Application of TSD tunnel seismic prediction system in karst area

TSD is one of the classical methods of tunnel seismic prediction based on higher accuracy multi-wave multi-component seismology.The working principle of the TSD and an application example of the TSD on tunnel prediction in Chongqing are introduced in this paper.This system has two ports for speed signal and acceleration signal,and the equipment is more portable and easy to use.According to the application results we can conclude that the TSD prediction system is accurate and it has the wide application prospect in tunnel seismic detection.

Application of ultrasonic CT method in nondestructive detection of interior defects in large scale concrete structural member of bridge

The ultrasonic computed tomography(USCT)method is derived from the basic principles of X-ray section scanning.This method records the arriving times of ultrasonic wave between the probes and the sources to calculate the elastic wave velocity values in the section using the arrival times.Through analyzed the distribution of elastic wave velocity in aim area,the information of the strength and the homogeneity of the investigated zone could be got indirectly.The authors introduced the operational principle of USCT and a practical case of using this method to detect the interior defects in large scale concrete structural member.Compared with other exploration methods,this method is more efficient and accurate.

Recent advances in functional fiber electronics

Rapid development ofwearable electronicswith various functionalities has stimulated the demand to construct functional fiber devices due to their merits of mechanical flexibility,weavability,miniaturization,and integrability.To this end,fiber components which can realize the functions of energy storage and conversion,actuating plus sensing have gained increasing concerns.Herein,we summarize the recent progress with respect to fiber material preparation,innovative structure design,and device performance in this review,also highlighting the possibility of integrated fiber electronics as an extension of application,the remaining challenges and future perspectives toward next-generation smart systems and to facilitate their commercialization.

Analyzing OAM mode purity in optical fibers with CNN-based deep learning

Inspired by recent rapid deep learning development,we present a convolutional-neural-network(CNN)-based algorithm to predict orbital angular momentum(OAM)mode purity in optical fibers using far-field patterns.It is found that this image-processing-based technique has an excellent ability in predicting the OAM mode purity,potentially eliminating the need of using bulk optic devices to project light into different polarization states in traditional methods.The excellent performance of our algorithm can be characterized by a prediction accuracy of 99.8%and correlation coefficient of 0.99994.Furthermore,the robustness of this technique against different sizes of testing sets and different phases between different fiber modes is also verified.Hence,such a technique has a great potential in simplifying the measuring process of OAM purity.

Experimental observation of topologically protected defect states in silicon waveguide arrays

Photonic waveguide arrays provide a simple and versatile platform for simulating conventional topological systems.Here,we investigate a novel one-dimensional(1D)topological band structure,a dimer chain,consisting of silicon waveguides with alternating self-coupling and inter-coupling.Coupled mode theory is used to study topological features of such a model.It is found that topological invariants of our proposed model are described by the global Berry phase instead of the Berry phase of the upper or lower energy band,which is commonly used in the1 D topological models such as the Su–Schrieffer–Heeger model.Next,we design an array configuration composed of two dimer patterns with different global Berry phases to realize the topologically protected waveguiding.The topologically protected propagation feature is simulated based on the finite-difference time-domain method and then observed in the experiment.Our results provide an in-depth understanding of the dynamics of the topological defect state in a 1D silicon waveguide array,and may provide different routes for on-chip lightwave shaping and routing.