bluuebunny/crossref_metadata_2025_split huggingface dataset:
Influence of spontaneously generated coherence on absorption, dispersion, and group index in a five-level cascade atomic system
Authors: Mai Anh Le Nguyen , Bang Nguyen Huy , Van Phu Nguyen , Khoa Dinh Xuan , Thi Ngan Nguyen , Huyen Bui Thu , Doai Le Van 
Published: March 2023

Abstract
By solving the density matrix equations in the steady state, we have derived analytical expressions for the absorption, dispersion, and group index of a five-level cascade-type atomic system as functions of laser intensity and frequency, spontaneously generated coherence (SGC), and relative phase of applied fields. The influences of SGC and relative phase on absorption, dispersion, and group index of this system under electromagnetically induced transparency (EIT) are studied. It is shown that the three EIT windows of system become deeper and narrower as the strength of SGC increases. These lead to an increase in the slope and the amplitude of the dispersion curves at three EIT windows. As a result, the amplitude of the group index at these three EIT windows also becomes larger when the strength of SGC increases. In particular, the group index can easily be switched between negative and positive values i.e., the light propagation can easily be converted between superluminal to subluminal modes by adjusting the strength of SGC, relative phase or the coupling laser intensity.
Noether symmetries in f(T, TG) cosmology
Authors: Kadam S A , Mishra B , Levi Said Jackson 
Published: March 2023

AbstractAll degrees of freedom related to the torsion scalar can be explored by analysing, thef(T,TG) gravity formalism where,Tis a torsion scalar andTGis the teleparallel counterpart of the Gauss-Bonnet topological invariant term. The well-known Noether symmetry approach is a useful tool for selecting models that are motivated at a fundamental level and determining the exact solution to a given Lagrangian, hence we explore Noether symmetry approach inf(T,TG) gravity formalism with three different forms off(T,TG) and study how to establish nontrivial Noether vector form for each one of them. We extend the analysis made in S Capozziello, M De Laurentis, and K F Dialektopoulos 2016, “Noether symmetries in gauss–bonnet-teleparallel cosmology,”Eur. Phys. J. C76, 629. for the formf(T,TG)=b0TGk+t0Tmand discussed the symmetry for this model with linear teleparallel equivalent of the Gauss-Bonnet term, followed by the study of two models containing exponential form of the teleparallel equivalent of the Gauss-Bonnet term. We have shown that all three cases will allow us to obtain non-trivial Noether vector which will play an important role to obtain the exact solutions for the cosmological equations.
Estimation of electron temperature dynamics in warm dense gold using measured and DFT-calculated plasma frequency
Authors: Shikne Rakesh , Yoneda Hitoki , Chaurasia Shivanand 
Published: March 2023

Abstract
In this study, we report the temperature evolution of electron density of states (DOS) along with the thermophysical and optical properties of gold calculated by means of density functional theory (DFT). To corroborate the effects due to temperature-dependent electron density of states, we performed ellipsometric pump-probe experiments with broadband white-light continuum probe pulse that covered both the intraband and the interband region of the dielectric permittivity of gold. The intraband part was analyzed to give plasma frequency and collision rate as a function of the pump-probe delay. The electron temperature evolution of warm dense gold is determined by comparing the experimental plasma frequency dynamics with the DFT-calculations. The study also emphasizes the essential role of temperature-dependent modifications to the electron DOS and the thermophysical properties in order to model the non-equilibrium states of matter.
Quantum chaos and thermalization in the two-mode Dicke model
Authors: Kirkova Aleksandrina V , Ivanov Peter A 
Published: March 2023

Abstract
We discuss the onset of quantum chaos and thermalization in the two-mode Dicke model, which describes the dipolar interaction between an ensemble of spins and two bosonic modes. The two-mode Dicke model exhibits normal to superradiant quantum phase transition with spontaneous breaking either of a discrete or continuous symmetry. We study the behaviour of the fidelity out-of-time-order correlator (FOTOC) derived from the Loschmidt echo signal in the quantum phases of the model. We show that the exponential growth of the FOTOC in the beginning of the time evolution cannot be related to a classical unstable point in the general case. Furthermore, we find that the collective spin observable in the two-mode Dicke model quickly saturates to its long-time average value, and shows very good agreement between its diagonal ensemble average and microcanonical average even for a small number of spins. We show that the temporal fluctuations of the expectation value of the collective spin observable around its average are small and decrease with the effective system size, which leads to thermalization of the spin system.
Study of optoelectronic and thermoelectric properties of double perovskites X2HfI6 (X = Ga, In, Tl) for renewable energy
Authors: Kattan Nessrin A , Rouf Syed Awais , Mahmood Q , AL-Anazy Murefah Mana , Amin Mohammed A , Hegazy H H , Morsi Manal , Alotaibi Nouf H , Somaily H H 
Published: March 2023

Abstract
The double perovskites (DPs) are outstanding materials for renewable energy and other optoelectronic applications. Here in this paper, the thermoelectric and optical behavior of X2HfI6 (X = Ga, In, Tl) have been explained systematically by DFT. The structural stability has been certified using ionic radii in terms of tolerance factor, and dynamic stability has been confirmed by positive phonon dispersion frequencies in acoustic modes. The band structure findings show the direct band gaps for (Ga, In, Tl) based DPs. The optical properties have been investigated by dispersion, absorption, refection, and related other optical characteristics. The absorption bands are existing in ultraviolet region and shifted to higher energy (blue shift). The reflection and optical loss of light are noted less than 0.3 which increases their potential for optoelectronic devices. The high Seebeck coefficient and electrical conductivity along with ultralow lattice thermal conductivity confirm the high figure of merit at and below the room temperature.
Estimation of carbon dust particle lifetime in a radio-frequency thermal plasma
Authors: Long J M , Ou Jing , Huang Yueheng 
Published: March 2023

Abstract
A carbon dust particle in a collisionless thermal plasma is studied under the assumption of the drifting Maxwellian distribution with a time varying velocity caused by the oscillatory radio-frequency (RF) field. The dust particle potential decreases while its fluctuation increases with the increasing RF field strength or the decreasing frequency even taken into account the thermionic current. As the thermionic current is increased by changing the dust particle surface temperature, the resultant increasing dust particle potential can vary from negative to positive, and the fluctuation of the dust particle potential increases first and then decreases. When the dust particle heating and mass loss processes are considered, it is found that the fluctuation of the total energy flux to the dust particle is mainly determined by the electron energy flux, which causes the stair-like increase of the dust particle surface temperature in heating process and the stair-like decrease of the dust particle radius in the mass loss process. With the increasing RF field strength or decreasing frequency, the increase of the total energy flux to the dust particle leads to the decrease of the dust particle lifetime. The results mean that the presence of the RF field can shorten the dust particle lifetime or reduce the dust particle survivability in RF plasma, by compared with in the absence of the RF field.
Polyvinyl alcohol/polyacrylamide double-network hydrogel-based semi-dry electrodes for robust electroencephalography recording at hairy scalp for noninvasive brain–computer interfaces
Authors: Li Guangli , Liu Ying , Chen Yuwei , Li Mingzhe , Song Jian , Li Kanghua , Zhang Youmei , Hu Le , Qi Xiaoman , Wan Xuan , Liu Jun , He Quanguo , Zhou Haihan 
Published: March 2023

Abstract

Objective. Reliable and user-friendly electrodes can continuously and real-time capture the electroencephalography (EEG) signals, which is essential for real-life brain–computer interfaces (BCIs). This study develops a flexible, durable, and low-contact-impedance polyvinyl alcohol/polyacrylamide double-network hydrogel (PVA/PAM DNH)-based semi-dry electrode for robust EEG recording at hairy scalp. Approach. The PVA/PAM DNHs are developed using a cyclic freeze-thaw strategy and used as a saline reservoir for semi-dry electrodes. The PVA/PAM DNHs steadily deliver trace amounts of saline onto the scalp, enabling low and stable electrode-scalp impedance. The hydrogel also conforms well to the wet scalp, stabilizing the electrode-scalp interface. The feasibility of the real-life BCIs is validated by conducting four classic BCI paradigms on 16 participants. Main results. The results show that the PVA/PAM DNHs with 7.5 wt% PVA achieve a satisfactory trade-off between the saline load-unloading capacity and the compressive strength. The proposed semi-dry electrode exhibits a low contact impedance (18 ± 8.9 kΩ at 10 Hz), a small offset potential (0.46 mV), and negligible potential drift (1.5 ± 0.4 μV min−1). The temporal cross-correlation between the semi-dry and wet electrodes is 0.91, and the spectral coherence is higher than 0.90 at frequencies below 45 Hz. Furthermore, no significant differences are present in BCI classification accuracy between these two typical electrodes. Significance. Based on the durability, rapid setup, wear-comfort, and robust signals of the developed hydrogel, PVA/PAM DNH-based semi-dry electrodes are a promising alternative to wet electrodes in real-life BCIs.
Predictive JET current ramp-up modelling using QuaLiKiz-neural-network
Authors: Ho A. , Citrin J. , Challis C.D. , Bourdelle C. , Casson F.J. , Garcia J. , Hobirk J. , Kappatou A. , Keeling D.L. , King D.B. , Koechl F. , Lerche E. , Maggi C.F. , Mailloux J. 
Published: March 2023

Abstract
This work applies the coupled JINTRAC and QuaLiKiz-neural-network (QLKNN) model on the ohmic current ramp-up phase of a JET D discharge. The chosen scenario exhibits a hollow

T

e

profile attributed to core impurity accumulation, which is observed to worsen with the increasing fuel ion mass from D to T. A dynamic D simulation was validated, evolving j,

n

e

,

T

e

,

T

i

, n
Be, n
Ni, and n
W for 7.25 s along with self-consistent equilibrium calculations, and was consequently extended to simulate a pure T plasma in a predict-first exercise. The light impurity (Be) accounted for Z
eff while the heavy impurities (Ni, W) accounted for P
rad. This study reveals the role of transport on the

T

e

hollowing, which originates from the isotope effect on the electron-ion energy exchange affecting

T

i

. This exercise successfully affirmed isotopic trends from previous H experiments and provided engineering targets used to recreate the D q-profile in T experiments, demonstrating the potential of neural network surrogates for fast routine analysis and discharge design. However, discrepancies were found between the impurity transport behaviour of QuaLiKiz and QLKNN, which lead to notable

T

e

hollowing differences. Further investigation into the turbulent component of heavy impurity transport is recommended.
Testing a prediction model for the H-mode density pedestal against JET-ILW pedestals
Authors: Saarelma S. , Connor J.W. , Bilkova P. , Bohm P. , Field A.R. , Frassinetti L. , Fridstrom R. , Kirk A. 
Published: March 2023

Abstract
The neutral ionisation model proposed by Groebner et al (2002 Phys. Plasmas
9 2134) to determine the plasma density profile in the H-mode pedestal, is extended to include charge exchange processes in the pedestal stimulated by the ideas of Mahdavi et al (2003 Phys. Plasmas
10 3984). The model is then tested against JET H-mode pedestal data, both in a ‘standalone’ version using experimental temperature profiles and also by incorporating it in the Europed version of EPED. The model is able to predict the density pedestal over a wide range of conditions with good accuracy. It is also able to predict the experimentally observed isotope effect on the density pedestal that eludes simpler neutral ionization models.
Remote tropical central Pacific influence on driving sea surface temperature variability in the Northeast Pacific
Authors: Hong Hao-Jhe , Hsu Huang-Hsiung 
Published: March 2023

Abstract
The Northeast Pacific (NEP) had two record-breaking marine heatwave events in the winters of 2013–2015 and summer of 2019, which had a detrimental impact on the fisheries, marine ecosystems, and climate in North America. Here, we investigated the cause of sea surface temperature (SST) variability in NEP during late spring–summer of 1981–2020. The regression circulation anomalies to the principal component of leading empirical orthogonal function mode suggested that the warm NEP SST were characterized by a cyclonic circulation anomaly in the midlatitude North Pacific and a warming SST center in the Gulf of Alaska. We noted that this cyclonic circulation anomaly, attributable to a barotropic atmospheric wave originating from the tropical central Pacific (CP) in the preceding spring, reduced the surface heat flux loss from the ocean to the atmosphere in the NEP and led to the warm SST anomalies in summer. This finding was confirmed by not only empirical diagnosis but also long-term numerical simulations forced by the observed SST perturbations in the tropical CP. Our results highlight the role of the tropical CP SST in driving the summertime North Pacific SST variability through the atmospheric bridge in recent decades.
Equations of motion governing the dynamics of the exceptional points of parameterically dependent nonhermitian Hamiltonians
Authors: Šindelka Milan , Stránský Pavel , Cejnar Pavel 
Published: March 2023

Abstract
We study exceptional points (EPs) of a nonhermitian Hamiltonian

H
ˆ

(
λ
,
δ
)

whose parameters

λ
∈

C

and

δ
∈

R

. As the real control parameter δ is varied, the kth EP (or kth cluster of simultaneously existing EPs) of

H
ˆ

(
λ
,
δ
)

moves in the complex plane of λ along a continuous trajectory,

λ
k

(
δ
)

. Using an appropriate non-hermitian formalism (based upon the c-product and not upon the conventional Dirac product), we derive a self-contained set of equations of motion (EOM) for the trajectory

λ
k

(
δ
)

, while interpreting δ as the propagation time. Such EOM become of interest whenever one wishes to study the response of EPs to external perturbations or continuous parametric changes of the pertinent Hamiltonian. This is e.g. the case of EPs emanating from hermitian curve crossings/degeneracies (which turn into avoided crossings/near-degeneracies when the Hamiltonian parameters are continuously varied). The presented EOM for EPs have not only their theoretical merits, they possess also a substantial practical relevance. Namely, the just presented approach can be regarded even as an efficient numerical method, useful for generating EPs for a broad class of complex quantum systems encountered in atomic, nuclear and condensed matter physics. Performance of such a method is tested here numerically on a simple yet nontrivial toy model.
Nonlocal cubic and quintic nonlinear wave patterns in pure-quartic media
Authors: Tiofack Camus Gaston Latchio , Tabi Conrad Bertrand , Tagwo Hippolyte , Crépin Kofané Timoléon 
Published: March 2023

Abstract
In this work, pure-quartic soliton (PQS)formation is investigated in the framework of a nonlinear Schrödinger equation with competing Kerr (cubic) and non-Kerr (quintic) nonlocal nonlinearities and quartic dispersion. In the process, the modulational instability (MI) phenomenon is activated under a suitable balance between the nonlocal nonlinearities and the quartic dispersion, both for exponential and rectangular nonlocal nonlinear responses. Interestingly, the maximum MI growth rate and bandwidth are reduced or can completely be suppressed for some specific values of the cubic and quintic nonlocality parameters, depending on the type of nonlocal response. The analytical results are confirmed via direct numerical simulations, where the instability supports the signature of pure-quartic dark and bright solitons. These results may provide a better understanding of PQS structures for their potential applications in the next generation of nonlinear optical devices.
Deposition processing and surface metrology of MoNx thin films by design of experiment and single variable (nitrogen flow rate) methods
Authors: Chen Fong-Zhi , Ting I-Sheng , Kang Wei-Zen , Lin Yu-Wei , Huang Jia-Hong 
Published: March 2023

Abstract
In this study, the Taguchi design of experiment (DOE) was performed to optimize the deposition process of MoNx thin films using unbalanced magnetron sputtering (UBMS). Further single-variable experiments based on the sensitive parameter derived from the Taguchi experiments were conducted to investigate the effect of the parameter on the phase evolution, structure, and properties of the MoNx thin films. The MoNx thin films were deposited using DC-UBMS. Four controlling factors: N2 flow rate, substrate bias voltage, substrate temperature, and substrate rotational speed were selected in the Taguchi L9 matrix experiment. Electrical resistivity and hardness were chosen as the quality characteristics for the optimization. Analysis of variance (ANOVA) and analysis of mean (ANOM) were performed to identify the sensitive parameters and the optimum conditions. The confirmation test results for the optimizations of hardness (SH) and electrical resistivity (SR) were within the predicted ranges, and therefore the feasibility and reliability of the Taguchi optimization were verified. The results of ANOVA showed that nitrogen flow rate was the most sensitive factor. The optimum condition for the electrical resistivity was chosen to be the reference for the single-variable experiments, and nitrogen flow rate was selected as the controlling variable. The MoNx specimens in the single-variable experiment showed prevailing (200) texture that could be attributed to the lowest surface energy associated with (200) plane and the base metal steering effect by Mo (110). The results of single-variable experiments indicated that the retained Mo metal phase played an important role in hardness, electrical resistivity, and residual stress.
Low-voltage polymer transistors on hydrophobic dielectrics and surfaces
Authors: Kraft Ulrike , Nikolka Mark , Wang Ging‐Ji Nathan , Kim Yeongin , Pfattner Raphael , Alsufyani Maryam , McCulloch Iain , Murmann Boris , Bao Zhenan 
Published: March 2023

Abstract
A set of unique features, including large-area solution processing on flexible and stretchable substrates, make polymer semiconductors a promising material choice for a range of state-of-the-art applications in electronics, optoelectronics and sensing. Yet, an inherent weakness of polymer semiconductors remains their low dielectric constants, increasing their susceptibility toward unscreened dipoles. These dipoles are particularly prevalent at polymer-dielectric interfaces with high-k dielectrics, which are essential for the operation of devices such as low-voltage field-effect transistors. This shortcoming can be addressed by using self-assembled monolayers (SAMs) to passivate surfaces that impact charge transport. However, SAM-treatment also increases the hydrophobicity of surfaces and therefore poses a challenge for subsequent solution processing steps and complex packaging of devices. Here, we report low-voltage polymer transistors processed by spin coating of the polymer semiconductors on highly hydrophobic SAM-treated aluminum and hafnium oxide dielectrics (contact angles >100) through fine-tuning of the interfacial tension at the polymer-dielectric interface. This approach enables the processing and detailed characterization of near-amorphous (indacenodithiophene-cobenzothiadiazole) as well as semicrystalline (poly(2,5-bis(2-octyldodecyl)-3,6-di(thiophen-2-yl)diketopyrrolo[3,4-c]pyrrole-1,4-dione-alt-thieno[3,2-b]thiophen)) polymer semiconductors. We demonstrate polymer transistors that exhibit high on-currents and field-independent, charge carrier mobilities of 0.8 cm2 V−1s−1 at low operating voltages (<3 V).
Optimization and statistical modeling of the thermal conductivity of a pumice powder and carbonated coal particle hybrid reinforced aluminum metal matrix composite for brake disc application: a Taguchi approach
Authors: Ibrahim Tanimu Kogi , Yawas Danjuma Saleh , Danasabe Bashar , Adebisi Adetayo Abdulmumin 
Published: March 2023

Abstract
Aluminum metal matrix composites have been gaining traction in recent years due to their good mechanical properties and low weight. Particulate reinforcements for the improvement of its properties have been explored. This research aimed to determine the optimal composition of the reinforcement content (pumice powder and carbonated coal particles) and processing parameters (stirring speed, processing temperature, and stirring time) on the thermal conductivity of the developed material and also to characterize the constituents using x-ray fluorescence, x-ray diffraction, and scanning electron microscope/energy dispersive x-ray. The Taguchi optimization approach and regression analysis were used for the optimization and statistical analysis, respectively. The Taguchi optimization results gave an optimum thermal conductivity of 111.5, 112.5, 111.7, 112.9, and 112.4 W m−1 °C for pumice, carbonated coal, stirring speed, processing temperature, and stirring time respectively. The optimization also revealed the optimum setting for reinforcements and stir casting process factors as regards thermal conductivity to be 2.5%, 5.0%, 300 rpm, 850 °C, and 5 min for pumice powder, carbonated coal particles, stirring speed, temperature, and time, respectively. The optimal thermal conductivity of 120.40 W m−1 °C was obtained for the hybrid composite which gives a 131.54% improvement over the conventional grey cast iron brake disc. The particulate reinforcements (pumice powder and carbonated coal particles) and the processing factors all had significant effects on the thermal conductivity of the material, with the carbonated coal particles having the highest percentage contribution of 16.51%, as established by the analysis of variance. A model for predicting the thermal conductivity was developed using regression analysis, and high prediction accuracy was established with R-Square, R-Square (adj), and R-Square (pred) values of 94.68%, 88.60%, and 79.94%, respectively. The results of the characterization show the presence of hard compounds such as silica, iron oxide, and alumina in pumice powder and carbonated coal particles.