This paper introduces the denoising theory based on wavelet threshold ,and it presents a new threshold function based on traditional soft and hard threshold function and weighted threshold function。Simulation results show that:the new threshold function can be more effective to eliminate noise and restore image.
Capacitor tester Agilent GPIB interface provides only and can not be directly related to PLC data transmission problems, the paper-based automatic test system designed GPIB interface using a IPC, through the GPIB interface card with the capacitance tester data collection, in addition, the application of the digital I / O card for the data exchange between the PLC and then form an automatic test system, not only greatly improves the efficiency and accuracy of the test, the test also facilitates data management system for late data analysis system has laid a good foundation.
Ensemble Empirical Mode Decomposition (EEMD) can overcome the mode mixing problem in Empirical Mode Decomposition (EMD) effectively. The Hilbert-Huang transform still exists end effect in applications, in order to improve the end effect, this paper put forward a method of fault feature extraction based on improved EEMD and Hilbert transform which combines support vector regression (SVR) machine with mirror extension to continue the signal. The analysis on simulation experiments results show that the method can restrain the end effect effectively, get a more accurate instantaneous frequency and instantaneous amplitude.
A hybrid fiber optically powered current transformer with the Hall element is studied and developed in this paper. The sensing probe is the zero-flux current transformer which is based on Hall Effect. The main current can be insulated from the measurement circuit by use of Hall current transformer. Due to the broad bandwidth characteristics and the high linearity between the Hall potential and measured magnetic flux density and the high sensitivity of the Hall current transformer, any changes in the excitation current can be accurately detected without distortion. The three-dimensional model of the Hall current transformer is set up by use of ANSYS software in this paper. The magnetic flux density in the opening air-gap is calculated by nonlinear magnetic analysis method of the three-dimensional finite element. Experimental data shows that the calculation method and results are reliable. At the same time, high power laser power supply is adopted to drive the electronic devices in high potential side, and the reliable insulation between the high potential and low potential is achieved by optical fibers. So the accuracy of this measurement system can be ensured.
The IEEE1451.4 is a new standard for plug and play sensors.The standard defines a mechanism for self-description and self-indentification for the traditional analog sensors.The mechanism reduce the time for configuration and diagnosis greatly.Introduce IEEE1451.4 and IEEE1451 other standards.The structure and model of the IEEE1451.4 sensors are analyzed.TEDS(Transducer Electronic Data Sheet) that contains the information of sensors and MMI(Mixed-Mode Interface) that transfers both digital signals and analog signals are carried on reseach in detail.
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