bluuebunny/crossref_metadata_2025_split huggingface dataset:
Energy trapping to substitutional and charge compensation defects in persistent luminescent BaAl2O4:Tb3+
Authors: Jayaramu Shivaramu Nagarasanakote , Coetsee Elizabeth , Hölsä Jorma , Swart Hendrik C 
Published: October 2024

Abstract
The holistic approach of the photoluminescence (PL), thermoluminescence (TL), and persistent luminescence properties at room temperature of BaAl2O4:Tb3+ were investigated in detail using a wide range of techniques. Materials were obtained using a solution combustion synthesis. The x-ray powder diffraction patterns of nondoped and Tb3+ doped BaAl2O4 indicated the hexagonal phase, and a Tb4O7 solid solution was observed at 4 and 5 mol% Tb doped aluminate. X-ray photoelectron spectroscopy revealed that Ba occupied one site and that Tb ions occupied this site as Tb3+ as well as TbIV. PL emission in blue, green, and red was observed under an excitation at 228 nm, that originated from the interconfigurational 4f8–4f75d1 transitions of Tb3+. Time-of-flight secondary ion mass spectroscopy, UV–vis diffuse reflectance, and PL revealed the presence of a Cr3+ impurity. The 0.5 mol% Tb3+ doped BaAl2O4 exhibited a strong TL band at 354, 437 and 598 K, which were attributed to the traps formed by Tb3+ doping and subsequent O2− charge compensation. A persistent luminescence mechanism was constructed for the Tb3+ doped BaAl2O4. After the energy was stored in thermally liberated Tb3+ in the Ba2+ substitution sites and charge compensation defects, the Tb3+ was the source of the continuous luminescence.
A chaotic time series prediction model based on the improved dung beetle optimizer and echo state network
Authors: Wang Lei , Lun Shuxian , Li Ming , Lu Xiaodong 
Published: October 2024

Abstract
Echo state network (ESN) possesses advantages such as simple network structure, ease of training, and reliable prediction performance, making them widely applied in the field of time series prediction. Selecting the optimal reservoir parameters is a key issue in ESN research, as it determines the effectiveness of the network prediction, and it is crucial to design an efficient optimization method for parameter optimization. This paper introduces an improved version of the dung beetle optimizer (IDBO), which employs various strategies to enhance population initialization, algorithm optimization capability, and convergence speed. For theoretical function optimization problems, comparing IDBO with other commonly used optimization methods validated its effectiveness and feasibility. Subsequently, combining IDBO with ESN to construct a new model, IDBO-ESN, and conducting time series prediction experiments, the superior performance of this model is verified on two benchmark datasets and one real dataset.
Optimal quantum controls robust against detuning error
Authors: Kukita Shingo , Kiya Haruki , Kondo Yasushi 
Published: October 2024

Abstract
Precise control of quantum systems is one of the most important milestones for achieving practical quantum technologies, such as computation, sensing, and communication. Several factors deteriorate the control precision and thus their suppression is strongly demanded. One of the dominant factors is systematic errors, which are caused by discord between an expected parameter in control and its actual value. Error-robust control sequences, known as composite pulses, have been invented in the field of nuclear magnetic resonance (NMR). These sequences mainly focus on the suppression of errors in one-qubit control. The one-qubit control, which is the most fundamental in a wide range of quantum technologies, often suffers from detuning error. As there are many possible control sequences robust against the detuning error, it will practically be important to find ‘optimal’ robust controls with respect to several cost functions such as time required for operation, and pulse-area during the operation, which corresponds to the energy necessary for control. In this paper, we utilize the Pontryagin’s maximum principle (PMP), a tool for solving optimization problems under inequality constraints, to solve the time and pulse-area optimization problems. We analytically obtain pulse-area optimal controls robust against the detuning error. Moreover, we found that short-CORPSE, which is the shortest known composite pulse so far, is a probable candidate of the time optimal solution according to the PMP. We evaluate the performance of the pulse-area optimal robust control and the short-CORPSE, comparing with that of the direct operation.
Decoherence in electron transport: back-scattering, effect on interference and rectification
Authors: Soori Abhiram , Khanna Udit 
Published: October 2024

Abstract
Decoherence is an undesirable, but ubiquitous phenomenon in quantum systems. Here, we study the effect of partial decoherence, induced via a Büttiker probe, on two-terminal electronic transport across one-dimensional quantum wires and rings, in both the linear and non-linear regimes. We find that dephasing causes backscattering when introduced locally in a ballistic channel. Further, we find that decoherence results in rectification when inversion is broken in the two-terminal transport set-up by a combination of a local dephasing centre and a static impurity. Interestingly, the rectification strength and even its direction varies strongly with the relative distance between the probe and the scatterer. We further analyze how decoherence affects characteristic quantum effects in electronic transport, such as, Fabry-Pérot oscillations in double-barrier setups, and Aharonov–Bohm interference in one-dimensional rings, and find that the amplitude of oscillations in conductance is reduced by decoherence.
Multi-wing chaotic system based on meminductor and its application in image encryption
Authors: Ding Pengfei , Hu Weiwei , Geng Penghui , Yang Le 
Published: October 2024

Abstract
Meminductor is a novel type of nonlinear device following the memristor, characterized by its memory properties. Currently, research on meminductors is still in its infancy, with their physical devices yet to be formally realized. Therefore, conducting fundamental research on their nonlinear circuit properties and applications is of great significance. In this paper, a new multi-wing chaotic system is proposed based on the mathematical model of a magnetically controlled meminductor. By varying the values of its parameters, the system can generate two-wing, three-wing, and four-wing chaotic attractors. Various analytical methods are employed to study the dynamical behaviours of the proposed chaotic system. The results demonstrate that the system is highly sensitive to its initial conditions and control parameters, which makes it suitable for image encryption. Based on the new system, we propose a new algorithm for image encryption that combines the newly established four-dimensional multi-wing chaotic system with bit plane decomposition technique, firstly, the high four-bit planes containing 94% image information are disordered by S-type permutation, then the disordered bit planes perform operation of XOR with the random matrix generated by chaotic sequences, and finally, the encrypted image is obtained by merging the bit planes.
Complexation mechanism and adsorption modes of Cu (II) ions by wool keratin powder
Authors: Li Liang , Zeng Yuan , Ge Beibei , Liu Shuping , Liu Rangtong 
Published: October 2024

Abstract
The excessive presence of Cu (II) ions in wastewater has led to various health problems. Using wool keratin powder adsorbent, the adsorption of Cu (II) ions in wastewater was explored. The adsorption mechanism and efficiency of keratin powder towards Cu (II) ions were characterized by infrared spectroscopy, x-ray diffraction and scanning electron microscopy. The results indicate that the particle size of keratin powder has a significant impact on its adsorption performances. Keratin powder with smaller particle size has more adsorption sites, larger specific surface area, higher porosity and more effective adsorption capacity. After adsorption of Cu (II), the average diameter of keratin powder increased by 11.48 μm. The adsorption capacity reached 58.95 mg g−1, and the adsorption efficiency reached 99.52% after 12 h of contact time. The research results not only provide an effective solution for Cu (II) ion pollution in wastewater, but also explore the resource utilization of waste wool.
Finite element simulations of quartz crystal microbalances (QCM): from Sauerbrey to fractional viscoelasticity under water
Authors: Vélez-Cordero J Rodrigo , Jonguitud Flores Silvia , Yáñez Soto Bernardo 
Published: October 2024

Abstract
2D finite element simulations are performed on QCM working in the thickness-shear mode and loaded with different homogeneous films. They include a purely elastic film, a viscoelastic Maxwellian liquid, viscoelastic-Voigt solid, and the fractional viscoelastic (power-law) version of each case. Unlike single-relaxation kind models, fractional viscoelasticity considers the relaxation-time spectrum often found in polymeric materials. The films are tested in air or covered with liquids of different viscosities. Two substrate thicknesses are tested: 100 nm and 500 nm, the latter being close to the condition that promotes the resonance of the adsorbed film. In all cases the simulations are compared with small-load approximation theory (SLA). The 100 nm films follow the theory closely, although significant deviations of the SLA are observed as the overtone number n increases, even in purely elastic films. We also show that it is possible to identify the viscoelastic ‘fingerprint’ of the 100 nm films in air using raw data and Sauerbrey’s equivalent thickness obtained with the QCM in the 3 < n < 13 range. These numerical data are validated by experimental measurements of crosslinked polydimethylsiloxane films with thicknesses ∼150 nm. In contrast, the 500 nm films deviate notoriously from the SLA, for all viscoelastic models and overtones, with the largest deviation observed in the elastic film. When a liquid layer covers the QCM without an adsorbed film, the only overtone that numerically reproduces the theoretical value is the fundamental, n = 1. For n > 1, strong coupling between the solid and liquid is detected, and the original vibration modes of the crystal are altered by the presence of the liquid. Finally, the numerical simulations suggest that it is possible to detect whether a viscoelastic film is formed under a liquid layer using only the information from n = 1. In these film/liquid systems we also observe the so-called missing-mass effect, although the theory and simulations exhibit different levels of impact of such effect when the liquid viscosity is high.
The Hadamard condition on a Cauchy surface and the renormalized stress-energy tensor
Authors: Juárez-Aubry Benito A. , Kay Bernard S. , Miramontes Tonatiuh , Sudarsky Daniel 
Published: October 2024

Abstract
Given a Cauchy surface in a curved spacetime and a suitably defined quantum state on the CCR algebra of the Klein-Gordon quantum field on that surface, we show, by expanding the squared spacetime geodesic distance and the 'U' and 'V' Hadamard coefficients (and suitable derivatives thereof) in sufficiently accurate covariant Taylor expansions on the surface that the renormalized expectation value of the quantum stress-energy tensor on the surface is determined by the geometry of the surface and the first 4 time derivatives of the metric off the surface, in addition to the Cauchy data for the field's two-point function. This result has been anticipated in and is motivated by a previous investigation by the authors on the initial value problem in semiclassical gravity, for which the geometric initial data corresponds, a priori, to the spatial metric on the surface and up to 3 time derivatives off the surface, but where it was argued that the fourth derivative can be obtained with aid of the field equations on the initial surface.
Impact of the Epoch of Reionization sources on the 21-cm bispectrum
Authors: Noble Leon , Kamran Mohd , Majumdar Suman , Murmu Chandra Shekhar , Ghara Raghunath , Mellema Garrelt , Iliev Ilian T. , Pritchard Jonathan R. 
Published: October 2024

Abstract
The morphology of the 21-cm signal emitted by the neutral hydrogen present in the
intergalactic medium (IGM) during the Epoch of Reionization (EoR) depends both on the properties
of the sources of ionizing radiation and on the underlying physical processes within the
IGM. Variation in the morphology of the IGM 21-cm signal due to the different sources of the EoR
is expected to have a significant impact on the 21-cm bispectrum, which is one of the crucial
observable statistics that can evaluate the non-Gaussianity present in the signal and which can be
estimated from radio interferometric observations of the EoR. Here we present the 21-cm
bispectrum for different reionization scenarios assuming different simulated models for the
sources of reionization. We also demonstrate how well the 21-cm bispectrum can distinguish between
different IGM 21-cm signal morphologies, arising due to the differences in the reionization
scenarios, which will help us shed light on the nature of the sources of ionizing photons. Our
estimated large-scale bispectrum for all unique k-triangle shapes shows a significant difference
in the magnitude and sign across different reionization scenarios. Additionally, our focused
analysis of bispectrum for a few specific k-triangle shapes (e.g. squeezed-limit, linear, and
shapes in the vicinity of the squeezed-limit) shows that the large scale 21-cm bispectrum can
distinguish between reionization scenarios that show inside-out, outside-in and a combination of
inside-out and outside-in morphologies. These results highlight the potential of using the 21-cm
bispectrum for constraining different reionization scenarios.
Gravitational waves from collapse of pressureless matter in the early universe
Authors: Dalianis Ioannis , Kouvaris Chris 
Published: October 2024

Abstract
If an early matter phase of the Universe existed after inflation with the proper power spectrum, enhanced density perturbations can decouple from the Hubble flow, turn around and collapse. In contrast to
what happens in a radiation dominated Universe where pressure nullifies deviations from sphericity in these perturbations, in a matter dominated Universe, the lack of pressure although on the one hand facilitates the gravitational collapse, it allows small deviations from sphericity to grow substantially as the collapse takes place. The subsequent collapse is complicated: initially as non-spherical deviations grow, the collapsing cloud takes the form of a “Zel'dovich pancake”. After that, the more chaotic and nonlinear stage of violent relaxation begins where shells of the cloud cross and the matter is redistributed within a factor of a few of the free fall timescale, reaching a spherical virialized state. During the whole process, strong gravitational waves are emitted due to the anisotropy of the collapse and
the small time interval that the effect takes place. The emission of gravitational waves during the stage of the violent relaxation cannot be easily estimated with an analytical model. We perform an N-body simulation to capture the behaviour of matter during this stage in order to estimate the precise spectrum of gravitational waves produced in this scenario.
Explaining PTA results by metastable cosmic strings from SO(10) GUT
Authors: Antusch Stefan , Hinze Kevin , Saad Shaikh 
Published: October 2024

AbstractIn a recent paper (Phys. Rev. D108 (2023) 095053), we have demonstrated that the 2023 PTA results, which hint at a stochastic gravitational wave (GW) background at nanohertz frequencies, point towards a promising model-building route for realizing SO(10) Grand Unification with embedded inflation. The proposed supersymmetric scenario solves the doublet-triplet splitting without fine-tuning, accounts for charged fermion and neutrino masses, avoids conflicts with current proton decay bounds, and includes only representations no larger than the adjoint. It features multi-step breaking of SO(10) to the Standard Model gauge symmetry, with inflation embedded such that metastable cosmic strings are produced at the end of inflation. This cosmic string network generates a stochastic GW background that can explain the PTA results. In this paper, we provide a detailed analysis of the singled out GUT model class, focusing on how the gauge coupling unification condition affects the scales of multi-step SO(10) breaking and the preferred GW spectra. The lowest breaking scale, linked to inflation, the generation of right-handed neutrino masses for the seesaw mechanism, and metastable cosmic string production, coincides with the range suggested by the PTA results.
Induced gravitational waves: the effect of first order tensor perturbations
Authors: Picard Raphaël , Malik Karim A. 
Published: October 2024

Abstract
Scalar induced gravitational waves contribute to the cosmological gravitational wave background. They can be related to the primordial density power spectrum produced towards the end of inflation and therefore are a convenient new tool to constrain models of inflation. These waves are sourced by terms quadratic in perturbations and hence appear at second order in cosmological perturbation theory. While the focus of research so far was on purely scalar source terms we also study the effect of including first order tensor perturbations as an additional source. This gives rise to two additional source terms: a term quadratic in the tensor perturbations and a cross term involving mixed scalar and tensor perturbations. We present full analytical expressions for the spectral density of these new source terms and discuss their general behaviour. To illustrate the generation mechanism we study two toy models containing a peak on small scales. For these models we show that the scalar-tensor contribution becomes non-negligible compared to the scalar-scalar contribution on smaller scales. We also consider implications for future gravitational wave surveys.
Implications of neutrino species number and summed mass measurements in cosmological observations
Authors: Sasao N. , Yoshimura M. , Tanaka M. 
Published: October 2024

Abstract
We confront measurable neutrino degrees of freedom N
eff
and summed neutrino mass
in the early universe to particle physics at the energy scale
beyond the standard model (BSM),
in particular including the issue of neutrino mass type distinction.
The Majorana-type of massive neutrino is perfectly acceptable
by Planck observations, while the Dirac-type neutrino
may survive in a restricted class of models that suppresses
extra right-handed contribution to ΔN
eff = N
eff - 3
at a nearly indistinguishable level from the Majorana case.
There is a chance that
supersymmetry energy scale may be identified in
supersymmetric extension of left-right symmetric model
if improved N
eff measurements discover a finite value.
Combined analysis of this quantity with the summed neutrino mass
helps to determine the neutrino mass ordering pattern,
if measurement accuracy of order, 60 – 80 meV, is achieved,
as in CMB-S4.
Modelling study of divertor W leakage for different divertor conditions with Ne seeding in EAST tokamak
Authors: Xu Guoliang , Wang Hui , Ding Rui , Si Hang , Jia Guozhang , Guo Jin , Xie Hai , Yan Rong , Hai Ran , Zhu Dahuan , Chen Junling 
Published: October 2024

Abstract
Sequential SOLPS-ITER and DIVIMP simulations are carried out for tungsten (W) edge transport during neon (Ne) injection in EAST, elucidating the pathway of W impurity leakage from the divertor to the core plasma under different dissipative divertor conditions. Divertor conditions from low-recycling to detachment are generated by modulating the Ne injection rate in the SOLPS simulation. With the drift velocities incorporated in DIVIMP, W transport under the drift effect is investigated. For low-density L-mode plasma conditions with favorable B
t direction, the majority of W source originates from the outer divertor target and leaks upstream through the near-SOL E× B drift reversed region at both inner and outer divertors. The E× B drift is demonstrated to have a significant effect on W leakage and the effect diminishes with the increase of Ne injection rate. Compared to the D2 injection cases, Ne injection helps to achieve a strong dissipative divertor condition at a much lower plasma density, resulting in a higher W leakage ability due to the smaller friction with the background plasma. For Ne injection cases under high-density H-mode conditions, W leaks mostly through the outer divertor region while the inner divertor is fully detached. Compared to the L-mode cases, the shorter power decay lengths in the scrap-off layer (SOL) of the H-mode cases result in smaller parallel E× B drift velocities especially in the middle and far SOL region. With the increase of the Ne injection rate, the decrease of the E× B drift in the middle SOL leads to a wider near-separatrix W leakage path. Therefore, a worse divertor W screening is expected, which is consistent with the previous published experimental observations (Ding et al 2022 Nucl. Mater. Energy
33 101250).
The consequences of tritium mix for simulated ion cyclotron emission spectra from deuterium-tritium plasmas
Authors: Slade-Harajda T.W. , Chapman S.C. , Dendy R.O. 
Published: October 2024

Abstract
Measurements of ion cyclotron emission (ICE) are obtained from most large magnetically confined fusion plasma experiments, and may be used in future to quantify properties of the fusion-born alpha-particle population in deuterium-tritium (DT) plasmas in ITER. ICE is driven by spatially localised, strongly non-Maxwellian, minority energetic ion populations which relax collectively under the magnetoacoustic cyclotron instability. ICE spectral peaks are typically observed at, near, or separated by, integer harmonics of the energetic ion cyclotron frequency. Here, for the first time, we study how simulated ICE spectra from DT plasmas vary with tritium concentration and compare with an observed JET DT ICE spectrum. We incorporate a population of thermal tritons, in addition to thermal deuterons and an energetic minority population of fusion-born alpha-particles, in simulations with the kinetic particle-in-cell code EPOCH. This code has previously been used extensively for interpretation of ICE observations in terms of the self-consistent gyro-resolved collective Maxwell-Lorentz dynamics of tens of millions of simulation particles. Our simulation parameters are relevant to the ICE-generative outer midplane edge region of JET DT plasma 26 148, which included 11% tritium. Quantifying the variation of simulated ICE power spectra with tritium concentration reveals that our simulation with 11% tritium concentration most accurately represents the observed ICE spectrum from this plasma. This outcome is encouraging for the diagnostic application of ICE to fusion plasmas containing two thermal ion species, including future DT plasmas.