bluuebunny/crossref_metadata_2025_split huggingface dataset:
Electric field simulation, structure and properties of nanofiber- coated yarn prepared by multi-needle water bath electrospinning
Authors: Wang Xiaohu , Zhou Xinru , Zhao Xiaoman , Han Xiao , Hong Jianhan 
Published: October 2024

Abstract
To address the issue of low yield in the preparation of nanofiber materials using single-needle electrospinning technology, multi-needle electrospinning technology has emerged as a crucial solution for mass production. However, the mutual interference of multiple electric fields between the needles can cause significant randomness in the morphology of the produced nanofibers. To better predict the influence of electric field distribution on nanofiber morphology, simulation analysis of the multi-needle arrangement was conducted using finite element analysis (FEA) software. Nanofiber-coated yarn was produced continuously with the core yarn rotating. The water bath was utilized as the receiver of nanofibers on self-made water bath electrospinning equipment. The electric field distribution and mutual interference under seven different needle arrangements was simulated and analyzed by FEA software ANSYS Maxwell. The results indicated that when the needles were arranged diagonally in a staggered pattern and directly above the core yarn, the simulated electric field distribution was relatively uniform, with less mutual interference. The produced nanofibers exhibited a finer diameter and the diameter distribution was more concentrated. In addition, the nanofiber coating showed higher crystallinity and better mechanical properties.
MoS2 high temperature sensitive element with a single Si3N4 protective layer
Authors: Kong Lingbing , Li Yuning , Wang Yuqiang , Deng Tao 
Published: October 2024

Abstract
Temperature sensors have extensive applications in industrial production, defense, and military sectors. However, conventional temperature sensors are limited to operating temperatures below 200 °C and are unsuitable for detecting extremely high temperatures. In this paper, a method for thermal protection of molybdenum disulfide (MoS2) films is proposed and a MoS2 high temperature sensor is prepared. By depositing silicon nitride (Si3N4) films onto monolayer MoS2, not only is the issue of high-temperature oxidation effectively addressed, but also the prevention of contamination by impurities that could potentially compromise the performance of MoS2. Moreover, the width of the Schottky barrier of metal/MoS2 is reduced by using plasma-enhanced chemical vapor deposition of 400 nm Si3N4 to form an ohmic contact, which improves the electrical performance of the device by three orders of magnitude. The sensor exhibits a positive temperature coefficient measurement range of 25 °C–550 °C, with a maximum temperature coefficient of resistance of 0.89%·°C−1. The thermal protection method proposed in this paper provides a new idea for the fabrication of high-temperature sensors, which is expected to be applied in the high-temperature field.
Convex integration solution of two-dimensional hyperbolic Navier–Stokes equations*
Authors: Wu Jiahong , Yamazaki Kazuo 
Published: October 2024

Abstract
Hyperbolic Navier–Stokes equations replace the heat operator within the Navier–Stokes equations with a damped wave operator. Due to this second-order temporal derivative term, there exist no known bounded quantities for its solution; consequently, various standard results for the Navier–Stokes equations such as the global existence of a weak solution, that is typically constructed via Galerkin approximation, are absent in the literature. In this manuscript, we employ the technique of convex integration on the two-dimensional hyperbolic Navier–Stokes equations to construct a weak solution with prescribed energy and thereby prove its non-uniqueness. The main difficulty is the second-order temporal derivative term, which is too singular to be estimated as a linear error. One of our novel ideas is to use the time integral of the temporal corrector perturbation of the Navier–Stokes equations as the temporal corrector perturbation for the hyperbolic Navier–Stokes equations.
First test beam of the DMAPS-based proton tracker at the pMBRT facility at the Curie Institute
Authors: Granado-González M , Price T , Gonella L , Moustakas K , Hirono T , Hemperek T , De Marzi L , Patriarca A 
Published: October 2024

Abstract

Objective. Proton radiotherapy’s efficacy relies on an accurate relative stopping power (RSP) map of the patient to optimise the treatment plan and minimize uncertainties. Currently, a conversion of a Hounsfield Units map obtained by a common x-ray computed tomography (CT) is used to compute the RSP. This conversion is one of the main limiting factors for proton radiotherapy. To bypass this conversion a direct RSP map could be obtained by performing a proton CT (pCT). The focal point of this article is to present a proof of concept of the potential of fast pixel technologies for proton tracking at clinical facilities. Approach. A two-layer tracker based on the TJ-Monopix1, a depleted monolithic active pixel sensor (DMAPS) chip initially designed for the ATLAS, was tested at the proton minibeam radiotherapy beamline at the Curie Institute. The chips were subjected to 100 MeV protons passing through the single slit collimator (

0.4
×
20

mm2) with fluxes up to

1.3
×

10
7

p s−1 cm−2. The performance of the proton tracker was evaluated with GEANT4 simulations. Main results. The beam profile and dispersion in air were characterized by an opening of 0.031 mm cm−1, and a

σ
x

=
0.172

mm at the position of the slit. The results of the proton tracking show how the TJ-Monopix1 chip can effectively track protons in a clinical environment, achieving a tracking purity close to 70

%

, and a position resolution below 0.5 mm; confirming the chip’s ability to handle high proton fluxes with a competitive performance. Significance. This work suggests that DMAPS technologies can be a cost-effective alternative for proton imaging. Additionally, the study identifies areas where further optimization of chip design is required to fully leverage these technologies for clinical ion imaging applications.
PICASSO: a universal brain phantom for positron emission tomography based on the activity painting technique
Authors: Shanina Ekaterina , Spencer Benjamin A , Li Tiantian , Huang Bangyan , Qi Jinyi , Cherry Simon R 
Published: October 2024

Abstract

Objective. This study presents a universal phantom for positron emission tomography (PET) that allows arbitrary static and dynamic activity distributions of various complexities to be generated using a single PET acquisition. Approach. We collected a high-statistics dataset (with a total of 22.4 × 109 prompt coincidences and an event density of 2.75 × 106 events mm−3) by raster-scanning a single plane with a 22Na point source mounted on a robotic arm in the field-of-view of the uEXPLORER PET/CT scanner. The source position was determined from the reconstructed dynamic frames. Uniquely, true coincidences were separated from scattered and random events based on the distance between their line-of-response and the known source location. Finally, we randomly sampled the dataset to generate the desired activity distributions modeling several different phantoms. Main results. Overall, the target and the reconstructed phantom images had good agreement. The analysis of a simple geometric distribution showed high quantitative accuracy of the phantom, with mean error of <–3.0% relative to the ground truth for activity concentrations ranging from 5.3 to 47.7 kBq ml−1. The model of a high-resolution 18F-fluorodeoxyglucose distribution in the brain illustrates the usefulness of the technique in simulating realistic static neuroimaging studies. A dynamic 18F-florbetaben study was modeled based on the time-activity curves of a human study and a segmented brain phantom with no coincidences repeating between frames. For all time points, the mean voxel-wise errors ranged from –4.4% to –0.7% in grey matter and from −3.9% to +2.8% in white matter. Significance. The proposed phantom technique is highly flexible and allows modeling of static and dynamic brain PET studies with high quantitative accuracy. It overcomes several key limitations of the existing phantoms and has many promising applications for the purposes of image reconstruction, data correction methods, and system performance evaluation, particularly for new high-performance dedicated brain PET scanners.
Performance evaluation of an inorganic optical fibre dosimeter for use in external beam radiotherapy with pulsed beams
Authors: McDonnell C , McLaughlin O , McGarry C K , Hounsell A R , O’Keeffe S , Lewis E , Prise K M 
Published: October 2024

Abstract

Objective. Optical fibre dosimeters (OFDs) offer great promise for real-time in vivo dose measurement in radiation-based treatment modalities such as radiotherapy and brachytherapy. This is attributed to their many useful qualities such as high spatial resolution and sensitivity. However, there are several requirements that an optical fibre dosimeter must meet to be acceptable for dose measurement in a specified treatment modality. In this work, the dosimetric performance of a novel optical fibre dosimeter for use in external beam radiotherapy is presented. Approach. The dosimeter was characterised for photon beam energies between 6–15 MV using a Varian TrueBeam Linac at dose rates between 100–2400 MU/min and assessed based on its repeatability, dose dependence, dose rate dependence, energy dependence and dose-per-pulse dependence. Main Results. The results demonstrated excellent short-term repeatability of 0.3

%

, good linearity in response (

R

2

>

0.9997), and minor dose rate dependence between 0.53%–2.49% for all beam qualities investigated. As the scintillator of the OFD is non-water equivalent, Monte-Carlo-TOPAS simulations were used to calculate the absorbed dose energy dependence. A dose-per-pulse dependence was also investigated and compared with dosimetry measurements made with an ionisation chamber and simulated from the treatment planning system. An over-response of 20

%

was found at the lowest investigated dose-per-pulse, and an under-response of 34

%

was found at the highest investigated dose-per-pulse. This is believed to be due to an intrinsic energy dependence making this type of OFD unsuitable for external beam radiotherapy dosimetry. Significance. The OFD evaluated in this work was primarily designed for high-dose-rate brachytherapy whereas this study includes the first measurements made in external beam radiotherapy and highlights the challenges of transferability of the dosimeter to a different radiation source.
Multi-functional periodically heterogeneous structures for energy harvesting and vibration attenuation-effects of piezoelectricity and shunting circuits
Authors: Hosseinkhani A , Rohan E 
Published: October 2024

Abstract
We explore a kind of metamaterial plate structures intended for simultaneous energy harvesting and vibration control. These structures are designed using a periodically perforated piezoelectric plate (the matrix) with elastic inclusions situated in the holes and serving for the resonators. The design options comprise two- and three-phase configurations related to the mechanical connection between the matrix and inclusions. By introducing a singularity—the focal spot created as a defect in the perfectly periodic structure and using the theory of super-cell, an enhanced piezoelectric energy harvester is obtained. It is observed that such a meta-structure serves as a dual-purpose system: efficiently capturing vibrational energy at a focal spot while maintaining the overall vibration attenuation throughout the structure. The band gap analysis based on the Bloch’s wave decomposition theory shows that by concentrating energy and halting vibration propagation, approximately 10 times energy harvesting enhancement and a remarkable 100 dB reduction in vibrations are achieved simultaneously. Besides the passive response of these meta-structures, we consider its extension by an external electric circuit (EC). Such modified configurations enable to exploit ‘actively’ the piezoelectric plate property to transmit the mechanical response between two, or more distant locations. Due to nonlocal interactions introduced by means the controllable EC, we consider optimization of the EC impedance to reduce the vibrations at a selected location of the whole structure without any external energy supply. The computational study discovers perspectives and benefits of designing such active self-powered meta-structures.
Dynamical phase transitions, caustics, and quantum dark bands
Authors: Link Valentin , Strunz Walter T , O’Dell D H J 
Published: October 2024

Abstract
We provide a new perspective on quantum dynamical phase transitions (DPTs) by explaining their origin in terms of caustics that form in the Fock space representation of the many-body state over time, using the fully connected transverse field Ising model as an example. In this way we establish a connection between DPTs in a quantum spin system and an everyday natural phenomenon: The dark band between the primary and secondary bows (caustics) in rainbows known as Alexander’s dark band. The DPT occurs when the Loschmidt echo crosses the switching line between the evanescent tails of two back-to-back Airy functions that dress neighbouring fold caustics in Fock space and is the time-dependent analogue of what is seen as a function of angle in the sky. The structural stability and universal properties of caustics, as described mathematically by catastrophe theory, explains the generic occurrence of DPTs in the model and suggests that our analysis has wide applicability. Based on our thorough analytical understanding we propose a protocol which can be used to verify the existence of a DPT in a finite system experiment.
Nonlinearity-induced symmetry breaking in a system of two parametrically driven Kerr-Duffing oscillators
Authors: Hellbach F , De Bernardis D , Saur M , Carusotto I , Belzig W , Rastelli G 
Published: October 2024

Abstract
We study the classical dynamics of a system comprising a pair of Kerr-Duffing nonlinear oscillators, which are coupled through a nonlinear interaction and subjected to a parametric drive. Using the rotating wave approximation, we analyze the steady-state solutions for the amplitudes of the two oscillators. For the case of almost identical oscillators, we investigate separately the cases in which only one oscillator is parametrically driven and in which both oscillators are simultaneously driven. In the latter regime, we demonstrate that even when the parametric drives acting on the two oscillators are identical, the system can transition from a stable symmetric solution to a broken-symmetry solution as the detuning is varied.
Fractal analyses of AlxGa1−xN thin film surfaces on AlN at different annealing temperatures
Authors: Bayırlı Mehmet , Zeybek Orhan , Ilgaz Aykut 
Published: October 2024

Abstract
The determination of heteromorphological structures formed on the surface during annealing of AlxGa1−xN thin film grown on sapphire substrate using the metal organic chemical vapor deposition technique at different temperatures was investigated by fractal analysis method. The images of the surfaces of the thin films were taken by atomic force microscopy (AFM) at temperatures of 900, 1000, 1050 and 1200 °C respectively. AFM images were digitised in bitmap format according to the annealing temperatures. It was determined that the fractal dimensions obtained a linear correlation with the annealing temperatures. The results confirm the hypothesis that surface relaxation by the thermal action can produce fractal-like structures at particle or cluster boundaries. It is found that the observed cluster formation of superficial particles decreases as increasing temperature. The increase in temperature reduces the rate of superficial particle coating. To determine the surface roughness of the AlxGa1−xN thin film according to the annealing temperature, the AFM images were digitized in tagged image file format and the statistical root mean square, mean value, mean roughness, skewness and kurtosis values of the films were calculated. The roughness is a result of the thin film surface heteromorphology formed due to the specific annealing process. It is proved that the fractal dimensions of the AlxGa1−xN thin film increase as the annealing temperature rises. The particles coalesce on the surface and cluster in different types and sizes at each different annealing temperature, forming islets of different sizes. The skewness and kurtosis values show a different and irregular change.
Dynamic analysis of a modified Leslie-Gower model with Michaelis-Menten prey harvesting and additive allee effect on predator population
Authors: Mortuja Md Golam , Chaube Mithilesh Kumar , Kumar Santosh 
Published: October 2024

Abstract
In the current study, the dynamics of a Leslie-Gower model have been studied considering the Allee effect in the growth of the predator and the Michaelis-Menten type harvesting effect on the prey from biological and theoretical perspectives. Key findings highlight how these effects influence the existence of positive equilibria, with local stability properties and potential bifurcation behaviors examined using the center manifold theorem and linearization. Criteria for saddle-node bifurcation are established through Sotomayor’s theorem, while the direction and stability of Hopf bifurcation are explored via the first Lyapunov exponent. An optimal control model is developed to promote sustainable ecosystem development, utilizing the harvesting rate as a control parameter. Further, a few numerical simulations validate our significant findings using phase portrait diagrams.
Generalized flow-composed symplectic methods
for post-Newtonian Hamiltonian systems
Authors: Huang Shixiang , Zeng Kaiming , Niu Xinghua , Mei Lijie 
Published: October 2024

Abstract
Due to the nonseparability of the post-Newtonian (PN) Hamiltonian systems of compact
objects, the symplectic methods that admit the linear error growth and the near preservation of
first integrals are always implicit as explicit symplectic methods have not been currently found
for general nonseparable Hamiltonian systems. Since the PN Hamiltonian has a particular
formulation that includes a dominant Newtonian part and a perturbation PN part, we present the
generalized flow-composed Runge-Kutta (GFCRK) method with a free parameter λ to PN
Hamiltonian systems. It is shown that the GFCRK method is symplectic once the underlying RK method
is symplectic, and it is symmetric once the underlying RK method is symmetric under the setting
λ = 1/2. Numerical experiments with the 2PN Hamiltonian of spinning compact binaries
demonstrate the higher accuracy and efficiency of the symplectic GFCRK method than the underlying
symplectic RK method in the case of weak PN effect. Meanwhile, the numerical results also support
higher efficiency of the symplectic GFCRK method than the semi-explicit mixed symplectic method of
the same order.
Search for dark matter annihilation to gamma-rays from SPT-SZ selected galaxy clusters
Authors: Manna Siddhant , Desai Shantanu 
Published: October 2024

Abstract
We search for dark matter annihilation from galaxy clusters in the energy range from 1–300 GeV using nearly 16 years of Fermi-LAT data. For this purpose, we use 350 galaxy clusters selected from
the 2500 deg2 SPT-SZ survey. We model the dark matter distribution using the NFW profile for the main halo along with the Einasto profile for the substructure. The largest signal is seen for the cluster SPT-CL J2021-5257 with a significance of around 3σ. The best-fit dark matter mass and annihilation cross-section for this cluster are equal to (60.0 ± 11.8) GeV and ⟨σv⟩ = (6.0 ± 0.6) × 10-25 cm3 s-1 for the b̅ b annihilation channel. However, this central estimate is in conflict with the limits on annihilation cross-section from dwarf spheroidal galaxies, and hence cannot be attributed to dark matter annihilation. Three other clusters show significance between 2-2.5σ, whereas all the remaining clusters show null results. The most stringent 95% c.l. upper limit for the WIMP annihilation cross-section among all the clusters is from SPT-CL J0455-4159, viz. ⟨σv⟩ = 6.44 × 10-26 cm3 s-1 for m
χ = 10 GeV and b
b̅ annihilation channel.
A new solution for the observed isotropic cosmic birefringence angle and its implications for the anisotropic counterpart through a Boltzmann approach
Authors: Greco Alessandro , Bartolo Nicola , Gruppuso Alessandro 
Published: October 2024

Abstract
Cosmic Birefringence (CB) is a phenomenon in which the polarization of the Cosmic Microwave Background (CMB) radiation is rotated as it travels through space due to the coupling between photons and an axion-like field. We look for a solution able to explain the result obtained from the Planck Public Release 4 (PR4), which has provided a hint of detection of the CB angle, α = (0.30 ± 0.11)∘. In addition to the solutions, already present in the literature, which need a non-negligible evolution in time of the axion-like field during recombination, we find a new region of the parameter space that allows for a nearly constant time evolution of such a field in the same epoch. The latter reinforces the possibility to employ the commonly used relations connecting the observed CMB spectra with the unrotated ones, through trigonometric functions of the CB angle. However, if the homogeneous axion field sourcing isotropic birefringence is almost constant in time during the matter-dominated era, this does not automatically imply that the same holds also for the associated inhomogeneous perturbations. For this reason, in this paper we present a fully generalized Boltzmann treatment of this phenomenon, that is able, for the first time to our knowledge to deal with the time evolution of anisotropic cosmic birefringence (ACB). We employ this approach to provide predictions of ACB, in particular for the set of best-fit parameters found in the new solution of the isotropic case. If the latter is the correct model, we expect an ACB spectrum of the order of (10-15 ÷ 10-32) deg2 for the auto-correlation, and (10-7 ÷ 10-17) μK·deg for the cross-correlations with the CMB T and E fields, depending on the angular scale.
Impact of spatially varying transport coefficients in EMC3-Eirene simulations of W7-X and assessment of drifts
Authors: Bold David , Reimold Felix , Niemann Holger , Gao Yu , Jakubowski Marcin , Killer Carsten , Winters Victoria R. , Maaziz Nassim ,   the W7-X Team
Published: October 2024

Abstract
Modelling the scrape-off layer of a stellarator is challenging due to the complex magnetic 3D geometry. The here presented study analyses simulations of the scrape-off layer (SOL) of the stellarator Wendelstein 7-X (W7-X) using spatially varying diffusion coefficients for the magnetic standard configuration, extending our previous study (Bold et al 2022 Nucl. Fusion
62 106011). Comparing the EMC3-Eirene simulations with experimental observations, an inconsistency between the strike-line width (SLW) and the upstream parameters was observed. While to match the experimental SLW a particle diffusion coefficient D ≈ 0.2 m2 s−1 is needed, D ≈ 1 m2 s−1 is needed to get experimental separatrix temperatures of 50 eV at the given experimental heating power. We asses the impact of physically motivated spatially varying transport coeffients. Agreement with experimental data can be improved, but various differences remain. We show that drifts are expected to help overcome the discrepancies and, thus, the development of SOL transport models including drifts is a necessary next step to study the SOL transport of the W7-X stellarator.