Assessment Of Defects Research Articles

MONITORING THE DEFORMATION PROCESS OF ENGINEERING STRUCTURES USING BIM TECHNOLOGIES

Abstract. This paper reports on the scientific approach to integrating the results of geodetic measurements into an integrated BIM system for geotechnical monitoring of building structures. The method is based on systematic monitoring of deformations with the determination of the influence of external factors, which makes it possible to process a significant amount of information obtained during the monitoring process and promptly process the information about the stress-strain state of the object in real-time.New technology for assessing the technical condition of high-rise buildings is proposed. The core of this technology is an estimation of defects and deformations of structures using BIM during the building construction and operation.Using the mathematical tools of BIM technology in geotechnical monitoring of engineering structures makes it poss ible to create a quantitative information model. The model comprises the results of geodetic measurements, measurements of climate loads, and measurements of geological deformations. As a result, a quantitative assessment of defects and damage during the construction and operation of high-rise buildings becomes possible.BIM allows determining the risks of critical states occurrence of building structures, assessing the probability level of the ir occurrence, and predicting the degree of influence of these risks on the safe operation of the entire structure. Simultaneously, the BIM estimates the stress-strain state of a high-rise building based on the results of deformation monitoring. The considered approach is affordable to any measurements. The use of information technologies in the monitoring of engineering structures during construction and operation will make it possible to collect and accumulate significant statistical data related to the influence of specific external factors on the stress-strain state of the structure. Subsequent processing of this information will make it possible to identify and predict the dependence of defects and deformations of building structures on certain factors and cla rify their weight values.

Lessons Learned from the Construction, Inspection, and Defect Assessment of Reinforced Concrete Foundations for Wind Turbines

Foundations of wind turbines are subject to challenging conditions during their service life as they support ever larger wind turbines under complex loading situations. There have been numerous reports of cracked concrete foundations of wind turbines. Cracking can impair the durability and serviceability of the foundations, thereby leading to very expensive repairs or even to premature failure of the structure. To avoid cracking-related problems and improve the quality of concrete foundations, it is important to gather information and experience from the production stage and its outcome. However, although problems and defects in the construction of wind turbine foundations are widespread, they have very seldom been documented and reported, in particular from a contractor’s perspective. This article analyses and critically reviews data collected during the production, inspection, diagnosis, and repair activities conducted in relation to the construction of foundations for a wind farm project in Sweden. The extent of defects observed on individual foundations is assessed and used to investigate the eventual relation between the observed deviations and different production aspects. Investigation methods to determine the importance of these defects and their consequences and possible remediation measures are also discussed. Finally, recommendations are proposed to improve the quality control of wind turbine foundations.

Postmortem 9.4-T MRI for Fetuses With Congenital Heart Defects Diagnosed in the First Trimester.

ObjectiveTo evaluate the feasibility of 9. 4-T postmortem MRI (pm-MRI) for assessment of major congenital heart defects (CHD) cases terminated in the early stage of gestation.MethodsFetuses with CHD detected by the detailed first-trimester ultrasound scan and terminated before 18 gestational weeks were recruited between January 2018 and June 2020. All fetuses were offered 9.4-T pm-MRI examinations and those terminated over 13+6 weeks were offered conventional autopsies simultaneously. Findings of pm-MRI were compared with those of conventional autopsy and prenatal ultrasound.ResultsA total of 19 fetuses with major CHD were analyzed, including 6 cases of the atrioventricular septal defect, 5 cases of Tetralogy of Fallot, 3 cases of hypoplastic left heart syndrome, 1 case of tricuspid atresia, 1 case of transposition of the great arteries, 1 case of severe tricuspid regurgitation, and 2 cases of complex CHD. Pm-MRI had concordant findings in 73.7% (14/19) cases, discordant findings in 15.8% (3/19) cases, and additional findings in 10.5% (2/19) cases when compared with prenatal ultrasound. Pm-MRI findings were concordant with autopsy in all 8 CHD cases terminated over 13+6 weeks.ConclusionIt is feasible to exhibit the structure of fetal heart terminated in the first trimester clearly on 9.4-T pm-MRI with an optimized scanning protocol. High-field pm-MRI could provide medical imaging information of CHD for those terminated in the early stage of gestation, especially for those limited by conventional autopsy.

Finite element analysis on grey cast iron assets: a case study on penstocks in the wastewater system

Penstocks have been used in the water industry for flow control since the Victorian expansion and consolidation of clean water and wastewater networks. However, the Victorians were the first to use grey cast iron (GCI) castings to manufacture large scale penstocks. Most of these ageing assets are still in operation; however, engineering assessments are necessary to determine a structure’s fitness for service. Even today, penstocks in the sewer system tend to be made from GCI, due to ease of manufacturing, resistance to corrosion and cost. One characteristic property of GCI is the graphite flake structure in the material, contributing to its low toughness, inconsistency in material strength and brittle behaviour, despite exhibiting slight hardening properties. Finite element analysis (FEA) is a numerical method which allows the analysis of complex structures by splitting it into finite parts and solving them with a computer processor. Despite the versatility of FEA, appropriate considerations and assumptions are necessary due to the difficulty to obtain data from inspection and unique material behaviour of GCI. The article shows concerns for an analysis of GCI penstocks using FEA, which extends into the application of fracture mechanics approaches for defect assessments.

Automated immersion ultrasonic testing technology for debonding defects of the brazed joint of DOME in EAST divertor

Aiming at the problem of non-destructive evaluation of debonding defects on joint interface of DOME in EAST divertor, an automatic water immersion ultrasonic C-scan testing technology based on a six-axis robot is proposed in this research. First, the research and development ideas, principles and control logic of the testing system are explained. Second, testing technologies such as probe selection, reference sensitivity and gate setting, and scanning path planning based on robotic arm teaching technology are introduced in detail. Finally, the testing results of the test blocks and products are presented, and the distribution state and formation reasons of the debonding defects on the bonding surface are analyzed. The results show that the automatic water immersion ultrasonic C-scan inspection system based on the six-axis robot has good adaptability to the surface and high testing sensitivity, which can meet the requirements for product quality and technical specifications. In summary, the proposed technology can realize the non-destructive quantitative assessment of the debonding defects of the brazed joint of DOME.

3D Patient-Specific Biomechanical Model of the Tongue for the Management of Tongue Tumors: Conceptualization to Reality.

Increasing use of tobacco by the younger generation has resulted in an increase in oral cavity tumors. Surgical treatment is radical and results in severe functional morbidity. Using computer-aided designing technology, surgical and rehabilitative planning can be better. We present here our concept of a patient-specific biomechanical 3D model of the tongue and its clinical utility in the management of tongue tumors. Using fused deposition modeling, the 3D model of the tongue was printed which easily differentiates the tumor and the uninvolved tongue by printing in two different colors. The 3D tongue model was used by the surgical and rehabilitation teams to frame the treatment and plan the rehabilitation taking into account the patient preferences and needs. The model was used in two patients with operable squamous cell carcinoma (SCC) of the tongue, and the utility of the model in margin planning, surgical defect assessment, and its aid in the reconstruction and rehabilitation was assessed. Two patients with Stage III SCC of the tongue underwent the surgery based on the plan evolved from the 3D model. All the surgical margins assessed by the frozen section analysis were clear. The model helped in addressing the discordance between patient expectations and surgical outcomes. We found that the model aided the reconstructive surgeon in planning the flap harvest based on the pre-operative defect assessment, which, in turn, translated into better rehabilitative outcomes. 3D biomechanical tongue model is a novel concept and aids in improving the overall treatment outcomes. The realistic 3D reconstructed image model helps the oncologist in planning the resection, enables the reconstructive surgery to more precisely predict the defect volume, and lastly the rehabilitative team in developing better rehabilitation strategies.

Assessment of Transcatheter or Surgical Closure of Atrial Septal Defect using Interpretable Deep Keypoint Stadiometry.

Automated echocardiogram interpretation with artificial intelligence (AI) has the potential to facilitate the serial diagnosis of heart defects by primary clinician. However, the fully automated and interpretable analysis pipeline for suggesting a treatment plan is largely underexplored. The present study targets to build an automatic and interpretable assistant for the transthoracic echocardiogram- (TTE-) based assessment of atrial septal defect (ASD) with deep learning (DL). We developed a novel deep keypoint stadiometry (DKS) model, which learns to precisely localize the keypoints, i.e., the endpoints of defects and followed by the absolute distance measurement with the scale. The closure plan and the size of the ASD occluder for transcatheter closure are derived based on the explicit clinical decision rules. A total of 3,474 2D and Doppler TTE from 579 patients were retrospectively collected from two clinical groups. The accuracy of closure classification using DKS (0.9425 ± 0.0052) outperforms the "black-box" model (0.7646 ± 0.0068; p < 0.0001) for within-center evaluation. The results in cross-center cases or using the quadratic weighted kappa as an evaluation metric are consistent. The fine-grained keypoint label provides more explicit supervision for network training. While DKS can be fully automated, clinicians can intervene and edit at different steps of the process as well. Our deep learning keypoint localization can provide an automatic and transparent way for assessing size-sensitive congenital heart defects, which has huge potential value for application in primary medical institutions in China. Also, more size-sensitive treatment planning tasks may be explored in the future.

Influence assessment of artificial defects on the fatigue behavior of additively manufactured stainless steel 316LVM

The laser powder bed fusion of metals (PBF-LB/M) is one of the most promising techniques to realize lightweight optimized parts and structures. Possible design elements are internal cooling channels or topology optimized geometries. However, not only does the process suffer of instabilities causing pores and lack-of-fusion defects but also a low surface quality. A further knowledge about these defects and their influence on the mechanical behavior are needed to use additively manufactured parts in structural relevant applications. In this work, the austenitic stainless steel 316LVM (X2CrNiMo18-15-3) has been processed by PBF-LB/M. In total, four different batches were manufactured with either no intended porosity or specific cubic defects ranging between 0.3 and 1.5 mm edge length. The fatigue behavior was evaluated at stress ratio R = -1 up to 1E7 cycles. The fracture surface was analyzed by scanning electron microscopy and the relationship between artificial defect size and fatigue strength was investigated by Kitagawa-Takahashi (KT) diagram and its modification by El Haddad’s intrinsic crack length. The results show that the KT-diagram underestimates the fatigue strength of the investigated steel indicating a high defect tolerance and possible hardening mechanisms during cyclic loading such as possible nano-twinning. An influence of the entrapped process gas could also play a role. As long as this is unclear, the models can only be used conservatively as the full potential of the PBF-LB/M steel cannot be fully exploited.

Application of advanced NDT methods to assess structural integrity of pressure vessel welded joints

The review of non-destructive testing of pressure vessel for compressed air is given, as well as the assessment and analysis of defects on the integrity of the vessel itself. The focus here is on welded joints, as the most critical areas in pressure vessels, especially if thickness is large, like in the case considered here (50 mm), cylindrical air storage vessels made of HSLA steel. Toward this end conventional NDT methods, such as UT and Radiography are used in the first phase of this research, providing valuable data for structural integrity assessment based on detected unacceptable defects in welded joints. Anyhow, since few unacceptable defects were found by conventional UT, there was a need to use advanced NDT UT methods, such as Phased Array Ultrasonic Testing (PAUT), to evaluate defect position and size more precisely. In this way risk of failure can be assessed more reliable, which is of utmost importance for pressure vessel where probability of failure is low, but the consequence of failure is potentially catastrophic, like in the case considered here.

Assessment of Abrasion-Induced Visual Defects in Twin Screw Wet Granulation Using Wall Friction Measurements

Starting point of the presented study were abrasion effects occurring during a twin screw wet granulation (TSG) process of a new chemical entity (NCE) formulation, resulting in gray spots on the final tablets. Several actions and systematic changes of equipment and process parameter settings of TSG process were conducted which reduced the visual defect rate of the tablets, i.e., gray spots on the surface, below the specification limit. To understand the rationale and mechanism behind these improvements, correlations of defect rates and wall friction measurements using a Schulze ring shear tester were evaluated. To check the suitability of the method, a broad range of wall materials as well as powder formulations at various moisture levels were investigated with regard to their wall friction angle. As differences in wall friction angle could be detected, further experiments were conducted using wall material samples made out of different screw materials for TSG. Evaluation of these screw wall material samples gave first hints, which screw materials should be preferred in regard of friction for TSG process. In the finally presented case study, wall friction measurements were performed using the above mentioned NCE formulation with known abrasion issues at TSG processing. The results confirmed that changes which led to a reduced visual defect rate of tablets correlated with a decreased wall friction angle. The results suggest wall friction measurements as a potent tool for equipment selection and establishment of a suitable process window prior to conducting TSG experiments.Graphical abstract

Characterization of Plasma Process-Induced Low-Density Defect Creation by Lateral Junction Leakage

In the design of ultralow leakage devices such as image sensors, it is necessary to understand the influence of low-density defects during plasma processing-plasma-induced physical damage (PPD)-on device performance. Defects created by plasma exposure act as carrier conduction sites and induce an increase in leakage (e.g., dark) current. This study proposes a PPD evaluation scheme for low-density defect assessments, specifically defects created in the lateral direction due to lateral stochastic straggling (lateral PPD). Two test structures were designed: a single device with a leakage current (Ileak) and a complementary metal-oxide-semiconductor image sensor (CIS) circuit with a dark current (Idark). The energy level and density of defects distributed in the lateral direction were estimated using the Shockley-Read-Hall (SRH) model. The energy level (Et) was derived using the SRH model from the temperature dependence of Ileak and Idark defined as the activation energy Ea. The trap density (Nt) was also determined. A comprehensive comparison of these parameters was conducted. Both Ileak and Idark are dependent on the contact opening diameter after plasma exposure, which implies the presence of defects in the lateral direction via lateral PPD. From the analysis of the temperature dependence of Ileak and Idark, the lateral PPD influenced the mean value of Ea. Moreover, we confirmed that an increase in Idark indicates an increase in the number of trap sites, and more specifically, an increase in defects at shallow levels. The derived trap site density in the CIS circuit was consistent with that of a single device. The proposed evaluation scheme is useful for PPD evaluation in the presence of low-density defects, and is critical for the design of future low-leakage devices.

Doppler ultrasound assessment of minor atrial septal defects in patients with paradoxical embolism

Minor atrial septal defect (ASD) may be one of the pathways of paradoxical embolism in the brain. Few scientific papers have investigated the relationship between ASD (excluding patent foramen ovale) and the occurrence of ischemic stroke. There is no definite opinion as to how functionally important such shunts are and how the shunt changes with age. The review analyzes modern ideas about the probability of paradoxical embolism in small ASDs from the viewpoint of pathophysiology, and also demonstrates the technological capabilities of assessing the functional significance of such shunts based on our own clinical observations.

English

BACKGROUND Visual field defects are caused by different lesions affecting different sites of visual pathway. Most common causes include stroke and intracranial space occupying lesions. Assessment of visual field defect helps in localization of the lesion along with measurement of the defect. The purpose of this study was to record different types of visual field defects in neuro-ophthalmic diseases. METHODS This cross-sectional observational study was conducted between February 2016 and March 2018 at Department of Ophthalmology, SVRRGG Hospital. Visual field testing was done by confrontation method and Humphreys field analyser with best corrected visual acuity. Patient satisfying inclusion and exclusion criteria are included in the study. RESULTS Among the 58 participants, 37 (64 %) were males and 21 (36%) were females. Cerebrovascular accident was seen in 25 cases which was the most common aetiology followed by pituitary adenomas in 14 cases. Complete homonymous hemianopia was observed in 16 cases which was the most common field defect followed by bi-temporal hemianopia in 12 cases, enlargement of blind spot in 11 cases, incomplete homonymous hemianopia in 7 cases, superior and inferior quadrantanopia in 4 cases each, inferior altitudinal field defects in 2 cases, central scotomas in two cases and superior altitudinal field defect in one case. CONCLUSIONS Visual field defects are used to monitor the progression, recurrence of disease and as a guide for treatment. It is mandatory to record the fields in the neuroophthalmic diseases. KEY WORDS Visual Field Defects, Neuro-Ophthalmic Diseases

Brittle fracture estimation at ends of groove welded joints under cyclic loading

To prevent brittle fracture in structural components during earthquakes, their cumulative ductility (plastic deformation capacity) should be determined beforehand and appropriate countermeasures applied accordingly. In this paper, a method for estimating the cumulative ductility of welded joints with defects based on the σW–Nf relationship and Miner's rule is proposed for steel structure components to facilitate brittle fracture estimation. To verify its effectiveness, it was applied to the testing of welded joints with defects and compared to experimental results. The experimental tests were conducted under cyclic loading conditions to reproduce brittle fractures starting from the ends of complete joint penetration groove welded joints. The joint models used in this study were part of beam-to-column connections between beam flanges and diaphragms. Defects were artificially introduced into the welded joints before the experimental tests; brittle fractures occurred at these preinstalled defects in the welded joint specimens. The calculated cumulative ductility was obtained from the fracture toughness and Weibull stress of the joint model measured using finite element analyses. The calculated cumulative ductility values corresponded well with the experimental results, albeit with some explicable errors. The results indicate that the proposed method can estimate the cumulative ductility for structural components with defects under cyclic loading independent of their materials, notch types, and connection details. Thus, the findings could contribute to the assessment of defects in welded joints in steel structures subjected to earthquake loadings.

Myocardial Perfusion Imaging After Severe COVID-19 Infection Demonstrates Regional Ischemia Rather Than Global Blood Flow Reduction.

Background: Acute myocardial damage is common in severe COVID-19. Post-mortem studies have implicated microvascular thrombosis, with cardiovascular magnetic resonance (CMR) demonstrating a high prevalence of myocardial infarction and myocarditis-like scar. The microcirculatory sequelae are incompletely characterized. Perfusion CMR can quantify the stress myocardial blood flow (MBF) and identify its association with infarction and myocarditis.Objectives: To determine the impact of the severe hospitalized COVID-19 on global and regional myocardial perfusion in recovered patients.Methods: A case-control study of previously hospitalized, troponin-positive COVID-19 patients was undertaken. The results were compared with a propensity-matched, pre-COVID chest pain cohort (referred for clinical CMR; angiography subsequently demonstrating unobstructed coronary arteries) and 27 healthy volunteers (HV). The analysis used visual assessment for the regional perfusion defects and AI-based segmentation to derive the global and regional stress and rest MBF.Results: Ninety recovered post-COVID patients {median age 64 [interquartile range (IQR) 54–71] years, 83% male, 44% requiring the intensive care unit (ICU)} underwent adenosine-stress perfusion CMR at a median of 61 (IQR 29–146) days post-discharge. The mean left ventricular ejection fraction (LVEF) was 67 ± 10%; 10 (11%) with impaired LVEF. Fifty patients (56%) had late gadolinium enhancement (LGE); 15 (17%) had infarct-pattern, 31 (34%) had non-ischemic, and 4 (4.4%) had mixed pattern LGE. Thirty-two patients (36%) had adenosine-induced regional perfusion defects, 26 out of 32 with at least one segment without prior infarction. The global stress MBF in post-COVID patients was similar to the age-, sex- and co-morbidities of the matched controls (2.53 ± 0.77 vs. 2.52 ± 0.79 ml/g/min, p = 0.10), though lower than HV (3.00 ± 0.76 ml/g/min, p< 0.01).Conclusions: After severe hospitalized COVID-19 infection, patients who attended clinical ischemia testing had little evidence of significant microvascular disease at 2 months post-discharge. The high prevalence of regional inducible ischemia and/or infarction (nearly 40%) may suggest that occult coronary disease is an important putative mechanism for troponin elevation in this cohort. This should be considered hypothesis-generating for future studies which combine ischemia and anatomical assessment.

APP-guided assessment of acetabular defects in hip revision arthroplasty: a structured approach to a complex situation

IntroductionAcetabular defect recognition and classification remains a challenging field of practice for orthopedic surgeons. Recently, the Acetabular Defect Classification (ADC) has been introduced to provide a reliable, reproducible and intuitive classification system. In order to improve ease of use and efficiency of the ADC, a browser-based application has been created. We hypothesized that the ADC application can improve rating performance of non-specialists (medical students) to achieve good inter- and intra-rater agreement and will compare favorable to the results of specialists (experienced surgeons) without the help of the application.Materials and methodsThe ADC is based on the integrity of the acetabular rim and the supporting structures. It consists of four main types of defects ascending in severity. These defects are further subdivided in A–C, narrowing down defect location. 80 randomized radiographs were graded according to ADC by three non-specialists (medical students) with help of the ADC application and by three specialists (orthopedic surgeons) without help of the application to evaluate the difference in inter-rater agreement between groups. To account for intra-rater agreement, the rating process was repeated after a reasonable wash-out period.ResultsInter-rater and intra-rater agreement within the non-specialist group rated lower when compared to the specialist group while still falling into the good agreement range. The student group presented with k values of 0.61 for inter-rater agreement and 0.68 for intra-rater agreement, while the surgeon group displayed k values of 0.72 for inter-rater agreement and 0.83 for intra-rater agreement.ConclusionThe app-guided assessment of acetabular defects offers a promising innovative approach to simplify complex situations. It makes the challenging field of acetabular revision arthroplasty more approachable especially for less experienced surgeons and offers insight and guidance in the planning stage as well as intra-operative setting.

Assessment of external defects at mechanical engineering enterprises

The methodology for calculating the constituent elements that form external defects in the manufacture of engineering products is considered. A classic quality control tool, a Pareto chart, is proposed to analyze the causes of defects and their cost. When testing the methodology on the example of the production of gearboxes, it was revealed that the number of defects has a different ranking order relative to the assessment of external losses. For the formation of corrective and preventive actions, it is recommended to use two diagrams at the same time. Keywords: external defect, losses, quality control tools, Pareto chart. boss2569@yandex.ru

Mechanical assessment of defects in welded joints: morphological classification and data augmentation

We develop a methodology for classifying defects based on their morphology and induced mechanical response. The proposed approach is fairly general and relies on morphological operators (Angulo and Meyer in 9th international symposium on mathematical morphology and its applications to signal and image processing, pp. 226-237, 2009) and spherical harmonic decomposition as a way to characterize the geometry of the pores, and on the Grassman distance evaluated on FFT-based computations (Willot in C. R., Méc. 343(3):232–245, 2015), for the predicted elastic response. We implement and detail our approach on a set of trapped gas pores observed in X-ray tomography of welded joints, that significantly alter the mechanical reliability of these materials (Lacourt et al. in Int. J. Numer. Methods Eng. 121(11):2581–2599, 2020). The space of morphological and mechanical responses is first partitioned into clusters using the “k-medoids” criterion and associated distance functions. Second, we use multiple-layer perceptron neural networks to associate a defect and corresponding morphological representation to its mechanical response. It is found that the method provides accurate mechanical predictions if the training data contains a sufficient number of defects representing each mechanical class. To do so, we supplement the original set of defects by data augmentation techniques. Artificially-generated pore shapes are obtained using the spherical harmonic decomposition and a singular value decomposition performed on the pores signed distance transform. We discuss possible applications of the present method, and how medoids and their associated mechanical response may be used to provide a natural basis for reduced-order models and hyper-reduction techniques, in which the mechanical effects of defects and structures are decorrelated (Ryckelynck et al. in C. R., Méc. 348(10–11):911–935, 2020).

Analysis of manufacturing internal pressure induced defects of the pipe wall with modeling of stresses

The analysis of the internal defect of the 426 mm diameter pipe of a compressor station process piping was carried out. The pipeline section has been in operation for 37 years. The defect was detected visually during the repair of the section with cutting out a part of the pipe being inspected for the installation of shut-off valves. When preparing the section for the tie-in, a delamination with a visible length of 30 mm was found at the end of the pipe. According to external signs, the defect has a production reason for the formation. The pipe section with the defect must be replaced in accordance with GOST ISO 10893-8&ndash;2017. Extended non-destructive testing and metallographic examination of the defective area were carried out. The dynamics of changes in the requirements of normative and technical documents for the assessment of defects of this type is considered. Finite element modeling of mechanical hoop stresses in the pipe has been carried out to determine the degree of danger of such defects. The actual configuration of the defect, determined by microscopy, and theoretical models, built according to the data of step-by-step thickness measurement, are implemented as models.

Research on defect detection of high-speed rail based on multi-frequency excitation composite electromagnetic method

The rail under high pressure work will grow damage. In the high-speed railway, defects development initially manifests as opening diagonal defects on the surface and buried defects near surface of the rail, and the existing non-destructive testing (NDT) methods find it difficult to achieve comprehensive detection and assessment of rail surface and near surface defects. This paper proposes a multi-frequency excitation composited electromagnetic detection based on different detection characteristic of the system, which can be used to achieve comprehensive assessment of rail surface and near-surface defects. A high-speed rail experimental system is designed to implement experimental analysis which finds that the system can effectively improve the accuracy, anti-interference and stability of surface defect assessment, and realize the quantitative assessment of buried defects. And the multi-frequency composited electromagnetic detection method can also suppress the attenuation of eddy current signal at high speed and improve the signal-to-noise ratio.