bluuebunny/crossref_metadata_2025 huggingface dataset:
Nuclear induction line shape: Non-Markovian diffusion with boundaries
Authors: Niknam Mohamad , Bouchard Louis-S.
Published: January 2024

The dynamics of viscoelastic fluids are governed by a memory function, essential yet challenging to compute, especially when diffusion faces boundary restrictions. We propose a computational method that captures memory effects by analyzing the time-correlation function of the pressure tensor, a viscosity indicator, through the Stokes–Einstein equation’s analytic continuation into the Laplace domain. We integrate this equation with molecular dynamics simulations to derive necessary parameters. Our approach computes nuclear magnetic resonance (NMR) line shapes using a generalized diffusion coefficient, accounting for temperature and confinement geometry. This method directly links the memory function with thermal transport parameters, facilitating accurate NMR signal computation for non-Markovian fluids in confined geometries.
On the interaction of two cavitation bubbles produced at different times: A jet from the primary bubble
Authors: Terasaki Shingo , Kiyama Akihito , Kang Donghyuk , Tomita Yukio , Sato Kotaro
Published: January 2024

The liquid jet formation upon the collapse of two interacting cavitation bubbles is a physics-rich complex problem, which has possible implications such as the membrane sonoporation. In this paper, we employed both experiment and numerical simulations to study the jet behavior in a bubble, which is affected by another one introduced at various time delays. We provided the regime diagram, which shows the transition of the jet direction as a function of time delay and distance between bubbles. The maximum velocity of the jet in the primary bubble was investigated. The highest velocity was achieved when the primary bubble split into two parts upon collapse. It was found that a high curvature on the rim of the collapsing primary bubble causes the lateral pinch-off, leading to the formation of a fast and thin vertical jet approaching the secondary bubble. The results would help design an effective sonoporation system. The physics depicted in this manuscript might also contribute to the deeper understanding of the jet in a bubble interacting with not only another bubble but also other boundaries.
Numerical study of chain-reaction implosions in a spatial array of ceramic pressure hulls in the deep sea using a compressible multiphase flow model
Authors: Sun Shengxia , Zhao Min , Jiang Yuanteng
Published: January 2024

Ceramic pressure hull arrays, which are core components in providing buoyancy to underwater vehicles, are at risk of chain-reaction implosions in deep-sea environments. This study establishes a numerical model for the chain-reaction implosions of ceramic pressure hull arrays. The model is based on the theory of compressible multiphase flow. The structural finite element method combined with the ceramic material failure criterion is used to determine the cause of chain-reaction implosions. Adaptive mesh refinement is adopted to capture the gas–liquid interface accurately. The accuracy of the numerical simulation method for compressible multiphase flow is verified through an implosion experiment involving a single ceramic pressure hull. Subsequently, the simultaneous implosions of an array of ceramic pressure hulls are calculated and investigated. Finally, the chain-reaction implosions of an array of ceramic pressure hulls are calculated using the proposed model. The propagation of the implosion shockwaves and the implosion flow field distribution are analyzed and compared with those of the simultaneous implosion case. The pressure reduction in the flow field caused by the expansion waves of the implosion is found to cause the chain-reaction implosion of neighboring ceramic pressure hulls. In the chain-reaction process, the air converges at the array center, and the implosion shockwaves converge toward the center and overlap, resulting in the largest-amplitude implosion shockwave occurring near the center of the array. This phenomenon is named the converging effect of chain-reaction implosions.
Numerical simulations of a magnonic reservoir computer
Authors: Watt Stuart , Kostylev Mikhail
Published: January 2024

A numerical model for a spin wave delay-line active ring resonator is presented. Spin wave dynamics along a one-dimensional strip of magnetic material are modeled using the nonlinear Schrödinger equation. The equation is solved numerically in Fourier space using the fourth-order Runge–Kutta method and yields qualitative agreement with experimental measurements of spin wave dynamics in two different regimes. The model provides a useful tool for performing experiments based on neuromorphic computing and logic gates in traveling spin wave devices.
Bicontinuous microemulsion in binary blends of complementary diblock copolymers
Authors: Willis J. D. , Matsen M. W.
Published: January 2024

The phase behavior of binary blends of AB diblock copolymers of compositions f and 1 − f is examined using field-theoretic simulations. Highly asymmetric compositions (i.e., f ≈ 0) behave like homopolymer blends macrophase separating into coexisting A- and B-rich phases as the segregation is increased, whereas more symmetric diblocks (i.e., f ≈ 0.5) microphase separate into an ordered lamellar phase. In self-consistent field theory, these behaviors are separated by a Lifshitz critical point at f = 0.2113. However, its lower critical dimension is believed to be four, which implies that the Lifshitz point should be destroyed by fluctuations. Consistent with this, it is found to transform into a tricritical point. Furthermore, the highly swollen lamellar phase near the mean-field Lifshitz point disorders into a bicontinuous microemulsion (BμE), consisting of large interpenetrating A- and B-rich microdomains. BμE has been previously reported in ternary blends of AB diblock copolymer with its parent A- and B-type homopolymers, but in that system the homopolymers have a tendency to macrophase separate. Our alternative system for creating BμE is free of this macrophase separation.
An improved formula for bed-load rate in open channel flows with emergent vegetation
Authors: Wang Xiang , Gualtieri Carlo , Huai Wenxin , Liu Honghua , Yu Songli
Published: January 2024

There is an urgent need to predict the bed-load transport rate in vegetated river ecosystems to support restoration efforts. In response, we have developed a novel model for estimating the effective shear stress acting on the riverbed. This model is based on the energy equation and considers the intrinsic relationship between energy loss in the mean flow and turbulence generated by vegetation in open channel flows with emergent vegetation. Using this bed shear stress model, we assessed the performance of the Meyer-Peter–Müller (MPM) formula in predicting the bed-load transport rate in vegetated flows by comparing it with collected literature experimental data. The results revealed that the MPM formula does not provide accurate predictions. It tends to overestimate the bed-load transport rate when the dimensionless effective shear stress is approximately less than one and underestimate them when the dimensionless effective shear stress is approximately greater than one. This suggests that vegetation enhances and decreases the sediment transport rate when the dimensionless effective shear stress is approximately larger or lower than one, respectively. Consequently, we modified the coefficients of the MPM formula using extensive experimental data, leading to the development of a novel predictive formula for the bed-load transport rate in vegetated flows. This new formula outperforms existing literature equations and is effective for predicting the bedload transport rate, even for umbrella-like vegetation.
A conservative implicit scheme for three-dimensional steady flows of diatomic gases in all flow regimes using unstructured meshes in the physical and velocity spaces
Authors: Zhang Rui , Liu Sha , Chen Jianfeng , Zhuo Congshan , Zhong Chengwen
Published: January 2024

A conservative implicit scheme in the finite volume discrete velocity method framework is proposed for solving the three-dimensional steady flows of molecular gases in all flow regimes from continuum one to free-molecular one. This work is based on the Boltzmann–Rykov model equation, which is a nonlinear relaxation model and can describe the thermodynamic non-equilibrium of diatomic gas flows. The macroscopic equations are solved implicitly together with the Rykov model equation to find a predicted equilibrium distribution first at each iteration step. As a result, the collision term of the Rykov model equation can be discretized in a fully implicit way for fast convergence in all flow regimes. At the cell interface, an asymptotic preserving simplified multi-scale numerical flux is developed to relieve the limitation of grid size and time step in all flow regimes, which can keep the multi-scale property and achieve high computational efficiency. The integral error compensation technique is used to keep the scheme conservative and greatly reduce the number of unstructured discrete velocity space (DVS) meshes. Furthermore, an empirical criterion based on the numerical experiments of the Apollo 6 command module is suggested to guide the generation of three-dimensional unstructured DVS. The accuracy and efficiency of the present method are demonstrated by a number of three-dimensional classic cases, covering different flow regimes.
Dissociation following the Auger decay of xenon difluoride molecules
Authors: Hikosaka Yasumasa
Published: January 2024

This study investigated the dissociation after the Xe 4d Auger decay of weak-bonding XeF2 molecules by multielectron–ion coincidence spectroscopy using a magnetic bottle electron spectrometer. Fragmentations from the XeF22+ states were clarified in the Auger spectra coincident with individual ion species. It was observed that the two-hole population led by the Auger decay was not directly inherited during the fragmentation of XeF22+. Furthermore, the dissociations of XeF23+ states produced by the double Auger decay were investigated.
Linear and nonlinear investigations of the impact of chemical reaction on the thermohaline convection in a permeable layer saturated with Casson fluid
Authors: Yadav Dhananjay , Nair Sanjith Bharatharajan , Awasthi Mukesh Kumar , Ragoju Ravi , Bhattacharyya Krishnendu
Published: January 2024

In this effort, the consequence of chemical reaction on the thermohaline convection in a permeable layer containing Casson fluid is inspected utilizing both linear and nonlinear stability procedures. To model the momentum equation, the Casson fluid version of Darcy's law is utilized. Applying the linear stability concept, the situation for the start of stationary and oscillatory pattern of convective motion is obtained, whereas the convective heat and mass transferences are determined using nonlinear stability theory. It is found that the oscillatory type of convective flow is probable only if the evaluation of the solutal Rayleigh–Darcy number is less than zero. The effect of the chemical reacting factor, the Casson factor, the Lewis number, and the solutal Rayleigh–Darcy number is to hurry the start of convection toward both stationary and oscillatory styles of convection and also surge the size of the convective cells. The convective heat and mass transfers enhance with increasing the Casson factor, the solutal and thermal Rayleigh–Darcy numbers while both decrease with enhancing the heat capacity quotient. The effect of chemical reacting factor is to increase the mass transmission in the system, while it has no effect on the heat transmission. It is also noted that the convective heat and mass transfers in the system enhance nearly 5.4% and 3.8%, respectively, with a 50% increase in the value of Casson factor.
Biomechanical mechanism of noninvasive plaque detection based on multi-sensor fusion
Authors: Zhu Pengrui , Hu Yiran , Shi Bojing , Fan Yubo
Published: January 2024

Plaque can induce stroke and other serious cardiovascular and cerebrovascular diseases. How to diagnose plaque early has important clinical significance. Recently, the conventional detection methods are mainly medical imaging methods such as computed tomography, and there is still a lack of portable nonimaging detection technology or devices that can be used at home. To achieve such plaque detection techniques, possible solutions are based on pulse wave sensors and blood flow sensors to extract plaque signature signals. Elucidating the relationship between the sensing signals of these two types of sensors and changes in hemodynamic parameters caused by plaque is the basis of developing accurate wearable continuous monitoring systems for plaque. In this study, based on the flow–solid interaction effect between the vessel wall and the blood flow, the stenotic vessels induced by plaques were modeled by numerical simulation software, and the distribution patterns of vessel deformation and blood flow velocity near plaques during the cardiac cycle were investigated in detail. By measuring and processing these two simultaneous dynamic signals, a preliminary method of estimating plaque size based on displacement, velocity, and their first-order derivative curves is developed, and the errors are all less than 9.5%. Meanwhile, to explore the relationship between the detected signals from multiple arterial sites and plaques, we investigated the response of carotid, brachial, and radial artery signals to different sizes of plaques using the block parameter model of vascular network, which provides a theoretical basis for the construction of a multi-sensor fusion for noninvasive plaque detection.
Not so fussy after all: Shark Bay mouse (Pseudomys gouldii) recorded using a range of habitat types on Faure Island
Authors: Palmer Bryony Joan , Cowen Saul Jesse , Bourne Amanda Ruth
Published: January 2024

The Shark Bay mouse (SBM; Pseudomys gouldii) was once widespread across south and central Australia. Following European colonisation, SBM declined catastrophically and the only surviving natural population is found on Bernier Island. Several reintroductions of SBM have been attempted but, to date, populations have successfully established on just two Western Australian islands, Faure Island in Shark Bay and North West Island in the Montebello Archipelago. A lack of suitable habitat, particularly dense stands of coastal spinifex (Spinifex longifolius), is thought to have contributed to the failure of the species to establish at some sites. We analysed records of SBM on Faure Island from 2005 to 2023 to assess patterns of detection in different habitat types, including coastal spinifex. SBM were detected in all studied habitat types on Faure Island, suggesting that coastal spinifex may not be essential for the successful reintroduction of the species. Understanding habitat use by SBM on Faure Island may help to inform the selection of future reintroduction sites and the development of future release strategies. This is particularly important in the context of reintroductions to locations within the species’ historical range where coastal spinifex does not occur.
Use of electrolyte and betaine water supplementation to support improved liveweight gain of commercial Pekin ducks exposed to adverse high temperature in the week prior to processing
Authors: Downing J. A.
Published: January 2024

Context Commercial Pekin Ducks housed in conventional open-sided sheds often experience heat stress in summer. Electrolyte or osmolyte supplements can help birds cope under heat stress. Aims To assess the effects of water electrolyte/betaine supplementation or betaine in feed on the growth performance of Pekin ducks exposed to high ambient temperature. Methods Commercial Cherry Valley Pekin ducks were fed diets with a dietary electrolyte balance (DEB) of 160 (L-DEB) or 209 (H-DEB) over Days 15–41 (D15–41) of age. Over D36–41, ducks were provided with water alone or supplemented with betaine in the feed (BF), or betaine and an ‘in-house’ electrolyte (E) formulation at 50%, 100% or 150% (D36–41) or at 100% for only 36 h on D40–41. There were 12 treatments with four replicate pens for each treatment. On D36–41 of age, temperature was increased to 28–32°C for 9 h (from 08:30 hours to 17:30 hours) and then returned to 22–24°C for the remainder of the day. Individual liveweights were taken on D28, D35, D41. During these times, feed intake and water consumption were determined. On D41, one male and one female from each pen were weighed, euthanised and breast muscle was removed and weighed. Birds were collected for commercial processing at 04:00 hours on D42. Key results Over D15–35, the DEB had no effect on bird performance. Over D36–41, for liveweight gain (LWG) there were significant interactions between treatment × week (P < 0.001) and treatment × diet (P = 0.017). Supplements E150 and E100 + 36 h supported LWG more than did other treatments, while treatments BF, E50 and E100 supported higher LWG than in controls. On the L-DEB diet, the control birds had a LWG lower than in other treatments (P < 0.05). On the H-DEB diet, the E50 supplement had highest LWG, but comparable to that in E100 + 36 h. The supplements had no effects on breast muscle yield, weight losses during transport and lairage or processed carcass weights. Conclusions The electrolyte supplements supported higher LWG during exposure to moderately adverse high temperature. Supply for 36 h supported LWG equivalent or better than did other treatments given over 6 days. The benefits could be related to increased water intake and not just electrolyte supply. Implications Water electrolyte plus betaine supplementation supports improved Pekin duck performance during a moderately high temperature challenge.
Self-reported intimate partner violence among men who have sex with men at an urban Australian sexual health clinic
Authors: Boots Georgina , Crozier Brendan , Popovic Gordana , McNulty Anna
Published: January 2024

Background In Australia, 17% of women and 6% of men have experienced intimate partner violence (IPV). Although most IPV research has focused on heterosexual partnerships, studies suggest that men who have sex with men (MSM) may experience IPV at similar or higher rates than those documented among women. IPV may also take different forms among MSM and have different health and social impacts. This study aims to assess the utility of a screening tool for identifying and responding to IPV among MSM attending a sexual health clinic in Sydney, Australia. Methods Between 1 June 2020 and 30 June 2022, MSM clients were screened using standardised questions to identify IPV experienced within the preceding 12 months. Answers to the screening questions were correlated with data collected routinely at the initial clinic visit, including age, employment, country of birth, drug and alcohol use, sexual partner numbers, and any history of sex work, pre-exposure prophylaxis use and HIV status, as well as any bacterial STI diagnosed at the initial visit. Results There were 2410 eligible clients and of these, 2167 (89.9%) were screened during the study period. A total of 64 men (3.0%) (95% CI 2.3–3.8%) reported experiencing physical violence or intimidation in the past 12 months. Controlling for age, men who were born in Australia were 2.03 (95% CI: 1.04–3.01) times more likely to report IPV, and men who had Medicare were 2.43 (95% CI: 0.95–3.90) times more likely to report IPV than those who did not. Those who had ever injected drugs were 5.8 (95% CI: 1.87–9.73) times more likely to report IPV, and men with sexualised drug use were 4.11 (95% CI: 2.03–6.19) times more likely. Those that were employed or studying were 72% (95%CI: 0.13–0.42) less likely to report IPV. Conclusions The prevalence of reported IPV in our study was lower than that reported by others, which may be due to differences in recruitment methods and questions asked. Associations between IPV in MSM and injecting drug use and sexualised drug use highlight that clinicians should be aware of the impact and potential for IPV particularly in those with risk factors.
Selection pressures on evolution of ribonuclease H explored with rigorous free–energy–based design
Authors: Hayes Ryan L. , Nixon Charlotte F. , Marqusee Susan , Brooks Charles L.
Published: January 2024

Understanding natural protein evolution and designing novel proteins are motivating interest in development of high-throughput methods to explore large sequence spaces. In this work, we demonstrate the application of multisite λ dynamics (MSλD), a rigorous free energy simulation method, and chemical denaturation experiments to quantify evolutionary selection pressure from sequence–stability relationships and to address questions of design. This study examines a mesophilic phylogenetic clade of ribonuclease H (RNase H), furthering its extensive characterization in earlier studies, focusing on
E. coli
RNase H (ecRNH) and a more stable consensus sequence (AncCcons) differing at 15 positions. The stabilities of 32,768 chimeras between these two sequences were computed using the MSλD framework. The most stable and least stable chimeras were predicted and tested along with several other sequences, revealing a designed chimera with approximately the same stability increase as AncCcons, but requiring only half the mutations. Comparing the computed stabilities with experiment for 12 sequences reveals a Pearson correlation of 0.86 and root mean squared error of 1.18 kcal/mol, an unprecedented level of accuracy well beyond less rigorous computational design methods. We then quantified selection pressure using a simple evolutionary model in which sequences are selected according to the Boltzmann factor of their stability. Selection temperatures from 110 to 168 K are estimated in three ways by comparing experimental and computational results to evolutionary models. These estimates indicate selection pressure is high, which has implications for evolutionary dynamics and for the accuracy required for design, and suggests accurate high-throughput computational methods like MSλD may enable more effective protein design.
Structure of a tripartite protein complex that targets toxins to the type VII secretion system
Authors: Klein Timothy A. , Shah Prakhar Y. , Gkragkopoulou Polyniki , Grebenc Dirk W. , Kim Youngchang , Whitney John C.
Published: January 2024

Type VII secretion systems are membrane-embedded nanomachines used by Gram-positive bacteria to export effector proteins from the cytoplasm to the extracellular environment. Many of these effectors are polymorphic toxins comprised of an N-terminal Leu-x-Gly (LXG) domain of unknown function and a C-terminal toxin domain that inhibits the growth of bacterial competitors. In recent work, it was shown that LXG effectors require two cognate Lap proteins for T7SS-dependent export. Here, we present the 2.6 Å structure of the LXG domain of the TelA toxin from the opportunistic pathogenStreptococcus intermediusin complex with both of its cognate Lap targeting factors. The structure reveals an elongated α-helical bundle within which each Lap protein makes extensive hydrophobic contacts with either end of the LXG domain. Remarkably, despite low overall sequence identity, we identify striking structural similarity between our LXG complex and PE–PPE heterodimers exported by the distantly related ESX type VII secretion systems of Mycobacteria implying a conserved mechanism of effector export among diverse Gram-positive bacteria. Overall, our findings demonstrate that LXG domains, in conjunction with their cognate Lap targeting factors, represent a tripartite secretion signal for a widespread family of T7SS toxins.
Sm complex assembly and 5′ cap trimethylation promote selective processing of snRNAs by the 3′ exonuclease TOE1
Authors: Ma Tiantai , Xiong Erica S. , Lardelli Rea M. , Lykke-Andersen Jens
Published: January 2024

Competing exonucleases that promote 3′ end maturation or degradation direct quality control of small non-coding RNAs, but how these enzymes distinguish normal from aberrant RNAs is poorly understood. The Pontocerebellar Hypoplasia 7 (PCH7)–associated 3′ exonuclease TOE1 promotes maturation of canonical small nuclear RNAs (snRNAs). Here, we demonstrate that TOE1 achieves specificity toward canonical snRNAs through their Sm complex assembly and cap trimethylation, two features that distinguish snRNAs undergoing correct biogenesis from other small non-coding RNAs. Indeed, disruption of Sm complex assembly via snRNA mutations or protein depletions obstructs snRNA processing by TOE1, and in vitro snRNA processing by TOE1 is stimulated by a trimethylated cap. An unstable snRNA variant that normally fails to undergo maturation becomes fully processed by TOE1 when its degenerate Sm binding motif is converted into a canonical one. Our findings uncover the molecular basis for how TOE1 distinguishes snRNAs from other small non-coding RNAs and explain how TOE1 promotes maturation specifically of canonical snRNAs undergoing proper processing.
La retraducción como práctica arqueológica
Authors: Ortiz García Javier
Published: January 2024

Este artículo aborda de manera teórica y práctica el fenómeno de la retraducción. El estudio propone una aproximación holística de la retraducción, empleando para su desarrollo dos factores esenciales en el proceso retraductor: la frecuencia de la aparición de las retraducciones de una obra determinada y los testimonios de los propios retraductores sobre su trabajo con esa obra. Se emplean cuatro versiones de la novelaMoby-Dick(Melville 1851) publicadas en España en un periodo de ocho años (2007–2014) de las que contamos con testimonios directos de los retraductores en forma de introducciones, publicaciones académicas y divulgativas y correspondencia personal. El cotejo de la frecuencia con que aparecieron esas versiones con las constataciones de los retraductores y los resultados de los análisis de tres ejemplos especialmente seleccionados de esas retraducciones ayuda a subrayar la importancia y la necesidad de la elaboración de estudios sobre la retraducción que vayan más allá de los estudios comparativos de casos.
Mural cells interact with macrophages in the dura mater to regulate CNS immune surveillance
Authors: Min Hyunjung , O’Neil Shane M. , Xu Li , Moseman E. Ashley , Kurtzberg Joanne , Filiano Anthony J.
Published: January 2024

The central nervous system (CNS) tightly regulates access of circulating immune cells. Immunosurveillance is therefore managed in the meninges at the borders of the CNS. Here, we demonstrated that mural cells, which include pericytes and smooth muscle cells, decreased coverage around blood vessels in the dura, the outermost layer of the meninges, and upregulated gene pathways involved in leukocyte migration in presymptomatic experimental autoimmune encephalomyelitis (EAE). Partially depleting mural cells promoted the trafficking of CNS antigen-specific T cells to the dura in a process that depended on resident antigen-presenting cells, thereby increasing susceptibility to passive EAE. Mechanistically, mural cells physically contacted macrophages in the dura and transferred cytoplasmic components, including processing bodies (RNA granules shown to reprogram transcriptomes), which were critical to suppress antigen-dependent T helper (TH) cell activation and TH17 differentiation. Our study revealed a mechanism by which mural cell–macrophage interactions regulate the trafficking of CNS antigen-specific T cells to the dura.
Hamiltonian formulation of gravity as a spontaneously-broken gauge theory of the Lorentz group
Authors: Nikjoo Mehraveh , Zlosnik Tom
Published: January 2024

A number of approaches to gravitation have much in common with the gauge theories of the standard model of particle physics. In this paper, we develop the Hamiltonian formulation of a class of gravitational theories that may be regarded as spontaneously-broken gauge theories of the complexified Lorentz group

S
O
(
1
,
3

)

C

with the gravitational field described entirely by a gauge field valued in the Lie algebra of

S
O
(
1
,
3

)

C

and a ‘Higgs field’ valued in the group’s fundamental representation. The theories have one free parameter β which appears in a similar role to the inverse of the Barbero–Immirzi parameter of Einstein–Cartan theory. However, contrary to that parameter, it is shown that the number of degrees of freedom (DOFs) crucially depends on the value of β. For non-zero values of β, it is shown the theories possesses three complex DOFs, and for the specific values

β
=
±
i

an extension to general relativity is recovered in a symmetry-broken regime. For the value β = 0, the theory possesses no local DOFs. A non-zero value of β corresponds to the self-dual and anti-self-dual gauge fields appearing asymmetrically in the action, therefore in these models, the existence of gravitational DOFs is tied to chiral asymmetry in the gravitational sector.
Quasinormal mode spectrum of the AdS black hole with the Robin boundary condition
Authors: Kinoshita Shunichiro , Kozuka Tomohiro , Murata Keiju , Sugawara Keita
Published: January 2024

We study the quasinormal mode (QNM) spectrum of an asymptotically AdS black hole with the Robin boundary condition at infinity. We consider the Schwarzshild-AdS4with the flat event horizon as the background spacetime and study its scalar field perturbation. Denoting leading coefficients of slow- and fast-decay modes of the scalar field at infinity asφ1andφ2, respectively, we assume a linear relation between them asϕ2=cot(θ/2)ϕ1, whereθis a constant called the Robin parameter and periodic underθ∼θ+2π. In a certain range of the Robin parameter, there is an instability driven by the boundary condition. We also find the holonomy in the QNM spectrum under the parametric cycle of the boundary condition:θ=0→2π. After the one-cycle,nth overtone of the QNM moves to(n−1)th overtone. The fundamental tone of the QNM is swept out to the infinity in the complex plane.
Fabrication of high-aspect-ratio metallic microstructures by microelectroforming using silver-coated polydimethylsiloxane molds with controllable wettability
Authors: Zhou Bo , Xie Longfei , Wang Tingli , Su Bo , Meng Junhu
Published: January 2024

Microelectroforming is a specialized electroplating process to prepare functional metallic microstructures. However, the formability of microelectroforming is usually restricted by the limited mass transfer in high-aspect-ratio microcavities of molds. This paper presents a simple and reliable method utilizing silver (Ag)-coated polydimethylsiloxane (PDMS) molds with controllable wettability to enhance the formability of microelectroforming. The surfaces of these molds exhibited reversible water contact angles ranging from 4° to 151° realized through ultraviolet irradiation and heat treatment. The hydrophilicity of the PDMS molds facilitated liquid-phase mass transfer, contributing to the fabrication of complete and defect-free nickel microstructures with high aspect ratios. Subsequently, the hydrophobic PDMS molds reduced the interfacial adhesion between these molds and nickel microstructures, which was beneficial for perfect demolding. Nickel microstructures with an aspect ratio of 10 can be achieved by using the PDMS molds, which significantly enhance the formability of microelectroforming. This method provides a potential method to prepare high-aspect-ratio metallic microstructures.
Experimental study on femtosecond laser ablation of 4H–SiC substrate
Authors: Zhao Ziqiang , Zhao Lin , Peng Yun
Published: January 2024

Silicon carbide (SiC) is an ideal substrate for manufacturing high-power electronic devices and microwave devices and has broad application prospects. The surface treatment of SiC wafers plays a critical role and faces challenges in the semiconductor industry. Among the multiple treatment methods, the laser-based method has gradually attracted the attention of scholars. Therefore, this research uses a femtosecond laser to ablate 4H–SiC sliced wafers and analyzes the influence of key parameters, such as laser pulse energy, defocus amount, repetition frequency, and scanning intervals, on the laser ablation depth, width, and surface morphology. Scanning electron microscopy and laser coherence-focused microscopy were used to characterize the laser ablation surface. When the defocus amount was 6 mm, the microgroove profile formed by the laser was U-shaped. The scanning interval parameters had to be optimized to obtain the optimized surface roughness. The results show that the optimized surface roughness (Sa
) was 0.267 μm, and brittle fracture areas such as microcracks and pits on the original surface were removed. Effective removal facilitates further material surface processing, which provides valuable insights for similar researchers and benefits for the semiconductor industry.
First-principle investigation of structural, electronic, and phase stabilities in chalcopyrite semiconductors: insights from Meta-GGA functionals
Authors: Rani Dimple , Jana Subrata , K Niranjan Manish , Samal Prasanjit
Published: January 2024

We undertake a comprehensive first-principles investigation into the factors influencing the optoelectronic efficiencies of P
I
Q

I
I
I

R

2

V
I

chalcopyrite semiconductors. The structural attributes, electronic properties, and phase stabilities are explored using various meta-GGA exchange-correlation (XC) functionals within the density functional framework. In particular, we assess the relative performance of these XC functionals in obtaining estimates of various relevant parameters. The structural parameter u in chalcopyrite semiconductors is a noteworthy aspect, as it is intrinsically tied to the extent of orbital hybridization between distinct atoms and thereby strongly influences the electronic properties. In general, the application of widely used GGA-PBE XC functional to these chalcopyrites results in unreliable predictions of band gaps and ‘u’ parameter due to delocalization errors that in turn arise due to the inclusion of d and f core electrons. While hybrid functionals offer remarkable accuracy through state-of-the-art methods, their main drawback lies in their computational expense and resource demands. Our findings strongly suggest that in comparison to GGA-PBE, the meta-GGA XC functionals perform quite well and provide results that closely align with experimental values. In particular, the r
2SCAN and rMGGAC XC functionals are preferable and superior for investigating chalcopyrites and other solid-state systems. This preference is rooted in their excellent performance and substantially reduced computational costs compared to hybrid functionals.
Wavelet-based saturated absorption line detection for laser frequency locking
Authors: Li Guanghui , Zhou XinXiu , Duan Lihong , Wang Zhaoyu , Quan Wei
Published: January 2024

Owing to the presence of noise and the Doppler background, accurate saturated absorption (SA) peak automatic identification technology poses a significant challenge for laser frequency tuning and locking. To address this issue, a novel peak identification algorithm for the SA spectrum is proposed. First, a Gaussian filter based on a Gaussian continuous wavelet transform is proposed to mitigate the spectral high-frequency noise. Subsequently, a hybrid method combining a first-order Gaussian continuous wavelet transformation and adaptive threshold judgment was designed for multi-peak boundary segmentation. Finally, we obtained the target peak and its sweeping voltage based on an adaptive nonlinear fitting algorithm, which was almost unaffected by the peak asymmetry caused by the Doppler background.
Design of flexible sensor for wind pressure monitoring of stay cables
Authors: Wang Xiaoming , Guo Zhilong , Huang Yifeng , Xiong Longbo , Yao Daojin , Dong Wentao
Published: January 2024

Strong winds can make a bridge’s cable-stayed cables produce violent vibrations, leading to fatigue of the cable-stayed cables and damaging the cable-stayed bridge’s structure. Accurately and effectively obtaining data on the wind loads applied to the cable-stayed cables is important for assessing the cable-stayed cables’ health. The existing sensing elements for detection include diffusion silicon piezoresistive sensor, strain gauge, and other rigid sensors. However, most of them present such disadvantages as rigidity, difficult to fit the curved surface, high cost and low sensitivity. And it cannot be directly installed on the surface of the cable. In this paper, a conductive hydrogel flexible pressure sensor based on TA/CB@PDMS was developed, using carbon black (CB) as the main conductive medium, with good electrical conductivity, high sensitivity (0.65 kPa−1) and excellent tensile properties (210% tensile breakage). Meanwhile, a salt permeation method (Soak the sensor in LiBr solution) was used to effectively inhibit the sensor’s water from being evaporated and frozen. Its substrate incorporates tannic acid to increase the sensor’s adhesion so that it adheres well to the diagonal cable’s surface. In this paper, the wind speed variation around the diagonal cable and the force distribution on the surface with considering the fluid-structure coupling effect are analyzed by ANSYS WORKBECH finite element simulation. Wind tunnel experiments simulate the sensor’s force response when the inclined cable is subjected to different wind speeds, and the detection accuracy reaches 96.17%. The results show the sensor developed in this paper can realize accurate wind pressure detection of the inclined cable. This study provides a new method for wind pressure detection and health inspection of diagonal cables.
A fault diagnosis method for motor vibration signals incorporating Swin transformer with locally sensitive hash attention
Authors: Zeng Fei , Ren Xiaotong , Wu Qing
Published: January 2024

Identification of motor vibration signals is one of the important tasks in motor fault diagnosis and predictive maintenance, and wavelet time–frequency diagram is a commonly used signal analysis method to extract the frequency and time characteristics of signals. In this paper, a method based on local sensitive hashing (LSH)-Swin transformer network is proposed for identifying the wavelet time–frequency diagrams of motor vibration signals to analyze the fault types. The traditional Swin transformer model converges slowly due to the smoothing of the attention distribution when dealing with data with sparse features, while the method proposed in this paper reduces the smoothing of the computed attention and enables the network to learn the key features better by introducing locally-sensitive hash attention in the network model, dividing the sequences in the input attention into multiple hash buckets, calculating the attention weights of only some of the vectors with a high degree of hash similarity, and by sampling discrete samples with the use of the Gumbel Softmax. The experimental results show that the method proposed in this paper has better recognition accuracy and higher computational efficiency compared with the traditional network when processing wavelet time–frequency maps of motor vibration signals, and its validation accuracy reaches 99.7%, the number of parameters also has a decrease of about 13%, and the training network to reach converged epochs is also faster. The method in this paper can provide an effective solution for the analysis and processing of motor vibration signals, and has certain application value in practical engineering.
FastGNet: an efficient 6-DOF grasp detection method with multi-attention mechanisms and point transformer network
Authors: Ding Zichao , Wang Aimin , Gao Maosen , Li Jiazhe
Published: January 2024

A pivotal technology for autonomous robot grasping is efficient and accurate grasp pose detection, which enables robotic arms to grasp objects in cluttered environments without human intervention. However, most existing methods rely on PointNet or convolutional neural network as backbones for grasp pose prediction, which may lead to unnecessary computational overhead on invalid grasp points or background information. Consequently, performing efficient grasp pose detection for graspable points in complex scenes becomes a challenge. In this paper, we propose FastGNet, an end-to-end model that combines multiple attention mechanisms with the transformer architecture to generate 6-DOF grasp poses efficiently. Our approach involves a novel sparse point cloud voxelization technique, preserving the complete mapping between points and voxels while generating positional embeddings for the transformer network. By integrating unsupervised and supervised attention mechanisms into the grasp model, our method significantly improves the performance of focusing on graspable target points in complex scenes. The effectiveness of FastGNet is validated on the large-scale GraspNet-1Billion dataset. Our approach outperforms previous methods and achieves relatively fast inference times, highlighting its potential to advance autonomous robot grasping capabilities.
Stages assessment of state of health in a lifetime based on the capacity variance of lithium batteries
Authors: Meng Jiadong , Liu Lu , Zhao Zhigang , Su Chen
Published: January 2024

To avoid the overuse or underutilization of lithium battery in practical applications, the state of health (SOH) of lithium battery should be assessed in time to ensure safety and maximize utilization. A health indicator (HI) is proposed to show the SOH of lithium battery in this paper. Firstly, the degradation mechanism of lithium battery is described based on the working principle and the aging phenomenon of lithium-iron phosphate battery, and the existing problems in the current research on battery aging phenomenon are expounded. Secondly, to deal with the hidden dangers caused by the aging problem of the battery, the variation of capacity variance is selected to construct the HI of lithium battery. Finally, the performance degradation state of lithium battery is divided into four stages according to the changing trend of the constructed indicators in the whole lifetime, which are the formation stage of the first solid electrolyte interface (SEI) film stage, the normal working stage, the new SEI film stage and the internal resistance rise stage. The battery data set from MIT-Stanford-Toyota Research Center is utilized to verify the proposed method. The results show that the performance of lithium batteries will accelerate degradation with temperature rapidly rising in the new SEI film stage; the internal resistance will increase sharply in the internal resistance rise stage, which can easily lead to accidents such as thermal runaway. The proposed health state assessment method compares with other methods, and it is shown that the proposed method helps to ensure safety and maximize the utilization of lithium batteries.
Deformation health diagnosis of RCC dams considering construction interfaces based on monitoring data and numerical simulation
Authors: Chen Xudong , Li Liuyang , Liu Yajian , Zhao Yingda , Qin Xiangnan , Guo Jinjun , Xu Bo , Yang Guang
Published: January 2024

The health diagnosis procedure applied to determine the deformation of a roller compacted concrete (RCC) dam is different from that of a conventional concrete dam. Hence, in this study, a deformation health diagnosis model was established for an RCC dam considering the construction interfaces by combining the hydrostatic component simulated using ABAQUS (2016) with the temperature and aging components calculated using a statistical method. The combined method can help monitor the structural health of RCC dam and determine the physical meaning and statistical law of the deformation of RCC dams. During the simulation process, the geometric characteristics of the construction interfaces were modeled using the interface equivalent expansion method. The material properties were modeled using multi-output least-squares support vector regression optimized with the Jaya algorithm. A case study demonstrated that the established deformation health diagnosis model has good fitting and prediction ability. The model and methods proposed in this study provide a new idea for the behavior analysis and numerical simulation of mass composite structures similar to RCC dams.
Mechanical behavior of alpha quartz with void defects under tension: a molecular dynamics study using different interatomic potentials
Authors: Jia Yu , Zhang Huadian , Shukla Manoj K , Larson Steven , Nouranian Sasan , Rajendran A M , Jiang Shan
Published: January 2024

This study employs a series of molecular dynamics (MD) simulations, utilizing three commonly used interatomic potentials, i.e. van Beest, Kramer, and van Santen (BKS), Vashishta, and Tersoff to analyze the structural and mechanical characteristics within both void-free and single-void α-quartz configurations. Two distinct ensembles, NVT and NPT, were separately applied to investigate the tensile response. The validation of MD results included a comparative study of the three potentials as well as a comparison with experimental microstructural and tension studies. While BKS and Vashishta potentials accurately calculated the bond lengths, density and lattice parameters compared to the experimental values for void-free α-quartz, the results obtained with Tersoff potential exhibited relatively large deviations. The BKS potential offered an accurate description of the mechanical response of α-quartz by successfully predicting stress–strain curves. The Vashishta potential overpredicted Young’s modulus as compared to BKS. The Tersoff potential could capture the elastic deformation but was unable to predict the fracture behavior. The presence of a spherical void significantly reduced mechanical behavior of α-quartz, and the extent of this reduction was highly related to void size. When applying the BKS potential with an NVT ensemble, the ultimate tensile strengths decreased by 19% and 72% with void sizes of 2.5 and 15 Å, respectively. Equivalent stress analysis reveals that the BKS potential can effectively capture greater stress concentration around the void compared to other two potentials. Based on the comparison study, the BKS potential seems to be the most suitable one to describe α-quartz under tension in a realistic manner.
Center of mass of 2D and 3D objects and the golden ratio
Authors: Pathak Praveen , Kumar Aneesh , Kadolkar Charudatt
Published: January 2024

This study delves into the problem of finding the centre of mass for excised polygons in two and three dimensions, revealing intriguing connections and occurrences. We begin with rectangle and rhombus with sides in the ratio of the golden ratio, showcasing certain excised polygons with their centre of mass on the edge. Furthermore, we extend this analysis to 3D shapes like cuboids, pyramids, and cylinders, discovering three ways of excision, resulting in balanced objects on the edge. Exploring physics related to the centre of mass uncovers a fascinating mathematical coincidence between the golden ratio and the Fibonacci series. Additionally, we demonstrate and verify the center of mass location on the edges through 3D-printed objects.
Experimental simulation of quantum superchannels
Authors: Li Hang , Wang Kai , Wei Shijie , Yang Fan , Chen Xinyu , Sanders Barry C , Wang Dong-Sheng , Long Gui-Lu
Published: January 2024

Simulating quantum physical processes has been one of the major motivations for quantum information science. Quantum channels, which are completely positive and trace preserving processes, are the standard mathematical language to describe quantum evolution, while in recent years quantum superchannels have emerged as the substantial extension. Superchannels capture effects of quantum memory and non-Markovianality more precisely, and have found broad applications in universal models, algorithm, metrology, discrimination tasks, as examples. Here, we report an experimental simulation of qubit superchannels in a nuclear magnetic resonance (NMR) system with high accuracy, based on a recently developed quantum algorithm for superchannel simulation. Our algorithm applies to arbitrary target superchannels, and our experiment shows the high quality of NMR simulators for near-term usage. Our approach can also be adapted to other experimental systems and demonstrates prospects for more applications of superchannels.