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A transmitted optical fiber sensing system based on orthogonal demodulation algorithm is used for hydrogen detection in this paper. WO3/Pt fabricated by sol–gel method was used as sensing material. WO3 film reacts with hydrogen by the catalysis of Pt and refractive index of the sensing film changed, by measuring the transmitted optical power the concentration of hydrogen can be detected. Orthogonal demodulation algorithm was used to demodulate the weak transmitted optical intensity signals. Compared with the traditional ratio-type transmitted optical fiber hydrogen sensing system, the noise reduced by 28 times. The limit of detection is 495ppm and with good repeatability and stability. In order to improve the sensitivity of the system, three pieces of sensing film were used to increase the interaction length of the sensing material with hydrogen and the sensitivity increased by 2.592 times. With the orthogonal demodulated technique and multi pieces of sensing film, high sensitivity, fast response and low cost hydrogen sensing system was implemented and is very promising for the monitoring of hydrogen leakage in the field of hydrogen production, transportation, and storage.

In this paper, an active disturbance rejection control guidance law is proposed for the problem of unmanned aerial vehicle (UAV) collision avoidance. First, a linear time-varying collision avoidance model based on a collision cone is established. Then the active disturbance rejection control guidance law is designed to ensure the security of UAV collision avoidance. In addition, the stability of a nonlinear active disturbance rejection system with an extended state observer is proved by the circle criterion, and the stability conditions are used to design the guidance coefficients. A simulation system based on a six-degrees-of-freedom UAV model is used to demonstrate the performance of this guidance law. The results conclusively demonstrate that this method can achieve collision avoidance in the presence of sensor noise, an unknown acceleration of an obstacle, and wind disturbance. Moreover, the manoeuvring range of collision avoidance using this method is narrower than the collision avoidance method based on nonlinear dynamic inversion guidance.

Aiming at the identification and classification of radar radiation sources, this paper proposes a classification method based on the Convolutional Neural Network(CNN) for radar signal classification. Firstly, this paper sets the appropriate learning rate, batch size, iteration number, momentum and weight decay coefficient. Secondly, the time domain real part waveform signal is modeled and the network structure is selected for analysis. Finally, according to the spectrogram of the time domain waveform by Short Time Fourier Transform(STFT), design two different convolutional neural network models. The results show that the network learns more distinguishing feature representations and has better generalization capabilities after STFT. The Deep Learning of CNN has a greater advantage in extracting the feature representations in the spectrogram of the radar signal.

Track quality (TQ) evaluation of tactical data link is most crucial content in track processing, and is also the basis of tactical data link. In this paper, a new assessment method is presented to calculate the TQ. At first, TQ area equation defined in the U.S. Army tactical data link formatted message standard (TADIL) 6016B is introduced. Meanwhile, according to the educing and analyzing, this paper shows that the track quality in U.S. Army data link is defined according to the ellipse expression based on the distributing, and the TQ acreage value equals to the acreage of ellipse. Moreover, a new method of distance measurement on TQ value is proposed. At last, simulations show the affection of the geography location error, radar measurement error and extrapolation error on the TQ value.