bluuebunny/crossref_metadata_2025_split huggingface dataset:
Sympathetically cooled highly charged ions in a radio-frequency trap with superconducting magnetic shielding
Authors: Dijck Elwin A. , Warnecke Christian , Wehrheim Malte , Henninger Ruben B. , Eff Julia , Georgiou Kostas , Graf Andrea , Kokh Stepan , Kozhiparambil Sajith Lakshmi P. , Mayo Christopher , Schäfer Vera M. , Volk Claudia , Schmidt Piet O. , Pfeifer Thomas , Crespo López-Urrutia José R. 
Published: August 2023

We sympathetically cool highly charged ions (HCI) in Coulomb crystals of Doppler-cooled Be+ ions confined in a cryogenic linear Paul trap that is integrated into a fully enclosing radio-frequency resonator manufactured from superconducting niobium. By preparing a single Be+ cooling ion and a single HCI, quantum logic spectroscopy toward frequency metrology and qubit operations with a great variety of species are enabled. While cooling down the assembly through its transition temperature into the superconducting state, an applied quantization magnetic field becomes persistent, and the trap becomes shielded from subsequent external electromagnetic fluctuations. Using a magnetically sensitive hyperfine transition of Be+ as a qubit, we measure the fractional decay rate of the stored magnetic field to be at the 10−10 s−1 level. Ramsey interferometry and spin-echo measurements yield coherence times of &gt;400 ms, demonstrating excellent passive magnetic shielding at frequencies down to DC.
Analysis of the discrepancy principle for Tikhonov regularization with oversmoothing penalty term under low order source conditions
Authors: Klinkhammer C , Plato R 
Published: August 2023

Abstract
We study the application of Tikhonov regularization to ill-posed nonlinear operator equations. The objective of this work is to prove convergence rates for the discrepancy principle under low order source conditions of logarithmic type. We work within the framework of Hilbert scales and extend existing studies on this subject to the oversmoothing case. The latter means that the exact solution of the treated operator equation does not belong to the domain of definition of the penalty term. As a consequence, the Tikhonov functional fails to have a finite value.
Computer vision assisted decomposition analysis of atom probe tomography data
Authors: Sälker Janis A , Hadian Raheleh , Schneider Jochen M , Hans Marcus 
Published: August 2023

Abstract
While atom probe tomography (APT) offers 3D spatially-resolved compositional characterization at the nanometer scale, individual inspection of large datasets is time demanding and the interpretation thereof is highly operator-dependent. Recently, the decomposition behavior of (V,Al)N thin films was investigated by APT. The conventional analysis, employing standard tools from commercial software, is laborious and only a small fraction (below 5%) of the total acquired data has been used. In the present work, the analysis workflow is automated, taking into account more than 90% of the total acquired data. As a first step, the decomposition products, including matrix and enriched phases, were identified via deep learning-based semantic image segmentation. Performance of the ‘matrix’ and the decomposition product ‘aluminum-rich’ was very good, achieving F1-scores of 0.994 and 0.943, respectively, while performance for ‘vanadium-rich’ was with 0.854 slightly lower. The segmentation enables the investigation of phase formation evolution over temperature. As a next step, early stages of the spinodal decomposition were probed on the ‘matrix’ phase by a neighborhood analysis. While results were consistent with prior work, the data analysis in this work is statistically more robust by leveraging an order of magnitude larger dataset. In the end, the transferability of the presented phase segmentation workflow of the (V,Al)N-based model is shown and discussed for the decomposition of isostructural (Ti,Al)N.
Two-photon absorption in colloidal semiconductor nanocrystals: a review
Authors: Alo Arthur , Lemus Jonathan C , Sousa Claudevan A , Nagamine Gabriel , Padilha Lazaro A 
Published: August 2023

Abstract
Large two-photon absorption (2PA) cross-section combined with high emission quantum efficiency and size-tunable bandgap energy has put colloidal semiconductor nanocrystals (NCs) on the vanguard of nonlinear optical materials. After nearly two decades of intense studies on the nonlinear optical response in quantum-confined semiconductors, this is still a vibrant field, as novel nanomaterials are being developed and new applications are being proposed. In this review, we examine the progress of 2PA research in NCs, highlighting the impact of quantum confinement on the magnitude and spectral characteristics of this nonlinear response in semiconductor materials. We show that for NCs with three-dimensional quantum confinement, the so-called quantum dots, 2PA cross-section grows linearly with the nanoparticle volume, following a universal volume scaling. We overview strategies used to gain further control over the nonlinear optical response in these structures by shape and heterostructure engineering and some applications that might take advantage of the series of unique properties of these nanostructures.
Single and multiple fault diagnosis based on PCA with relative variation of contribution strategy
Authors: Berbache Soraia , Harkat Mohamed Faouzi , Lachouri Abderrezak , Kratz Frédérik 
Published: August 2023

Abstract
Data-driven methods have been recognized as an efficient tool for multivariate statistical process control. Contribution plots are also well known as a popular tool in principal component analysis, which is used for isolating sensor faults without the need for any prior information. However, studies carried out in the literature have unified contribution plots in three general approaches. Furthermore, they demonstrated that correct diagnosis based on contribution plots is not guaranteed for either single or multiple sensor faults. Therefore, to deal with this issue, the present paper highlights a new contribution formula called relative variation of contribution. Simulation results show that the proposed method of contribution can successfully perform the fault isolation task, in comparison with partial decomposition contribution and its relative version (rPDC) based on their fault isolation rate.
Composite fault feature extraction of rolling bearing using adaptive circulant singular spectrum analysis
Authors: Zhou Hongdi , Zhu Lin , Zhong Fei , Cai Yijie 
Published: August 2023

Abstract
Aiming to extract the weak composite fault characteristics of a rolling bearing under harsh operation conditions, a novel composite fault diagnosis method for bearings based on adaptive circulant singular spectrum analysis (ACiSSA) is proposed. The proposed method is able to adaptively obtain the eigenvalue of a non-stationary vibration signal in any dimension, and effectively reassemble the same frequency components and improve the signal-to-noise ratio (SNR). Specifically, circulant singular spectrum analysis is utilized to decompose the raw signal, and the optimal parameters, i.e. the embedding dimension and threshold value of cumulative contribution, are selected to maximum kurtosis through the grey wolf optimization method. The signal is reconstructed with high SNR according to the effective singular spectrum components. Envelope demodulation analysis is then implemented to extract the characteristic defect frequency in the reconstructed signal. Finally, feature extraction performance is quantitatively evaluated, and experimental results show that the proposed ACiSSA method is able to extract more sensitive features under more noisy conditions compared with other common methods, with higher computational efficiency.
Investigation of cavitation evolvement in a pump inducer by proper orthogonal decomposition analysis of video images
Authors: Cao Ruijia , Yuan Jianping , Kong Xiangxu , Xu Zhenfa , Peng Guoyi , Qiu Ning 
Published: August 2023

Abstract
The aim of this study is to develop a contour extraction method for the investigation of the temporal and spatial characteristics of cavitation evolution in high-speed inducers. Cavitation experiments were conducted, and corresponding snapshots were captured using a high-speed camera subsequently. The raw images were processed while using threshold value filtering techniques to extract only relevant bubble information. Proper orthogonal decomposition was employed to explore the evolving characteristics in a quantitative manner. Results show that the cavitation evolution process is an unsteady process when viewed from the side. In high net positive suction head (NPSH) environments, multiple small-scale spatial modals contribute significantly to the effective proportion of the cavitation structure. The attached sheet cavitation exists in the blade edge which is the main embodiment of cavitation area evolvement. Under low NPSH conditions, the primary flow feature can be reflected by a low-mode flow pattern, associated with the inducer’s rotation effect. The evolving regulation of cavitation area in developed stage is closely submitted to the trigonometric function. And the exhibited spatial coefficient exposes the hidden reflux vortex feature. The proposed image separation techniques enable the quantification of morphological features, which can provide technical details for the digital design of inducers.
Investigation of the high-temperature field distribution characteristics for a multi-jet burner by OH-PLIF and coherent anti-Stokes Raman spectroscopy
Authors: Bai Bing , Qi Xinhua , Yang Wenbin , Che Qingfeng , Sun Weimin , Li Bo , Chen Shuang 
Published: August 2023

Abstract
The construction of a high-temperature gas calibration source is of great significance since it can provide an effective high-temperature experimental environment for, e.g. verifying high-temperature measurement techniques and studying high-temperature combustion mechanisms. Here, we try to obtain a high-temperature gas field on a multi-jet burner by controlling the gas supplies to it. We use OH planar laser-induced fluorescence (OH-PLIF) to observe the compositional uniformity of the field and coherent anti-Stokes Raman scattering (CARS) to investigate the temperature uniformity of the field. We find from OH-PLIF images that the distribution of OH between the adjacent jets becomes more uniform with the increasing flow rate of CH4, and the flow rate of the co-flow N2 around jets also affects the uniformity of OH distribution. The measured temperature distribution by CARS is consistent with the OH distribution. At the jet outlet location, the temperature distribution had a periodic variation and gradually became more uniform with the height increased from the jet outlet. We find that the flow rate of CH4 and co-flow N2 and the radiative heat transfer rate play an important role in temperature distribution for the multi-jet burner. Also, the results show that a wide range of temperatures can be constructed by regulating the recipe of the gas supplies, and the highest temperature achieved in this work is 2457 K.
Engineering the defect distribution in ZnO nanorods through laser irradiation
Authors: Zheng Shuo , Chen Zuolong , Duley Walter W , Wu Yimin A , Peng Peng , Zhou Y Norman 
Published: August 2023

Abstract
In recent years, defect engineering has shown great potential to improve the properties of metal oxide nanomaterials for various applications thus received extensive investigations. While traditional techniques mostly focus on controlling the defects during the synthesis of the material, laser irradiation has emerged as a promising post-deposition technique to further modulate the properties of defects yet there is still limited information. In this article, defects such as oxygen vacancies are tailored in ZnO nanorods through nanosecond (ns) laser irradiation. The relation between laser parameters and the temperature rise in the ZnO due to laser heating was established based on the observation in the SEM and the simulation. Raman spectra indicated that the concentration of the oxygen vacancies in the ZnO is temperature-dependent and can be controlled by changing the laser fluence and exposure time. This is also supported by the absorption spectra and the photoluminescence spectra of ZnO NRs irradiated under these conditions. On the other hand, the distribution of the oxygen vacancies was studied by XPS depth profiling, and it was confirmed that the surface-to-bulk ratio of the oxygen vacancies can be modulated by varying the laser fluence and exposure time. Based on these results, four distinctive regimes containing different ratios of surface-to-bulk oxygen vacancies have been identified. Laser-processed ZnO nanorods were also used as the catalyst for the photocatalytic degradation of rhodamine B (RhB) dye to demonstrate the efficacy of this laser engineering technique.
On multifractal analysis and large deviations of singular hyperbolic attractors
Authors: Shi Yi , Tian Xueting , Varandas Paulo , Wang Xiaodong 
Published: August 2023

AbstractIn this paper we study the multifractal analysis and large derivations for singular hyperbolic attractors, including the geometric Lorenz attractors. For each singular hyperbolic homoclinic class whose periodic orbits are all homoclinically related and such that the space of ergodic probability measures is connected, we prove that: (i) level sets associated to continuous observables are dense in the homoclinic class and satisfy a variational principle; (ii) irregular sets are either empty or are Baire generic and carry full topological entropy. The assumptions are satisfied byC1-generic singular hyperbolic attractors andCr-generic geometric Lorenz attractors(r⩾2). Finally we prove level-2 large deviations bounds for weak Gibbs measures, which provide a large deviations principle in the special case of Gibbs measures. The main technique we apply is the horseshoe approximation property.
Compact sets with large projections and nowhere dense sumset
Authors: Balka Richárd , Elekes Márton , Kiss Viktor , Nagy Donát , Poór Márk 
Published: August 2023

Abstract
We answer a question of Banakh, Jabłońska and Jabłoński by showing that for

d
⩾
2

there exists a compact set

K
⊆

R

d

such that the projection of K onto each hyperplane is of non-empty interior, but K + K is nowhere dense. The proof relies on a random construction. A natural approach in the proofs is to construct such a K in the unit cube with full projections, that is, such that the projections of K agree with that of the unit cube. We investigate the generalization of these problems for projections onto various dimensional subspaces as well as for

ℓ

-fold sumsets. We obtain numerous positive and negative results, but also leave open many interesting cases. We also show that in most cases if we have a specific example of such a compact set then actually the generic (in the sense of Baire category) compact set in a suitably chosen space is also an example. Finally, utilizing a computer-aided construction, we show that the compact set in the plane with full projections and nowhere dense sumset can be self-similar.
Global existence and convergence results for a class of nonlinear time fractional diffusion equation
Authors: Huy Tuan Nguyen 
Published: August 2023

Abstract
This paper investigates Cauchy problems of nonlinear parabolic equation with a Caputo fractional derivative. When the initial datum is sufficiently small in some appropriate spaces, we demonstrate the existence in global time and uniqueness of a mild solution in fractional Sobolev spaces using some novel techniques. Under some suitable assumptions on the initial datum, we show that the mild solution of the time fractional parabolic equation converges to the mild solution of the classical problem when

α
→

1

−

. Under some appropriate assumptions on the initial datum, we show that the mild solution of the time fractional diffusion equation converges to the mild solution of the classical problem when

α
→

1

−

. Our theoretical results can be widely applied to many different equations such as the Hamilton–Jacobi equation, the Navier–Stokes equation in two cases: the fractional derivative and the classical derivative. Our paper also provides a completely new answer to the related open problem of convergence of solutions to fractional diffusion equations as the order of fractional derivative approaches 1−.
Uniform hyperbolicity of a class of scattering maps
Authors: Yoshino Hajime , Mertig Normann , Shudo Akira 
Published: August 2023

Abstract
In recent years fractal Weyl laws and related quantum eigenfunction hypothesis have been studied in a plethora of numerical model systems, called quantum maps. In some models studied there one can easily prove uniform hyperbolicity. Yet, a numerically sound method for computing quantum resonance states, did not exist. To address this challenge, we recently introduced a new class of quantum maps (Mertig and Shudo 2018 Phys. Rev. E 97 042216). For these quantum maps, we showed that, quantum resonance states can numerically be computed using theoretically grounded methods such as complex scaling or weak absorbing potentials (Mertig and Shudo 2018 Phys. Rev. E 97 042216). However, proving uniform hyperbolicty for this class of quantum maps was not straight forward. Going beyond that work this article generalises the class of scattering maps and provides mathematical proofs for their uniform hyperbolicity. In particular, we show that the suggested class of two-dimensional symplectic scattering maps satisfies the topological horseshoe condition and uniform hyperbolicity. In order to prove these properties, we follow the procedure developed in the paper by Devaney and Nitecki (1979 Commun. Math. Phys.
67 137–46). Specifically, uniform hyperbolicity is shown by identifying a proper region in which the non-wandering set satisfies a sufficient condition to have the so-called sector bundle or cone field. Since no quantum map is known where both a proof of uniform hyperbolicity and a methodologically sound method for numerically computing quantum resonance states exist simultaneously, the present result should be valuable to further test fractal Weyl laws and related topics such as chaotic eigenfunction hypothesis.
The time asymptotic expansion for the compressible Euler equations with time-dependent damping
Authors: Geng Shifeng , Huang Feimin , Jin Guanghui , Wu Xiaochun 
Published: August 2023

Abstract
For the compressible Euler equations with time-dependent damping

−

1

(
1
+
t

)

λ

ρ
u

, we propose a time asymptotic expansion around the self-similar solution of the generalized porous media equation and rigorously justify this expansion as

λ
∈
(

1
7

,
1
)

. Furthermore, the above expansion is the best asymptotic profile of the solution to the compressible Euler equations with time-dependent damping.
A discrete ordinates Boltzmann solver for application to inverse planning of photons and protons
Authors: Bedford James L 
Published: August 2023

Abstract
The aim of this work is to develop a discrete ordinates Boltzmann solver that can be used for calculation of absorbed dose from both photons and protons within an inverse planning optimiser, so as to perform accurate dose calculation throughout the whole of the inverse planning process. With photons, five transport sweeps were performed to obtain scattered photon fluence, and unscattered electron fluence was then obtained and used as a fixed source for solution of the electron transport equations. With protons, continuous slowing down was treated as a fixed source, and five transport sweeps were used to calculate scattered fluence. The total electron or proton fluence was multiplied by the stopping power ratio for the transport medium to obtain absorbed dose. The method was evaluated in homogeneous media and in a lung case where the planning target volume was surrounded by low-density lung material. Photon arc, proton passive scattering and proton arc treatments were considered. The results were compared to a clinically validated convolution dose calculation for photons, and with an analytical method for protons. In water-equivalent media, the discrete ordinates method agrees with the alternative algorithms to within 2%. Convergence is found to be sufficiently complete for water-, lung- and bone-equivalent materials after five iterations. The dose calculated by the relatively simple angular quadrature is seen to be very close to that calculated by a more comprehensive quadrature. For inhomogeneous lung plans, the method shows more heterogeneity of dose to the planning target volume than the comparative methods. The discrete ordinates Boltzmann solver provides a general framework for dose calculation with both photons and protons. The method is suitable for incorporation into an inverse planning optimiser, so that accurate dose calculation in a heterogeneous medium can be obtained throughout inverse planning, with the result that the final dose distribution is as predicted by the optimiser.
Variable stiffness mechanism of flexible composite laminates implanted with modular SMAHC
Authors: Pan Wencheng , Ke Jun , Hu Yan , Wu Zhenyu 
Published: August 2023

Abstract
In this study, a new flexible hybrid shape memory alloy composites (SMAHCs) with a polydimethylsiloxane (PDMS) matrix containing a shape memory alloy (SMA) of a hybrid Basalt/Kevlar fiber 3D woven composite is developed. The SMAHC is implanted into a glass fiber/PDMS composite laminate in a modular manner to study the stiffness of composite plates in response to temperature. The variable stiffness theory of the SMAHC is derived, and the influence of SMA parameters on the stiffness of the SMAHC is analyzed. A three-point bending test is performed to determine the stiffness of the composite plates at multiple temperature points in the form of Joule heat driving the composite plates. The stress and temperature distributions of the composite plate are analyzed in Abaqus under a temperature-displacement coupling setting. The results shows that the SMAHC stiffness is negatively correlated with SMA fiber diameter and positively correlated with SMA fiber volume fraction. With an increase in driving temperature, the stiffness of the composite plates tends to decrease. When the end temperature of the austenitic phase transformation is reached, the high-modulus austenitic SMA slightly increase the stiffness of the composite plate. The stiffness improvement is more significant when the SMAHC is placed in the middle area of the laminate and the SMA is located in the tension area. This study may provide a reference for the design of variable stiffness SMAHC for plate composite structures.