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Landslides pose significant threats to human lives and infrastructure, and precise understanding and prediction are necessary for effective disaster mitigation. Traditional monitoring methods primarily focus on surface displacement monitoring, which has limitations in understanding the complex evolution of sliding surfaces. This also restricts the improvement in the accuracy and timeliness of deformation prediction models. This study takes the Xinpu landslide in the Three Gorges Reservoir area as an example, utilizing fiber Bragg grating (FBG) technology to monitor the shear strain and shallow soil moisture content during the landslide deformation process. Combining geotechnical and hydrological parameters, a shear strain prediction method considering deformation lag effect is proposed based on machine learning methods. Our findings demonstrate the effectiveness of FBG technology for accurate shear strain monitoring. The integration of hydrological and geotechnical parameters enhances strain prediction accuracy, reflecting the complex interplay of factors influencing landslide deformations. This study presents a shear strain prediction model for shallow sliding surface, contributing to early warning systems and landslide disaster management. [ABSTRACT FROM AUTHOR]

This paper presents a Fiber Bragg Grating (FBG)-based vibration sensor to measure the low frequency signals. The low frequency vibration signals are induced in heavy vehicle transport industries, coal mines, and oil and gas exploration industry. These low frequency vibration affects the musculoskeletal, vascular, and neurological systems of human body working with heavy vehicles and vibration-generating tools. A U-shape structure with a cantilever beam attached to FBG is proposed and illustrated experimentally. The sensitivity and resonant frequency of the vibration sensor are extrapolated theoretically, and the structural parameters were optimized by MATLAB and verified through COMSOL-based FEM analysis. The experimental result shows that the resonant frequency of the proposed vibration sensor is 94 Hz, the sensitivity in z-direction is 140 pm/g within the flat frequency range 0.5–70 Hz, and the lateral interferences are 3.94% and 2.8% in x and y directions, respectively. [ABSTRACT FROM AUTHOR]

Abstract Structural health monitoring (SHM) has become increasingly common in assessing built structures and the ongoing monitoring of older ones, whether for preventive maintenance applications or for assuring the integrity of deteriorating structures. Several sensing technologies have been developed and utilized for these applications. Over the past two decades, optical fiber sensors (OFS) have been utilized in various civil engineering projects due to their inherent advantages. This includes properties such as lightweight, size, immunity to electromagnetic interference (EMI), corrosion resistance, and embedding capability. Several monitoring systems based on OFS have been developed to measure and assess real-time data of various civil infrastructures continuously. Since its inception, Fiber Bragg grating (FBG) has been an ideal candidate for OFS technology; currently, most OFS systems use FBG. Due to its inherent characteristics and potential applications, considerable efforts and advancements have been made in the FBG-based sensing field. One of the most developed FBG sensors is strain OFS. Not just because of their benefits compared to the traditional strain gauge but also because of their high sensitivity and low cost. FBG strain sensors acquire an essential share of the SHM market. This review paper aims to give a general understanding of the basic principles of FBG sensors, advances in sensing and data processing techniques, developments of novel optical fiber sensors, temperature compensation techniques, and practical applications of FBG sensing technology in SHM. Moreover, this paper aims to contribute to the existing knowledge by highlighting the evolving landscape of FBG sensors and suggesting potential research areas in the context of SHM.

This paper focuses on the spectral analysis of fiber Bragg gratings written in nanostructured large mode area and few-mode fibers when fundamental and higher mode(s) are simultaneously excited. For this purpose, an advanced numerical tool was developed and validated. A method for modal decomposition and superposition was proposed, which overcomes the limitations of commercial software. In the presented approach, the intermodal coupling as a consequence of non-ideal fringe pattern spatial distribution in fiber Bragg gratins is also considered. The numerical tool increases the versatility of fiber Bragg grating spectral analysis, especially taking into account the unconventional optical fibers having independent photosensitivity and refractive index profiles and few-mode operation. [ABSTRACT FROM AUTHOR]

Purpose: The use of a force sensor to estimate the external force of manipulator not only needs to deal with the signal noise of the sensor itself but also needs to solve the coupling interference of the sensor itself, especially the axial force. The purpose of this paper is to develop a three-dimensional fiber Bragg grating (FBG) wrist force sensor, which has a simple structure and reduces the coupling influence between several axes. Design/methodology/approach: A particular separation elastic structure with four FBGs is devised for the three-axial force sensor. One FBG is suspended on the profile of central cylinder and the other three FBGs are pasted on the elastic beam surface of the over and under measuring bodies, respectively. Finite element analysis (FEA) simulation has been implemented to the strain distribution characteristics, the output characteristics of each direction and the coupling effects of the structure. Furthermore, theoretical derivation and experimental results are used to compare, which have a good consistency. Findings: The experiment results show that the maximum repeatability error of the sensor is 6.75%, the maximum nonlinear error is 5.36%, the maximum coupling interference is 4.73% and the minimum sensitivity is 1.58 pm/N. Originality/value: A three-dimensional force sensor based on FBG adopts a particular separation elastic structure. The sensor can reduce the coupling influence between several axes, especially the coupling interference in the z-direction is 0. [ABSTRACT FROM AUTHOR]

Continuous monitoring of Underwater Pipelines Temperature (UPT) is crucial for identifying and understanding various issues with oil pipeline operations. In this study, we propose a novel optical temperature sensor based on an apodized Fiber Bragg Grating (FBG) to measure variations in UPT. The choice of coating material and optimized grating profile significantly impacts the construction of the FBG sensor's head. Therefore, we conducted a comparative study of various coating materials to enhance the temperature sensitivity of the FBG and applied various apodized profiles to achieve high reflectivity, minimal sidelobes, and narrow bandwidth. Our comparative analysis reveals that the proposed sensor with optimal parameters demonstrates a temperature sensitivity of 168 pm/°C within the temperature range of 20 °C to 50 °C (i.e. ten times the commercial sensor) and a strain sensitivity of 12 pm/µɛ within the strain range of - 0.0015 µɛ to 0.0015 µɛ. The performance of the proposed PTFE-Coated temperature sensor is validated against commercial temperature sensors, indicating high temperature sensitivity. Consequently, we designed a multi-sensor simulation model incorporating the proposed sensor, and our observations indicate its effectiveness for underwater pipeline temperature monitoring. [ABSTRACT FROM AUTHOR]

The measurement of low frequency vibration signals is of great significance in seismic monitoring, health monitoring of large and medium-sized engineering structures, resource exploration, etc. A cross spring leaf-based novel FBG accelerometer was designed against the problem that it's hard for FBG acceleration sensors to effectively pick up low frequency vibration signals. Firstly, the vibration model of acceleration sensor was built and its operating principle was analyzed; secondly, the effect of structural parameters of sensor on their sensitivity and natural frequency was analyzed, and the sensor was subjected to static stress analysis and dynamic characteristics analysis through the ANSYS simulation software; finally, the sensors were subjected to performance tests with a low frequency vibration test system. Experimental results suggested that the natural frequency of FBG acceleration sensor was 63.65 Hz, it gives a flat sensitivity response in the low frequency band of 0.1–40 Hz; its sensitivity was not lower than 2000 pm/g, and the transverse interference was not higher than 1.99%; moreover, it offered favorable self-temperature compensation. Such FBG acceleration sensors with high sensitivity response at low frequencies provide important reference for the design of like sensors. [ABSTRACT FROM AUTHOR]

This paper presents the design of a convergent optical transport architecture for wireless and photonic sensor networks based on the optical access network deployed in Bogotá city. The proposed architecture is evaluated through the transport of services in subcarrier division multiplexing to enable the seamless transport of different standards such as WiFi, Bluetooth, Zigbee, SigFox, among others. The proposed design demonstrates high scalability given the distribution of the previously deployed network, enabling the incorporation of both optical sensors based on FBG and wireless sensors in locations with greater historical, economic, cultural and social relevance. The proposal presents an optimal response in terms of bit error rate (BER) and signal power in the multi-coverage zone for various interference parameters such as SS-RSRP, SS-RSRQ, and Throughput.

In open Radio access network (oRAN) 5G networks, a fronthaul segment between virtual Distribution unit (vDU) edge cloud and other external Remote radio units (RRUs) sites is very important to transmit high data rate to achieve 5G requirements. Performance parameters such as Quality factor (Q-factor) and Bit error rate (BER) of an optical fiber fronthaul segment are the main important parameters to enhance latency and bit rate. An Apodized fiber bragg grating (AFBG) is utilized with different apodization profiles to optimize linewidth of an optical signal leading to enhance performance. The designed AFBG is used with a data rate of 25 Gb/s optical Ethernet module at the vDU edge cloud to optimize the linewidth of the optical signal between the vDU and the RRU in the fronthaul optical fiber segment. The AFBG is investigated at different connections pre, post, and symmetrical connections, where different apodization functions are used in the AFBG design. It is found that the best results for the maximum Q-factor and minimum BER are 9.2 and 2.72e− 21, respectively, obtained from uniform function in the symmetrical connection. Finally, the proposed model linewidth is 0.408 nm, which is better than 1.56 nm that is evaluated by related work. [ABSTRACT FROM AUTHOR]

Explosive increase in internet services put peer pressure on conventional band grid (1530–1570 nm) and therefore L-band wide wavelength grid is required to cater the ever-increasing demands. In this work, accentuation is given to enhance the gain flattening of ultradense (25 GHz) L-band WDM system using single stage EDFA amplifier when ultralow power is launched from 16 and 32 channels. High gain and gain flattening is achieved by incorporating three fiber Bragg gratings (FBGs) for amplified spontaneous noise reinjection. Maximum Amplified spontaneous emission (ASE) is emerged at 1565 nm for the 1575.69–1579 nm input wavelengths (16 channels) and 1572.58–1579 nm (32 channels) at −55 dBm ultra low carrier powers. To optimize different parameters of L-band EDFA, different physical parameters such as core radius, EDF link lengths, and launched powers are varied, and results are analyzed in terms of lateness. Maximum gain is found out to be 34.12 dB at optimal physical parameters of the EDF with gain flatness of ±0.45 dB in case of 16 channels and ±1.41 in case of 32 channels. [ABSTRACT FROM AUTHOR]

The measurement of low-frequency vibration signals is of great significance for the studies on the seismic monitoring of railway transportation, bridges, and civil building structures. Aiming at the problem that the existing cantilever-type FBG acceleration sensors are difficult to effectively pickup low-frequency vibration signals and that they are large in size, a double cantilever beam-based miniaturized low-frequency FBG acceleration sensor is proposed. Firstly, the vibration model of the acceleration sensor is built, and its working principle is analyzed; secondly, the effect of structural parameters of the sensor on its sensitivity and natural frequency is analyzed, and the structural parameters of the sensor are optimized by the ANSYS simulation software; finally, the real sensor is developed, and a low-frequency vibration test system is set up to test the performance of the sensor. The experiment result suggests that the natural frequency of the sensor is about 71.4 Hz; the low-frequency vibration signals can be effectively picked up in the frequency range of 0.1–2 Hz; favorable linearity is observed in the operating frequency band of 2–50 Hz; the sensitivity is about 1022.8 pm/g, and the dynamic range is 74.5 dB; the transverse interference is not higher than 4.2%, and the volume is merely 7 cm3, which is significantly reduced compared to similar FBG acceleration sensors. The research findings provide a reference for the development of miniaturized low-frequency FBG accelerator sensors. [ABSTRACT FROM AUTHOR]

Monitoring shear deformation of sliding zones is of great significance for understanding the landslide evolution mechanism, in which fiber optic strain sensing has shown great potential. However, the correlation between strain measurements of quasi-distributed fiber Bragg grating (FBG) sensing arrays and shear displacements of surrounding soil remains elusive. In this study, a direct shear model test was conducted to simulate the shear deformation of sliding zones, in which the soil internal deformation was captured using FBG strain sensors and the soil surface deformation was measured by particle image velocimetry (PIV). The test results show that there were two main slip surfaces and two secondary ones, developing a spindle-shaped shear band in the soil. The formation of the shear band was successfully captured by FBG sensors. A sinusoidal model was proposed to describe the fiber optic cable deformation behavior. On this basis, the shear displacements and shear band widths were calculated by using strain measurements. This work provides important insight into the deduction of soil shear deformation using soil-embedded FBG strain sensors.

Optical fiber Bragg grating (FBG) technology offers many advantages over conventional electrical sensors for the measurement of fluid-structure interaction (FSI). In this work, FBGs are used to measure the dynamic response of 3 mm, 2 mm, and 1 mm thick aluminum cantilever panels under the influence of Mach 2 reflected shock impingement in the UNSW Canberra supersonic blowdown facility. Results compared during start-up and steady-state with high-speed digital video schlieren and laser Doppler vibrometry indicate that FBGs can successfully capture the temporal and spectral characteristics of high-speed FSI. The torsional mode of the 1 mm plate is spectrally captured by the FBG with only a single sensor. Furthermore, it is shown that error in the FBG signal is comparable to that of a laser Doppler vibrometer. The greatest challenge remains the efficient decoupling of thermal effects.

Pipeline networks are the most reliable and efficient means of transporting oil, gas, and fluids across extensive distances. Therefore, monitoring pipelines continuously and ensuring their correct operation is essential. In this work, we investigated the capability of Fiber Bragg grating (FBG) in monitoring localized and uniform metal loss produced inside pipelines repaired with composite sleeves. We performed numerical simulations using finite element method (FEM) to characterize the hoop strain of different wrapped pipeline structures, including those with glass fiber reinforced polymer (GFRP) and with carbon fiber reinforced polymer (CFRP) sleeves. Besides, we investigated the strain at various locations, including the pipe wall’s outer surface and the sleeve’s external surface. The numerical results demonstrate that the hoop strain produced by internal pressure can be transmitted to the top surface of the composite sleeve, and its magnitude increases under the presence of metal loss. Furthermore, we corroborated these numerical results by conducting experiment tests using two pipe sections repaired with 7 mm-GFRP and 6 mm-CFRP composite sleeves and an array of FBGs to monitor the hoop strain variation on the steel pipe and the sleeves in response to applied strain at areas affected by metal loss with various depth sizes. The experimental results show that the minimum detectable metal loss thickness are 0.832 mm using FBG on the steel pipe and 1.04 mm using FBG on 7 mm-GFRP sleeve, and 0.2 mm using FBG on the steel pipe and 0.429 mm using FBG on a 6 mm-CFRP sleeve, considering an internal pressure of ~1800 psi, and the case where the FBG is at the location of the metal loss defect. The obtained results prove that this non-destructive and non-intrusive approach harnessing FBG sensors placed on the composite sleeve effectively monitors the internal metal loss and ensures the continuous inspection of pipeline integrity.

Compact, low‐inertia, and soft compliant robotic joint mechanisms are in great demand for ensuring safe interactions in human–robot collaborative tasks. Tensegrity, of which the structural integrity is constrained by tension, does not involve static/sliding friction among the rigid components. However, this mechanical stability is very susceptible to actuation errors. It requires complex kinematics modeling and sophisticated control model with sensing feedback. Herein, a low‐inertia tensegrity joint that is covered/protected by a fiber Bragg grating (FBG)‐embedded silicone sheath is proposed, with the aim to reinforce the joint motion stability and enable self‐contained sensing feedback. A learning‐based closed‐loop controller is also designed and trained with the proper joint configurations selected by a two‐step sampling method. Both the kinematics and static equilibriums of such configurations can be well satisfied. The experiments demonstrate that the joint can follow paths accurately in 2D by compensating manipulation error shortly under the closed‐loop control. The joint stiffness can also be varied against the external/impulsive disturbances. It can be foreseen that this primitive robot joint component with 2 degrees of freedom (DoFs) can provide safe, compliant interaction with human, for which a simple test of maneuvering a portable ultrasound probe (≈210 g) for abdominal imaging is demonstrated. [ABSTRACT FROM AUTHOR]

Copyright of Piezoelectrics & Acoustooptics is the property of Piezoelectric & Acoustooptic and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

The combination of phase change materials (PCMs) with building materials is a flourishing technology owing to the low-temperature change of the materials during phase change and the potential for enhanced heat storage and release. In this study, a new type of PCM energy pile, in which 20 stainless steel tubes (22 mm in diameter and 1400 mm in length) filled with paraffin were bound to heat exchange tubes, was proposed. An experimental system monitored by a fiber Bragg grating (FBG) to study the thermo-mechanical behavior of energy piles and surrounding soil was established. Both the PCM pile and the ordinary pile, with the same dimensions, were tested under the same experimental conditions for comparison. The results indicate that the temperature sensitivity coefficient calibration results of the FBG differ from the typical values by 8%. The temperature variation is more obvious in the ordinary pile and surrounding soil. The maximum thermal stress of the ordinary energy pile is 0.5~0.6 times larger than that of the PCM pile under flow rates ranging from 0.05 m3/h to 0.25 m3/h. The magnitudes of the pore water pressure and soil pressure variations were positively correlated with the flow rates. [ABSTRACT FROM AUTHOR]

Fiber-reinforced polymer (FRP) composites are considered suitable candidates for structural materials of spacecrafts due to their excellent properties of high strength, light weight, and corrosion resistance. An online health monitoring method for FRP composites must be applied to space structures. However, the application of existing health monitoring methods to space structures is limited due to the harsh space environment. Here, carbon fiber-reinforced polymer (CFRP) composites embedded with fiber Bragg grating (FBG) sensors were prepared to explore the feasibility of strain monitoring using embedded FBG sensors in γ-radiation environment. The analysis of the influence of radiation on the strain monitoring demonstrated that the embedded FBG can be successfully applied to the health monitoring of FRP composites in radiation environment.

Compact, low‐inertia, and soft compliant robotic joint mechanisms are in great demand for ensuring safe interactions in human–robot collaborative tasks. Tensegrity, of which the structural integrity is constrained by tension, does not involve static/sliding friction among the rigid components. However, this mechanical stability is very susceptible to actuation errors. It requires complex kinematics modeling and sophisticated control model with sensing feedback. Herein, a low‐inertia tensegrity joint that is covered/protected by a fiber Bragg grating (FBG)‐embedded silicone sheath is proposed, with the aim to reinforce the joint motion stability and enable self‐contained sensing feedback. A learning‐based closed‐loop controller is also designed and trained with the proper joint configurations selected by a two‐step sampling method. Both the kinematics and static equilibriums of such configurations can be well satisfied. The experiments demonstrate that the joint can follow paths accurately in 2D by compensating manipulation error shortly under the closed‐loop control. The joint stiffness can also be varied against the external/impulsive disturbances. It can be foreseen that this primitive robot joint component with 2 degrees of freedom (DoFs) can provide safe, compliant interaction with human, for which a simple test of maneuvering a portable ultrasound probe (≈210 g) for abdominal imaging is demonstrated.

This paper presents a comprehensive study of the Gaussian Apodized Fiber Bragg Grating (GA-FBG) as a stand-alone dispersion compensator for a 150 km long optical link. The main objective of this study is to investigate the performance of GA-FBG in various compensation modes and determine the maximum transmission distance it can support as a solo dispersion compensation unit. To achieve a more cost-effective optical link, we use the GA-FBG implementation as a substitute for the expensive Dispersion-Compensating Fiber in the network. To optimize the performance, the study explores three different compensation modes and analyses the grating parameters of the GA-FBG, taking into consideration all practical limitations of a fiber Bragg grating (FBG) in the design. The optimized links are assessed based on their performance characteristics using a Bit Error Rate analyzer. After optimizing the GA-FBG and the channel parameters of the link, the results demonstrate that the GA-FBG exhibits excellent dispersion compensation capabilities. The symmetrical compensation mode yields a remarkable Q-factor value, enabling transmission distances beyond 500 km with ease. Finally, to validate the functionality of the proposed system, we use the OptiSystem software. Our findings demonstrate that the GA-FBG can effectively compensate for dispersion, achieving a more cost-effective and efficient optical link with great potential for long-distance transmission. [ABSTRACT FROM AUTHOR]

Radio over Fiber technology is a promising solution for next-generation wireless communication networks. In radio over fiber systems, signal distortions caused by modulator nonlinearity is a major concern. In this paper, a full duplex dispersion compensating system using chromatic dispersion is proposed. A system using 16 QAM OFDM signal transmission is presented. Distortion compensation is observed when a required amount of dispersion is added. Bit Error Rate (BER) and constellation diagrams for different amount of dispersion are analyzed and its comparison is presented. Since the framework utilizes just a single persistent wave laser for upstream and downstream transmission the base station is additionally disentangled and it diminishes the general framework cost. Signal distortions are reduced when the dispersion is adjusted to 640 ps/nm for uplink transmission and 760 ps/nm for downlink transmission. [ABSTRACT FROM AUTHOR]

The accurate measurement of low-frequency signal is the main research focus at present. Aiming at the problem that FBG accelerometer is difficult to measure vibration signal efficiently, we propose a low-frequency FBG accelerometer based on dual mass. Build the vibration model of the sensor, derive the theoretical formula of the sensitivity and resonant frequency, and use COMSOL software to optimize the design and simulation of the key parameters. According to the theoretical analysis results of finite element verification, the sensor is manufactured and its performance is tested. The experimental results show that the transverse crosstalk of the sensor is − 28.07 dB, the relative standard deviation of repeatability is 0.90%, the fitting determination coefficient R2 is 99.98%, the sensitivity is 1194.91 pm/g, the dynamic range is 81.55 dB, the working frequency range is 1–40 Hz, and the inherent frequency is 58 Hz. In the low frequency band, the developed sensor exhibits good stability and sensitivity. This design provides a reference for the application of FBG accelerometer in low-frequency exploration. [ABSTRACT FROM AUTHOR]

In order to study the influence of split grouting times on the anchorage performance of prestressed anchor cable, a field test of multisplit grouting was carried out using fiber Bragg grating monitoring technology. The ultimate bearing capacity, displacement, axial force, and shear stress distribution of the anchor cable under different split grouting times were studied. The test results show that (1) compared with conventional grouting methods, multiple split grouting can increase the bearing capacity of the anchor cable by two to three times, and the improvement effect is most obvious in secondary grouting; (2) the number of split grouts has no effect on the axial force of the anchorage section and does not change the shear stress distribution of the anchorage section. The axial and shear stresses of the anchor cable are mainly concentrated at the first 8 m of the anchorage section. With the increasing tension load, debonding and sliding will occur at the front of the anchorage section, and the peak shear stress will move to the depth of the anchorage section. (3) When the anchor cable fails, the total displacement increases with the increase in splitting and grouting times. The conventional grouting anchor cable begins to produce plastic displacement early, while the plastic displacement of the split grouting anchor cable occurs when the external load is close to the failure load. (4) The multiple high-pressure split grouting technology is applicable to the reinforcement of foundation pits or slope engineering and is a valuable support and reinforcement technology. [ABSTRACT FROM AUTHOR]

The capabilities of Fiber Bragg Grating (FBG) sensors to measure temperature variations in the bulk of liquid flows were considered. In the first step of our research project, reported in this paper, we investigated to what extent the use of thin glass fibers without encapsulation, which only minimally disturb a flow, can fulfill the requirements for robustness and measurement accuracy. Experimental tests were performed in a benchmark setup containing 24 FBG measuring positions, which were instrumented in parallel with thermocouples for validation. We suggest a special assembly procedure in which the fiber is placed under a defined tension to improve its stiffness and immobility for certain flow conditions. This approach uses a single FBG sensor as a reference that measures the strain effect in real time, allowing accurate relative temperature measurements to be made at the other FBG sensor points, taking into account an appropriate correction term. Absolute temperature readings can be obtained by installing another well-calibrated, strain-independent thermometer on the reference FBG. We demonstrated this method in two test cases: (i) a temperature gradient with stable density stratification in the liquid metal GaInSn and (ii) the heating of a water column using a local heat source. In these measurements, we succeeded in recording both spatial and temporal changes in the linear temperature distribution along the fiber. We present the corresponding results from the tests and, against this background, we discuss the capabilities and limitations of this measurement technique with respect to the detection of temperature fields in liquid flows. [ABSTRACT FROM AUTHOR]

In this paper, we proposed and experimentally demonstrated the association of a fiber Bragg Grating (FBG) sensing system with You Only Look Once V7 (YOLO V7) to identify the vibration signal of a faulty machine. In the experiment, the YOLO V7 network architecture consists of a backbone, three detection heads (Headx3), a path aggregation network (PAN), and a feature pyramid network (FPN). The proposed architecture has an FBG sensor and the FBG interrogator employed for collecting sensing vibration signals or vibration data when degradation or fault occurs. An FBG interrogator collects vibration data independently, and then the YOLO V7 object detection algorithm is the recognition architecture of the vibration pattern of the signal. Thus, the proposed vibration recognition or detection is an assurance for detecting vibration signals that can support monitoring the machine's health. Moreover, this research is promising for ensuring a high accuracy detection of faulty signals rate in industrial equipment monitoring and offers a robust system, resulting in remarkable accuracy with an overall model accuracy of 99.7%. The result shows that the model can identify the faulty signal more accurately and effectively detect the faulty vibration signal using the detection algorithm. [ABSTRACT FROM AUTHOR]

Abstract This paper describes the automation of a forearm prosthesis using the signal collected by a Fiber Bragg Grating (FBG) sensor. The FBG sensor is applied to one subject's forearm to measure the deformation as a result of the index and middle fingers when moved individually. It is possible to control a one joint model prosthesis allied to a compliant hand mechanism through signal analyses. Each finger movement has its features, such as its amplitude, which opens the possibility of using those to control different parts of the prosthesis, joint rotation by the middle finger, and compliant hand movement by the index finger. This paper presents results regarding prosthesis assembling, Hypertext Transfer Protocol (HTTP) communication latency between prosthesis and computer and tests with pre-acquired and processed FBG signal data. The prosthesis wrist rotation movement is related to the middle finger signal, and its compliant mechanism actuation is due to index finger signal. The communication between prosthesis and the computer had a mean latency of 140 ms and a standard deviation of 18 ms. The results demonstrate the potential for using the sensor system and automated prosthesis in other applications involving real-time forearm sensing, multi-finger signal analysis, and prosthetic movement.

This study presents the development and rigorous evaluation of a Fiber Bragg Grating (FBG)-based Outside Air Temperature (OAT) sensor designed for aircraft applications. Employing a Design of Experiments (DoE) approach, the research optimized the sensor's performance for reliability, accuracy, and durability in aviation environments. Experimental assessment covered detailed installation of the FBG sensor on an aircraft, considering influential parameters such as outside dimensions and varying temperature. The OAT sensor's design focused on robustness and precision for accurate real-time temperature recording, vital for operational efficiency and safety. Extensive statistical analysis assessed the sensor's performance under differing conditions, providing valuable insights into operational capabilities and overall efficacy. Thermo-climatic chamber tests simulated extreme environmental conditions to validate the sensor's durability and function under potential aircraft operational scenarios. This research enhances understanding of FBG-based OAT sensors for aircraft applications, demonstrating their superior robustness and performance capabilities, thereby contributing to aviation safety, operational efficiency, and data precision.© 2017 Elsevier Inc. All rights reserved.

This research investigates fiber Bragg grating (FBG) temperature sensing performance in monitoring non--uniformity of non-thermal plasma (NTP) formation in a packed-bed reactor using FBG operating at atmospheric pressure. Two FBGs made from germanium doped fiber were embedded inside and outside the PBNTP reactor to allow for comparison between the temperatures inside and outside of the reactor to be made. Each FBG comes with three grating series, which allow the reactor temperatures at three different locations inside or outside the reactor to be measured and compared. Two types of plasma, namely nitrogen (N2) and argon (Ar) were generated in the reactor at a gas flow rate in the range of 2 - 7 L/min and applied voltage in the range of l - 20 kV. It was found that the PBNTP reactor temperature varies up to 20 oC at different positions inside and up to 40 oC outside of the reactor. This finding shows the non-uniformity of plasma formation and the nature of the plasma's localized thermodynamic equilibrium (LTE). The sensitivity of the FBG temperature sensor used in this study is estimated at 10.36 - 10.50 pm/oC. [ABSTRACT FROM AUTHOR]

The stay cable is one of the most critical structural components of a cable dome structure. However, during its service life, it may lose its stiffness due to environmental factors and metal fatigue, thus making the structure a safety hazard. As the most important mechanical physical parameter of the cable, it is necessary to create a health-monitoring method to ensure the safety of the structure. In this study, a smart cable with a fiber optic Bragg grating (FBG) sensor is proposed. The sensor is embedded in the Z-shaped cable of the stay cable to ensure the simultaneous deformation of the sensor and cable. The monitoring of the cable force can be achieved after obtaining the relationship coefficient between the sensor and the cable force. In the rest of the paper, the sensing principle and fabrication procedure are described. A series of tests are conducted to verify the sensing performance of the smart cable. Finally, the dynamic monitoring and long-term monitoring of the cable force in the cable-supported grid system of Dalian Suoyuwan Football Stadium are carried out by using the smart cable, and the stability and safety of the structure are evaluated by the monitoring results. [ABSTRACT FROM AUTHOR]

This paper proposes a Fiber Bragg Grating (FBG) stress detection technology based on Empirical Mode Decomposition (EMD) for suspended permanent magnet maglev box girder, which is used to detect the stress of the track box girder when the vehicle passes through, check whether the stress is within the safe range, and ensure the operation safety and stability of vehicles. Considering the influence of strong magnetic field and electromagnetic interference, the FBG grating sensing stress detection scheme without electricity on the track is adopted, and a test point is respectively arranged at the travel position of the upper and lower guide wheels. The FBG test point is subject to both low-frequency flexure stress and high-frequency guide wheel stress, and the EMD method is used to separate the two stresses. The experimental results show that the test results of vehicle passing stress in line with expectations. The stress detection technology for track box girder described in this paper can effectively ensure the health of track box girder and the operation safety of vehicles. [ABSTRACT FROM AUTHOR]

The pressure measurement in the high-temperature liquid metal system, such as Sodium-cooled Fast Reactor(SFR), is important and yet it is very challenging due to its nature. The measuring pressure is relatively at low range and the applied temperature varies in wide range. Moreover, the pressure transfer material in impulse line needs to considered the high temperature condition. The conventional diaphragm-based approach cannot be used for it is impossible to remove the effect of thermal expansion. In this paper, the Fiber Bragg Grating(FBG) sensor-based pressure measuring concept is suggested that it is free of problems induced by the thermal expansion. To verify this concept, a prototype was fabricated and tested in an appropriate conditions. The uncertainty analysis result of the experiment is also included. The final result of this study clearly showed that the FBG-based pressure transmitter system is applicable to the extreme environment, such as SFR and any other high-temperature liquid metal system and the measurement uncertainty is within reasonable range.

This report presents a comprehensive approach to dispersion management, including various techniques, mathematical analysis, and their advantages and disadvantages in different scenarios. A deep mathematical analysis of chirped fiber Bragg grating (CFBG) is conducted for various chirping techniques and apodization profiles, highlighting the importance of this aspect in dispersion management. Additionally, a detailed study of the implementation of CFBG and dispersion compensating fiber (DCF) is performed to determine which technique is suitable for long-haul links and which is best for WDM networks, both for low and high capacity. The report also sheds light on how dispersion compensation techniques can be useful in mm wave propagation. The paper provides new insights into the field of dispersion management and the results of the study make it an interesting and valuable addition to the literature. [ABSTRACT FROM AUTHOR]

The real-time evaluation of slope stability is a crucial technical issue in foundation excavation and slope construction. However, conventional monitoring methods often fall short of achieving real-time and accurate measurements, which poses challenges to the timely assessment of slope stability. To address this problem, laboratory tests and numerical simulations were jointly used to evaluate slope stability in this paper. In numerical simulations, the finite element method (FEM) results clearly illustrate the distribution and evolution of internal strain during slope excavation, and the limit equilibrium method (LEM) calculates changes in the safety factor. In laboratory tests, the fiber Bragg grating (FBG) sensing technology was employed to monitor the internal strain of the slope in real time. The distribution characteristics of the slope internal strain field under the condition of stepped excavation were analyzed, and the feasibility of strain-based evaluation of slope stability was discussed. The measurements with FBG sensing technology agree well with the numerical simulation results, indicating that FBG can effectively monitor soil strain information. Of great significance is that the maximum horizontal strain of the slope is closely related to the safety factor and can be used to evaluate slope stability. Notably, the horizontal soil strain of the slope provides insight into both the formation and evolution of the critical sliding surface during excavation. The combination of numerical simulation and intelligent monitoring technology based on FBG proposed in this paper provides a reference for capturing strain information inside the slope and realizing real-time assessment and critical warning of slope stability. [ABSTRACT FROM AUTHOR]

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This article reports a distributed thermal monitoring approach for permanent magnet synchronous motors (PMSMs). The detecting system is based on using an electrically non-conductive and electromagnetic interference-free fiber Bragg grating (FBG) temperature sensor embedded in the stator of PMSMs. FBG thermal sensors with different annealing temperature were fabricated and integrated with a motor stator, and their accuracy for temperature measurement was evaluated. According to the experimental results, the error within 200 °C is limited between −6 °C and 2 °C when the annealing temperature is 95 °C, and the error decreases to ±1 °C when the annealing temperature is 120 °C, indicating that performance of FBG thermal sensor is improved by increasing the annealing temperature. This article provides methodogical guidance for improving the accuracy of stator temperature distribution measurements based on the FBG thermal sensor. [ABSTRACT FROM AUTHOR]