Applied Mechanics and Materials Vols. 303-306

Abstract: Spin-coating films of Lead(II) tetrakis(4-cumylphenoxy) phthalocyanine (4-PbPc) were prepared and characterized by FT-IR and UV-vis spectra. The results show that the ideal different thickness spin-coating films of 4-PbPc are fabricated by different spin-coating concentration. The response of the films was investigated with respect to NH3 at room temperature. Moreover, the response and recovery properties and the effect of the film thickness on gas sensing performance are also discussed. The results indicate that the films display a high and fast response and good reversibility to NH3 and the 4-PbPc spin-coating films which could be explored as an NH3 sensor at room temperature.

Abstract: A three layer sandwich beam with an aluminum face sheet and a magnetorheological elastomer (MRE) core was fabricated. The transverse motion equations of MRE cantilever sandwich beam under non-homogeneous magnetic fields were derived with the fine Mead-Markus model, and the first natural frequency of the beam were calculated. Meanwhile, the first natural frequency of the beam was also simulated using ANSYS software. The numerical simulations accorded with theoretical results in general. The results are expected to provide guidance to develop broadband vibration isolation devices for railways and rolling stock.

Abstract: We propose and demonstrate an optical fiber acoustic sensor based on air backing mandrel type fiber optic hydrophone. This novel approach to sensing sounds in the air has not been utilized before and has the advantage that the sensor doesn’t need electric power supply when it is working. To prove the feasibility of such an optical fiber acoustic sensor, we make a model and set up experiment to get the acoustic waves response curve in frequency. Because of its simple mechanical structure, the sensor is robust and shows a good application prospect.

Abstract: An optical fiber sensor based evanescent absorption spectroscopy in the infrared range for the quantitative determination of H2O content in D2O has been evaluated. The coiled optical fiber sensor base on evanescent absorption spectroscopy has been investigated to monitor H2O concentration in D2O. The classical least square model has been utilized to build the calibration model and predict the H2O concentrations. The predicted H2O concentration in D2O is acceptably accurate and susceptible. The work demonstrates that the coiled fiber-optic sensor based on evanescent absorption spectroscopy is a feasible analytical technique for prediction of the low-level H2O content during deuterium oxide distillation in on-line and remote situation

Abstract: Interference Fiber Optic Gyroscope (IFOG) is the mainstream Interferometric Fiber Optic Gyroscope (IFOG) is the mainstream optic inertial sensor products of rotation measurement in nowadays. However, short time migration as well as long time bias had been impacting IFOG for the first day it invented. For a better operation of orthogonal demodulation algorithm, which we proposed before had demonstrated an ability of suppressing the noise in IFOG. This article firstly concerning about the initial phase in the orthogonal demodulation of IFOG. Through posteriori estimation we achieved the balance orthogonal demodulation. Secondly, we place the 2 orthogonal channel data obtained from the IFOG, as reference signal for each other into an adaptive filter module, based on the LMS principle, obtaining a real-time improvement of short time migration and long time stability.

Abstract: In trenchless detection of underground pipelines, a method has been introduced which employs Fiber Bragg Grating (FBG) sensors to detect curvatures of the pipeline at discrete points and reconstructs the spatial trajectory of the pipeline by means of a newly developed approach. In measuring the pipeline curvature, the FBG sensor may be twisted besides sustaining bending deformation. This paper proposes a new algorithm for curvature calculation at discrete points, considering both overall revolving and partial twisting of the FBG sensors in order to enhance the curve fitting accuracy. Simulation results verify the effectiveness of the method.

Abstract: The effects of Raman slow-light on room-temperature single-mode optical fiber sensors are examined by extracting the Raman pulse-delay terms from extended nonlinear Schrodinger equation (NLSE). Numerical study shows that pulse parameters such as pulse position, frequency chirp, and envelope distortion may be greatly affected by slow light. We demonstrate a method based on pump power adjustment for compensating the slow light induced impairment.

Abstract: In this paper, the influence of the Q point on the DEFPI fiber-optic sensors is comprehensively analyses. For a DEFPI fiber-optic sensor, the output signals vary with the different position of the operational point regarding to the same applied pressure. The optimal operational point is in the middle position of the fringe linear scope. In addition, we present a novel structure sensor to guarantee the stableness of the Q point.

Abstract: Optical compensation is studied for suppressing polarization nonreciprocity (PN) induced errors in interferometric fiber-optic gyroscopes (IFOG). In convention IFOGs, a polarizer is necessarily used, and only one polarization is used for interference in order to achieve low PN error. Differently, we propose a new approach for using two polarizations simultaneously in the IFOG. PN error can be effectively suppressing by optical compensation between the two detected signals. Both simulation and experiment are presented, which shows that PN errors are effectively reduced by optical compensation. This new approach paves the way for low drift IFOGs with no polarizer.

Abstract: Based on the fiber waveguide theory and the transfer matrix method,Research on the reflection spectrum of Gaussian apodized FBG which cladding were completely corroded under uneven medium.During the stimulation process,consider high refractive-index(1.43-1.45) area and low refravtive area(1.33-1.36) respectively.At the same time,suppose the uneven SRI in different linear function distributions.The stimulation result shows the Gussian apodized FBG’s spectrum bandwidth,spectrum intensity depends on the SRI along the grating axial linear distribution gradient.As SRI gradient increases,the gradient sensitivity of high refractive index area and low refractive index area are nm.mm/riu and nm.mm/riu respectively.The results have a definite significance of Gaussian apodized FBG for sensing technology used in biochemical of uneven medium measurement.