apply the data warehouse and the data mining in intrusion detection and the technology of network traffic monitoring and analysis, propose a new model of intrusion detection based on the data warehouse and the data mining. The experimental result indicates this model can find effectively many kinds behavior of network intrusion and have higher intelligence and environment accommodation.