Monitoring of Interfacial Debonding of Concrete Filled Pultrusion-GFRP Tubular Column Based on Piezoelectric Smart Aggregate and Wavelet Analysis

The concrete filled pultrusion-GFRP (Glass Fiber Reinforced Polymer) tubular column (CFGC) is popular in hydraulic structures or regions with poor environmental conditions due to its excellent corrosion resistance. Considering the influence of concrete hydration heat, shrinkage, and creep, debonding may occur in the interface between the GFRP tube and the concrete, which will greatly reduce the cooperation of the GFRP tube and concrete, and will weaken the mechanical property of CFGC. This paper introduces an active monitoring method based on the piezoelectric transducer. In the active sensing approach, the smart aggregate (SA) embedded in the concrete acted as a driver to transmit a modulated stress wave, and the PZT (Lead Zirconate Titanate) patches attached on the outer surface of CFGC serve as sensors to receive signals and transfer them to the computer for saving. Two groups of experiments were designed with the different debonding areas and thicknesses. The artificial damage of CFGC was identified and located by comparing the value of the delay under pulse excitation and the difference of wavelet-based energy under sweep excitation, and the damage indexes were defined based on the wavelet packet energy to quantify the level of the interface damage. The results showed that the debonding damage area of CFGC can be identified effectively through the active monitoring method, and the damage index can accurately reflect the damage level of the interface of GFRP tube and concrete. Therefore, this method can be used to identify and evaluate the interface debonding of CFGC in real time. In addition, if the method can be combined with remote sensing technology, it can be used as a real-time remote sensing monitoring technology to provide a solution for interface health monitoring of CFGC.

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Real-Time Monitoring of Timber-Surface Crack Repair Using Piezoelectric Ceramics

Journal of Sensors ◽

10.1155/2021/8201780 ◽

2021 ◽

Vol 2021 ◽

pp. 1-15

Author(s):

Huien Meng ◽

Wenwei Yang ◽

Xia Yang

Keyword(s):

Real Time ◽

Lead Zirconate Titanate ◽

Surface Crack ◽

Wavelet Packet ◽

Damage Index ◽

Piezoelectric Ceramics ◽

Strength Development ◽

Active Sensing ◽

Surface Cracks ◽

Crack Repair

Real-time assessment of timber-surface crack repair is crucial to the stability and safety of timber structures. Epoxy resin was used to repair timber cracks, and the active sensing technique using piezoelectric ceramics was applied to monitor the repair process of timber surface cracks in real time. Sixteen wood samples were designed for axial compression tests and active monitoring tests. A pair of lead zirconate titanate patches was pasted on the surface of the timber specimens as actuators and sensors for signal transmission and reception, through wavelet packet analysis, the variations in the signal amplitude, and wavelet coefficients. The relationship between the wavelet packet energy of the monitoring signal and the ultimate bearing capacity of the specimens at different periods after grouting was established. Based on the root-mean-square deviation, the damage index, DI, was introduced to evaluate the repair degree of timber surface cracks quantitatively. The results showed that the active sensing method can evaluate the strength development in timber-surface crack repair in real time.

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Dynamic Monitoring Method of Forest Coverage Based on GIS Technology

Global NEST Journal ◽

10.30955/gnj.003389 ◽

2020 ◽

Keyword(s):

Remote Sensing ◽

Real Time ◽

Average Energy ◽

Remote Sensing Image ◽

Model Management ◽

Dynamic Monitoring ◽

Likelihood Method ◽

Gis Technology ◽

Monitoring Method ◽

Forest Coverage

<p>When studying the dynamic monitoring method of forest coverage based on GIS technology, a dynamic monitoring system of forest coverage based on GIS technology was constructed, and forest coverage was dynamically monitored by means of the system. The system constructs attribute database and spatial database through RS data and topographic map, GPS measured data and GIS data, transfers data from the two databases to the quality supervision module for real-time query, early warning and evaluation of decision-making data quality, and transfers data that meets the quality requirements to the method management module and model in the data management module. In the model management module method, the management module uses geometric precise correction method to enhance remote sensing image, classifies and enhances remote sensing image by maximum likelihood method, calculates forest coverage by model management module according to classified remote sensing image on the basis of the method module, transmits the calculation results to the result database, updates the dynamic monitoring results in real time, and monitors them. The result is transmitted to the output module for output. The experimental results show that the average energy consumption for dynamic monitoring of forest cover is 324.09 J, and the monitoring results are consistent with the statistical results of the actual statistical yearbook.</p>

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Active Monitoring of Fatigue Crack in the Weld Zone of Bogie Frames Using Ultrasonic Guided Waves

Sensors ◽

10.3390/s19153372 ◽

2019 ◽

Vol 19 (15) ◽

pp. 3372 ◽

Cited By ~ 9

Author(s):

Yan ◽

Jin ◽

Sun ◽

Qing

Keyword(s):

Fatigue Crack ◽

Lead Zirconate Titanate ◽

Fatigue Cracks ◽

Weld Zone ◽

Damage Index ◽

Guided Wave ◽

Vertical Force ◽

Active Monitoring ◽

Bogie Frame ◽

Railway Vehicles

The bogie frame is an important structure of railway vehicles, transmitting the traction, braking force, lateral force, and vertical force during the traction operation. With the development of high speeds and heavy loads, the appearance of fatigue cracks in the bogie frames is increasing, which reduces the driving life of railway vehicles and even causes serious traffic accidents. Real-time monitoring on the integrity of the bogie is an inevitable requirement for ensuring the safe operation of railway vehicles. In this paper, ultrasonic guided wave-based active structural health monitoring (SHM) was developed to identify the fatigue crack of the bogie frame. Experiments were conducted on a welded T-shape specimen with a thickness of 12 mm. A total of 10 piezoelectric lead zirconate titanate (PZT) disks were mounted around the weld zone of the specimen, five of which were used as actuators, and the other five were used as sensors. Five-peak modulation narrow-band sine waves were input into the actuators to excite the specimen. From the sensor signals, the advanced damage index (DI) was calculated to identify the propagation of the crack. The experimental results demonstrate that crack damage as small as 2 mm in the weld zone of the bogie frame can be successfully detected. Some practical issues for implementing the SHM in real applications, such as crack quantification and environmental compensation, were also discussed.

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Experimental Study on Active Interface Debonding Detection for Rectangular Concrete-Filled Steel Tubes with Surface Wave Measurement

Sensors ◽

10.3390/s19153248 ◽

2019 ◽

Vol 19 (15) ◽

pp. 3248 ◽

Cited By ~ 5

Author(s):

Bin Xu ◽

Lele Luan ◽

Hongbing Chen ◽

Jiang Wang ◽

Wenting Zheng

Keyword(s):

Surface Wave ◽

Lead Zirconate Titanate ◽

Damage Index ◽

Steel Tube ◽

Interface Debonding ◽

Concrete Core ◽

Pzt Actuator ◽

Wave Measurement ◽

Detection Approach ◽

Debonding Detection

Concrete-filled steel tube (CFST) members have been widely employed as major structural members carrying axial or vertical loads and the interface bond condition between steel tube and concrete core plays key roles in ensuring the confinement effect of steel tube on concrete core. An effective interface debonding defect detection approach for CFSTs is critical. In this paper, an active interface debonding detection approach using surface wave measurement with a piezoelectric lead zirconate titanate (PZT) patch as sensor mounted on the outer surface of the CFST member excited with a PZT actuator mounted on the identical surface is proposed in order to avoid embedding PZT-based smart aggregates (SAs) in concrete core. In order to validate the feasibility of the proposed approach and to investigate the effect of interface debonding defect on the surface wave measurement, two rectangular CFST specimens with different degrees of interface debonding defects on three internal surfaces are designed and experimentally studied. Surface stress waves excited by the PZT actuator and propagating along the steel tube of the specimens are measured by the PZT sensors with a pitch and catch pattern. Results show that the surface-mounted PZT sensor measurement is sensitive to the existence of interface debonding defect and the interface debonding defect leads to the increase in the voltage amplitude of surface wave measurement. A damage index defined with the surface wave measurement has a linear relationship with the heights of the interface debonding defects.

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Application of Forest Health Monitoring Method in Assessing Tree Damage in Metro Urban Forests

Jurnal Sylva Lestari ◽

10.23960/jsl37289-298 ◽

2019 ◽

Vol 7 (3) ◽

pp. 289

Author(s):

Bondan Abimanyu ◽

Rahmat Safe’i ◽

Wahyu Hidayat

Keyword(s):

Health Monitoring ◽

Urban Forest ◽

Damage Index ◽

Forest Health ◽

Urban Forests ◽

Monitoring Method ◽

Tree Damage ◽

Damage Level ◽

Forest Health Monitoring ◽

Location Type

The assessment of tree condition is very important to ensure visitor safety and to maintain the sustainability of Metro Urban Forest. However, data and information on the condition of trees in six locations of Metro Urban Forest are not yet available. Therefore, this study was conducted to assess tree damage in each Metro Urban Forest. Evaluation of tree damage such as location, type, and level of tree damage was conducted for each tree in accordance with the damage criteria of the Forest Health Monitoring method. Data were then analyzed by calculating the damage index and tree damage level index. The results showed that the vegetation in Metro Urban Forests was dominated by trees with the healthy condition of 1.549 trees or 87% of the total trees, hence the Metro Urban Forests could be considered safe for visitors. The level of tree damage in each Metro Urban Forest is as follows: 3% in Islamic Center Urban Forest, 9% in Tesarigaga Urban Forest, 12% in Bumi Perkemahan Urban Forest, 13% in Linara Urban Forest, 23% in Terminal 16c Urban Forest, and 23% in Stadion Urban Forest at 23%. Overall tree damage in the Metro Urban Forest reached 232 trees or 13% of the total trees. Tree maintenance in each urban forest in Metro City is needed to maintain tree health, the safety of visitors, and improve the quality of the urban environment. Keywords: damaged trees, Forest Health Monitoring, Metro Urban Forests

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Power-Based Non-Intrusive Condition Monitoring for Terminal Device in Smart Grid

Sensors ◽

10.3390/s20133635 ◽

2020 ◽

Vol 20 (13) ◽

pp. 3635 ◽

Cited By ~ 1

Author(s):

Guoming Zhang ◽

Xiaoyu Ji ◽

Yanjie Li ◽

Wenyuan Xu

Keyword(s):

Smart Grid ◽

Power Consumption ◽

Real Time ◽

Condition Monitoring ◽

Resource Constraints ◽

Detection System ◽

Stable Operation ◽

Detection Accuracy ◽

Monitoring Method ◽

Dsp Processors

As a critical component in the smart grid, the Distribution Terminal Unit (DTU) dynamically adjusts the running status of the entire smart grid based on the collected electrical parameters to ensure the safe and stable operation of the smart grid. However, as a real-time embedded device, DTU has not only resource constraints but also specific requirements on real-time performance, thus, the traditional anomaly detection method cannot be deployed. To detect the tamper of the program running on DTU, we proposed a power-based non-intrusive condition monitoring method that collects and analyzes the power consumption of DTU using power sensors and machine learning (ML) techniques, the feasibility of this approach is that the power consumption is closely related to the executing code in CPUs, that is when the execution code is tampered with, the power consumption changes accordingly. To validate this idea, we set up a testbed based on DTU and simulated four types of imperceptible attacks that change the code running in ARM and DSP processors, respectively. We generate representative features and select lightweight ML algorithms to detect these attacks. We finally implemented the detection system on the windows and ubuntu platform and validated its effectiveness. The results show that the detection accuracy is up to 99.98% in a non-intrusive and lightweight way.

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