Detector Resolution Research Articles

Golay coded thermal wave imaging for inclusions inspection in titanium alloy (Ti-6Al-4V): an analytical study

Detecting and characterizing inclusions in metallic materials is crucial in nondestructive testing (NDT) and imaging to ensure structural integrity and reliability. In the field of nondestructive material assessment, infrared thermographic imaging is a well-established technology. This approach analyzes the thermal profile collected over a test specimen to find surface and sub-surface abnormalities. Infrared thermography has demonstrated rising interest in coded thermal excitation techniques and the accompanying data processing technologies in recent years. However, using coded excitations in thermal NDT is still uncommon. This research investigates the viability of using complementary Golay-coded excitation in active thermography. This unique method displays its usefulness in improving the detection sensitivity and resolution by efficiently minimizing the side lobes of the compressed pulse. The current analytical study demonstrates the flaw detection capability of Golay-coded thermal wave imaging (GCTWI) for analyzing titanium alloy materials with anomalies such as inclusions. The research replicates thermal wave propagation and interaction with various inclusion geometries and sizes at the same depths. Furthermore, a comparison study is done between GCTWI analytical and simulation models to validate these models. The correlation coefficient is used as a figure of merit to assess GCTWI’s ability to identify and precisely localize these inclusions. The results show that GCTWI has better fault detectability and spatial resolution capabilities, making it a viable approach for inclusion inspection. Overall, this study advances NDT and imaging approaches by proving the capability of GCTWI for the reliable and efficient identification of inclusions in Titanium Alloy (Ti-6Al-4V). The study’s findings can help to develop more effective inspection procedures for assuring and maintaining the structural integrity of Ti-6Al-4V components in various sectors, including aerospace, automotive, and biomedical engineering.

Development of a single photon emission microscope system with ∼200 μm spatial resolution

With a low-energy pinhole gamma camera, spatial resolution is primarily determined by the intrinsic spatial resolution of the imaging detector, the pinhole diameter, and the magnification ratio of the collimator. However, the pinhole diameter has traditionally been limited to around 1 mm due to manufacturing difficulties with tungsten. To overcome this limitation and enhance the spatial resolution of the pinhole gamma camera, we fabricated a pinhole with a diameter of 0.1 mm. This pinhole was then combined with a YAP(Ce) imaging detector to create an ultrahigh-resolution pinhole gamma camera. The imaging detector consisted of a 38 mm × 38 mm × 1 mm thick YAP(Ce) plate, optically coupled to a 2-inch square flat panel photomultiplier tube (FP-PMT) with a 1 mm thick light guide. The intrinsic spatial resolution of the YAP(Ce) imaging detector was approximately 1.4 mm FWHM for 60 keV gamma photons. The YAP(Ce) imaging detector was encased in a tungsten shield, and the 0.1 mm diameter pinhole collimator was positioned 100 mm from the imaging detector surface. With a magnification ratio of 10 at 10 mm from the pinhole center, the spatial resolution improved to approximately 0.2 mm (200 μm) at 10 mm from the pinhole center using the developed pinhole gamma camera. The system sensitivity was approximately 0.001%. High-resolution transmission images of various subjects were obtained. The developed ultrahigh-resolution pinhole gamma camera was named the “single-photon emission microscope.” This device will be valuable for applications requiring ultrahigh resolution in single-photon gamma or X-ray imaging.

Study of quasi-projectile properties at Fermi energies in 48\\documentclass[12pt]{minimal} \\usepackage{amsmath} \\usepackage{wasysym} \\usepackage{amsfonts} \\usepackage{amssymb} \\usepackage{amsbsy} \\usepackage{mathrsfs} \\usepackage{upgreek} \\setlength{\\oddsidemargin}{-69pt} \\begin{document}$$^{48}$$\\end{document}Ca projectile systems

A systematic analysis of the data obtained by the FAZIA collaboration during a recent experiment with a neutron rich projectile is presented. The main goal was to compare the experimental results with the HIPSE event generator simulations to investigate the influence of the neutron rich entrance channel on the quasi-projectile fragment properties. The full isotopic range of charged particles detected in this experiment was within the limit of the resolution of the FAZIA detector. A majority of quasi-projectile fragments were detected thanks to the forward angular acceptance of the experimental setup which was confirmed through the HIPSE calculations. Essentially, the lowering of N/Z of quasi-projectile fragments with the beam energy was found to be present since the initial phase of the reaction. Thus, pre-equilibrium neutron emissions might be a possible candidate to explain such an effect.

Precise measurement of chiral spectrum in the ultraviolet band using weak measurement and a deep neural network model.

Circular dichroism (CD) spectrum and optical rotation (OR) spectrum, crucial for understanding molecular properties and configurations, present challenges due to limited testing methods and equipment accuracy in the ultraviolet (UV) region. This study proposes a weak measurement system for chiral signals in varying concentrations in the ultraviolet range, optimized using a deep neural network (DNN) model. Introducing different post-selections to detect the circular dichroism spectrum and optical rotation spectrum separately, with contrast as a probe, it achieves a detection resolution of up to 10-6 rad. Moreover, the fitted value of the training data can reach 0.9989, enhancing the prediction accuracy of chiral molecule concentrations. This method exhibits considerable promise for applications in chiral measurement and sensor technologies.

High sensitivity metasurface sensor for estimating the complex permittivity of ionic liquids

In this paper, a sensor based on a metasurface structure for the complex permittivity of ionic liquids is designed. The structure consists of an F4B substrate with a metal resonance pattern, and a polystyrene foam box is used to contain the ionic liquids to achieve non-contact measurements. The simulation results show that without the presence of the ionic liquids, the sensor can achieve a significant reflection spectrum depth of −37 dB at 11.2 GHz, after adding the ionic liquids, the sensor can generate different responses depending on the types of ionic liquids in the frequency range of 8–9.3 GHz. Furthermore, by employing a characteristic matrix model inversion based on the relationships between the complex permittivity, resonance frequency, and quality factor variations, the standard deviations of the real and imaginary parts of the complex permittivity for seven ionic liquids are estimated to be 0.18 and 0.3, respectively. The estimated results show a good agreement with the standard values obtained from probe measurements. The sensor designed in this paper features a small size, simple structure, and low fabrication cost. With a volume of 0.216 milliliters of the sample, it achieves a high sensitivity of 462.87 MHz/ԑ′and frequency detection resolution of 391.57 MHz/ԑ′. It demonstrates excellent discriminatory detection capability for ionic liquids, providing a new direction for the application research of metasurfaces.

Application of opposing coils transient electromagnetic method in urban area with metal interference

Opposing coils transient electromagnetic method (OCTEM) adopts small and weak-coupling transmitting-receiving coils configuration, which helps to reduce side effect and improve the detection resolution. With such advantages, it has been widely used for shallow sub-surface target detection. However, when the method is used in urban area, measured data may be distorted by electromagnetic (EM) interference from nearby metal objects. In practical application, it is necessary to perform modelling to provide guidance for measuring data analysis. Two OCTEM application cases in detecting shallow sub-surface karst caves in urban area with metal objects nearby are presented in this paper. Corresponding modelling are carried out to study the interference effect of the nearby metal objects. The first application case is about the EM interference of a vertical steel tower, of which the influence distance reaches up to 9 m by modelling. The second application case is about the EM interference of a thin aluminum fence, of which the influence distance reaches up to 6 m by modelling. Only when the observation is outside the influence zone, the metal influence can be ignored. When the measurement is inside the influence zone, the metal influence cannot be ignored. However, as the nearby metal objects mainly affects the early data, the subsurface target may also be detected in condition that the target response is stronger than the metal interference, or the target response time window is wider than that of the metal interference.

Ultra‐low power consumption flexible sensing electronics by dendritic bilayer MoS2

AbstractTwo‐dimensional transition metal dichalcogenides (2D TMDs) are promising as sensing materials for flexible electronics and wearable systems in artificial intelligence, tele‐medicine, and internet of things (IoT). Currently, the study of 2D TMDs‐based flexible strain sensors mainly focuses on improving the performance of sensitivity, response, detection resolution, cyclic stability, and so on. There are few reports on power consumption despite that it is of significant importance for wearable electronic systems. It is still challenging to effectively reduce the power consumption for prolonging the endurance of electronic systems. Herein, we propose a novel approach to realize ultra‐low power consumption strain sensors by reducing the contact resistance between metal electrodes and 2D MoS2. A dendritic bilayer MoS2 has been designed and synthesized by a modified CVD method. Large‐area edge contact has been introduced in the dendritic MoS2, resulting in decreased the contact resistance significantly. The contact resistance can be down to 5.4 kΩ μm, which is two orders of magnitude lower than the conventional MoS2 devices. We fabricate a flexible strain sensor, exhibiting superior sensitivity in detecting strains with high resolution (0.04%) and an ultra‐low power consumption (33.0 pW). This study paves the way for future wearable and flexible sensing electronics with high sensitivity and ultra‐low power consumption.image

Nuclear emulsion film production system for experiments in full-area scanning and analysis era

Research utilizing the sub-micron three-dimensional spatial resolution of nuclear emulsion detectors has been expanding in various fields, triggered by the development of automated emulsion scanning technology. This paper describes a new production system capable of supplying several thousand square meters of nuclear emulsion film per year. The development and introduction of improved emulsion gel, knife coating, and drying equipment have enabled the mass production of double-side coated nuclear emulsion films with thick emulsion layers suitable for full-area scanning and analysis. This system has played an essential role in numerous nuclear emulsion experiments.

Detection of Underground Utility Pole Base for Distribution Transmission Network Based on Transient Electromagnetic Method

In the construction of overhead distribution network lines, ensuring the stability and construction quality of utility pole foundations is crucial. Traditionally, this process may involve excavation and direct inspection, which is not only time-consuming but may also cause environmental damage. The non-destructive detection scheme proposed in this paper, based on the transient electromagnetic method (TEM), offers an efficient and non-intrusive method for detecting the burial conditions of utility pole bases, pulls, and chucks. The transient electromagnetic method is a geophysical exploration technique that uses the principle of electromagnetic induction to detect the distribution of underground materials. When detecting utility pole bases, this method analyzes the electromagnetic response generated by underground metallic structures to obtain information. However, traditional TEM has a blind zone problem in shallow metal detection, which limits its application in utility pole base inspection. To address this issue, the scheme proposed in this paper introduces a decoupling coil to eliminate interference caused by the primary magnetic field. This decoupling technology significantly improves the detection discrimination, allowing for a more accurate determination of the burial depth and condition of bases, pulls, and chucks. Finite element numerical analysis using COMSOL 5.4 is adopted to examine the underground magnetic field distribution and optimize coil parameters. This analysis helps to understand the interaction between the electromagnetic field and underground structures, guiding the design of coils and the development of detection strategies. The prototype experimental platform built further validates the effectiveness of the scheme. Experimental results include measured data of magnetic field variations, assessments of detection depth and resolution. These experimental results are crucial for verifying the practical application potential of the non-destructive detection scheme.

Development of an ultrahigh resolution 1 mm Si-PM array based GGAG alpha particle imaging detector with gamma or X-ray separation capability

For precise distribution measurements of alpha particles, as required in alpha radionuclide therapy research, a high-resolution alpha particle imaging detector is desirable. While combining a thin scintillator with a photodetector array, such as a position-sensitive photomultiplier (PSPMT), is a potential method to develop an event-by-event-based alpha particle imaging detector, the spatial resolution is currently limited to around 0.8 mm FWHM. To overcome this limitation, we utilized a small-sized Si-PM array combined with a thin GGAG plate to create an alpha particle imaging detector and evaluated its performance. In the developed alpha particle imaging detector, a Si-PM array with a channel size of 1 mm × 1 mm arranged in an 8 × 8 configuration was optically coupled to a 1 mm thick GGAG plate, with a 1-mm-thick light guide between them. Since the decay times of GGAG differ between alpha particles and gamma photons or X-rays, we were able to separately measure the distributions of alpha particles and gamma photons using pulse shape discrimination. The spatial resolution of the developed alpha particle imaging detector was 0.19 mm FWHM, and the energy resolution was 11% FWHM for 5.5 MeV alpha particles. Additionally, we were able to separately measure the distributions of alpha particles and gamma photons for simultaneously irradiated phantoms using pulse shape discrimination. The developed imaging detector shows promise for distribution measurements of alpha particles, as well as gamma photons or X-rays, where high spatial resolution and separation of gamma photons or X-rays are required.

Visible-Light Spectroscopy and Rock Magnetic Analyses of Iron Oxides in Mixed-Mineral Assemblages

Iron oxide assemblages are central to many pursuits, ranging from Mars exploration to environmental remediation. Oxides and oxyhydroxides of iron both carry the special properties of color and magnetism. In this paper, we use visible-light spectroscopy and rock magnetic data collected at varying temperatures (~77–973 K) to analyze the concentrations and identities of iron oxides found in natural hematite-dominated samples that were obtained from a scientific drill core of Late Triassic red beds in the American Southwest. Our results suggest that hematite colorization of Earth materials varies from red to blue/purple as crystal size increases. Second-derivative analysis of the collected visible-light spectra allows this variation to be measured through the characteristic wavelength band position. Magnetic coercivity data indicate “hardness” differences that also may suggest smaller grain sizes are associated with redder colors. Yellowish maghemite and goethite have overlapping characteristic wavelength band positions that make it challenging to distinguish their contributions to mixed assemblages from visible-light data alone. Remanent magnetizations acquired at ~77 K and room temperature suggest the presence of hematite and a low-coercivity phase that may be maghemite and/or oxidized magnetite. However, we interpret this phase as maghemite in order to explain the changes in iron oxide concentrations indicated by visible-light intensities near ~425 nm and because the thermal demagnetization data suggest that goethite is absent from the samples. Future research that increases the resolution of hematite, maghemite, and goethite detection in experimental and natural samples will provide opportunities to refine the study of past climates and constrain soil iron availability under future changes in global moisture and temperature. Multimethod datasets improve understanding of environmental conditions that cause iron oxides assemblages to shift in phase dominance, grain size, and crystallinity.

Response of a high-pressure 4He scintillation detector to nuclear recoils up to 9 MeV

Helium-4-based scintillation detector technology is emerging as a strong alternative to pulse-shape discrimination-capable organic scintillators for fast neutron detection and spectroscopy, particularly in extreme gamma-ray environments. The 4He detector is intrinsically insensitive to gamma radiation, as it has a relatively low cross-section for gamma-ray interactions, and the stopping power of electrons in the 4He medium is low compared to that of 4He recoil nuclei. Consequently, gamma rays can be discriminated by simple energy deposition thresholding instead of the more complex pulse shape analysis. The energy resolution of 4He scintillation detectors has not yet been well-characterized over a broad range of energy depositions, which limits the ability to deconvolve the source spectra. In this work, an experiment was performed to characterize the response of an Arktis S670 4He detector to nuclear recoils up to 9 MeV. The 4He detector was positioned in the center of a semicircular array of organic scintillation detectors operated in coincidence. Deuterium–deuterium and deuterium–tritium neutron generators provided monoenergetic neutrons, yielding geometrically constrained nuclear recoils ranging from 0.0925 to 8.87 MeV. The detector response provides evidence for scintillation linearity beyond the previously reported energy range. The measured response was used to develop an energy resolution function applicable to this energy range for use in high-fidelity detector simulations needed by future applications.

Vernier-effect based sensor with a reflective structure combining a pair of polarization-maintaining fibers

Temperature and strain may be the most common physical parameters involved in daily life and industrial world. Along with the rapid progress of modern society, people have made growing demands for higher sensitivities in temperature and strain measurements. This paper proposes a Vernier-effect based sensor with a reflective structure combining a pair of polarization-maintaining fibers for temperature and strain measurements, with high sensitivities in view. Theoretical analyses suggest that the high sensitivities can be readily achieved just by adjusting the lengths of the two polarization-maintaining fibers. Experimental results have corroborated the feasibility of the proposed sensor in both temperature and strain measurements, showing high sensitivities of −51.744 nm/°C and 838.2 pm/μɛ, respectively, with their minimum detection resolutions determined as 0.002 °C and 0.167 μɛ, respectively. Moreover, the compensation for temperature influence in strain measurements has been proven to be effective. Additional investigations have demonstrated the high stability of the proposed sensing system, as well as the fast response in strain measurements. Significantly, the proposed sensor features a simple structure with ease of fabrication, thus being highly desirable in daily life and industrial world.

Photonic stepped-frequency radar with 150-m unambiguous detection and centimeter range resolution.

Photonic stepped-frequency radars based on optical frequency-shifting modulation have shown attractive properties such as wide bandwidth, centimeter range resolution, inherent frequency-time linearity with low spectrum spurs, and reduced system complexity. However, existing approaches typically exhibit meter- or centimeter-level radar range ambiguity, inversely proportional to the frequency step, due to the large frequency shift determined by acousto-optic or electro-optic (EO) modulators. Here, we overcome this limitation by injecting a narrowband, stepped-frequency signal into an optical frequency-shifting fiber cavity to achieve, for the first time, to our knowledge, a broadband photonic stepped-frequency radar with 150-m unambiguous detection and centimeter range resolution, surpassing the reported photonic- and electronic-based counterparts. The demonstrated approach effectively resolves the trade-off between ambiguity range and shifting frequency while maintaining the signal quality and bandwidth, bringing its practicality into reach for outdoor applications.

Calculation of efficiency and resolution of a hexagonal NaI(Tl) detector as a function of source position

Most gamma-ray scintillation detectors currently in use are made from inorganic materials that have a relatively high electron density. Quite often they are used to build multidetector systems that provide high scintillation light output. The performance of a gamma radiation detector (its detection efficiency) depends on the shape and size of the crystal, as well as on the source-to-detector geometry used. The NaI(Tl) gamma detector exhibits moderate energy resolution but relatively high gamma-ray detection efficiency and fast time response. In this work, the efficiency and resolution of a scintillation hexagonal detector are studied to optimize its response function. This type and size of scintillator were selected to construct a budget-friendly, reconfigurable, easy-to-maintain multidetector system for registering gamma-rays following fission, capture, and inelastic neutron scattering reactions, with reasonably good energy and time resolutions The research results made it possible to establish a geometric solid angle that increases the efficiency of recording gamma-ray radiation of the hexagonal NaI(Tl) scintillation probe under study.

Predicting damage location information based on single actuator sensor path information using regularised multilinear regression

In structural health monitoring with guided ultrasonic waves, probability reconstruction algorithms are a method to locate a damage. They work by calculating the probability for each actuator sensor path on whether there is a damage on the path or not. By superposition of each path and its damage probability, a damage localisation is done. The disadvantage of this is, that the damage localisation resolution is limited by the number of paths crossing each other. To overcome this, the hypothesis of this investigation is that the information of a path can not only be used to determine whether a damage is present, but that additional information about the location within the path can be calculated as well. This way a localisation resolution can be higher than by only relying on the path density. To verify this assumption, an experimental setup was chosen in which the path lengths always remain the same while the distance between damage and the direct path varies. This is implemented by a moving ultrasonic microphone simulating the sensor. The varying distance is the local information, which is determined in this study using the information of a single path. For this purpose, a prediction is calculated using regularised multilinear regression. The input features are characteristic values of five sections of the sensor signal in the time domain. The sections are manually chosen based on arriving wave events. The result confirms the hypothesis. Therefore, it is plausible to increase the detection resolution of probability reconstruction algorithms by calculating damage location estimations for each path.

EpiXact-ONT: Long-read whole genome sequencing for rapid outbreak detection and comprehensive plasmid transmission analysis

Background: Healthcare associated infections (HAIs) are a major contributor to patient morbidity and mortality. HAIs are increasingly important due to the rise of multidrug resistant pathogens which can lead to deadly nosocomial outbreaks. Traditional methods for investigating transmissions are slow, costly and have poor detection resolution. In addition, plasmid transmission which can horizontally transfer critical resistance and virulence genes is not part of routine infection control practice due to lack of comprehensive and cost-effective methods capable of identifying both pathogen and/or plasmid transmission. Here we demonstrate the utility of the Oxford Nanopore Technologies (ONT) platform for whole genome sequencing (WGS) based pathogen and plasmids transmission analysis. Methods: We developed a rapid end-to-end process that includes sample preparation, sequencing optimized for generating long-reads and bioinformatics workflow customized for error-prone ONT data. We use Flye to generate de novo assemblies and a secondary bioinformatics step to identify each circular sequence. Individual circular sequences with an Ori (≥1) are identified. For pathogen clonality analysis we perform a pairwise mapping-based chromosomal sequences comparison eliminating need for an external reference genome. Similarly, individual plasmids are separated and compared pairwise. We annotate both the circularized chromosomal and plasmid sequences for known resistance and virulence genes. Results: We performed ONT (and confirmatory Illumina) sequencing of the genomes of 20 bacterial isolates originating from 5 HAI investigations previously performed at Day Zero Diagnostics using epiXact®, our Illumina-based HAI sequencing and analysis lab service. ONT-based clonality determination had 100% agreement with the Illumina based pipeline. We also found that using the outbreak-specific assembled genomes instead of an external reference increased the SNP-calling resolution in the ONT pipeline. We also identified sets of clonal isolates with both identical plasmids and distinct plasmids; as well as sets of non-clonal isolates with identical plasmids and distinct plasmids. In one subset of 7 multi-species isolates, we identified 2-7 circularized plasmid sequences in each isolate, all harboring known resistance genes. 4 plasmids were found in multiple isolates, with each plasmid appearing in between 2 and 4 distinct isolates. Notably, blaNDM was identified in at least 1 plasmid in each isolate. Conclusion: We demonstrate the utility of ONT for comprehensive HAI investigations, establishing the potential to transform healthcare epidemiology with rapid outbreak determination covering pathogen and plasmid transmission in < 2 4 hours from sample receipt.

INTEGRATION OF MACHINE LEARNING-BASED DETECTION SYSTEMS INTO AUTONOMOUS VEHICLES

The incorporation of machine learning (ML) driven detecting systems into autonomous vehicles (AVs) signifies a revolutionary advancement in contemporary transportation. The present study investigates the use of ML systems, namely in the domains of traffic sign identification, pedestrian detection, and obstacle resolution. The work deals with a review of the technical advances in neural networks concerning their capability for real-time data processing for accurate and reliable navigation. Further, this paper points out that the challenges to be faced during the implementation of these systems include requirements for data management, high-performance computing, and exploitation of cloud technologies for scalable solutions. The results indicate that machine learningbased detection strategies greatly enhance autonomous vehicle performance and safety, while emphasising persistent issues concerning security and legal frameworks. This paper highlights the significance of ongoing technological advancements in machine learning and its influence on the development of autonomous driving.

Spatiotemporal energy regulation strategy for enhancing SNR and spatial resolution in the damage detection with SH0 waves

The fundamental shear horizontal (SH0) wave, which can be generated by electromagnetic acoustic transducers (EMATs), is widely used in the structural health monitoring fields owing to its non-dispersive nature and the ability to detect over long distances. However, current SH0 wave methods hardly achieve the excellent signal-to-noise ratio (SNR) of the echo signals and satisfactory spatial resolution to defects due to the co-restriction between them. To address these issues, a spatiotemporal energy regulation strategy (STERS) is proposed in this paper to optimize energy distribution in the temporal and spatial dimensions. First, spatiotemporal pulse compression technology (STPCT) is proposed to improve both SNR and spatial range resolution for defect detection. Second, a staggered dual-exciter employing two sets of excitation signals is designed to improve the spatial azimuth resolution. Besides, a double sidelobe suppression algorithm (DSSA) is proposed to suppress sidelobe issues arising from the application of STPCT, thereby further improving the performance of STPCT. Finally, multiple simulations and experiments are executed to demonstrate the advantages of the proposed damage detection system. Results show that our methods can achieve comprehensive improvement in SNR, spatial range resolution, spatial azimuth resolution, and sidelobe suppression ability.

Novel Spectrometer Designs for Laser-Driven Ion Acceleration

We propose novel spectrometer designs that aim to enhance the measured spectral range of ions on a finite-sized detector. In contrast to the traditional devices that use a uniform magnetic field, in which the deflection of particles increases inversely proportional to their momentum, in a gradient magnetic field, the deflection of particles will decrease due to the reduction of the magnetic field along their propagation. In this way, low-energy ions can reach the detector because they are deflected less, compared to the uniform field case. By utilizing a gradient magnetic field, the non-linear dispersion of ions in a homogeneous magnetic field approaches nearly linear dispersion behavior. Nonetheless, the dispersion of low-energy ions, using a dipole field, remains unnecessarily high. In this article, we discuss the employed methodology and present simulation results of the spectrometer with an extended ion spectral range, focusing on the minimum detectable energy (energy dynamic range) and energy resolution.