bluuebunny/crossref_metadata_2025 huggingface dataset:
Characterization of electromigration-induced short-range stress development in Al(0.25 at. % Cu) conductor line
Authors: Wang P.-C. , Cavanagh K. T. , Gordineer J. S. , Caprotti N. M.
Published: January 2024

Scanning x-ray microbeam topography and fluorescence experiments were conducted in situ to study the electromigration behavior of a 0.5 μm thick, 10 μm wide, and 200 μm long Al(0.25 at. % Cu) conductor line with 1.5 μm-thick SiO2 passivation on a single crystal Si substrate. The strain sensitivity of x-ray topography measurement allowed detailed examination of the electromigration-induced stress distribution and evolution in the conductor line in response to the depletion of Cu solute early in the electromigration process. Upon electromigration at 0.4 MA/cm2 and 303 °C, a short-range stress gradient was quickly induced by Al migration in the Cu-depleted cathode region to counteract further Al flow. The stress gradient was fully developed during the 5.3 h incubation time, extending over the critical Blech length of about 66 μm from the cathode end. Plastic deformation then occurred at the downstream end of the Cu-depleted region. The preferential electromigration of Cu did not cause detectable stress change outside the Cu-depleted region, except for the significant stress development from the Al2Cu precipitation at the anode end which appeared to initiate the fracture in the passivation. Preliminary finite difference modeling was undertaken to simulate the experimental observations, from which important parameters dictating electromigration in Al(Cu) line were extracted: an apparent effective valence of −5.6 and −1.9 for Cu and Al in Al(Cu), respectively, and a critical Cu concentration of 0.16 at. % above which Al grain boundary diffusion is effectively blocked.
Metastable marvels: Navigating VO2 polymorphs for next-gen electronics and energy solutions
Authors: Vishwakarma Neetu , Remadevi Abhijith Ambadi , Kumar Deepak , Solanki Ankur , Rana Abhimanyu Singh , Srivastava Amar
Published: January 2024

VO2 polymorphs present a unique opportunity to unravel diverse electronic properties possessed by their metastable phases. A highly reproducible, single-phase, and inexpensive synthesis method is challenging for obtaining VO2 polymorphs. Recent years have witnessed some exciting success in the growth and application of a wide range of VO2 polymorphs. This comprehensive review article delves into different polymorphs, including VO2(x) (x = A, B, M, R, C, P, and D), and investigates their distinct physical attributes. The primary focus of this article centers on providing a thorough overview of the recent progress made in stabilizing VO2(A) and VO2(B) polymorphs, emphasizing the significance of the coexistence of nanodomains at the film–substrate interface in stabilizing specific metastable phases. Additionally, the review article delves into advancements in understanding the phase transition mechanism, adjusting the order parameter in resistivity, and modifying the metal–insulator transition (MIT) temperature through doping. It also summarizes the structural, optical, electronic, and interface properties of these polymorphs and highlights their potential applications in next-generation electronic devices, particularly in the fields of sensing and energy storage.
Direct numerical simulation of turbulence amplification in a strong shock-wave/turbulent boundary layer interaction
Authors: Kang Yujoo , Lee Sang
Published: January 2024

In this study, the turbulence amplification mechanism within the strong shock-wave/turbulent boundary layer interaction is investigated using direct numerical simulation (DNS) over a 24° compression ramp with Mach 2.9 flow. A new in-house solver based on the compact finite difference scheme is introduced, and its accuracy is validated by comparing the flow statistics with existing DNS and experimental data. Within the DNS findings, two distinct turbulence kinetic energy (TKE) hotspots are identified. In contrast to previous studies, this study sheds light on shocklets, characterized by mid-frequency features, as a key factor contributing to the second TKE amplification, which occurs near the reattachment point. Streamline coordinate analysis reveals that shear effects dominate TKE production over the flow deceleration effect in the shock-wave/turbulent boundary layer interaction. The shear effect induced by the rolling up of the boundary layer initiates the first TKE amplification near the wall region in proximity to the separation point, followed by flow deceleration due to the main shock wave contributing to TKE generation. The initial detachment of the shear layer enhances the shear contribution. While TKE decreases above the separation bubble due to the positive mean velocity gradient, TKE amplifies again due to the flow deceleration caused by the secondary shock wave. In addition, the intermittently spawning shocklets above the bulge structures enhance the shear effect on the TKE production. Moreover, the generated TKE subsequently transfers to the local pressure minimum line, created by the bulges effect, thereby establishing a spatially converged maximum TKE line.
An Assessment of Reproduction of ΔrHo, ΔrCpo, ΔrVo for Water Ionization with Existing Formulations for the Ionization Constant of Water
Authors: Plyasunov Andrey V. , Bugaev Ilya A.
Published: January 2024

Two correlations for the ionization constant of water, log10 Kw, over extended temperature and pressure/density ranges have been proposed in the literature: the Marshall–Franck and Bandura–Lvov formulations. The question remains how well these correlations reproduce the experimental values of ΔrHo, ΔrCpo, and ΔrVo, i.e., the standard changes of the enthalpy, heat capacity, and volume of reaction of water ionization. The answer to this question is the main goal of this communication. First, the analytical expressions for calculating ΔrHo, ΔrCpo, and ΔrVo were derived for the Marshall–Franck and Bandura–Lvov models. Then the calculated values of ΔrHo, ΔrCpo, and ΔrVo were compared with the experimental results from the literature. Although the performance of both correlating models can be termed satisfactory, they do not reproduce existing ΔrHo, ΔrCpo, and ΔrVo data within their expected uncertainties, contrary to the situation with log10 Kw. On the other hand, it appears that the potential for the quantitative reproduction of ΔrHo, ΔrCpo, and ΔrVo exists. It is suggested that the ΔrHo, ΔrCpo, and ΔrVo data should be included in the dataset for the global fit of data when developing formulations for log10 Kw.
Massively parallel implementation of gradients within the random phase approximation: Application to the polymorphs of benzene
Authors: Stein Frederick , Hutter Jürg
Published: January 2024

The Random-Phase approximation (RPA) provides an appealing framework for semi-local density functional theory. In its Resolution-of-the-Identity (RI) approach, it is a very accurate and more cost-effective method than most other wavefunction-based correlation methods. For widespread applications, efficient implementations of nuclear gradients for structure optimizations and data sampling of machine learning approaches are required. We report a well scaling implementation of RI-RPA nuclear gradients on massively parallel computers. The approach is applied to two polymorphs of the benzene crystal obtaining very good cohesive and relative energies. Different correction and extrapolation schemes are investigated for further improvement of the results and estimations of error bars.
Atomic-scale investigation of γ-Ga2O3 deposited on MgAl2O4 and its relationship with β-Ga2O3
Authors: Tang Jingyu , Jiang Kunyao , Xu Chengchao , Cabral Matthew J. , Xiao Kelly , Porter Lisa M. , Davis Robert F.
Published: January 2024

Nominally phase-pure γ-Ga2O3 was deposited on (100) MgAl2O4 within a narrow temperature window centered at ∼470 °C using metal-organic chemical vapor deposition. The film deposited at 440 °C exhibited either poor crystallization or an amorphous structure; the film grown at 500 °C contained both β-Ga2O3 and γ-Ga2O3. A nominally phase-pure β-Ga2O3 film was obtained at 530 °C. Atomic-resolution scanning transmission electron microscopy (STEM) investigations of the γ-Ga2O3 film grown at 470 °C revealed a high density of antiphase boundaries. A planar defect model developed for γ-Al2O3 was extended to explain the stacking sequences of the Ga sublattice observed in the STEM images of γ-Ga2O3. The presence of the 180° rotational domains and 90° rotational domains of β-Ga2O3 inclusions within the γ-Ga2O3 matrix is discussed within the context of a comprehensive investigation of the epitaxial relationship between those two phases in the as-grown film at 470 °C and the same film annealed at 600 °C. The results led to the hypotheses that (i) incorporation of certain dopants, including Si, Ge, Sn, Mg, Al, and Sc, into β-Ga2O3 locally stabilizes the “γ-phase” and (ii) the site preference(s) for these dopants promotes the formation of “γ-phase” and/or γ-Ga2O3 solid solutions. However, in the absence of such dopants, pure γ-Ga2O3 remains the least stable Ga2O3 polymorph, as indicated by its very narrow growth window, lower growth temperatures relative to other Ga2O3 polymorphs, and the largest calculated difference in Helmholtz free energy per formula unit between γ-Ga2O3 and β-Ga2O3 than all other polymorphs.
Intrinsic insulating transport characteristics in low-carrier density EuCd2As2 films
Authors: Nishihaya Shinichi , Nakamura Ayano , Ohno Mizuki , Kriener Markus , Watanabe Yuto , Kawasaki Masashi , Uchida Masaki
Published: January 2024

Searching for an ideal magnetic Weyl semimetal hosting only a single pair of Weyl points has been a focal point for systematic clarification of its unique magnetotransport derived from the interplay between topology and magnetization. Among the candidates, triangular-lattice antiferromagnet EuCd2As2 has been attracting special attention due to the prediction of the ideal Weyl semimetal phase in the ferromagnetic state; however, transport properties of low-carrier density samples have remained elusive. Here, we report molecular beam epitaxy growth of EuCd2As2 films, achieving low-hole density in the range of 1015–1016 cm−3 at low temperature. Transport measurements of such low-carrier density films reveal an insulating behavior with an activation gap of about 200 meV, which persists even in the field-induced ferromagnetic state. Our work provides an important experimental clue that EuCd2As2 is intrinsically insulating, contrary to the previous prediction.
Increase in the effective viscosity of polyethylene under extreme nanoconfinement
Authors: Ren Tian , Hinton Zachary R. , Huang Renjing , Epps Thomas H. , Korley LaShanda , Gorte Raymond J. , Lee Daeyeon
Published: January 2024

Understanding polymer transport in nanopores is crucial for optimizing heterogeneously catalyzed processes in polymer upcycling and fabricating high-performance nanocomposite films and membranes. Although confined polymer dynamics have been extensively studied, the behavior of polyethylene (PE)—the most widely used commodity polymer—in pores smaller than 20 nm remains largely unexplored. We investigate the effects of extreme nanoconfinement on PE transport using capillary rise infiltration in silica nanoparticle packings with average pore radii ranging from ∼1 to ∼9 nm. Using in situ ellipsometry and the Lucas–Washburn model, we discover a previously unknown inverse relationship between effective viscosity (ηeff) and average pore radius (Rpore). Additonally, we determine that PE transport under these extreme conditions is primarily governed by physical confinement, rather than pore surface chemistry. We refine an existing theory to provide a generalized formalism to describe the polymer transport dynamics over a wide range of pore radii (from 1 nm and larger). Our results offer valuable insights for optimizing catalyst supports in polymer upcycling and improving infiltration processes for nanocomposite fabrication.
A repetitive frequency square wave generator based on Blumlein pulse forming network and pseudospark switch
Authors: Yuan Qi , Liu Sheng , Sun Guoxiang , Xue Haorui , Ding Weidong , Wan Zhenbo , Cheng Yuchen , Ren Linyuan , Wang Yanan
Published: January 2024

The Blumlein pulse forming network (PFN) has widely been used in pulsed power technology to generate square waves with short pulse widths. In this paper, we developed a repetitive frequency square wave generator based on Blumlein PFN and pseudospark switch (PSS). A Blumlein PFN with unequal capacitances has been proposed, and the PFN parameters have been optimized for better output waveforms. A single-gap PSS with a withstand voltage of 40 kV and a repetitive frequency of 100 Hz has been designed to switch the Blumlein PFN. The experiment results show that the square wave generator can output pulses with a voltage of 26 kV, a rise time of 25 ns, and a pulse width of 90 ns on a matched load of 11 Ω. It has operated steadily for 10 h with a repetitive frequency of 100 Hz, and the jitter remains at around 1 ns after 1.05 × 106 shots.
Flame stabilization characteristics in the supersonic combustor based on a circular cross-section strut
Authors: Li Menglei , An Bin , Sun Mingbo , Li Peibo , Wang Yanan , Liang Changhai , Wang Jiaoru , Chen Jikai , Yao Yizhi
Published: January 2024

Flame stabilization characteristics in the supersonic combustor with a circular cross-section strut were experimentally investigated. The Mach number, stagnation pressure, and stagnation temperature of the inflow were 2.52, 1.60 MPa, and 1486 K, respectively. Compared to the wedge-shaped recirculation flow at the base of the rectangular cross-section strut, the conical recirculation flow at the base of the circular cross-section strut possessed a more favorable geometry characterized by a longer length, a larger volume, and a small surface. When fueled by hydrogen, the combustor equipped both with a circular cross-section strut and a rectangular cross-section strut could achieve self-sustaining combustion. In the tests with equivalence ratios of 0.08 and 0.12, the time-averaged flame chemiluminescence intensity in the combustor with a circular cross-section strut was higher than its counterpart in the combustor with a rectangular cross-section strut by 80% and 53%, respectively. Nevertheless, the standard deviations of the flame chemiluminescence intensities showed an opposite trend. Therefore, the reaction zone downstream of the circular cross-section strut was more vigorous and stable. When both kerosene and hydrogen were supplied to the combustor, these two struts failed to stabilize the flame. Although an unsteady hydrogen–kerosene flame was witnessed in the combustor, it extinguished within 2 ms because the recirculation flow at the base of the strut was too small. Shock wave generators were employed to enhance the flame stabilization ability of the strut with a circular cross section. The experimental results suggested that shock wave generators significantly enlarged the recirculation flow and created a region with high temperature and high pressure. The self-sustaining hydrogen–kerosene flame was achieved in the combustor equipped with shock wave generators.
Multi-phase retrieval of methane hydrate in natural sediments by cryogenic x-ray computed tomography
Authors: Takeya Satoshi , Hachikubo Akihiro , Sakagami Hirotoshi , Minami Hirotsugu , Yamashita Satoshi , Hirano Keiichi , Hyodo Kazuyuki , Yoneyama Akio
Published: January 2024

In this study, we observed natural methane (CH4) hydrate sediments, which are a type of unconventional natural gas resources, using x-ray computed tomography (CT). Because CH4 hydrates are formed by hydrogen bonding of water molecules with CH4, material decomposition becomes challenging when CH4 hydrates coexist with liquid or solid water in natural sediments. Tri-contrast (absorption, refraction, and scattering) imaging was performed via diffraction enhanced x-ray CT optics using monochromatic synchrotron x rays. The quantitative characterization of the contrast changes successfully enabled the decomposition of CH4 hydrates coexisting with frozen seawater (ice) in natural sediments obtained from the Okhotsk Sea. This study reveals complementary structural information about the microtexture and spatial relation among CH4 hydrates, ice, and pores by utilizing the distinct physical properties of x rays when passing through the materials. These results highlight the exceptional capabilities of high-resolution multicontrast x-ray tomography in materials science and geoscience applications.
Transfer of Cotula alpina to the genus Leptinella (Asteraceae: Anthemideae)
Authors: Schmidt-Lebuhn Alexander N. , Grealy Alicia
Published: January 2024

Tribe Anthemideae (Asteraceae) is represented in Australia by only nine indigenous species of Cotula and Leptinella. The generic placement of Cotula alpina (Hook.f.) Hook.f. is considered problematic, because it shares the stoloniferous and scapose habit of Leptinella, but lacks corollas in female florets, a trait traditionally considered defining of Cotula. A previous phylogenetic analysis of Leptinella using ITS and chloroplast data showed that the species nested in that genus, but some uncertainty remained because of incomplete sequence data and missing cytological information, and no taxonomic change was made. Here, we use target-capture data from three different sequencing initiatives to reconstruct a phylogeny of Australian native and introduced Anthemideae to resolve this outstanding question. We confirm previous results with a high degree of support and formally transfer Cotula alpina to the genus Leptinella. A lectotype is selected for the basionym, Ctenosperma alpinum Hook.f.
Decoupled evolution of the
Sex Peptide
gene family and
Sex Peptide Receptor
in Drosophilidae
Authors: Hopkins Ben R. , Angus-Henry Aidan , Kim Bernard Y. , Carlisle Jolie A. , Thompson Ammon , Kopp Artyom
Published: January 2024

Across internally fertilising species, males transfer ejaculate proteins that trigger wide-ranging changes in female behaviour and physiology. Much theory has been developed to explore the drivers of ejaculate protein evolution. The accelerating availability of high-quality genomes now allows us to test how these proteins are evolving at fine taxonomic scales. Here, we use genomes from 264 species to chart the evolutionary history of Sex Peptide (SP), a potent regulator of female post-mating responses in
Drosophila melanogaster
. We infer that
SP
first evolved in the
Drosophilinae
subfamily and has since followed markedly different evolutionary trajectories in different lineages. Outside of the
Sophophora
–
Lordiphosa
,
SP
exists largely as a single-copy gene with independent losses in several lineages. Within the
Sophophora
–
Lordiphosa,
the
SP
gene family has repeatedly and independently expanded. Up to seven copies, collectively displaying extensive sequence variation, are present in some species. Despite these changes,
SP
expression remains restricted to the male reproductive tract. Alongside, we document considerable interspecific variation in the presence and morphology of seminal microcarriers that, despite the critical role SP plays in microcarrier assembly in
D. melanogaster
, appears to be independent of changes in the presence/absence or sequence of SP. We end by providing evidence that
SP
’s evolution is decoupled from that of its receptor,
Sex Peptide Receptor
, in which we detect no evidence of correlated diversifying selection. Collectively, our work describes the divergent evolutionary trajectories that a novel gene has taken following its origin and finds a surprisingly weak coevolutionary signal between a supposedly sexually antagonistic protein and its receptor.
Conceptions of the make-up of a human person in Ewe
Authors: Ameka Felix K.
Published: January 2024

Humans everywhere construct ethnopsychological models of
a person which involves a physical body and non-physical aspects. There is
variation in how the non-physical parts of a person are construed.
Invariably, it is assumed that this other part is “invisible inside” (Goddard, 2018, p. 168; Levisen, 2017; Peeters, 2019a). The
question of what the components of a human person in African culture(s) are
has been discussed, and debated in the literature (see e.g., Cotzee &
Roux, 2004). In this paper, I examine the conceptual model of a person in
Ewe communities of practice in West Africa through the prism of language and
the meanings of the terms for the ethnopsychological constructs of a
person.
Perception and expression of color among the Wolof of Senegal
Authors: Sall Adjaratou Oumar
Published: January 2024

The analysis and description of color terms has
re-emerged at the center of discussions in contemporary
anthropological linguistic research (based on well-established previous
studies over the past decades). However, work on color terms is still
lacking in most West African linguistic research, particularly in Senegal.
Wolof, a lingua franca spoken mainly in Senegal, has three basic colors used
with adverbs that are never used in other contexts, namely
ñuul ‘black’, ñuul kukk ‘extremely
black’, weex ‘white’, weex tàll ‘extremely
white’, xonq ‘red’ and xonq coyy
‘extremely red’, around which gravitate other shades of color whose terms
are taken from the surrounding vocabulary. The aim of this chapter is first
to present the color concepts and their “shades” in Wolof and to discuss the
question of the morphosyntactic encoding of color terms in linguistic
constructions. We will also consider their classification on the basis of
their semantic properties and occurrence in idiomatic expressions. Finally,
we will show how the community identifies itself through colors and what
symbolic representations of colors exist in the Wolof-speaking
community.
The narrative of a witness
Authors: Rüsch Maren
Published: January 2024

On a regular basis, the news and other shows and
documentaries on East African television feature various stories not only
about events in politics and society, but also of personal fates related to
them. In addition to the presenters, citizens of East African countries
share their perspectives on how they experienced events. This paper focuses
on the way in which these speakers tell their stories on a Kenyan TV show.
It will show how the common ritual oral tradition in Swahili, also
well-established in everyday conversation, is recontextualized in the media
and therefore brought from the ritual frame to the digital context, where it
is supposed to fulfill a particular purpose in favor of the TV program.
Therefore, the presenters instrumentalize the narratives’ inherent
linguistic practices applied by their witnesses to engage viewers in their
program.
Synthesis Methods and Property Control of Two-Dimensional Magnetic Materials
Authors: Li 李 Ming-Shuang 明爽 , Li 李 Hui-Min 惠敏 , Liu 刘 Song 松
Published: January 2024

Two-dimensional (2D) magnetic materials have been demonstrated to have excellent chemical, optical, electrical, and magnetic properties, particularly in the development of multifunctional electronic and spin electronic devices, showcasing tremendous potential. Therefore, corresponding synthesis techniques for 2D magnetic materials that offer high quality, high yield, low cost, time-saving, and simplicity are highly desired. This review provides a comprehensive overview of recent research advances in preparation of magnetic 2D materials, with a particular focus on the preparation methods employed. Moreover, the characteristics and applications of these magnetic materials are also discussed. Finally, the challenges and prospects of synthesis methods for magnetic 2D materials are briefly addressed. This review serves as a guiding reference for the controlled synthesis of 2D magnetic materials.
Assessing the potential of using a virtual Veselago lens in quantitative microwave imaging
Authors: Eini Keleshteri Marzieh , Okhmatovski Vladimir , Jeffrey Ian , Bevacqua Martina Teresa , LoVetri Joe
Published: January 2024

This study explores the potential of implementing the focusing properties of a virtual ideal Veselago lens within a standard free-space microwave imaging scenario. To achieve this, the virtual lens is introduced as an inhomogeneous numerical background for the inverse source problem. This numerical Vesealgo lens is incorporated into the incident and scattered field decomposition, resulting in a new data equation that involves the Veselago lens Green’s function. In addition to the contrast sources within the object-of-interest, the lens introduces virtual contrast sources along the lens boundaries that depend on the total tangential magnetic field. It is shown that a surface integral contribution that takes into account these surface contrast sources must be added to the collected free-space data before one can invert using the well-conditioned Veselago lens inversion operator. A preliminary investigation of the accuracy to which this surface integral contribution must be computed is performed using additive Gaussian noise. Results show that an error of less than one percent is required to achieve imaging performance similar to utilizing an actual Veselago lens. All results are performed within a 2D simulation environment.
On inertial iterated Tikhonov methods for solving ill-posed problems
Authors: Rabelo J C , Leitão A , Madureira A L
Published: January 2024

In this manuscript we propose and analyze an implicit two-point type method (or inertial method) for obtaining stable approximate solutions to linear ill-posed operator equations. The method is based on the iterated Tikhonov (iT) scheme. We establish convergence for exact data, and stability and semi-convergence for noisy data. Regarding numerical experiments we consider: (i) a 2D inverse potential problem, (ii) an image deblurring problem; the computational efficiency of the method is compared with standard implementations of the iT method.
A novel epidemiologically informed particle filter for assessing epidemic phenomena. Application to the monkeypox outbreak of 2022
Authors: Papageorgiou Vasileios E , Kolias Pavlos
Published: January 2024

Contagious diseases are constantly affecting more and more people every day, resulting in widespread health crises especially in developing nations. Previous studies have developed deterministic and stochastic mathematical models to investigate the spread of epidemics. In the present study, a hybrid particle filtering epidemiological model is proposed, which combines the elements of a deterministic susceptible-exposed-infectious-recovered-deceased model with the inclusion of stochastic and penalty factors, in order to efficiently evaluate the dynamics of the disease. The inclusion of penalty factors stands out as the main novelty of the proposed methodology, guaranteeing estimations that align with the unique aspects of the examined natural phenomenon. The model is applied to the monkeypox data of the United States from 25 June to 21 November 2022. Our approach is compared to four alternatives, corresponding to deterministic and stochastic approaches that are associated with either fixed or time-varying parameters. In all cases, the particle filtering models displayed better characteristics in terms of infectious cases and deaths compared to their deterministic counterpart. The final version of the proposed epidemiologically informed particle filtering model exhibited significant potential and provided the best fitting/predictive performance compared to other examined methodologies. The predictive effectiveness of the proposed methodology has been thoroughly evaluated across various time intervals. Moreover, the inclusion of additional penalty factors in the weight computation procedure, assists in reducing fitting and prediction errors while simultaneously providing increased likelihood estimates. This modeling approach can be readily applied to other epidemics, both existing and emerging, where uncertainties in system dynamics and real-time observations hinder the accurate capture of the epidemic’s progression.
Prospects and challenges for all-optical thermal management of fiber lasers
Authors: Ballato John , Dragic Peter D , Digonnet Michel J F
Published: January 2024

It is hard to overstate the utility of lasers in modern technology. Optical-fiber-based lasers are of particular value thanks to their combination of small form factors, afforded by the coilability of the thin strands of fiber, and high beam-quality output. The optical fiber geometry also possesses a relatively high surface-area-to-volume ratio, rendering thermal management somewhat more straightforward than in other bulk laser types. Regardless, the generation of heat during the lasing process can still be problematic for a myriad of reasons, and conventional methods of thermal management do not comport with the potential compactness and elegance of fiber lasers as technological solutions. This Perspective summarizes recent advances in glass science and optical fiber engineering to support the provocative premise that heat generation in future laser systems can be entirely managed by a combination of fiber materials and novel laser physics. Letting the fiber manage heat itself would have significant impacts on enhancing system performance while greatly reducing size, weight, power-consumption, and cost.
Deep learning assisted pressure measurements using femtosecond laser-induced grating scattering technique
Authors: Zhao Tongxun , Ding Pengji , Wang Yishan , Yang Renjun , Yan Sijie , Zhuzou Mingyang , Sun Shaohua , Liu Zuoye , Hu Bitao
Published: January 2024

The femtosecond laser-induced grating scattering (fs-LIGS) technique has recently been developed and applied for temperature and pressure measurements. In this work, we combined deep learning with the fs-LIGS technique to predict the gas-phase pressure from raw signals without data post-processing. Two deep learning models, a fully connected neural network and a convolutional neural network, were trained to master the hidden relationship between the features of the raw signal traces and the corresponding pressure under which the signal was recorded. Accurate pressure predictions by both models were achieved as mean percentage errors in model-predicted pressures compared to actual values within −4%–2%. These results suggest the feasibility of combining the deep-learning concept with the fs-LIGS technique for instantaneous pressure determination. Given the proper training of the models, this strategy could be extended to the simultaneous measurement of multiple thermodynamic quantities in real-time combustion and reacting flow diagnostics.
Time-varying digital coding of induced-magnetism Huygens’ metasurfaces for flexible and continuous control of harmonics
Authors: Zhu Hongyu , Qiu Chunqiao , Li Feng , Wu Chao , Liao Leng , Zhang Zhengren
Published: January 2024

Time-varying digital coding metasurfaces have garnered significant attention due to their ability to achieve flexible and continuous control over harmonics through the flexible design of coding sequences. These metasurfaces have important applications in wireless communications, radar detection, and biomonitoring. However, the majority of existing time-varying digital coding metasurfaces are reflective in design, leading to an inevitable masking effect at the location of the feed source. Therefore, there is an urgent need to explore the design of transmissive time-varying digital coding metasurfaces that enable flexible and continuous control of harmonics. In this study, we propose a transmissive time-varying digital coding metasurface based on the induced-magnetism Huygens’ principle. We conduct a detailed study of the phase modulation theory for flexible and continuous control of harmonics in the time-varying digital coding induced-magnetism Huygens’ metasurface. By precisely modulating the transmission phase difference of this metasurface and introducing time-delay gradients in each column of metasurface units, we achieve flexible and continuous control over harmonics successfully. Our study presents a solution for the design of transmissive time-varying digital coding metasurfaces, enabling flexible and continuous control over harmonics and expanding the application potential of time-varying metasurfaces.
Bands renormalization and superconductivity in the strongly correlated Hubbard model using composite operators method
Authors: Haurie L , Grandadam M , Pangburn E , Banerjee A , Burdin S , Pépin C
Published: January 2024

We use the composite operator method (COM) to analyze the strongly correlated repulsive Hubbard model, investigating the effect of nearest-neighbor hoppings up to fourth order on a square lattice. We consider two sets of self-consistent equations, one enforcing the Pauli principle and the other imposing charge-charge, spin-spin, and pair–pair correlations using a decoupling scheme developed by Roth (1969 Phys. Rev.
184 451–9). We extract three distinct solutions from these equations: COM1 and COM2 by imposing the Pauli principle and one from Roth decoupling. An overview of the method studying the validity of particle-hole symmetry and the Luttinger theorem for each solution is presented. Additionally, we extend the initial basis to study superconductivity, concluding that it is induced by the Van Hove singularity. Finally, we include higher-order hoppings using realistic estimates for tight binding parameters and compare our results with ARPES measurements on cuprates.
On: X-ray diffraction from the electron gas in monatomic metallic hydrogen
Authors: Loa Ingo , Landgren Filip
Published: January 2024

Solid hydrogen is expected to become a monatomic metal under sufficiently high compression. With hydrogen having only a single valence electron and no ion core, the nature of x-ray diffraction patterns from the electron gas of monatomic metallic hydrogen is uncertain, and it is unclear whether they may yield enough information for a crystal structure determination. With emphasis on the Cs-IV-type (

I

4
1

/

a
m
d

) structure predicted for hydrogen at ∼500 GPa, the electron density distributions, zero-point and thermal atomic motion, and x-ray diffraction intensities are determined from first-principles calculations for several candidate phases of metallic hydrogen. It is shown that the electron distribution is much more structured than might be expected from the commonly employed free-electron-gas picture, and in fact more modulated than what is obtained from the superposition of free-atom charge densities. We demonstrate that an identification of the crystal structure of monatomic metallic hydrogen from x-ray diffraction is fundamentally possible and discuss the possibility of single-crystal diffraction from metallic hydrogen. An atomic scattering factor for the hydrogen atom in monatomic metallic hydrogen is constructed to aid the quantitative analysis of diffraction intensities from future x-ray diffraction experiments.
Real-time tunnel lining leakage image semantic segmentation via multiple attention mechanisms
Authors: Tan Yonghui , Li Xiaolong , Lai Jinfu , Ai Jinquan
Published: January 2024

One of the key objectives in tunnel illness detection is identifying tunnel lining leakage, and deep learning-based image semantic segmentation approaches can automatically locate tunnel lining leakage. However, in order to meet the real-time processing needs of professional mobile inspection equipment, existing leakage image segmentation approaches have difficulties in identifying real-time, dealing with voids, and dealing with edge discontinuities in the leaking zone. To address the aforementioned issues, this study introduces the PP-LiteSeg-Attn model, which takes the real-time semantic segmentation model PP-LiteSeg-B as baseline model, and combines the multi-layer CBAM attention mechanism and the CoT attention mechanism. Using the publically available dataset Water-Leakage, we trained and validated the PP-LiteSeg-Attn model, and attained IoU and F1 values of 88.18% and 93.72%, respectively, outperforming similar models in both measures. Extensive experiments show that the segmentation speed of the PP-LiteSeg-Attn model reaches 112.28 FPS, which meets real-time requirements, and that the model can effectively solve problems such as the appearance of voids in the seepage area, discontinuity, and fuzzy segmentation of seepage edges. The PP-LiteSeg-Attn model is better applicable to complicated tunnel settings, offering technical references for real-time diagnosis of tunnel illnesses.
Role of extrinsic factors on magnetoelastic resonance biosensors sensitivity
Authors: Lima Luiza Felippi de , Dutra Roberta , González Diego , Sommer Rubem Luis , Perottoni Cláudio Antônio , Aguzzoli Cesar , Roesch-Ely Mariana
Published: January 2024

Magnetoelastic (ME) resonance devices are attractive for application as biosensors in health-related areas as they allow contactless detection of pathogenic agents with high sensitivity. After functionalization, they offer valuable diagnostic options that promote efficient capture of mass on the sensor surface through biological interactions. ME sensors are also sensitive to external factors such as temperature, magnetic fields, and variations in mass that can arise from processes unrelated to biological interactions, including corrosion and salt crystallization. This article evaluates extrinsic factors that affect the response of ME resonance sensors for diagnostic applications. In particular, the influence of heat treatments, operation temperature, applied DC magnetic field bias, and corrosive environment were studied. The control of all these factors is crucial for the design, fabrication, and functionalization of ME resonance biosensors and for the development of measuring instrumentation and effective measurement protocols. This work established maximum operating temperature and bias field variations to keep the sensor sensitivity. Heat treatment of the sensors before and after coating improved the signal-to-noise ratio and corrosion resistance. Further improvement in corrosion resistance was provided by cathodic protection, which has been proven beneficial for applications of ME resonance sensors in aqueous fluids.
Process monitoring via dependence description based on variable selection and vine copula
Authors: Bai Xinpeng , Qiu Suiqing , Liu Shisong , Li Shaojun
Published: January 2024

Process monitoring is crucial to ensure the safety of industrial processes. Generally, the monitoring process involves all measured variables; however, large industrial processes contain many redundant variables. For a method based on describing the intrinsic correlation relationships among variables, the vine copula-based dependence description (VCDD) method shows significant advantages for describing nonlinear and non-Gaussian processes. However, redundant and irrelevant variables adversely affect the correlation between variables containing the most important information, reducing model performance. The lack of research in this area may substantially weaken the advantages of VCDD for fault monitoring. Therefore, this article introduces a variable selection vine copula dependence description monitoring model. It utilizes known faults as validation data to select the relevant variables for constructing the VCDD model, specifically designed for monitoring known faults. Furthermore, to prevent information loss, the remaining unselected variables are also employed to create a separate VCDD model, dedicated to monitoring unknown faults. The performance of the proposed method is verified by a numerical example, the Tennessee-Eastman process and the Penicillin fermentation process.
Biosynthesized CuO nanoparticles–coated grating sensors for temperature measurement
Authors: Bendigeri H H , Kulkarni Vijay , Jadhav Mangesh S , Lalasangi Anandkumar , Mastiholi Balesh , Kulkarni Sameer , Kumar Jitendra , Prakash Om , Raikar U S
Published: January 2024

In this study, we demonstrate temperature sensing using a fiber Bragg grating (FBG) fixed on a Teflon substrate with a large thermal expansion coefficient. A significant enhancement in sensitivity was achieved by coating the fiber with green synthesized copper oxide nanoparticles. This improvement was characterized by UV–visible spectroscopy, scanning electron microscopy, differential scanning calorimetry, and other techniques. The behavior of the coated materials is unique in their response to thermal stability based on the mode of coating. We have examined the thermal responses of FBG sensors mounted on temperature units on and after coating. The designed sensor is compact, cost effective, and measures temperatures in the range of 25 °C–200 °C. It demonstrated a linear relationship between the wavelength shift and temperature change along with 0.59 pm/ oC enhancement in the sensitivity. However, by optimizing the materials and physical dimensions of FBG, it is possible to increase the range of temperature detection, thereby improving the sensor’s performance. It is observed that the sensitivity of the nanoparticles-coated FBG is better than that of the bare FBG for all temperature ranges.
Shape detection of thin diameter flexible sensors with non-uniform gratings
Authors: Chen Xiangyan , Qian Jinwu , Yu Yingjie , Zhang Yanan , Shen Tingting
Published: January 2024

Flexible intelligent medical device shape feedback has a very important application prospect in intelligent structure detection. Due to the error accumulation effect, the distribution of gratings is also an important factor affecting the reconstruction error of shape sensors. A grating positions optimization method based on the fusion of adaptive mutation particle swarm optimization algorithm and shape reconstruction algorithm is proposed in the paper. The curves with 10 measurement points arranged at a sensing length of 810 mm and 4 measurement points arranged at a sensing length of 200 mm are simulated and calculated. After multiple optimization training, the sparse optimal distribution of gratings with the smallest shape error is obtained. Package sensors with uniform and non-uniform distribution of grating points based on the obtained point positions, and conduct planar shape reconstruction experiments. After multiple shape reconstruction experiments, the shape errors of the sensor shape reconstruction endpoint for uniform gratings are 2.76% and 2.94%, respectively, and the reconstruction accuracy for non-uniform gratings is 1.94% and 2.71%. The optimized shape sensor has good performance, thus proving the effectiveness of the fiber grating sensing grid point optimization method in flexible medical device deformation monitoring.
Design and analysis of a galloping-based piezoelectric energy harvester with coupled magnetism
Authors: Wang Jiawei , Tang Bowen , Tan Wei
Published: January 2024

Wind-induced vibration energy harvesters have attracted increasing attention due to their unique dynamic characteristics and excellent energy harvesting performance. In this study, two types of magnetic energy harvesters, namely the magnetic attraction energy harvester (A-GEH) and the coupled magnetic attraction and repulsion energy harvester (A&R-GEH), were designed and their electromechanical coupling analysis models were established. The results showed that the magnetically coupled energy harvesters can adjust the operating wind speed range and increase the energy harvesting capability by varying the placement of the magnetic poles and the magnetic moment. Furthermore, the established analysis model accurately predicted the results of the wind tunnel experiments. The output power of the energy harvesters was evaluated by illuminating LED bulbs, demonstrating the potential for self-powering small wireless sensors. Under an experimental wind speed of 5.1 m s−1 and a vertical distance Δy = 12 mm between the magnets, the A-GEH and A&R-GEH showed an increase in output power of 356.854% and 365.488%, respectively, compared to a general energy harvester without magnetism. In conclusion, this study provides a framework for the analysis and design of magnetic-coupled wind-induced vibration energy harvesters.
Design and analysis of magnetostrictive two-dimensional kinetic energy harvester
Authors: Liu Huifang , Tong Xiaoyan , Sun Xingwei , Wang Wenguo , Su Liang , Chang Yunlong , Liu Zhanqi
Published: January 2024

Conventional energy harvesters often require high ambient vibration frequencies and can only capture vibration energy in a single direction. To address these issues, this paper designs a magnetostrictive two-dimensional kinetic energy harvester placed under the floor and capable of capturing energy in both vertical and horizontal directions. In order to achieve higher electrical power output at low-frequency input forces, a two-stage force amplification mechanism is designed to amplify the walking kinetic energy of pedestrians and the main parameters of this structure are analyzed and optimized. On the other hand, by constructing different forms of bias magnetic field, the influence of bias magnetic field on the deflection and motion of the internal magnetic domain of Terfenol-D is systematically studied, and the best bias form that can make the material shows the strongest magnetization characteristics is determined. Next, a prototype harvester was built, and an experimental vibration system was set up to test and analyze the output characteristics of the harvester comprehensively. The experimental results show that the harvester produces 21.2 mW of peak output power under sinusoidal excitation at an operating frequency of 4 Hz. Under random excitation, a peak output voltage of 2.64 V and 170 mW peak power was obtained. Under actual pedestrian walking tests, 17.62 mW peak output power is obtained to power low-power devices. The study’s results provide preliminary evidence that the designed magnetostrictive energy harvester can stably harvest kinetic energy from pedestrian walking.
Inkjet printing P(VDF-TrFE-CTFE) actuators for large bending strains
Authors: Sekar S A , Hunt A
Published: January 2024

Additive manufacturing of sensors and actuators together with structural materials and electronics will make it possible to fabricate innovative system designs that are overly laborious to realise with conventional methods. While printing of the structural materials and electronics are advancing fast, the additive manufacturing methods for actuators and sensors are in an earlier stage of development. This research will develop a manufacturing process for entirely inkjet printed electroactive polymer (EAP) actuators basing on the P(VDF-TrFE-CTFE) relaxor ferroelectric polymer and Ag electrodes. The process consists of (1) printing an Ag layer on a polyethylene terephthalate (PET) substrate for the bottom electrode; (2) formulating, printing and annealing a P(VDF-TrFE-CTFE) ink for the EAP layer; and (3) printing and sintering an Ag layer on the plasma-treated EAP surface to form the top electrode. Two actuator variations, addressed as DMC and KM512, are manufactured and characterised by their: (a) response to quasi-static excitation (1 Hz sine wave); (b) hysteresis behaviour; (c) actuation amplitude variation with the input voltage; and (d) frequency response. The 18 mm long actuators showed 91.4 µm (DMC, 200 

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) and 224 µm (KM512, 275 

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) deflections in response to 1 Hz sinusoidal excitation, and 1.10 mm (DMC, 113 Hz, 200 

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) and 1.72 mm (KM512, 114 Hz, 200 

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) deflections in resonant operation. It is 55% more quasi-static strain and 470% more resonant strain than in earlier fully inkjet-printed polyvinylidene fluoride (PVDF) -based actuators, and comparable to similar partially inkjet-printed actuators. This is the first time that inkjet printing of all three layers of a relaxor ferroelectric actuator have been achieved.