bluuebunny/crossref_metadata_2025_split huggingface dataset:
Deep learning‐based methods for detecting defects in cast iron parts and surfaces
Authors: Wang Pengyu , Jing Peng 
Published: September 2023

AbstractThe large size tolerance and positional differences of burrs in cast iron blanks make it easy for traditional teaching polishing paths to cause overcutting or undercutting. Rapid and accurate identification of burrs and real‐time correction of polishing trajectories are key technical issues for achieving high‐precision polishing. Here, a deep learning‐based method for defect detection in cast iron parts and surfaces is proposed. Firstly, a self‐made dataset of cast iron parts and surface defects is created and annotated, and a variety of data augmentation methods are used to expand the number of samples in the original dataset, alleviating the problem of small sample size. Then, the coordinate attention mechanism is introduced into the backbone network to allocate more attention to the defect target. Finally, the bidirectional weighted feature pyramid network (BiFPN) is used in the feature fusion network to replace the original path aggregation network, improving the model's ability to fuse features of different sizes. Experimental results show that compared with the original model, the mean average precision (mAP) is increased by 3.1%, and the average precision (AP) in defect classification is increased by 7.6%, with an FPS of 112, achieving accurate and efficient real‐time detection of cast iron parts and surface defects.
Robust dynamic and algebraic state estimation for microgrids: A generalized approach
Authors: Pourkeivani Iraj , Abedi Mehrdad , Kouhsari Shahram Montaser , Yaqoubi Kazem , Fahimi Ali 
Published: September 2023

AbstractNetwork control, optimization, and security analysis are facilitated by accurate microgrid state estimation. By utilizing phasor measurement units (PMUs), a combined robust centralized dynamic algebraic approach is proposed in this paper for estimating algebraic states (voltage phasors) as well as dynamic states (associated with synchronous generators and wind turbines). Assuming that a load is placed on each bus, an innovative PMU placement method is also presented to provide measurements for all dynamic and algebraic state variables. As a robust link between algebraic state estimation and dynamic state estimation, the output results of the least absolute value (LAV) estimator, which is robust against bad data, are fed to dynamic state estimators as pseudo measurements. Next, to address the nonlinearity of synchronous generator and wind turbine models, an unscented Kalman filter (UKF) is applied to estimate dynamic states precisely. The numerical tests on a microgrid test system show that the suggested approach is suitable for both algebraic and dynamic state estimation. Synchronous generators and wind turbines are modeled using nonlinear models of the 9th and third orders, respectively, and static loads are modeled as voltage‐frequency dependent ones.
Joint antenna selection and beamforming for frequency diverse multiple‐input multiple‐output radar in mainlobe spectrum interferences and signal‐dependent interferences coexistence scenarios
Authors: Shao Xiaolang , Hu Taiyang , Zhang Jinyu , Xiao Zelong 
Published: September 2023

AbstractDue to the controllable degrees of freedom of frequency diverse array in the distance dimension, the frequency diverse multiple‐input multiple‐output (FDA‐MIMO) radar can easily deal with mainlobe interference, which is often difficult to solve in traditional phased arrays. Nevertheless, the performance of FDA‐MIMO radar will suffer from degradation in the scenario where spectrum interferences and signal‐dependent interferences coexist. In order to solve this problem, a novel FDA‐MIMO radar framework via antenna switching is proposed. Based on this framework, an effective method for jointly optimising antenna selection and beamforming against spectrum interferences and signal‐dependent interferences is developed. The resulting optimization problem is nonconvex and NP‐hard owing to the integer constraints caused by antenna selection. By relaxing the integer constraints, the original problem can be transformed into a convex optimization form and an iterative reweighting strategy is used to force the obtained solution to satisfy the integer constraints. Simulation examples show that the proposed algorithm has better performance in output signal‐to‐interference‐plus‐noise ratio (SINR) and beampattern radiation performance than the existing competitive methods.
Investigating the effects of uniaxial pressure on the preparation of MgTiO3–CaTiO3 ceramic capacitors for MRI systems
Authors: Jebri Zaineb , Taleb Ali Mahfoudh , Bord Majek Isabelle 
Published: September 2023

AbstractToday's healthcare system relies on magnetic resonance imaging (MRI) for early diagnosis and treatment planning. For open MRI systems to achieve resolutions of about a hundred microns, a high voltage is required, as well as a specialized power supply. Negative–positive–zero (NP0) ceramic is selected for the fabrication of adjustable capacitors. Specifically, it stands for which is a classification based on the temperature coefficient of capacitance (TCC) of the ceramic material used in the capacitor. NP0 capacitors have a TCC of 0 ±30 ppm/°C, which means that their capacitance value does not change significantly with temperature and frequency. They are known for their stability and low losses, making them ideal for applications that require high accuracy and reliability, such as timing circuits for radio frequency (RF) applications. Here, MgTiO3–CaTiO3 ceramic is used to make an adjustable capacitor with desired properties for MRI systems. To enhance the dielectric properties of MgTiO3 ceramics, CaTiO3 was added in varying concentrations. After pressing and sintering, the resulting samples were tested using a vector network analyzer in the frequency range of 10–130 MHz. The adjustable capacitor fabricated using high co‐fired NP0 ceramic may have been used for MRI applications such as tuning circuits and matching networks, where precise capacitance values and low loss are critical. MRI systems with resonance frequencies of 128 MHz require trimmers with ceramic cores (VBreakdown = 3 kV @ 128 MHz, Cmin = 3 pF, CMax = 30 pF, and Cvariation step = 1.5 pF).
Bayesian radio interferometric imaging with direction-dependent calibration
Authors: Roth Jakob , Arras Philipp , Reinecke Martin , Perley Richard A. , Westermann Rüdiger , Enßlin Torsten A. 
Published: September 2023

Context.Radio interferometers measure frequency components of the sky brightness, modulated by the gains of the individual radio antennas. Due to atmospheric turbulence and variations in the operational conditions of the antennas, these gains fluctuate. Thereby the gains do not only depend on time, but also on the spatial direction on the sky. To recover high-quality radio maps, an accurate reconstruction of the direction and time-dependent individual antenna gains is required.Aims.This paper aims to improve the reconstruction of radio images, by introducing a novel joint imaging and calibration algorithm including direction-dependent antenna gains.Methods.Building on the resolve framework, we designed a Bayesian imaging and calibration algorithm utilizing the image domain gridding method for numerically efficient application of direction-dependent antenna gains. Furthermore, by approximating the posterior probability distribution with variational inference, our algorithm can provide reliable uncertainty maps.Results.We demonstrate the ability of the algorithm to recover high resolution high dynamic range radio maps from VLA data of the radio galaxy Cygnus A. We compare the quality of the recovered images with previous work relying on classically calibrated data. Furthermore, we compare the results with a compressed sensing algorithm also incorporating direction-dependent gains.Conclusions.Including direction-dependent effects in the calibration model significantly improves the dynamic range of the reconstructed images compared to reconstructions from classically calibrated data. Compared to the compressed sensing reconstruction, the resulting sky images have a higher resolution and show fewer artifacts. For utilizing the full potential of radio interferometric data, it is essential to consider the direction dependence of the antenna gains.
Stability and instability of strange dwarfs
Authors: Di Clemente Francesco , Drago Alessandro , Char Prasanta , Pagliara Giuseppe 
Published: September 2023

Aims. More than 20 years ago, the existence of stable white dwarfs with a core of strange quark matter was proposed. More recently, via the study of radial modes, it has been concluded instead that such objects are unstable. We aim to clarify this issue.
Methods. We investigated the stability of these objects by looking at their radial oscillations while incorporating boundary conditions at the quark–hadron interface, which correspond to either a rapid or a slow conversion of hadrons into quarks.
Results. Our analysis shows that objects of this type are stable if the star is not strongly perturbed and ordinary matter cannot transform into strange quark matter because of the Coulomb barrier separating the two components. On the other hand, ordinary matter can be transformed into strange quark matter if the star undergoes a violent process, as in the preliminary stages of a type Ia supernova, and this causes the system to become unstable and collapse into a strange quark star. In this way, the accretion-induced collapse of strange dwarfs can be facilitated, and kilometre-sized objects with sub-solar masses can be produced.
Decagram-Scale Synthesis of N-{2-[4-(β-d-Glucopyranosyloxy)-2-methylphenyl]-1,1-dimethyl-2-oxoethyl}-3-methylthiophene-2-carboxamide (GPTC), a Metabolite of the Fungicide Isofetamid
Authors: Jang Hongjun , Kwak Soo Yeon , Baek Seung-Hoon , Lee Dongjoo , Kim Hyoungsu , Kim Young Hoon , Han Jae-hyuk , Park Youngjik 
Published: September 2023

AbstractA decagram-scale synthesis of N-{2-[4-(β-d-glucopyranosyloxy)-2-methylphenyl]-1,1-dimethyl-2-oxoethyl}-3-methylthiophene-2-carboxamide (GPTC), a metabolite of the fungicide isofetamid, has been achieved in a highly straightforward manner from the known compound 1-(4-hydroxy-2-methylphenyl)-2-methylpropan-1-one in eight steps with a 20% overall yield to provide a standard certified reference material for residue analysis in food.
Role of Computed Tomography and Magnetic Resonance Imaging in the Diagnosis of Coronary Artery Disease: Indications and Applications
Authors: Bhatia Mona , Kumar Parveen 
Published: September 2023

AbstractCoronary artery disease (CAD) is the leading cause of death worldwide. The diagnosis of CAD relies on the clinical history, electrocardiographic changes, and imaging findings. The available imaging methods include transthoracic echocardiography, computed tomography (CT), cardiac magnetic resonance (CMR) imaging, and invasive angiography. Over the last two decades, cardiac CT and CMR have emerged as promising noninvasive modalities in the assessment of patients with suspected and established CAD. Both the modalities have their own advantages and disadvantages which complement each other in comprehensive evaluation of CAD aiding in the diagnosis, guiding clinical decision-making, and improving risk stratification. In this article, we provide an overview of the techniques and clinical applications of cardiac CT and CMR imaging in the assessment of patients with CAD.
Fatty Liver Disease: Pathophysiology and Imaging Features
Authors: Maheshwari Sharad , Kumar Sachin , Nakshiwala Bharatbhai V. , Srivastav Ayush , Chavan Vinaya , Raut Abhijit , Maheshwari Anoushka 
Published: September 2023

AbstractFatty liver is a benign condition to start with and is characterized by excess triglyceride in the hepatocytes. However, in the long term, it can lead to increased oxidative stress & inflammation, with resultant steatohepatitis. This can subsequently progress to cirrhosis and eventually an increased risk of developing hepatocellular carcinoma (HCC). Liver biopsy is the gold standard for quantification of fat and assessing the degree of fibrosis, however, it is invasive and cannot be applied to a wider patient population. Conventional modalities like ultrasound offer a qualitative assessment of fat and are more subjective. Non-enhanced CT scan has been effectively used for fat quantification based on Hounsfield values. MRI & more recently MRI PDFF (proton density fat fraction) offers accurate diagnosis, quantification, and monitoring of fatty liver disease in a noninvasive manner. This acts like an Imaging biomarker. Newer techniques like USG Elastography & MR Elastography help in the detection of fibrosis. Steatohepatitis and early liver fibrosis are reversible and it is crucial to detect and quantify to guide disease management. The radiologist can play a vital role in quantifying fat, detecting fibrosis, and early signs of chronic liver disease.
Genetic Predisposition to Adverse Neurodevelopmental Outcome of Extremely Low Birth Weight Infants
Authors: Varner Michael W. , Thom Elizabeth A. , Cotten C. Michael , Hintz Susan R. , Page Grier P. , Rouse Dwight J. , Mercer Brian M. , Costantine Maged M. , Sorokin Yoram , Thorp John M. , Ramin Susan M. , Carpenter Marshall W. , O'Sullivan Mary J. , Peaceman Alan M. , Saade George R. , Dudley Donald J. , Caritis Steve N. ,   for the Eunice Kennedy Shriver National Institute of Child Health Human Development Maternal-Fetal Medicine Units Network Neonatal Research Network
Published: September 2023

Objective This study aimed to evaluate whether there are genetic variants associated with adverse neurodevelopmental outcomes in extremely low birth weight (ELBW) infants.
Study Design We conducted a candidate gene association study in two well-defined cohorts of ELBW infants (<1,000 g). One cohort was for discovery and the other for replication. The discovery case–control analysis utilized anonymized DNA samples and evaluated 1,614 single-nucleotide polymorphisms (SNPs) in 145 genes concentrated in inflammation, angiogenesis, brain development, and oxidation pathways. Cases were children who died by age one or who were diagnosed with cerebral palsy (CP) or neurodevelopmental delay (Bayley II mental developmental index [MDI] or psychomotor developmental index [PDI] < 70) by 18 to 22 months. Controls were survivors with normal neurodevelopment. We assessed significant epidemiological variables and SNPs associated with the combined outcome of CP or death, CP, mental delay (MDI < 70) and motor delay (PDI < 70). Multivariable analyses adjusted for gestational age at birth, small for gestational age, sex, antenatal corticosteroids, multiple gestation, racial admixture, and multiple comparisons. SNPs associated with adverse neurodevelopmental outcomes with p < 0.01 were selected for validation in the replication cohort. Successful replication was defined as p < 0.05 in the replication cohort.
Results Of 1,013 infants analyzed (452 cases, 561 controls) in the discovery cohort, 917 were successfully genotyped for >90% of SNPs and passed quality metrics. After adjusting for covariates, 26 SNPs with p < 0.01 for one or more outcomes were selected for replication cohort validation, which included 362 infants (170 cases and 192 controls). A variant in SERPINE1, which encodes plasminogen activator inhibitor (PAI1), was associated with the combined outcome of CP or death in the discovery analysis (p = 4.1 × 10−4) and was significantly associated with CP or death in the replication cohort (adjusted odd ratio: 0.4; 95% confidence interval: 0.2–1.0; p = 0.039).
Conclusion A genetic variant in SERPINE1, involved in inflammation and coagulation, is associated with CP or death among ELBW infants.
Key Points
Car enthusiasm during the second and fourth waves of COVID-19 pandemic
Authors: Suchanek Michał , Szmelter-Jarosz Agnieszka 
Published: September 2023

AbstractThis paper investigates the car enthusiasm of Polish residents during the second and fourth waves of the pandemic. We try to answer if the car enthusiasm has changed between October 2020 and October 2021. Furthermore, we looked into the attitudes and beliefs of respondents about transport modes and their use, their perceived quality of life, and their opinions about sustainability and ecological lifestyle. We use a computer-assisted web interview (CAWI) survey in two rounds (October 2020 and October 2021). For data analysis, a structural equation modeling (SEM) model was proposed. We observe important changes in car enthusiasm between those two waves of the pandemic. Firstly, car enthusiasm was higher in 2021 than in 2020. Secondly, it was positively correlated with the ecological orientation of respondents. Thirdly, Y-generation respondents were less car enthusiastic. Fourthly, the influence of life quality on car enthusiasm was stronger in the fourth pandemic wave than during the second one.
Pressure-induced evolution of stoichiometries and electronic structures of host–guest Na–B compounds
Authors: Guo Zixuan , Li Xing , Bergara Aitor , Ding Shicong , Zhang Xiaohua , Yang Guochun 
Published: September 2023

Superionic and electride behaviors in materials, which induce a variety of exotic physical properties of ions and electrons, are of great importance both in fundamental research and for practical applications. However, their coexistence in hot alkali-metal borides has not been observed. In this work, we apply first-principles structure search calculations to identify eight Na–B compounds with host–guest structures, which exhibit a wide range of building blocks and interesting properties linked to the Na/B composition. Among the known borides, Na-rich Na9B stands out as the composition with the highest alkali-metal content, featuring vertex- and face-sharing BNa16 polyhedra. Notably, it exhibits electride characteristics and transforms into a superionic electride at 200 GPa and 2000 K, displaying unusual Na atomic diffusion behavior attributed to the modulation of the interstitial anion electrons. It demonstrates semiconductor behavior in the solid state, and metallic properties associated with Na 3p/3s states in the superionic and liquid regions. On the other hand, B-rich NaB7, consisting of a unique covalent B framework, is predicted to exhibit low-frequency phonon-mediated superconductivity with a Tc of 16.8 K at 55 GPa. Our work advances the understanding of the structures and properties of alkali-metal borides.
Sub-terahertz photoacoustic effect enabling broadband ultrasound generation for underwater communication
Authors: Hirata Tomoya , Inami Masahiko , Monnai Yasuaki 
Published: September 2023

Conventional wireless communication faces limitations in underwater environments due to the high electromagnetic wave attenuation. Ultrasound provides an alternative, enabling communication for underwater drones and intrabody communication for implantable devices. However, the limited bandwidth of resonance-based piezoelectric transducers remains a challenge. In addition, the significant acoustic impedance mismatch between water and air hinders cross-boundary communication and necessitates direct contact between the medium and the transducers. To overcome these challenges, we propose to use a sub-terahertz photoacoustic effect for the generation of broadband ultrasound in a non-contact manner. The photoacoustic effect generates acoustic signals in a medium through thermal expansion caused by optical irradiation. We demonstrate that the use of periodically modulated continuous-wave sub-terahertz waves around 0.1 THz enables broadband signal generation efficiently owing to their high attenuation in water. We characterize the frequency response of the generated acoustic signals and demonstrate a proof of concept for underwater communication.
Development of zero-noise extrapolated projective quantum algorithm for accurate evaluation of molecular energetics in noisy quantum devices
Authors: Halder Sonaldeep , Shrikhande Chinmay , Maitra Rahul 
Published: September 2023

The recently developed Projective Quantum Eigensolver (PQE) offers an elegant procedure to evaluate the ground state energies of molecular systems in quantum computers. However, the noise in available quantum hardware can result in significant errors in computed outcomes, limiting the realization of quantum advantage. Although PQE comes equipped with some degree of inherent noise resilience, any practical implementation with apposite accuracy would require additional routines to eliminate or mitigate the errors further. In this work, we propose a way to enhance the efficiency of PQE by developing an optimal framework for introducing Zero Noise Extrapolation (ZNE) in the nonlinear iterative procedure that outlines the PQE, leading to the formulation of ZNE-PQE. Moreover, we perform a detailed analysis of how various components involved in it affect the accuracy and efficiency of the reciprocated energy convergence trajectory. Additionally, we investigate the underlying mechanism that leads to the improvements observed in ZNE-PQE over conventional PQE by performing a comparative analysis of their residue norm landscape. This approach is expected to facilitate practical applications of quantum computing in fields related to molecular sciences, where it is essential to determine molecular energies accurately.
Accurate and efficient calculations of Hellmann–Feynman forces for quantum computation
Authors: Lai Juntao , Fan Yi , Fu Qiang , Li Zhenyu , Yang Jinlong 
Published: September 2023

First-order derivatives of energies with respect to atomic coordinates are widely computed and used in quantum chemistry simulations. The rapidly emerging technology of quantum computing offers a new paradigm for solving relevant quantum chemistry equations. In this work, we have achieved analytical calculations of atomic forces based on the Hellmann–Feynman theorem within the framework of the variational quantum eigensolver. The accuracy of the approach is demonstrated by calculating the atomic forces of H2, LiH, H2O, and NH3 molecules, which are in excellent agreement with values obtained from full configuration interaction calculations. In particular, for systems with degenerate molecular orbitals, the analytical approach has a significant accuracy advantage over finite-difference-based methods and will not involve additional computational effort on a quantum computer. The calculated forces are further used to optimize the geometries of NH3 and CH4 molecules and to perform ab initio molecular dynamics simulations for the umbrella inversion of NH3, demonstrating the feasibility of the approach in practical quantum chemistry simulations.
Novel design strategies of three-dimensional MXene structures and their applications in metal-ion hybrid capacitors
Authors: Li Lingfang , Zeng Bin , Xiang Chuang , Liu Wen 
Published: September 2023

MXene is a novel two-dimensional material that exhibits excellent competitive performance in energy storage and conversion applications due to its high electrical conductivity, good dispersibility, and abundant surface functional groups. However, the van der Waals interactions between MXene nanosheets tend to lead to stacking, which limits the number of active sites and ion dynamics. Constructing MXene materials into three-dimensional (3D) porous structures is an effective strategy to improve energy storage performance by increasing specific surface area and porosity, and decreasing ion transport distance. This review provides an overview of four novel design strategies for preparing three-dimensional MXene materials, including template-based, 3D printing, electrospinning, and gas-assisted methods, over the last 5 years (2019–2023), and explores the potential applications of 3D MXene structures in the new-type energy storage systems of metal-ion hybrid capacitors. Finally, the authors provide prospects for the future development of 3D MXene structures.