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A complete simulation chain for the laser-based generation of a microfocus-size gamma ray beam of multi-MeV energy range able to produce radiographic images has been developed. The major interactions needed to obtain such a beam are treated individually. Particle-in-cell is used to study the generation of the electron beam through laser wake-field acceleration (LWFA), and Geant4 is employed for the Bremsstrahlung photon emission and for testing the imaging capabilities of the generated gamma beam. The paper presents detailed discussions about the implementation of each simulation, along with the results obtained. The structure of the article walks through the LWFA of up to 100 MeV electron beam, followed by its attenuation through a tantalum foil generating a 300 μ m spot size photon beam, later used for imaging of a thick lead test-object, assessing a 100 μ m resolution, and confirming the simulated imaging setup suitability for non-destructive testing applications of thick high-density objects. An analysis of the quality control parameters for the generated image along with discussions of possible improvements is also included. [ABSTRACT FROM AUTHOR]

Mode coupling and conversion between longitudinal and transverse modes are ubiquitous and universal in elastic waves, presenting a challenge in realistic applications such as nondestructive evaluation and geological exploration, where independent and separate manipulation of each mode is demanded. In this article, we propose a design of elastic metalens that can realize a high-efficiency focusing for the longitudinal wave and a V-shaped converging pattern for the transverse wave at the same time. The metalens is constructed from a metagrating, where each meta-atom has a simple configuration and renders high diffraction efficiency even for large steering angles, enabled by concurrent utilization of grating diffraction theory and advanced optimization algorithms. Interestingly, an arbitrary energy splitting ratio between the reflected longitudinal and transverse waves can be obtained by precisely controlling the coupling strength and conversion efficiency between them, providing improved flexibility and adaptability to various application environments. Two illustrative examples with a sharp focusing effect and tailored conversion efficiency are explicitly demonstrated, with a 50/50 energy splitting ratio between the longitudinal and transverse waves in the first case, and a 70/30 ratio in the second one. [ABSTRACT FROM AUTHOR]

The targeted concentration of acoustic waves has significant implications for industrial nondestructive testing, ultrasound diagnosis, and medical treatment. Most conventional sound-focusing metasurfaces suffer from an untunable focus, narrow bandwidth, and fixed geometric configurations, which severely constrain their practical utility. In this paper, we propose a reconfigurable acoustic coding metasurface composed of two coding units with high transmittance and transmitted phases of 0 and π for realizing tunable and broadband sound focusing. Through the straightforward manipulation of each unit structure and alterations in the coding sequences, precise control of the focus position across the entire working plane is attainable, enabling both tunable axial-axis and off-axis sound-focusing effects. Moreover, the sound-focusing performance of the proposed metasurface is excellent within a broad frequency range from 3000 to 5500 Hz. The experimental results are consistent with theoretical expectations and numerical simulations. This work lays a practical foundation for the design of acoustic devices for tunable and broadband sound focusing. [ABSTRACT FROM AUTHOR]

The swift progress in portable spectrometer technology has fostered a widespread need for compact light sources. Concurrently, near-infrared phosphor-converted light-emitting diodes (NIR pc-LEDs), characterized by their low cost and compact structure, emerge as an optimal choice. Inspired by phase optimization through fluxes, we successfully synthesized pure phase Lu 3 Mg 2 GaSi 2 O 12 (LMGS):Cr3+, 3 wt%MgF 2 luminescent materials by incorporating various fluxes including LiF, NaF, MgF 2 , CaF 2 , SrF 2 and BaF 2. These materials emit broadband NIR light ranging from 620 nm to 1150 nm, with full width at half-maximums (FWHMs) exceeding 125 nm. By employing a dual-fluxes strategy to further enhance the luminescence intensity of Cr3+, the LMGS:3%Cr3+, 1 wt%NaF, 2 wt%MgF 2 sample exhibits a 2.45 times increase in emission intensity compared to the LMGS:3%Cr3+, 3 wt%MgF 2 sample. Concurrently, the quantum efficiency rises from 24 % to 46 %. Moreover, the integrated emission intensity of LMGS:3%Cr3+, 1 wt%NaF, 2 wt%MgF 2 retains at 75 %@425 K of its value at RT. Upon coupled with a 430 nm LED chip, the luminescent material exhibits an NIR output power of 43.8 mW@300 mA, indicating promising applications in rapid night identification, night vision and non-destructive testing. By adding different fluxes, the luminescence intensity of LMGS:Cr3+ is achieved a stepwise enhancement. [Display omitted] [ABSTRACT FROM AUTHOR]

This study contributes to the fields of nondestructive testing (NDT) and structural health monitoring (SHM), which are pivotal for extending the service life of infrastructure and aligning with sustainability goals in construction. The study emphasizes an advanced application of the deformation area difference (DAD) Method, focusing on the comparative analysis of curvature lines derived from photogrammetry‐assisted deflection measurements and direct strain measurements. The novel strain area difference (SAD) method is presented. The research includes numerical simulations and practical experiments. A laboratory experiment with a steel beam demonstrates the method's effectiveness by comparing curvature lines from strain and deflection data. Additionally, an on‐site application on a composite bridge using photogrammetry and drone technology is described with a comparative numerical analysis. The investigations' results shed light on the potential of integrating diverse data sources in NDT/SHM practices. For instance, the integration of deflection measurements and strain measurements for SHM. The comparative analysis provides crucial insights into the accuracy and applicability of the DAD and SAD method in various structural scenarios, improving the precision of condition assessments in reinforced concrete structures. The findings have significant implications for the sustainable maintenance and operation of infrastructure. They support efficient decision‐making in the maintenance and repair of structures, contributing to their longevity and reducing the need for extensive interventions. They present a robust framework for decision‐making in predictive maintenance. [ABSTRACT FROM AUTHOR]

This paper delves into a significant area of research, exploring the application of the standard boundary element method (BEM) to analyze inverse acoustic frequency scattering problems in 2D space using a rigid corrugated circular object. The inverse problem is reformulated as an optimization problem, with the boundary of the scatterer parametrized to reduce the number of optimization variables. The influence of these parameters on imaging results based on near-field data is examined. The analysis uses a flat wave illuminating the object along the positive x-axis direction. The study evaluates the accuracy of the solution across various parameters defining the boundary of the analyzed object. The findings, which significantly contribute to advancements in computational methods, non-destructive testing, and the understanding of functional properties of materials and structures, offer valuable insights into numerical techniques and their practical engineering applications. [ABSTRACT FROM AUTHOR]

Terahertz time-domain spectroscopy is a widely used non-contact detection technology with significant potential in the field of non-destructive testing. In this study, the transfer function of the coating system is derived based on the Rouard model and the refractive index of the coating within the transfer function is modelled using the Debye model. The hierarchical thickness of the multilayer composite material is fitted by random optimisation algorithm. Considering the complexity of the objective function and the practical accuracy requirements in engineering problems, the integer genetic algorithm is adopted to find the optimal parameters. The comparison of the ordinary genetic algorithm and the integer genetic algorithm reveals that the integer genetic algorithm requires a significantly smaller population size and computation time than the ordinary genetic algorithm. Furthermore, the predicted thickness obtained by the integer genetic algorithm is more repeatable, has higher computational efficiency, and exhibits smaller errors. Our results indicate that combining the integer genetic algorithm with the Rouard model holds potential applications in thickness measurement of multilayer composite materials. [ABSTRACT FROM AUTHOR]

Nowadays, composite materials have become prevalent across various sectors, particularly finding usage in large-scale applications such as spaceships, automobiles, and aircrafts. The accurate detection of the defects in these materials is crucial, yet traditional methods often rely on human inspection, which is susceptible to errors. Recent advancements in machine learning have enabled defect detection using ultrasonic non-destructive testing methods. This paper introduces a new dataset named UNDT, which is obtained from the scans of 60 different composite materials, generating a total of 1150 images depicting both defective and non-defective areas. Several transfer learning methods are applied on the newly introduced UNDT dataset as well as the publicly available USimgAIST ultrasonic dataset. Comparative performance assessments illustrate the significance of utilising the transfer learning approach for defect classification on ultrasonic inspection images. Furthermore, the research emphasises the substantial benefits of employing these transfer learning methods. Notably, the DenseNet121 and VGG19 models achieve the highest accuracy rates, with 98.8% and 98.6% on the UNDT and USimgAIST datasets, respectively. [ABSTRACT FROM AUTHOR]

Exploring a non-destructive and rapid evaluation method for precious ancient ceramic relics is of significant importance. Currently, there are countless monochrome porcelain fragments awaiting measurement and categorization. Various instruments such as XRF, XRD, SEM, OM, and thermoluminescence dating have been extensively utilized by numerous researchers to study ancient ceramics. However, these techniques pose challenges in reliably identifying monochrome porcelain fragments from the same kiln with similar appearance, content, and microstructure due to their limitations. To address this issue, this study presents an acoustic measurement system that utilizes audible frequencies to non-destructively evaluate monochrome porcelain fragments. The proposed method enables the extraction of parameters related to time domain analysis (e.g., group delay), frequency domain analysis (e.g., resonance), and sound loss characteristics of these fragments. This non-destructive and efficient technology for detecting acoustic characteristics of monochrome porcelain fragments presented in this work clarifies the fundamental principles governing the interaction between sound waves and ancient ceramic fragments while providing a completely non-destructive and highly efficient method for classifying and restoring valuable solid cultural heritages like stone, jade, bronze etc. Moreover, this approach can also be applied for non-destructive testing of elastic modulus in advanced ceramic devices including detecting small cracks, deterioration effects due to aging as well as other defects. [ABSTRACT FROM AUTHOR]

Highlights Low‐thickness/diameter cylindrical storage pressure vessels with composite overwrapping fail at diverse internal and external pressure circumstances, causing several faults that must be included and minimized to retain effectiveness and working capability. The bursting effect is caused by hoop (internal) stresses and can be reduced by composite lamination alignment and internal pressure resistance. Pressure vessel bursting faults vary with internal tensions and can induce fiber reinforced polymer fracture and composite cylinder failure under many failure criteria. Micro‐mechanical nondestructive testing uses independent failure criteria associated to modes like Tsai‐Wu, Tsai‐Hill, Azzi‐Tsai, Hoffman, and Chamis. Micro‐cracking of composite layers generates delamination in composite pressure vessels, causing porosity. Pressure vessel micro‐cracking was assessed using classical laminate theory. Composite material strain‐rate failures in mobile applications like hydrogen storage cars with composite pressure vessels are examined due to their widespread use. Finally, Polar, Helical, and Hoop winding sequences are consistently focused to optimize the design and analyze the parameters for the overall impact of different failure aspects as bursting behavior in cylindrical composite pressure vessels. Type‐IV composite pressure vessels have the best results due to their lightest weight but complexity of winding over the polar head geodesic and non‐geodesic curvatures overwrapped carbon include all these internal composite and liner geometry faults and optimize them to reduce failure issues to fix composite overwrapped pressure vessels (COPV's) design. Liner‐less composite pressure vessels (Type‐V) need more design and production study for high‐pressure and temperature applications. Failure deals with the internal and external pressures exerted on composite pressure vessels. Failures like bursting of the pressure vessel, due to like micro‐cracking, delamination's and strain‐rate failures of composites. Failures detection through NDT inspection for polymer composite materials for composite pressure vessels. (COPV) perfect lamina sequence, liner materials and fiber winding angles must be considered for designing state of the art liner‐less Type‐V pressure vessels. Independent Failure criteria like (Tsai‐Wu & Hashin). [ABSTRACT FROM AUTHOR]

Highly accelerated lifetime test (HALT) for lifetime evaluation was performed on the state-of-art automotive MLCC prototypes by varying Dy/Mg (donor/acceptor) ratio added to BaTiO 3. The results clearly showed that the mean time to failure (MTTF) more than 280 times as the Dy/Mg ratio increased from 1.0 to 10.0. Since oxygen vacancies typically form in-gap state/defect at the donor level, the activation energy value under thermal activation process as a function of voltage was calculated and compared by non-destructive testing (I – V curve) for an accurate evaluation of the extrinsic behavior. It was found that barrier height at the Ni/BT interface decreases as the voltage increases, resulting in a decrease in activation energy. As the Dy/Mg ratio increases, the density of defects/in-gap states formed at the donor level in the bandgap by oxygen vacancies decreases, which may lead to a decrease in the number of electrons excited by the external voltage. Furthermore, it was verified that the calculated Schottky barrier height of the 10.0 Dy/Mg ratio under voltage has higher value than that of the 2.6 Dy/Mg ratio. Based on the results of this study, we propose a new indicator for the design of automotive MLCCs with high lifetime reliability that can be used for comparative analysis of additive compositions through non-destructive test (I – V curve) with low evaluation time/cost. [Display omitted] [ABSTRACT FROM AUTHOR]

The non-destructive testing for subsurface damage of processed silicon nitride ceramics is significant to the improvement of processing technology and evaluation of product performance. A novel method for the measurement of subsurface damage based on dispersion of laser-excited surface acoustics wave is proposed in this paper. The subsurface damage distribution is quantified as the damage density and depth of the damage layer. The forward model of surface acoustics wave propagation in damage layer is derived by the stiffness matrix method. Bayesian inversion is applied to estimate model parameters and uncertainties of subsurface damage from the experimental dispersion data. Laser ultrasonic experiments are carried out on four samples with different substrate material parameters and surface qualities to demonstrate the feasibility of the method for detecting varying degrees of subsurface damage. The results prove that with reasonable use of prior information about damage depth predicted by surface roughness, subsurface damage with a depth ∼10 times smaller than the minimum wavelength of surface acoustics wave is accurately characterized. The reliability of the results is further verified by Vickers microhardness tester. [ABSTRACT FROM AUTHOR]

Additive manufacturing (AM) defects present significant challenges in fiber-reinforced thermoplastic composites (FRTPCs), directly impacting both their structural and non-structural performance. In structures produced through material extrusion-based AM, specifically fused filament fabrication (FFF), the layer-by-layer deposition can introduce defects such as porosity (up to 10–15% in some cases), delamination, voids, fiber misalignment, and incomplete fusion between layers. These defects compromise mechanical properties, leading to reduction of up to 30% in tensile strength and, in some cases, up to 20% in fatigue life, severely diminishing the composite's overall performance and structural integrity. Conventional non-destructive testing (NDT) techniques often struggle to detect such multi-scale defects efficiently, especially when resolution, penetration depth, or material heterogeneity pose challenges. This review critically examines manufacturing defects in FRTPCs, classifying FFF-induced defects based on morphology, location, and size. Advanced NDT techniques, such as micro-computed tomography (micro-CT), which is capable of detecting voids smaller than 10 µm, and structural health monitoring (SHM) systems integrated with self-sensing fibers, are discussed. The role of machine-learning (ML) algorithms in enhancing the sensitivity and reliability of NDT methods is also highlighted, showing that ML integration can improve defect detection by up to 25–30% compared to traditional NDT techniques. Finally, the potential of self-reporting FRTPCs, equipped with continuous fibers for real-time defect detection and in situ SHM, is investigated. By integrating ML-enhanced NDT with self-reporting FRTPCs, the accuracy and efficiency of defect detection can be significantly improved, fostering broader adoption of AM in aerospace applications by enabling the production of more reliable, defect-minimized FRTPC components. [ABSTRACT FROM AUTHOR]

In this work, a hydrometallurgical process for the recycling of diamond core drilling crowns by means of aqua regia leaching and subsequent alkali leaching was investigated. This investigation continues a previous study in which nitric acid was used for the acid leaching phase. In the current study, higher tungsten recovery was achieved, reaching 98.2%, which is an improvement of about 1.5%. Another advancement of this study was the high Co recovery (97.21%) and the high purity of the tungsten trioxide obtained, comparable to the previously proposed technological process. Furthermore, a novel laboratory method for testing recycled diamond drilling crowns based on infrared thermography was introduced. Although this innovative approach is not the most accurate, it is fast and cost-effective and provides valuable results before the actual field test is conducted as a final evaluation. In addition, the infrared thermography method offers the advantage of non-destructive testing, ensuring that the diamond drilling crowns can be assessed without compromising their structural integrity. Other instrumental methods used to characterize the products and intermediates were X-ray diffraction (XRD), scanning electron microscope with energy dispersive X-ray spectroscopy (SEM-EDS), and laser desorption ionization mass spectrometry (LDI-MS). The analytical method for the concentrations in all working solutions was ICP-AES. [ABSTRACT FROM AUTHOR]

Research of peach fungal gummosis (PFG), which is a vascular disease caused by fungi in the Botryosphaeriaceae family, is particularly important in the southeastern United States, southern China, South Africa, and Western Australia. This disease has been a significant concern for the peach industry in the southeastern United States since the 1970s. The changing climatic conditions in the prunus production areas of the world have worsened the severity of PFG disease. A study of the morphological and genetic profiles of Botryosphaeriaceae species from diseased peach trees found four species in Georgia, Florida, Alabama, and South Carolina. Botryosphaeria dothidea, Lasiodiplodia theobromae, Diplodia seriata, and Neofusicocoum parvum were isolated and identified using conidiospore characters and rDNA sequences of internal transcribed spacer regions and elongation factor a-1 genes. B. dothidea was the most common species from diseased peach trees. A significant implication of this research is the potential resistance in Prunus germplasm, which was genotyped for the resistance locus Botd8 and evaluated for relative susceptibility to one isolate each from B. dothidea, L. theobromae, and D. seriata. Pathogenicity evaluations of peach, almond, and interspecific hybrids used detached stem and leaf assays for susceptibility to PFG based on lesion lengths and gumming scores. L. theobromae inoculation resulted in the most extensive lesions on stems and leaves. Detached stem and leaf assays indicated that Prunus with the Botd8 locus significantly differed in lesion size when infected with B. dothidea and D. seriata. However, the resistant locus had no significant effect on the relative susceptibility of Prunus to L. theobromae. Field and detached stem and leaf assays identified almond cultivars Pioneer and Golden State and Peach × Almond hybrids with Botd8 (+) as tolerant to PFG. Correlations between detached assays and field gumming scores suggested that inoculations on detached stems or leaves under controlled conditions can be used to preliminarily screen for resistance to PFG. These detached assays for specific pathogen isolates provide an opportunity for a relatively fast, nondestructive evaluation of Prunus germplasm and are tools that can be used to identify the components of disease resistance. [ABSTRACT FROM AUTHOR]

The document provides a comprehensive list of upcoming international conferences, workshops, and symposiums related to materials, corrosion, and related fields. Events are scheduled in various countries such as Germany, India, the United States, and Canada, covering topics like non-destructive evaluation, corrosion inhibition, and materials engineering. The calendar spans from December 2024 to September 2027, offering a diverse range of opportunities for professionals and researchers in the field to engage and collaborate on cutting-edge developments. [Extracted from the article]

Purpose: The objective of this study is to use non-destructive testing of corrosion on coated aluminium alloys using differential eddy current detection (DECD), with the aim of elucidating the relationship between the characteristics of corrosion defects and the detection signal. Design/methodology/approach: Pitting corrosion defects of varying geometrical dimensions were fabricated on the surface of aluminium alloy plates, and their impedance signals were detected using DECD to investigate the influence of defect diameter, depth, corrosion products and coating thickness on the detection signals. Furthermore, finite element analysis was used to ascertain the eddy current distributions and detection signals under different parameters. Findings: The size of the defect is positively correlated with the strength of the detection signal, with the defect affecting the latter by modifying the distribution and magnitude of the eddy current. An increase in the diameter and depth of corrosion defects will enhance the eddy current detection (ECD) signal. The presence of corrosion products in the corrosion defects has no significant effect on the eddy current signal. The presence of a coating results in a decrease in the ECD signal, with the magnitude of this decrease increasing with the thickness of the coating. Originality/value: The objective is to provide experimental and theoretical references for the design of eddy current non-destructive testing equipment and eddy current testing applications. [ABSTRACT FROM AUTHOR]

Study of gamma-backscattered peaks is important for the estimation of composition, density, defects and thickness of the scattering materials. In the present study, gamma rays from a point source of 137Cs were scattered onto materials of different atomic numbers and NaI(Tl) scintillator detector was used for collection of backscattered events. It is observed that the area under the backscattering peak is dissimilar for materials of different atomic numbers with variable thickness. Simulation of the experiment was carried out using GEANT4 for the validation of the experimental findings. [ABSTRACT FROM AUTHOR]

Inspection of thick and low-density multilayer composite structures is of paramount importance. X-ray computed tomography (CT) and phased array ultrasonic testing (PAUT) are widely employed modalities for non-destructive testing (NDT) of these composites. Owing to low density of constituent materials typically utilised to construct composites and rich wave scattering within their structures, inspecting them using X-ray CT and PAUT does not always yield acceptable flaw detection results. On the other hand, microwave NDT techniques have shown to be particularly suitable for inspecting thick multilayer non-carbon-based composites. However, the relative performance of emerging microwave NDT techniques and the widely accepted X-ray CT and PAUT is yet to be established. This paper provides first-of-its-kind experimental comparison between microwave, X-ray CT, and PAUT on a comprehensive set of thick composite samples with different defect types. It is demonstrated herein that microwave NDT performed on par with X-ray CT in terms of defect detection capability (qualitatively and quantitatively), and in many cases outperformed PAUT. A detailed summary overviewing the performance, advantages and shortcomings of each method for particualr defect types is included which disseminates new knowledge to benefit practitioners and researchers alike. [ABSTRACT FROM AUTHOR]

An ultrasonic Rayleigh wave detection method is proposed to determine the geometrical characteristics of subsurface small-scale fractures in concrete. A three-dimensional observation system, including an inclined wedge ultrasonic device, is used to obtain the Rayleigh wave wide-angle data to exhibit the azimuth-dependent scattered wave field. The anisotropic characteristics of Rayleigh wave transmission coefficient are used to determine the distribution range and dip angle of fractures. Fracture models in concrete with different dip angles are designed, and the dip angle is correlated with the degree of attenuation (transmission coefficient) anisotropy. The transmission coefficient characteristics are presented in a random observing system. A focusing approach can be adopted to distinguish the subsurface fracture and to verify the reliability and flexibility of the surface wave approach in practice. The tendencies of experimental results are consistent with patterns obtained from numerical simulation. The proposed method has important application prospects for the non-destructive testing of complex invisible fractures in concrete. [ABSTRACT FROM AUTHOR]

Distributed point source method (DPSM) has been gradually applied to the field of nondestructive testing (NDT). As a semi-analytical modelling technique, DPSM is extremely powerful and straightforward for solving various engineering problems, such as ultrasonic fields and electromagnetic field. In this paper, the technique is extended to model the eddy current field including sweep frequency measurement and scanning defect. The configuration of eddy current sensors consists of excitation coil and solid-state magnetic field measurement sensors such as Hall device and giant magnetoresistive sensor. Besides that, the wave propagation has been described and magnetic field created by eddy current has been calculated. The results obtained by DPSM is compared with that calculated by finite element method (FEM) in terms of accuracy and computation time, which indicates DPSM can improve calculation speed while ensuring calculation accuracy. [ABSTRACT FROM AUTHOR]

Wood is a multiscale heterogeneous natural composite material with properties depending on its growing conditions and its genetic heritage. This variability is challenging for industries that work to perform homogeneous and reliable products. In industry, different non-destructive testing methods are in use to classify, grade, and select wood products to optimize their usage. Among them, the use of lasers to detect fiber orientation with different wavelengths. This orientation significantly influences the mechanical behavior of wood, including stress limits and stiffness. According to our knowledge, the use of laser diffusion still is limited to grain angle measurement. Our objective in this paper is to realize transmission light scattering maps for wood samples from several wood species (poplar, oak, Douglas fir, beech), and then identify the most suitable wavelength to study light diffusion in wood, depending on the property that will be measured. A supercontinuum laser is used over a wavelength range from 500 to 800 nm, allowing precise adjustment of the wavelengths. It was found that near-infrared light better scatters in the studied wood species than lower wavelength. However, the wavelength that gives the best contrast between earlywood and latewood depends on the sample studied and is not necessarily in the near infrared rays. [ABSTRACT FROM AUTHOR]

Reliable performance of the electricity distribution networks is critical to avoid outages and disruptions which may lead to substantial economic losses. Some of the important components of the electricity distribution networks include overhead cables, utility poles, cross-arms, substations, and transformers. These components are subjected to deterioration with aging and pose risks of failure creating safety concerns, specially under extreme weather conditions. Efficient maintenance and the use of accurate condition assessment techniques to monitor the integrity of the aforementioned components are key factors to be considered in managing the electricity distribution assets. This article presents a review of different condition assessment techniques employed for monitoring the electricity distribution infrastructure. The conventional inspection techniques and advancements in non-destructive testing methods are discussed outlining the relative advantages and disadvantages. Other than the normal failures of distribution infrastructure due to component ageing, unexpected and less frequent extreme weather events can have significant impacts on the resilience of the electrical power infrastructure. Thus, the effects of extreme weather conditions on the reliability of the electricity distribution networks and the failure rates of assets are reviewed in this study. Further, the maintenance and decision-making approaches implemented in the power distribution networks are also discussed. [ABSTRACT FROM AUTHOR]

Corrosion in reinforced concrete structures is among the major degradation mechanisms. The quantification and description of the spatial distribution of the corrosion condition within a structure on the basis of condition assessments are important. This study considered half-cell potential mapping data as a widely used technique to detect corrosion in reinforced concrete structures. A four-step workflow was proposed to analyse half-cell potential data with geostatistical techniques, first consisting of trend identification and possible trend removal. The obtained residuals were then subjected to a quantile-quantile transformation. Subsequently, experimental variograms were calculated and fitted with variogram models to estimate the correlation lengths. A case study with data from a road tunnel confirms the applicability of the workflow. It was assumed that the identified trend is primarily a result of the heterogeneity of the exposure conditions within the structure that ranges several metres. The residuals are interpreted as the result of the heterogeneities of material resistances that give rise to spatial variability in corrosion probability on a shorter distance range. The proposed analysis may be utilised for service life modelling (e.g. based on random fields), planning maintenance works, or optimising the grid size for half-cell potential measurements. [ABSTRACT FROM AUTHOR]

Quality control and grading of Korla fragrant pears significantly impact their commercial value. Rapid and non-destructive detection of soluble solids content (SSC) and firmness is crucial to improving this. This study proposes a method combining near-infrared spectroscopy (NIRS) with machine learning for the rapid, non-destructive detection of SSC and firmness in Korla pears. By analyzing absorbance in the 900–1800 nm range, six preprocessing methods—Savitzky–Golay derivative (SGD), standard normal variate (SNV), multiplicative scatter correction (MSC), Savitzky–Golay smoothing (SGS), vector normalization (VN), and min-max normalization (MMN)—were applied to the raw spectral data. uninformative variable elimination (UVE) and successive projections algorithm (SPA) were then used to extract effective wavelengths. Partial least squares regression (PLSR) models were developed for SSC and firmness based on the extracted data. The results showed that all preprocessing and wavelength-extraction methods improved model accuracy. The optimal SSC prediction model was MSC-SPA-PLSR (R = 0.93, RMSE = 0.195), and the best hardness prediction model was MSC-UVE-PLSR (R = 0.83, RMSE = 0.249). This research aids in establishing a non-destructive testing system, offering producers a rapid and accurate quality assessment tool, and provides the food industry with better production control measures to enhance standardization and market competitiveness of Korla pears. [ABSTRACT FROM AUTHOR]

The traditional probability of detection (POD) method, as described in the Department of Defense Handbook MIL-HDBK-1823A for nondestructive evaluation systems, does not take the time dependency of data collection into account. When applied to in situ sensors for the measurement of flaw sizes, such as fatigue-induced crack length and corrosion-induced mass loss, the validity and reliability of the traditional method is unknown. In this paper, the POD for in situ sensors and their associated reliability assessment for detectable flaw sizes are evaluated using a size-of-damage-at-detection (SODAD) method and a random parameter model (RPM). Although applicable to other sensors, this study is focused on long-period fiber gratings (LPFG) corrosion sensors with thin Fe–C coating. The SODAD method uses corrosion-induced mass losses when successfully detected from different sensors for the first time, while the RPM model considers the randomness and difference between mass loss datasets from different sensors. The Fe–C coated LPFG sensors were tested in 3.5 wt.% NaCl solution until the wavelength of transmission spectra did not change. The wavelength shift of 70% of the tested sensors ranged from 6 to 10 nm. Given a detection threshold of 2 nm in wavelength, the mass losses at 90% POD are 31.87%, 37.57%, and 34.00%, which are relatively consistent, and the upper-bound mass losses at 95% confidence level are 33.20%, 47.30%, and 40.83% from the traditional, SODAD, and RPM methods, respectively. In comparison with the SODAD method, the RPM method is more robust to any departure from model assumptions since significantly more data are used. For the 90% POD at 95% confidence level, the traditional method underestimated the mass loss by approximately 19%, which is unconservative in engineering applications. [ABSTRACT FROM AUTHOR]

The goal of this research was to determine the appropriate parameters for welding two-phase duplex stainless steel (DSS) and to understand the challenges involved in the process. For welding pipes with diameters of ø25 mm and ø38 mm of steel type 1.4462, the classic tungsten inert gas (TIG) method and TIG with a toroidal shielding gas nozzle were used. The aim was to improve the durability and service life of welded joints produced using the toroidal shielding gas nozzle compared to those produced using traditional TIG methods for DSS welding. The welding process was carried out using the parameters: arc voltage 9V, welding current 105A for TIG and 80A with a toroidal shielding gas, welding speed 90 mm/min for TIG and 95 mm/min with a toroidal shielding gas. The welded elements were tested for quality properties. Tests such as visual, penetration, radiographic, and destructive tests (macroscopic, ferrite content, hardness, microscopic, diffraction, static strength, and fatigue) were conducted on the test samples prepared in the TIG process. The actual test results were compared to the acceptable values from the standards. Using a toroidal nozzle in the welding process had lowered the ferrite content in the surface layers by about 10% in comparison to the traditional TIG method. The morphology and phase arrangement of the tested welded joints varied significantly, even when utilizing a toroidal nozzle. The analysis of the determined durability showed that welding with a toroidal shielding gas nozzle provided superior results, with enhancements ranging from 4% to 132%. Furthermore, the use of a toroidal nozzle reduced gas consumption by 17% for each joint type compared to conventional welding. In terms of service life, the joints welded with a toroidal nozzle demonstrated nearly twice the longevity of those welded with traditional methods. [ABSTRACT FROM AUTHOR]

Carbon fiber laminates are susceptible to impact damage due to the lack of fibers in the direction of impact. Often such damage can be difficult to find with visual assessment, prompting the need for detection via nondestructive testing techniques. This study quantifies the ultrasonically characterized impact damage diameters in 22 layered CFRP samples from 16 J, 18 J, 20 J, 22 J, and 24 J impact energies. These energies result in damage often defined as barely visible impact damage. This study utilizes x-ray computed tomography as a baseline to verify the results of the ultrasonic testing. Compression after impact test measurements are used in this study to find the ultimate compressive residual strength of the impacted carbon fiber laminates and to investigate the negative correlation between impact energy and residual mechanical properties of the damaged carbon fiber laminates. Many studies focus on the characterization of impact damage from various impact energies and setups via ultrasonic testing or, separately, the effect of the impact setups on the residual strength of the composite. This study strengthens the bridge between the barely visible impact damage quantified via ultrasonic testing and the residual compressive strength of the affected composite. Overall, this paper offers further insights into the relationship between internal damage size obtained using ultrasonic testing and correlates the characterized internal damage geometry to the resultant compressive strength reduction, providing a path for future studies in predictive modeling of the residual strength after impact. [ABSTRACT FROM AUTHOR]

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This study addresses the challenges of high costs and lengthy detection times associated with non-destructive testing of mechanical damage in apples. A novel approach combining deep learning and the Harris hawks optimizer (HHO) is proposed to tackle this. The study employs near-infrared relaxation spectroscopy to analyze apples' spectral characteristics in different conditions. These spectral data are then processed by a residual network (ResNet) to extract relevant features. The extracted features are subsequently fed into a fusion model comprising long short-term memory (LSTM) and an Attention mechanism, with the model's output determined by the Softmax function. The HHO is utilized to optimize parameter combinations for the search models, and its performance is compared against the gray wolf optimization algorithm whale optimization algorithm (WOA), and dwarf mongoose optimization algorithm. Moreover, the study introduces the Multiple Measurement Classification Recognition (MMCR) method to enhance accuracy. Comparative analyses demonstrate that the HHO-ResNet-LSTM (Attention)-MMCR model effectively captures intricate nonlinear relationships, resulting in an impressive accuracy increase to 98%. This innovative model offers a promising avenue for non-destructive fruit inspection, contributing to the advancement of inspection methodologies. [ABSTRACT FROM AUTHOR]

Achieving non-destructive detection of aflatoxin in peanuts can prevent the processing of aflatoxin-contaminated peanuts into food products. A potential non-destructive electrical impedance spectroscopy method for aflatoxin B1 (AFB1) in peanuts is proposed. To research the relationship between electrical parameters and aflatoxins, this study analyzed the effects of improper storage duration on the content of aflatoxins and conducted experiments using impedance spectroscopy and NMR with different content of AFB1. Results showed that the aflatoxin content was proportional to the number of days of improper storage. The impedance Z could as an indicator for characterizing AFB1. The parameters of electrical impedance spectrum under multi-frequency (1000 Hz and 4 MHz) were better than those under the single frequency (1000 Hz or 4 MHz), and the combination of Z and θ showed the best correlation (R2 = 0.998). The detection mechanism was accurate under improper storage conditions, and aflatoxin production was accompanied by moldy kernel, leading to changes in endosperm structure and impedance. Our study informs the development of non-destructive detection devices for aflatoxins in peanuts. [ABSTRACT FROM AUTHOR]

The internal defects in rock masses can significantly impact the quality and safety of geotechnical projects. Mechanical waves, as a common nondestructive testing (NDT) method, can reflect the external and internal structures of rock or rock masses. Analyses on the reflected and transmitted waves enable nondestructive identification and assessment of potential defects within rocks. Previous studies mainly focused on the variation of single or limited wave features like main frequency, amplitude and energy between the intact and non‐intact samples. In fact, most information contained in the waveforms is neglected. Techniques of data mining can provide a powerful tool to reveal this information and therefore a more accurate determination of the internal structures. In this study, 995,412 NDT data from 14 types of granite and gypsum samples with different cross‐section shapes and different types of defects are recorded by an ultrasonic wave generation and collection system. This dataset can be used not only as the training data for defect classification in NDT but also as a good reference for conventional NDT analyses. Besides, time‐series data analysis is an opportunity and challenging issue, this dataset holds great potential for broader application in general time‐series classification analysis. [ABSTRACT FROM AUTHOR]

Structural health monitoring is essential for the lifecycle maintenance of tunnel infrastructure. Distributed fiber‐optic sensor (DFOS) technology, which is capable of distributed strain measurement and long‐range sensing, is an ideal nondestructive testing (NDT) approach for monitoring linear infrastructures. This research aims to develop a distributed sensing network utilizing DFOS for structural integrity assessment of concrete immersed tunnels. The primary innovations of this study lie in the development of a general flowchart for establishing a sensing network and obtaining reliable field data, as well as its subsequent validation through a detailed case study. Concentrated joint deformations in typical immersed tunnels, detectable by the DFOS, are key indicators of structural integrity. This study addresses crucial elements of field monitoring system design, including the selection of appropriate optical fibers or cables and the determination of vital interrogator system parameters. It also covers sensor parameter determination, installation techniques, field data collection, and postanalysis. Furthermore, this research is exemplified by a case study that illustrates the successful implementation of a distributed sensing network in an operational immersed tunnel, and monitoring data reveals cyclic structural deformations under impacts of daily tide and seasonal temperature variations. The data obtained from this network play a significant role in subsequent condition assessments of tunnel structures. The research findings contribute to the assessment of large‐scale infrastructure health conditions through the application of DFOS monitoring. [ABSTRACT FROM AUTHOR]

The damage process of composite materials, such as short fiber-reinforced plastics (SFRP), is complex. Therefore, it is necessary to accurately represent the damage process in fatigue life prediction. Herein, fatigue life prediction was conducted by combining the digital image correlation method, which is a non-destructive testing technique, with a convolutional neural network (CNN), using Xception as the network architecture. High prediction accuracy was obtained when training and testing were performed on the same SFRP specimens. In contrast, using different specimens for training and testing resulted in lower accuracy. This issue may be improved by increasing the number of specimens. The regions of interest in the model were visualized by Gradient-weighted Class Activation Mapping. Notably, the model indicated the breaking point as the region of interest from the early stages of the test. The breaking point was identified at an earlier stage by the CNN than by visual inspection, demonstrating the potential for a new method of damage observation. [ABSTRACT FROM AUTHOR]

This study proposed a hydroponic system with the capacity to acquire high-resolution in situ mass data for non-destructive evaluation of water circulation in lettuce. The system customizes the watering profile, enables high-frequency in situ weight measurement, and monitors multidimensional environment changes. Key air, water, and light parameters were collected to evaluate the plant response, susceptibility, and adaptability to environmental conditions. Multiple physiological indices were defined to characterize the properties of two lettuce varieties in response to different environmental factors. [ABSTRACT FROM AUTHOR]

The preservation of the degrading transport infrastructure is vital, as replacing it is impossible in view of limited budgets and environmental impacts. One component in overcoming this challenge is the evaluation of the reliability and the calculation of the remaining service life of existing structures. These structural reliability reassessments allow for the identification and utilization of load‐bearing capacity reserves. The consideration of actual structural characteristics and environmental conditions, various of which can be gathered by means of numerous measurement and inspection techniques, has the potential for more realistic computation results and therefore more economic decisions about the operation as well as maintenance activities. This article attempts to shed light on the potential of nondestructive testing (NDT) methods for updating the input variables in the ultimate limit states during a recalculation. The approach of the NDT‐supported reliability reassessment is demonstrated using a prestressed concrete bridge emphasizing the bending proof in transversal direction. As a result, the semi‐probabilistic, probabilistic and NDT‐based reassessment results are compared and the effects of NDT‐supported structural analysis on the calculated reliability are highlighted. [ABSTRACT FROM AUTHOR]

The fundamental shear horizontal (SH0) guided wave transducer shows unique promise for non-destructive testing and structural health monitoring in oil pipelines, railway tracks, solar power plants, and beyond due to its non-dispersive characteristics. Under this background, it is desirable to explore the high-performance piezoelectric crystals to develop the SH0 guided wave transducers. Herein, a novel piezoelectric crystal KCsMoP2O9 (KCMP) with dominant face shear mode d14 was grown by Kyropoulos method and proposed to excite and receive the SH0 wave based on the finite element simulation. The resonance frequency was found to be 190 kHz with the designed size of 6 mm × 6 mm × 1.5 mm. The group velocity of generated wave packet was determined to be 3040 m/s, affirming that the detected signal was the SH0 wave. The simulated and experimental results demonstrated the exceptional ability of KCMP-based guided wave transducer to generate and detect obvious SH0 waves in two orthogonal principal directions over a wide frequency range (160–360 kHz). Additionally, the KCMP-based SH0 wave transducer showcases its excellent defect localization ability with high signal-to-noise ratio (~ 30 dB), demonstrating its great potential for application in non-destructive testing and structural health monitoring. [ABSTRACT FROM AUTHOR]

Most reported research for monitoring health of pipelines using ultrasonic guided waves (GW) typically utilize bulky piezoelectric transducer rings and laboratory-grade ultrasonic non-destructive testing (NDT) equipment. Consequently, the translation of these approaches from laboratory settings to field-deployable systems for real-time structural health monitoring (SHM) becomes challenging. In this work, we present an innovative algorithm for damage identification and localization in pipes, implemented on a compact FPGA-based smart GW-SHM system. The custom-designed board, featuring a Xilinx Artix-7 FPGA and front-end electronics, is capable of actuating the PZT thickness shear mode transducers, data acquisition and recording from PZT sensors and generating a damage index (DI) map for localizing the damage on the structure. The algorithm is a variation of the common source method adapted for cylindrical geometry. The utility of the algorithm is demonstrated for detection and localization of defects such as notch and mass loading on a steel pipe, through extensive finite element (FE) method simulations. Experimental results obtained using a C-clamp for applying mass loading on the pipe show good agreement with the FE simulations. The localization error values for experimental data analysed using C code on a processor implemented on the FPGA are consistent with algorithm results generated on a computer running Python code. The system presented in this study is suitable for a wide range of GW-SHM applications, especially in cost-sensitive scenarios that benefit from on-node signal processing over cloud-based solutions. [ABSTRACT FROM AUTHOR]

The inhomogeneity between cells is the main cause of failure and thermal runaway in Lithium-ion battery packs. Electrochemical Impedance Spectroscopy (EIS) is a non-destructive testing technique that can map the complex reaction processes inside the battery. It can detect and characterise battery anomalies and inconsistencies. This study proposes a method for detecting impedance inconsistencies in Lithium-ion batteries. The method involves conducting a battery EIS test and Distribution of Relaxation Times (DRT) analysis to extract characteristic frequency points in the full frequency band. These points are less affected by the State of Charge (SOC) and have a strong correlation with temperature, charge/discharge rate, and cycles. An anomaly detection characteristic impedance frequency of 136.2644 Hz was determined for a cell in a Lithium-ion battery pack. Single-frequency point impedance acquisition solves the problem of lengthy measurements and identification of anomalies throughout the frequency band. The experiment demonstrates a significant reduction in impedance measurement time, from 1.05 h to just 54 s. The LOF was used to identify anomalies in the EIS data at this characteristic frequency. The detection results were consistent with the actual conditions of the battery pack in the laboratory, which verifies the feasibility of this detection method. The LOF algorithm was chosen due to its superior performance in terms of FAR (False Alarm Rate), MAR (Missing Alarm Rate), and its fast anomaly identification time of only 0.1518 ms. The method does not involve complex mathematical models or parameter identification. This helps to achieve efficient anomaly identification and timely warning of single cells in the battery pack. [ABSTRACT FROM AUTHOR]

In the field of railroad safety, the effective detection of surface cracks is critical, necessitating reliable, high-speed, non-destructive testing (NDT) methods. This study introduces a hybrid Eddy Current Testing (ECT) probe, specifically engineered for railroad inspection, to address the common issue of "lift-off noise" due to varying distances between the probe and the test material. Unlike traditional ECT methods, this probe integrates transmit and differential receiver (Tx-dRx) coils, aiming to enhance detection sensitivity and minimise the lift-off impact. The study optimises ECT probes employing different transmitter coils, emphasising three main objectives: (a) quantitatively evaluating each probe using signal-to-noise ratio (SNR) and outlining a real-time data-processing algorithm based on SNR methodology; (b) exploring the frequency range proximal to the electrical resonance of the receiver coil; and (c) examining sensitivity variations across varying lift-off distances. The experimental outcomes indicate that the newly designed probe with a figure-8 shaped transmitter coil significantly improves sensitivity in detecting surface cracks on railroads. It achieves an impressive SNR exceeding 100 for defects with minimal dimensions of 1 mm in width and depth. The simulation results closely align with experimental findings, validating the investigation of the optimal operational frequency and lift-off distance for selected probe performance, which are determined to be 0.3 MHz and 1 mm, respectively. The realisation of this project would lead to notable advancements in enhancing railroad safety by improving the efficiency of crack detection. [ABSTRACT FROM AUTHOR]

Measurements monitoring the inductive coupling between oscillating radio-frequency magnetic fields and objects of interest create versatile platforms for non-destructive testing. The benefits of ultra-low-frequency measurements, i.e., below 3 kHz, are sometimes outweighed by the fundamental and technical difficulties related to operating pick-up coils or other field sensors in this frequency range. Inductive measurements with the detection based on a two-photon interaction in rf atomic magnetometers address some of these issues as the sensor gains an uplift in its operational frequency. The developments reported here integrate the fundamental and applied aspects of the two-photon process in magnetic induction measurements. In this paper, all the spectral components of the two-photon process are identified, which result from the non-linear interactions between the rf fields and atoms. For the first time, a method for the retrieval of the two-photon phase information, which is critical for inductive measurements, is also demonstrated. Furthermore, a self-compensation configuration is introduced, whereby high-contrast measurements of defects can be obtained due to its insensitivity to the primary field, including using simplified instrumentation for this configuration by producing two rf fields with a single rf coil. [ABSTRACT FROM AUTHOR]

Triboluminescence (TL) is an optical phenomenon in which light is emitted from the surface of a material when subjected to pressure or shear forces. Due to its potential applications in non-destructive testing, radiation sources, and spectroscopic probes, TL has garnered increasing attention over the past two decades. However, experimental observations in the infrared spectrum remain limited, and its emission mechanism has not yet been fully understood. In this study, significant emission in the near-infrared spectrum was experimentally observed from the tribo-pairs of Cr/YSZ and quartz/YSZ. The results indicate that the Tribo-Induced Near-Infrared Light Emission consists of three peaks, in which the 780 nm peak is related to the electronic transition between the 3d5/2 and 3d3/2 orbitals of Y3+ ions, while the 880 nm and 990 nm peaks can be attributed to hole centers and T-type centers in the intrinsic defects of YSZ, respectively. Additionally, experiments reveal that the Cr/YSZ tribo-pair exhibits a redshift of 11–18 nm at the 780 nm peak compared to the quartz/YSZ tribo-pair. To explain the cause of the redshift phenomenon, X-ray photoelectron spectroscopy and UV-Vis absorption spectroscopy were used to measure the energy level spacing between the 3d5/2 and 3d3/2 orbitals of Y3+ and the bandgap width of YSZ before and after friction, respectively. We found that the bandgap width of the doped YSZ decreases after friction, which is often accompanied by a reduction in the energy level spacing between the 3d5/2 and 3d3/2 orbitals of Y3+. The extent of the reduction in energy level spacing varies with different dopants, leading to the redshift phenomenon. [ABSTRACT FROM AUTHOR]

High-performance materials, such as carbon fiber laminates, are costly to manufacture and are often used in demanding environments requiring the use of high-resolution non-destructive testing (NDT) methods to confirm the integrity of the parts. One NDT method that has shown promise for qualifying carbon fiber laminates is the use of immersion ultrasound with spherically focused probes. However, many parts may not be submersible in an immersion tank due to size or material constraints. These parts must be scanned with contact transducers with inferior resolutions or with expensive and messy systems such as bubblers. This research presents the use of a novel housing system that allows for the use of focused immersion transducers in an out-of-tank portable ultrasonic scanning application. This work presents a comparison between scans taken using a custom high-resolution immersion system and scans taken using the presented housing. There are a wide variety of potential inspection applications for this novel system, and the present work focused on two specific applications: the quantification of the spatially varying adhesive thickness in bonded carbon fiber laminates and the quantification of foreign object inclusions in carbon fiber laminates. The results presented show that scans using the portable housing are comparable in quality to scans performed using an immersion system. Specifically, both inspection approaches had an average error of 0.04 mm when quantifying the adhesive thickness of a bonded composite, and for the foreign object detection, the error in quantifying the dimensions of the embedded foreign object was 0.1 mm and 0.2 mm for the immersion system and the portable inspection system, respectively. The demonstration was performed in a laboratory setting, but a discussion is provided for the necessary improvements needed to extend the system for use in field applications. [ABSTRACT FROM AUTHOR]

The detection of debonding defects in thin-walled adhesive structures, such as clad-iron/rubber layers on the leading edges of helicopter blades, presents significant challenges. This paper proposes the application of electromagnetic acoustic resonance technology (EMAR) to identify these defects in thin-walled adhesive structures. Through theoretical and simulation studies, the frequency spectrum of ultrasonic vibrations in thin-walled adhesive structures with various defects was analyzed. These studies verified the feasibility of applying EMAR to identify debonding defects. The identification of debonding defects was further examined, revealing that cling-type debonding defects could be effectively detected using EMAR by exciting shear waves with the minimum defect diameter at 5 mm. Additionally, the method allows for the quantitative analysis of these defects in the test sample. Due to the limited size of the energy exchange region in the transducer, the quantitative error becomes significant when identifying debonding defects smaller than this region. The EMAR identified debonding defects in clad-iron structures of rotor blades with a maximum error of approximately 15%, confirming its effectiveness for inspecting thin-walled adhesive structures. [ABSTRACT FROM AUTHOR]

The porous Ti/perovskite composites were prepared successfully by ultrasound-assisted infiltration method. The Cs–Pb–Br perovskite materials were prepared on a larger scale by the mechanical ball-milling using the CsBr and PbBr 2 as the precursors. The Cs–Pb–Br perovskites had high PL intensity and excellent stability, meanwhile, the complex phase transformation between CsPbBr 3 and Cs 4 PbBr 6 occurred during the ball-milling process. The green fluorescence emission of composites might be attributed to CsPbBr 3 embedded within Cs 4 PbBr 6 perovskite. By the space occupying method, the porous Ti materials were prepared by using the acicular urea as the pore forming. The optimal young's modulus (1.0851 GPa) and porosity (38.27 %) were obtained. Finally, the prepared Ti/perovskite composites had outstanding fluorescence property and high stability, showing the wide application prospect in the fields of the bioflourescence imaging and nondestructive testing fields. [ABSTRACT FROM AUTHOR]

We present the theory, concept and design of an efficient, megawatt coherent Cherenkov radiation source based on a two-dimensional periodic surface lattice (2D-PSL) cavity combined with a novel energy recovery system for the generation of highly efficient (> 50%) single-frequency radiation. We demonstrate the scalability of the transverse dimension of the 2D-PSL cavity of the Cherenkov source and thus the potential for efficient, continuous-wave, high-power (> 1 MW) operation; fundamental to the eventual realization of clean, fusion energy. These new sources, with the capacity to operate in the 0.1-10THz range, hold strong promise to address the long-standing "Terahertz gap". By combining a Cherenkov oscillator driven by a non-gyrating beam with an innovative four-stage depressed collector energy recovery system, the overall device efficiency can be increased to be competitive with gyrotrons in the requirements for heating and current drive in fusion plasma. In these Cherenkov devices, the frequency independence of the magnetic guide field enables advantageous frequency scaling without deployment constraints, making them especially attractive for high-impact applications in fusion science, turbulence diagnostics, non-destructive testing and biochemical spectroscopy. The novel energy recovery techniques presented in this paper have broad applicability to many electron-beam driven devices, bringing revolutionary potential to future THz source technologies. [ABSTRACT FROM AUTHOR]

Recent advancements in concrete technology focus more on increasing strength than durability. Concrete with good durability will withstand adverse conditions like frost, chloride penetration, sulfate assault, alkali-aggregate reaction, steel corrosion, etc., which will lower the strength of the concrete. Strength is vital, but so is durability. The present study examined and discussed the durability parameters of conventional concrete made with geopolymer aggregate (GPA) as a partial substitute for natural aggregate. Strength studies in this research found that the optimal level of substitution for natural coarse aggregate by GPA was 100% replacement to produce the performing concrete. Replacement of natural coarse aggregate by geopolymer aggregate exhibits 9%-15% higher compressive strength than natural aggregate concrete. The findings reveal that concrete with 100% geopolymer aggregate exhibits a compressive strength increase of 9%-15% over that of concrete made with natural aggregates. Ultrasonic pulse velocity measurements for geopolymer aggregate concrete range between 4 km/s and 4.5 km/s, indicating good quality according to IS specifications. Additionally, Rebound Hammer test results further support the enhanced quality of geopolymer aggregate concrete. However, the porosity of geopolymer aggregates results in a sorptivity that is 10%-30% higher than that of natural aggregate concrete. Despite this, the increased resistance to acid and sulfate attacks is noted, attributed to the strong bonding between geopolymer aggregates and the cement matrix. [ABSTRACT FROM AUTHOR]

Featured Application: The application referred to within the paper is the development of a centrifugal impeller that equips a pump destined for active thermal control systems (mechanically pumped fluid loop) of spacecrafts. The current paper addresses the challenges in manufacturing a critical component of a centrifugal pump for space active thermal control systems of satellites, namely, the closed centrifugal impeller. Compared to the classical technologies, there is an obvious advantage of additive manufacturing of closed impellers, due to the possibility of creating complex geometries, which boost the hydraulic performances of the part and, implicitly, of the pump. In this regard, the authors performed a comparative analysis between a closed impeller obtained by classical machining and three manufactured by additive technology (selective laser melting) by means of dimensional inspection, non-destructive testing, and experimental evaluation. The study performed here showed that the additively manufactured closed impellers exhibited similar hydraulic performances to the classical one, without the need for performing post-processing of internal surfaces. Also, in terms of dimensional and geometrical stability, the additively manufactured closed impellers were within the imposed tolerances, demonstrating the feasibility of obtaining such complex parts by using additive manufacturing. Subsequently, the allocated time for manufacturing decreased by 75% for the closed impellers manufactured by additive technologies, and the need for using four technological processes was decreased to only two, printing and post-processing. [ABSTRACT FROM AUTHOR]

The control of soft surrounding rock stability has always been a hot academic issue. Soft rock has poor stability and low strength, and the deformation of a soft rock tunnel becomes more serious after it is affected by water for a long time. In this paper, the Jintong Coal Mine is taken as the research object, and nondestructive immersion experiments are used to study the change in mechanical properties of rock after being affected by water. The FLAC numerical model is used to analyze the stress evolution characteristics of the surrounding rock after being affected by water, and the results of the study show that the water absorption of siltstone is always higher than that of coarse-grained sandstone, and the uniaxial compressive strength of siltstone and coarse-grained sandstone decreases by 54.59% and 67.99%, respectively, under a state of saturated water compared with that under a state of dryness. Influenced by a T-shaped surface, the maximum principal stress concentration area occurs in the rock layer below the T-shaped surface and outside the joint. Concentrations of maximum shear stress occur within the "T" channel. Vertical stress concentration zones occur at the higher ground level and the bottom of the slope. The maximum shear stress of the roof fluctuates before the face reaches the surface of the "1" section, and continues to increase with and continues to increase with the distance of the face. After entering below the surface of the "1" section, the maximum shear stress of the roof increases rapidly, and the influence range is about 24 m. The maximum shear stress distribution plays a dominant role in the stability of the surrounding rocks of the two roadways. We analyze the principle of high-strength economic support, propose a "four-in-one" surrounding rock control technology based on "controlled hydrophobicity, structural adjustment, district management, and gradient control", and propose a surrounding rock control scheme of district management. The measured data on site show that the roadway surrounding the rock is reasonably controlled. This provides a reference for the stable control of the surrounding rock of the roadway under similar conditions. [ABSTRACT FROM AUTHOR]