scholarly journals Application of Thermal Image Data to Detect Rebar Corrosion in Concrete Structures

2019 ◽  
Vol 9 (21) ◽  
pp. 4700 ◽  
Author(s):  
Seunguk Na ◽  
Inkwan Paik
Keyword(s):  
Temperature Distribution ◽  
Distribution Curve ◽  
Concrete Structures ◽  
Electrochemical Corrosion ◽  
Detection Methods ◽  
Corrosion Monitoring ◽  
Rebar Corrosion ◽  
Infrared Cameras ◽  
Cover Thickness ◽  
The Impact

Rebar corrosion monitoring techniques have been used in studies involving embedded sensors that can detect changes in the corrosion currents and the polarization resistance of rebars in large structures. Defect detection methods that employ infrared cameras are useful non-destructive testing methods to detect defects in concrete structures. However, the measurement results from these methods would vary depending upon several factors that affect thermography. Because of these reasons, they have not been able to provide sufficient reliability. The goal of this study is to develop a technique that uses infrared cameras to quantitatively measure rebar corrosion rates. To examine the impact of the cover thickness, the experiment variables were set at cover thicknesses of 10, 20, and 30 mm and rebar corrosion ratios of 0%, 1%, 3%, 5%, 7%, and 10%. Each variable was tested and a total of 60 specimens were created (i.e., 54 specimens and 6 preliminary specimens). In this study, corrosion was applied using an electrochemical corrosion method that employs Faraday’s law, i.e., the law of conservation of electric charge. The test results of height, width, and area of temperature distribution curve were analyzed, the height of temperature distribution curve was increased as the heating time was grown. In addition, the area of temperature distribution was varied dependent upon the corrosion rate and cover thickness.

Evaluation of the corrosion potential in armed concrete as a function of armature covering

2021 ◽  
Author(s):  
Lázaro Rodrigues Penna ◽  
Maria Luísa Freitas dos Santos Honório ◽  
João Victor Laurindo Siqueira ◽  
Diogo Pereira dos Santos Kropf
Keyword(s):  
Corrosion Potential ◽  
Concrete Structures ◽  
Concrete Cover ◽  
Potential Range ◽  
Hardened Concrete ◽  
Corrosion Monitoring ◽  
Potential Measurement ◽  
External Agents ◽  
Cover Thickness ◽  
Corrosion Of Steel

In concrete structures, it is not uncommon to observe the presence of pathological problems that can often be associated with high temperature range, inadequate execution of works, inefficient projects, materials without quality control, unprepared labor, harmful external agents, among others. Among the pathological manifestations of hardened concrete is the corrosion of steel reinforcement, directly influencing the durability and strength of concrete structures. The object of this research is to analyze the influence of concrete cover thickness and chloride contamination on the potential readings of reinforcement corrosion. Since the cover thickness has a direct influence on the potential readings in chloride contaminated concrete. The corrosion potential measurement method will be used as an electrochemical tool to assist in the corrosion monitoring of reinforced concrete structures. As a standard for the evaluation results, the corrosion potential range recommended by ASTM C 876: 2015 and its relationship with the possibility of corrosion is normally used. With the results obtained during the application of this method, it is possible to identify regions where the reinforcement presents corrosion and how the process of steel depassivation is distributed in the region under study. Therefore, it is expected to verify the influence that the concrete cover has on chloride contamination and also influence the values of the corrosion potential.

scholarly journals A Systematic Review of Landsat Data for Change Detection Applications: 50 Years of Monitoring the Earth

2021 ◽  
Vol 13 (15) ◽  
pp. 2869
Author(s):  
MohammadAli Hemati ◽  
Mahdi Hasanlou ◽  
Masoud Mahdianpari ◽  
Fariba Mohammadimanesh
Keyword(s):  
Time Series ◽  
Change Detection ◽  
Policy Development ◽  
Atmospheric Correction ◽  
Open Data ◽  
Detection Methods ◽  
Landsat 8 ◽  
Landsat Images ◽  
Detection Analysis ◽  
The Impact

With uninterrupted space-based data collection since 1972, Landsat plays a key role in systematic monitoring of the Earth’s surface, enabled by an extensive and free, radiometrically consistent, global archive of imagery. Governments and international organizations rely on Landsat time series for monitoring and deriving a systematic understanding of the dynamics of the Earth’s surface at a spatial scale relevant to management, scientific inquiry, and policy development. In this study, we identify trends in Landsat-informed change detection studies by surveying 50 years of published applications, processing, and change detection methods. Specifically, a representative database was created resulting in 490 relevant journal articles derived from the Web of Science and Scopus. From these articles, we provide a review of recent developments, opportunities, and trends in Landsat change detection studies. The impact of the Landsat free and open data policy in 2008 is evident in the literature as a turning point in the number and nature of change detection studies. Based upon the search terms used and articles included, average number of Landsat images used in studies increased from 10 images before 2008 to 100,000 images in 2020. The 2008 opening of the Landsat archive resulted in a marked increase in the number of images used per study, typically providing the basis for the other trends in evidence. These key trends include an increase in automated processing, use of analysis-ready data (especially those with atmospheric correction), and use of cloud computing platforms, all over increasing large areas. The nature of change methods has evolved from representative bi-temporal pairs to time series of images capturing dynamics and trends, capable of revealing both gradual and abrupt changes. The result also revealed a greater use of nonparametric classifiers for Landsat change detection analysis. Landsat-9, to be launched in September 2021, in combination with the continued operation of Landsat-8 and integration with Sentinel-2, enhances opportunities for improved monitoring of change over increasingly larger areas with greater intra- and interannual frequency.

scholarly journals Screening for Melanoma and Other Skin Cancer Shows a Higher Early Melanoma Incidence: Social Educational Program “Life Fear-Free”

2021 ◽  
Vol 8 (1) ◽  
pp. 54-68
Author(s):  
Lev Demidov ◽  
Igor Samoylenko ◽  
Nina Vand ◽  
Igor Utyashev ◽  
Irina Shubina ◽  
...  
Keyword(s):  
Skin Cancer ◽  
Screening Program ◽  
Excisional Biopsy ◽  
Skin Lesions ◽  
Detection Methods ◽  
Non Melanoma Skin Cancer ◽  
The Social ◽  
Educational Campaign ◽  
Skin Cancer Detection ◽  
The Impact

Background: The screening program Life Fear-Free (LFF) aimed at early diagnosis of cutaneous melanoma (CM) was introduced in Samara, Chelyabinsk, Yekaterinburg, and Krasnodar (Russia) in 2019. Objectives: To analyze the impact of the program on early CM and non-melanoma skin cancer (NMSC) detection. Methods: According to the social educational campaign, people were informed about CM risk factors and symptoms and were invited for skin examination. The program planned to involve 3200 participants in total. Participants with suspicious lesions were invited for excisional biopsy. Results: 3143 participants, including 75.4% women, were examined for skin lesions. The average age of the participants was 43.7 years. Mostly skin phototypes II and III were registered (48.2% and 41.0%, respectively); 3 patients had CM, 15 had basal cell carcinoma, and 1 had Bowen’s disease, which were confirmed histologically. All detected melanomas had Breslow’s thickness of 1 mm. Conclusion: The participants showed high interest in early skin cancer detection programs. The incidence rate of CM and NMSCs among the program participants was higher than in general public. The early disease grade was proven for the detected CMs and NMSCs. The study has shown that it is important to continue such programs.

scholarly journals Influence of CFRC Insulating Plates on Spark Plasma Sintering Process

Metals ◽  
2021 ◽  
Vol 11 (3) ◽  
pp. 393
Author(s):  
Alexander M. Laptev ◽  
Jürgen Hennicke ◽  
Robert Ihl
Keyword(s):  
Temperature Distribution ◽  
Spark Plasma Sintering ◽  
Energy Demand ◽  
Composite Powders ◽  
Fem Method ◽  
Plasma Sintering ◽  
Axial Temperature ◽  
Spark Plasma ◽  
Power And Energy ◽  
The Impact

Spark Plasma Sintering (SPS) is a technology used for fast consolidation of metallic, ceramic, and composite powders. The upscaling of this technology requires a reduction in energy consumption and homogenization of temperature in compacts. The application of Carbon Fiber-Reinforced Carbon (CFRC) insulating plates between the sintering setup and the electrodes is frequently considered as a measure to attain these goals. However, the efficiency of such a practice remains largely unexplored so far. In the present paper, the impact of CFRC plates on required power, total sintering energy, and temperature distribution was investigated by experiments and by Finite Element Modeling (FEM). The study was performed at a temperature of 1000 °C with a graphite dummy mimicking an SPS setup. A rather moderate influence of CFRC plates on power and energy demand was found. Furthermore, the cooling stage becomes considerably longer. However, the application of CFRC plates leads to a significant reduction in the axial temperature gradient. The comparative analysis of experimental and modeling results showed the good capability of the FEM method for prediction of temperature distribution and required electric current. However, a discrepancy between measured and calculated voltage and power was found. This issue must be further investigated, considering the influence of AC harmonics in the DC field.

A noise reduction method for semi-supervised community detection based on harmonic function

2018 ◽  
Vol 32 (14) ◽  
pp. 1850166 ◽  
Author(s):  
Lilin Fan ◽  
Kaiyuan Song ◽  
Dong Liu
Keyword(s):  
Harmonic Function ◽  
Prior Knowledge ◽  
Community Detection ◽  
Detection Methods ◽  
Detection Process ◽  
Knowledge Based ◽  
Detection Approach ◽  
Series Of Experiments ◽  
Novel Strategy ◽  
The Impact

Semi-supervised community detection is an important research topic in the field of complex network, which incorporates prior knowledge and topology to guide the community detection process. However, most of the previous work ignores the impact of the noise from prior knowledge during the community detection process. This paper proposes a novel strategy to identify and remove the noise from prior knowledge based on harmonic function, so as to make use of prior knowledge more efficiently. Finally, this strategy is applied to three state-of-the-art semi-supervised community detection methods. A series of experiments on both real and artificial networks demonstrate that the accuracy of semi-supervised community detection approach can be further improved.

Effect of Inlet Configuration on Moderator Velocity and Temperature Distribution Inside the Calandria of a Heavy Water Reactor

2008 ◽  
Author(s):  
Abhijeet Mohan Vaidya ◽  
Naresh Kumar Maheshwari ◽  
Pallippattu Krishnan Vijayan ◽  
Dilip Saha ◽  
Ratan Kumar Sinha
Keyword(s):  
Temperature Distribution ◽  
Impact Velocity ◽  
Heavy Water ◽  
Computational Study ◽  
Water Reactor ◽  
Heavy Water Reactor ◽  
The Impact

Computational study of the moderator flow in calandria vessel of a heavy water reactor is carried out for three different inlet nozzle configurations. For the computations, PHOENICS CFD code is used. The flow and temperature distribution for all the configurations are determined. The impact of moderator inlet jets on adjacent calandria tubes is studied. Based on these studies, it is found that the inlet nozzles can be designed in such a way that it can keep the impact velocity on calandria tubes within limit while keeping maximum moderator temperature well below its boiling limit.

Influence of Geometry Parameters on Durability of Concrete Structures Exposed to Chloride Environment

2012 ◽  
Vol 204-208 ◽  
pp. 3194-3200
Author(s):  
Xin Gang Zhou ◽  
Hui Xia
Keyword(s):  
Concrete Structures ◽  
Chloride Content ◽  
Chloride Diffusion ◽  
Rectangular Section ◽  
Circular Section ◽  
Concrete Members ◽  
Numerical Stimulation ◽  
Numerical Computing ◽  
Chloride Environment ◽  
Cover Thickness

Finite difference method (FDM) is used to numerical stimulation analysis for chloride diffusion in concrete. By numerical computing, comparison of chloride content profile in different concrete members with different sectional shapes is made. Calculation and comparison show the chloride content prolife in rectangular and circular section has obvious difference. If the side length of rectangular section is equal to the diameter of circular section, as well as the material property and environment, the chloride content in rectangular section is higher than that in that in circular section. In the calculation example, the chloride content at the depth of reinforcement of circular section is about 50-60% that of rectangular section. This tendency is more remarkable in less section dimension, as well as less cover thickness. With the increasing of section, the ratio of difference becomes to be less until to a constant value. In durability design and service life prediction of concrete structures, the section shape and dimension influence should be taken to consideration.

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