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This paper introduces a magnetic displacement sensor comprising of a double-layer parallel cables (PCs) magnetizer, tunnel magnetoresistance (TMR) sensors and magnetic flux concentrating plates (MFCPs). By utilizing a double-layer PCs magnetizer, the background magnetic field in the TMR sensor's location can be eliminated, while enhancing the magnetization field of the workpiece. This ensures that the highly sensitive TMR sensors operates within its measurement range. Additionally, the MFCPs concentrate the magnetic field at the TMR sensor location to further improve the displacement measurement sensitivity. After optimizing the geometry and excitation frequency of the probe with FEM, the probe can achieve displacement measurements with 0.1 mm accuracy in the range of 0.5–6.0 mm for ferromagnetic workpieces with linearity of 4.5 % and average relative error under 2.0 %. [Display omitted] • Parallel cables, magnetic displacement probe, ferromagnetic material, sensitivity enhancement, corrosion detection. • A magnetic displacement probe design replaces permanent magnets with lightweight energized parallel cables (PC). • This probe has minimal background noise and excellent sensitivity. • The probe offers a measuring range spanning 0.5 to 6.0mm, with a precise measuring accuracy of 0.1mm and a relative error of under 2.0%. • This probe holds promise for array displacement sensing and is well-suited for detecting deformation and corrosion in extensive ferromagnetic workpieces. [ABSTRACT FROM AUTHOR]

The assessments of internal thickness reduction of ferromagnetic components are extremely important. Traditional nondestructive testing (NDT) methods are usually non-linear and sometimes the electromagnetic parameters of components are required. In this paper, a thickness reduction testing method based on variable intensity DC magnetization (VIDC-MAG) is proposed. Both theoretical modeling analysis and simulation modeling analysis show that a pole point of magnetic permeability μ m appears with the increase of DC magnetization intensity, which corresponds to an inflection point magnetizing current i m. The i m decreases with the increase of the defect depth of the wall thickness reduction and shows a linear relationship. The experimental results show that the method performs well for the inner wall thickness thinning and the relative error of the measurement results is small. Additionally, the measurement results are related to the width of the thickness reduction, the probe excitation frequency, the magnetic properties of ferromagnetic material and the lift-off distance of the magnetizer. The method is applicable to the thickness variation of the cover layer and does not need to know the electromagnetic parameters of the components in advance, which has greater practical application value. [ABSTRACT FROM AUTHOR]

Longitudinal and transverse cracks that appear in the manufacturing and processing of square steel billets are a critical safety hazard. An integrated alternating current magnetic flux leakage (ACMFL) detection probe is composed of parallel cables (PC) magnetizer and pick-up coils manufactured by flexible printed circuit (FPC). Experiments verified the probe could detect longitudinal and transverse cracks in a unidirectional scan. It was proven that when the probe scans the cracks parallel to the direction of the magnetic flux line, the signal at the end of the crack mainly originates from the local magnetic flux leakage (LMFL) field. With an increase in the frequency, the LMFL characteristics become more obvious. Experiments show that the probe can effectively detect longitudinal cracks with a width of 0.4 mm or more when the depth is 0.4 mm, and cracks with a depth of more than 0.3 mm when the width is 1.0 mm in the axial scanning. [Display omitted] • The content discussed in the paper is inspiring for the AC-MFL probe design. • The probe offers a new solution for the inspection of both the transverse and longitudinal defects of square steel billet. • The mechanisms of the AC-MFL method and the ACFM method for detecting cracks in different directions have been analyzed. [ABSTRACT FROM AUTHOR]

DC magnetization is generally considered to suppress the usual local magnetic permeability variation of ferromagnetic materials but also causes neglected non-uniform magnetic characteristics. This paper proposes a new magnetic permeability perturbation testing (MPPT) method, which uses DC magnetization to excite surface permeability perturbation of deeply buried defects and uses an eddy current probe to sense this surface permeability perturbation. The mechanism of MPPT is analyzed in detail and verified by a series of experiments. The effects of the differential distance of probe, crack size, insulation thickness, and excitation frequency on MPPT are investigated experimentally. Finally, the comparison of the proposed MPPT method with traditional eddy current testing and magnetic flux leakage testing is discussed in detail. The proof-of-concept results indicated that the MPPT testing method can realize the detection of internal defects of a 25 mm thick steel plate. This method is completely feasible and has great practical value as a supplement to conventional nondestructive testing methods. [ABSTRACT FROM AUTHOR]

• Five different and new magnetic imaging methods for wire rope were proposed and compared. • Three different magnetic image processing and feature extraction algorithms were presented. • Quantitative wire rope defect inspection and nondestructive evaluation models were proposed and built. • The feasibility and validity of the proposed methods were verified through the wire rope defect inspection under strong noises. As a reliable and flexible loading tool, wire rope has been widely applied in various of industries and practical applications. Nondestructive testing and evaluation for wire rope defect inspection have become necessary methods in safety guaranteeing. However, traditional one-dimensional (1D) and two-dimensional (2D) magnetic flux leakage (MFL) signal processing methods for wire rope nondestructive evaluation (NDE) may lead to miss and false detection, especially under complex operation conditions with strong noise interference. Thus, a new MFL imaging and quantitative defect recognition method is proposed. Based on the reshaped sine function, wavelet transformation and grid entropy matrix reconstruction, five different MFL imaging algorithms are presented and compared. Besides, three MFL image processing methods through the Gabor filtering, morphological filtering, and small object feature extraction as well as the quantitative centroid distance calculation are also investigated. Finally, the quantitative evaluation model for wire rope defect inspection is built and tested in the case study and performance comparison, where six groups of wire rope testing signal recognition results not only verify the feasibility and validity of the proposed quantitative methods, but also demonstrate its great application promise in wire rope defect evaluation under sophisticated conditions. Additionally, advantages and disadvantages of the proposed method as well as the future wok are discussed. [ABSTRACT FROM AUTHOR]

• The significant attenuation of the leakage magnetic field in the lift-off layer is considered. • The ferromagnetic lift-off layer with through groove can enhance the leakage magnetic field of the crack. • The principle relies on the mutual magnetization enhancement effect between the crack and the through groove. [Display omitted] In conventional magnetic flux leakage (MFL) detection, a lift-off layer based on air or non-ferromagnetic wear-resistant material is employed to prevent magnetic sensors from wearing. However, the increase of the lift-off will lower the detection sensitivity and reduce the MFL signal amplitude. To address the issue, theoretical analysis was used to investigate the effect of the ferromagnetic lift-off layer on MFL detection in this study. Then, we put forward a new MFL detection method based on the ferromagnetic lift-off layer. A through groove is machined in the ferromagnetic lift-off layer, which creates an air gap below the sensor. The leakage magnetic field (LMF) generated by the through groove increases the local magnetization intensity around the crack on the sample, while the LMF generated by the crack increases the magnetization intensity surrounding the through groove of the lift-off layer. As a result, the magnetic sensor above the through groove detects a greater MFL signal. In addition, the effect of applied magnetization intensity, groove width, and lift-off layer thickness on the detection signal were explored by experiments. The practicality of the proposed method of detecting different size cracks of nearside and farside were studied. In summary, experiments show that the ferromagnetic steel sheet with a through groove strengthens the MFL signal of the nearside and farside cracks. [ABSTRACT FROM AUTHOR]

• Experiment for wire rope inspection by hall sensor and MFL testing is conducted. • Influence of the signal processing parameters to defect identification is studied. • Interference signals could be eliminated when the parameters were suitably set. • Comparisons of different signal processing methods are conducted and analyzed. • A reference for selection of wire rope defect signal processing method is formed. Steel wire rope (SWR) defect signal processing techniques and methods are the key to exact defect detection and identification, which is important in guaranteeing human lives and property. But the inspection signals sensed by the commonly used inductive coil sensor are often susceptible to the detector's scanning speed, wire rope shaking and vibration, whereas they are unaffected when induced by hall element sensor. Thus, the experiments for wire rope local fault (LF) of broken wire inspection by hall sensors and magnetic flux leakage (MFL) testing method are conducted, and different groups of original signals are obtained. Then, performances of multiple signal processing methods are compared and evaluated in the perspective of baseline drift elimination and signal denoising. Besides, the main impact parameters in these signal processing methods are investigated and revealed. Finally, comparisons and discussions for different filtering methods are analyzed and presented. [ABSTRACT FROM AUTHOR]

Based on the authors' previous work of magnetic flux leakage (MFL) quantitative description and the research plan especially for the magnetic component of eddy current effect factor B other , further explorations for electromagnetic actions, magnetic and signal presentations in the defect in electromagnetic nondestructive testing (ENDT, such as direct current field measurement (DCFM), MFL and eddy current testing (ECT)) are continued here. Primarily, new discoveries indicate that the magnetic component of B other is actually composed of the secondary magnetic field component of Δ B mfl which manifests as raised signal waves and volume current perturbation component of Δ B Δ I which features as double peaked signals due to the departure or bypassing of the "volume current" in the defect. What's more, the concrete expressions of magnetic components are deduced and given through Ampere's (or the Ampere–Maxwell) law. Afterwards, the theory is well demonstrated and verified by means of finite element analysis for current density and magnetic flux density or MFL signals in typical quasi-static testing by DC magnetization for different specimens with defects. Additionally, suggestions for installation site of sensor elements in ENDT are also given. Finally, a unified evaluation standard for magnetic flux density is formed, which provides the basic theory or analysis principles for the ENDT techniques as well as research directions for precision defect detection and related applications. [ABSTRACT FROM AUTHOR]

Wire rope is a necessary tool in practical applications especially in crane, elevator and bridge construction, which plays an important role in the national economy and daily life, and safety inspection for wire rope is the key to ensure people's life and property. However, detection signals are usually complicated due to the twining structures, which make the wire rope defect signal and strand signal mix together. What's more, no reports and studies have appeared to solve this problem. In view of the situation and challenges above, this paper proposes a combined signal processing method based on notch filtering and wavelet denoising to process detected wire rope signals. Basic time domain, frequency domain and joint time–frequency analysis are first conducted, thereafter, conventional signal processing methods such as lowpass filtering and adaptive analysis are presented according to the signal characterizations. These comparisons and results demonstrate that a conventional single method is incapable of wire-rope-detection signal identification and differentiation. Nonetheless, after the notch filter design and calculation, the processing results for the typical wire rope inspection signals in the experiments indicate that the combined methods can not only distinguish steel wire rope defect signal and strand signal effectively but also with high detection accuracy, even for the inner defect. Finally, the feasibility and reliability are verified by a series of signal processing results and comparisons, which demonstrate that this new method has great application potential and is of vital significance to the development of wire rope safety inspection. [ABSTRACT FROM AUTHOR]

During electromagnetic ultrasonic testing, it is difficult to recognize small-size bottom cracks by time of flight (ToF), and the lift-off fluctuation of the probe affects the accuracy and consistency of the inspection results. In order to overcome the difficulty, a novel composite sensor of an electromagnetic acoustic transducer (EMAT) and pulse eddy current (PEC) is designed. We use the amplitude of a bottom echo recorded by EMAT to identify the tiny bottom crack as well as the amplitude of PEC signals picked up by the integrated symmetric coils to measure the average lift-off of the probe in real time. Firstly, the effects of lift-off and bottom cracks on the amplitude of bottom echo are distinguished by combining the theoretical analysis and finite element method (FEM). And then an amplitude correction method based on the fusion of EMAT and PEC signals is proposed to reduce the impact of lift-off on the defect signal. The experimental results demonstrate that the designed composite sensor can effectively detect a bottom crack as small as 0.1 mm × 0.3 mm. The signal fusion method can accurately correct the amplitude of defect signals and the relative error is less than ±8%.

The quantitative evaluation of defects is extremely important, as it can avoid harm caused by underevaluation or losses caused by overestimation, especially for internal defects. The magnetic permeability perturbation testing (MPPT) method performs well for thick-walled steel pipes, but the burial depth of the defect is difficult to access directly from a single time-domain signal, which is not conducive to the evaluation of defects. In this paper, the phenomenon of layering of magnetization that occurs in ferromagnetic materials under an unsaturated magnetizing field is described. Different magnetization depths are achieved by applying step magnetization. The relationship curves between the magnetization characteristic currents and the magnetization depths are established by finite element simulations. The spatial properties of each layering can be detected by different magnetization layering. The upper and back boundaries of the defect are then localized by a double-sided scan to finally arrive at the depth size of the defect. Defects with depth size of 2 mm are evaluated experimentally. The maximum relative error is 5%.

Conventional water immersion ultrasonic testing faces limitations due to factors such as environmental conditions, workpiece dimensions, corrosion, and resource wastage. Contact-based coupling methods, which employ coupling media or specific coupling structures, offer a convenient approach to coupling acoustic waves and reduce signal attenuation. However, these methods are time-sensitive and lack adaptability to uneven surfaces, particularly when dealing with workpieces featuring subtle undulations, resulting in significant signal decay. This paper presents an ultrasonic coupling method based on a flexible capillary water column array. By employing a stable and flexible water column array within the micro-channels as the coupling medium, stable contact-based transmission of ultrasonic signals is achieved. The influence of water column array unit dimensions and array structures is explored through theoretical analysis and experimentation, demonstrating lower energy attenuation compared to reductions in water column area. Notably, the tests revealed the method's adaptability at oblique angles below 20°, which surpasses the performance of submerged detection at similar angles. This research presents an innovative and stable approach for contact-based ultrasonic coupling testing, particularly in scenarios involving dynamic contact scanning between ultrasonic waves and workpieces., Competing Interests: Declaration of competing interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2024 Elsevier B.V. All rights reserved.)

The study under controlled conditions showed that short-term shading resulted in the increase of resveratrol and polydatin contents in Rumex gmelini root, while long-term shading led to the decrease of them. The increase and decrease were more obvious with increasing shading degree and time. The production of resveratrol reached the maximum in August, while that of polydatin was in September. Shading had a negative effect on the resveratrol and polydatin accumulation in R. gmelini root, but severe shading at the late growth period of R. gmelini increased the production of resveratrol and polydatin.