Typical Accuracy Research Articles

A comprehensive study of ultrasonic detection and damage quantification of barely visible impact damages in a carbon fiber reinforced polymer composite material

AbstractThis work investigates detection and evaluation of barely visible impact damage (BVID) on a carbon fiber reinforced polymer composite using non‐destructive evaluation. Specifically, this paper presents a novel method to analyze full waveform from ultrasonic data captured from a new field portable inspection station. Forty‐eight samples are impacted between 8 and 16 J representing a spectrum of surface damage below the visual threshold to barely visible surface damage. The samples are conditioned at cold and dry (5°C and 10%RH) to hot and wet (50°C and 90%RH) environmental conditions prior to inspection. Data collection for ultrasonic inspection is performed on a novel portable inspection system outside of an immersion tank, and the captured full waveform data is analyzed. The waveforms are analyzed using a new automated analysis approach presented in the current manuscript, and the effective diameter of the subsurface damage as a function of depth is extracted from the data set. The extracted three‐dimensional damage zone from the analysis of the ultrasound data shows damage increasing from the surface that is at or below the visual inspection threshold to a circular like damage zone with an effective diameter subsurface that is more than 20 mm. These damage zones are compared to the analyzed μCT data sets, and the average error is nominally 1 mm in characterizing the effective diameter at any depth. There is little correlation between the error and the impact energy or the environmental conditions studied, with the error ranging from 4% to 6% over the samples investigated.Highlights Out of immersion tank, field‐portable ultrasound inspection station, to detect BVID. Automated procedure to characterize three dimensionally the damage from a barely visible impact damage event. Sensitivity to environmental conditioning is investigated for its impact on inspections. Results validated with x‐ray CT with a typical accuracy of 1.32 mm.

Chiral-odd GPDs in the bag model

A study of chiral-odd generalized parton distributions (GPDs) of the nucleon is presented in the bag model demonstrating that in this model all four chiral-odd GPDs are nonzero contrary to other claims in literature. The bag model results for the GPDs HTq(x,ξ,t), ETq(x,ξ,t), H˜Tq(x,ξ,t) agree with other models within a typical quark model accuracy. We present one of the few quark model calculations where polynomiality is satisfied and the sum rule ∫dxE˜Tq(x,ξ,t)=0 holds. We confront our results with predictions from the large-Nc limit, and with lattice QCD calculations. We conclude that the bag model successfully catches the main features of chiral-odd GPDs. Published by the American Physical Society 2024

Quantification of Crystal Chemistry of Fe‐Mg Carbonates by Raman Microspectroscopy and Near‐Infrared Remote Sensing

AbstractOn Earth, carbonate minerals are widely used as recorders of the geological environments in which they formed. Here, we present a method designed to retrieve the crystal chemistry of Fe‐Mg carbonate minerals using infrared remote sensing or Raman spectroscopy. We analyzed a suite of well‐characterized Fe‐Mg carbonate minerals for which Raman spectra were obtained in two different laboratories, and IR spectra were measured in reflectance and transmission from the visible range to 25‐μm. We built calibration lines for the dependence of fundamental and harmonic vibrational modes position to the Mg# (defined as Mg# = 100 × Mg/(Mg + Fe + Ca + Mn)). These calibrations should enable retrieval of Mg# based on spectroscopic observations with a typical accuracy of 10. We discuss the framework of applicability of these calibrations and apply them to a typical CRISM spectrum of carbonates from the Nilli Fossae region of Mars.

Modeling and Analysis of Monkeypox Outbreak Using a New Time Series Ensemble Technique

The coronavirus pandemic has raised concerns about the emergence of other viral infections, such as monkeypox, which has become a significant hazard to public health. Thus, this work proposes a novel time series ensemble technique for analyzing and forecasting the spread of monkeypox in the four highly infected countries with the monkeypox virus. This approach involved processing the first cumulative confirmed case time series to address variance stabilization, normalization, stationarity, and a nonlinear secular trend component. After that, five single time series models and three proposed ensemble models are used to estimate the filtered confirmed case time series. The accuracy of the models is evaluated using typical accuracy mean errors, graphical evaluation, and an equal forecasting accuracy statistical test. Based on the results, it is found that the proposed time series ensemble forecasting approach is an efficient and accurate way to forecast the cumulative confirmed cases for the top four countries in the world and the entire world. Using the best ensemble model, a forecast is made for the next 28 days (four weeks), which will help understand the spread of the disease and the associated risks. This information can prevent further spread and enable timely and effective treatment. Furthermore, the developed novel time series ensemble approach can be used to forecast other diseases in the future.

Sequence dependence of critical properties for two-letter chains.

Histogram-reweighting grand canonical Monte Carlo simulations are used to obtain the critical properties of lattice chains composed of solvophilic and solvophobic monomers. The model is a modification of one proposed by Larson et al. [J. Chem. Phys. 83, 2411 (1985)], lowering the "contrast" between beads of different types to prevent aggregation into finite-size micelles that would mask true phase separation between bulk high- and low-density phases. Oligomeric chains of lengths between 5 and 24 beads are studied. Mixed-field finite-size scaling methods are used to obtain the critical properties with typical relative accuracies of better than 10-4 for the critical temperature and 10-3 for the critical volume fraction. Diblock chains are found to have lower critical temperatures and volume fractions relative to the corresponding homopolymers. The addition of solvophilic blocks of increasing length to a fixed-length solvophobic segment results in a decrease of both the critical temperature and the critical volume fraction, with an eventual slow asymptotic approach to the long-chain limiting behavior. Moving a single solvophobic or solvophilic bead along a chain leads to a minimum or maximum in the critical temperature, with no change in the critical volume fraction. Chains of identical length and composition have a significant spread in their critical properties, depending on their precise sequence. The present study has implications for understanding biomolecular phase separation and for developing design rules for synthetic polymers with specific phase separation properties. It also provides data potentially useful for the further development of theoretical models for polymer and surfactant phase behavior.

The far infrared absorption spectrum of D216O, D217O, and D218O: Experimental line positions, empirical energy levels and recommended line lists

The far infrared absorption spectra of D216O, D217O, and D218O are analyzed with improved accuracy and sensitivity in the 50–720 cm−1 range corresponding to the rotational band. Four room-temperature absorption spectra of highly deuterated water vapor were recorded at the SOLEIL synchrotron by high-resolution Fourier transform spectroscopy. Line centers are reported with a typical accuracy of 5 × 10−5 cm−1 for well isolated lines. The combined line list of about 9700 water lines was assigned to about 10 400 transitions of the nine stable water isotopologues (H2XO, HDXO, D2XO, with X = 16, 17, and 18). A total of 2885 transitions of eight bands involving the first five vibrational states were assigned to D216O. Among them, 2057 are newly reported. The obtained set of transition frequencies was merged with literature data to generate a new set of empirical energy levels for the first five vibrational states of D216O. A total of 1089 transitions of the (000)–(000) and (010)–(010) bands were measured for D217O. They were merged with literature sources to derive 724 empirical term values of seven vibrational states, up to 8088 cm−1. 348 D217O levels are newly determined. A set of 1150 transitions belonging to the (000)–(000) and (010)–(010) bands was measured for D218O. 3451 empirical energies of rotation–vibration levels up to 9222 cm−1 were retrieved using our observations and literature sources. The extension and accuracy of the derived empirical energy levels allow us to recommend new line lists with empirically corrected line positions for D216O, D217O, and D218O.

Combined Data-Driven and Model-Driven Location of Lightning Strikes: Application to Meshed HVDC Grids

This paper addresses the low-delay location of faults due to lightning strikes using single-ended measurements in HVDC grids. A combined data-driven and model-driven approach is used to estimate the fault location iteratively. No prior knowledge of the voltage evolution at the fault location is required. Once the first wavefront due to a fault is detected at some observation location of the HVDC grid, the measurements are fed to a model of the propagation of transient waves along the lines. The model is parameterized by the estimated fault location. As a result, a model of the waveform samples starting from the second wavefront is obtained. The measured and modeled waveform samples are then compared to update the estimate of the fault location. The performance of the proposed approach is evaluated via simulations, including field measurements of lightning currents. Typical location accuracy of 300 m is obtained by considering observations performed at 1 MHz over an observation time interval of less than 1.5 ms.

Optimizing Sensor Localization and Cluster Performance in Wireless Sensor Networks through Internet of Thing (IoT) and Boosted Weight Centroid Algorithm

Localization is an extremely important component of applications that make use of wireless sensor networks. It has a substantial impact on academics as well as real-time sensor deployment applications in the aim of lowering the amount of energy that is used while simultaneously locating unknown nodes. The process of obtaining the coordinates along an axis that represent the locations of the sensor nodes is referred to as localization. The accuracy of locating the positions of the nodes varies depending on the environmental conditions, the type of nodes, the type of application, and the type of localization methods used. A standard localization method known as distance vector hop (DV-hop) localization will be able to determine the positions of unknown nodes with typical accuracy with the assistance of beacon nodes based on Internet of things. The DV-hop and improved weighted centroid localization algorithms, in addition to the suggested boosted weight centroid-based localization approach, are both addressed in this article. The suggested boosted weight centroid localization technique is utilized to find nodes in the remote area of the WSN while conserving energy. This is accomplished with the assistance of measurements involving both the nodes and the centroid. The modified weight metric is utilized in the process of carrying out the task of localisation of an unknown node. The performance of BWCLA is evaluated based on a number of different metrics, including accuracy in localization, average localization error, total packets utilized, and energy usage.

Integrated Leaf Disease Recognition Across Diverse Crops through Transfer Learning

Global food security is seriously threatened by plant diseases and can cause severe economic losses to farmers. Automated detection of plant diseases using computer vision and machine learning techniques has become a popular research area due to its potential to provide faster and more accurate results than traditional methods. In this research, we propose a plant disease detection model based on transfer learning using the MobileNetV2. We evaluate the suggested method on a dataset consisting of 38 various kinds of diseases across 14 different plants. Our experimental findings indicate that the proposed method has a typical accuracy of 91.98% and outperforms additional cutting-edge CNN models for plant disease detection. The experimental findings support the suggested approach's validity and show that it effectively detects plant diseases. We also have put forth the evaluation metrics to investigate the model. The suggested method has potential applications in real-world scenarios and can help farmers detect diseases in their crops at an early stage, allowing them to take timely action to minimize crop losses.

OP80 Diagnostic Molecular Sequencing Of DNA (Exomes And Genomes) Is Not Perfect: Implications For HTA

IntroductionThe recent release of powerful next-generation sequencing platforms, which can provide whole exome sequencing (WES) or whole genome sequencing (WGS) in quicker timelines and at reduced costs, has resulted in proposals for these diagnostic testing methods to be routinely integrated into clinical practice in multiple settings. However, the complexities of these diagnostic approaches, and the minimal comparative evidence available on them, creates difficulties in the evaluation of their diagnostic performance. Novel approaches need to be developed to improve the health technology assessment (HTA) of WES and WGS.MethodsSeveral HTAs on genetic testing and the use of WES or WGS in fetal medicine were reviewed. Information on factors associated with this diagnostic modality that affect typical test accuracy assessment (e.g., sensitivity and specificity) was extracted. The multiple steps required for completing a WES or WGS test, and the potential for the introduction of errors (type I or type II) at each of these steps, were mapped and examples provided. The clinical and economic implications associated with imperfect and uncertain test accuracy were described.ResultsLimited data on analytical and clinical validity were identified. WES and WGS are multistep processes and errors were found in sampling, molecular sequencing, bioinformatic filtering, and variant interpretation; therefore, the assumption that WES or WGS is 100 percent sensitive or specific is not reasonable. Although alternative evidence-based estimates are unlikely to be available, the inevitability of such errors, and their implications in terms of comparative effectiveness, safety, and cost effectiveness, should be described in HTAs.ConclusionsWhile unknown diagnostic accuracy remains an issue with WES and WGS testing, formal sensitivity analysis of test performance characteristics should be conducted as part of HTAs. A checklist has been developed to assist those involved in HTA and policy to understand the potential for inaccurate test results in clinical practice, and the risk-benefit implications of these diagnostic errors for patients.

Результаты астрометрических наблюдений АСЗ на пулковском 40-см телескопе в обсерватории Ассы-Тургень

We present the results of astrometric observations of two near-Earth asteroids (2005 XY7 and 2007 UM12) performed in September-November 2023 with the 40-cm Pulkovo telescope in the Assy-Turgen observatory. Stellar and asteroid pixel coordinates were calculated by varying the photo center position, background, and flux values for the PSF (point spread function) based on the analysis of the stellar images. The stars within the 4-arcmin asteroid-centered ring were not involved in the astrometric calibration. These stars were used for the asteroid systematic correction calculation. As a result, the internal accuracy of asteroid positions was better than 0.1 arcsec. The estimation of the mean position and the apparent rate components were performed for each set of CCD frames. Finally, the typical accuracy of the coordinates reached values of 0.024 – 0.088 arcsec. In addition, the numerical integration of the asteroid motion was made by varying the components of the state vector and A2-parameter (Yarkovsky acceleration). The unexpected and statistically insignificant A2 value for the 2007 UM12 has been found. It can be explained by the low quality of the data related to the first approach of this asteroid to the Earth and/or the tidal effects that changed the rotational state of the asteroid. The value A2 = (8.1 ± 6.4) · 10−14 a.u. per day2 on the significance boundary has been calculated for 2005 XY7 asteroid. This value does not contradict well-known data for the same size asteroids.

Automated bondline thickness quantification in adhesively joined composites and metals using ultrasound

AbstractThe use of adhesively bonded joints between composite panels, metal panels, or between composites and metals are used in the aerospace and automotive industries to avoid stress concentrations due to fasteners while reducing weight. Quantifying the bond thickness allows for confidence that loading is being properly transferred. This study presents a methodology to measure bondline thickness using the data obtained from an immersion quality ultrasound scan using an out‐of‐tank, field‐portable, utlrasonic testing (UT) scanner. Eighteen bonded coupons were fabricated using a paste‐type adhesive filling a range of gaps between substrates of 0.254 and 1.27 mm. Three adhesively bonded coupon types were investigated: carbon fiber laminates, fiber glass laminates, and aluminum plates. A semiautomated algorithm is presented to quantify bondline thickness from the ultrasound data for each coupon type, generating a spatially varying 3D point cloud of adhesive thickness. Bondline measurements obtained using ultrasound are then validated over two orthogonal planes against measurements taken from x‐ray computed tomography reconstructions. Results indicate a typical accuracy of 0.081 mm for bondline thickness quantification for all samples studied, with the results from the inspection of the composite coupons yielding an error of 0.078 mm, whereas the accuracy when scanning the aluminum coupons yielded an error of 0.086 mm.Highlights Field‐portable, inspection station is presented for full waveform ultrasonics. Mathematical procedure to characterize adhesive bondline thickness. Results are presented for a variety of material systems and adhesive thicknesses. Results are validated against x‐ray computed tomography with a typical accuracy of 0.081 mm.

Emulation of the cosmic dawn 21-cm power spectrum and classification of excess radio models using an artificial neural network

ABSTRACT The cosmic 21-cm line of hydrogen is expected to be measured in detail by the next generation of radio telescopes. The enormous data set from future 21-cm surveys will revolutionize our understanding of early cosmic times. We present a machine learning approach based on an artificial neural network that uses emulation in order to uncover the astrophysics in the epoch of reionization and cosmic dawn. Using a seven-parameter astrophysical model that covers a very wide range of possible 21-cm signals, over the redshift range 6 to 30 and wavenumber range 0.05 to $1 \ \rm {Mpc}^{-1}$ we emulate the 21-cm power spectrum with a typical accuracy of $10 - 20~{{\ \rm per\ cent}}$. As a realistic example, we train an emulator using the power spectrum with an optimistic noise model of the square kilometre array (SKA). Fitting to mock SKA data results in a typical measurement accuracy of 2.8 per cent in the optical depth to the cosmic microwave background, 34 per cent in the star-formation efficiency of galactic haloes, and a factor of 9.6 in the X-ray efficiency of galactic haloes. Also, with our modelling we reconstruct the true 21-cm power spectrum from the mock SKA data with a typical accuracy of $15 - 30~{{\ \rm per\ cent}}$. In addition to standard astrophysical models, we consider two exotic possibilities of strong excess radio backgrounds at high redshifts. We use a neural network to identify the type of radio background present in the 21-cm power spectrum, with an accuracy of 87 per cent for mock SKA data.

Comprehensive evaluation and comparison of ten precipitation products in terms of accuracy and stability over a typical mountain basin, Southwest China

Reliable precipitation information is important for a multitude of scientific and operational applications. Open-access gridded precipitation products (OGPPs) are important information sources owing to their spatiotemporal continuity and large-scale coverage. However, few studies have comprehensively compared the accuracies and stabilities of various OGPPs, particularly in mountainous basins. The key methodological challenges are how to quantitatively evaluate stability and how to rationally assemble accuracy and stability characteristics to determine the best product. To address these requirements and challenges, we propose a three-stage framework methodology based on typical statistical accuracy metrics, sample entropy, and an innovative decision support index. Subsequently, the framework was applied to comprehensively compare ten OGPPs. The comparison was conducted at the basin and point scales over the Chengbi River Basin (Southwest China), which is equipped with mountainous topography and 12 independent precipitation gauges. The results show that all OGPPs had high accuracy, but their performance was unstable. Meanwhile, all products tended to have lower accuracies but similar stabilities at higher altitudes. In addition, all OGPPs had better accuracy at the basin scale than at the point scale; however, there was no significant scale phenomenon in terms of stability. Multi-source fusion-type products (i.e., multi-source weighted-ensemble precipitation and China meteorological forcing dataset) tended to be more stable than other products while offering outstanding accuracy. Furthermore, regarding the assembly accuracy and stability characteristics, the multi-source weighted-ensemble precipitation and climate prediction center morphing method products exhibited the best comprehensive performance at the point and basin scales, respectively. This study provides an efficient methodology for OGPP comparisons and valuable guidance for precipitation product development and application.

Circuit-Depth Reduction of Unitary-Coupled-Cluster Ansatz by Energy Sorting.

Quantum computation represents a revolutionary approach to solving problems in quantum chemistry. However, due to the limited quantum resources in the current noisy intermediate-scale quantum (NISQ) devices, quantum algorithms for large chemical systems remain a major task. In this work, we demonstrate that the circuit depth of the unitary coupled cluster (UCC) and UCC-based ansatzes in the algorithm of the variational quantum eigensolver can be significantly reduced by an energy-sorting strategy. Specifically, subsets of excitation operators are first prescreened from the operator pool according to its contribution to the total energy. The quantum circuit ansatz is then iteratively constructed until convergence of the final energy to a typical accuracy. For demonstration, this method has been successfully applied to molecular and periodic systems. Particularly, a reduction of 50%-98% in the number of operators is observed while retaining the accuracy of the original UCCSD operator pools. This method can be straightforwardly extended to general parametric variational ansatzes.

A differentiable model of the evolution of dark matter halo concentration

ABSTRACT We introduce a new model of the evolution of the concentration of dark matter haloes, c(t). For individual haloes, our model approximates c(t) as a power law with a time-dependent index, such that at early times, concentration has a nearly constant value of c ≈ 3–4, and as cosmic time progresses, c(t) smoothly increases. Using large samples of halo merger trees taken from the Bolshoi–Planck and MultiDark Planck 2 cosmological simulations, we demonstrate that our three-parameter model can approximate the evolution of the concentration of individual haloes with a typical accuracy of 0.1 dex for $t\gtrsim 2\, {\rm Gyr}$ for all Bolshoi–Planck and MultiDark Planck 2 haloes of present-day peak mass $M_{0}\gtrsim 10^{11.5}\, {\rm M}_{\odot }$. We additionally present a new model of the evolution of the concentration of halo populations, which we show faithfully reproduces both average concentration growth and the diversity of smooth trajectories of c(t), including capturing correlations with halo mass and halo assembly history. Our publicly available source code, diffprof, can be used to generate Monte Carlo realizations of the concentration histories of cosmologically representative halo populations. diffprof is differentiable due to its implementation in the jax autodiff library, which facilitates the incorporation of our model into existing analytical halo model frameworks.

A free-surface particle regularization scheme based on numerical integration for particle methods

Particle shifting model plays a significant role in regularizing particle distribution in high-order accuracy Lagrangian particles methods. However, due to the incomplete neighbouring support of surface particles, the treatment of particle shifting models applied to free-surface particles still deserves attention from researchers. A new free-surface particle regularization scheme based on numerical integration (NIPS) for particle methods is proposed in this study. Specifically, high-resolution surrounding meshes are seeded outside the free surfaces to supplement the incomplete neighbouring support. Then, the contribution of the void region outside the free surface to the particle shifting vector is numerically integrated based on the surrounding meshes. The appropriate resolution and the screen scheme for constructing the surrounding meshes are optimized in this study. This scheme is easy to implement because the particle number density is only employed to screen the surrounding meshes. A typical high-order accuracy particle method, the LSMPS method is taken to evaluate the proposed scheme in this study. Numerical examples demonstrated that the proposed regularization method can keep uniform distribution of surface particles, thus the instability due to heterogeneous surface particles distribution can be effectively avoided.

A Theoretical Framework for the Analysis of Physical Unclonable Function Interfaces and Its Relation to the Random Oracle Model

Analysis of advanced physical unclonable function (PUF) applications and protocols relies on assuming that a PUF behaves like a random oracle; that is, upon receiving a challenge, a uniform random response with replacement is selected, measurement noise is added, and the resulting response is returned. In order to justify such an assumption, we need to rely on digital interface computation that to some extent remains confidential—otherwise, information about PUF challenge–response pairs leak with which the adversary can train a prediction model for the PUF. We introduce a theoretical framework that allows the adversary to have a prediction model (with a typical accuracy of 75% for predicting response bits for state-of-the-art silicon PUF designs). We do not require any confidential digital computing or digital secrets, while we can still prove rigorous statements about the bit security of a system that interfaces with the PUF. In particular, we prove the bit security of a PUF-based random oracle construction; this merges the PUF framework with fuzzy extractors.

THz computed tomography for non-destructive testing

This work describes a complete THz computed tomography imaging system. Starting from a physical imaging model based on geometrical optics, an image reconstruction algorithm is derived. This algorithm uses the raw time-domain measurement signals acquired from THz time-domain spectroscopy measurements of the sample in order to calculate the sample cross-section. In particular, the phase of the transmitted THz pulse is evaluated for image reconstruction. The results show a significant improvement compared to the reconstruction based solely on the absorption. If preliminary knowledge about the sample geometry is available, refraction effects occurring on the sample interfaces can be considered in order to obtain a more accurate measurement result. This is especially beneficial in industrial non-destructive testing, where a sample is typically tested for deviations from a predefined specification or geometrical shape. Typical accuracies around 150 µm are demonstrated using 3d printed benchmark samples.

Photometric metallicity for 694 233 Galactic giant stars from Gaia DR3 synthetic Strömgren photometry

We used two previous calibrations and the standardised synthetic photometry in the v, b, and y Strömgren passbands from Gaia DR3 BP/RP spectra to obtain photometric metallicities for a selected sample of 694 233 old Galactic giant stars having |b|> 20.0° and parallax uncertainties lower than 10%. The zero point of both sets of photometric metallicities has been shifted to ensure an optimal match with the spectroscopic [Fe/H] values for 44 785 stars in common with APOGEE DR17, focusing on the metallicity range where they provide the highest accuracy. The metallicities derived in this way from one calibration display a typical accuracy of ≲0.1 dex and 1σ precision ≲0.2 dex in the range −2.2 ≲ [Fe/H] ≲ −0.4, while they show a systematic trend with [Fe/H] at higher metallicity, beyond the applicability range of the relation. Those derived from the other calibration display, in general, reduced precision, and lower accuracy in the metal-poor regime, but have a median accuracy < 0.05 dex for [Fe/H] ≥ − 0.8. These results are confirmed and, consequently, the metallicities are validated, by comparison with large sets of spectroscopic metallicities from various surveys. The newly obtained metallicities are used to derive metallicity distributions for several previously identified substructures in the Galactic halo with an unprecedented number of stars. The catalogue including the two sets of metallicities and the associated uncertainties is made publicly available.