bluuebunny/crossref_metadata_2025 huggingface dataset:
A broadband low-profile microwave absorber based on ferromagnetic material doped hybrid stereo metamaterial
Authors: Wei Xuyao , Wang Jiajia , Zhou Fangkun , Tan Ruiyang , Liu Jun , Chen Ping
Published: September 2023

This study introduces a ferromagnetic material-doped hybrid stereo metamaterial absorber (HSMA) that has been developed to overcome the limitations in broadband absorption of electromagnetic wave. This metamaterial combines a ferromagnetic block with a blind via in the center and a standing resistive trapezoidal patch together in a stereo meta-atom to enable a continuous and broad absorption band for 90% absorptivity from 2.3 GHz to 40 GHz, with a thickness only as 0.079 times the maximum working wavelength. The hybrid absorber also exhibits angular stability under oblique incidence and polarization insensitivity. Furthermore, a sample of proposed HSMA was fabricated and measured. The broadband absorption properties of such hybrid stereo metamaterial were validated by both simulated and experimental results. Our study provides a promising implementation approach for broadband and low-profile microwave absorbers.
Optical signal-based improvement of individual nanoparticle tracking analysis
Authors: Nguyen Minh-Chau , Bon Pierre
Published: September 2023

Nanoparticle tracking analysis (NTA) provides a simple method to determine individual nanoparticle (NP) size. However, because size quantification is based on the slowly converging statistical law of random events, its intrinsic error is large, especially in the case of limited event numbers, e.g. for weak scattering NPs. Here, we introduce an NTA improvement by analyzing each individual NP trajectory while taking into account the other trajectories with a weighting coefficient. The weighting coefficient is directly derived from the optical signature of each particle measured by quantitative phase microscopy. Simulations and experimental results demonstrate the improvement in NTA accuracy, not only for mono-disperse but also for poly-disperse particle solutions.
An effective method for fault diagnosis of rotating machinery under noisy environment
Authors: Xu Yonghui , Lu Xiang
Published: September 2023

Rotating machinery is widely utilized as mechanical equipment in the industrial field. However, due to the complex working conditions, the existing fault diagnosis methods have failed to address good results in practical applications. To improve the fault diagnosis performance of rotating machinery in a noisy environment, a new multi-scale convolution neural network (MSCN) based on a self-calibrating attention module is proposed. First, this thesis constructs a multi-scale convolution layer with a wide convolution kernel to form an efficient sampling structure at the filter level, which can filter out incoherent noise from the signals and extract rich features. Second, a multi-scale self-calibrating attention module is implemented with two identical self-calibrating convolutional networks to continuously focus on significant embeddings and adaptively combine information from different spatial dimensions. Third, the multi-dimensional characteristics are integrated by the feature cascade layer, and then the fault modes are identified though the classifier layer under noise. Finally, based on the Case Western Reserve University datasets and Paderborn University bearing datasets, the experimental results show that our proposed MSCN can significantly enhance the fault identification ability to rotate machinery in a noisy environment.
Constructing a noble-metal-free 0D/2D CdS/SnS2 heterojunction for efficient visible-light-driven photocatalytic pollutant degradation and hydrogen generation
Authors: Hu Hanmei , He Yunyun , Yu Hong , Li Dongcai , Sun Mei , Feng Yanyan , Zhang Chuanyue , Chen Haoran , Deng Chonghai
Published: September 2023

Semiconductor photocatalysis has attracted the attention of a wide audience for its outstanding capabilities in water purification and energy conversion. Herein, a noble-metal-free nanoheterojunction is created by planting zero-dimensional (0D) CdS nanograins, of 10–20 nm in size, on the surface of 2D SnS2 nanosheets (NSs) using an in situ chemical bathing deposition process, where SnS2 NSs have an average diameter of 400 nm and thicknesses of less than 20 nm. The possible formation mechanism of the CdS/SnS2 (CS/SS) heterogeneous nanostructure is elaborated upon. The catalytic activities over CS/SS nanocomposites for the photodegradation of organic dye and hydrogen evolution from photolysis water splitting are examined under visible light irradiation. The apparent rate constant (k) of the optimal CS/SS-3 composite in the decontamination of methylene blue (MB) is up to 3.34 and 1.87 times as high as that of pristine SnS2 and pure CdS counterparts, respectively. The optimized CS/SS-3 sample consistently achieves the highest photocatalytic hydrogen production rate, at 10.3 and 5.7 folds higher than that of solo SnS2 and CdS panels, respectively. The boosted photocatalytic capacities of CdS/SnS2 heterostructures are essentially attributed to the formation of the closely interfacial incorporation of CdS and SnS2 semiconductors, resulting in the effective charge transportation and spatial separation of the photoinduced electron–hole pairs. Furthermore, the traditional type-II charge transfer pathway is proposed based on the perfect band structure and the free radical experiment results.
Effect of fluorine doping on the NO2-sensing properties of MoS2nanoflowers
Authors: Huang Yixuan , Li Donglin , Chai Wenxiang , Jin Dingfeng , Jin Hongxiao
Published: September 2023

The somewhat slow recovery kinetics of NO2sensing at low temperatures are still challenging to overcome. To enhance the gas sensing property, fluorine is doped to MoS2nanoflowers by facile hydrothermal method. Extensive characterization data demonstrate that F was effectively incorporated into the MoS2nanoflowers, and that the microstructure of the MoS2nanoflowers did not change upon F doping. The two MoS2doped with varying concentrations of fluorine were tested for their sensing property to NO2gas. Both of them show good repeatability and stability. A smaller recovery time was seen in the F-MoS2-1 sample with a little amount of F loading, which was three times quicker than that of pure MoS2. The key reason for the quicker recovery time of this material was found to be the fluorine ions that had been adsorbed on the surface of F-MoS2-1 would take up some of the NO2adsorption site. Additionally, the sample F-MoS2-2 with a higher F doping level demonstrated increased sensitivity. The F-MoS2-2 sensor’s high sensitivity was mostly due to the lattice fluorine filled to the sulfur vacancy, which generated impurity levels and reduced the energy required for its electronic transition. This study might contribute to the development of new molybdenum sulfide based gas sensor.
The role of oxygen incorporation in Ni (111) substrates on the growth of hexagonal boron nitride monolayers
Authors: Li Yuan , Gomez Hector , Tran Jason , He Yanwei , Shou Chengyun , Yang Tianchen , Wei Peng , Lake Roger K , Liu Jianlin
Published: September 2023

Reliable and controllable growth of two-dimensional (2D) hexagonal boron nitride (h-BN) is essential for its wide range of applications. Substrate engineering is one of the critical factors that influence the growth of the epitaxial h-BN films. Here, we report the growth of monolayer h-BN on Ni (111) substrates incorporated with oxygen atoms via molecular beam epitaxy. It was found that the increase of incorporated oxygen concentration in the Ni substrate through a pretreatment process prior to the h-BN growth step would have an adverse effect on the morphology and growth rate of 2D h-BN. Under the same growth condition, h-BN monolayer coverage decreases exponentially as the amount of oxygen incorporated into Ni (111) increases. Density functional theory calculations and climbing image nudged elastic band (CI-NEB) method reveal that the substitutional oxygen atoms can increase the diffusion energy barrier of B and N atoms on Ni (111) thereby inhibiting the growth of h-BN films. As-grown large-area h-BN monolayer films and fabricated Al/h-BN/Ni (MIM) nanodevices were comprehensively characterized to evaluate the structural, optical and electrical properties of high-quality monolayers. Direct tunneling mechanism and high breakdown strength of ∼11.2 MV cm−1 are demonstrated for the h-BN monolayers grown on oxygen-incorporated Ni (111) substrates, indicating that these films have high quality. This study provides a unique example that heterogeneous catalysis principles can be applied to the epitaxy of 2D crystals in solid state field. Similar strategies can be used to grow other 2D crystalline materials, and are expected to facilitate the development of next generation devices based on 2D crystals.
Takasaki’s rational fourth Painlevé-Calogero system and geometric regularisability of algebro-Painlevé equations
Authors: Filipuk Galina , Stokes Alexander
Published: September 2023

We propose a notion of regularisation which extends Okamoto’s construction of spaces of initial conditions for the Painlevé differential equations to the class of systems with globally finite branching about movable singularities in the sense of the algebro-Painlevé property. We illustrate this regularisation first in the case of a Hamiltonian system obtained by Takasaki as part of the Painlevé-Calogero correspondence, which is related by an algebraic transformation to the fourth Painlevé equation. Through a combination of compactification, blowups and removal of certain curves we obtain a space on which the system is everywhere either regular or regularisable by certain algebraic transformations. We provide an atlas for this space in which the system has a global Hamiltonian structure, with all Hamiltonian functions being polynomial in coordinates just as in the case of the Painlevé equations on Okamoto’s spaces. We also compare the surface associated with the Takasaki system with that of the fourth Painlevé equation, showing that they are related by a combination of blowdowns and a branched double cover. We provide more examples of algebro-Painlevé equations regularised in this way and also discuss applications of this generalised construction of the space of initial conditions to the identification and classification of algebro-Painlevé equations.
Notes on a paper of Pokhozhaev
Authors: Boiti Chiara , Manfrin Renato
Published: September 2023

We prove a second order identity for the Kirchhoff equation which yields, in particular, a simple and direct proof of Pokhozhaev’s second order conservation law when the nonlinearity has the special form

(

C
1

s
+

C
2

)

−
2

. As applications, we give: an estimate of order ɛ
−4 for the lifespan T

ɛ
of the solution of the Cauchy problem with initial data of size ɛ in Sobolev spaces when the nonlinearity is given by any C
2 function

m
(
s
)
>
0

; a necessary and sufficient condition for boundedness of a second order energy of the solutions.
Artificial intelligence in breast imaging: potentials and challenges
Authors: Li Jia-wei , Sheng Dan-li , Chen Jian-gang , You Chao , Liu Shuai , Xu Hui-xiong , Chang Cai
Published: September 2023

Breast cancer, which is the most common type of malignant tumor among humans, is a leading cause of death in females. Standard treatment strategies, including neoadjuvant chemotherapy, surgery, postoperative chemotherapy, targeted therapy, endocrine therapy, and radiotherapy, are tailored for individual patients. Such personalized therapies have tremendously reduced the threat of breast cancer in females. Furthermore, early imaging screening plays an important role in reducing the treatment cycle and improving breast cancer prognosis. The recent innovative revolution in artificial intelligence (AI) has aided radiologists in the early and accurate diagnosis of breast cancer. In this review, we introduce the necessity of incorporating AI into breast imaging and the applications of AI in mammography, ultrasonography, magnetic resonance imaging, and positron emission tomography/computed tomography based on published articles since 1994. Moreover, the challenges of AI in breast imaging are discussed.
Power-law spectrum-based objective function to train a generative adversarial network with transfer learning for the synthetic breast CT image
Authors: Kim Gihun , Baek Jongduk
Published: September 2023

Objective. This paper proposes a new objective function to improve the quality of synthesized breast CT images generated by the GAN and compares the GAN performances on transfer learning datasets from different image domains. Approach. The proposed objective function, named beta loss function, is based on the fact that x-ray-based breast images follow the power-law spectrum. Accordingly, the exponent of the power-law spectrum (beta value) for breast CT images is approximately two. The beta loss function is defined in terms of L1 distance between the beta value of synthetic images and validation samples. To compare the GAN performances for transfer learning datasets from different image domains, ImageNet and anatomical noise images are used in the transfer learning dataset. We employ styleGAN2 as the backbone network and add the proposed beta loss function. The patient-derived breast CT dataset is used as the training and validation dataset; 7355 and 212 images are used for network training and validation, respectively. We use the beta value evaluation and Fréchet inception distance (FID) score for quantitative evaluation. Main results. For qualitative assessment, we attempt to replicate the images from the validation dataset using the trained GAN. Our results show that the proposed beta loss function achieves a more similar beta value to real images and a lower FID score. Moreover, we observe that the GAN pretrained with anatomical noise images achieves better equality than ImageNet for beta value evaluation and FID score. Finally, the beta loss function with anatomical noise as the transfer learning dataset achieves the lowest FID score. Significance. Overall, the GAN using the proposed beta loss function with anatomical noise images as the transfer learning dataset provides the lowest FID score among all tested cases. Hence, this work has implications for developing GAN-based breast image synthesis methods for medical imaging applications.
Tensor-conductance model for reducing the computational artifact in target tissue for low-frequency dosimetry
Authors: Diao Yinliang , Liu Li , Deng Nuo , Lyu Shilei , Hirata Akimasa
Published: September 2023

Objective. In protecting human from low-frequency (<100 kHz) exposure, an induced electric field strength is used as a physical quantity for assessment. However, the computational assessment suffers from a staircasing error because of the approximation of curved boundary discretized with cubic voxels. The international guidelines consider an additional reduction factor of 3 when setting the limit of external field strength computed from the permissible induced electric field. Here, a new method was proposed to reduce the staircasing error considering the tensor conductance in human modeling for low-frequency dosimetry. Approach. We proposed a tensor-based conductance model, which was developed on the basis of the filling ratio and the direction of the tissue interface to satisfy the electric field boundary condition and reduce staircasing errors in the target tissue of a voxel human model. Main results. The proposed model was validated using two-layer nonconcentric cylindrical and spherical models with different conductivity contrasts. A comparison of induced electric field strengths with solutions obtained using an analytical formula and finite element method simulation indicated that for a wide range of conductivity ratios, staircasing errors were reduced compared with a conventional scalar-potential finite-difference method. The induced electric field in a simple anatomical head model using our approach was in good agreement with finite element method for exposure to uniform magnetic field exposure and that from coil, simulating transcranial magnetic stimulation. Significance. The proposed tensor-conductance model demonstrated that the staircasing error in an inner target tissue of a voxel human body can be reduced. This finding can be used for the electromagnetic compliance assessment and dose evaluation in electric or magnetic stimulation at low frequencies.
Oil–water interface dynamics and electrical breakdown in pulsed electric field
Authors: Panov V A , Kulikov Yu M , Vetchinin S P , Pecherkin V Ya , Vasilyak L M
Published: September 2023

The motion of immiscible liquids and electrical breakdown at the interface of two horizontal layers of conducting water and transformer oil are studied under vertically oriented nonuniform pulsed electric field. The interface profile is tracked during experiments and shows the appearance and growth of a water cone inside the oil. After the water cone reaches the high voltage electrode located in the oil, three scenarios are observed depending on water conductivity and pulsed voltage amplitude: electrical current flows over the water without plasma formation; plasma onset occurs due to thermal breakdown in the water at the moment the cone tip touches the sphere; plasma onset occurs due to breakdown through a swarm of small water drops atomized from the cone tip under the action of electrical forces. From experiments and numerical simulations, the breakdown time is determined depending on applied voltage amplitude; the oil–water interface behavior in the electric field is analysed; and the electrical force distribution is studied. The experiment and simulation results show good agreement.
Superconducting properties of new hexagonal and noncentrosymmetric cubic high entropy alloys
Authors: Motla K , Arushi  , Jangid S , Meena P K , Kushwaha R K , Singh R P
Published: September 2023

Superconducting high-entropy alloys (HEAs) are a newly burgeoning field of unconventional superconductors and raise intriguing questions about the presence of superconductivity in highly disordered systems, which lack regular phonon modes. In our study, we have synthesized and investigated the superconducting characteristics of two new transition elements based HEAs Re0.35Os0.35Mo0.10W0.10Zr0.10 crystallizing in noncentrosymmetric α-Mn structure, and Ru0.35Os0.35Mo0.10W0.10Zr0.10 crystallizing in hexagonal closed-packed structure (hcp). Due to its high hardness, transition-metal-based hexagonal hcp HEA is rare and highly desirable for practical applications. Bulk magnetization, resistivity, and specific heat measurements confirmed bulk type-II superconductivity in both alloys. Specific heat analysis up to the measured low-temperature range suffices for a Bardeen-Cooper-Schrieffer explanation.
Finite-time synchronization of fractional-order chaotic system based on hidden attractors
Authors: Yan Shaohui , Zhang Hanbing , Jiang Defeng , Jiang Jiawei , Cui Yu , Zhang Yuyan
Published: September 2023

A new 3D fractional-order chaotic system is obtained by improving the Sprott-A system and introducing the definition of fractional calculus to it. Then the new system is certified to be chaotic by studying and analyzing the phase diagram, Lyapunov exponents, and smaller alignment index tests. Then the analysis of equilibrium points finds that the new system has virtually no equilibrium points and hidden attractors. The new system is dynamically analyzed by bifurcation diagram, time-domain waveform and complexity, it is indicated that the system is susceptible to initial conditions, and with the changes of different parameters the system produced different scroll types of attractors. In addition, to verify the feasibility of the system, a simulation circuit design based on Multisim is therefore carried out. Finally, the finite-time synchronization of the fractional-order system is successfully achieved by taking advantage of the high security of the hidden attractors.
Analysis of spatial damage characteristics of rock under multiple high-voltage pulse discharges: I. Cross-section characteristics
Authors: Zhao Yong , Zhang Qin , Liu Yi , Huang Shijie , Wang Tianyu , Liu Siwei , Lin Fuchang
Published: September 2023

Rock breaking by high-voltage pulse discharge (rock breaking by high-voltage pulse discharge, RHPD) is an efficient technology for rock breaking. A single discharge will lead to the initiation or expansion of cracks inside the rock, and the expansion of cracks after multiple discharges will lead to the destabilization of the rock and finally produce a fractured zone. Because of the difficulty in quantifying the spatial damage characteristics of the fractured zone, in this paper, based on the discrete element method and theoretical analysis, the spatial damage model (spatial damage model, SDM) of rock is established. For a typical liquid-solid combination, from the microscopic point of view, the damage characteristics of the fractured zone on the radial cross-section of the plasma are quantified. The changing characteristics of the damage characteristics were analyzed for multiple discharges. In addition, an experimental platform has been built, and the accuracy of the SDM has been verified by the experimental results. The results show that the increase in the discharge distance will improve the deposition energy and crushing effect, and will also improve the accuracy of the model. The findings of this paper provide a technical reserve for the application of RHPD.
A new chaotic jerk system with hidden heart-shaped attractor: dynamical analysis, multistability, connecting curves and its application in image encryption
Authors: Vivekanandhan Gayathri , Natiq Hayder , Ghaffari Aboozar , Bayani Atiyeh , Rajagopal Karthikeyan , Jafari Sajad
Published: September 2023

Application of chaos in modeling natural phenomena and encryption encourages researchers to design new chaotic systems with exciting features. Here a chaotic jerk oscillator with different properties is proposed. Previous studies mainly used non-polynomial and piecewise linear terms to design the attractors’ shape. In the paper, the heart-shaped attractor is designed using just polynomial terms. This system is studied by considering its bifurcation diagram, Lyapunov exponent, and basin of attraction. These tools show that the proposed system has chaotic and periodic attractors that coexist in some parameter intervals. The oscillator does not have an equilibrium and has a heart-shaped attractor. Moreover, the connecting curves of the oscillator are considered to explore other structural properties. Numerical results confirm the analytical solutions for the system’s connecting curves. The interesting dynamics of the oscillator are used in an encryption and compression application.
Some aspects of an exponential f(R) modified gravity
Authors: Rezaei Amir H , Azizi T , Rashidi N
Published: September 2023

In this paper, we consider an exponential form for f(R) modified gravity as

f
(
R
)
=

1

α

(

e

α
R

−
1
)

, where α is a parameter with the dimension of (length)2. The theory is consistent with local tests which give a bound on the value of this parameter: α ≤ 2 × 10−6. We investigate the static solution of this model corresponding to the Schwarzschild-de Sitter space. We also study the Jordan and Einstein frames of the model and obtain the scalar field potential related to the Einstein frame. In this respect, the mass of the scalar field is calculated as a function of Ricci curvature. Furthermore, by performing a dynamical system approach, we investigate the dimensionless parameters in the model and study the stability of the critical points in the phase space. Finally, we study the realization of inflation in this model and its graceful exit.
An optimal adaptive S-transform time-frequency space model for electromagnetic interference complexity evaluation
Authors: Yin Baiqiang , Deng Fangwen , Wang Ruoyu , Yuan Lifen , Li Bing , Zuo Lei
Published: September 2023

The issue of significant amplitude shifting with frequency in the evaluation of electromagnetic interference complexity using the S-transform can result in inaccurate extraction of energy occupancy evaluation parameters. This paper proposes a method of electromagnetic environment complexity evaluation based on the optimal adaptive S-transform (OAST) time-frequency space model. Firstly, the flexible adjustment of the window width of the S-transform window function is achieved by introducing adaptive parameters, so as to suppress the large migration of the amplitude characteristics with the signal frequency. Then, the calculation formulae for the evaluation parameters of time occupation, frequency occupation and energy occupation based on OAST are derived, and the OAST time-frequency spatial evaluation model is established; Finally, the qualitative and quantitative evaluation criteria of subjective and objective complexity based on the OAST time-frequency spatial model are analyzed and determined, overcoming the limitations of the independent grading of the traditional electromagnetic interference complexity evaluation parameters. Simulation and experimental results show that OAST can accurately extract the time-frequency energy occupation parameters and the feature parameters in the time-frequency domain are more accurate; the OAST time-frequency spatial model can evaluate the signal complexity level more accurately, and the evaluation experiments verify the correctness of the proposed method.
Tailored microwave absorption performance through interface evolution by in-situ reduced Fe nanoparticles on the surface of FeSiAl microflake
Authors: Shi Shuyan , Liu Hongjin , Cheng Hang , Zhang Longyan , Liu Xianguo
Published: September 2023

Poor impedance matching and low-frequency magnetic resonance are great challenge for Fe-based micron-scale materials as microwave absorber in GHz range. Here, we propose in situ interface engineer strategy for tailoring the interface through in situ reduced Fe nanoparticles and introduce planar anisotropy for flattening particles with high aspect ratio during high-energy vertical ball milling process, which can synchronously enhance impedance matching and exceed Snoke’s limit. With increasing milling time, the interface experiences the following in situ evolution: the nano oxide layer-micro particles interface, the partial interface between nano oxide layer and Fe nanoparticles, the integrity Fe nanoparticles-oxide layer interface, the nano oxide layer-microflake interface. Meanwhile, the aspect ratio is up to 74.93. The evolution of interface and high aspect ratio can effectively tailor permittivity and permeability. Due to the novel microstructure that FeSiAl flake are covered by ∼ 30 nm oxide layer containing ∼ 10 nm Fe nanoparticles, natural resonance induced by planar anisotropy, eddy current loss of metallic microflake, relaxation loss induced by interface polarization, conductive loss from electric resistivity together led to good microwave absorption performance (effective absorbing bandwidth of 3.12 GHz at 3.2 mm and minimal reflection loss of −44.47 dB at 7.44 GHz and 3.3 mm). The present finding might highlight for developing the composite absorbers with multi loss type coupling across nano-micro scales.
Wavelet methods for fractional electrical circuit equations
Authors: Tural-Polat Sadiye Nergis , Dincel Arzu Turan
Published: September 2023

Classical electric circuits consists of resistors, inductors and capacitors which have irreversible and lossy properties that are not taken into account in classical analysis. FDEs can be interpreted as basic memory operators and are generally used to model the lossy properties or defects. Therefore, employing fractional differential terms in electric circuit equations provides accurate modelling of those circuit elements. In this paper, the numerical solutions of fractional LC, RC and RLC circuit equations are considered to better model those imperfections. To this end, the operational matrices for Bernoulli and Chebyshev wavelets are used to obtain the numerical solutions of those fractional circuit equations. Chebyshev wavelets are orthogonal, and under some circumstances, Bernoulli wavelets can be orthogonal. The wavelet methods’ quick convergence and minimal processing load depend on the orthogonality principle. In the proposed method, those FDEs are transformed into algebraic equation systems using operational matrices employing the discrete Wavelets. The performance of those two wavelet methods are compared and contrasted for computational load, speed, and absolute error values. The paper exploits discrete Bernoulli and Chebyshev wavelets for the numerical solution of fractional LC, RC and RLC circuit equations. The fast convergence, low processing burden, and compactness of the Bernoulli and Chebyshev wavelet methods for fractional circuit equation solutions represent the novel contributions of this paper. Numerical solutions and comparisons are also presented to validate the method.
An image reconstruction algorithm for spectral exterior CT problem based on edge-preserving diffusion and edge-preserving smoothing
Authors: Qin Yanwei , Sun Tianjiao , Lu Xin , Yu Xinran , Zhao Yunsong , Zhao Xing
Published: September 2023

The exterior CT problem is a special x-ray CT imaging problem, which is often used for nondestructive inspections of large tubular samples. It can image a pipeline wall with a relatively small detector. However, exterior imaging is challenging owing to the incomplete data obtained. In this paper, we propose a regularization model for the exterior CT problem, in which an edge-preserving diffusion and edge-preserving smoothing regularizer is employed. In addition, the polychromatic characteristic of the emitted x-rays is also considered so that the model is closer to the actual physical process. Using the linearization strategy, a corresponding solution algorithm is derived. The proposed model and the algorithm are verified with both simulated data and real data. It is shown that the two type of artifacts, exterior problem artifacts and beam-hardening artifacts, can be effectively suppressed.
General diffraction integral for converging freeform vectorial fields
Authors: González-Acuña Rafael G , Thibault Simon
Published: September 2023

Herein it is presented a new vector diffraction integral capable to compute the diffraction patterns for aspheric and freeform wavefronts, with different pupil shapes, and different polarization states. The aforementioned vector diffraction integral is based on the energy conservation theorem, the far field approximation, and the angular spectrum representation of optical fields. The integral is validated through illustrative examples whose results are as expected and coincides with the related works.
Study on the methane dehydrogenation reaction catalyzed by triangular transition metal: a theoretical research
Authors: Liu Hongxia , Ling Fu , Chaozheng He
Published: September 2023

The relative stability, reaction potential energy surface, naturally bonded orbit (NBO) charge analysis, and kinetic properties of triangular transition metal catalysts in methane dehydrogenation reaction were studied by density functional theory calculation. The calculation results indicate that the process of triangular metal adsorption of methane is physical adsorption, and the main products of the reaction are hydrogen and carbon-based materials. This reaction is a multicomponent reaction. NBO charge analysis indicates the feasibility of the catalytic reaction of methane dehydrogenation. We also calculated the rate constant which indicates that the rate constant has a positive temperature dependence. Our calculations show that the reaction is an exothermic reaction catalyzed by triangular transition metal catalyzer.
Hydrodynamical simulations of galaxy formation with non-Gaussian initial conditions
Authors: Stahl Clément , Dubois Yohan , Famaey Benoit , Hahn Oliver , Ibata Rodrigo , Kraljic Katarina , Montandon Thomas
Published: September 2023

Collisionless simulations of structure formation with significant local primordial non-Gaussianities at Mpc scales have shown that a non-Gaussian tail favouring underdensities, with a negative f
NL parameter, can significantly change the merging history of galaxy-sized dark matter halos, which then typically assemble later than in vanilla ΛCDM. Moreover, such a small-scale negative f
NL could have interesting consequences for the cosmological S
8 tension. Here, we complement our previous work on collisionless simulations with new hydrodynamical simulations of galaxy formation in boxes of 30 Mpc/h, using the RAMSES code. In particular, we show that all feedback prescriptions being otherwise identical, simulations with a negative f
NL ∼ -1000 on small scales, hence forming galaxies a bit later than in vanilla ΛCDM, allow to form simulated galaxies with more disky kinematics than in the vanilla case. Therefore, such small-scale primordial non-Gaussianities could potentially help alleviate, simultaneously, tensions in cosmology and galaxy formation. These hydrodynamical simulations on small scales will need to be complemented with larger box simulations with scale-dependent non-Gaussianities, to statistically confirm these trends and explore their observational consequences in further detail.
An Introduction to High Contrast Differential Imaging of Exoplanets and Disks
Authors: Follette Katherine B.
Published: September 2023

This tutorial is an introduction to High-Contrast Imaging, a technique that enables astronomers to isolate light from faint planets and/or circumstellar disks that would otherwise be lost amidst the light of their host stars. Although technically challenging, high-contrast imaging allows for direct characterization of the properties of circumstellar sources. The intent of the article is to provide newcomers to the field a general overview of the terminology, observational considerations, data reduction strategies, and analysis techniques high-contrast imagers employ to identify, vet, and characterize planet and disk candidates.
Scheme of negative acoustic radiation force based on a multiple-layered spherical structure
Authors: Gong 宫 Menyang 门阳 , Xu 徐 Xin 鑫 , Qiao 乔 Yupei 玉配 , Liu 刘 Jiehui 杰惠 , He 何 Aijun 爱军 , Liu 刘 Xiaozhou 晓宙
Published: September 2023

Acoustic radiation force (ARF), as an important particle manipulation method, has been extensively studied in recent years. With the introduction of the concept of “acoustic tweezers”, negative acoustic radiation has become a research hotspot. In this paper, a scheme of realizing negative ARF based on the multiple-layered spherical structure design is proposed. The specific structure and design idea are presented. Detailed theoretical calculation analysis is carried out. Numerical simulations have been performed to verify the correctness of this prediction. The conjecture that the suppression of backscattering can achieve negative ARF is verified concretely, which greatly expands the application prospect and design ideas of the ARF. This work has laid a theoretical foundation for realizing precise control of the structure.
Calibration of quantitative rescattering model for simulating vortex high-order harmonic generation driven by Laguerre–Gaussian beam with nonzero orbital angular momentum
Authors: Han 韩 Jiaxin 嘉鑫 , Guan 管 Zhong 仲 , Wang 汪 Beiyu 倍羽 , Jin 金 Cheng 成
Published: September 2023

We calibrate the macroscopic vortex high-order harmonic generation (HHG) obtained by the quantitative rescattering (QRS) model to compute single-atom induced dipoles against that by solving the time-dependent Schrödinger equation (TDSE). We show that the QRS perfectly agrees with the TDSE under the favorable phase-matching condition, and the QRS can accurately predict the main features in the spatial profiles of vortex HHG if the phase-matching condition is not good. We uncover that harmonic emissions from short and long trajectories are adjusted by the phase-matching condition through the time-frequency analysis and the QRS can simulate the vortex HHG accurately only when the interference between two trajectories is absent. This work confirms that it is an efficient way to employ the QRS model in the single-atom response for precisely simulating the macroscopic vortex HHG.
On the generation of high-quality Nyquist pulses in mode-locked fiber lasers
Authors: Ren 任 Yuxuan 俞宣 , Ge 葛 Jinman 锦蔓 , Li 李 Xiaojun 小军 , Peng 彭 Junsong 俊松 , Zeng 曾 Heping 和平
Published: September 2023

Nyquist pulses have wide applications in many areas, from electronics to optics. Mode-locked lasers are ideal platforms to generate such pulses. However, how to generate high-quality Nyquist pulses in mode-locked lasers remains elusive. We address this problem by managing different physical effects in mode-locked fiber lasers through extensive numerical simulations. We find that net dispersion, linear loss, gain and filter shaping can affect the quality of Nyquist pulses significantly. We also demonstrate that Nyquist pulses experience similariton shaping due to the nonlinear attractor effect in the gain medium. Our work may contribute to the design of Nyquist pulse sources and enrich the understanding of pulse shaping dynamics in mode-locked lasers.
A 1-bit electronically reconfigurable beam steerable metasurface reflectarray with multiple polarization manipulations
Authors: Shi 史 Yan 琰 , Xu 徐 Xi-Ya 茜雅 , Wang 王 Shao-Ze 少泽 , Wei 魏 Wen-Yue 文岳 , Wu 武 Quan-Wei 全伟
Published: September 2023

A 1-bit electronically controlled metasurface reflectarray is presented to achieve beam steering with multiple polarization manipulations. A metsurface unit cell loaded by two PIN diodes is designed. By switching the two PIN diodes between ON and OFF states, the isotropic and anisotropic reflections can be flexibly achieved. For either the isotropic reflection or the anisotropic reflection, the two operation states achieve the reflection coefficients with approximately equal magnitude and 180° out of phase, thus giving rise to the isotropic/anisotropic 1-bit metasurface unit cells. With the 1-bit unit cells, a 12-by-12 metasurface reflectarray is optimally designed and fabricated. Under either y- or x-polarized incident wave illumination, the reflectarray can achieve the co-polarized and cross-polarized beam scanning, respectively, with the peak gains of 20.08 dBi and 17.26 dBi within the scan range of about ±50°. With the right-handed circular polarization (RHCP) excitation, the left-handed circular polarization (LHCP) radiation with the peak gain of 16.98 dBic can be achieved within the scan range of ±50°. Good agreement between the experimental results and the simulation results are observed for 2D beam steering and polarization manipulation capabilities.
Adaptive octree meshes for simulation of extracellular electrophysiology
Authors: B C Girard Christopher , Song Dong
Published: September 2023

Objective. The interaction between neural tissues and artificial electrodes is crucial for understanding and advancing neuroscientific research and therapeutic applications. However, accurately modeling this space around the neurons rapidly increases the computational complexity of neural simulations. Approach. This study demonstrates a dynamically adaptive simulation method that greatly accelerates computation by adjusting spatial resolution of the simulation as needed. Use of an octree structure for the mesh, in combination with the admittance method for discretizing conductivity, provides both accurate approximation and ease of modification on-the-fly. Main results. In tests of both local field potential estimation and multi-electrode stimulation, dynamically adapted meshes achieve accuracy comparable to high-resolution static meshes in an order of magnitude less time. Significance. The proposed simulation pipeline improves model scalability, allowing greater detail with fewer computational resources. The implementation is available as an open-source Python module, providing flexibility and ease of reuse for the broader research community.
Lepton Flavour Universality tests in b → clν decays at LHCb
Authors: Mohammed R. ,   the LHCb collaboration
Published: September 2023

The Standard Model predicts that the electroweak couplings to the three charged leptons are identical. However, in the last decade, experimental measurements have suggested that semileptonic processes involving taus could have a slightly enhanced decay rate compared to their muonic counterparts. If confirmed, this would be an unambiguous sign of New Physics, with various scenarios introducing additional interactions that couple preferentially to the third generation. Two recent lepton universality tests performed at LHCb are presented in these proceedings of the first edition of the New Frontiers in Lepton Flavour workshop.
The potential of a TeV-scale muon-ion collider
Authors: Acosta D. , Barberis E. , Hurley N. , Li W. , Miguel Colin O. , Wang Y. , Wood D. , Zuo X.
Published: September 2023

We propose the development of a novel muon-proton and
muon-nucleus collider facility at the TeV scale that is capable of
performing precision deep inelastic scattering measurements in new
regimes and providing a rich program in nuclear and particle
physics. Such a facility could seed, or leverage, the development of
a muon-antimuon collider and make use of the existing hadron
accelerator infrastructure when sited at a facility such as
Brookhaven National Laboratory, Fermilab, or CERN. We discuss the
possible energy and luminosity design parameters for several
collider configurations, and illustrate the science potential with
several studies on deep inelastic scattering kinematics, Higgs and
vector boson production, top quark production, and beyond Standard
Model leptoquark production. Detector design considerations and a
possible road map toward development are also given.
Weather pattern conducive to the extreme summer heat in North China and driven by atmospheric teleconnections
Authors: Xie Tiejun , Ding Ting , Wang Ji , Zhang Yingjuan , Gao Hui , Zhao Xiulan , Zhao Liang
Published: September 2023

Extreme summer heat can have severe socioeconomic impacts and has occurred frequently in North China in recent years, most notably in June–July 2023, when North China experienced the most widespread, persistent, and high-intensity extreme heat on record. Here, typical weather patterns covering North China and its surrounding areas were classified into seven types based on the Cost733class package, and the weather pattern type 4 (T4), characterized by the strengthened ridge and anticyclone anomaly in northeastern China, was found as the most favorable for the occurrence of extreme summer heat in North China (NCSH). Diagnostic and wave activity flux analyses indicate that the Eurasian teleconnection (EAT) pattern from the atmosphere and the Victoria mode (VM) from the ocean are the top two dominant climate drivers of the T4 weather pattern. The empirical models constructed based on the EAT and the VM can effectively simulate the number of days of the T4 weather pattern and the NCSH, respectively. Our results suggest that, with the help of the seasonal forecast from climate models, the EAT and the VM can be used to predict the number of days of the T4 weather pattern and the NCSH for the coming summer, enabling us to protect human health and reduce its socioeconomic impacts through proactive measures in advance.
The effect of thermal aging on flexural strength of CAD/CAM hybrid and polymeric materials
Authors: Yeslam Hanin E , Alharbi Shadia , Albalawi Waad , Hasanain Fatin A
Published: September 2023

The field of dentistry is consistently innovating with the introduction of novel hybrid and polymer materials for computer-aided design and manufacturing (CAD/CAM). It is noteworthy that the temperature within the oral cavity has a significant impact on the strength of new biomaterials utilized for CAD/CAM fabrication of fixed partial dentures (FPDs). Studies have demonstrated that alterations in intraoral temperature may significantly affect the longevity and durability of dental restorative materials. This study aimed to evaluate the flexural strength, flexural modulus, and effect of thermal aging on CAD/CAM restorative materials. Five CAD/CAM materials were investigated: nano-ceramic-hybrid (GR), polymer-infiltrated-ceramic-network (VE), polyether-ether-ketone (PK), fiberglass-reinforced epoxy-resin (CT), and Feldspar Ceramic (VB). A total of 100 bar-shaped specimens were prepared (N = 20). Each group was subdivided into thermocycling (TC) and no-thermocycling (NTC) subgroups (n = 10). All the specimens underwent a 3-point bending test. The mean flexural strengths and moduli were statistically analyzed using paired t-test, analysis of variance (ANOVA), and Bonferroni pair-wise comparison (p < 0.05). Significant differences were observed in the flexural strength (FS) and modulus (E) between the materials (p < 0.001). GR had the highest FS among tested hybrid materials. NTC CT had the highest FS (924.88 ± 120.1 MPa), followed by GR (385.13 ± 90.73 MPa), then PK (309.56 ± 46.84 MPa). The FS of brittle ceramic VB was the lowest (p < 0.001), but similar to that of PICN VE. Only resin-containing VE and CT significantly decreased in E after thermocycling (p < 0.01, p = 0.013), showing the softening effect of thermocycling on their resin matrix. It can be concluded that new hybrid materials (GR) had higher flexural strength than feldspar ceramic and other resin/polymeric CAD/CAM materials. Polymeric PEEK and GR hybrid materials were resistant to significant deleterious effects of TC. Therefore, they would be appropriate for situations with a higher stress load.
Efficient parallelization of quantum basis state shift
Authors: Budinski Lj , Niemimäki O , Zamora-Zamora R , Lahtinen V
Published: September 2023

Basis state shift is central to many quantum algorithms, most notably the quantum walk. Efficient implementations are of major importance for achieving a quantum speedup for computational applications. We optimize the state shift algorithm by incorporating the shift in different directions in parallel. This provides a significant reduction in the depth of the quantum circuit in comparison to the currently known methods, giving a linear scaling in the number of gates versus working qubits in contrast to the quadratic scaling of the state-of-the-art method based on the quantum Fourier transform. For a one-dimensional array of size 2
n
for n > 4, we derive the total number of

15
n
+
74

two-qubit CX gates in the parallel circuit, using a total of

2
n
−
2

qubits including an ancilla register for the decomposition of multi-controlled gates. We focus on the one-dimensional and periodic shift, but note that the method can be extended to more complex cases.