bluuebunny/crossref_metadata_2025 huggingface dataset:
Correction: Recent progress in eutectic gallium indium (EGaIn): surface modification and applications
Authors: Ge Wensong , Wang Rui , Zhu Xiaoyang , Zhang Houchao , Sun Luanfa , Wang Fei , Li Hongke , Li Zhenghao , Du Xinyi , Chen Huangyu , Zhang Fan , Shi Huifa , Hu Huiqiang , Xi Yongming , He Jiankang , Hu Liang , Lan Hongbo
Published: January 2024

Correction for ‘Recent progress in eutectic gallium indium (EGaIn): surface modification and applications’ by Wensong Ge et al., J. Mater. Chem. A, 2024, 12, 657–689, https://doi.org/10.1039/D3TA04798A.
The Consumer Acceptance of Novel Foods on Potential Markets using An Extended Behavior Model
Authors: Satria Awang Tri , Aghniarahim Putritamara Jaisy
Published: January 2024

This research aims to determine the purchase intention of cultured meat using an expanded planned behavior theory approach. The development of science has encouraged scientists to look for the latest innovations known as novel foods with the aim of alternative food in the future. Research on consumer acceptance of cultured meat has been carried out in many developed countries by looking at the potential for various consumer acceptance of cultured meat. Indonesia, as one of the potential markets for novel foods, is necessary to also look at the potential for consumer acceptance of novel foods, especially on cultured meat. This research used an online survey method on 231 young respondents in Indonesia. The results show that constructive attitudes and subjective norms significantly affect the purchase intention of cultured meat. Environmental beliefs also significantly affect the purchase intention of cultured meat. The results of this research can be used as a reference for marketing strategies for cultured meat in the future, especially in the young age segment in potential markets in developing countries.
Can digital economy truly improve agricultural ecological transformation? New insights from China
Authors: Hou Jian , Zhang Mengyao , Li Ye
Published: January 2024

As the world’s biggest emitter of carbon, China’s agricultural carbon emissions account for 16 to 17%, with agriculture being the second largest contributor to carbon emissions. The development of the digital economy has brought profound changes to agricultural ecology. Therefore, we utilize China’s data experience to construct an agricultural ecological transformation system by setting up a Super-SBM model. Then, based on a dynamic panel threshold model, we explore the nonlinear impact mechanism of the digital economy on agricultural ecological transformation from a low-carbon innovation perspective. Our results reveal that the overall level of China’s agricultural ecological transformation is not high, but in the long-term posture, it represents a relatively steady upward trend, with a significant “wealth gap” between different regions. It is worth noting that there is a significant threshold effect of low-carbon innovation heterogeneity in the impact mechanism of digital economy on agricultural ecological transformation: under lower low-carbon innovation levels, the development of digital economy is unable to effectively promote agricultural ecological transformation. However, as the level of low-carbon technological innovation increases and exceeds the critical value, it stimulates the driving effect of digital economy to some extent, thereby promoting the improvement of agricultural ecological transformation, presenting a “U” shaped relationship. The paper has clarified the differential “new phenomena” in the process of promoting agricultural ecological transformation, providing new insights for achieving “carbon reduction and economic promotion” in developing countries.
Dynamic mode decomposition for Koopman spectral analysis of elementary cellular automata
Authors: Taga Keisuke , Kato Yuzuru , Yamazaki Yoshihiro , Kawahara Yoshinobu , Nakao Hiroya
Published: January 2024

We apply dynamic mode decomposition (DMD) to elementary cellular automata (ECA). Three types of DMD methods are considered, and the reproducibility of the system dynamics and Koopman eigenvalues from observed time series is investigated. While standard DMD fails to reproduce the system dynamics and Koopman eigenvalues associated with a given periodic orbit in some cases, Hankel DMD with delay-embedded time series improves reproducibility. However, Hankel DMD can still fail to reproduce all the Koopman eigenvalues in specific cases. We propose an extended DMD method for ECA that uses nonlinearly transformed time series with discretized Walsh functions and show that it can completely reproduce the dynamics and Koopman eigenvalues. Linear-algebraic backgrounds for the reproducibility of the system dynamics and Koopman eigenvalues are also discussed.
Lag and duration of leader–follower relationships in mixed traffic using causal inference
Authors: Africa David Demitri , Dy Quiangco Ronald Benjamin , Go Clark Kendrick
Published: January 2024

This study presents comprehensive analysis of car-following behavior on roads, utilizing Granger causality and transfer entropy techniques to enhance the validity of existing car-following models. It was found that most leader–follower relationships exhibit a delay in lateral movement by 4–5 s and last for short periods of around 3–5 s. These patterns are exhibited for all types of relationship found in the dataset, as well as for followers of all types. These findings imply that lateral movement reactions are governed by a different set of rules from braking and acceleration reactions, and the advantage in following lateral changes is short-lived. This also suggests that mixed traffic conditions may force drivers to slow down and calibrate reactions, as well as limiting the speed advantage gained by following a leader. Our methods were verified against random sampling as a method of selecting leader–follower pairs, decreasing the percent error in predicted speeds by 9.5% using the optimal velocity car-following model. The study concludes with a set of recommendations for future work, including the use of a diversity of car-following models for simulation and the use of causation entropy to distinguish between direct and indirect influences.
Broadband enhancement and high extraction efficiency from single quantum dots embedded in microlenses coupled with a gold mirror
Authors: Liu Hanqing , Li Shulun , Shang Xiangjun , Huang Junhui , Liu Shunfa , Su Xiangbin , Sun Baoquan , Dai Deyan , Zhang Yu , Liu Bing , Liu Jin , Ni Haiqiao , Niu Zhichuan
Published: January 2024

We present a broadband enhanced single photon source device of Gaussian-shaped GaAs microlens (ML) arrays coupled with a gold bottom mirror hybrid structure. The extrapolated light extraction efficiency of (60.6 ± 1.5)% at maximum (for collection numerical aperture = 0.45 and based on the an actually measured raw detection efficiency of ∼0.775%) and a broad spectral band of 890–960 nm were obtained. The ML-Au structure with embedded epitaxial quantum dots exhibits a high single-photon purity of (96.6 ± 0.7)% [g(2)(0) = 0.034 ± 0.003] under pulsed excitation with 20% saturation. Wet-etched microlenses with smooth surfaces achieve simultaneous enhancement of both XX and X exciton emissions, which is prerequisite for promising entangled photon pair generation. This work proposes the bright potential of integrated hybrid structures to enable further photon pair entanglement applications.
Complex localization mechanisms in networks of coupled oscillators: Two case studies
Authors: Nicolaou Zachary G. , Bramburger Jason J.
Published: January 2024

Localized phenomena abound in nature and throughout the physical sciences. Some universal mechanisms for localization have been characterized, such as in the snaking bifurcations of localized steady states in pattern-forming partial differential equations. While much of this understanding has been targeted at steady states, recent studies have noted complex dynamical localization phenomena in systems of coupled oscillators. These localized states can come in the form of symmetry-breaking chimera patterns that exhibit coexistence of coherence and incoherence in symmetric networks of coupled oscillators and gap solitons emerging in the bandgap of parametrically driven networks of oscillators. Here, we report detailed numerical continuations of localized time-periodic states in systems of coupled oscillators, while also documenting the numerous bifurcations they give way to. We find novel routes to localization involving bifurcations of heteroclinic cycles in networks of Janus oscillators and strange bifurcation diagrams resembling chaotic tangles in a parametrically driven array of coupled pendula. We highlight the important role of discrete symmetries and the symmetric branch points that emerge in symmetric models.
Solitons and lumps in the cylindrical Kadomtsev–Petviashvili equation. II. Lumps and their interactions
Authors: Zhang Zhao , Hu Wencheng , Guo Qi , Stepanyants Yury
Published: January 2024

We study solitary waves in the cylindrical Kadomtsev–Petviashvili equation designated to media with positive dispersion (the cKP1 equation). By means of the Darboux–Matveev transform, we derive exact solutions that describe two-dimensional solitary waves (lumps), lump chains, and their interactions. One of the obtained solutions describes the modulation instability of outgoing ring solitons and their disintegration onto a number of lumps. We also derive solutions describing decaying lumps and lump chains of a complex spatial structure—ripplons. Then, we study normal and anomalous (resonant) interactions of lump chains with each other and with ring solitons. Results obtained agree with the numerical data presented in Part I of this study [Hu et al., Chaos (2024)].
Design optimization of anti-splashing targets and simulation of droplet impact on it
Authors: Chy Md. Hedayetul Islam , Biswas Riya , Kader Md. Fazlul , Wan Yuan , Mahmood Mohammed Arif Iftakher
Published: January 2024

Natural surfaces have micro and nanostructures that affect the splashing behavior of water droplets falling on them. Synthetic surfaces mimicking this natural phenomenon have been previously reported. The objective of our current work is to design such surfaces and fine-tune the fluid splashing behavior using three-dimensional simulation tools. We have designed and simulated splashing behavior on geometrically patterned micro scale surfaces using the volume of fluid method within the commercial software Ansys Fluent. Surfaces with microscale pillars of different heights, geometrical shapes, layouts as well as tip designs were simulated with the goal of minimizing fluid splash. We found that certain pillar models produce less splashes than others. We have further optimized array structures for fluid splashing diameter and velocity. Behavior at different falling angles and fluid types are also investigated in multi-pillar models. The results indicate that a non-uniform structured surface decreases the speed and energy of the falling droplet. We have reported here three finalized designed models that are 35%, 63.5%, and 69% effective in reducing velocity compared to a flat surface model.
Electrical and thermal characteristics of LaB6 thermionic hollow cathodes operating in He, D2, Ar, and Xe at 4–200 Pa and 0.25–5 A cm−2
Authors: Meshkov Andrey I. , Trotter Camellia A. , Sommerer Timothy J. , Smith David J.
Published: January 2024

We report characteristics of lanthanum hexaboride (LaB6) cathodes for conditions relevant to a high-voltage, high-current switching device. LaB6 is selected because of its relatively low work function, stability in the presence of many common gas impurities, and a low evaporation rate (long life) at operating temperatures. We have investigated the effect of cathode geometry, gas type, pressure, and current on a LaB6 hollow cathode in a diode configuration with an opposing planar anode. The gas is stagnant at a relatively low pressure of 4–200 Pa (0.03–1.5 Torr) because of device high-voltage standoff requirements. In all cases, the plasma voltage decreases to a plateau value with increasing current where a practical device would operate. The plateau voltage aligns with the fill gas excitation or ionization voltage, depending on conditions. At high current, the cathode temperature exceeds that required for thermionic emission to supply the total current, a behavior that is understood by accounting for back-diffusing bulk electrons.
Lattice Boltzmann method for warm fluid simulations of plasma wakefield acceleration
Authors: Simeoni Daniele , Parise Gianmarco , Guglietta Fabio , Rossi Andrea Renato , Rosenzweig James , Cianchi Alessandro , Sbragaglia Mauro
Published: January 2024

A comprehensive characterization of lattice Boltzmann (LB) schemes to perform warm fluid numerical simulations of particle wakefield acceleration (PWFA) processes is discussed in this paper. The LB schemes we develop hinge on the moment matching procedure, allowing the fluid description of a warm relativistic plasma wake generated by a driver pulse propagating in a neutral plasma. We focus on fluid models equations resulting from two popular closure assumptions of the relativistic kinetic equations, i.e., the local equilibrium and the warm plasma closure assumptions. The developed LB schemes can, thus, be used to disclose insights on the quantitative differences between the two closure approaches in the dynamics of PWFA processes. Comparisons between the proposed schemes and available analytical results are extensively addressed.
Effects of electrolyte/cathode ratio on investigation of their thermal behaviors using differential scanning calorimetry
Authors: Xu Xilin , Gan Luyu , Chen Rusong , Wang Junyang , Cai Zhuoyuan , Yu Xiqian , Li Hong , Huang Xuejie
Published: January 2024

Battery materials with high-energy density and good safety performance have been regarded as the ultimate target for larger-scale applications of lithium-ion batteries in electric transportation and grid energy storage. Thermal safety of high energy density cathode materials has been a hot topic for battery safety research in recent years. Differential scanning calorimetry (DSC) is widely used to investigate thermal reaction characteristics of battery materials, but the results are always affected by multiple variables, e.g., sample pre-processing and testing conditions. The variety of DSC results reported in literature have been perplexing the research community. Herein, the cathode-electrolyte system is chosen to reveal the changes of reaction mechanisms with different electrolyte/cathode ratios, since this system has been widely adopted to characterize thermal stability of cathodes and electrolytes in previous studies. Lithium-rich manganese-based layered oxide cathode and ester-based electrolyte are selected as representative samples. Our results reveal that flooded, sufficient, insufficient, and lean electrolyte conditions may lead to distinct thermal behaviors from probably different reaction routines, which may hold different reference values for battery-level safety analysis. This study also suggests the importance of systematic investigations on test conditions in battery material thermal safety research.
First-order crosstalk mitigation in parallel quantum gates driven with multi-photon transitions
Authors: Chow Matthew N. H. , Yale Christopher G. , Burch Ashlyn D. , Ivory Megan , Lobser Daniel S. , Revelle Melissa C. , Clark Susan M.
Published: January 2024

We demonstrate an order of magnitude reduction in the sensitivity to optical crosstalk for neighboring trapped-ion qubits during simultaneous single-qubit gates driven with individual addressing beams. Gates are implemented via two-photon Raman transitions, where crosstalk is mitigated by offsetting the drive frequencies for each qubit to avoid first-order crosstalk effects from inter-beam two-photon resonance. The technique is simple to implement, and we find that phase-dependent crosstalk due to optical interference is reduced on the most impacted neighbor from a maximal fractional rotation error of 0.185(4) without crosstalk mitigation to ≤0.006 with the mitigation strategy. Furthermore, we characterize first-order crosstalk in the two-qubit gate and avoid the resulting rotation errors for the arbitrary-axis Mølmer–Sørensen gate via a phase-agnostic composite gate. Finally, we demonstrate holistic system performance by constructing a composite CNOT gate using the improved single-qubit gates and phase-agnostic two-qubit gate. This work is done on the Quantum Scientific Computing Open User Testbed; however, our methods are widely applicable for individual addressing Raman gates and impose no significant overhead, enabling immediate improvement for quantum processors that incorporate this technique.
Fast-charging graphite anode for lithium-ion batteries: Fundamentals, strategies, and outlooks
Authors: Yan Xin , Jiao Jinying , Ren Jingke , Luo Wen , Mai Liqiang
Published: January 2024

The basic requirements for lithium-ion batteries in the field of electric vehicles are fast charging and high energy density. This will enhance the competitiveness of electric vehicles in the market while reducing greenhouse gas emissions and effectively preventing environmental pollution. However, the current lithium-ion batteries using graphite anodes cannot achieve the goal of fast charging without compromising electrochemical performance and safety issue. This article analyzes the mechanism of graphite materials for fast-charging lithium-ion batteries from the aspects of battery structure, charge transfer, and mass transport, aiming to fundamentally understand the failure mechanisms of batteries during fast charging. In addition, we review and discuss recent advances in strategies for optimizing fast-charging performance and summarize current improvement methods in graphite electrodes, electrolytes, battery structures, and charging algorithms. Moreover, the challenges and promising concepts for developing future fast-charging graphite anode are emphasized. This review is of great significance for better designing and optimizing graphite materials for high-safety and fast-charging lithium-ion batteries.
Investigations of the exchange energy of neutral atoms in the large-Z limit
Authors: Redd Jeremy J. , Cancio Antonio C. , Argaman Nathan , Burke Kieron
Published: January 2024

The non-relativistic large-Z expansion of the exchange energy of neutral atoms provides an important input to modern non-empirical density functional approximations. Recent works report results of fitting the terms beyond the dominant term, given by the local density approximation (LDA), leading to an anomalous Z ln Z term that cannot be predicted from naïve scaling arguments. Here, we provide much more detailed data analysis of the mostly smooth asymptotic trend describing the difference between exact and LDA exchange energy, the nature of oscillations across rows of the Periodic Table, and the behavior of the LDA contribution itself. Special emphasis is given to the successes and difficulties in reproducing the exchange energy and its asymptotics with existing density functional approximations.
Exploring Hopf-bifurcations and endemic bubbles in a tuberculosis model with behavioral changes and treatment saturation
Authors: Das Saduri , Srivastava Prashant K. , Biswas Pankaj
Published: January 2024

To manage risks and minimize the transmission of contagious diseases, individuals may reduce their contact with each other and take other precautions as much as possible in their daily lives and workplaces. As a result, the transmission of the infection reduces due to the behavioral changes. These behavioral changes are incorporated into models by introducing saturation in disease incidence. In this article, we propose and analyze a tuberculosis model that incorporates saturated exogenous reinfection and treatment. The stability analysis of the model’s steady states is rigorously examined. We observe that the disease-free equilibrium point and the endemic equilibrium point (EEP) are globally asymptotically stable if the basic reproduction number (R0) is less than 1 and greater than 1, respectively, only when exogenous reinfection is not present (p=0) and when treatment is available for all (ω=0). However, even when R0 is less than 1, tuberculosis may persist at a specific level in the presence of exogenous reinfection and treatment saturation, leading to a backward bifurcation in the system. The existence and direction of Hopf-bifurcations are also discussed. Furthermore, we numerically validate our analytical results using different parameter sets. In the numerical examples, we study Hopf-bifurcations for parameters such as β, p, α, and ω. In one example, we observe that increasing β leads to the loss of stability of the unique EEP through a forward Hopf-bifurcation. If β is further increased, the unique EEP restores its stability, and the bifurcation diagram exhibits an interesting structure known as an endemic bubble. The existence of an endemic bubble for the saturation constant ω is also observed.
Enhancing indium bilayer nitridation through novel hydrogen insertion process in InN epitaxy: A kinetic mechanism
Authors: Zhou Jin , Liu Yansheng , Dong Xinwei , Guo Fei , Fu Jianbo
Published: January 2024

InN holds great promise for a wide range of applications, including broadband optical devices, high-frequency electronic devices, and serving as a substrate for highly sensitive gas detectors and efficient catalysts. Nevertheless, production of high-quality InN thin films through epitaxy has remained a significant challenge. This is primarily due to complexities arising from the low dissociation temperature and the high N2 equilibrium pressure of InN, which lead to formation of numerous nitrogen vacancies and a propensity to generate indium metal nanoparticles. Efficacy of the indium bilayer pre-deposition method for InN film growth has been established in prior studies. In this work, we introduce a specialized hydrogen insertion method to further enhance nitridation of the indium bilayer. The corresponding kinetic mechanism has been demonstrated through theoretical simulations and practical epitaxy experiments, leading to the development of an optimized hydrogen insertion process. This research represents a substantial improvement over existing InN epitaxial methods that involve control of the indium bilayer and introduces a novel mechanism for enhancing InN heteroepitaxy.
β
-rays induced displacement damage on epitaxial 4H-SiC revealed by exciton recombination
Authors: Migliore F. , Alessi A. , Principato F. , Girard S. , Cannas M. , Gelardi F. M. , Lombardo A. , Vecchio D. , Brischetto A. , Agnello S.
Published: January 2024

One of the most interesting wide-bandgap semiconductor is 4H-SiC that has an indirect wide-bandgap of 3.3 eV. This material holds great potential to develop power devices that find applications in the field of high-voltage and high-temperature electronics and harsh environments. In this study, we employed complementary noninvasive characterization techniques, including micro-Raman, optical absorption, steady-state, and time-resolved photoluminescence spectroscopy, to investigate the characteristics of a 12 μm thick epitaxial layer of 4H-SiC grown on 4H-SiC. Furthermore, we explored the impact of ionizing radiation on this material, utilizing β-rays and two x-ray sources. The doses are in the range of 1–100 kGy for electrons with energy of 2.5 MeV, 16 kGy for the first x-ray source (an x-ray tube with a W target operating at an anode bias voltage of 28 kV), and 100 kGy for the second x-ray source (an x-ray tube with a W target operating at an anode bias voltage of 100 kV). When exposed to the electron beam, the excitonic band at 3.2 eV exhibits a reduction in its lifetime as the deposited dose increases. In particular, in samples characterized by a greater amount of native defects, both extended and point defects, this effect becomes evident at lower deposited doses. Conversely, in the samples subjected to x-ray irradiation, these effects are not observed. These findings indicate that electron beam irradiation triggers the formation of defects associated with atomic displacement. Ultimately, we have examined the impact of thermal treatments in air, ranging from 100 to 900 °C, to investigate the recovery characteristics of 4H-SiC.
Nanoscopic spin-wave channeling along programmable magnetic domain walls in a CoFeB/BaTiO3 multiferroic heterostructure
Authors: Zhu Weijia , Qin Huajun , van Dijken Sebastiaan
Published: January 2024

We report a micromagnetic study on spin-wave propagation along magnetic domain walls in a ferromagnetic/ferroelectric bilayer. In our system, strain coupling between the two ferroic materials and inverse magnetostriction produce a fully correlated domain pattern wherein straight and narrow ferroelectric domain walls pin the magnetic domain walls. Consequently, an external magnetic field does tailor the spin structure of the magnetic domain walls instead of moving them. We use experimental parameters from a previously studied CoFeB/BaTiO3 material system to investigate the potential of artificial multiferroics for programmable nanoscopic spin-wave channeling. We show that spin waves are transported along the pinned magnetic domain walls at zero magnetic field and low frequency due to a local demagnetizing field. Further, switching of the domain wall spin structure from a head-to-tail to a head-to-head configuration abruptly changes the propagating spin-wave mode. We study the effect of magnetic field strength on the localized modes and discuss reversible control of spin-wave channeling via electric-field-driven magnetic domain wall motion. Nanoscopic guiding of propagating spin waves by an electric field, in combination with positional robustness to and mode programming by an external magnetic field, offers prospects for low-power and reconfigurable domain-wall-based magnonic devices.
Evaporative cooling and reaction of carbon dioxide clusters by low-energy electron attachment
Authors: Fan Mengyuan , Xie Jingchen , Wang Enliang , Tian Shan Xi
Published: January 2024

Anionic carbonate CO3− has been found in interstellar space and the Martian atmosphere, but its production mechanism is in debate so far. To mimic the irradiation-induced reactions on icy micrograins in the Martian atmosphere and the icy shell of interstellar dust, here we report a laboratory investigation on the dissociative electron attachments to the molecular clusters of CO2. We find that anionic species (CO2)n−1O− and (CO2)n− (n = 2, 3, 4) are produced in the concerted reaction and further stabilized by the evaporative cooling after the electron attachment. We further propose a dynamics model to elucidate their competitive productions: the (CO2)n− yields survive substantially in the molecular evaporative cooling at the lower electron attachment energy, while the reactions leading to (CO2)n−1O− are favored at the higher attachment energy. This work provides new insights into physicochemical processes in CO2-rich atmospheres and interstellar space.
Size characterization of x-ray tube source with sphere encoded imaging method
Authors: Yu Jian , Li Dikai , Dai Yanmeng , Zhang Chunhui , Chen Wei , Zhong Jian , Wang Xue , Xia Runxiang , Cao Leifeng , Zhou Cangtao , Ruan Shuangchen
Published: January 2024

In x-ray imaging, the size of the x-ray tube light source significantly impacts image quality. However, existing methods for characterizing the size of the x-ray tube light source do not meet measurement requirements due to limitations in processing accuracy and mechanical precision. In this study, we introduce a novel method for accurately characterizing the size of the x-ray tube light source using spherical encoded imaging technology. This method effectively mitigates blurring caused by system tilting, making system alignment and assembly more manageable. We employ the Richardson–Lucy algorithm to iteratively deconvolve the image and recover spatial information about the x-ray tube source. Unlike traditional coded imaging methods, spherical coded imaging employs high-Z material spheres as coding elements, replacing the coded holes used in traditional approaches. This innovation effectively mitigates blurring caused by system tilting, making system alignment and assembly more manageable. In addition, the mean square error is reduced to 0.008. Our results demonstrate that spherical encoded imaging technology accurately characterizes the size of the x-ray tube light source. This method holds significant promise for enhancing image quality in x-ray imaging.
A numerical study of the effects of jet-aft wall temperatures on the dynamics of jets in hypersonic crossflows
Authors: Rowton Harry C. , Medwell Paul R. , Chin Rey
Published: January 2024

For high-speed vehicles such as scramjets, internal combustion chamber temperatures play an important role in the engine performance, with the influence of the temperature on the fuel injection dynamics being of key interest. In this study, large eddy simulations are employed to investigate a sonic jet in a Mach 5 crossflow with a momentum flux ratio of 5.8 and the parametrization of the temperature of the wall aft of the jet. Both uniform and non-uniform wall temperatures are analyzed, with two jet-to-crossflow temperature ratios of 8.06 and 3.23 investigated. It is found that the wall temperature primarily influences the near wall flow, with a small amount of entrainment into the jet plume via the counter-rotating vortex pair as the low velocity flow is limited by the near-wall shear layer. It is found that the aft-recirculation zone is expanded with the increasing wall temperature, which has the effect of increasing the penetration of the jet plume into the far field. Five recirculation regions are observed ahead of the jet, which are noted to result from the interaction between the crossflow and jet flow for both the adiabatic and temperature-controlled cases, with jet fluid flowing into the forward boundary layer, and thus near-wall mixing is observed. Horseshoe vortex strength is seen to dissipate when passing over the cooled walls, thus reducing the mixing potential near the wall, where the opposite is true for heated walls. Lateral spread of the horseshoe vortices is seen to increase with cooled walls, increasing the near-wall mixing potential.
Predicting Braess's paradox of power grids using graph neural networks
Authors: Zou Yanli , Zhang Hai , Wang Hongjun , Hu Jinmei
Published: January 2024

As an increasing number of renewable energy generators are integrated into the electrical grid, the necessity to add new transmission lines to facilitate power transfer and ensure grid stability becomes paramount. However, the addition of new transmission lines to the existing grid topology can lead to the emergence of Braess's paradox or even trigger grid failures. Hence, predicting where to add transmission lines to guarantee stable grid operation is of utmost importance. In this context, we employ deep learning to address this challenge and propose a graph neural network-based method for predicting Braess's paradox in electrical grids, framing the problem of adding new transmission lines causing Braess's paradox as a graph classification task. Taking into consideration the topological and electrical attributes of the grid, we select node features such as degree, closeness centrality, and power values. This approach assists the model in better understanding the relationships between nodes, enhancing the model's representational capabilities. Furthermore, we apply layered adaptive weighting to the output of the graph isomorphism network to emphasize the significance of hierarchical information that has a greater impact on the output, thus improving the model’s generalization across electrical grids of varying scales. Experimental results on the IEEE 39, IEEE 57, and IEEE 118 standard test systems demonstrate the efficiency of the proposed method, achieving prediction accuracies of 93.8%, 88.8%, and 88.1%, respectively. Model visualization and ablation studies further validate the effectiveness of this approach.
Study of pristine and degraded blue quantum dot light-emitting diodes by transient electroluminescence measurements
Authors: Lin Wenxin , Huang Jiangxia , Li Shuxin , Blom Paul W. M. , Feng Haonan , Li Jiahao , Lin Xiongfeng , Guo Yulin , Liang Wenlin , Wu Longjia , Niu Quan , Ma Yuguang
Published: January 2024

Limited stability of blue quantum dot light-emitting diodes (QLEDs) under current stress impedes commercialization. Multi-layer structures of the state-of-the-art blue QLEDs pose significant difficulty in the fundamental understanding of degradation mechanisms. Here, by applying transient electroluminescence measurements, we disentangle charge transport in both pristine and degraded blue QLEDs. By varying thicknesses of the charge transport layers and the emissive layer, respectively, we show that the charge transport in pristine QLEDs is primarily dominated by holes. Furthermore, the degradation of QLEDs under electrical stress is governed by the decrease of hole transport in the emissive quantum dot layer due to the formation of hole traps.
Natural determinant reference functional theory
Authors: Yu Jason M. , Tsai Jeffrey , Rajabi Ahmadreza , Rappoport Dmitrij , Furche Filipp
Published: January 2024

The natural determinant reference (NDR) or principal natural determinant is the Slater determinant comprised of the N most strongly occupied natural orbitals of an N-electron state of interest. Unlike the Kohn–Sham (KS) determinant, which yields the exact ground-state density, the NDR only yields the best idempotent approximation to the interacting one-particle reduced density matrix, but it is well-defined in common atom-centered basis sets and is representation-invariant. We show that the under-determination problem of prior attempts to define a ground-state energy functional of the NDR is overcome in a grand-canonical ensemble framework at the zero-temperature limit. The resulting grand potential functional of the NDR ensemble affords the variational determination of the ground state energy, its NDR (ensemble), and select ionization potentials and electron affinities. The NDR functional theory can be viewed as an “exactification” of orbital optimization and empirical generalized KS methods. NDR functionals depending on the noninteracting Hamiltonian do not require troublesome KS-inversion or optimized effective potentials.
Effect of Archimedes number on the dynamics of free-falling perforated disks
Authors: Zhang Wenhui , Bi Dianfang , Wei Yingjie
Published: January 2024

The dynamics of perforated disks falling freely in a large expanse of viscous fluid at rest is investigated numerically. This complex fluid–structure interaction is solved via large eddy simulation. This numerical algorithm is verified and validated with available experimental results. The influence of Archimedes number expressing the ratio between the gravity-buoyancy and viscosity effects is discussed thoroughly, including kinematics and dynamics. Two critical Archimedes numbers are identified, Arcr1≈450 and Arcr2≈950, respectively. At these two critical Archimedes numbers, both kinematic and dynamic variables change trends. In this paper, we focus on the statistics of free-falling perforated disks. With the Archimedes number Ar increasing, the average angle of attack ⟨AoA⟩ and descent velocity ⟨Uz⟩ decrease gradually, and they arrive at a fixed value finally (here, ⟨·⟩ represents a time-average result); On the contrary, the other kinetic variables change violently when Ar is around 900, for example, terminal velocity ⟨Ut⟩. Additionally, phase differences of kinematic and dynamic variables are analyzed. A constant phase difference between the nutation angle θ and normal force FN is identified, about 66°, which is independent of Ar. Vortex structures are visualized using Q-criterion, and triangular vortex is omnipresent around holes. During the descent, a helical vortex always attaches to the perforated disk outer edge. With Ar increasing, complex vortex interaction appears, for example, merging and stretching. Some unusual behaviors in the numerical results are analyzed from the perspective of wake dynamics.
A critical review and meta-analysis of xenon-on-carbon sputter yield data
Authors: Polk James E.
Published: January 2024

A systematic review and meta-analysis of sputter yield data for xenon ions normally incident on graphite at energies below 2000 eV was undertaken to identify systematic errors, determine the best model parameter values to represent yield as a function of energy, quantify uncertainty, and determine if the data support differences in yields for different types of graphite. A critical examination of the 11 published data sets for high density graphite, pyrolytic graphite, and amorphous carbon showed that, in general, they were carefully controlled to minimize errors. The most significant quantifiable systematic errors were those caused by the neglect of doubly charged ions, chemical erosion, and the impact of secondary electron emission on ion flux measurements. The effects of gas uptake and outgassing on mass loss measurements and unrepresentative surface textures may have biased other experiments, but these effects could not be quantified. The semi-empirical Eckstein model for yield as a function of energy was fit to data for the three graphite types using a hierarchical Bayesian statistical model, producing recommended fit parameters and probability distributions representing uncertainty in yields. The results showed that differences in yield for high density graphite and pyrolytic graphite were not statistically significant. Apparent differences in yield for amorphous carbon disappeared when the single data set available for energies below 150 eV was corrected for reasonable values of double ion content. Recommended procedures to avoid systematic errors and additional experiments and modeling to fill in gaps in our understanding are included.
On the effectiveness of Reynolds-averaged and subgrid scale models in predicting flows inside car cabins
Authors: Grossi Giorgio , Arpino Fausto , Bertone Michele , Cortellessa Gino , Sciacchitano Andrea
Published: January 2024

The aim of the present study is to analyze the performances of unsteady Reynolds-averaged Navier–Stokes (URANS) and large eddy simulation (LES) approaches in predicting the airflow patterns inside car cabins and to give insight in the design of computational fluid dynamics simulations of a real car cabin. For this purpose, one eddy viscosity-based turbulence model (shear stress transport k–ω) and two subgrid scale models (wall-adapting local eddy-viscosity and dynamic kinetic energy) were tested, and numerical results were compared with particle image velocimetry measurements carried out on a commercial car. The URANS model exhibited great accuracy in predicting the mean flow behavior and was appreciably outperformed by the LES models only far from the inlet sections. For this reason, it was deemed suitable for conducting further analyses, aimed at characterizing the airflow patterns in winter and summer conditions and performing a thermal comfort analysis. The thermal regime was found to have a very little effect on the air flow patterns, once the quasi-steady state regime is achieved; in fact, both in winter and in summer, the temperature field is fairly uniform within the car cabin, making the contribution of buoyancy negligible and velocity fields to be very similar in the two seasons. Findings also reveal that thermal comfort sensation can be different for passengers sharing the same car but sitting on different seats; this aspect should be considered when designing and operating the ventilation system, since the minimum comfort requirements should be met for all the occupants.
Fractional averaging theory for discrete fractional-order system with impulses
Authors: Wang Peiguang , Liu Xiang , Anderson Douglas R.
Published: January 2024

In this paper, we improve the averaging theory on both finite and infinite time intervals for discrete fractional-order systems with impulses. By employing new techniques, generalized impulsive discrete fractional-order Gronwall inequality is introduced. In addition, the closeness of solutions for the discrete fractional-order systems with impulses and the averaged discrete fractional-order systems with impulses is derived. Finally, three examples are provided to illustrate the efficiency of our main results.
Argon metastable density and temperature of a 94 GHz microplasma
Authors: Navarro Rafael , Hopwood Jeffrey
Published: January 2024

Laser diode absorption spectroscopy is used to experimentally measure Ar(1s5) metastable density and translational gas temperature within a 94 GHz microplasma. A square two-dimensional photonic crystal (PhC) at this resonance frequency serves to ignite and sustain the plasma from 20 to 200 Torr (2.7 × 103–2.7 × 104 Pa) by using millimeter wave power from 300 to 1000 mW. Metastable density within the plasma is estimated from the absorption line shape of the laser traversing the PhC. The metastable density reaches an order of 1019 m−3 at lower pressure and decreases as pressure increases. From the Lorentzian line shape of the absorption profile at 811.53 nm, the gas temperature is extracted and found to increase from 500 K at 20 Torr to 1300 K at 200 Torr. These data are analyzed and compared with a zero-dimensional plasma model and with previous experimental plasma results at 43 GHz.
Optically transparent wideband metamaterial absorber based on equivalent aperture and characteristic mode analysis
Authors: Zheng Qi , Qi Jingjing , Ma Jinyu , PourMohammadi Peyman , Li Qiwei
Published: January 2024

In this work, a low-profile optical transparent wideband metamaterial absorber based on radiation–absorption reciprocal theory is proposed. The top layer and bottom layer are composed of indium tin oxide–polyethylene terephthalate films, and the middle layer is a transparent substrate polymethyl methacrylate. The method of transparent wideband absorption using reciprocal theory is proposed to guide the design. Based on characteristic mode analysis and calculated equivalent aperture efficiency, the absorber consisting of composite resonators is analyzed and designed. The equivalent circuit model and surface current distributions are studied to verify the design. The numerical results show that high absorption of greater than 90% in the frequency range of 5.7–16.4 GHz is obtained. A wideband absorption rate of greater than 80% at a 60° incident angle under TM polarization and an absorption rate of greater than 65% at a 60° incident angle under TE polarization are obtained. The proposed design has the advantages of broadband absorption, polarization insensitivity, light transmittance of more than 70%, and compact structure, which can be applied to special scenes that require optical transparency, such as anechoic chamber glass and cockpit glass.
Subcoercive field dielectric response of 0.5(Ba0.7Ca0.3TiO3)-0.5(BaZr0.2Ti0.8O3) thin film: Peculiar third harmonic signature of phase transitions and residual ferroelectricity
Authors: Nadaud Kevin , Nataf Guillaume F. , Jaber Nazir , Bah Micka , Negulescu Béatrice , Andreazza Pascal , Birnal Pierre , Wolfman Jérôme
Published: January 2024

Subcoercive field non-linearities in 0.5(Ba0.7Ca0.3TiO3)-0.5(BaZr0.2Ti0.8O3) (BCTZ 50/50) thin film elaborated using pulsed laser deposition are studied using permittivity and phase angle of the third harmonic measurements as a function of the AC measuring field EAC and temperature. The global phase transition temperature Tmax for which the permittivity is maximum, decreases from 330 to 260 K when EAC increases. Rayleigh analysis of the AC field dependence of the relative permittivity shows a regular decrease in the domain wall motion contributions as temperature increases up to Tmax and an even more pronounced decrease above Tmax. This measurement reveals that the ferroelectric behavior subsists 70 K above the global phase transition. The phase angle of the third harmonic at temperatures below 275 K is characteristic of a conventional ferroelectric and from 275 K to Tmax=330 K of a relaxor. Above Tmax, the thin film exhibits a peculiar phase angle of the third harmonic, which consists of −180°→−225°→+45°→0° instead of the −180°→−90°→0° found for relaxor. This peculiar behavior is observed only on heating and is tentatively attributed to changes in the correlations between polar nanoregions.
Resistive instabilities in general toroidal plasmas with neoclassical bootstrap currents
Authors: Shi Tonghui , Shen B. , Wan B. N.
Published: January 2024

In this work, linear neoclassical resistive instabilities are investigated in general toroidal plasmas using standard perturbation theory. Using a neoclassical fluid model, we derive the singular layer equations modified by bootstrap currents and also obtain the dispersion relation of the resistive interchange mode and the neoclassical tearing mode (NTM), respectively. Additionally, we determine the stability criteria DRbs and Δcbs for bootstrap current-modified resistive modes. The resistive interchange mode is stable when DRbs<0 and the NTM is stable when Δ′<Δcbs, where Δ′ is the stability index of the tearing mode. It is found that, in tokamak plasmas with a positive magnetic shear, bootstrap currents have a destabilizing effect on resistive interchange modes, which not only increases the value of the stability criterion (DRbs) but also enhances the growth rate. In addition, bootstrap currents have a stabilizing effect on the growth rate of the NTM in a low growth rate region. However, bootstrap currents can also decrease the critical value Δcbs. In plasmas with negative magnetic shear, the opposite holds. Furthermore, the coupling effect between bootstrap currents and Pfirsch–Schlüter currents via magnetic field curvature is determined for the first time in this work. This coupling always has a stabilizing influence on the resistive interchange mode and can increase the value of Δcbs. The coupling is also independent of the sign of the magnetic shear and can be enhanced in low-aspect-ratio tokamaks (such as spherical tokamaks) or in plasma regions with low magnetic shear (as used in ITER hybrid scenarios). Our results are valid for low-n resistive instabilities in toroidal plasmas with arbitrary aspect ratios and β, where n is the toroidal mode number and β represents the ratio of the plasma pressure to the toroidal magnetic pressure. Overall, this investigation has broad parametric applications and deepens our understanding of the physical mechanisms underlying the influence of neoclassical effects on resistive instabilities.
High-performance solar-blind photodetector based on amorphous BN in harsh environment operations
Authors: Chen Le , Tai Jiajin , Wang Deyu , Wang Shuo , Liang Hongwei , Yin Hong
Published: January 2024

High-performance solar-blind photodetectors capable of operating in extreme environments are desirable for a wide range of applications, such as engine control, down hole drilling, space exploration, and environmental monitoring. Boron nitride (BN), with an ultrawide bandgap and high band edge absorption coefficient, is especially suitable for such application scenarios owing to its chemical and structural stability at high temperatures and radiative conditions, which, however, in turn, brings difficulties in synthesis of large-area continuous single crystalline BN. Here, we report highly robust solar-blind photodetectors based on amorphous BN (a-BN) films that can operate at high temperatures and high electric fields. The a-BN films are dense and uniform, grown at 500 °C using dual beam-assisted deposition method. The a-BN-based photodetectors exhibit high performance with a responsivity of 0.56 mA/W at 20 V under UV illumination of 222 nm and a high rejection ratio (R222 nm/R295 nm > 200 and R222 nm/R315 nm > 500). More importantly, these photodetectors demonstrate excellent responsivity and stability at high temperatures up to 500 K and high bias of 200 V without breakdown. The photocurrent mechanism at elevated temperatures is analyzed by temperature-dependent decay time of the temporal response, showing the electron–phonon interaction and self-trapped holes are dominant. Our work suggests that the deposition of such a-BN films offers a promising strategy toward highly environment-resistant solar-blind photodetectors.