bluuebunny/crossref_metadata_2025_split huggingface dataset:
Enhanced total variation minimization for stable image reconstruction
Authors: An Congpei , Wu Hao-Ning , Yuan Xiaoming 
Published: May 2023

Abstract
The total variation (TV) regularization has phenomenally boosted various variational models for image processing tasks. We propose to combine the backward diffusion process in the earlier literature on image enhancement with the TV regularization, and show that the resulting enhanced TV minimization model is particularly effective for reducing the loss of contrast. The main purpose of this paper is to establish stable reconstruction guarantees for the enhanced TV model from noisy subsampled measurements with two sampling strategies, non-adaptive sampling for general linear measurements and variable-density sampling for Fourier measurements. In particular, under some weaker restricted isometry property conditions, the enhanced TV minimization model is shown to have tighter reconstruction error bounds than various TV-based models for the scenario where the level of noise is significant and the amount of measurements is limited. The advantages of the enhanced TV model are also numerically validated by preliminary experiments on the reconstruction of some synthetic, natural, and medical images.
Effects of electric polarization and defect energy levels induced by ion irradiation on the electrical behavior of 4H-SiC Schottky barrier diodes
Authors: Tian Yinan , Li Ronghua , Li Jian , Li Haixia , Zheng Xuefeng , Cheng Zhaoyi , Sun Jianrong 
Published: May 2023

Abstract
The effects of electric polarization and defect energy levels induced by C4+ irradiation on the electrical behavior of 4H-SiC Schottky barrier diodes (SBDs) are discussed. The parameters of the SBDs were extracted from capacitance–voltage (C–V) and current–voltage (I–V) measurements, the deep level transient spectroscopy (DLTS) was used to identify defect energy levels. In addition, the dielectric function and energy band structure of 4H-SiC were calculated using a first-principles approach to verify the enhancement of polarization and the origin of the defect energy levels. The results show that the net (donor) carrier concentration (N
d) increases with the increase of irradiation fluence, which is caused by the competition between irradiation-induced defects and the polarization effect. On the one hand, Z
1/2 is determined by DLTS. It is related to the doubly negatively (2-|0) charged state of V
c (carbon vacancy), which is a double acceptor. The intensity of the Z
1/2 peak increases with increasing irradiation fluence, which means that the defects caused by irradiation should reduce the N
d. On the other hand, the polarization effect does exist and it becomes stronger with the increase in the irradiation fluence, which makes the N
d increase. Obviously, the polarization effect induced by the irradiation is dominant for N
d when the depth of ion penetration is in the shallow layer behind the metal–semiconductor (M–S) interface. Irradiation induced electron traps and an uneven distribution of positively charged centers, which can cause ln(I)-V to exhibit a non-linear component before reaching the turn-on voltage. The series resistance (R
s), reverse current (I
R) increase and the forward current decreases with the increase in irradiation fluence. All these show that the irradiation causes degradation of Ni/4H-SiC SBD performance.
Boron nitride nanotube peapods at ultrasonic velocity impacts: a fully atomistic molecular dynamics investigation
Authors: De Sousa J M , Machado L D , Woellner C F , Medina M , Autreto P A S , Galvão D S 
Published: May 2023

Abstract
Boron nitride nanotube peapods (BNNT-peapod) are composed of linear chains of C60 molecules encapsulated inside BNNTs, they were first synthesized in 2003. In this work, we investigated the mechanical response and fracture dynamics of BNNT-peapods under ultrasonic velocity impacts (from 1 km s−1 up to 6 km s−1) against a solid target. We carried out fully atomistic reactive molecular dynamics simulations using a reactive force field. We have considered the case of horizontal and vertical shootings. Depending on the velocity values, we observed tube bending, tube fracture, and C60 ejection. Furthermore, the nanotube unzips for horizontal impacts at certain speeds, forming bi-layer nanoribbons ‘incrusted’ with C60 molecules. The methodology used here is applicable to other nanostructures. We hope it motivates other theoretical investigations on the behavior of nanostructures at ultrasonic velocity impacts and aid in interpreting future experimental results. It should be stressed that similar experiments and simulations were carried out on carbon nanotubes trying to obtain nanodiamonds. The present study expands these investigations to include BNNT.
Optical fiber Bragg grating based sensing system of flexible wearable smart sleeve for tracking human arm joint movements
Authors: Feng Yan , Wang Hao-xiang , Liu Peng-bin , Qi Hua , Pan Rui-zhi , Zhang Hong-pu , Zhang Hua 
Published: May 2023

Abstract
Optical fiber Bragg sensors (FBGs) have great potential in the field of flexible wearable devices for tracking human gestures. Due to different human sizes, different wearable tensions inevitably cause errors when tracking arm joint movements. We have designed a flexible wearable smart sleeve with four heads of FBG and spandex polyurethane fibers (SPFs). SPFs sewn with flexible fabric sleeves convert elbow yawing and wrist pitching and roll into an axial strain of FBG. The measuring system has been developed to deduce personalized sensitivity using a dynamic calibration method. For males and females, dynamic calibration, verification and tracking tests were carried out. From the male’s experimental data, the relative errors between the verification sensitivity and the personalized sensitivity are 1.93%, 5.85% and 7.16%, and the average relative errors between the tracking sensitivity and the personalized sensitivity are 7.09%, 5.58% and 2.52%, respectively. And from the data of the female’s experiment, the relative errors between the verification sensitivity and the personalized sensitivity are 0.25%, 5.0% and 6.75%, and the average relative errors between the tracking sensitivity and the personalized sensitivity are 0.99%, 5.56% and 6.95%, respectively. The experimental data have shown that this wearable smart sleeve and the measuring system work well. The research results can be used to develop FBG sensing systems for monitoring joint movements for different human sizes on-line.
State-of-the-art mental tasks classification based on electroencephalograms: a review
Authors: Saini M , Satija U 
Published: May 2023

Abstract
Electroencephalograms (EEGs) play an important role in analyzing different mental tasks and neurological disorders. Hence, they are a critical component for designing various applications, such as brain–computer interfaces, neurofeedback, etc. Mental task classification (MTC) is one of the research focuses in these applications. Therefore, numerous MTC techniques have been proposed in literary works. Although various literature reviews exist based on EEG signals for different neurological disorders and behavior analysis, there is a lack of reviews of state-of-the-art MTC techniques. Therefore, this paper presents a detailed review of MTC techniques, including the classification of mental tasks and mental workload. A brief description of EEGs along with their physiological and nonphysiological artifacts is also presented. Furthermore, we include information on several publicly available databases, features, classifiers, and performance metrics used in MTC studies. We implement and evaluate some of the commonly used existing MTC techniques in the presence of different artifacts and subjects, based on which the challenges and directions are highlighted for future research in MTC.
Surface defects in 4H-SiC: properties, characterizations and passivation schemes
Authors: Mao Weiwei , Cui Can , Xiong Huifan , Zhang Naifu , Liu Shuai , Dou Maofeng , Song Lihui , Yang Deren , Pi Xiaodong 
Published: May 2023

Abstract
Silicon carbide (SiC) is a typical wide band-gap semiconductor material that exhibits excellent physical properties such as high electron saturated drift velocity, high breakdown field, etc. The SiC material contains many polytypes, among which 4H-SiC is almost the most popular polytype as it possesses a suitable band-gap and high electron saturated drift velocity. In order to produce 4H-SiC power devices with a high barrier voltage of over several thousand volts, the minority carrier lifetime of 4H-SiC single crystals must be carefully managed. In general, both bulk defects and surface defects in 4H-SiC can reduce the minority carrier lifetime. Nevertheless, as surface defects have received less attention in publications, this study reviews surface defects in 4H-SiC. These defects can be classified into a number of categories, such as triangle defect, pit, carrot, etc. This paper discusses each one individually followed by the introduction of industrially feasible methods to characterize them. Following this, the impact of surface defects on the minority carrier lifetime is analyzed and discussed. Finally, a particular emphasis is put on discussing various passivation schemes and their effects on the minority carrier lifetime of 4H-SiC single crystals. Overall, this review paper aims to help young researchers comprehend surface defects in 4H-SiC single crystal material.
Cross-linked self-healing polymers containing rosin moiety based on dynamic urea and multiple hydrogen bonds
Authors: Lu Liwei , Yu Caili , Zhou Zhongqun , Zhang Faai 
Published: May 2023

Abstract
In recent years, the use of renewable biomass resources to prepare self-healing polymers has become a hot research topic because of the shortage of fossil resources. Herein, a novel type of rosin-based cross-linked polymer (PR) with dynamic urea and multiple hydrogen bonds is fabricated by copolymerizing a rosin ester with a dynamic crosslinking agent poly(urethane-urea) through a simple UV-initiated reaction. Owing to its robustly dynamic bonds, the resulting PR has both good mechanical properties and ideal self-healing ability. Specifically, the PR with 25.4% biomass rosin reaches a tensile strength of up to 4.1 MPa, an elongation at break of 112%, and stress self-healing efficiency of 91.3% at 80 °C for 24 h. Remarkably, the PR with a glass transition temperature above room temperature exhibits good shape memory behavior and excellent weldability (afford 2500 g after healing at 80 °C for 5 h). Finally, by surface platinum spraying and pre-stretching treatment, strain sensors based on microcracking mechanisms are realized.
Robust two-qubit gates using pulsed dynamical decoupling
Authors: Barthel Patrick , Huber Patrick H , Casanova Jorge , Arrazola Iñigo , Niroomand Dorna , Sriarunothai Theeraphot , Plenio Martin B , Wunderlich Christof 
Published: May 2023

Abstract
We present the experimental implementation of a two-qubit phase gate, using a radio frequency (RF) controlled trapped-ion quantum processor. The RF-driven gate is generated by a pulsed dynamical decoupling sequence applied to the ions’ carrier transitions only. It allows for a tunable phase shift with high-fidelity results. The conditional phase shift is measured using a Ramsey-type measurement with an inferred fringe contrast of up to

99

−
2

+
1

%

. We also prepare a Bell state using this laser-free gate. The phase gate is robust against common sources of error. We investigate the effect of the excitation of the center-of-mass (COM) mode, errors in the axial trap frequency, pulse area errors and errors in sequence timing. The contrast of the phase gate is not significantly reduced up to a COM mode excitation

<

20 phonons, trap frequency errors of +10%, and pulse area errors of −8%. The phase shift is not significantly affected up to

<

10 phonons and pulse area errors of −2%. Both, contrast and phase shift are robust to timing errors up to −30% and +15%. The gate implementation is resource efficient, since only a single driving field is required per ion. Furthermore, it holds the potential for fast gate speeds (gate times on the order of 100 µs) by using two axial motional modes of a two-ion crystal through improved setups.
Diagnosis of fast electron transport by coherent transition radiation
Authors: Liu Yangchun , Ning Xiaochuan , Wu Dong , Liang Tianyi , Liu Peng , Liu Shujun , Liu Xu , Sheng Zhengmao , Hong Wei , Gu Yuqiu , He Xiantu 
Published: May 2023

Abstract
Transport of fast electrons in overdense plasmas is of key importance in high energy density physics. However, it is challenging to diagnose the fast electron transport in experiments. In this article, we study coherent transition radiation (CTR) generated by fast electrons on the back surface of the target by using 2D and 3D first-principle particle-in-cell (PIC) simulations. In our simulations, aluminum targets of 2.7 g cc−1 are simulated in two different situations by using a newly developed high order implicit PIC code. Comparing realistic simulations containing collision and ionization effects, artificial simulations without taking collision and ionization effects into account significantly underestimate the energy loss of electron beams when transporting in the target, which fail to describe the complete characteristics of CTR produced by electron beams on the back surface of the target. Realistic simulations indicate the diameter of CTR increases when the thickness of the target is increased. This is attributed to synergetic energy losses of high flux fast electrons due to Ohm heating and colliding drags, which appear quite significant even when the thickness of the solid target only differs by micrometers. Especially, when the diagnosing position is fixed, we find that the intensity distribution of the CTR is also a function of time, with the diameter increased with time. As the diameter of CTR is related to the speed of electrons passing through the back surface of the target, our finding may be used as a new tool to diagnose the electron energy spectra near the surface of solid density plasmas.
Visually meaningful image encryption combining with reversible data hiding in encrypted images
Authors: Liu Zhaoyang , Xue Ru 
Published: May 2023

Abstract
At present, most image encryption schemes directly change plaintext images into ciphertext images without visual significance, such ciphertext images can be detected and therefore subject to various attacks. To protect the content security and visual safety of images, a visually meaningful image encryption (VMIE) algorithm combining with Reversible Data Hiding in Encrypted Images (RDHEI) is proposed. First, the secret image is encrypted and additional information is embedded by Chen hyperchaotic system and prediction error expansion (PEE) method. Then the source image is encrypted by a Lorentz hyperchaotic system. Finally, bit-xor operation is performed on the resulting encrypted image and the result is saved in a cloud database to generate an indexing key using SHA-256,which enables the receiver to recover the secret image with the resource image and the key alone. The scheme combines with the RDHEI, improving the transmission efficiency and has no image quality problems.The experimental results and security analysis show that the image encryption scheme has sufficient key space, strong key sensitivity and wide applicability.
Cosmic acceleration with bulk viscosity in an anisotropic f(R, L

m
) background
Authors: Solanki Raja , Patel Bina , Jaybhaye Lakhan V , Sahoo P K 
Published: May 2023

Abstract
In this article, we investigate the observed cosmic acceleration in the framework of a cosmological f(R, L

m
) model dominated by bulk viscous matter in an anisotropic background. We consider the locally rotationally symmetric Bianchi type I metric and derive the Friedmann equations that drive the gravitational interactions in f(R, L

m
) gravity. Further, we assume the functional form

f
(
R
,

L

m

)
=

R

2

+

L

m

α

, where α is a free model parameter, and then find the exact solutions of field equations corresponding to our viscous matter dominated model. We incorporate the updated H(z) data and the Pantheon data to acquire the best-fit values of parameters of our model by utilizing the χ
2 minimization technique along with the Markov Chain Monte Carlo random sampling method. Further, we present the behavior of physical parameters that describe the Universe’s evolution phase, such as density, effective pressure and EoS parameters, skewness parameter, and the statefinder diagnostic parameters. We find that the energy density indicates expected positive behavior, whereas the negative behavior of bulk viscous pressure contributes to the Universe’s expansion. The effective EoS parameter favors the accelerating phase of the Universe’s expansion. Moreover, the skewness parameter shows the anisotropic nature of spacetime during the entire evolution phase of the Universe. Finally, from the statefinder diagnostic test, we found that our cosmological f(R, L

m
) model lies in the quintessence region, and it behaves like a de-Sitter universe in the far future. We analyze different energy conditions in order to test the consistency of the obtained solution. We find that all energy conditions except strong energy condition (SEC) show positive behavior, while the violation of SEC favors the recently observed acceleration with the transition from decelerated to an accelerated epoch of the Universe’s expansion in the recent past.
Multiparametric non-linear TENS modulation to integrate intuitive sensory feedback
Authors: Bucciarelli Vittoria , Gozzi Noemi , Katic Natalija , Aiello Giovanna , Razzoli Margherita , Valle Giacomo , Raspopovic Stanisa 
Published: May 2023

Abstract

Objective. Transcutaneous electrical nerve stimulation (TENS) has been recently introduced in neurorehabilitation and neuroprosthetics as a promising, non-invasive sensory feedback restoration alternative to implantable neurostimulation. Yet, the adopted stimulation paradigms are typically based on single-parameter modulations (e.g. pulse amplitude (PA), pulse-width (PW) or pulse frequency (PF)). They elicit artificial sensations characterized by a low intensity resolution (e.g. few perceived levels), low naturalness and intuitiveness, hindering the acceptance of this technology. To address these issues, we designed novel multiparametric stimulation paradigms, featuring the simultaneous modulation of multiple parameters, and implemented them in real-time tests of performance when exploited as artificial sensory inputs. Approach. We initially investigated the contribution of PW and PF variations to the perceived sensation magnitude through discrimination tests. Then, we designed three multiparametric stimulation paradigms comparing them with a standard PW linear modulation in terms of evoked sensation naturalness and intensity. The most performant paradigms were then implemented in real-time in a Virtual Reality—TENS platform to assess their ability to provide intuitive somatosensory feedback in a functional task. Main results. Our study highlighted a strong negative correlation between perceived naturalness and intensity: less intense sensations are usually deemed as more similar to natural touch. In addition, we observed that PF and PW changes have a different weight on the perceived sensation intensity. As a result, we adapted the activation charge rate (ACR) equation, proposed for implantable neurostimulation to predict the perceived intensity while co-modulating the PF and charge per pulse, to TENS (ACRT). ACRT allowed to design different multiparametric TENS paradigms with the same absolute perceived intensity. Although not reported as more natural, the multiparametric paradigm, based on sinusoidal PF modulation, resulted being more intuitive and subconsciously integrated than the standard linear one. This allowed subjects to achieve a faster and more accurate functional performance. Significance. Our findings suggest that TENS-based, multiparametric neurostimulation, despite not consciously perceived naturally, can provide integrated and more intuitive somatosensory information, as functionally proved. This could be exploited to design novel encoding strategies able to improve the performance of non-invasive sensory feedback technologies.
Corrigendum: Model-based impurity emission front control using deuterium fueling and nitrogen seeding in TCV (2023 Nucl. Fusion 63 026006)
Authors: Koenders J.T.W. , Perek A. , Kool B. , Février O. , Ravensbergen T. , Galperti C. , Duval B.P. , Theiler C. , van Berkel M. , Team the TCV , MST1 Team the EUROfusion 
Published: May 2023

Abstract
In the published paper titled ‘Model-based impurity emission front control using deuterium fueling and nitrogen seeding in TCV’ (2023 Nucl. Fusion
63 026006), the legend of figure 5 shows the wrong colors: red and blue are switched. This corrigendum provides the correct legend for figure 5.
Particle pump-out induced by trapped electron mode turbulence in electron cyclotron heated plasmas on XuanLong-50 spherical torus
Authors: Wang Mingyuan , Li Jia , Bai Yukun , Dong Jiaqi , Shi Yuejiang , Zou Xiaolan , Liu Adi , Zhuang Ge , Li Hongyue , Li Songjian , Song Shaodong , Sun Tiantian , Liu Bing , Song Xianming , Liu Minsheng , Yuan Baoshan , Martin Peng Y.-K. 
Published: May 2023

Abstract
Particle pump-out effects induced by low-frequency (<200 kHz) density fluctuations were observed in solely electron cyclotron wave (ECW)-heated plasmas on the spherical torus XuanLong-50 (EXL-50) without a central solenoid. The intensity of the relative density fluctuations increases with increasing ECW power and decays when the ECW is turned off while sustaining the plasma current. The electron densities are maintained relatively high and steady when the density fluctuations are completely absent, indicating that the outward transport of electrons is dominated by the particle pump-out effect of the ECW. The density fluctuations are modulated by a supersonic molecular beam injection pulse and the modulation amplitude decreases with increasing electron density at the same ECW injection power and decreasing ECW power at the same electron density, respectively. Analysis revealed that a critical value of electron temperature gradient (ETG) triggers the density fluctuations, and the intensity of the relative density fluctuations is positively correlated with the ETG and approximately inversely proportional to the effective collision frequency. With plasma parameters similar to those of EXL-50 experiments, the HD7 code simulations demonstrate that trapped electron mode (TEM) turbulence can be excited by ETG higher than the critical value observed in the experiment. In addition, the dependence of the mode growth rate (supposed to be proportional to the saturation level of fluctuations in quasi-linear theory) and the measured intensity of the density fluctuations is comparable. The simulated outward particle flux integrated over the poloidal wave number spectrum is significant and proportional to ETG. These observations demonstrate that the density fluctuation is TEM turbulence, which is driven by ETG and induces particle pump-out when the electron density/effective electron collision frequency is low. The potential relevance of this work with the controls of plasma profiles, impurities, helium ash, and heat transport in future reactors of similar low effective collision frequency is also discussed.