Application Of Explosive Detection With Sequential Probability Ratio Test And Wavelet Transform

The detection of dangerous goods has become an important issue in the field of public safety.The strengthening the detection of dangerous goods is an important means to ensure the safety of people's lives and property in public places,such as airports and stations.More importantly,the dangerous goods hidden in the luggage are timely and accurate found and its type is predicted.Scholars have developed a number of explosives detection methods with the rapid development of science and technology.The neutron detection methods have been popular in recent years because of their strong penetrating ability and their ability to react with nuclei to determine the elemental content of explosives.According to the detection requirements of explosives,we have designed and developed a portable explosives detection device based on the tagged neutron method.After introducing the principle of explosive detection,an explosives detection device has been designed from detectors,neutron sources,shields and so on.The device can be placed on a movable flatbed to achieve the portable features.Energy spectra of different substances were obtained by measuring the samples TNT and ammonium nitrate,milk,dry milk powder using portable explosives detection device.The energy spectra obtained by the tagged method greatly reduces the background and improves the signal-to-noise ratio.This method has certain practical significance and application value in the detection of dangerous goods.In the process of analyzing and processing energy spectrum,wavelet analysis is used to denoise the energy spectrum.The wavelet analysis can carry on the signal analysis in time domain and frequency domain at the same time,which it can effectively realize the signal denoising.The different wavelet basis functions are used to denoise for gamma spectrum.The denoising results of different basis functions are compared to select a better basis function.The traditional method of distinguishing explosives is based on the content of C,H,O,and N elements,but this method can not better be judged when the explosives are hidden in daily products such as milk powder and washing powder due to great interference.This article introduces sequential probability ratio test method to distinguish explosives.The SPRT method principle and the explosive detection process are described in this article.The SPRT is used to analyze and calculate the energy spectrum obtained by the system.The validity of the SPRT algorithm was verified by identifying and detecting both the non-explosive and explosive states.The results show that SPRT can correctly distinguish between explosives and organics,and greatly reduce the measurement time.SPRT has great application value and significance for explosives detection.