Recent Advances in Structural Health Monitoring

Journal Name	Impact Factor	CiteScore	Launched Year	First Decision (median)	APC
Acoustics acoustics	2.1	4.0	2019	16.3 Days	CHF 1600
Applied Sciences applsci	2.7	4.5	2011	16.9 Days	CHF 2400
Materials materials	3.4	5.2	2008	13.9 Days	CHF 2600
Sensors sensors	3.9	6.8	2001	17 Days	CHF 2600
Buildings buildings	3.8	3.1	2011	14.6 Days	CHF 2600

17 pages, 6472 KiB

Open AccessArticle

An Experimental Investigation on the Foliation Strike-Angle Effect of Layered Hard Rock under Engineering Triaxial Stress Path

by Zhaofeng Wang, Guangliang Feng, Xufeng Liu and Yangyi Zhou

Materials 2023, 16(17), 5987; https://doi.org/10.3390/ma16175987 - 31 Aug 2023

Viewed by 646

Abstract

Deep underground engineering encounters substantial layered hard rock formations, and the engineering triaxial stress path involves an increase in maximum principal stress, constant intermediate principal stress, and a decrease in minimum principal stress. However, previous research has focused on rock layer angles under [...] Read more.

Deep underground engineering encounters substantial layered hard rock formations, and the engineering triaxial stress path involves an increase in maximum principal stress, constant intermediate principal stress, and a decrease in minimum principal stress. However, previous research has focused on rock layer angles under conventional triaxial stress conditions, disregarding the influence of foliation strike angles in engineering triaxial stress scenarios. This study experimentally investigates the effects of foliation strike angles on layered hard rock under an engineering triaxial stress path. To account for the brittleness of layered hard rock, we propose a specific small sample-processing method tailored to the foliation strike angle. True triaxial loading tests are conducted on steep, thin slate samples with two different loading orientations, accompanied by acoustic emission monitoring. Results indicate that the strength under a traditional true triaxial compression condition is similar for specimens with 90° and 0° strike angles. Stress–strain curves show that larger deformations occur perpendicular to bedding planes, while surface fractures propagate exclusively along the bedding planes. Mechanical responses differ significantly between specimens subjected to the engineering triaxial stress path at 0° and 90° strike angles compared to conventional true triaxial loading tests, with a lower bearing capacity and differentiated intermediate and minimum principal strains in the 0° case. Conversely, the 90° case exhibits a higher bearing capacity, consistent deformation, and more acoustic emission events. Numerical simulations comparing plastic zone sizes during actual underground excavation support these conclusions. These findings highlight the effects of foliation strike angles, favoring the 90° strike-angle configuration for excavation activities and providing enhanced stability in the surrounding rock mass. Full article

(This article belongs to the Topic Recent Advances in Structural Health Monitoring)

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20 pages, 7198 KiB

Open AccessArticle

Identification and Tracking of Vehicles between Multiple Cameras on Bridges Using a YOLOv4 and OSNet-Based Method

by Tao Jin, Xiaowei Ye, Zhexun Li and Zhaoyu Huo

Sensors 2023, 23(12), 5510; https://doi.org/10.3390/s23125510 - 12 Jun 2023

Cited by 1 | Viewed by 1339

Abstract

The estimation of vehicle loads is a rising research hotspot in bridge structure health monitoring (SHM). Traditional methods, such as the bridge weight-in-motion system (BWIM), are widely used but they fail to record the locations of vehicles on the bridges. Computer vision-based approaches [...] Read more.

The estimation of vehicle loads is a rising research hotspot in bridge structure health monitoring (SHM). Traditional methods, such as the bridge weight-in-motion system (BWIM), are widely used but they fail to record the locations of vehicles on the bridges. Computer vision-based approaches are promising ways for vehicle tracking on bridges. Nevertheless, keeping track of vehicles from the video frames of multiple cameras without an overlapped visual field poses a challenge for the tracking of vehicles across the whole bridge. In this study, a method that was You Only Look Once v4 (YOLOv4)- and Omni-Scale Net (OSNet)-based was proposed to realize vehicle detecting and tracking across multiple cameras. A modified IoU-based tracking method was proposed to track a vehicle in adjacent video frames from the same camera, which takes both the appearance of vehicles and overlapping rates between the vehicle bounding boxes into consideration. The Hungary algorithm was adopted to match vehicle photos in various videos. Moreover, a dataset with 25,080 images of 1727 vehicles for vehicle identification was established to train and evaluate four models. Field validation experiments based on videos from three surveillance cameras were conducted to validate the proposed method. Experimental results show that the proposed method has an accuracy of 97.7% in terms of vehicle tracking in the visual field of a single camera and over 92.5% in tracking across multiple cameras, which can contribute to the acquisition of the temporal–spatial distribution of vehicle loads on the whole bridge. Full article

(This article belongs to the Topic Recent Advances in Structural Health Monitoring)

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17 pages, 4167 KiB

Open AccessFeature PaperArticle

Effects of the Ventilation System by Using Jet Fans during a Fire in Road Tunnels

by Amir Nematollahi Sarvestani and Pierpaolo Oreste

Appl. Sci. 2023, 13(9), 5618; https://doi.org/10.3390/app13095618 - 02 May 2023

Cited by 2 | Viewed by 2010

Abstract

People inside a road tunnel may be in grave danger if there is a fire. When a fire is developing, mechanical ventilation can be crucial in protecting occupants and facilitating the arrival of emergency crews. In this paper, a new calculation method that [...] Read more.

People inside a road tunnel may be in grave danger if there is a fire. When a fire is developing, mechanical ventilation can be crucial in protecting occupants and facilitating the arrival of emergency crews. In this paper, a new calculation method that can analyze the evolution of the fire and of the airflow is illustrated. An assumed fire inside an 800 m long one-way road tunnel in Northern Italy was dealt with using the developed method. Subsequently, the acquired results were successfully compared to those of numerical modeling. By varying the position of the fire inside the studied tunnel, it was then possible to detect situations of high risk for the people when the fire is located at a limited distance from the upstream entrance. The newly developed calculation procedure was then able to verify how a simple different positioning of the pairs of jet fans inside the tunnel can eliminate the risks that people intent on escaping towards the upstream entrance can be reached by the fire fumes (back-layering phenomenon). It can therefore be a useful tool to improve the jet fan design in one-way road tunnels in accordance with safety principles. Full article

(This article belongs to the Topic Recent Advances in Structural Health Monitoring)

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15 pages, 15784 KiB

Open AccessArticle

Eddy Current Sensors Optimization for Defect Detection in Parts Fabricated by Laser Powder Bed Fusion

by Romain Saddoud, Natalia Sergeeva-Chollet and Michel Darmon

Sensors 2023, 23(9), 4336; https://doi.org/10.3390/s23094336 - 27 Apr 2023

Cited by 1 | Viewed by 1819

Abstract

The production of parts by additive manufacturing is an important issue for the reduction in manufacturing costs and the creation of complex geometries. Optical inspection is often implemented in the machines during the manufacturing process in order to monitor the possible generated defects. [...] Read more.

The production of parts by additive manufacturing is an important issue for the reduction in manufacturing costs and the creation of complex geometries. Optical inspection is often implemented in the machines during the manufacturing process in order to monitor the possible generated defects. However, it is also crucial to test the quality of the manufactured parts after their fabrication and monitor their health throughout their industrial lifetime. Therefore structural health monitoring (SHM) methods need to be studied or designed. In this paper, the eddy current method is used to control fabricated parts, as this technique is adapted to detect surface and shallow defects in conductive materials. Using simulations with the CIVA non-destructive testing software package, several sensors and their parameters were tested in order to determine the most optimal ones: a separate transmitter/receiver sensor and an isotropic sensor were finally designed. The comparison of these sensors’ efficiency was made on the detection of notches and engraved letters based on simulation and experimental tests on parts fabricated by laser powder bed fusion (L-PBF) in order to determine the optimal sensor. The various tests showed that the isotropic sensor is the optimal one for the detection and characterization of defects. Full article

(This article belongs to the Topic Recent Advances in Structural Health Monitoring)

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16 pages, 5454 KiB

Open AccessReview

A Review of Conceptual Design and Self Health Monitoring Program in a Vertical City: A Case of Burj Khalifa, U.A.E.

by Danjuma Abdu Yusuf, Abubakar Ahmed, Abdullahi Sagir, Abdulfatah Abdu Yusuf, Adamu Yakubu, Abdullahi T. Zakari, Abdullahi M. Usman, Abdullahi S. Nashe and Abdulmalik Sule Hamma

Buildings 2023, 13(4), 1049; https://doi.org/10.3390/buildings13041049 - 17 Apr 2023

Cited by 2 | Viewed by 4776

Abstract

Burj Khalifa, a notable landmark in a growing landscape of skyscrapers, along with other tall structures, has dramatically transformed the morphology of Dubai and elevated it to global prominence. This masterpiece was designed to attract international interest, as it diversifies the economy from [...] Read more.

Burj Khalifa, a notable landmark in a growing landscape of skyscrapers, along with other tall structures, has dramatically transformed the morphology of Dubai and elevated it to global prominence. This masterpiece was designed to attract international interest, as it diversifies the economy from an oil-based one towards one that is tourist-and servicebased. However, the foremost design input and major challenges of the super-tall building are associated with the increase in height, which put them at risk of wind- and earthquake-induced lateral loads and user satisfaction. Consequently, it was essential to study both the design and construction phases of the tallest towers in the context of the wind and earthquake impact. This study aims to revalidate the three structural design phases; conceptual, schematic, and detailed design of this vertical city to confirm that the requirements are achieved. The methodology is a theoretical and analytical elaboration of the case study that obtains and confirms the basic requirements through a review of the existing survey, drawings, literature, and archived documents. Finally, the study validates the presumed structural behaviour and the insitu determined response, which are outstanding. The study further unveils the development of the structural health monitoring programme that gives an instant and direct response to the real structural performance of the building from the commencement of the construction and throughout its lifespan. Full article

(This article belongs to the Topic Recent Advances in Structural Health Monitoring)

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14 pages, 2680 KiB

Open AccessArticle

Fire Scenarios Inside a Room-and-Pillar Underground Quarry Using Numerical Modeling to Define Emergency Plans

by Amir Nematollahi Sarvestani, Pierpaolo Oreste and Sandro Gennaro

Appl. Sci. 2023, 13(7), 4607; https://doi.org/10.3390/app13074607 - 05 Apr 2023

Cited by 3 | Viewed by 1376

Abstract

Underground fires are still one of the most significant risks in mines today. In order to manage this risk, it is necessary to know the potential evolution of a fire and the effects it can have on people and other objects. Ventilation plays [...] Read more.

Underground fires are still one of the most significant risks in mines today. In order to manage this risk, it is necessary to know the potential evolution of a fire and the effects it can have on people and other objects. Ventilation plays an essential role in the development of a fire; it also influences the propagation of toxic fumes and the variation of temperatures in all other areas of a mine. Currently, it is possible to jointly analyze, through numerical modeling, the ventilation circuit and a fire for different possible scenarios in order to define, in detail, the emergency plans that need to be adopted. In this paper, a numerical study was conducted via the use of Ventsim Software (an integrated mine and tunnel ventilation numerical package that is able to analyze airflows, pressures, heat, gases, and fires along all of a defined circuit over time using an iterative procedure to solve Kirchhoff’s current law). Furthermore, in this study, it is illustrated how the joint numerical modeling of the ventilation circuit and fire, when applied to an underground gypsum mine in the northwest of Italy, provides all the elements necessary to define the safety procedures that should be adopted in standard conditions as well as during an emergency due to a fire. More specifically, it was possible to identify suitable escape routes depending on the location of the possible fire and the time available for the staff to be able to evacuate safely. Full article

(This article belongs to the Topic Recent Advances in Structural Health Monitoring)

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12 pages, 2390 KiB

Open AccessArticle

Fabrication of Temperature Sensors with High-Performance Uniformity through Thermal Annealing

by Hongrui Liu, Yongchun Li, Weiji Xie, Xinyi Zhou, Jishuang Hong, Junfeng Liang, Yanghui Liu, Wei Li and Hong Wang

Materials 2023, 16(4), 1491; https://doi.org/10.3390/ma16041491 - 10 Feb 2023

Viewed by 1529

Abstract

It is considered to be of great significance to monitor human health and track the effect of drugs by measuring human temperature mapping through flexible temperature sensors. In this work, we found that the thermal annealing of flexible temperature sensors based on graphite–acrylate [...] Read more.

It is considered to be of great significance to monitor human health and track the effect of drugs by measuring human temperature mapping through flexible temperature sensors. In this work, we found that the thermal annealing of flexible temperature sensors based on graphite–acrylate copolymer composites can not only improve the temperature coefficient of resistance (TCR) values of the devices, but also greatly improve the uniformity of the performance of the devices prepared in parallel. The best results were obtained when the devices were annealed at 100 °C, which is believed to be due to the rearrangement of graphite particles to generate more uniform and numerous conductive channels within the conductive composite. We believe this finding might promote the practical development of flexible temperature sensors in body temperature sensing for health maintenance and medical applications. Full article

(This article belongs to the Topic Recent Advances in Structural Health Monitoring)

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17 pages, 8025 KiB

Open AccessArticle

Structural Stability Monitoring of Model Test on Highway Tunnel with Lining Backside Voids Using Dynamic and Static Strain Testing Sensors

by Chaofei Du, Chuanbo Zhou, Nan Jiang and Yiwen Huang

Sensors 2023, 23(3), 1403; https://doi.org/10.3390/s23031403 - 26 Jan 2023

Cited by 1 | Viewed by 1419

Abstract

Voids behind a lining may develop due to insufficient backfilling, poor workmanship, water erosion or gravity. They affect the interaction between the surrounding rock and lining and even cause instability of the lining structure. To ensure the safe operation of tunnels, it is [...] Read more.

Voids behind a lining may develop due to insufficient backfilling, poor workmanship, water erosion or gravity. They affect the interaction between the surrounding rock and lining and even cause instability of the lining structure. To ensure the safe operation of tunnels, it is very important to study the influence of voids behind the lining of the lining structure. In this paper, a laboratory model of a tunnel lining was established by taking the voids behind the lining of the Wushan Tunnel as an example. By changing the position and size of the voids, the corresponding stress variation law of the lining was obtained, and the influence of the voids behind the lining on the structural stability of the highway tunnel was analyzed. The experimental results showed that the voids behind the lining led to an increase in the stress near the voids, especially the voids at the vault. The circumferential stress and axial stress increased with increasing void depth and length, and the increase was greater with increasing void depth than increasing length; that is, the void depth had a greater effect on the lining stress. When the vault void depth was 30 mm, the axial tensile stress of the vault was 0.281 MPa, and the maximum increase was 178.2% compared with that without voids. The safety factors at different lining positions, from large to small, are: arch foot > spinner > arch top > arch waist. In the processes of lining operation and maintenance, special attention should be given to the treatment of voids behind the lining, especially deep voids. Full article

(This article belongs to the Topic Recent Advances in Structural Health Monitoring)

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24 pages, 6914 KiB

Open AccessArticle

Effect of Environmental Parameters on Structural Health Status Assessment Using OMA Techniques

by Gabriele Bertagnoli, Mario Ferrara, Francescantonio Lucà and Alfredo Cigada

Appl. Sci. 2023, 13(3), 1477; https://doi.org/10.3390/app13031477 - 22 Jan 2023

Viewed by 1817

Abstract

The data from a laboratory test on two aluminum rods are analyzed in this work. The rods are subjected to environmental excitation in an uncontrolled environment, attempting to replicate real operational conditions of structural health monitoring with external disturbances. Different damage levels are [...] Read more.

The data from a laboratory test on two aluminum rods are analyzed in this work. The rods are subjected to environmental excitation in an uncontrolled environment, attempting to replicate real operational conditions of structural health monitoring with external disturbances. Different damage levels are simulated on one of the two tension rods. Three of the most frequently used OMA methods are applied to evaluate the effects of the simulated damage on the dynamic behavior of the system. The complexity of the three applied OMA methods is gradually increased. The difference between the results from the different approaches is assessed. The aim of this work is to assess the performance of the proposed OMA methods, to understand their limits, and to assess the role of environmental disturbance parameters, such as temperature, in the evaluation of the health status of structures. Full article

(This article belongs to the Topic Recent Advances in Structural Health Monitoring)

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40 pages, 6269 KiB

Open AccessFeature PaperArticle

Ultrasonic Attenuation of Ceramic and Inorganic Materials Using the Through-Transmission Method

by Kanji Ono

Appl. Sci. 2022, 12(24), 13026; https://doi.org/10.3390/app122413026 - 19 Dec 2022

Cited by 5 | Viewed by 2011

Abstract

Ultrasonic attenuation coefficients of ceramic and inorganic materials were determined for the longitudinal and transverse wave modes. Sample materials included hard and soft ceramics, common ceramics, ceramic-matrix composites, mortars, silicate glasses, rocks, minerals and crystals. For ceramic attenuation measurements, a standardized method has [...] Read more.

Ultrasonic attenuation coefficients of ceramic and inorganic materials were determined for the longitudinal and transverse wave modes. Sample materials included hard and soft ceramics, common ceramics, ceramic-matrix composites, mortars, silicate glasses, rocks, minerals and crystals. For ceramic attenuation measurements, a standardized method has existed, but this method based on a buffer-rod arrangement was found to be inconsistent, producing vastly different results. Resonant ultrasound spectroscopy was also found to be unworkable from its sample preparation requirements. Experimental reevaluation of the buffer-rod method showed its impracticality due to unpredictable reflectivity parameters, yielding mostly negative attenuation coefficients. In this work, attenuation tests relied on a through-transmission method, which incorporated a correction procedure for diffraction losses. Attenuation exhibited four types of frequency (f) dependence, i.e., linear, linear plus f⁴ (called Mason-McSkimin relation), f² and f³. The first two types were the most often observed. Elastic constants of tested materials were also tabulated, including additional samples too small for attenuation tests. Observed levels of attenuation coefficients will be useful for designing test methods for ultrasonic nondestructive evaluation and trends on ultrasonic attenuation are discussed in terms of available theories. However, many aspects of experimental findings remain unexplained and require future theoretical developments and detailed microstructural characterization. This study discovered a wide range of attenuation behaviors, indicating that the attenuation parameter can aid in characterizing the condition of intergranular boundaries in combination with imaging studies. Full article

(This article belongs to the Topic Recent Advances in Structural Health Monitoring)

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10 pages, 4736 KiB

Open AccessArticle

Characterization of Ductile Crack Propagation by Fractal Energy Dissipation Rate

by Yunfeng Zhao, Yangyang Zhao, Giuseppe Lacidogna, Baoming Gong and Sheng Wang

Appl. Sci. 2022, 12(23), 12388; https://doi.org/10.3390/app122312388 - 03 Dec 2022

Viewed by 1050

Abstract

Because of its geometry dependence and loss of physical meaning, the incremental crack resistance curve cannot characterize ductile fractures with large crack extensions and plastic deformations. Therefore, the energy dissipation rate R is employed to overcome these deficiencies, even though specimen size effects [...] Read more.

Because of its geometry dependence and loss of physical meaning, the incremental crack resistance curve cannot characterize ductile fractures with large crack extensions and plastic deformations. Therefore, the energy dissipation rate R is employed to overcome these deficiencies, even though specimen size effects still exist. In the study, considering the fractal crack path and concomitant plastic dissipation in the fractal domain, a scale-invariant energy dissipation rate, γ_p*, is proposed in the context of renormalization group theory. Some experiments in the literature have validated this approach. The fitted fractal energy dissipation rate is independent of the specimen size and initial crack length; moreover, as the specimen size increases, progressive fractality vanishing is found consistently with geometrical multifractality. Full article

(This article belongs to the Topic Recent Advances in Structural Health Monitoring)

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17 pages, 16574 KiB

Open AccessArticle

Fatigue Characteristics of 7050-T7451 Aluminum Alloy Friction Stir Welding Joints and the Stress Ratio Effect

by Hanji Zhu, Giuseppe Lacidogna, Caiyan Deng, Baoming Gong and Fei Liu

Materials 2022, 15(22), 8010; https://doi.org/10.3390/ma15228010 - 13 Nov 2022

Viewed by 1706

Abstract

The fatigue crack initiation and growth characteristics in 7050-T7451 aluminum alloy butt joints subjected to different stress ratios and owing to friction stir welding (FSW) were investigated using fatigue tests for stress ratios of 0.1, 0.3, and 0.5. The difference between the fatigue [...] Read more.

The fatigue crack initiation and growth characteristics in 7050-T7451 aluminum alloy butt joints subjected to different stress ratios and owing to friction stir welding (FSW) were investigated using fatigue tests for stress ratios of 0.1, 0.3, and 0.5. The difference between the fatigue crack initiation in the base material (BM) and FSW joints, related to coarse secondary phases, was explored using scanning electron microscopy (SEM). Accordingly, Al₂₃CuFe₄, Al₇Cu₂Fe, and Al₂Mg₃Zn₃ were the preferred joint crack initiation locations, whereas Mg₂Si was the major fracture initiation point of the parent material, and cracks tended to propagate along dense, coarse secondary phases, becoming more pronounced for larger cracks. In addition, as the stress ratio increased, non-Mg₂Si phase fracture initiation points appeared in the BM. Meanwhile, the quantity of non-Mg₂Si phases in the joints continued to increase, and the crack initiation sites became increasingly concentrated in the TMAZ-HAZ region. Full article

(This article belongs to the Topic Recent Advances in Structural Health Monitoring)

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23 pages, 7166 KiB

Open AccessArticle

Use of Chipless RFID as a Passive, Printable Sensor Technology for Aerospace Strain and Temperature Monitoring

by Kevin Mc Gee, Prince Anandarajah and David Collins

Sensors 2022, 22(22), 8681; https://doi.org/10.3390/s22228681 - 10 Nov 2022

Cited by 2 | Viewed by 2379

Abstract

This paper was concerned with the current level of progress towards the development of chipless radio frequency identification (RFID) sensors that are capable of sensing strain and temperature. More specifically, it was interested in the possibility that the resulting devices could be used [...] Read more.

This paper was concerned with the current level of progress towards the development of chipless radio frequency identification (RFID) sensors that are capable of sensing strain and temperature. More specifically, it was interested in the possibility that the resulting devices could be used as a passive wireless structural health monitoring (SHM) sensor technology that could be printed in situ. This work contains the development and performance characterization results for both novel strain and novel temperature sensor designs with resulting sensitivities of 9.77 MHz/%ε and 0.88 MHz/°C, respectively. Furthermore, a detailed discussion on the interrogation system required to meet the relevant aerospace sensing requirements was also discussed, and several methods were explored to enhance the multi-sensor support capabilities of this technology. Full article

(This article belongs to the Topic Recent Advances in Structural Health Monitoring)

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13 pages, 7062 KiB

Open AccessArticle

Localization of Cracks in Concrete Structures Using an Unmanned Aerial Vehicle

by Hyun-Jung Woo, Dong-Min Seo, Min-Seok Kim, Min-San Park, Won-Hwa Hong and Seung-Chan Baek

Sensors 2022, 22(17), 6711; https://doi.org/10.3390/s22176711 - 05 Sep 2022

Cited by 10 | Viewed by 2133

Abstract

Active research on crack detection technology for structures based on unmanned aerial vehicles (UAVs) has attracted considerable attention. Most of the existing research on localization of cracks using UAVs mounted the Global Positioning System (GPS)/Inertial Measurement Unit (IMU) on the UAVs to obtain [...] Read more.

Active research on crack detection technology for structures based on unmanned aerial vehicles (UAVs) has attracted considerable attention. Most of the existing research on localization of cracks using UAVs mounted the Global Positioning System (GPS)/Inertial Measurement Unit (IMU) on the UAVs to obtain location information. When such absolute position information is used, several studies confirmed that positioning errors of the UAVs were reflected and were in the order of a few meters. To address these limitations, in this study, without using the absolute position information, localization of cracks was defined using relative position between objects in UAV-captured images to significantly reduce the error level. Through aerial photography, a total of 97 images were acquired. Using the point cloud technique, image stitching, and homography matrix algorithm, 5 cracks and 3 reference objects were defined. Importantly, the comparative analysis of estimated relative position values and ground truth values through field measurement revealed that errors in the range 24–84 mm and 8–48 mm were obtained on the x- and y-directions, respectively. Also, RMSE errors of 37.95–91.24 mm were confirmed. In the future, the proposed methodology can be utilized for supplementing and improving the conventional methods for visual inspection of infrastructures and facilities. Full article

(This article belongs to the Topic Recent Advances in Structural Health Monitoring)

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26 pages, 3960 KiB

Open AccessReview

A Review of Vision-Laser-Based Civil Infrastructure Inspection and Monitoring

by Huixing Zhou, Chongwen Xu, Xiuying Tang, Shun Wang and Zhongyue Zhang

Sensors 2022, 22(15), 5882; https://doi.org/10.3390/s22155882 - 06 Aug 2022

Cited by 16 | Viewed by 3706

Abstract

Structural health and construction security are important problems in civil engineering. Regular infrastructure inspection and monitoring methods are mostly performed manually. Early automatic structural health monitoring techniques were mostly based on contact sensors, which usually are difficult to maintain in complex infrastructure environments. [...] Read more.

Structural health and construction security are important problems in civil engineering. Regular infrastructure inspection and monitoring methods are mostly performed manually. Early automatic structural health monitoring techniques were mostly based on contact sensors, which usually are difficult to maintain in complex infrastructure environments. Therefore, non-contact infrastructure inspection and monitoring techniques received increasing interest in recent years, and they are widely used in all aspects of infrastructure life, owing to their convenience and non-destructive properties. This paper provides an overview of vision-based inspection and vision–laser-based monitoring techniques and applications. The inspection part includes image-processing algorithms, object detection, and semantic segmentation. In particular, infrastructure monitoring involves not only visual technologies but also different fusion methods of vision and lasers. Furthermore, the most important challenges for future automatic non-contact inspections and monitoring are discussed and the paper correspondingly concludes with state-of-the-art algorithms and applications to resolve these challenges. Full article

(This article belongs to the Topic Recent Advances in Structural Health Monitoring)

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14 pages, 5360 KiB

Open AccessArticle

Non-Contact Hand Movement Analysis for Optimal Configuration of Smart Sensors to Capture Parkinson’s Disease Hand Tremor

by Prashanna Khwaounjoo, Gurleen Singh, Sophie Grenfell, Burak Özsoy, Michael R. MacAskill, Tim J. Anderson and Yusuf O. Çakmak

Sensors 2022, 22(12), 4613; https://doi.org/10.3390/s22124613 - 18 Jun 2022

Cited by 6 | Viewed by 2267

Abstract

Parkinson’s disease affects millions worldwide with a large rise in expected burden over the coming decades. More easily accessible tools and techniques to diagnose and monitor Parkinson’s disease can improve the quality of life of patients. With the advent of new wearable technologies [...] Read more.

Parkinson’s disease affects millions worldwide with a large rise in expected burden over the coming decades. More easily accessible tools and techniques to diagnose and monitor Parkinson’s disease can improve the quality of life of patients. With the advent of new wearable technologies such as smart rings and watches, this is within reach. However, it is unclear what method for these new technologies may provide the best opportunity to capture the patient-specific severity. This study investigates which locations on the hand can be used to capture and monitor maximal movement/tremor severity. Using a Leap Motion device and custom-made software the volume, velocity, acceleration, and frequency of Parkinson’s (n = 55, all right-handed, majority right-sided onset) patients’ hand locations (25 joints inclusive of all fingers/thumb and the wrist) were captured simultaneously. Distal locations of the right hand, i.e., the ends of fingers and the wrist showed significant trends (p < 0.05) towards having the largest movement velocities and accelerations. The right hand, compared with the left hand, showed significantly greater volumes, velocities, and accelerations (p < 0.01). Supplementary analysis showed that the volumes, acceleration, and velocities had significant correlations (p < 0.001) with clinical MDS-UPDRS scores, indicating the potential suitability of using these metrics for monitoring disease progression. Maximal movements at the distal hand and wrist area indicate that these locations are best suited to capture hand tremor movements and monitor Parkinson’s disease. Full article

(This article belongs to the Topic Recent Advances in Structural Health Monitoring)

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14 pages, 6202 KiB

Open AccessCommunication

Real-Time Structural Health Monitoring and Damage Identification Using Frequency Response Functions along with Finite Element Model Updating Technique

by Tarunpreet Singh, Shankar Sehgal, Chander Prakash and Saurav Dixit

Sensors 2022, 22(12), 4546; https://doi.org/10.3390/s22124546 - 16 Jun 2022

Cited by 13 | Viewed by 3184

Abstract

Throughout service, damage can arise in the structure of buildings; hence, their dynamic testing becomes essential to verify that such buildings possess sufficient strength to withstand disturbances, particularly in the event of an earthquake. Dynamic testing, being uneconomical, requires proof of concept; for [...] Read more.

Throughout service, damage can arise in the structure of buildings; hence, their dynamic testing becomes essential to verify that such buildings possess sufficient strength to withstand disturbances, particularly in the event of an earthquake. Dynamic testing, being uneconomical, requires proof of concept; for this, a model of a structure can be dynamically tested, and the results are used to update its finite element model. This can be used for damage detection in the prototype and aids in predicting its behavior during an earthquake. In this instance, a wireless MEMS accelerometer was used, which can measure the vibration signals emanating from the building and transfer these signals to a remote workstation. The base of the structure is excited using a shaking table to induce an earthquake-like situation. Four natural frequencies have been considered and six different types of damage conditions have been identified in this work. For each damage condition, the experimental responses are measured and the finite element model is updated using the Berman and Nagy method. It is seen that the updated models can predict the dynamic responses of the building accurately. Thus, depending on these responses, the damage condition can be identified by using the updated finite element models. Full article

(This article belongs to the Topic Recent Advances in Structural Health Monitoring)

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23 pages, 10321 KiB

Open AccessArticle

Investigation of Interlaminar Shear Properties of CFRP Composites at Elevated Temperatures Using the Lempel-Ziv Complexity of Acoustic Emission Signals

by Claudia Barile, Caterina Casavola, Giovanni Pappalettera, Vimalathithan Paramsamy Kannan and Gilda Renna

Materials 2022, 15(12), 4252; https://doi.org/10.3390/ma15124252 - 15 Jun 2022

Cited by 6 | Viewed by 1601

Abstract

Three-point bending tests on Short Beam Shear (SBS) specimens are performed to investigate the interlaminar shear properties of plain weave fabric CFRP composites. The tests are performed in a controlled environmental chamber at two different elevated temperatures. The interlaminar shear properties of the [...] Read more.

Three-point bending tests on Short Beam Shear (SBS) specimens are performed to investigate the interlaminar shear properties of plain weave fabric CFRP composites. The tests are performed in a controlled environmental chamber at two different elevated temperatures. The interlaminar shear properties of the specimens remain largely unaffected by the testing temperature. However, the SEM micrographs show different damage progressions between the specimens tested at 100 °C and 120 °C. Fibre ruptures and longer delamination between the plies, as a result of a high temperature, are observed in the specimens tested at 120 °C, which are not observed in the specimens tested at 100 °C. In addition, the acoustic emission activities during the tests are investigated by using piezoelectric sensors. The information-theoretic parameter, the Lempel-Ziv (LZ) complexity, is calculated for the recorded acoustic signals. The LZ Complexities are used for identifying the occurrence of the first delamination failure in the specimens. Additionally, the two features of the acoustic signals, LZ complexity and Weighted Peak Frequency (W.P-Freq), are used for distinguishing the different damage sources in the CFRP specimens. The results are well-supported by the time-frequency analysis of the acoustic signals using a Continuous Wavelet Transform (CWT). Full article

(This article belongs to the Topic Recent Advances in Structural Health Monitoring)

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14 pages, 2294 KiB

Open AccessArticle

Damage Diagnosis of Single-Layer Latticed Shell Based on Temperature-Induced Strain under Bayesian Framework

by Jie Xu, Zhengyang Zhao, Qian Ma, Ming Liu and Giuseppe Lacidogna

Sensors 2022, 22(11), 4251; https://doi.org/10.3390/s22114251 - 02 Jun 2022

Cited by 1 | Viewed by 1368

Abstract

Under the framework of Bayesian theory, a probabilistic method for damage diagnosis of latticed shell structures based on temperature-induced strain is proposed. First, a new damage diagnosis index is proposed based on the correlation between temperature-induced strain and structural parameters. Then, Markov Chain [...] Read more.

Under the framework of Bayesian theory, a probabilistic method for damage diagnosis of latticed shell structures based on temperature-induced strain is proposed. First, a new damage diagnosis index is proposed based on the correlation between temperature-induced strain and structural parameters. Then, Markov Chain Monte Carlo is adopted to analyze the newly proposed diagnosis index, based on which the frequency distribution histogram for the posterior probability of the diagnosis index is obtained. Finally, the confidence interval of the damage diagnosis is determined by the posterior distribution of the initial state (baseline condition). The damage probability of the unknown state is also calculated. The proposed method was validated by applying it to a latticed shell structure with finite element developed, where the rod damage and bearing failure were diagnosed based on importance analysis and temperature sensitivity analysis of the rod. The analysis results show that the proposed method can successfully consider uncertainties in the strain response monitoring process and effectively diagnose the failure of important rods in radial and annular directions, as well as horizontal (x- and y-direction) bearings of the latticed shell structure. Full article

(This article belongs to the Topic Recent Advances in Structural Health Monitoring)

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15 pages, 1300 KiB

Open AccessArticle

Application of Sensor Path Weighting RAPID Algorithm on Pitting Corrosion Monitoring of Aluminum Plate

by Duo Xu, Weifang Zhang, Lu Han, Xuerong Liu and Weiwei Hu

Materials 2022, 15(11), 3887; https://doi.org/10.3390/ma15113887 - 30 May 2022

Cited by 1 | Viewed by 1613

Abstract

Aluminum alloy is widely used in aerospace structures. However, it often suffers from a harsh corrosion environment, resulting in different damage such as pitting corrosion, which leads to a reduction in the service life of aerospace structures. In the present study, the pitting [...] Read more.

Aluminum alloy is widely used in aerospace structures. However, it often suffers from a harsh corrosion environment, resulting in different damage such as pitting corrosion, which leads to a reduction in the service life of aerospace structures. In the present study, the pitting corrosion with a radius of 1 mm and a depth of 0.6 mm was manufactured using hydrofluoric (HF) acid on a 2024-T3 aluminum alloy plate (400 mm × 400 mm × 2 mm) to simulate the corrosion state of equipment. A signal acquisition system with a square sensor network of 12 piezoelectric transducers (PZTs) was established. The sensor path weighting reconstruction algorithm for the probabilistic inspection of defects (SPW-RAPID) is proposed based on corrosion damage characteristic parameters including signal correlation coefficient (SDC), root mean squared error (RMSE), and signal energy damage index (E1) to explore the monitoring efficacy of pitting corrosion. The sensor path weight w, which is the product of value coefficient a and impact factor l, is established to modify the corrosion damage characteristic parameters. The results indicate that the SPW-RAPID algorithm can improve the accuracy and clarity of image reconstruction results based on SDC, RMSE and E1, which can locate the pitting corrosion with a radius of 1 mm and a depth of 0.6 mm, and the positioning error is controlled within 0.1 mm. The research work may provide an available way to monitor tiny corrosion damage on an aluminum alloy structure. Full article

(This article belongs to the Topic Recent Advances in Structural Health Monitoring)

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20 pages, 1493 KiB

Open AccessArticle

BepFAMN: A Method for Linear B-Cell Epitope Predictions Based on Fuzzy-ARTMAP Artificial Neural Network

by Anthony F. La Marca, Robson da S. Lopes, Anna Diva P. Lotufo, Daniella C. Bartholomeu and Carlos R. Minussi

Sensors 2022, 22(11), 4027; https://doi.org/10.3390/s22114027 - 26 May 2022

Cited by 4 | Viewed by 1838

Abstract

The public health system is extremely dependent on the use of vaccines to immunize the population from a series of infectious and dangerous diseases, preventing the system from collapsing and millions of people dying every year. However, to develop these vaccines and effectively [...] Read more.

The public health system is extremely dependent on the use of vaccines to immunize the population from a series of infectious and dangerous diseases, preventing the system from collapsing and millions of people dying every year. However, to develop these vaccines and effectively monitor these diseases, it is necessary to use accurate diagnostic methods capable of identifying highly immunogenic regions within a given pathogenic protein. Existing experimental methods are expensive, time-consuming, and require arduous laboratory work, as they require the screening of a large number of potential candidate epitopes, making the methods extremely laborious, especially for application to larger microorganisms. In the last decades, researchers have developed in silico prediction methods, based on machine learning, to identify these markers, to drastically reduce the list of potential candidate epitopes for experimental tests, and, consequently, to reduce the laborious task associated with their mapping. Despite these efforts, the tools and methods still have low accuracy, slow diagnosis, and offline training. Thus, we develop a method to predict B-cell linear epitopes which are based on a Fuzzy-ARTMAP neural network architecture, called BepFAMN (B Epitope Prediction Fuzzy ARTMAP Artificial Neural Network). This was trained using a linear averaging scheme on 15 properties that include an amino acid ratio scale and a set of 14 physicochemical scales. The database used was obtained from the IEDB website, from which the amino acid sequences with the annotations of their positive and negative epitopes were taken. To train and validate the knowledge models, five-fold cross-validation and competition techniques were used. The BepiPred-2.0 database, an independent database, was used for the tests. In our experiment, the validation dataset reached sensitivity = 91.50%, specificity = 91.49%, accuracy = 91.49%, MCC = 0.83, and an area under the curve (AUC) ROC of approximately 0.9289. The result in the testing dataset achieves a significant improvement, with sensitivity = 81.87%, specificity = 74.75%, accuracy = 78.27%, MCC = 0.56, and AOC = 0.7831. These achieved values demonstrate that BepFAMN outperforms all other linear B-cell epitope prediction tools currently used. In addition, the architecture provides mechanisms for online training, which allow the user to find a new B-cell linear epitope, and to improve the model without need to re-train itself with the whole dataset. This fact contributes to a considerable reduction in the number of potential linear epitopes to be experimentally validated, reducing laboratory time and accelerating the development of diagnostic tests, vaccines, and immunotherapeutic approaches. Full article

(This article belongs to the Topic Recent Advances in Structural Health Monitoring)

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23 pages, 3907 KiB

Open AccessArticle

Nonsynchronous Rotor Blade Vibrations in Last Stage of 380 MW LP Steam Turbine at Various Condenser Pressures

by Romuald Rzadkowski, Pawel Troka, Jerzy Manerowski, Leszek Kubitz and Miroslaw Kowalski

Appl. Sci. 2022, 12(10), 4884; https://doi.org/10.3390/app12104884 - 11 May 2022

Cited by 10 | Viewed by 2647

Abstract

This paper presents an analysis of nonsynchronous rotor blade vibrations in the last stage of an LP steam turbine at various condenser pressures. The nonlinear least squares Levenberg–Marquardt method is used in a tip-timing analysis to determine nonsynchronous multimode rotor blade vibrations, which [...] Read more.

This paper presents an analysis of nonsynchronous rotor blade vibrations in the last stage of an LP steam turbine at various condenser pressures. The nonlinear least squares Levenberg–Marquardt method is used in a tip-timing analysis to determine nonsynchronous multimode rotor blade vibrations, which is a novelty. This is done with two sensors in the casing and a once-per-revolution sensor. The accuracy of the nonlinear least squares Levenberg–Marquardt multimode method is compared with the one-mode linear method. The algorithm is verified by comparing it with one-mode tip-timing methods for synchronous and nonsynchronous vibrations. The analysis shows that the rotor blades vibrate simultaneously with two modes in non-nominal conditions, which is also a novelty. The rotor frequencies are unchanged, although the blade vibration amplitudes vary, depending on the pressure in the condenser. Flutter does not appear in the last stage for the various condenser pressures and powers that were tested. Full article

(This article belongs to the Topic Recent Advances in Structural Health Monitoring)

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13 pages, 638 KiB

Open AccessArticle

Shaking Table Attached to Magnetorheological Damper: Simulation and Experiments for Structural Engineering

by Alessandro N. Vargas, João G. Raminelli, Marcio A. F. Montezuma, Aldemir Aparecido Cavalini Junior, Ricardo Breganon and Constantin F. Caruntu

Sensors 2022, 22(10), 3644; https://doi.org/10.3390/s22103644 - 10 May 2022

Viewed by 1838

Abstract

This paper details how to construct a small-scale shaking table attached to a magnetorheological (MR) damper. The motivation for this construction relies on the increasing interest in modeling the dynamics of MR dampers—MR dampers have been used in structures for safety reasons. To [...] Read more.

This paper details how to construct a small-scale shaking table attached to a magnetorheological (MR) damper. The motivation for this construction relies on the increasing interest in modeling the dynamics of MR dampers—MR dampers have been used in structures for safety reasons. To model the MR damper, we use the so-called ‘Dahl model’, which is useful to represent systems with a hysteresis. The Dahl model, validated through experimental data collected in a laboratory, was combined with a linear model to represent a two-story building. This two-story building model allows us to simulate the dynamics of that building when its floors are attached to MR dampers. By doing so, we can assess—through simulation—to what extent MR dampers can protect structures from vibrations. Using data from the ‘El Centro’ earthquake (1940), we can conclude that MR dampers have the potential to reduce the impact of earthquakes upon structures. This finding emphasizes the potential benefits of MR dampers for the safety of structures, which is a conclusion taken from the apparatus detailed in this paper. Full article

(This article belongs to the Topic Recent Advances in Structural Health Monitoring)

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18 pages, 15414 KiB

Open AccessArticle

Corroded Bolt Identification Using Mask Region-Based Deep Learning Trained on Synthesized Data

by Quoc-Bao Ta, Thanh-Canh Huynh, Quang-Quang Pham and Jeong-Tae Kim

Sensors 2022, 22(9), 3340; https://doi.org/10.3390/s22093340 - 27 Apr 2022

Cited by 11 | Viewed by 2535

Abstract

The performance of a neural network depends on the availability of datasets, and most deep learning techniques lack accuracy and generalization when they are trained using limited datasets. Using synthesized training data is one of the effective ways to overcome the above limitation. [...] Read more.

The performance of a neural network depends on the availability of datasets, and most deep learning techniques lack accuracy and generalization when they are trained using limited datasets. Using synthesized training data is one of the effective ways to overcome the above limitation. Besides, the previous corroded bolt detection method has focused on classifying only two classes, clean and fully rusted bolts, and its performance for detecting partially rusted bolts is still questionable. This study presents a deep learning method to identify corroded bolts in steel structures using a mask region-based convolutional neural network (Mask-RCNN) trained on synthesized data. The Resnet50 integrated with a feature pyramid network is used as the backbone for feature extraction in the Mask-RCNN-based corroded bolt detector. A four-step data synthesis procedure is proposed to autonomously generate the training datasets of corroded bolts with different severities. Afterwards, the proposed detector is trained by the synthesized datasets, and its robustness is demonstrated by detecting corroded bolts in a lab-scale steel structure under varying capturing distances and perspectives. The results show that the proposed method has detected corroded bolts well and identified their corrosion levels with the most desired overall accuracy rate = 96.3% for a 1.0 m capturing distance and 97.5% for a 15° perspective angle. Full article

(This article belongs to the Topic Recent Advances in Structural Health Monitoring)

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18 pages, 8332 KiB

Open AccessArticle

Three-Level Distributed Real-Time Monitoring of Construction near Underground Infrastructure Using a Combined Intelligent Method

by Biao Zhou, Yingbin Gui, Xiaojian Wang and Xiongyao Xie

Sensors 2022, 22(9), 3260; https://doi.org/10.3390/s22093260 - 24 Apr 2022

Cited by 1 | Viewed by 1683

Abstract

With the rapid development of underground infrastructure and the uncertainty of its location, the possibility of damage due to nearby construction has increased. Thus, for the early warning of dangerous construction behaviors around underground facilities, this paper proposes a novel real-time distributed monitoring [...] Read more.

With the rapid development of underground infrastructure and the uncertainty of its location, the possibility of damage due to nearby construction has increased. Thus, for the early warning of dangerous construction behaviors around underground facilities, this paper proposes a novel real-time distributed monitoring method with three levels, comprised of the terminal node, relay node, and server. Corresponding to these three monitoring levels, a vibration-based intelligent solution for recognizing the construction source is presented and compared with the traditional method. First, the blind source separation method was used to separate collected signals into a limited number of monitoring object sources; this helped to minimize the number of required classification categories and reduce the recognition uncertainty caused by signal mixing. Then, the mutual information (MI) method was used to select suitable vibration features, which were used as the input matrix for the resulting intelligent recognition. Finally, the construction behaviors were identified at the server based on returned features. Guided by this method, a sample dataset including pile-driving, train-operation, and environment-vibration signals was constructed and combined with a multi-layer perceptron (MLP) and a long short-term memory (LSTM) network. The effects of blind source separation and the MI method are discussed in depth in this paper. Full article

(This article belongs to the Topic Recent Advances in Structural Health Monitoring)

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24 pages, 7599 KiB

Open AccessArticle

Effect of Phase Fluctuation on the Proper Operation of Smart Gear Health Monitoring System

by Thanh-Tung Mac, Daisuke Iba, Yusuke Matsushita, Seiya Mukai, Nanako Miura, Arata Masuda and Ichiro Moriwaki

Sensors 2022, 22(9), 3231; https://doi.org/10.3390/s22093231 - 22 Apr 2022

Cited by 1 | Viewed by 1535

Abstract

A smart gear sensor system has been developed for the condition monitoring of gear. This system includes a smart gear—the operation gear and a monitoring antenna. The analysis of the return loss of the monitoring antenna magnetically coupled with the smart gear gives [...] Read more.

A smart gear sensor system has been developed for the condition monitoring of gear. This system includes a smart gear—the operation gear and a monitoring antenna. The analysis of the return loss of the monitoring antenna magnetically coupled with the smart gear gives the health condition of the gear. This research considers the effects of the distance and phase fluctuations between two components on the magnetic resonant return loss. The impacts of phase fluctuations include both static and high-speed conditions. Two experimental rigs have been built for the two cases. The coupling distance and static phase fluctuation are conducted via the first experimental rig. The second experimental rig performs both the coupling distance and phase fluctuation effect simultaneously while the smart gear rotates at high speed. During each test, the monitoring antenna return loss is captured thanks to a network analyzer. Analysis of the return loss data demonstrates that both the coupling distance and the change of the phase angle at the static condition and high speed have influenced the resonant return loss of the monitoring antenna. These findings are meaningful to the authors for evaluating and improving the accuracy of this gear health monitoring technique. Full article

(This article belongs to the Topic Recent Advances in Structural Health Monitoring)

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20 pages, 11424 KiB

Open AccessArticle

Ultrasonic Coda Wave Experiment and Simulation of Concrete Damage Process under Uniaxial Compression

by Yameng He, Lei Song, Keke Xue, Shukui Liu, Haipeng Li, Weihao Yang and Jiahui Huang

Buildings 2022, 12(5), 514; https://doi.org/10.3390/buildings12050514 - 20 Apr 2022

Cited by 3 | Viewed by 2086

Abstract

Using the coda wave interferometry (CWI) method to obtain the ultrasonic coda wave characteristics of loaded concrete is an important method to evaluate the mechanical response of concrete. In this paper, the ultrasonic coda wave characteristics of C40–C70 concrete specimens (four strengths of [...] Read more.

Using the coda wave interferometry (CWI) method to obtain the ultrasonic coda wave characteristics of loaded concrete is an important method to evaluate the mechanical response of concrete. In this paper, the ultrasonic coda wave characteristics of C40–C70 concrete specimens (four strengths of concrete) under uniaxial compression were tested by laboratory experiments. Furthermore, to clarify the relationship between the internal damage process of concrete and the change rate of coda wave velocity, an ultrasonic coda wave discrete element simulation model combined with digital image processing technology was established. The results show that the coda wave is very sensitive to small changes in the compressive damage to concrete, and the change in coda wave velocity can correspond to the development process of concrete damage. This research is conducive to a better understanding of the complex material behavior of compressive concrete and proves the feasibility of ultrasonic field simulation and processing by using numerical simulation images of concrete damage. Full article

(This article belongs to the Topic Recent Advances in Structural Health Monitoring)

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15 pages, 5482 KiB

Open AccessArticle

A Novel Elastomer-Based Inclinometer for Ultrasensitive Bridge Rotation Measurement

by De Zhou, Ningbo Wang, Chaofeng Fu, Chuanrui Guo and Yangping Zhao

Sensors 2022, 22(7), 2715; https://doi.org/10.3390/s22072715 - 01 Apr 2022

Cited by 1 | Viewed by 1824

Abstract

Bridge deformation consists of cross-section rotation and deflection, which are crucial parameters for bridge capacity evaluation and damage detection. The maximum value of deflection usually happens at mid-span while for rotation it happens at two-ends. Therefore, compared with deflection, rotation is more convenient [...] Read more.

Bridge deformation consists of cross-section rotation and deflection, which are crucial parameters for bridge capacity evaluation and damage detection. The maximum value of deflection usually happens at mid-span while for rotation it happens at two-ends. Therefore, compared with deflection, rotation is more convenient for in-situ measurement since the bridge pier can be the reference point. In this study, a high-precision inclinometer for bridge rotation measurement was conceptualized, designed, and validated. The proposed inclinometer converted the small rotation of bridge section into the deformation of an elastomer. Strain gauges were then utilized to measure the elastomer deformation and thus the bridge rotation can be obtained. The dimensions and modulus of the elastomer were designed and chosen based on the theoretical analysis. Characteristics of the inclinometer were calibrated in lab and in-situ experiments at an in-service bridge were conducted to validate its feasibility and robustness. Test results showed that the proposed inclinometer had excellent performance in resolution and accuracy, which indicate its great potential for future bridge health monitoring. Full article

(This article belongs to the Topic Recent Advances in Structural Health Monitoring)

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17 pages, 2126 KiB

Open AccessArticle

Field Evaluation and Calibration of Low-Cost Air Pollution Sensors for Environmental Exposure Research

by Jianwei Huang, Mei-Po Kwan, Jiannan Cai, Wanying Song, Changda Yu, Zihan Kan and Steve Hung-Lam Yim

Sensors 2022, 22(6), 2381; https://doi.org/10.3390/s22062381 - 19 Mar 2022

Cited by 13 | Viewed by 3331

Abstract

This paper seeks to evaluate and calibrate data collected by low-cost particulate matter (PM) sensors in different environments and using different aggregated temporal units (i.e., 5-s, 1-min, 10-min, 30 min intervals). We first collected PM concentrations (i.e., PM₁, PM_2.5, [...] Read more.

This paper seeks to evaluate and calibrate data collected by low-cost particulate matter (PM) sensors in different environments and using different aggregated temporal units (i.e., 5-s, 1-min, 10-min, 30 min intervals). We first collected PM concentrations (i.e., PM₁, PM_2.5, and PM₁₀) data in five different environments (i.e., indoor and outdoor of an office building, a train platform and lobby of a subway station, and a seaside location) in Hong Kong, using five AirBeam2 sensors as the low-cost sensors and a TSI DustTrak DRX Aerosol Monitor 8533 as the reference sensor. By comparing the collected PM concentrations, we found high linearity and correlation between the data reported by the AirBeam2 sensors in different environments. Furthermore, the results suggest that the accuracy and bias of the PM data reported by the AirBeam2 sensors are affected by rainy weather and environments with high humidity and a high level of hygroscopic salts (i.e., a seaside location). In addition, increasing the aggregation level of the temporal units (i.e., from 5-s to 30 min intervals) increases the correlation between the PM concentrations obtained by the AirBeam2 sensors, while it does not significantly improve the accuracy and bias of the data. Lastly, our results indicate that using a machine learning model (i.e., random forest) for the calibration of PM concentrations collected on sunny days generates better results than those obtained with multiple linear models. These findings have important implications for researchers when designing environmental exposure studies based on low-cost PM sensors. Full article

(This article belongs to the Topic Recent Advances in Structural Health Monitoring)

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11 pages, 9121 KiB

Open AccessArticle

Non-Destructive Testing for Cavity Damages in Automated Machines Based on Acoustic Emission Tomography

by Yueyuan Su, Longjun Dong and Zhongwei Pei

Sensors 2022, 22(6), 2201; https://doi.org/10.3390/s22062201 - 11 Mar 2022

Cited by 7 | Viewed by 2247

Abstract

Damage detection is important for the maintenance of automated machines. General non-destructive testing techniques require static equipment and complex analysis processes, which restricts the maintenance of automated machines. Therefore, this paper proposes an acoustic emission (AE) tomography method for detecting cavity damage in [...] Read more.

Damage detection is important for the maintenance of automated machines. General non-destructive testing techniques require static equipment and complex analysis processes, which restricts the maintenance of automated machines. Therefore, this paper proposes an acoustic emission (AE) tomography method for detecting cavity damage in automated machines, combining the fast sweeping method (FSM) and the limited-memory Broyden-Fletcher-Goldfarb-Shanno (L-BFGS) method. This approach overcomes the limitations of real-time AE detection for cavity damage in continuous and homogeneous materials. The proposed method has been applied in numerical and laboratory experiments to validate its feasibility. The results show that the inversed low-velocity regions correspond to the actual cavity regions, and the sources of cavity damage can be effectively detected. This paper provides a new perspective for AE testing technologies, and also lays the foundation for other non-destructive testing techniques, in terms of cavity damage detection. Full article

(This article belongs to the Topic Recent Advances in Structural Health Monitoring)

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18 pages, 4137 KiB

Open AccessArticle

Multi-Filter Clustering Fusion for Feature Selection in Rotating Machinery Fault Classification

by Solichin Mochammad, Yoojeong Noh, Young-Jin Kang, Sunhwa Park, Jangwoo Lee and Simon Chin

Sensors 2022, 22(6), 2192; https://doi.org/10.3390/s22062192 - 11 Mar 2022

Cited by 1 | Viewed by 1979

Abstract

In the fault classification process, filter methods that sequentially remove unnecessary features have long been studied. However, the existing filter methods do not have guidelines on which, and how many, features are needed. This study developed a multi-filter clustering fusion (MFCF) technique, to [...] Read more.

In the fault classification process, filter methods that sequentially remove unnecessary features have long been studied. However, the existing filter methods do not have guidelines on which, and how many, features are needed. This study developed a multi-filter clustering fusion (MFCF) technique, to effectively and efficiently select features. In the MFCF process, a multi-filter method combining existing filter methods is first applied for feature clustering; then, key features are automatically selected. The union of key features is utilized to find all potentially important features, and an exhaustive search is used to obtain the best combination of selected features to maximize the accuracy of the classification model. In the rotating machinery examples, fault classification models using MFCF were generated to classify normal and abnormal conditions of rotational machinery. The obtained results demonstrated that classification models using MFCF provide good accuracy, efficiency, and robustness in the fault classification of rotational machinery. Full article

(This article belongs to the Topic Recent Advances in Structural Health Monitoring)

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19 pages, 4100 KiB

Open AccessArticle

Combined Use of Cointegration Analysis and Robust Outlier Statistics to Improve Damage Detection in Real-World Structures

by Simone Turrisi, Emanuele Zappa and Alfredo Cigada

Sensors 2022, 22(6), 2177; https://doi.org/10.3390/s22062177 - 10 Mar 2022

Cited by 4 | Viewed by 2741

Abstract

Due to the need for controlling many ageing and complex structures, structural health monitoring (SHM) has become increasingly common over the past few decades. However, one of the main limitations for the implementation of continuous monitoring systems in real-world structures is the effect [...] Read more.

Due to the need for controlling many ageing and complex structures, structural health monitoring (SHM) has become increasingly common over the past few decades. However, one of the main limitations for the implementation of continuous monitoring systems in real-world structures is the effect that benign influences, such as environmental and operational variations (EOVs), have on damage sensitive features. These fluctuations may mask malign changes caused by structural damages, resulting in false structural condition assessment. When damage identification is implemented as novelty detection due to the lack of known damage states, outliers may be part of the data set as the result of the benign and malign factors mentioned above. Thanks to the developments in the field of robust outlier detection, the current paper presents a new data fusion method based on the use of cointegration and minimum covariance determinant estimator (MCD), which allows us to visualize and to classify outliers in SHM data, depending on their origin. To validate the effectiveness of this technique, the recent case study of the KW51 bridge has been considered, whose natural frequencies are subjected to variations due to both EOVs and a real structural change. Full article

(This article belongs to the Topic Recent Advances in Structural Health Monitoring)

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21 pages, 5263 KiB

Open AccessArticle

New Soil Stress Measurement Sensor Based on the Effect of Elastic Charging of Electrodes

by Mikhail Kuchumov and Sergej Evtushenko

Buildings 2022, 12(3), 327; https://doi.org/10.3390/buildings12030327 - 09 Mar 2022

Cited by 1 | Viewed by 2233

Abstract

The purpose of this work was to develop a prototype of a soil stress sensor using a new technique for converting mechanical quantities, with functions for measuring stress changes in soils emerging under the action of a dynamic load associated with earthworks using [...] Read more.

The purpose of this work was to develop a prototype of a soil stress sensor using a new technique for converting mechanical quantities, with functions for measuring stress changes in soils emerging under the action of a dynamic load associated with earthworks using construction machinery, impact of transport, underground explosions and earthquakes. The development is intended to solve problems in increasing the overall efficiency of monitoring buildings and structures and measurement accuracy. Within the framework of the study, the basic requirements for primary converters of mechanical quantities operating underground were formulated. The design solutions of such sensors, which affect the quality of the information received, have been evaluated. As a result of the study, a new effect of “elastic charging of the interfacial layer of a solid metal electrode” for measuring normal stress in soils was explored and proposed eligible for this purpose. Consequently it became possible to apply this new approach to developing the soil stress measurement sensor, including the creation of its functional scheme of operation, and selection of the hardware set, construction elements and materials taking into account the nature of sensor work. Eventually, laboratory experiments obtaining numerical characteristics were carried out. Full article

(This article belongs to the Topic Recent Advances in Structural Health Monitoring)

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20 pages, 6223 KiB

Open AccessArticle

Evaluation of Hydrogen Permeation into High-Strength Steel during Corrosion in Different Marine Corrosion Zones

by Yong Xu, Yanliang Huang, Fanfan Cai, Zhengquan Wang, Dongzhu Lu, Xiutong Wang and Lihui Yang

Appl. Sci. 2022, 12(6), 2785; https://doi.org/10.3390/app12062785 - 09 Mar 2022

Cited by 5 | Viewed by 2170

Abstract

Hydrogen permeation into high-strength steel during the corrosion process can deteriorate their mechanical properties, thus seriously threatening the safety of steel structures. However, the hydrogen permeation behavior of steels in corrosive marine environments is not well understood. In this study, the hydrogen permeation [...] Read more.

Hydrogen permeation into high-strength steel during the corrosion process can deteriorate their mechanical properties, thus seriously threatening the safety of steel structures. However, the hydrogen permeation behavior of steels in corrosive marine environments is not well understood. In this study, the hydrogen permeation behavior and mechanism of AISI 4135 steel in different marine corrosion zones was investigated for the first time using an in situ hydrogen permeation monitoring system via outdoor and indoor tests. The three-month outdoor hydrogen permeation test showed that the diffusible hydrogen content of the steels exposed to the marine atmospheric, splash, tidal and immersion zone was 3.15 × 10⁻³, 7.00 × 10⁻², 2.06 × 10⁻² and 3.33 × 10⁻² wt ppm, respectively. Meanwhile, results showed that the hydrogen permeation current density was positively correlated with the corrosion rate of the steel in the marine environments. This research is of great significance for guiding the safe application of high-strength steel in the marine environments. Full article

(This article belongs to the Topic Recent Advances in Structural Health Monitoring)

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17 pages, 1811 KiB

Open AccessArticle

Hand Pronation–Supination Movement as a Proxy for Remotely Monitoring Gait and Posture Stability in Parkinson’s Disease

by Yusuf Ozgur Cakmak, Can Olcek, Burak Ozsoy, Prashanna Khwaounjoo, Gunes Kiziltan, Hulya Apaydin, Aysegul Günduz, Ozgur Oztop Cakmak, Sibel Ertan, Yasemin Gursoy-Ozdemir and Didem Gokcay

Sensors 2022, 22(5), 1827; https://doi.org/10.3390/s22051827 - 25 Feb 2022

Cited by 2 | Viewed by 2599

Abstract

The Unified Parkinson’s Disease Rating Scale (UPDRS) is a subjective Parkinson’s Disease (PD) physician scoring/monitoring system. To date, there is no single upper limb wearable/non-contact system that can be used objectively to assess all UPDRS-III motor system subgroups (i.e., tremor (T), rigidity (R), [...] Read more.

The Unified Parkinson’s Disease Rating Scale (UPDRS) is a subjective Parkinson’s Disease (PD) physician scoring/monitoring system. To date, there is no single upper limb wearable/non-contact system that can be used objectively to assess all UPDRS-III motor system subgroups (i.e., tremor (T), rigidity (R), bradykinesia (B), gait and posture (GP), and bulbar anomalies (BA)). We evaluated the use of a non-contact hand motion tracking system for potential extraction of GP information using forearm pronation–supination (P/S) motion parameters (speed, acceleration, and frequency). Twenty-four patients with idiopathic PD participated, and their UPDRS data were recorded bilaterally by physicians. Pearson’s correlation, regression analyses, and Monte Carlo validation was conducted for all combinations of UPDRS subgroups versus motion parameters. In the 262,125 regression models that were trained and tested, the models within 1% of the lowest error showed that the frequency of P/S contributes to approximately one third of all models; while speed and acceleration also contribute significantly to the prediction of GP from the left-hand motion of right handed patients. In short, the P/S better indicated GP when performed with the non-dominant hand. There was also a significant negative correlation (with medium to large effect size, range: 0.3–0.58) between the P/S speed and the single BA score for both forearms and combined UPDRS score for the dominant hand. This study highlights the potential use of wearable or non-contact systems for forearm P/S to remotely monitor and predict the GP information in PD. Full article

(This article belongs to the Topic Recent Advances in Structural Health Monitoring)

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23 pages, 8759 KiB

Open AccessArticle

Long-Range Correlations and Natural Time Series Analyses from Acoustic Emission Signals

by Leandro Ferreira Friedrich, Édiblu Silva Cezar, Angélica Bordin Colpo, Boris Nahuel Rojo Tanzi, Mario Sobczyk, Giuseppe Lacidogna, Gianni Niccolini, Luis Eduardo Kosteski and Ignacio Iturrioz

Appl. Sci. 2022, 12(4), 1980; https://doi.org/10.3390/app12041980 - 14 Feb 2022

Cited by 9 | Viewed by 1874

Abstract

This work focuses on analyzing acoustic emission (AE) signals as a means to predict failure in structures. There are two main approaches that are considered: (i) long-range correlation analysis using both the Hurst (H) and the detrended fluctuation analysis (DFA) exponents, and (ii) [...] Read more.

This work focuses on analyzing acoustic emission (AE) signals as a means to predict failure in structures. There are two main approaches that are considered: (i) long-range correlation analysis using both the Hurst (H) and the detrended fluctuation analysis (DFA) exponents, and (ii) natural time domain (NT) analysis. These methodologies are applied to the data that were collected from two application examples: a glass fiber-reinforced polymeric plate and a spaghetti bridge model, where both structures were subjected to increasing loads until collapse. A traditional (AE) signal analysis was also performed to reference the study of the other methods. The results indicate that the proposed methods yield reliable indication of failure in the studied structures. Full article

(This article belongs to the Topic Recent Advances in Structural Health Monitoring)

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17 pages, 7269 KiB

Open AccessArticle

Continuous Lactate Monitoring System Based on Percutaneous Microneedle Array

by Ming-Nan Chien, Shih-Hao Fan, Chi-Huang Huang, Chien-Chen Wu and Jung-Tung Huang

Sensors 2022, 22(4), 1468; https://doi.org/10.3390/s22041468 - 14 Feb 2022

Cited by 10 | Viewed by 4790

Abstract

Lactate measurement is important in the fields of sports and medicine. Lactate accumulation can seriously affect an athlete’s performance. The most common problem caused by lactate accumulation in athletes is muscle soreness due to excessive exercise. Moreover, from a medical viewpoint, lactate is [...] Read more.

Lactate measurement is important in the fields of sports and medicine. Lactate accumulation can seriously affect an athlete’s performance. The most common problem caused by lactate accumulation in athletes is muscle soreness due to excessive exercise. Moreover, from a medical viewpoint, lactate is one of the main prognostic factors of sepsis. Currently, blood sampling is the most common approach to lactate measurement for lactate sensing, and continuous measurement is not available. In this study, a low-cost continuous lactate monitoring system (CLMS) is developed based on a percutaneous microneedle array that uses a three-electrode lactate sensor. The working electrode has an area of 10 mm × 6 mm, including a 3 × 3 array of stainless-steel microneedles. The length, width, and thickness of each needle are 1 mm, 0.44 mm, and 0.03 mm, respectively. The working electrode is then plated with gold, polyaniline, lactate enzyme, Nafion, and Poly(2-hydroxyethyl methacrylate) (poly HEMA). The reference electrode is a 2 × 1 array covered with AgCl, and the counter electrode is a 2 × 1 array plated with gold. The sensor is incorporated into the CLMS and connected to a smartphone application and the cloud. The CLMS was tested on 40 human subjects who rode indoor bicycles, starting at 100 W and increasing in steps of 25 W at intervals of 5 min until exhaustion. The data acquired from the app connected to the CLMS were analyzed to determine the subjects’ lactate response to exercise and the feasibility of assessing exercise performance and training exercise intensity by using the proposed system. Full article

(This article belongs to the Topic Recent Advances in Structural Health Monitoring)

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25 pages, 10796 KiB

Open AccessArticle

Automatic Detection of Real Damage in Operating Tie-Rods

by Francescantonio Lucà, Stefano Manzoni, Alfredo Cigada, Silvia Barella, Andrea Gruttadauria and Francesco Cerutti

Sensors 2022, 22(4), 1370; https://doi.org/10.3390/s22041370 - 10 Feb 2022

Cited by 6 | Viewed by 2011

Abstract

Many researchers have proposed vibration-based damage-detection approaches for continuous structural health monitoring. Translation to real applications is not always straightforward because the proposed methods have mostly been developed and validated in controlled environments, and they have not proven to be effective in detecting [...] Read more.

Many researchers have proposed vibration-based damage-detection approaches for continuous structural health monitoring. Translation to real applications is not always straightforward because the proposed methods have mostly been developed and validated in controlled environments, and they have not proven to be effective in detecting real damage when considering real scenarios in which environmental and operational variations are not controlled. This work was aimed to develop a fully-automated strategy to detect damage in operating tie-rods that only requires one sensor and that can be carried out without knowledge of physical variables, e.g., the axial load. This strategy was created by defining a damage feature based on tie-rod eigenfrequencies and developing a data-cleansing strategy that could significantly improve performance of outlier detection based on the Mahalanobis squared distance in real applications. Additionally, the majority of damage-detection algorithms presented in the literature related to structural health monitoring were validated in controlled environments considering simulated damage conditions. On the contrary, the approach proposed in this paper was shown to allow for the early detection of real damage associated with a corrosion attack under the effects of an intentionally uncontrolled environment. Full article

(This article belongs to the Topic Recent Advances in Structural Health Monitoring)

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13 pages, 5047 KiB

Open AccessArticle

A Novel Pulsed Eddy Current Criterion for Non-Ferromagnetic Metal Thickness Quantifications under Large Liftoff

by Haowen Wang, Jiangbo Huang, Longhuan Liu, Shanqiang Qin and Zhihong Fu

Sensors 2022, 22(2), 614; https://doi.org/10.3390/s22020614 - 13 Jan 2022

Cited by 11 | Viewed by 1820

Abstract

The pulsed eddy current (PEC) inspection is considered a versatile non-destructive evaluation technique, and it is widely used in metal thickness quantifications for structural health monitoring and target recognition. However, for non-ferromagnetic conductors covered with non-uniform thick insulating layers, there are still deficiencies [...] Read more.

The pulsed eddy current (PEC) inspection is considered a versatile non-destructive evaluation technique, and it is widely used in metal thickness quantifications for structural health monitoring and target recognition. However, for non-ferromagnetic conductors covered with non-uniform thick insulating layers, there are still deficiencies in the current schemes. The main purpose of this study is to find an effective feature, to measure wall thinning under the large lift-off variations, and further expand application of the PEC technology. Therefore, a novel method named the dynamic apparent time constant (D-ATC) is proposed based on the coil-coupling model. It associates the dynamic behavior of the induced eddy current with the geometric dimensions of the non-ferromagnetic metallic component by the time and amplitude features of the D-ATC curve. Numeral calculations and experiments show that the time signature is immune to large lift-off variations. Full article

(This article belongs to the Topic Recent Advances in Structural Health Monitoring)

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