Non-destructive Investigation Research Articles

Mapping the elemental distribution in archaeological findings through advanced Neutron Resonance Transmission Imaging

This work highlights recent application of energy-selective neutron imaging at the ISIS Neutron and Muon Source, specifically focusing on the development of Neutron Resonance Transmission Imaging (NRTI) at the INES instrument. NRTI is a nuclear technique based on resonant neutron absorption reaction, which combines the sensitivity to elemental and isotopic composition with detailed morphological information, using the epithermal portion of the neutron flux available on the INES instrument at the ISIS facility. Unlike standard neutron radiography and tomography methods, NRTI preserves detailed time and energy information for each detector pixel, enabling enhanced visualisation of elemental distribution inside an object’s volume, with the potential for quantitative elemental analysis. These features combined with the non-destructiveness of NRTI make the method promising for applications in the field of Cultural Heritage, especially when it is employed in a multi-technique approach to provide complementary information about the composition and the crystalline structure of archaeological artefacts. A study related to Heritage Science is presented to demonstrate the effectiveness of NRTI in non-destructive investigations of inhomogeneous artefacts, specifically focusing on the excavation finds related to the first evidence of ancient brass production in Milan, Italy, during Roman times.

Inline CT-Analysis of the Melting Area during Fused Filament Fabrication

In the 21st century, 3D printing has become a mainstream process for prototyping and low-volume production. Fused Filament Fabrication is the most commonly used process for 3D printing plastics. A plastic filament is melted in a nozzle and a component is built up layer by layer. As with all manufacturing processes, there is an interest in continuously optimizing and improving the FFF process. One approach is based on process simulation, which provides a better understanding of the process. Subsequently, it is always necessary to validate the simulation models with the real process. This validation has only been possible to a limited extent in the case of FFF. In this work, a method is presented that allows a non-destructive investigation of the melt behaviour during the printing process. For this purpose, a 3D printer nozzle with an extruder was integrated into an X-ray computed tomography system. Thus, a computed tomography scan can be performed during the extrusion process. By using highly absorbent tungsten filaments, sufficient contrast can be created between the metal nozzle and the plastic filament to allow analysis of the melt behaviour. This setup makes it possible to distinguish between the solid filament area and the melt area, as well as to determine the contact between the filament and the die wall. In doing so, simulations can be validated and nozzle geometries can be improved.

High-Frequency and High-Current Transmission Techniques for Multiple Earth Electrical Characteristic Measurement Systems Based on Adaptive Impedance Matching through Phase Comparison.

With the increase in groundwater exploration, underground mineral resource exploration, and non-destructive investigation of cultural relics, high-resolution earth electrical characteristic measurement has emerged as a mainstream technique owing to its advantageous non-destructive detection capability. To enhance the transmission power of the high-frequency transmitter in high-resolution multiple earth electrical characteristic measurement systems (MECS), this study proposes a high-frequency, high-current transmission technique based on adaptive impedance matching and implemented through the integration of resonant capacitors, a controllable reactor, high-frequency transformers, and corresponding control circuits. A high-current precisely controllable reactor with a 94% inductance variation range was designed and combined with resonant capacitors to reduce circuit impedance. Additionally, high-frequency transformers were employed to further increase the transmission voltage. A prototype was developed and tested, demonstrating an increase in transmission current at frequencies between 10 and 120 kHz with a peak active power of 200 W. Under the same transmission voltage, compared to the transmission circuit without impedance matching, the transmission current increased to a maximum of 16.7 times (average of 10.8 times), whereas compared to the transmission circuit using only traditional impedance matching, the transmission current increased by a maximum of 10.0 times (average of 4.2 times), effectively improving the exploration resolution.

A probabilistic interpretation of corrosion state through half-cell potential and electrical resistivity measures: The Flaminio Bridge in Rome

During the last decades, non-destructive investigation approaches have played an essential role in preserving structural integrity, capacity, and finding early defects in reinforced concrete (RC) heritage affected by time-dependent degradation. One of the most widespread structural RC damages belongs to corrosion phenomena. Electro-chemical approaches stand out among the non-destructive techniques presently available for identifying corrosive problems in-situ. The latter gives some knowledge in terms of physical quantities aiming to evaluate structural conditions by collecting indirect measures. Nevertheless, results are correlated to strong interpretative scale codes, which may not always provide appropriate interpretation of the defect's identity. In the paper a probabilistic degradation model, based on a statistical interpretation of the in situ electro-chemical measurements, has been proposed with the aim to give a contribution for structural diagnosis. Finally, results are validated through structural visual inspection.

Fiber optics passive monitoring of groundwater temperature reveals three-dimensional structures in heterogeneous aquifers

Alluvial aquifers often exhibit highly conductive embedded formations that can act as preferential pathways for the transport of solutes. In this context, a detailed subsurface characterization becomes crucial for an effective monitoring of groundwater quality and early detection of contaminants. However, small-scale heterogeneities are seldom detected by traditional nondestructive investigations. Heat propagation in porous media can be a relatively inexpensive tracer for groundwater flow, potentially offering valuable information in various applications. In this study, we applied passive Fiber Optics Distributed Temperature Sensing (FO-DTS) to a group of observation wells in a highly heterogeneous phreatic aquifer to uncover structures with different hydraulic conductivity, relying on their response to temperature fluctuations triggered by natural and anthropogenic forcings. A comprehensive data analysis approach, combining statistical methods and physics-based numerical modeling, allowed for a three-dimensional characterization of the subsurface at the experimental site with unprecedentedly high resolution.

In-situ detection on near-infrared spectra fingerprints of asphalt mixture after laboratory short- and long-term aging

Although Fourier transform infrared spectroscopy has been widely used in research on the aging of asphalt binders, it is a cumbersome, time-consuming, and environmentally polluting process using toxic solvents to extract and recover asphalt binders from asphalt mixtures for spectral measurement and analysis. However, little effort has been devoted towards its non-destructive spectral measurement, which is important for intelligent monitoring of pavement deterioration conditions. This paper focused on the non-destructive investigation of comparative near-infrared spectra of asphalt mixture specimens designed using the Marshall method after laboratory short- and long-term aging with a portable near-infrared spectrometer. The near-infrared spectra showed that asphalt mixtures from different aging states appeared significantly different fingerprints. The near-infrared fingerprints and aging states were also statistically significantly different according to the analysis of one-way analysis of variance. These distinctive near-infrared fingerprints could be attributed to the varied amounts of chemical functional groups, mainly hydrogen-containing groups during oxidative aging. This study provided a non-destructive and in-situ detection of the aging of asphalt mixtures.

Nondestructive Spectroscopic Investigation of N-Type 4H-SiC Defects Irradiated With Low Fluence 16.5 MeV/u Ta Ions

Nondestructive Spectroscopic Investigation of N-Type 4H-SiC Defects Irradiated With Low Fluence 16.5 MeV/u Ta Ions

Provenance of Neolithic Stone Artefacts through Minimally Invasive or Absolutely Non-Destructive Petroarchaeometric Investigations: Some Cases from Calabria (Southern Italy)

In the present work, more than one hundred and thirty lithic artefacts rediscovered in several archaeological sites dating from the Upper Palaeolithic to the Middle Ages from Calabria (Southern Italy) were petroarchaeometrically characterised through minimally invasive techniques. In more detail, 110 specimens were found in the Grotta della Monaca site (Sant’Agata di Esaro), and the other 23 belong to a collection kept in the Museo Nazionale Preistorico ed Etnografico “Luigi Pigorini” (Roma), coming from several localities (Longobucco, Spezzano della Sila, Cicala, Gimigliano, Roccaforte del Greco, and Bova). For preservation needs, 2 small axes in polished stone and 2 obsidians collected from Grotta della Monaca were analysed by absolutely non-destructive techniques. Optical and electron microscopic investigations, sometimes integrated with wavelength-dispersive X-ray fluorescence spectroscopy and X-ray diffraction spectrometry, allowed us to ascertain that the source area of all the lithic tools was in Calabria, except for obsidians, which come from the island of Lipari (Messina, Southern Italy). For a small number of particularly favourable cases, it was possible to define with great precision the outcrop area of the used rocks given their textural and mineralogical features. The specific source area contained a pickaxe originating from Cetraro–Fuscaldo metabasalt (lawsonite–albite facies) outcrops and two small axes in polished stone, one derived from migmatitic metapelites from Palmi and the other from meta-ultramafic rocks from Curinga. The choice of the used lithologies, harder or softer, had to be linked to the use that humans had to make of the lithic artefacts.

Non-destructive investigation of thermophysical properties on the China's space station: In-orbit experiment measurements and analysis

This paper discusses the current state of non-destructive research on the density, surface tension and viscosity of molten samples using the electrostatic levitation furnace (ELF) aboard the China Space Station (CSS). To address the challenges posed by the microgravity environment during the non-destructive testing process of containerless technology, we have developed several solutions. These include a temperature correction for infrared temperature measurement, a dual-camera position correction technique for density testing, a double electrode synchronous excitation, semi-frequency excitation and fine-sweeping approach for surface tension testing, and a signal demodulation method for viscosity testing. The uncertainties of the three thermophysical properties were 0.51 %, 3.10 %, and 9.78 %, respectively. This study highlights the feasibility and accuracy of measurements conducted in the ELF on the CSS, offering valuable insights into the behavior of molten materials under microgravity conditions. The findings from this study significantly contribute to our understanding of the thermophysical properties of molten materials.

Spectroscopic and imaging considerations of THz-TDS and ULF-Raman techniques towards practical security applications.

Nitrogen-containing high-energy organic compounds represent a class of materials with critical implications in various fields, including military, aerospace, and chemical industries. The precise characterization and analysis of these compounds are essential for both safety and performance considerations. Spectroscopic characterization in the far-infrared region has great potential for non-destructive investigation of high energetic and related compounds. This research article presents a comprehensive study of common organic energetic materials in the far-infrared region (5-200 cm-1), aiming to enhance security measures through the utilization of cutting-edge spectroscopic techniques. Broadband terahertz time-domain spectroscopy and ultra-low frequency Raman spectroscopy are employed as powerful tools to probe the vibrational and rotational modes of various explosive materials. One of the key objectives of this present work is unveiling the characteristic spectral features and optical parameters of five common nitrogen based high energy organic compounds towards rapid and accurate identification. Further, we have explored the potential of terahertz reflection imaging for non-contact through barrier sensing, a critical requirement in security applications. Based on the spectral features obtained from the spectroscopic studies and using advanced imaging algorithms we have been able to detect these compounds under various barriers including paper, cloth, backpack, etc. Subsequently, this study highlights the capabilities of the two techniques offering a pathway to enhance their utility over a wide range of practical security applications.

Non-destructive real-time monitoring and investigation of the self-assembly process using fluorescent probes

Fluorescent probes for detecting complex environments in vivo play an important role in self-assembly in vitro.

Metodologias para avaliação da integridade estrutural de cúpulas e abóbadas históricas em alvenaria

Abstract Modern non-destructive investigation techniques and computational tools for nonlinear analysis allow understanding the structural behavior and damage of existing buildings, aiming at the least possible extent of intervention. Careful and minimal intervention is essential to preserve the authenticity of the built cultural heritage. An investigation with a historical, experimental, and numerical approach was carried out in the Theatro Municipal do Rio de Janeiro, in Brazil, a building with an eclectic architecture from the beginning of the twentieth century. Its masonry domes and vault have paintings by renowned artists on their intrados and were strengthened in the 1970s. The adopted methodology was based on anamnesis, characterization and observation of the structure employing non-destructive tests, and on the assessment of its vulnerability by nonlinear analyses of calibrated numerical models. Several hypotheses of differential settlement under gravitational actions were investigated, seeking to reproduce the cracking pattern and to identify the causes of damage to the masonry domes and vault before the strengthening. The nonlinear analysis of the structure allowed to evaluate the causes of the observed damage, assess the level of safety, identify the most vulnerable parts, and characterize the collapse mechanisms, in addition to demonstrating the efficiency of the intervention measures adopted in the past.

Comparative Non-Destructive Investigations of the Effects of Structural Changes After Heat Treatment of Carbon Steel Samples by Magnetic Noise and Vibration Methods

The microstructure of some components that work for a long time at high temperatures changes, which leads to a reduction in their life cycle. Traditionally, the study of the resulting structures is carried out by mechanical tests and metallographic analysis. The application of non-destructive methods increases the possibilities to monitor the quality of the elements and to prevent destruction. The aim of the study is to detect changes in the microstructure after different heat treatment and ageing heating of materials via magnetic noise and vibration methods. To realize the goal, samples of high-quality medium carbon steel were prepared through targeted heat treatments, quenching and tempering at different temperatures, as well as ageing heating at temperatures of 700 o C for up to 16 hours by vibration and magnetic noise method. The natural frequencies and damping properties of forced longitudinal vibrations of various heat treated steel specimens were obtained and analyzed. Using magnetic noise method, the following parameters were obtained and analyzed: root mean square voltage (RMS), energy and envelope parameters of magnetic noise signals. The comparative application of several non-destructive methods increases the knowledge of methods and materials and makes it possible to establish their sensitivity in studying microstructural characteristics.

Process Intensification and Performance Assessment of Sputtered Gadolinium Doped Ceria (GDC) Barrier Layer in Large-Area Solid Oxide Fuel Cell Short Stack

In recent years, Gadolinium Doped Ceria (GDC) barrier layers have been reported to enhance the performance of Solid Oxide Fuel Cells (SOFCs)by reducing cathode/electrolyte interface diffusion and improving ionic conductivity. Prior investigations have demonstrated that GDC thin film sputtered at room-temperature yields substantial enhancements in Solid Oxide Fuel Cells (SOFCs).This enhancement is evidenced by a noteworthy increase in output current (+78%) and a considerable reduction in ohmic resistance (up to -42%), compared to conventionally screen-printed industrial SOFCs. To probe the intricate interplay between morphology and stoichiometry, which fundamentally determines the Ce3+/Ce4+ ratio governing both ionic and electronic conductivity, this study utilized quantitative X-ray Photoelectron Spectroscopy (XPS) and X-ray Absorption Spectroscopy (XAS) techniques. Results revealed that annealing parameters played a role in the number of available oxygen vacancies in the oxygen-reduction reaction (ORR), inducing different changes in the investigated samples. Non-destructive investigations utilizing Distribution of Relaxation Time (DRT) analysis were conducted on two short stacks with varying thickness, employing different sputtering Modalities. These studies revealed that thickness significantly influences the ultimate performance.

Towards Safer Batteries- 4D Imaging of Abuse Mechanisms in Lithium-Ion Batteries Using Synchrotron X-Ray Computed Tomography

Higher energy density materials are being pushed by the research community to make lithium-ion batteries a better competitor to chemical fossil fuels for transport applications. This increases potential risk of lithium-ion batteries and therefore safety investigations are highly important for application purposes. Operando Computer Tomography provides a non-destructive investigation method of different abuse mechanisms.Application of X-ray computed tomography (XCT) for studying lithium-ion batteries has gained interest among the research community especially in the past decade [1]. This technique is widely used for ex-situ samples to measure porosity and tortuosity [2], particle size and volume distribution [3] in the graphite anode as well as different cathode materials such as LiCoOx and NiMnCoOx. [4]. In situ measurements of commercial batteries are also often carried out to detect defects induced in a cell by a safety abuse test or manufacturing process [5]. Operando CT of large cells (for example 18650 form factor) is conducted at synchrotron facilities with high flux of high energy photons, however at a cost of details due to the large field of view [6].Thanks to their high brilliance, synchrotron beam facilitates us to do a full Computed Tomography in a short time. This enables us to measure batteries while being cycled with a reasonable time resolution to record morphological changes. In this presentation we illustrate how one can utilize this ability to investigate abuse mechanisms on an actual commercially available lithium-ion battery from cell level to electrode level.In this work, lab-based and synchrotron X-ray computed tomography is applied to commercial lithium-ion batteries. It is shown how to find most suitable imaging settings to study available lithium-ion batteries on different size scales, from cell level to particle level. We also demonstrate how to optimize contrast as well as both temporal and spatial resolutions to study in-situ and operando processes in a commercial battery using attenuation and phase contrast SXCT. Manufacturing defects and inconsistencies on cell level as well as the electrode and microstructure on material level are shown in our study.Using the presented methodic, some abuse conditions are induced and imaged in operando on a commercially available li-ion battery. In this work, deep discharge mechanism is visualized and quantified in detail for the first time in 4 dimensions.This oral presentation is aimed to present SXCT and lab XCT imaging as an important tool for studying state of safety of lithium-ion batteries from cell level down to particle level. It is shown how to find most suitable imaging settings to study available lithium-ion batteries on different size scales. We also demonstrate how to optimize contrast as well as both temporal and spatial resolutions to study in-situ and operando processes in a commercial battery using attenuation and phase contrast SXCT. Manufacturing defects and inconsistencies on cell level as well as the electrode and microstructure on material level are shown in our study. Moreover, some abuse conditions are imaged in operando in a commercially available li-ion battery. Le Houx, J. and D. Kramer, X-ray tomography for lithium ion battery electrode characterisation — A review. Energy Reports, 2021. 7: p. 9-14. Eastwood, D.S., et al., The application of phase contrast X-ray techniques for imaging Li-ion battery electrodes. Nuclear Instruments and Methods in Physics Research Section B: Beam Interactions with Materials and Atoms, 2014. 324: p. 118-123. Finegan, D.P., et al., Investigating lithium-ion battery materials during overcharge-induced thermal runaway: an operando and multi-scale X-ray CT study. Phys Chem Chem Phys, 2016. 18(45): p. 30912-30919. Ebner, M., et al., Tortuosity Anisotropy in Lithium-Ion Battery Electrodes. Advanced Energy Materials, 2014. 4(5). Patel, D., et al., Thermal Runaway of a Li-Ion Battery Studied by Combined ARC and Multi-Length Scale X-ray CT. Journal of The Electrochemical Society, 2020. 167(9). Finegan, D.P., et al., In-operando high-speed tomography of lithium-ion batteries during thermal runaway. Nat Commun, 2015. 6: p. 6924.

Diagnosis of Wall Structure of Mural Painting in Josadang Shrine of Buseoksa Temple Using High-Resolution GPR Exploration

The National Treasure Mural Painting in Josadang Shrine of Buseoksa Temple is a Goryeo Dynasty mural painted on a wall made of clay. GPR exploration, a non-destructive investigation method , was conducted to determine whether the cause of wall cracks was related to the frame. A method of transmitting electromagnetic waves with a high frequency of 2 GHz through the surface of the mural was applied, and HH and VV data were acquired in the Y-axis direction. The survey was conducted with high resolution by setting the measurement line interval to 1 cm and the data acquisition interval to 1 cm very closely. The exploration method is similar to rebar exploration commonly used at construction sites. However due to the nature of earthen walls and wooden structures, they produce weak reflection signals, so when the data is processed in the same way, noise is amplified in the image. This may lead to errors in interpreting the results. In data processing, images were derived by applying the optimal gridding method. As a result of the investigation, it was determined that the wall framework was composed of Gasisae, Seol-oe, and Nul-oe that can be seen in a Korean Hanok building, and it was confirmed that wall cracks occurred on the location of the Gasisae.

Condition Assessment of Heritage Buildings via Photogrammetry: A Scoping Review from the Perspective of Decision Makers

In recent years, advanced digital technologies have driven an outstanding paradigm shift in the field of architectural heritage, particularly for building modelling, historical documentation and touristic promotion. Nonetheless, they show great potentialities in the field of assessment and control of the state of conservation of heritage buildings. In particular, close-range and aerial photogrammetry have increasingly relied on low-cost and user-friendly tools and procedures, with a high degree of automation that makes them accessible to specialists who are foremost involved in architectural diagnosis and conservation, rather than in remote sensing sciences. In this framework, this paper provides a scoping review of 117 publications, based on the PRISMA protocol, from Scopus and Web of Science databases, related to the employment of photogrammetric models and methods, with specific focus on the targets and purposes of the diagnostic process, including decay mapping, structural monitoring and modelling, non-destructive investigation and multi-source documentation. In detail, the results point out that current studies mainly support robust processing of large amounts of information from direct observation of surface alterations, systematic correlation between materials, construction characteristics, visible anomalies and experimental measurements, as well as multi-disciplinary collaborative workflows through remote inspection and harmonized data management. Further improvements were identified, including standardization of acquisition procedures, automatization of elaboration pipelines, integration of real-time data, validation of diagnosis decision-making support tools and scalability to networks of assets.

A multi analytical characterization of a small bronze figurine from Gran Carro site (Bolsena Lake, Italy)

This paper presents the results of an archaeometric analysis carried out on an early Iron Age anthropomorphic figurine discovered in the area of the Gran Carro on Bolsena Lake (Latium, Italy) site, currently interpreted as a place of worship. This statuette is considered a unicum, both because of the context in which it was found and because of its stylistic characteristics similar to those of bronzes from the Nuragic civilization (Sardinia, Italy). Its discovery and the data obtained from this work provide further evidence in support of numerous previous studies suggesting the presence of trade and direct exchanges between Sardinia and southern Etruria. The research was performed through some non-destructive investigations such as Energy Dispersive X-Ray Fluorescence (EDXRF) combined with Monte Carlo Simulation (MC) and micro-invasive investigations such as Scanning Electron Microscopy coupled by Energy Dispersive Spectroscopy (SEM–EDS) and by Electron Probe Micro-Analysis (EPMA), metallography and lead isotope analyses (LIA), performed on a selected micro-fragment. The combination of non-destructive techniques (EDXRF-MCS) for the characterization of the artefact allowed us to obtain data similar to those obtained with micro-invasive surveys, further demonstrating the effectiveness of the method. The results indicate that the statuette is made of a bronze alloy and that the copper metal was extracted from Sardinian deposits.

Review on Analysis Methods Enabled by Hyperspectral Imaging for Cultural Relic Conservation

In this review, the conservation methods for various types of cultural relics enabled by hyperspectral imaging are summarized, and the hyperspectral cameras and techniques utilized in the process from data acquisition to analyzation are introduced. Hyperspectral imaging is characterized by non-contact detection, broadband, and high resolution, which are of great significance to the non-destructive investigation of cultural relics. However, owing to the wide variety of cultural relics, the utilized equipment and methods vary greatly in the investigations of the associated conservation. Previous studies generally select a single type of cultural relic for conservation. That is, seldom study has focused on the application of hyperspectral techniques to generalized conservation methods that are simultaneously suitable for different types of cultural relics. Hence, some widely used hyperspectral cameras and imaging systems are introduced first. Subsequently, according to the previous investigations, the methods used for image acquisition, image correction, and data dimensionality reduction in hyperspectral techniques are described. Thirdly, a summary of methods in cultural relic conservation based on hyperspectral techniques is presented, which involves pigments, grottoes and murals, and painting and calligraphy. Later, some challenges and potential development prospects in hyperspectral-based methods are discussed for future study. Finally, the conclusions are given.

Defect detection for industrial neutron radiographic images based on modified YOLO network

Neutron radiography (NR) has been widely used in non-destructive investigations. Since the industrial neutron radiographic images (NRIs) usually suffer from unclear defect features, insufficient data volume, and low efficiency of manual detection, we propose a proof-of-concept defect-detection method based on the modified YOLO network for the degraded NRIs in this paper. Firstly, 6336 radiographic images including crack, inclusion, blow hole, and residual core are built as the defect-detection dataset. Secondly, the types and the relative coordinates of defects are labeled by a graphical image annotation tool (i.e., Labelimg). Finally, the adaptive spatial feature fusion (ASFF) and convolutional block attention module (CBAM) are introduced to the modified YOLO network to enhance its ability of small-size defect detection. Experimental results demonstrate that the proposed method can achieve the average accuracy of 98.1% and detection rate of 85.985 frames per second (FPS) with a single NVIDIA GeForce RTX 4090 GPU on the built radiographic image dataset. In addition, the proposed method shows a good potential in detecting the above defects contained in the real NRIs.