bluuebunny/crossref_metadata_2025_split huggingface dataset:
Strong nonlinear-polarization in ZnMgO epitaxial thin-films with Li incorporation
Authors: Meng Lei , Chai Hongyu , Gao Junjie , Lv Zunren , Yang Xiaoguang , Liu Wenkai , Zhai Tianrui , Yang Tao 
Published: April 2024

Abstract
The second-order nonlinear-polarization originated from the interaction between thin-film materials with second-order nonlinear susceptibility (χ
(2)) and high-power laser is essential for integrated optics and photonics. In this work, strong second-order nonlinear-polarization was found in a-axis oriented Zn1-x
Mg
x
O (ZnMgO) epitaxial thin-films with Li incorporation, which were deposited by radio-frequency magnetron sputtering. Mg incorporation (x > 0.3) causes a sharp fall in the matrix element χ
33 of χ
(2) tensor, although it widens optical bandgap (E
opt). In contrast, moderate Li incorporation significantly improves χ
33 and resistance to high-power laser pulses with a little influence on E
opt. In particular, a Zn0.67Mg0.33O:Li [Li/(Zn + Mg + Li) = 0.07] thin-film shows a |χ
33| of 36.1 pm V−1 under a peak power density (E
p) of 81.2 GW cm−2, a resistance to laser pulses with E
p of up to 124.9 GW cm−2, and an E
opt of 3.95 eV. Compared to that of ZnO, these parameters increase by 37.8%, 53.4%, and 18.6%, respectively. Specially, the Zn0.67Mg0.33O:Li shows higher radiation resistance than a Mg-doped LiNbO3 crystal with a comparable E
opt. First-principle calculations reveal the Li occupation at octahedral interstitial sites of wurtzite ZnO enhances radiation resistance by improving structural stability. X-ray photoelectron spectroscopy characterizations suggest moderate Li incorporation increases χ
33 via enhancing electronic polarization. These findings uncover the close relationship between the octahedra interstitial defects in wurtzite ZnMgO and its nonlinear-polarization behavior under the optical frequency electric field of high-power laser.
The mechanism of EP/SiC coating modulated DC flashover characteristics of epoxy composites in SF6/N2 mixtures
Authors: Li Zhen , Gao He , Mao Zirui , Zhu Bo , Sun Lei , Bi Xuefei , Zhu Yuanwei , Han Yongsen , Min Daomin , Liu Ji , Li Shengtao 
Published: April 2024

Abstract
Surface flashover is an inevitable insulation issue for basin-type insulators in gas-insulated switchgears/lines, which significantly challenges the reliability of the electrical power systems. Previous studies have indicated that polymer/semiconductor-filler composite coatings effectively improve the insulation properties; however, the influence mechanism of the coating materials on flashover has not been demonstrated from a molecular perspective. In this work, epoxy/silicon-carbide (EP/SiC) composites were coated onto an EP substrate. The energy-level structure, surface trap, surface charging, and DC flashover voltage in SF6/N2 were calculated and characterized, and the process by which the tailored molecular energy level influences surface charge transport and flashover characteristics was elucidated. The incorporating of SiC particles reduced the width of the bandgap and introduced shallow traps, which improved carrier mobility and surface conductivity. Quantitative analysis of charge transport indicated that the improved carrier mobility and reduced surface trap level accelerated the surface charge dissipation. This reduced the tangential electrical field distortion and surface charge density and further impeded gas ionization. When the SiC concentration was 15 wt%, the flashover performance improved by 20.88%. This study describes the mechanism by which the EP/SiC coating regulates the surface charge distribution to improve the surface flashover performance by establishing a relationship among the microscopic molecular energy-level structures, mesoscopic charge transport, and macroscopic discharge phenomena.
Enantioselectivity from inelastic electron tunnelling through a chiral sensor
Authors: Pandey Nidhi , Samal Ashutosh , Saha Archishman , Ganguly Swaroop 
Published: April 2024

Abstract
The vibration theory of olfaction, which explains it as the sensing of odorant molecules by their vibrational energies through inelastic electron tunnelling spectroscopy (IETS) has inspired olfactory sensor ideas. However, this theory has been presumed inadequate to explain the difference in smell between enantiomers (chiral molecules, which are mirror images of each other), since these have identical vibrational spectra. Going beyond phenomenological assumptions of enantioselective tunnelling, we show on the basis of ab initio modelling of real chiral molecules, that this drawback is indeed obviated for IETS-based olfactory sensors if they are chiral. Our treatment unifies IETS with chirality induced spin selectivity, which explains that charge polarization in chiral molecules by accompanied by spin polarization. First, we apply ab initio symmetry adapted perturbation theory to explain and illustrate enantioselective coupling of chiral odorant molecules and chiral olfactory sensors. This naturally leads to enantioselective coupling of the vibrational mode of an odorant to electron transport (electron-vibron coupling) in an IETS-based sensor when both odorant and sensor are chiral. Finally, we show, from phenomenological quantum transport calculations, that that in turn results in enantioselective IET spectra. Thus, we have demonstrated the feasibility of enantioselective sensing within a vibration framework. Our work also limns the possibility of quantum biomimetic electronic nose sensors that are enantioselective, a feature which could open up new sensing applications.
Grain boundary diffusion mechanism in Dy-diffused Nd–Fe–B sintered magnets
Authors: Dai Zhiming , Li Kai , Wang Zhenhua , Wang Tingting , Liu Wei , Zhang Zhidong 
Published: April 2024

Abstract
Grain boundary diffusion (GBD) is an effective method to enhance the thermal stability of Nd–Fe–B based permanent magnets. When developing a high-performance magnet, it is essential to carry out a study on its mechanisms, in order to reveal the distribution regulation of diffusion solutes and microstructural evolution. In the present work, the phase-field method is applied to investigate the thermodynamic features and the heavy rare-earth Dy migration in a Dy-diffused Nd–Fe–B magnet during the GBD process. In the simulation process, the grain phase transformation and volume diffusion were taken into consideration and the effects of the diffusion mode, initial diffusion source concentration, grain size, and grain boundary (GB) width were explored in a set of magnet models with various grain sizes. An optimized fitting function was introduced to evaluate the solute distribution in grain boundaries and the effective diffusion coefficient. It is shown that the diffusion mode and the GB width have significant impacts on the effective diffusion coefficient. The results provide a theoretical scheme concerning the quantitative evaluation of GBD efficiency based on thermodynamic analysis.
PMFSE: a video phase-based micro-vibration measurement algorithm for bridge cables in complex background
Authors: Zhang Gang , Yang Xuezhi , Zang Zongdi 
Published: April 2024

Abstract
The cable serves as the primary structural component in cable-stayed bridges, suspension bridges, and other cable-supported bridge designs. Accurate measurement of cable tension holds paramount importance for ensuring the overall safety and stability of bridge structures. Cable tension can be inferred from the vibration frequency, making precise measurement of cable vibration frequency of utmost practical significance. Presently, video-based methodologies, such as phase-based vibration extraction, present notable advantages in terms of speed, efficiency, and non-contact capabilities over conventional acceleration sensor approaches. However, these methods face challenges in accurately discerning the micro-vibration of cables in complex background interference. To address this problem, a phase magnification-based feature signal extraction (PMFSE) algorithm is proposed, which is suitable for detecting small vibration in complex background. The overall idea is to combine the small vibration enhancement method in spatial domain with the signal separation method in time domain. Specifically, in the spatial domain, edge phase information is amplified through phase amplitude weighting and phase enhancement techniques to mitigate non-edge noise. In time domain, cable signals are extracted based on distinguishing features between the cable signal and noise signal. The efficacy of PMFSE is evaluated in various outdoor experiments. Compared with the state-of-the-art methods, PMFSE exhibits substantial improvements on the cable micro-vibration frequency measurement in complex background.
A novel portable microchip electrophoresis system for rapid on-site detection of soil nutrient ions
Authors: Liu Yaping , Lu Zihao , He Wenhe , Wu Yanyan , Li Jingmin , Sun Cuimin 
Published: April 2024

Abstract
The conventional techniques for soil nutrient ion detection face challenges, including prolonged preparation periods and the necessity for distinct instruments tailored to each specific ion. To address these issues, we have engineered a cutting-edge soil nutrient ion detection apparatus: the Microchip Electrophoresis Soil Nutrient Ion Portable Detection System (ME-SNI-PDS). This system, leveraging microchip electrophoresis with a capacitively coupled contactless conductivity detector (ME-C4D), simplifies the detection process with user-friendly touchscreen controls. Our system is capable of simultaneous detection of key soil nutrient ions—ammonium (NH4
+), calcium (Ca2+), magnesium (Mg2+), potassium (K+), nitrate (NO3
−), and dihydrogen phosphate (H2PO4
−)—in a swift 180 s, facilitated by precise voltage regulation. We have refined the buffer solution, consisting of 20 mM 2-(N-morpholinyl)-ethanesulfonic acid and L-histidine, with the addition of 0.01 mM cetyltrimethylammonium bromide and 10 mM 18-crown-6, to ensure the complete resolution of soil nutrient ions. Following this, we established highly accurate peak height-to-concentration correlations for the six aforementioned ions, each with a coefficient of determination (R2) exceeding 0.99. The detection limits for these ions stand at a remarkably low concentration of 0.05 mM, translating to 0.9 mg l−1 for NH4
+, 2.0 mg l−1 for Ca2+, 1.2 mg l−1 for Mg2+, 1.96 mg l−1 for K+, 3.1 mg l−1 for NO3
−, and 4.85 mg l−1 for H2PO4
−. Subsequent soil leachate analysis via the ME-SNI-PDS has yielded ion content data that, upon comparison with results from continuous flow analyser (CFA) and inductively coupled plasma atomic emission spectrometry, confirm the system’s exceptional integration, compactness, portability, speed, and efficiency. The ME-SNI-PDS shows immense promise for application in precision agriculture and the prevention of surface soil pollution. It is poised to make a significant impact in the realm of crop fertilization and environmental stewardship.
An acoustic weighing method based on oscillation signal and feature enhanced network
Authors: Wang Yingwei , Li Xinbo , Jiang Liangxu , Sun Meiqi , Zhang Han , Sun Xiaodong 
Published: April 2024

Abstract
Acoustic weighing is a promising method for non-contact mass measurement of tiny objects as it avoids contamination and contact losses. However, due to the highly nonlinear nature of the acoustic field, some parameters of the mechanism model of acoustic weighing cannot be accurately simulated, thereby reducing the accuracy of acoustic weighing. To improve the accuracy of acoustic weighing, we propose an acoustic weighing method based on oscillating signals and feature enhancement network. Firstly, to drive the object oscillation and collect oscillation data, an acoustic levitation-based data acquisition system is constructed. Then, to break the limitations of the mechanism model, a feature enhancement network named CNN-BiLSTM-SE is proposed, which directly establishes the correlation between oscillating signals and actual mass. Finally, these data are used to train and test the proposed network model, validating the effectiveness of the model. Experimental results show that the method achieves high accuracy in measuring object mass, following the actual measurements with remarkable consistency. In addition, our approach is also suitable for acoustic weighing of small and sensitive objects, opening up new perspective for the study and application of nonlinear acoustic systems.
Exact computation of projected sphere centres in cone beam x-ray projections
Authors: Burkhard Simon , Küng Alain 
Published: April 2024

Abstract
A method is presented for fitting the projected centres of spheres in cone beam x-ray imaging. By using a suitable coordinate system, the method allows direct and exact calculation of the sphere centre without fitting the projection shape with an ellipse and correcting from the ellipse centre to the sphere centre. Advantages in numerical implementation result from the number of unknown variables being reduced compared to ellipse fits. Additionally, the orientation of the detector relative to the x-ray source can be obtained from fitting the shapes of projections of multiple spheres without knowledge of the positions or dimensions of the spheres. The accuracy of the method is compared to other techniques using simulated x-ray projections.
Characterisation of the interplay between microstructure and opto-electronic properties of Cu(In,Ga)S2 solar cells by using correlative CL-EBSD measurements
Authors: Hu Yucheng , Kusch Gunnar , Adeleye Damilola , Siebentritt Susanne , Oliver Rachel 
Published: April 2024

Abstract
Cathodoluminescence and electron backscatter diffraction have been applied to exactly the same grain boundaries (GBs) in a Cu(In,Ga)S2 solar absorber in order to investigate the influence of microstructure on the radiative recombination behaviour at the GBs. Two different types of GB with different microstructure were analysed in detail: random high angle grain boundaries (RHAGBs) and Σ3 GBs. We found that the radiative recombination at all RHAGBs was inhibited to some extent, whereas at Σ3 GBs three different observations were made: unchanged, hindered, or promoted radiative recombination. These distinct behaviours may be linked to atomic-scale grain boundary structural differences. The majority of GBs also exhibited a small spectral shift of about ±10 meV relative to the local grain interior (GI) and a few of them showed spectral shifts of up to ±40 meV. Red and blue shifts were observed with roughly equal frequency.
Vanishing viscosity limit for incompressible axisymmetric flow in the exterior of a cylinder
Authors: Liu Jitao 
Published: April 2024

Abstract
In this paper, we study the initial boundary value problem and vanishing viscosity limit for incompressible axisymmetric Navier–Stokes equations with swirls in the exterior of a cylinder under Navier-slip boundary condition. In the first part, we prove the existence of a unique global solution with the axisymmetric initial data

u

0

ν

∈

L

σ

2

(
Ω
)

and axisymmetric force

f

∈

L
2

(
[
0
,
T
]
;

L
2

(
Ω
)
)

. This result improves the initial regularity condition on the global well-posedness result obtained by K Abe and G Seregin (2020 Proc. R. Soc. Edinburgh A 150 1671–98) and extends their boundary condition. In the second part, we make the first attempt to investigate the inviscid limit of unforced viscous axisymmetric flows with swirls and prove that the viscous axisymmetric flows with swirls converge to inviscid axisymmetric flows without swirls under the condition

‖
r

u

0
θ

ν

‖

L
2

(
Ω
)

=

O

(

ν

)

. Some new uniform estimates, independent of the viscosity, are obtained here. The second result can be thought as a follow-up work to the previous work by K Abe (2020 J. Math. Pures Appl.
137 1–32), where the inviscid limit for the same equations without swirls in an infinite cylinder was studied.
b-MAR: bidirectional artifact representations learning framework for metal artifact reduction in dental CBCT
Authors: Song Yuyan , Yao Tianyi , Peng Shengwang , Zhu Manman , Meng Mingqiang , Ma Jianhua , Zeng Dong , Huang Jing , Bian Zhaoying , Wang Yongbo 
Published: April 2024

Abstract

Objective. Metal artifacts in computed tomography (CT) images hinder diagnosis and treatment significantly. Specifically, dental cone-beam computed tomography (Dental CBCT) images are seriously contaminated by metal artifacts due to the widespread use of low tube voltages and the presence of various high-attenuation materials in dental structures. Existing supervised metal artifact reduction (MAR) methods mainly learn the mapping of artifact-affected images to clean images, while ignoring the modeling of the metal artifact generation process. Therefore, we propose the bidirectional artifact representations learning framework to adaptively encode metal artifacts caused by various dental implants and model the generation and elimination of metal artifacts, thereby improving MAR performance. Approach. Specifically, we introduce an efficient artifact encoder to extract multi-scale representations of metal artifacts from artifact-affected images. These extracted metal artifact representations are then bidirectionally embedded into both the metal artifact generator and the metal artifact eliminator, which can simultaneously improve the performance of artifact removal and artifact generation. The artifact eliminator learns artifact removal in a supervised manner, while the artifact generator learns artifact generation in an adversarial manner. To further improve the performance of the bidirectional task networks, we propose artifact consistency loss to align the consistency of images generated by the eliminator and the generator with or without embedding artifact representations. Main results. To validate the effectiveness of our algorithm, experiments are conducted on simulated and clinical datasets containing various dental metal morphologies. Quantitative metrics are calculated to evaluate the results of the simulation tests, which demonstrate b-MAR improvements of >1.4131 dB in PSNR, >0.3473 HU decrements in RMSE, and >0.0025 promotion in structural similarity index measurement over the current state-of-the-art MAR methods. All results indicate that the proposed b-MAR method can remove artifacts caused by various metal morphologies and restore the structural integrity of dental tissues effectively. Significance. The proposed b-MAR method strengthens the joint learning of the artifact removal process and the artifact generation process by bidirectionally embedding artifact representations, thereby improving the model’s artifact removal performance. Compared with other comparison methods, b-MAR can robustly and effectively correct metal artifacts in dental CBCT images caused by different dental metals.
Evaluation of low-dose computed tomography reconstruction using spatial-radon domain total generalized variation regularization
Authors: Niu Shanzhou , Zhang Mengzhen , Qiu Yang , Li Shuo , Liang Lijing , Liu Qiegen , Niu Tianye , Wang Jing , Ma Jianhua 
Published: April 2024

Abstract
The x-ray radiation dose in computed tomography (CT) examination has been a major concern for patients. Lowing the tube current and exposure time in data acquisition is a straightforward and cost-effective strategy to reduce the x-ray radiation dose. However, this will inevitably increase the noise fluctuations in measured projection data, and the corresponding CT image quality will be severely degraded if noise suppression is not performed during image reconstruction. To reconstruct high-quality low-dose CT image, we present a spatial-radon domain total generalized variation (SRDTGV) regularization for statistical iterative reconstruction based on penalized weighted least-squares (PWLS) principle, which is called PWLS-SRDTGV for simplicity. The presented PWLS-SRDTGV model can simultaneously reconstruct high-quality CT image in space domain and its corresponding projection in radon domain. An efficient split Bregman algorithm was applied to minimize the cost function of the proposed reconstruction model. Qualitative and quantitative studies were performed to evaluate the effectiveness of the PWLS-SRDTGV image reconstruction algorithm using a digital 3D XCAT phantom and an anthropomorphic torso phantom. The experimental results demonstrate that PWLS-SRDTGV algorithm achieves notable gains in noise reduction, streak artifact suppression, and edge preservation compared with competing reconstruction approaches.
Numerical optimization of longitudinal collimator geometry for novel x-ray field
Authors: Insley Benjamin , Bartkoski Dirk , Balter Peter , Prajapati Surendra , Tailor Ramesh , Jaffray David , Salehpour Mohammad 
Published: April 2024

Abstract

Objective. A novel x-ray field produced by an ultrathin conical target is described in the literature. However, the optimal design for an associated collimator remains ambiguous. Current optimization methods using Monte Carlo calculations restrict the efficiency and robustness of the design process. A more generic optimization method that reduces parameter constraints while minimizing computational load is necessary. A numerical method for optimizing the longitudinal collimator hole geometry for a cylindrically-symmetrical x-ray tube is demonstrated and compared to Monte Carlo calculations. Approach. The x-ray phase space was modelled as a four-dimensional histogram differential in photon initial position, final position, and photon energy. The collimator was modeled as a stack of thin washers with varying inner radii. Simulated annealing was employed to optimize this set of inner radii according to various objective functions calculated on the photon flux at a specified plane. Main results. The analytical transport model used for optimization was validated against Monte Carlo calculations using Geant4 via its wrapper, TOPAS. Optimized collimators and the resulting photon flux profiles are presented for three focal spot sizes and five positions of the source. Optimizations were performed with multiple objective functions based on various weightings of precision, intensity, and field flatness metrics. Finally, a select set of these optimized collimators, plus a parallel-hole collimator for comparison, were modeled in TOPAS. The evolution of the radiation field profiles are presented for various positions of the source for each collimator. Significance. This novel optimization strategy proved consistent and robust across the range of x-ray tube settings regardless of the optimization starting point. Common collimator geometries were re-derived using this algorithm while simultaneously optimizing geometry-specific parameters. The advantages of this strategy over iterative Monte Carlo-based techniques, including computational efficiency, radiation source-specificity, and solution flexibility, make it a desirable optimization method for complex irradiation geometries.