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In this paper, a weak impulse signal detection method based on phase space reconstruction of chaotic time series and long-term and short-term memory neural network (LSTM) in the deep learning model is proposed. Reconstructing the phase space of chaotic signals can effectively extract the chaotic information in the sequence, and constructing LSTM neural network can effectively distinguish the signal points from the non-signal points to achieve better detection results. When detecting the weak pulse signal in Lorenz chaotic system and Rossler chaotic system, the model has high detection accuracy and can still maintain the detection performance when the signal-to-noise ratio is low. This paper compares it with other machine learning models and deep learning models, such as Support Vector Machine (SVM), Recurrent Neural Network (RNN), Extreme Learning Machine (ELM), and so on. The results show that the detection accuracy of this model is higher than other comparable models under different signal-to-noise ratios and has strong detection performance. In addition, the weak pulse signal in the sunspot sequence is detected, and the fault signal in the rolling bearing is diagnosed. These results show that this model can accurately detect the weak pulse signal in the chaotic background when the signal-to-noise ratio is low and is suitable for dealing with the weak signal detection problem in the chaotic background in real life and the fault diagnosis problem in the engineering application field. This not only reduces the detection threshold of weak signal detection but also widens the application field of weak signal detection. [ABSTRACT FROM AUTHOR]

Leptographium procerum (Ophiostomatales, Ascomycota) is a well-known fungal associate of pine root-infesting bark beetles and weevils, occurring in several countries of the world. The fungus is not a primary pathogen but has been associated with white pine root decline in the USA and with serious damage caused by the introduced red turpentine beetle (RTB) Dendroctonus valens in China. Several species closely related to L. procerum have been described during the past decade. The aim of this study was to reevaluate species boundaries in the L. procerum complex using multigene phylogenetic analyses and morphological comparisons. Phylogenetic analyses of seven gene regions (ITS2-LSU, actin, β-tubulin, calmodulin, translation elongation factor 1-α, and the mating type genes MAT1- 1- 3 and MAT1- 2- 1) distinguished between nine species in the complex. These included L. procerum, L. bhutanense, L. gracile, L. profanum, L. pini- densiflorae, L. sibiricum, L. sinoprocerum, as well as two new species described here as Leptographium sinense sp. nov. from Hylobitelus xiaoi on Pinus elliottii in China, and Leptographium longiconidiophorum sp. nov. from Pinus densiflora in Japan. Leptographium latens is reduced to synonymy with L. gracile, and an epitype is designated for L. procerum, because a living culture associated with the holotype of L. procerum did not exist. Amplification patterns of the mating type genes suggest that all known species in the L. procerum complex are heterothallic, although sexual states have not been observed for any of the species. The results also suggest that Eastern Asia is most probably the centre of species diversity for the L. procerum complex. [ABSTRACT FROM AUTHOR]