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In this paper, a quantitative detection method of the weak ultrasonic guided wave (UGW) signal based on information entropy of the Duffing chaotic system is proposed. It can simultaneously identify the location and size of small defects in pipelines. First, by adjusting the driving force amplitude of the Duffing system, the system is in a critical state from period to chaos. When the weak UGW is added on the driving force, the state of the Duffing system will change. It can be used to detect weak signal. To realize the quantitative detection of UGW, a method based on information entropy is presented in this paper. By analyzing the influence of UGW on the driving force amplitude of the Duffing equation, a sensitive damage index is constructed to indicate the signal strength. Furthermore, a time-moving window function is introduced. By scanning the recording signal, the defect location can be identified using the damage index. The experimental studies show that the proposed method is validity for detecting small defects in pipeline, and simultaneously identify the size and location of the defects. This method has a strong noise immunity and significantly improves the sensitivity of small defects detection in pipelines. Highlights: A method to calculate the information entropy of Duffing system is proposed. A method for detecting small defects in pipe is proposed based on the sensitive dependence on initial conditions and information entropy of chaotic system. The method is successfully used to detect small defect detection in a pipe. [ABSTRACT FROM AUTHOR]

Herein, a new strategy is proposed for achieving dynamic chiral controls in self-assembly systems of plasmonic nanorods based on temperature-modulation. Via enlarging Au{100} side facets of Au nanorod (AuNR) building block and changing surface ligand from often-used cetyltrimethylammonium bromide (CTAB) to cetylpyridinium chloride (CPC), inversion of chiroptical signal in side-by-side (SS) oligomers is realized. Under the guide of chiral cysteine (Cys), Au{100} side facet-linked SS rods twist in the opposite direction compared with Au{110} side facet-linked counterparts. At high CPC concentration, by controlling the incubation temperature of chiral Cys, the dominant twist mode can be regulated. Finite-difference time-domain (FDTD) simulations indicate the key role of the twisting dihedral angle of the oligomers in driving chiral signal inversion. At low CPC concentration, a temperature-sensitive chiral switching is observed owing to the conformation change of the CPC ligand layer. The temperature-modulated chiral responses are based on the interactions of chiral molecules, achiral surface ligands, and exposed facets of the building block. The rich dynamic tunability of chiroptical responses of plasmonic assemblies may find applications in stimulus-responsive nanodevices. [ABSTRACT FROM AUTHOR]

We propose an interactive analytical system for exploring and interpreting non-linear projections. Although non-linear projections are widely used in disclosing complex structures in high-dimensional analysis, there is a strong need to interpret them due to their inherent complexity and weak interpretability. In the machine learning and visualization communities, it is inspiring to use local linear models to fit and interpret non-linear models. Regarding non-linear projections, there are research gaps in both generation and exploration of linear fitting segments. To fill this gap, we propose an optimization algorithm to partition a non-linear projection into linear segments according to the feature of local affine transformations. We then construct a hierarchy of linear segments and conjunct hierarchical visualizations to support a coarse-to-fine exploration. After that, we design and implement a visual interface that integrates the proposed algorithms and a suite of visual tools. Three case studies demonstrate that the proposed approach facilitates the interpretation of non-linear projections. [ABSTRACT FROM AUTHOR]