Non-intrusive Inspection Research Articles

Development of HOIS guidance for ultrasonic NDT for non-intrusive inspection at elevated temperatures

The non-intrusive inspection (NII) of pressure vessels using external in-service ultrasonic NDT has multiple advantages compared to internal visual inspection, including the significant reduction of down-time related costs and safety benefits from avoiding manentry into vessels. The HOIS joint industry project, with support from the Net Zero Technology Centre (NZTC), has recently been focussing on NII of components with operating temperatures of up to 250°C (typical of upstream applications). These inspections are challenging because they require probes to be in contact with the hot surface much longer than for spot thickness measurements. The aim of the work has been to develop recommendations for in-service inspection of components at relatively high operating temperatures, thereby extending the benefits of the NII process, including avoiding or deferring internal visual inspection, to a wider range of vessels. Experimental trials have been performed on test components at up to ~250°C, with an emphasis on scanning ultrasonic systems used for corrosion mapping and weld inspection using TOFD and angled-beam phased-array (PA). The most successful trials gave corrosion mapping and TOFD weld examination results that had similar differences from benchmark values to those achieved in earlier ambient temperature trials. For angled-beam PA, it was found that some trials appeared to have issues with accurate correction of the data for the effects of the elevated component temperature on both the refracted beam angle and signal arrival times. Other trials were more successful in this respect. The lessons learned from trials on both ex-service and manufactured samples are leading to the development of specific guidance for NII at elevated temperatures. The paper highlights the technical challenges associated with ultrasonic scanning systems at elevated temperatures, share the lessons learned from the experimental trials and summarise the guidance developed.

Quantitative Visualization of Buried Defects in GFRP via Microwave Reflectometry.

Glass fiber-reinforced polymer (GFRP) is widely used in engineering fields involving aerospace, energy, transportation, etc. If internal buried defects occur due to hostile environments during fabrication and practical service, the structural integrity and safety of GFRP structures would be severely undermined. Therefore, it is indispensable to carry out effective quantitative nondestructive testing (NDT) of internal defects buried within GFRP structures. Along with the development of composite materials, microwave NDT is promising in non-intrusive inspection of defects in GFRPs. In this paper, quantitative screening of the subsurface impact damage and air void in a unidirectional GFRP via microwave reflectometry was intensively investigated. The influence of the microwave polarization direction with respect to the GFRP fiber direction on the reflection coefficient was investigated by using the equivalent relative permittivity calculated with theoretical analysis. Following this, a microwave NDT system was built up for further investigation regarding the imaging and quantitative evaluation of buried defects in GFRPs. A direct-wave suppression method based on singular-value decomposition was proposed to obtain high-quality defect images. The defect in-plane area was subsequently assessed via a proposed defect-edge identification method. The simulation and experimental results revealed that (1) the testing sensitivity to buried defects was the highest when the electric-field polarization direction is parallel to the GFRP fiber direction; and (2) the averaged evaluation accuracy regarding the in-plane area of the buried defect reached approximately 90% by applying the microwave reflectometry together with the proposed processing methods.

A semiempirical transparency model for dual energy cargo radiography applications

Cargo containers passing through ports are scanned by non-intrusive inspection systems to search for concealed illicit materials. By using two photon beams with different energy spectra, dual energy inspection systems are sensitive to both the area density and the atomic number of cargo contents. Most literature on the subject assumes a simple exponential attenuation model for photon intensity in which only free streaming photons are detected. However, this approximation neglects second order effects such as scattering, leading to a biased model and thus incorrect material predictions. This work studies the accuracy of the free streaming model by comparing it to simulation outputs, finding that the model shows poor atomic number reconstruction accuracy at high-Z and suffers significantly if the source energy spectra and detector response function are not known exactly. To address these challenges, this work introduces a semiempirical transparency model which modifies the free streaming model by rescaling different components of the mass attenuation coefficient, allowing the model to capture secondary effects ignored by the free streaming model. The semiempirical model displays improvement agreement with simulated results at high-Z and shows excellent extrapolation to materials and thicknesses which were not included during the calibration step. Furthermore, this work demonstrates that the semiempirical model yields accurate atomic number predictions even when the source spectra and detector response are not known exactly. Using the semiempirical model, manufacturers can perform a simple calibration to enable more precise Z reconstruction capabilities, which has the potential to significantly improve the performance of existing dual energy radiographic systems.

The Interactive Effects of Parental Mediation Strategies in Preventing Cyberbullying on Social Media.

Applying the parental mediation theory, this study investigates the main effects and interactive effects of three parental social media strategies, ie, active mediation, restrictive mediation, and non-intrusive inspection, on cyberbullying among teenagers. A matched child-parent survey was conducted with 642 secondary-school students aged 13-18 and their parents in China. The results showed that active mediation was negatively associated with both cyberbullying victimization and perpetration. Restrictive mediation was not significantly associated with cyberbullying. Non-intrusive inspection was positively associated with cyberbullying perpetration but not associated with cyberbullying victimization. Moreover, the two-way interaction between active and restrictive mediation as well as the three-way interaction between the three parental mediation strategies significantly affected cyberbullying perpetration and victimization. Specifically, the combination of high-level active mediation and non-intrusive inspection with low-level restrictive mediation was the most effective strategy for preventing cyberbullying. This finding significantly contributes to the parental mediation literature and provide theoretical guidelines for parental intervention to prevent cyberbullying among teenager.

Potential increased radiological risk in cargo scanning activity

The image-based cargo inspection systems are generally intended to identify illegal practices. However, imaging processes from the scanning of motorized containers have been used for increasing industrial safety. This is made possible by the application of high-energy particle linear accelerators (linac). Measurements of both the environmental equivalent dose rate (δH*(10), and the integrated environmental equivalent dose (H*(10) were performed. The estimation of δH*(10) and H*(10) in the scanning channel, including the driver’s cab of the truck transporting the container, is critical. The aim of this study is to check the radiological safety for occasional users (drivers) by comparing the levels of δH*(10) and H*(10) with those adopted for public exposure. The study was experimentally conducted in a cargo and container inspection facility that uses a linac operating at the maximum energy of 4.5 MeV. During the in situ measurements, a SpiR-ID identifier detector Model F 8929 MGP manufactured by Mirion Technologies was used. The measurements in the driver’s cab suggest that the procedure can be considered safe. However, a fast transient of δH*(10) was identified recording raised values (peaks) around 210× the threshold for public exposures in the first 9 s of each scanning procedure.

Non-intrusive inspection of cargo containers using the C-BORD Rapidly Relocatable Tagged Neutron Inspection System

The European H2020 project, entitled “effective Container inspection at BORDer control points” (C-BORD), aims to develop a framework of Non-Intrusive Inspection (NII) technologies, for containers and large-volume freight at the EU borders. In this article the first results of the field trials of the Rapidly Relocatable Tagged Neutron Inspection System (RRTNIS) are reported. The tests were carried out at the customs administration of the Netherlands' (DCA) facility in the seaport of Rotterdam, the Netherlands. For the tests mock-up cargo containers were prepared. The containers were analyzed using the whole set of NII subsystems of the C-BORD framework. Each container underwent a session of subsequent scans with all the subsystems, in order to realistically reproduce the normal flow of inspections at the customs facility. The RRTNIS was tested under these realistic conditions, as well. The system was able to separate and identify the target materials, in mock-up containers, and improve the state-of-the-art in terms of the detected quantities.

Application and Advances in Radiographic and Novel Technologies Used for Non-Intrusive Object Inspection.

Increase in trading and travelling flows has resulted in the need for non-intrusive object inspection and identification methods. Traditional techniques proved to be effective for decades; however, with the latest advances in technology, the intruder can implement more sophisticated methods to bypass inspection points control techniques. The present study provides an overview of the existing and developing techniques for non-intrusive inspection control, current research trends, and future challenges in the field. Both traditional and developing methods, techniques, and technologies were analyzed with the use of traditional and novel sensor types. Finally, it was concluded that the improvement of non-intrusive inspection experience could be gained with the additional use of novel types of sensors (such as biosensors) combined with traditional techniques (X-ray inspection).

Evaluation of the radiological risk in cargo scanning by comparison with known biological consequences

This study proposes a quick, easy, and low-cost method that can be used to assess the radiological safety of an irradiation line used for cargo and container inspection facilities. The radiation-emitting equipment used was a Smiths Heimam particle accelerator model HCVP4029 operating at 4.5 MeV. The radiation dose measurements were performed using a personal radiation monitor Ultra Radac mod MRAD 111 (Geiger–Muller). The ambient equivalent dose H*(10) was estimated for two facilities: A (real) (1.12E-03 mSv per scan) and B (fictitious) (3.25E-03 mSv per scan). The dimensionless factor R, which represents a ratio between two specific scanning (Ss) quantities regarding the facilities A and B, is introduced as a reference for assessing the level of radiological safety. This study compares facilities A and B by using a simple alternative safety assessment based on the R factor. The dimensionless R-value appears to be able to facilitate both the personnel’s and the general public’s perception of risk levels, even with no fixed scale.

MCNPX computational modeling applied to the potential dose rates calculation of cargo scanning

This study focusses on the risk of potential exposure to radiation for personnel driving a truck as well as illegal individuals being transported in cargo containers. Inspection facilities usually use a high energy linear accelerator (linac) in order to inspect the cargo. Since this type of equipment has associated health risks due to potential unwanted exposure, the occupational and public dose limits should be calculated in order to develop safer work conditions. This work used a computation model running the code MCNPX to simulate a typical cargo inspection facility which used a linac operating at 4.5 MeV. Two scenarios were considered: (1) exposure of the driver to the primary beam due to a potential failure of the safety sensors; and (2) dose received by an illegal individual being transported inside the cargo container. The results show a dose of 0.8514 mSv per scan for the driver exposed to the primary X-ray beam, and 0.1997 mSv per scan for an individual transported in the cargo box. In conclusion, both the individual and the driver received a dose below the acceptable limit considered safe for an individual (1 mSv/year). However, that was the value of one scan; in a case in which multiple scans would be performed, the dose limit can be quickly exceeded. In that case, the limit would be exceeded by the driver faster than by the individual in the cargo.

Performances of C-BORD’s Tagged Neutron Inspection System for Explosives and Illicit Drugs Detection in Cargo Containers

In the frame of the effective Container inspection at BORDer control points (C-BORD) project [H2020 program of the European Union (EU)], a Rapidly Relocatable Tagged Neutron Inspection System (RRTNIS) has been developed for a nonintrusive inspection of cargo containers, aiming at explosives and other illicit goods detection. Twenty large-volume NaI detectors are used to determine the elements composing inspected materials from their specific gamma-ray spectra signatures induced by fast neutrons. The RRTNIS inspection is focused on a specific suspect area selected by X-ray radiography. An unfolding algorithm decomposes the energy spectrum of this suspect area on a database of pure element gamma signatures. A classification is then performed between inorganic materials, such as metals, ceramics, or chemicals, and organic materials like wood, fabrics, or plastic goods. Concerning organic materials, the obtained elemental proportions of carbon, nitrogen, and oxygen allow discriminating explosives from illicit drugs and benign substances. This article reports on the final laboratory tests performed at Commissariat L'Energie Atomique et aux Energies Alternatives (CEA) Saclay, France, to assess the RRTNIS detection performances before further demonstration tests in a real seaport environment. Simulants of explosives and illicit drugs have been hidden at different depths inside iron or wood cargo materials, which are representative of the different neutron and gamma attenuation properties encountered in real cargo containers. Hundreds of experiments have been performed, showing that a few kilograms of explosives or narcotics can be detected by the RRTNIS in 10-min inspections.

Nonintrusive Inspection of Moisture Damp in Composited Insulation Structure Based on Terahertz Technology

Moisture damp has been identified as one of the most harmful agents of multilayer composited insulation, which can seriously accelerate its degradation, cause unexpected failure, and even lead to catastrophic accidents. This article proposes a nonintrusive method for moisture inspection of multilayer insulation structure based on terahertz (THz) technology with a focus on the cable terminal of the electric multiple units (EMUs). First, a three-layer scattering model is established based on the actual structure of the composite cable terminal, and theoretical analysis is performed to reveal the potential application mechanism. Based on that, an artificial model of a three-layer structure is then built on which the insulation damp test is carried out. Finally, the THz spectrum and THz imaging tests are performed. Results show that the frequency-domain signal can effectively identify the moisture inside the multilayer composited insulation. The imaging results in the frequency domain of the sample can accurately determine the geometric parameters of the damp area. By further analyzing the time-domain spectroscopy, the thickness of insulation affected by moisture can be identified quantitatively. This article verifies the feasibility of THz technology in inspecting the moisture dampness of multilayer composite insulation and its potential application in the damp condition assessment of EMU cable terminals.

Muography and Its Potential Applications to Mining and Rock Engineering

Muography is a novel imaging method using natural cosmic-ray radiation for characterising and monitoring variation in average material density in a diverse range of objects that cannot be imaged by conventional imaging techniques. Muography includes muon radiography and muon tomography. Cosmic-ray-induced muons were discovered in the 1930’s, but rapid development of both muographic techniques has only occurred in the last two decades. With this rapid development, muography has been applied or tested in many fields such as volcano imaging, archaeology, underground structure and tunnel detection, rock mass density measurements, cargo scanning, imaging of nuclear waste and reactors, and monitoring of historical buildings and the inside of blast furnaces. Although applications of muography have already touched mining and rock engineering, such applications are still rare and they are just beginning to enter the market. Based on this background, this paper aims to introduce muography into the fields of mining and rock engineering. First, the basic properties of muons are summarized briefly. Second, potential applications of muography to mining and rock engineering are described. These applications include (1) monitoring temporal changes in the average material density of fracturing and deforming rock mass; (2) detecting geological structures and isolated ore bodies or weak zones in mines; (3) detecting a reservoir or boulders during tunnelling or drifting; (4) monitoring caving bodies to search remaining ore; (5) evaluating and classifying rock masses; (6) exploring new mineral deposits in operating underground mines and their surrounding brownfields. Finally, some issues such as maximum depth muons can reach are discussed.

First evaluation of fast neutron imaging with LiInSe2 semiconductors

Fast neutron imaging is a powerful tool to investigate elemental/isotopic compositions of objects, supporting both scientific studies as well as cargo scanning. Current neutron imaging systems are faced with challenges associated with timing, detection efficiency, and/or spatial resolution. Here, we report on the use of a semiconducting lithium indium diselenide neutron sensor coupled to a Timepix ASIC for fast neutron imaging. Using a 15 cm thick copper knife edge, the spatial resolution of the neutron imager was found to be 1.55 mm for 9 MeV neutrons. The experimental detection efficiency at 9 MeV was in general agreement with calculations.

Development and validation of a parental social media mediation scale across child and parent samples

Purpose Social media use carries both opportunities and risks for children and adolescents. In order to reduce the negative impacts of social media on youth, the authors focus our efforts on parental mediation of social media. Specifically, the purpose of this paper is to enhance the conceptualization and operationalization of parental mediation of social media. Design/methodology/approach First, the authors conducted focus groups with both children and parents in Singapore to categorize parental mediation strategies for social media and develop an initial scale of these strategies. Then, a survey was conducted with a nationally representative sample of 1,424 child participants and 1,206 parent participants in Singapore to develop and test the scale. Findings The focus group results identified four conceptually distinct parental mediation strategies for social media, labeled as active mediation, restrictive mediation, authoritarian surveillance, and non-intrusive inspection, and were used to develop an initial scale of these strategies. Based on the data from survey questionnaires, the authors investigated both inter-item and item-total correlations and performed confirmatory factor analysis (CFA), which developed and validated the scale of parental mediation of social media. Originality/value First, this research explained what parents do to manage children’s social media use and identified four conceptually distinct parental mediation strategies of social media, making a significant contribution to the parental mediation theory. Additionally, the research developed the first theory-derived, successively validated and reliable scale in parental mediation of social media.

An Automated method for the analysis of bearing vibration based on spectrogram pattern matching

As a mean for non-intrusive inspection of bearing systems, the scope of predicting their condition from the acoustic vibrations liberated during their operation, utilizing signal processing methods, has been of extensive research, over decades. Vibration being highly non-stationary, time domain as well as spectral features cannot characterize its behavior. Even though spectrogram is a time-frequency domain feature extraction technique, its interpretation is tedious and perhaps, subjective. In the proposed method, the spectrogram images of the normal vibration data is compared with that of the contextual vibration, using Structural Similarity Index Metric (SSIM). It is hypothesized that the pattern similarity between the contextual spectrogram and the baseline is low when the bearing is faulty. The SSIM between the spectrogram image of normal bearing vibration data and the baseline is different from those between the baseline and vibration data corresponding to Inner Race Failure (IRF), Roller Element Defect (RED) and Outer Race Failure (ORF). Via the proposed method of spectrogram pattern matching based on SSIM, the subjectivity in the comparative interpretation of spectrogram is eliminated fully. The SSIM corresponding to the vibrations acquired from the normal and faulty bearings differ with a P value of 4.43693x 10-16. The technique can distinguish defective bearings with, 95.74% sensitivity, 96% accuracy and 100% specificity, without dismantling or open intervention

X-ray Cargo Scanning and Risk Management in Trade Facilitation: Analysis & Model of an Online Imaging and Documentation Management System

X-ray Cargo Scanning and Risk Management in Trade Facilitation: Analysis & Model of an Online Imaging and Documentation Management System

Implication on Customs Administration of the Cross-border e-Commerce Framework of Standards of WCO

Cross-border e-Commerce is presenting a number of new challenges and opportunities to governments. The fast-growing trading environment requires comprehensive and well-considered solutions from all stakeholders, including customs authorities, to manage the unprecedented growth in volumes, overcome the lack of global standards and guidelines, and address associated border risks. Efficiency of clearance and delivery of low-value and small parcels is most particularly crucial. To manage e-commerce transactions, Customs administration units need to engage with all relevant stakeholders with a view to collectively defining the appropriate approach to adopt both from a trade facilitation and enforcement perspective. WCO has developed a set of global standards, associated guidelines and recommendations to facilitate cross-border e-Commerce and thus published the Cross-border e-Commerce Framework of Standards. In this paper, we analyze the contents of the framework and make reference to customs authorities. The core essence of the framework is the exchange of advance electronic data for effective risk management and enhanced facilitation of growing volumes of small and low-value shipments by adopting simplified procedures with respect to clearance, revenue collection and return. It also encourages the use of non-intrusive inspection (NII) equipment, data analytics and other cutting-edge technologies.

Muon Tracing and Image Reconstruction Algorithms for Cosmic Ray Muon Computed Tomography.

Cosmic ray muon-computed tomography (μCT) is a new imaging modality with unique characteristics that could be particularly important for diverse applications including nuclear nonproliferation, spent nuclear fuel monitoring, cargo scanning, and volcano imaging. The strong scattering dependence of muons on atomic number Z in combination with high penetration range could offer a significant advantage over existing techniques when dense, shielded containers must be imaged. However, μCT reconstruction using conventional filtered back-projection is limited due to the overly simple assumptions that do not take into account the curved path caused by multiple Coulomb scattering prompting the need for more sophisticated approaches to be developed. In this paper, we argue that the use of improved muon tracing and scattering angle projection algorithms as well as an algebraic reconstruction technique should produce muon tomographic images with improved quality - or require fewer muons to produce the same image quality - compared to the case where conventional methods are used. We report on the development and assessment of three novel muon tracing methods and two scattering angle projection methods for μCT. Simulated dry storage casks with single and partial missing fuel assemblies were used as numerical examples to assess and compare the proposed methods. The reconstructed images showed an expected improvement in image quality when compared with conventional techniques, even without muon momentum information, which should lead to improved detection capability, even for partial defects.

Non-intrusive detection and characterisation of bearing faults from the temporal features of vibration

ABSTRACT The behaviour of vibrations is widely used for non-intrusive inspection and health monitoring of bearings. However, automated methods, intended for predicting the bearing status, greatly depend on the features extracted from the vibration. Generally, time domain features are computationally simpler than frequency and time–frequency domain features. In this paper, the ability of time domain features to characterise the type of bearing fault is analysed. Types of bearing faults considered are healthy, inner race failure (IRF), roller element defect (RED) and outer race failure (ORF).The features being analysed are standard error (SE), absolute deviation of SE from the reciprocal of number of samples (β), entropy (E), variance (µ), standard deviation (SD), peak amplitude (PA), RMS, crest factor (CRF), impulse factor (IF), shape factor (SHF), energy and clearance factor (CLF). Among these, SE, ‘β’, IF and SHF characterise the status of bearing and the type of faults better than other features. The SE, ‘β’, IF and SHF corresponding to the vibrations acquired from normal and faulty bearings differ with a ‘P’ value of, 7.13866 × 10−23,7.06651 × 10−23, ≈ 0 and ≈ 0, respectively. These features can be used to distinguish defective bearings with 100% sensitivity and 94.73% specificity.

A distributed data acquisition system for nuclear detectors

Nowadays, many examples of data acquisition (DAQ) software for experimental nuclear physics are monolithic processes that run on a computer attached to the DAQ hardware. In this article we present a distributed DAQ system developed for the C-BORD project. With our system, we propose a novel approach, in which each task related to the different DAQ parts (acquisition, pre-process, analysis, etc.) runs in a separate process. In particular, the system is composed of a set of servers that exchange information through dedicated communication sockets. Therefore, with this architecture, an important advantage is the possibility to run the processes on different computers to distribute the computational load. The initial tests of the system have been giving excellent results, both in terms of performance (i.e., maximum acquisition rates) and stability. The project entitled “Effective container inspection at BORDer control points” (C-BORD) is funded by the European H2020 programme. Its aim is to develop a comprehensive set of technologies for the generalized non-intrusive inspection (NII) of containers and large-volume freight at the European Union border.