We propose a substructure approach that allows for the local damage detection of a shear structure. This method requires only three sensors to identify localized damage in any story of a shear structure building. A substructure approach was used in this method to divide a complete structure into several substructures in order to significantly reduce the number of unknown parameters for each substructure so that damage detection processes can be independently conducted on each substructure. Thus, our method is suitable for use in a parallel and distributed damage detection system. Simulations and experiments on five-story buildings were conducted to test the feasibility of our proposed method.

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In this paper, an all-optical quadrature phase shift keying (QPSK) phase regeneration scheme using vector phase sensitive amplification (PSA) is proposed, analyzed, and simulated. Compared with the conventional scalar PSA scheme, the vector superposition of harmonics makes it easy to obtain high gain extinction ratio (GER) with low pump powers. A subsequent phase-preserving amplitude regenerating device is also introduced to achieve full-quadrature regeneration of signal without phase conjugation and frequency conversion. In addition to the theoretical analysis of the implementation principle, a series of simulation results' analysis, including comparison with traditional scheme and regeneration performance assessment, is also included. The results show that undesired harmonics are greatly reduced by nearly 40 dB, and high GERs are available independent of input power. What is more, various levels of phase and amplitude noise can be effectively compressed for 10-Gbd QPSK signal. The regeneration system also reduces the signal bit error rate and gets 2-dB receiver optical signal noise ratio (OSNR) improvements at 13-dB OSNR input, which has potential applications in enhancing transmission distance in the future optical communication network.INDEX TERMS All-optical signal regeneration, optical fiber communication, optical signal processing, optical polarization, phase sensitive amplification, quadrature phase shift keying.

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A local damage detection method for shear structure based on substructure approach and sub-time series superposition is proposed, which is promising for application in parallel and distributed damage detection systems. This method requires only three sensors to identify localized damage in any story of a building and it doesnt require constructing the structure models. A substructure method was used in this method to divide a complete structure into several substructures. Each substructure has a considerably smaller number of degrees of freedom (DOFs) which makes fewer requirements on the computing power of the data processing system. The algorithm is simple, which involves only algebra calculation and does not need any iterative computation. Moreover the damage detection process can be independently conducted on each substructure. Thus, this method is easy, efficient and suitable for being embedded into parallel and distributed damage detection systems. To better assess the performance of the method proposed above, experimental verification of the proposed approach has been conducted, which shows the proposed method works quite well and stably.