scholarly journals Corrosion Evaluation Using Clustering Method Based on Eddy Current Pulsed Thermography

Author(s):  
Peizhen Shi ◽  
Song Ding ◽  
Yuming Chen ◽  
Yiqing Wang ◽  
Guiyun Tian ◽  
...  

As a popular defect of steel, corrosion had been a big challenge to industry safe and structural health. For atmosphere corrosion characterization and evaluation, a clustering by fast search and find of density peaks (CFSFDP) algorithm, combined with gap statistic (GS) method is utilized to corroded Q235 carbon steel tubes. With the proposed method, three natural atmosphere corroded samples are investigated and classified. The proposed method successfully identifies the samples with different service periods. The temperature gradient, which indicates the heat generation and conductivity, is used to analyze cluster center selection. The matching rate is presented as a feature to reflect the corrosion state difference.

2022 ◽  
Vol 2022 ◽  
pp. 1-13
Author(s):  
Zhihe Wang ◽  
Yongbiao Li ◽  
Hui Du ◽  
Xiaofen Wei

Aiming at density peaks clustering needs to manually select cluster centers, this paper proposes a fast new clustering method with auto-select cluster centers. Firstly, our method groups the data and marks each group as core or boundary groups according to its density. Secondly, it determines clusters by iteratively merging two core groups whose distance is less than the threshold and selects the cluster centers at the densest position in each cluster. Finally, it assigns boundary groups to the cluster corresponding to the nearest cluster center. Our method eliminates the need for the manual selection of cluster centers and improves clustering efficiency with the experimental results.


2021 ◽  
Vol 10 (3) ◽  
pp. 161
Author(s):  
Hao-xuan Chen ◽  
Fei Tao ◽  
Pei-long Ma ◽  
Li-na Gao ◽  
Tong Zhou

Spatial analysis is an important means of mining floating car trajectory information, and clustering method and density analysis are common methods among them. The choice of the clustering method affects the accuracy and time efficiency of the analysis results. Therefore, clarifying the principles and characteristics of each method is the primary prerequisite for problem solving. Taking four representative spatial analysis methods—KMeans, Density-Based Spatial Clustering of Applications with Noise (DBSCAN), Clustering by Fast Search and Find of Density Peaks (CFSFDP), and Kernel Density Estimation (KDE)—as examples, combined with the hotspot spatiotemporal mining problem of taxi trajectory, through quantitative analysis and experimental verification, it is found that DBSCAN and KDE algorithms have strong hotspot discovery capabilities, but the heat regions’ shape of DBSCAN is found to be relatively more robust. DBSCAN and CFSFDP can achieve high spatial accuracy in calculating the entrance and exit position of a Point of Interest (POI). KDE and DBSCAN are more suitable for the classification of heat index. When the dataset scale is similar, KMeans has the highest operating efficiency, while CFSFDP and KDE are inferior. This paper resolves to a certain extent the lack of scientific basis for selecting spatial analysis methods in current research. The conclusions drawn in this paper can provide technical support and act as a reference for the selection of methods to solve the taxi trajectory mining problem.


2019 ◽  
Vol 84 (1) ◽  
pp. 9-20
Author(s):  
Xuhui Zhu ◽  
Junliang Shang ◽  
Yan Sun ◽  
Feng Li ◽  
Jin-Xing Liu ◽  
...  

Author(s):  
Adriana de Araujo ◽  
Claudia de Andrade Oliveira ◽  
Tatiana Regina da Silva Simão

abstract: The heritage of modern architecture in exposed reinforced concrete has been shown pathological manifestations affecting the structural safety and functionality of the buildings. The manifestations are, primarily, associated with the steel corrosion; however published data obtained from site surveys, on the Brazilian architectural heritage and related to the issue, are still scarce in the literature. Thus, the aim of the study is to assess the current condition of the exposed concrete façades reinforcement of the Vilanova Artigas building, a Brazilian architectural heritage, opened in 1969. Legal restrictions limited the destructive tests and sampling areas. The history of the interventions, environmental aggressiveness and preliminary inspection (in the parent concrete and patch repairs) provided qualified information for analyzing in situ testing results. In the sampling areas physical, chemical and electrochemical tests were carried out. The façades surfaces are naturally porous, irregular, with concrete segregation and corrosion products stains; 24% of the concrete was replaced with proprietary mortar repair. In patch repairs, the average carbonation depth ranged from 3 to 29 mm, in concrete it ranged from 15 to 30 mm. The reinforcement cover ranged from 8 to 33 mm. Corrosion potential maps, with equipotential lines drawn at 50 mV intervals, indicated the corrosion-prone areas, where there is a concentration of lines with a variation equal to or greater than 150 mV. The presence of corrosion products, detected in the visual examination of the reinforcement under the patch repairs, validated the active corrosion state. The rough surface of the concrete, the low cover to depassivated reinforcement and the active corrosion state emphasize the need for monitoring the façades and the urgency of implementing a preventive maintenance plan, along with a conservation project in order to preserve the heritage values of the building.


2020 ◽  
Vol 3 (2) ◽  
Author(s):  
Yuliana Yuliana ◽  
Mario Richie ◽  
Halim Agung

CV. Jaya Tunggal Keramik is a company that sale of ceramics. CV. Jaya Tunggal Keramik experienced some problems regarding ceramics and customers such as difficulties in sale ceramics to customers so that some ceramic products accumulate in the warehouse, such as being damaged and ceramic display becomes less good because it is stored too long and difficulty retaining customers because some customers do not want to order ceramic products. Lack of precise decision taken by the management CV. Jaya Tunggal Keramik in determining the strategy to supply ceramic and how to make it CV. Jaya Tunggal Keramik is difficult to estimate the stock of ceramic products to be provided and it is difficult to determine which potential customers can be maintained as a regular customer. This research uses K-Means algorithm. K-Means algorithm is a partitioning clustering method that separates data into different groups with iterative partitioning. By using this application, users can find out the estimated stock and price of ceramics as well as information about potential customers. Testing in this research using data of November 2017 that compared with data of December 2017. Based on ceramic data test results, there are some ceramics that are not in accordance with the predicted results so it can be concluded that the K-Means algorithm on the test inventory data inventory in this study is not fully can provide accurate estimates, this is because the use of the K-Means algorithm is strongly influenced by the cluster center results and the attributes used.


2018 ◽  
Vol 199 ◽  
pp. 04007 ◽  
Author(s):  
Gabriel Samson ◽  
Fabrice Deby ◽  
Jean-Luc Garciaz ◽  
Jean-Louis Perrin

The corrosion of steel rebars is a major issue with respect to the durability of reinforced concrete structure. Several corrosion evaluation methods exist: half-cell potential, concrete resistivity or linear polarization resistance (LPR) measurement. However, these techniques are employed at a given moment and are not suitable for continuous corrosion evaluation. This works belongs to the DIAMOND project which aims to produce a new corrosion state measurement monitoring device. The monitoring probe consists on a cylindrical probe. A ring shape counter-electrode CE is plated on the probe side. At the centre of the CE, a reference electrode (RE) is placed for potential measurement. The device is embedded in concrete at 25 mm of the inspected rebar. The instantaneous ohmic drop observed at the beginning of the polarization measurement is only linked with the concrete resistance which depends on concrete cover and resistivity. A numerical model was developed on Comsol® to create abacuses graph that link concrete resistivity and concrete resistance. Thus, the ohmic drop measure at the beginning of the polarization can now be used to determine regularly concrete average resistivity between the monitoring probe and steel rebar. Two other series of abacus graphs are then introduced in order to determine the polarization resistance of the rebar in front of the monitoring probe (the point of interest (PI)). Two monitoring probes were placed in two types of concrete (one sound concrete and one concrete with chloride). Corrosion potential, concrete resistivity and rebar corrosion rate were monitored over around 200 days. The experimental results obtained with the monitoring probe are finally compared to the results obtained with the surface DIAMOND probe (introduced in the ICCRRR 2018 paper “Alternative methodology for linear polarization resistance assessment of reinforced concrete structure [1]”).


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