bluuebunny/crossref_metadata_2025 huggingface dataset:
The growth mechanism of PtS2 single crystal
Authors: Wang Huachao , Zhang Jisheng , Su Guowen , Lu Jiangwei , Wan Yanfen , Yu Xiaohua , Yang Peng
Published: April 2024

PtS2, a member of the group 10 transition metal dichalcogenides (TMDs), has received extensive attention because of its excellent electrical properties and air stability. However, there are few reports on the preparation of single-crystal PtS2 in the literature, and the growth mechanism of single crystal PtS2 is not well elucidated. In this work, we proposed a method of preparation that combines magnetron sputtering and chemical vapor transport to obtain monocrystalline PtS2 on a SiO2/Si substrate. By controlling the growth temperature and time, we have synthesized a single crystalline PtS2 of hexagonal shape and size of 1–2 μm on a silicon substrate. Combining the molecular dynamics simulation, the growth mechanism of single crystal PtS2 was investigated both experimentally and theoretically. The synthesis method has a short production cycle and low cost, which opens the door for the fabrication of other TMDs single crystals.
A high resolution reaction microscope with universal two-region time-focusing method
Authors: Gao Y. , Cao T. , Lin K. Z. , Guo D. L. , Zhang S. F. , Zhu X. L. , Zhang R. T. , Yan S. C. , Xu S. , Zhao D. M. , Ma X.
Published: April 2024

This paper presents a novel reaction microscope designed for ion–atom collision investigations, established at the Institute of Modern Physics, Chinese Academy of Sciences, Lanzhou, China. Its time-of-flight (TOF) spectrometer employs an innovative flight-time focusing method consisting of two acceleration regions, providing optimal time focusing conditions for charged fragments with diverse initial velocities. The TOF spectrometer’s axis intentionally tilts by 12° relative to the ion beam direction, preventing potential obstructions from the TOF grid electrodes. The introduced focusing method allows for a flexible time-focusing TOF spectrometer design without restricting the length ratio of the two regions. In addition, this configuration in our case significantly suppresses noise on the recoil ion detector produced by residual gas in the ion beam trajectory, which is a considerable challenge in longitudinal spectrometers. In a test experiment on the single electron capture reaction involving 62.5 keV/u He2+ ions and a helium atomic beam, the recoil longitudinal momentum resolution achieved 0.068 atomic units. This novel configuration and successful test run show excellent precision for ion–atom collision studies.
The Spanish Computer-Assisted Listening and Speaking Tutor
Authors: Martínez-Paricio Violeta , Koreman Jacques
Published: April 2024

This article presents the Spanish version of the Computer-Assisted Listening and Speaking Tutor (CALST), an online
platform that can be used to complement pronunciation training in the classroom. The Spanish CALST offers listening, speaking, and
spelling exercises for Northern-Central Peninsular Spanish as an L2. Exercises are tailored by an automatic comparison with the
learner’s native language based on a database of phonetically specified phoneme inventories for over 500 languages, with the
result that learners with different L1s are exposed to different exercises adapted to their specific needs. In this article, we
present a description of the exercises as well as the criteria used to develop Spanish content for CALST. We discuss the
limitations of the platform, the logging of user results as a partial solution to these limitations, and the possible future use
of the logged data to increase our understanding of L2 acquisition.
Analyzing warp drive spacetimes with Warp Factory
Authors: Helmerich Christopher , Fuchs Jared , Bobrick Alexey , Sellers Luke , Melcher Brandon , Martire Gianni
Published: April 2024

The field of warp research has been dominated by analytical methods to investigate potential solutions. However, these approaches often favor simple metric forms that facilitate analysis but ultimately limit the range of exploration of novel solutions. So far the proposed solutions have been unphysical, requiring energy condition violations and large energy requirements. To overcome the analytical limitations in warp research, we introduce Warp Factory: a numerical toolkit designed for modeling warp drive spacetimes. By leveraging numerical analysis, Warp Factory enables the examination of general warp drive geometries by evaluating the Einstein field equations and computing energy conditions. Furthermore, this comprehensive toolkit provides the determination of metric scalars and insightful visualizations in both 2D and 3D, offering a deeper understanding of metrics and their corresponding stress–energy tensors. The paper delves into the methodology employed by Warp Factory in evaluating the physicality of warp drive spacetimes and highlights its application in assessing commonly modeled warp drive metrics. By leveraging the capabilities of Warp Factory, we aim to further warp drive research and hopefully bring us closer to realizing physically achievable warp drives.
Designing spintronic devices in two-dimensional γ-graphyne: from ultrafast spin dynamics to logic applications
Authors: Xu(徐帅) Shuai , Xie(谢昊) Hao , Zhang(张一鸣) Yiming , Zhang(张宸榕) Chenrong , Jin(金蔚) Wei , Lefkidis Georgios , Hübner Wolfgang , Li(李春) Chun
Published: April 2024

The integration of two-dimensional materials into spintronics represents a frontier in the development of novel computational devices. In this work, by utilizing ab initio many-body theory, we investigate the spin dynamics within the Co-doped γ-graphyne structure, with a particular emphasis on the role of cobalt atoms as magnetic centers. The result reveals that each cobalt atom on the γ-graphyne hosts states with enough spin-density localization to facilitate both local spin flips and global spin transfers. The spin-dynamic processes in our study are characterized by ultrafast time scales and high fidelities, demonstrating efficient spin control in the system. Building upon these spin-dynamic processes, we theoretically construct a spin-based Reset-Set latch, thus demonstrating the feasibility of sophisticated logic operations in our system. Such spin-based devices exhibit the advantages of nano-spintronics over conventional-electronic approaches, offering lower energy consumption, faster operational speeds, and greater potential for miniaturization. The results highlight the efficacy of γ-graphyne nanoflakes doped with cobalt atoms as spin-information processing units, signifying a pivotal advancement in the incorporation of graphyne-based materials into sophisticated spintronic devices. This research paves the way for their application in areas such as data storage, quantum computing, and the development of complex logic-processing architectures.
Performance enhancement of 2D tin-halide perovskite transistors via molecule-assisted grain boundary passivation and hole doping
Authors: Le Zhikai , Liu Ao , Zhu Huihui
Published: April 2024

Tin (Sn2+)-based halide perovskites have garnered considerable interest for potential applications in field-effect transistors, owing to their low-cost solution processing capability and favorable hole transport properties. However, the polycrystalline nature of halide perovskite films necessitates efficient grain boundary passivation for reliable and stable device operation. Additionally, as a p-type semiconductor, controllable hole-doping is desired for modulating electrical properties. In this study, we demonstrate the dual functionality of doping the small molecule tetrafluoro-tetracyanoquinodimethane (F4TCNQ) into (C6H5C2H4NH3)2SnI4 (abbreviated as (PEA)2SnI4) through a cost-effective solution process. This doping introduces F4TCNQ as both a grain boundary passivator and a charge transfer p-dopant, resulting in effective improvements in transistor performance with a 6-fold enhancement in mobility, a substantial reduction in hysteresis, an enhanced current ratio, and improved stabilities.
Thermal conductivity of wrinkled graphene ring with defects
Authors: Ji Qingxiang , Li Bohan , Kadic Muamer , Wang Changguo
Published: April 2024

Graphene rings have great prospects in the fields of biological modulators, electrochemical biosensors, and resonators, but are prone to wrinkling which can affect their physical properties. This work establishes a theoretical model predicting the torsional wrinkling behavior of defective monolayer graphene rings, which provides direct understanding and reliable accuracy of the wrinkle levels. Then the thermal conductivity of wrinkled graphene rings is studied considering different wrinkle levels, defect concentrations and radii. It is found that with increased radius, defect concentration and torsional angle, the ratio of wrinkle amplitude to wavelength increases gradually. Vacancy defects and radii have more significant influences on the thermal conductivity than torsional wrinkles. The main influence mechanism of wrinkles and defects on thermal conductivity is revealed by phonon density of state. This work provides theoretical guidance for thermal manipulation based on the wrinkle-tuning approach.
Multi-beam coherent Fourier scatterometry
Authors: Soman S , Horsten R C , Scholte T , Pereira S F
Published: April 2024

Inspection of surface and nanostructure imperfections play an important role in high-throughput manufacturing across various industries. This paper introduces a novel, parallelised version of the metrology and inspection technique: Coherent Fourier scatterometry (CFS). The proposed strategy employs parallelisation with multiple probes, facilitated by a diffraction grating generating multiple optical beams and detection using an array of split detectors. The article details the optical setup, design considerations, and presents results, including independent detection verification, calibration curves for different beams, and a data stitching process for composite scans. The study concludes with discussions on the system’s limitations and potential avenues for future development, emphasizing the significance of enhancing scanning speed for the widespread adoption of CFS as a commercial metrology tool.
A novel cross-domain adaption network based on Se-Sk-DenseNet for remaining useful life prediction of rolling bearings under different working conditions
Authors: Guo Baosu , Li Hang , Dong Hao , Han Tianjie , Sun Yingbing , Hou Jianchang , Jiang Zhangpeng , Ni Qing
Published: April 2024

Effectively predicting the remaining useful life (RUL) of rolling bearings can ensure reliability and safety, minimize machine downtime, and reduce the operation and maintenance costs of enterprises. To solve the problems of data distribution discrepancy caused by different working conditions and the collected signals containing a lot of useless information and noise, a novel cross-domain adaption network (CDAN) is proposed in this study. Firstly, a novel feature extractor, squeeze-and-excitation (Se)-selective kernel (Sk)-DenseNet, is developed to extract useful critical features from the input data and remove the ineffective features by embedding Se and Sk attention blocks; besides, a new objective loss function consist of the RUL loss, the multi-kernel maximum mean discrepancy loss, the contrastive loss, and the Kullback–Leibler divergence loss, is proposed to solve the problem of data distribution shift; finally, the effectiveness and superiority of CDAN are proved on the PHM2012 bearings dataset. The results demonstrate that CDAN can extract deep critical features and achieve the high cross-domain RUL prediction accuracy under different working conditions.
An adaptive threshold-selected symplectic geometry mode decomposition for application to multi-modulation complex fault signals
Authors: Lv Zhe , Li Congming , Xiong Xiaoyan , Wang Xiangrong , Song Wei , Wu Bing
Published: April 2024

The signals obtained from complex mechanical systems are characterized by multilevel modulation and strong noise, which can lead to difficulties in fault feature extraction. Symplectic geometry mode decomposition (SGMD) proves to be a valid approach for decomposing signals. However, inaccurate threshold selection in the iterative decomposition process can compromise the quality of fault diagnosis results. To address the shortcomings of SGMD, this paper proposes adaptive SGMD with adaptive threshold selection for fault diagnosis. Based on minimum dispersion entropy indicators, correlation coefficient and stopping thresholds are adaptively chosen using the proposed enhanced dung beetle optimizer algorithm. Then the optimal symplectic geometry component (SGC) is filtered based on the value of the integrated indicators after decomposition. Finally, the optimal SGC is analyzed by envelope demodulation to extract gear fault information. Through simulation and experimental analysis, this method surpasses SGMD and other signal decomposition methods in the aspect of fault feature extraction and noise robustness. Additionally, the results indicate an increase in feature energy ratio by 2.14%–9.85% compared to SGMD. The paper demonstrates that the proposed method extracts the fault feature frequencies of gears more effectively in complex mechanical systems.
A novel subdomain adaptive intelligent fault diagnosis method based on multiscale adaptive residual networks
Authors: Wang Jinrui , Lv Xingwang , Xu Yufeng , Wan Yanbin , Bao Huaiqian , Han Baokun , Zhang Zongzhen
Published: April 2024

Traditional fault diagnosis methods may not capture key information during feature extraction due to the large distribution difference under different working conditions, which can result in poor accuracy of the diagnostic model. To address this issue, a subdomain adaptive bearing fault identification method guided by the local maximal mean difference (LMMD) under the multiscale adaptive residual network is proposed in this paper. The bearing vibration signals are preprocessed by wavelet convolution and wide convolution to generate initial features. Then, the multi-scale adaptive residual network is used to adjust the feature weights of different scales and extract richer feature information. To reduce the intra-class distribution difference, the LMMD is employed. Additionally, local interclass maximum mean difference (LIMMD) is used to increase the inter-class difference, preventing misclassification of samples from different classes due to their close proximity and achieving sub-domain distribution alignment. The fault diagnosis performance of the domain distance metric model guided by LMMD and LIMMD under the multiscale adaptive residual network is verified through two different bearing model validation experiments.
Atomistic simulation of the influence of semi-coherent interfaces in the V/Fe bilayer system on plastic deformation during nanoindentation
Authors: Hamdani Soumia , Abdeslam Saad , Hartmaier Alexander , Janisch Rebecca
Published: April 2024

Semi-coherent interfaces can have a strong influence on the mechanical behavior of bilayer systems, which is seen very clearly under indentation conditions where a well-defined plastic zone interacts directly with the interface. The main aim of this work is to study the influence of a semi-coherent bcc/bcc interface in the V/Fe bilayer system with molecular dynamics (MD) simulations. In particular, the influence of the V layer thicknesses on the apparent hardness of bilayer system is investigated. Our results show that the deformation behavior of pure V and pure Fe resulting from the MD simulations is in good agreement with the literature. Moreover, the MD simulations reveal a significant enhancement of the hardness of V/Fe bilayer system for thinner vanadium layers, resulting from the crucial role of the semi-coherent interface as a barrier to dislocation propagation. This is seen from a detailed analysis of the interaction of mobile dislocations in the plastic zone with misfit dislocations in the interface. Our work shows that dislocation pile-ups at the interface and formation of horizontal shear loops are two key mechanisms dominating the rate and magnitude of plastic deformation and thus contributes to our understanding of mechanical behavior of bilayer systems with semi-coherent interfaces.
Building a cm2 scale CVD graphene-based gas sensor: modelling the kinetic with a three-site adsorption/desorption Langmuir model
Authors: Malesys V , Andrieux-Ledier A , Lavenus P , Simon L
Published: April 2024

In this article, we aim to develop and study a highly sensitive and selective cm2 scale graphene-based gas sensor. We present the technology used to fabricate sensors which integrate monolayer chemical vapour deposition graphene: photolithography and transfer of layers. Characterization techniques (optical microscopy, AFM, micro-Raman spectroscopy, transport electrical measurements) ensure a diagnosis of graphene ribbons and allow good reproducibility of technological processes. We present the results of gas characterizations after a 200 ppm NO2 exposure. We propose a novel approach for the modelling of the sensor response with a three-site adsorption/desorption Langmuir model. This innovative way of modelling the sensor response should provide a better understanding of the sensor’s kinetic and help to overcome the long response time observed with graphene gas sensors.
Gate-bias stability of triple-gated feedback field-effect transistors with silicon nanosheet channels
Authors: Heo Hyojoo , Shin Yunwoo , Son Jaemin , Ryu Seungho , Cho Kyoungah , Kim Sangsig
Published: April 2024

In this study, we investigate the gate-bias stability of triple-gated feedback field-effect transistors (FBFETs) with Si nanosheet channels. The subthreshold swing (SS) of FBFETs increases from 0.3 mV dec−1 to 60 and 80 mV dec−1 in p- and n-channel modes, respectively, when a positive bias stress (PBS) is applied for 1000 s. In contrast, the SS value does not change even after a negative bias stress (NBS) is applied for 1000 s. The difference in the switching characteristics under PBS and NBS is attributed to the ability of the interface traps to readily gain electrons from the inversion layer. The switching characteristics deteriorated by PBS are completely recovered after annealing at 300 °C for 10 min, and the characteristics remain stable even after PBS is applied again for 1000 s.
Quasi-static crashworthiness behaviour of auxetic tubular structures based on rotating deformation mechanism
Authors: Solak Kemal , Orhan Suleyman Nazif
Published: April 2024

Auxetic materials have attracted significant interest due to their exceptional mechanical characteristics and distinctive deformation modes. Nevertheless, the practical use of these materials in engineering is constrained by their limited ability to absorb energy. Thus, enhancing the energy absorption (EA) capabilities of auxetic materials is crucial to expand their range of potential applications. In this study, the EA capabilities of auxetic tubular structures with rotating deformation mechanisms are examined, with a specific emphasis on three different perforation shapes: elliptic, peanut, and square, along with their modified versions incorporating stiffeners. The study employs a combination of experimental testing and numerical modelling, utilising ANSYS/LS-DYNA to evaluate various crashworthiness parameters. These parameters include total EA, specific EA, maximum crushing force, and crushing force efficiency, all of which are assessed under quasi-static compression conditions. The research highlights the importance of perforation shape and stiffener incorporation in enhancing crashworthiness. Results show that elliptic perforations exhibit superior EA and stiffened auxetic models outperform conventional ones in terms of crash absorber performance. The presence of stiffeners significantly improves the ability of tubular structures to withstand crushing forces. Furthermore, the study validates the numerical model against experimental findings, demonstrating a high level of agreement in terms of crushing force–displacement, EA, and failure modes. The research provides valuable insights into the design and performance of crashworthy structures and offers potential applications in various fields where impact resistance and EA are critical.
Third order nonlinear correlation of the electromagnetic vacuum at near-infrared frequencies
Authors: Settembrini Francesca Fabiana , Herter Alexa , Faist Jérôme
Published: April 2024

In recent years, electro-optic sampling, which is based on Pockel’s effect between an electromagnetic mode and a copropagating, phase-matched ultrashort probe, has been largely used for the investigation of broadband quantum states of light, especially in the mid-infrared and terahertz frequency range. The use of two mutually delayed femtosecond pulses at near-infrared frequencies allows the measurement of quantum electromagnetic radiation in different space-time points. Their correlation allows therefore direct access to the spectral content of a broadband quantum state at terahertz frequencies after Fourier transformation. In this work, we will prove experimentally and theoretically that when using strongly focused coherent ultrashort probes, the electro-optic sampling technique can be affected by the presence of a third-order nonlinear mixing of the probes’ electric field at near-infrared frequencies. Moreover, we will show that these third-order nonlinear phenomena can also influence correlation measurements of the quantum electromagnetic radiation. We will prove that the four-wave mixing of the coherent probes’ electric field with their own electromagnetic vacuum at near-infrared frequencies results in the generation of a higher-order nonlinear correlation term. The latter will be characterized experimentally, proving its local nature requiring the physical overlap of the two probes. The parameters regime where higher order nonlinear correlation results predominant with respect to electro-optic correlation of terahertz radiation is provided.
Multifunctional topological photonic crystal device for multichannel frequency routing and highly sensitive refractive index sensing
Authors: AbdelAll Naglaa , Almokhtar Mohamed , Khouqeer Ghada , Esmail Mohamed Saleh M , Abood Israa , El Soliman Sayed
Published: April 2024

We propose a novel photonic crystal (PC) structure with C-4 symmetry of the square lattice that utilizes topological edge states (TESs) to achieve multichannel frequency routing and high-sensitivity refractive index (RI) sensing. The proposed system combines trivial and nontrivial unit cells to form a unique lattice arrangement that supports multiple TESs. These states enable the realization of seven distinct output ports, each capable of transmitting a specific frequency, significantly enhancing optical communication systems’ bandwidth and data transfer capabilities. This feature makes the proposed PC structure an ideal candidate for multichannel frequency routing applications. Additionally, the structure incorporates a central cavity that exhibits robust light localization, making it highly sensitive to changes in the surrounding medium’s refractive index. Simulations demonstrate that the proposed structure can achieve RI sensing sensitivity of up to 721 nm/RIU, coupled with a high-quality factor exceeding

10

5

.

With its exceptional RI sensing capabilities, the proposed multichannel PC device holds immense potential for various technological advancements in frequency routing.
Perturbative and semi-analytical solutions to Teukolsky equations for massive fermions
Authors: Villani Mattia
Published: April 2024

In this work, we aim at solving the Teukolsky equations for a fermion with mass m

e
≠ 0 in the presence of a rotating black hole with mass M. We consider two different regimes:

m

˜

e

=

M

−
1

m

e

≪
1

and a
ω ≪ 1;

m

˜

e

≪
1

and a
ω ≳ 1. We treat each of these two regimes in different ways: we use a perturbative approach for the first, similar to the usual one employed for spin 0, 1, 2 and mass-less 1/2 fields, but with two small parameters (aω and

m

˜

e

); as we shall see, the second can be treated with a semi-analytical approach. In a forthcoming paper we shall study the remaining two cases in which

m

˜

e

≳
1

, while a
ω ≪ 1 or a
ω ≳ 1. The regime with

m

˜

e

≪
1

, but a
ω ≳ 1 is probably the most interesting from the astrophysics point of view, but this last two cases might be of some interest for the study of the interaction of fermions with very small black holes, which may be formed, for example, in the last stages of the Hawking evaporation.
What should we understand by the four-momentum of physical system?
Authors: Fedosin Sergey G
Published: April 2024

It is shown that, in general, in curved spacetime, none of the known definitions of four-momentum correspond to the definition, in which all the system’s particles and fields, including fields outside matter, make an explicit contribution to the four-momentum. This drawback can be eliminated under the assumption that the primary representation of four-momentum is the sum of two nonlocal four-vectors of the integral type with covariant indices. The first of these four-vectors is the generalized four-momentum, found with the help of Lagrangian density. The time component of the generalized four-momentum, in theory of vector fields, is proportional to the particles’ energy in scalar field potentials, and the space component is related to vector field potentials. The second four-vector is the four-momentum of fields themselves, and its time component is related to the energy given by tensor invariants. As a result, the system’s four-momentum is defined as a four-vector with a covariant index. The standard approach makes it possible to find the four-momentum in covariant form only for a free point particle. In contrast, the obtained formulas for calculating the four-momentum components are applied to a stationary and moving relativistic uniform system, consisting of many particles. In this case, the main fields of the system under consideration are taken into account, including the electromagnetic and gravitational fields, the acceleration field and the pressure field. All these fields are considered vector fields, which makes it possible to unambiguously determine the equations of motion of the fields themselves and the equations of motion of matter in these fields. The formalism used includes the principle of least action, charged and neutral four-currents, corresponding four-potentials and field tensors, which ensures unification and the possibility of combining fields into a single interaction. Within the framework of the special theory of relativity, it is shown that due to motion, the four-momentum of the system increases in proportion to the Lorentz factor of the system’s center of momentum, while in the matter of the system the sum of the energies of all fields is equal to zero. The calculation of the integral vector’s components in the relativistic uniform system shows that the so-called integral vector is not equal to four-momentum and is not a four-vector at all, although it is conserved in a closed system. Thus, in the theory of relativistic vector fields, the four-momentum cannot be found with the help of an integral vector and components of the system’s stress-energy tensor, in contrast to how it is assumed in the general theory of relativity.
On the dispersionless Davey-Stewartson hierarchy: the tau function, the Riemann-Hilbert problem and the Hamilton-Jacobi theory
Authors: Yi Ge , Hu Rong , Tian Kelei , Xu Ying
Published: April 2024

The dDS (dispersionless Davey-Stewartson) hierarchy is constructed by two eigenfunctions of a special Hamiltonian vector field. This hierarchy consists of the infinite symmetries of the dDS system. Further, this paper explores the tau function, the Riemann-Hilbert problem and Hamilton-Jacobi theory related to dDS hierarchy.
Evaluation of shielding properties of a developed nanocomposite from intercalated attapulgite clay by Cd/Pb oxides nanoparticles
Authors: Negm Hani H , El-Sharkawy Rehab M , Abdeltwab Eslam , Mostafa Massaud , Mahmoud Mohamed E , El-Taher Atef
Published: April 2024

The study investigated new nanocomposites’ γ-ray and neutron shielding properties based on raw attapulgite, a clay matrix intercalated with different weight percentages of mixed nano metal oxides CdO and PbO. The various percentages were as follows: (100–2x)% Attapulgite + x%CdO + x%PbO, abbreviated as (AT100–2x
CdxPb
x
), where x = 5, 10, 15%. The nanocomposites were characterized using XRD, FTIR, and EDX, confirming their successful preparation. SEM images revealed that the mixed oxide nanoparticles were successfully intercalated into the layers of attapulgite clay, with an average particle size of approximately 31.46 nm. The bulk densities of the prepared nanocomposites were measured to be in the range of 2.034 to 2.555 g/cm3. GEANT4 simulations were employed to evaluate the nanocomposites’ γ-ray and neutron shielding performance in the photon energy range of 0.015 to 15 MeV. Phys-X code was used for verification. The simulation results showed a maximum difference of approximately 9.5% between GEANT4 and Phys-X predictions. To assess the γ-ray shielding performance, various shielding parameters were calculated at selected photon energies. The μ

m
values ranged from 4.589 to 0.020 cm2.g−1, 6.311 to 0.021 cm2.g−1, 8.350 to 0.022 cm2.g−1 and 10.804 to 0.023 cm2.g−1 for raw attapulgite, AT90Pb5Cd5, AT80Pb10Cd10, AT70Pb15Cd15 across the photon energy range. The AT70Pb15Cd15 nanocomposite exhibited the highest μ

m
, Z

eff
, Z

eq
, and the lowest T
1/2, T
1/10, and MFP values. Notably, it also demonstrated the highest FNRCS (approximately 0.1 cm−1). These findings suggest that clay-based nanocomposites represent a new class of low-cost, locally available advanced materials with potential applications in γ-ray and neutron shielding characteristics.
A novel entanglement functions-based 4D fractional-order chaotic system and its bifurcation analysis
Authors: Tang Xiaoyue , Li Ruihong , Huang Dongmei
Published: April 2024

A novel 4D fractional-order chaotic entanglement system based on sinusoidal functions is established in this paper. We aim to reveal the relationship between the dynamical behavior of the new system and its entanglement coefficients. It is found that the equilibrium point of the system varies regularly with the successive change of the entanglement coefficient. The supercritical pitchfork bifurcation phenomenon of the new system is discussed based on the fractional-order stability theory. Furthermore, sufficient conditions and threshold for supercritical Hopf bifurcation caused by the entanglement coefficient are provided. Finally, the route to chaos of the new system is explored utilizing multiple numerical indicators, such as spectral entropy complexity, bifurcation diagrams, Lyapunov exponential spectrum, phase portraits, and 0–1 test curves. The results indicate that in addition to various chaotic attractors, there are phenomena such as period-doubling bifurcations, period windows, and coexisting symmetric attractors (periodic or chaotic).
Effect of porosity on deuterium retention in titanium thin film
Authors: Das Basanta Kumar , Das Rashmita , Prathap C , Verma Rishi , Sharma Archana
Published: April 2024

The absorption process of deuterium in titanium was studied in titanium film produced in two different types of copper substrate, one was a polished copper substrate and the other one was chemically etched copper substrate. Titanium film was produced by thermal evaporation method. It was activated at a temperature of 500 °C followed by deuteration at room temperature. Titanium film was characterized by XRD for crystallographic information, SEM for surface morphology, RGA for deuterium desorption studies and weight measurement for D/Ti ratio. The difference in porosity of both the samples is confirmed from XRD analysis and SEM images. Different diffusion process is observed in two different substrates from the RGA spectra. Presence of multiple trap sites in the thin film of both the substrates is observed from the RGA spectra. From the weight measurement, D/Ti ratio in polished substrate is found to be 1.03 whereas in case of chemically etched substrate it is 1.54.
Substrate temperature dependent crystal structure and deep-ultraviolet photodetection of ZnGa2O4 thin films
*
Authors: Liu Jia-Hang , Li Lei , Zhang Fan , Qi Ya-Ping , Wu Zhen-Ping , Tang Wei-Hua
Published: April 2024

Zinc gallate (ZnGa2O4) is a promising material for deep-ultraviolet (DUV) photodetectors, owing to its wide bandgap and high transparency. However, the effect of substrate temperature on the structural and optical properties of ZnGa2O4 thin films prepared by magnetron sputtering is not well understood. Here, we report a systematic study of the influence of substrate temperature on the crystal quality, stoichiometry, bandgap, and photodetection performance of ZnGa2O4 thin films deposited on sapphire substrates. We find that the films undergo a phase transition from amorphous to polycrystalline at 300 °C, and then to single crystalline at 500 °C, accompanied by an increase in the bandgap from 4.6 to 4.9 eV. We also fabricate metal-semiconductor–metal photodetectors based on the ZnGa2O4 thin films with Ti/Au electrodes, which exhibit excellent Ohmic contact and high light-to-dark current ratio. The photodetectors show remarkable and stable DUV response, with the highest performance achieved at a substrate temperature of 650 °C. Our results demonstrate the crucial role of substrate temperature in tailoring the crystal structure and DUV photodetection of ZnGa2O4 thin films, and provide a facile route for optimizing their performance.
Resolution Enhancement of SOHO/MDI Magnetograms
Authors: Qin Ying , Ji Kai-Fan , Liu Hui , Yu Xiao-Guang
Published: April 2024

Research on the solar magnetic field and its effects on solar dynamo mechanisms and space weather events has benefited from the continual improvements in instrument resolution and measurement frequency. The augmentation and assimilation of historical observational data timelines also play a significant role in understanding the patterns of solar magnetic field variation. Within the realm of astronomical data processing, super-resolution (SR) reconstruction refers to the process of using a substantial corpus of training data to learn the nonlinear mapping between low-resolution (LR) and high-resolution (HR) images, thereby achieving higher-resolution astronomical images. This paper is an application study in high-dimensional nonlinear regression. Deep learning models were employed to perform SR modeling on SOHO/MDI magnetograms and SDO/HMI magnetograms, thus reliably achieving resolution enhancement of full-disk SOHO/MDI magnetograms and enhancing the image resolution to obtain more detailed information. For this study, a data set comprising 9717 pairs of data from 2010 April to 2011 February was used as the training set, 1332 pairs from 2011 March were used as the validation set and 1034 pairs from 2011 April were used as the test set. After data preprocessing, we randomly cropped 128 × 128 sub-images as the LR cases from the full-disk MDI magnetograms, and the corresponding 512 × 512 sub-images as HR ones from the HMI full-disk magnetograms for model training. The tests conducted have shown that the study successfully produced reliable 4× SR reconstruction of full-disk MDI magnetograms. The MESR model’s results (0.911) were highly correlated with the target HMI magnetographs as indicated by the correlation coefficient values. Furthermore, the method achieved the best PSNR, SSIM, MAE and RMSE values, indicating that the MESR model can effectively reconstruct magnetograms.
Role of turbulent separatrix tangle in the improvement of the integrated pedestal and heat exhaust issue for stationary-operation tokamak fusion reactors
Authors: Chang C.S. , Ku S. , Hager R. , Choi J. , Pugmire D. , Klasky S. , Loarte A. , Pitts R.A
Published: April 2024

The magnetic separatrix surface is designed to provide the final and critical confinement to the hot stationary-operation core plasma in modern tokamak reactors in the absence of an external magnetic perturbation (MP) or transient magneto-hydrodynamic perturbation, while diverting the exhaust heat to divertor plates. All the stationary operational boundary plasma studies and reactor designs have been performed under this assumption. However, there has been a long-standing suspicion that a stationary-operation tokamak plasma even without external MPs or edge localized modes (ELMs) activities may not have a stable closed separatrix surface, especially near the magnetic X-point. Here, the first gyrokinetic numerical observation is reported that the divertor separatrix surface, due to homoclinic tangles caused by intrinsic electromagnetic turbulence, is not a stable closed surface in a stationary operation phase even without MPs or ELMs. Unlike the MP- or ELM-driven homoclinic tangles that could cause deleterious effects to core confinement or divertor plates, it is found that the micro-turbulence driven homoclinic tangles could connect the divertor plasma to the pedestal plasma in a constructive way by broadening the divertor heat-exhaust footprint and weakening the pedestal slope to the ELM-safe direction. Micro-turbulent homoclinic tangles can open a new research direction in understanding and controlling these two most troublesome and non-locally connected edge-plasma issues in a tokamak fusion reactor.
Optical modeling of atmospheric black carbon aerosol ensembles with complex particle morphology
Authors: Wu Yu , Zheng Lijuan , Wu Yuhan , Wang Zeyu , Guo Yanming
Published: April 2024

Black carbon (BC) aerosol is one of the most important factor in global warming. BC radiative forcing remains unconstrained, mainly because of the uncertain parameterizations of its absorption and scattering properties in the atmosphere. The single sphere model is widely used in current climate assessment of BC aerosols due to its computational convenience, however, their complex morphologies in particle level are excessively simplified which leads to computed inaccuracy. In this study, we present a dynamic model for optical calculations of BC aerosol ensembles considering their complex fractal aggregate morphologies with the constraint of max monomer numbers (N
s, max) and radius (a
max). We show that the simulation accuracy of the dynamic model with suitable values of N
s, max and a
max may achieve ∼95% while the computation time may reduce to ∼6%. We find that optical properties of BC aerosol ensembles can be simulated for higher accuracy or faster calculation by performing different selections of monomer numbers and radius in their size distributions. This method enables extensive and accurate optical calculations of BC particles with complex morphologies, which would be useful for the remote sensing inversion and the assessment of climate.
Uniform vs. uneven lighting: Accommodation of multiple users’ preferences in study rooms
Authors: Gkolompia Evdoxia Iro
Published: April 2024

Uniform lighting in public spaces like study rooms in libraries, is still a common practice. However, uniformly lit spaces are unable to simultaneously meet the needs of multiple users and can create dull environments. The objective of this research is to analyze users’ behavior under different lighting conditions in study rooms and investigate whether alternative lighting designs, which step away from uniformity, could be more beneficial than uniform lighting, from a human performance and well-being perspective. A uniformly lit study room in the library of KTH was chosen as the main case study of this investigation and was thoroughly analyzed and evaluated through qualitative and quantitative research. Under the initial hypothesis that the lighting in this study room does not meet its users’ needs and fails to create an inspiring and comfortable environment, three additional study rooms in different Swedish libraries were comparatively analyzed through observations, interviews, and questionnaires, so as to better understand individual users’ needs and lighting preferences in study rooms. The research revealed the existence of various types of users with different personal preferences regarding lighting in order to feel comfortable and alert. A new conceptual lighting proposal is presented for the study room in KTH library, following an uneven lighting approach that utilizes different lighting zones to accommodate individual needs and affect the sense of comfort, alertness, and ultimately, the well-being of multiple types of users.
The Use of Immersive Light-Based Art for Well-Being
Authors: Godley L , Frasso R , Igoe T , Erel Y , LeNoir J
Published: April 2024

This paper presents the findings of ‘Waiting Room - Immersive Art for Well-being,’ an exhibition of various dynamic light art installations that investigated the potential impact of this work on viewers’ sense of well-being in a mock healthcare setting. Research shows that exposure to art impacts human health, improving overall healthcare experiences, resulting in shortened hospital stays, improved recovery time, and reduced need for pain management. The purpose of this study was to determine if exposure to dynamic light art has an impact on overall well-being. Qualitative data were collected using electronic questionnaires associated with 11 different dynamic light art installations. Open-ended questions explored how participants perceived and valued the presence of and engagement with dynamic light art installations and captured their views on the potential benefit of exposure. Visitors took part in questionnaires to obtain feedback on user experience, the length of exposure/engagement, and the effect the experience had on them. Overwhelmingly, users reported a sense of “calm” and “peacefulness” after spending time with the dynamic light art. One hundred ninety-five responses were collected. This study allowed us to gain a better understanding of how dynamic light art may be used to ameliorate stress and anxiety in spaces where users are confined for periods, as well as identifying key areas for future research, such as particular aspects of the installations or sub-populations that may particularly benefit from this type of intervention. This investigation leads to further studies exploring how exposure to dynamic light art may impact patients, visitors, and family members in various healthcare settings to determine if the perceptions and experiences vary by type of installation. Additionally, this work will inform future explorations of adaptations to dynamic light art, i.e., dynamic and interactive technologies on viewer experience.
Indirect lighting in Contemplative Spaces – an Endless Depth
Authors: Mirson Juan Carlos
Published: April 2024

This paper explores the relationship between indirect lighting and contemplative spaces. Through an examination of notable architectural works, the study identifies a consistent preference for hidden light sources in contemplative spaces across various religions and eras. The research begins by defining the fundamental aspects of contemplation and its correlation with architecture. This is followed by a bibliographic survey of indirectly illuminated contemplative spaces. Within this investigation, three approaches to understanding these spaces are considered. Firstly, the conceptual ideas that architects sought to infuse into their creations; secondly, sensory descriptions provided by experts aimed at elucidating the luminous atmospheres of these locations. Lastly, the study delves into these diverse themes through the lens of phenomenology, highlighting perceptual peculiarities such as the predominance of sight, the significance of peripheral stimuli, and hapticity. This offers insights into the relationship between specific attributes of indirect lighting and transcendental architectural experiences. The consistent suggestion of perceiving endless depth in contemplative spaces prompts a brief discussion on the essence of our perception of depth. This study underscores light’s significance as a tool to connect with architectural spaces, transforming them into realms of imagination and awe.
Embedding sustainability into the design of street lighting
Authors: Wåseth H I , Safi J , Nielsen T K , Bayr U , Johansen N , Fjeldaas E , Christensen T
Published: April 2024

Light pollution is an increasing problem and Artificial Light at Night (ALAN) affects nature in many ways. The Norwegian Road Authorities (SVV) initiated a collaboration with the Norwegian Institute for Bioeconomy (NIBIO) and the University of South-Eastern Norway (USN) to find measures that can help reduce the negative impacts of road lighting on the environment and nature. While USN has looked more generally at sustainable lighting design and ways to reduce the negative effects of road lighting, NIBIO has focused on how road lighting affects insects. We study how the light from roads contributes to light pollution, with the final aim to know more about what measures most effectively reduce the negative effects of road lighting. In this pilot study of light levels in two transects beside a road, the results show that the light levels decreased relatively fast as the distance to the light source increased. Thus, the direct light from the road lighting might not be the most prominent addition to the light pollution in the open landscape. On the other hand, the measurements showed some light influence from the road up to around 160 meters from the road, although the levels were low. While the light was below the detection limit, the light source was visible as a point source at a very large distance. This observation addresses the question of whether organisms are influenced by the average light energy per area, or the intensity of a source as observed from a distance (irradiance vs. radiance). Additional sources of light pollution may affect the result, such as unshielded private light sources and sky glow. This project aims to find measures that can help reduce the negative impacts of road lighting on the environment and nature. We study how the light from roads contributes to different components of light pollution, like skyglow, light trespass and luminance from the light source.
A Framework for Optimizing Lighting in Animal Shelters for Domestic Cats
Authors: Baertlein Kendall , Scheib Jennifer , Baker Kyri
Published: April 2024

In this project, we aim to enable designers to optimize lighting conditions for domestic cats in animal shelters. Specifically, we developed an optimization framework that controls the spectral power distribution (SPD) of light sources and returns the effect on feline visual perception. In our model, we used standard light source SPDs and predicted light reflected from different surfaces within an animal shelter. The reflected SPDs were combined with the known brightness sensitivity of domestic cats across the visible light spectrum to develop an understanding of cats’ visual experience in the shelter under different lighting conditions. The optimization framework then minimizes the difference between a desired lighting effect (here, daylight) and a modeled effect using a set of light source SPDs. Initial results demonstrate that by using slightly more advanced lighting design and control, shelters can potentially improve the visual experience for cats.
Skynative – brings daylight into the depths of buildings
Authors: Hauer Martin , Knoflach Christian , Kissling Elise , Mehlhorn Lutz , Gross Judith
Published: April 2024

There are various ways of directing daylight into the interior of a building or a room. In cooperation with BASF, Bartenbach has developed a prototype of a horizontal daylight duct integrated into the suspended ceiling that efficiently transports daylight from the outside into the underexposed “core” of a building. “Skynative” is the name of the system, named after BASF spin-off Skynative® UG, which is working on market integration as well as continuous improvement of the system in an open research collaboration with Bartenbach. In this paper, the system concept development, simulation-based application studies as well as the setup of a real-scale mock-up, including results from a long-term performance monitoring at the premises at Bartenbach, are presented. First potential application projects are shown, and the system efficiency is discussed.