Research And Implementation Of Fast Detection Algorithms For Weak Nuclear Pulse Signals

With the continuous development of nuclear technology,nuclear energy has been widely used in various fields of industrial production,the number of radioactive sources is increasing,which puts forward higher requirements for the detection and control technology in the process of storage and transportation of radioactive sources.Therefore,it is of great significance to study the fast detection method of weak nuclear pulse signal and improve the accuracy of nuclide recognition for the supervision and control of radioactive sources.In the process of nuclear pulse signal detection,the weak nuclear pulse signal output by the gamma detector is easily interfered or even submerged due to the existence of environmental background noise and circuit noise.In this paper,aim at the problem that weak nuclear pulse signal is difficult to detect under the background of noise,the time-domain features of weak nuclear pulse signal are extracted by sparse representation method,and the over-complete dictionary of nuclear pulse signal is constructed.Then,the atomic of reconstruction signal is selected from the over-complete dictionary by tracking algorithm and the signal-to-noise ratio of weak nuclear pulse signal is improve.The specific research content is as follows:(1)Research basic principles of weak nuclear pulse signal detection,design and construct weak nuclear pulse signal detection system and analyze the index parameters of each module in detection system.Weak nuclear pulse signal is obtained by measuring experiments,the amplitude information and phase information of the signal in the time domain is analyzed.Based on the mathematical model of nuclear pulse signal,using simulation signal and measured signal to provide data for experiment of verify the effect of algorithm proposed in this paper.(2)Aiming at the denoising problem of weak nuclear pulse signal,the detection method of weak nuclear pulse signal based on sparse theory is studied.Using singular value decomposition to extract time-domain information of nuclear pulse signals and build an over-complete dictionary.Then,using the orthogonal matching pursuit algorithm to find sparse solution,complete the detection of weak nuclear pulse signal.Using sparse solution to select the optimum number of atoms to reconstruct the true nuclear pulse signal,so as to complete the detection of weak nuclear pulse signal.(3)In order to solve the problem of large amount of data and high computational complexity of sparse algorithm for nuclear pulse signal,propose a method based on detector for preprocessing nuclear pulse signal to screen useful nuclear pulse signal.Improved sparse algorithm based on the idea of concurrent computation,presented a fast method for the detection of weak nuclear pulse.The simulation and experimental results verify the effectiveness of the proposed methods.Finally,using laboratory-built experimental platform to carry out the measured experiment.By changing the velocity and shielding state of the radiation source,research the influence of different detection conditions on the nuclear pulse signal,and the effectiveness of the proposed method was verified.