A mutual coupling reduction antenna design for WLAN MIMO application is proposed. The proposed antenna array consists of two rectangular patch antennas, six parallel metal strips, a single substrate layer, and common ground plane. About −42 dB mutual coupling is achieved at the 5.8 GHz resonant frequency. Both simulation and measurement results confirm improvements in mutual coupling at about 30 dB when compared with those without metal strips. The radiation patterns are almost unaffected by adding these metal strips in the proposed antenna.

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This paper summarizes the basic module of power transform circuit through the research of the various inverter circuits, and gains the essence of power transform system. It analyzes the advantages and disadvantages through the research of voltage-source inverter and current-source inverter, and points out the characteristics of the circuit. The circuits are explained with the essence of power transform system. The unique characteristics different from other inverter of the Zsource inverter are analyzed. At last, the modules of a power electronic circuit which contains inductive module and switch module as well as diode module are proposed by the comparison of the differences among the three inverter circuits.

This paper is concerned with the design and implementation of a ZigBee based wireless sensor and actuator networks, which has been applied in our service robot intelligent space successfully. Firstly, an overview of ZigBee protocol is given, and then the design and implementation of hardware module and software stack of ZigBee based wireless sensor and actuator networks are addressed in detail. Some representative devices are described, including environmental sensors for environmental perception, home devices controllers for device control, IMU module for abnormal behaviors detection, locating system for node localization and laser robot control for service robot navigation. Application example is described to demonstrate how the devices in ZigBee based wireless sensor and actuator networks to provide service cooperatively. Finally, we conclude this paper and discuss the future directions.

Gabor transform suitable for time-frequency analysis and good for filtering non-stationary signals. The threshold of the Gabor transform filter is a key factor for the filter’s effectiveness. The popularly used threshold obtained by linear method is not suitable for non-stationary signals with low signal to noise ratio (SNR) because, it cannot separate the expansion coefficients of noise and useful signals. In this paper, a novel method to identify Gabor transform filter’s threshold based on initial highest inter-cluster distance probability is proposed. Simulation experiments have been carried out under several conditions. The experimental results show that the proposed threshold is highly suitable, especially when the signal’s SNR is very low and the filter output is very consistent to the real original signal and keeps no pseudo signal in zero regions.