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The purpose of this paper is to introduce a novel intensity-modulated fiber optic sensor for real-time intrusion detection using a fiber-optic microbend sensor and an optical time-domain reflectometer (OTDR).

The proposed system is tested using different scenarios using person/car as intruders. Experiments are conducted in the lab and in the field. In the beginning, the OTDR trace is obtained and recorded as a reference signal without intrusion events. The second step is to capture the OTDR trace with intrusion events in one or multiple sectors. This measured signal is then compared to the reference signal and processed by matrix laboratory to determine the intruded sector. Information of the intrusion is displayed on an interactive screen implemented by Visual basic. The deformer is designed and implemented using SOLIDWORKS three-dimensional computer aided design Software.

The system is tested for intrusions by performing two experiments. The first experiment is performed for both persons (>50 kg) in the lab and cars in an open field with a car moving at 60 km/h using two optical fiber sectors of lengths 200 and 500 m. For test purposes, the deformer length used in the experiment is 2 m. The used signal processing technique in the first experiment has some limitations and its accuracy is 70% after measuring and recording 100 observations. To overcome these limitations, a second experiment with another technique of signal processing is performed.

The system can perfectly display consecutive intrusions of the sectors, but in case of simultaneous intrusions of different sectors, which is difficult to take place in real situations, there will be the ambiguity of the number of intruders and the intruded sector. This will be addressed in future work. Suitable and stable laser power is required to get a suitable level of backscattered power. Optimization of the deformer is required to enhance the sensitivity and reliability of the sensor.

The proposed work enables us to benefit from the ease of implementation and the reduced cost of the intensity-modulated fiber optic sensors because it overcomes the constraints that prevent using the intensity-modulated fiber optic sensors for intrusion detection.

The proposed system is the first time long-range intensity-modulated fiber optic sensor for intrusion detection.

The purpose of this paper is to theoretically analyze and experimentally demonstrate the investigation on and optimization of a distributed optical fiber sensor based on phase-sensitive optical time domain reflectometer (F-OTDR) for disturbance detection.

The F-OTDR system is investigated and optimized in two aspects: the hardware parameter and the interrogation scheme.

Based on the optimized hardware and the new interrogation scheme, the performances of the F-OTDR system have been improved greatly, compared with conventional F-OTDR system. A location accuracy of 2 m and a signal-to-noise ratio (SNR) of 16 dB have been achieved under a spatial resolution of 8 m. On the other hand, four disturbances at four different locations have been detected and located simultaneously, which is the most effective detection system with the maximum detection capability reported to date, to the best of the authors’ knowledge.

Four disturbances at four different locations have been detected and located simultaneously, which is the most effective detection system with the maximum detection capability reported to date, to the best of the authors’ knowledge. With same hardware conditions, more existing disturbances can be detected by using the new interrogation scheme, which is helpful to reduce the miss report of disturbance.

Distributed temperature sensing (DTS) can identify locations and factors of seepage in embankments. Inspired by the classical transient hot-wire method (THW), the focus of this paper is to investigate the feasibility and propose a calibrated method of seepage velocity monitoring using the optical fiber DTS.

According to the definition and the measurement of thermal conductivity, the nominal thermal conductivity, which comprehensively reflects the influence of heat transfer and seepage factors, is proposed and the corresponding solution is also derived. Then, a flume testing platform of an embankment seepage monitoring system composed of the optical fiber heat-up subsystem, the seepage controlling subsystem and the optical fiber DTS subsystem is designed and built. Meanwhile, the data processing and assistant analysis subsystem (DPAAS) is also developed to effectively acquire the experimental data of concerned locations and obtain the corresponding nominal thermal conductivity under various seepage conditions. Based on these setups, a series of laboratory flume experiments are carried out under controlled velocities and heating powers.

The plots of recorded temperature rise versus natural logarithm of time allow the calculation of nominal thermal conductivities, and then the seepage velocity monitoring model particular to the experimental setup is successfully established with satisfactory precision.

Considering the complexity of water flow in embankments, a seepage flume that matches the natural system, allowing for larger experimental model scales, various water temperatures, various engineering materials and a wider range of seepage velocities, should be investigated in future.

The combined THW and DTS method provides promising potential in real-time seepage monitoring of embankment dams with the help of the developed DPAAS.

In this work, we performed a flume testing of seepage velocity monitoring platform using optical fiber distributed-temperature sensing for embankments based on the transient hot-wire method. Through the testing of data, the seepage velocity monitoring model particular to the experimental setup was established. The results presented here are very encouraging and demonstrate that the DTS system can be used to monitor the temperature and the seepage factors in field applications.

The purpose of this paper is to theoretically analyze and experimentally demonstrate the investigation of and present a kind of sensing system for monitoring simultaneous temperature and strain measurements based on highly nonlinear fiber (HNLF) and single mode fiber (SMF).

First, the stimulated Brillouin scattering (SBS) characteristics of the HNLF have been studied, including the Brillouin gain bandwidth, Brillouin gain center frequency and SBS threshold. Second, based on the Brillouin gain center frequency, the Brillouin frequency shift coefficients of strain and temperature in HNLF have been studied. Third, the sensing and signal interrogation scheme for simultaneous monitoring of temperature and strain with high resolution has been presented.

It is found that the HNLF has a wider Brillouin gain bandwidth. The SBS threshold of HNLF is 78 mW, which is much larger than 7.9 mW of SMF. Also, the Brillouin frequency shift coefficients of strain and temperature in HNLF are 0.0308 and 0.413 MHz/°C, respectively.

The larger threshold of SBS is useful to avoid SBS under certain situations that Spontaneous Brillouin Scattering is necessary and should be applied. The technique is based on the fact that the Brillouin frequency shift coefficients of strain and temperature in HNLF are different from those in SMF. Therefore, the two-parameter monitoring can be achieved by producing SBS and obtaining the back-scattering Brillouin signal light simultaneously in HNLF and SMF.

This paper presents a framework for analyzing e‐commerce security. The framework is developed by analyzing the relationships between e‐commerce security needs, threats, technologies and tools. Organizations can use the framework to evaluate and select security for e‐commerce.

The purpose of this paper is to investigate an online monitoring strategy that incorporates fiber Bragg gratings (FBGs) for deformation displacement detection, with the background that slope deformation monitoring is crucial to engineering safety supervision and disaster prevention.

A “beam element” method has been proposed, introduced and experimentally verified in detail. The deformation displacement along a flexible bar can be obtained based on this method, using the distributed strain detected by the FBGs embedded in the bar. A novel sensor structure containing inclinometer casings and a series of connected flexible pipes with FBGs embedded has been proposed. Based on the features of this structure, two FBG deformation sensors have been manufactured and installed into a slope. A matched monitoring station which permits real-time supervision, warning and remote access across the Internet was established and operated.

Displacement data from September 2013 to August 2014 are obtained, which is basically consistent with the practical situation.

The FBG deformation sensors demonstrated a robust and reliable measurement performance, which is promising for real-time disaster warning in slope engineering.

This paper aims to evaluate the effect of plasma treatment on the performance and color strength of pigment printed polypropylene nonwovens fabrics.

Melt spun nonwoven fabrics have been treated with plasma discharge using oxygen as a reactive gas to activate their surfaces for better interfacial interactions. The untreated and plasma treated fabrics are printed using pigment print pastes to investigate the print properties of nonwoven fabrics that are correlated to surface characteristics. The printed fabrics are characterized through FTIR, color fastness to washing and rubbing, flexural rigidity and moisture management observations.

The fabrics treated with oxygen plasma exhibited higher wettability, higher overall moisture management capability, enhanced color strength and superior color fastness to washing. However, bending length and flexural rigidity have been increased.

This study offers promising findings regarding the surface activation of polypropylene nonwovens for enhanced performance, comfort and color fastness characteristics.

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