bluuebunny/crossref_metadata_2025 huggingface dataset:
A high-sensitivity fiber Bragg grating sensor for displacement measurement in structural health monitoring
Authors: Yao Zhenjing , Li Mingyang , Li Guangmin , Xing Mengtao , Chen Ning
Published: September 2023

Displacement measurement is of great significance to monitor the crack variation and ensure the health of building structures. Aiming at the problems of low sensitivity and high temperature error of fiber Bragg grating (FBG) displacement sensors in displacement monitoring, this paper presents an adjustable cantilever beam displacement sensor with the FBGs as the sensing element. The sensor adds double FBGs on the relative surfaces of the equal-strength cantilever beam, which increases the bending deformation on the FBG of the beam surface to improve the sensitivity and realize the temperature compensation of the sensor. By adding an adjustable external rod structure between a flexible spring and a fixed foot stand, the sensor can regulate the range of initial crack width for different occasions. A theoretical analysis of the displacement sensor is performed, and the simulation analysis and optimization design for the structural parameters of the cantilever beam elastic sensitive element are implemented by adopting SolidWorks and ANSYS software. Finally, a displacement testing platform is constructed to test its performance. Experimental results show that this design has a high sensitivity coefficient of 39.47 pm/mm and a temperature coefficient of 1.04 pm/°C in the range of initial crack width from 0 to 110 mm or from 0 to 130 mm depending on different monitoring situations. Furthermore, good linearity, hysteresis delay, repeatability, and temperature compensation performance have also been demonstrated.
Numerical studies on applications of cavitation models in water hammer-induced cavitating flows in pipelines
Authors: Zhu Jianghui , Wu Guohong , Duan Xiangyu , Li Xiaoqin , Tang Xuelin
Published: September 2023

Hydraulic transients caused by a fast-closing needle valve and accompanying water hammer-induced cavitation-vortex flow are numerically investigated using the shear stress transport (SST) k–ω model with a pressure–density equation considering the weak compressibility of water and the new cavitation models based on the Rayleigh–Plesset equation that takes into account the surface tension and kinematic viscosity effect on the bubble radius change rate, respectively. The predicted pressure evolutions exhibit reasonable agreement with the experimental data, and the interfacial surface tension-based model is the most accurate in predicting transient pressure evolutions, followed by the kinematic viscosity-based model and the Singhal cavitation model, based on three proposed error indices with minimum of 0.0515, 0.1337, and 0.0035. The wave speed in the upper part of the cavitation trailing edge is higher than that in the lower part, resulting in the evolution of inclination angle of the trailing edge. According to the convective transport mechanism of vorticity, the change rate of vorticity in non-cavitation regions is mainly dominated by the stretching–twisting term and the turbulent fluctuation–diffusion term. In cavitation regions, the dilatation–shrink term makes significant contributions to the change rate of vorticity, and the baroclinic-torque term mainly acts near the edge of the cavitation region.
Morphing optimization of flow and heat transfer in concentric tube heat exchangers
Authors: Ali Samer , Dbouk Talib , Khaled Mahmoud , Faraj Jalal , Drikakis Dimitris
Published: September 2023

Concentric tube heat exchangers are vital in various industrial applications, including chemical, process, energy, mechanical, and aeronautical engineering. Advancements in heat transfer efficiency present a significant challenge in contemporary research and development. This study concerns optimizing flow and heat transfer in concentric tube heat exchangers by morphing the tube's walls. The adjoint shape optimization approach is implemented in a fully turbulent flow regime. The effect of inner tube deformation on flow physics and heat transfer is examined. The results show that morphing can lead to a 54% increase in the heat transfer rate and a 47% improvement in the overall heat transfer coefficient compared to straight concentric tube designs. Moreover, the thermal-hydraulic performance factor is calculated to account for the relative increase in heat transfer when the optimal and initial designs are operated under the same pumping power. A thermal-hydraulic performance factor of 1.2 is obtained for the new design, showing that the heat transfer enhancement caused by morphing the tube's walls outweighs the increase in pumping power. The physics of a radial flow, resulting from an adverse pressure gradient in an annular region caused by the successive inner tube deformation, significantly augments heat transfer. This study shows morphing can lead to higher thermal efficiencies, and numerical optimization can assist in achieving this goal.
Laminar flow over a rectangular cylinder experiencing torsional flutter: Dynamic response, forces and coherence modes
Authors: Zhu Qingchi , Zhou Lei , Wen Jiahao , Liu Tingting , Zhang Jize , Tang Hui , Zhang Hongfu
Published: September 2023

This study investigates the flutter response of a rectangular cylinder model with an aspect ratio of 5 at the Reynolds number Re = 100 via direct numerical simulation. The effects of two key parameters, i.e., the moment of inertia and reduced flow velocity, on the aerodynamic performance and dynamic responses of the cylinder in the state of torsional flutter are investigated. To reveal the flutter mechanism, the high-order dynamic mode decomposition (HODMD) analysis is conducted to decompose the flow field. The results show that both an increase in the moment of inertia and a higher reduced flow velocity lead to a larger torsional amplitude and a corresponding decrease in torque. At the same time, the primary frequency decreases and the size of the shedding vortex gradually enlarges. The vortices shed from the leading edge and the trailing edge of the model form a 2P wake pattern. The leading-edge vortex is significantly larger than the trailing-edge vortex in terms of strength and size. The leading edge plays a dominant role and only contributes to the odd-order HODMD modes while the even-order modes are deemed inconsequential. As the moment of inertia increases, the total energy of the higher-order modes increases, which has the same results as the power spectral density of torque, reflecting increased nonlinearity and complexity of the system. Similarly, increasing the reduced flow velocity at the same moment of inertia has similar excitation effects.
Exploring conformations of comb-like polymers with varying grafting density in dilute solutions
Authors: Salinas-Soto Carlos A. , Choe Yeojin , Hur Su-Mi , Ramírez-Hernández Abelardo
Published: September 2023

Comb-like polymers have shown potential as advanced materials for a diverse palette of applications due to the tunability of their polymer architecture. To date, however, it still remains a challenge to understand how the conformational properties of these polymers arise from the interplay of their architectural parameters. In this work, extensive simulations were performed using dissipative particle dynamics to investigate the effect of grafting density, backbone length, and sidechain length on the conformations of comb-like polymers immersed in a good solvent. To quantify the effect of these architectural parameters on polymer conformations, we computed the asphericity, radius of gyration, and backbone and sidechain end-to-end distances. Bond–bond correlation functions and effective Kuhn lengths were computed to quantify the topological stiffness induced by sidechain–sidechain interactions. Simulation results reveal that the effective Kuhn length increases as grafting density and sidechain length increase, in agreement with previous experimental and theoretical studies. This increase in stiffness results in comb-like polymers adopting extended conformations as grafting density and sidechain length increase. Simulation results regarding the radius of gyration of comb-like polymers as a function of grafting density are compared with scaling theory predictions based on a free energy proposed by Morozova and Lodge [ACS Macro Lett. 6, 1274–1279 (2017)] and scaling arguments by Tang et al. [Macromolecules 55, 8668–8675 (2022)].
Mesoscopic two-point collective dynamics of glass-forming liquids
Authors: Shen Zhiqiang , Carrillo Jan-Michael Y. , Sumpter Bobby G. , Wang Yangyang
Published: September 2023

The collective density–density and hydrostatic pressure–pressure correlations of glass-forming liquids are spatiotemporally mapped out using molecular dynamics simulations. It is shown that the sharp rise of structural relaxation time below the Arrhenius temperature coincides with the emergence of slow, nonhydrodynamic collective dynamics on mesoscopic scales. The observed long-range, nonhydrodynamic mode is independent of wave numbers and closely coupled to the local structural dynamics. Below the Arrhenius temperature, it dominates the slow collective dynamics on length scales immediately beyond the first structural peak in contrast to the well-known behavior at high temperatures. These results highlight a key connection between the qualitative change in mesoscopic two-point collective dynamics and the dynamic crossover phenomenon.
High temperature non-equilibrium flow characteristics of impinging shock/flat-plate turbulent boundary layer interaction at Mach 8.42
Authors: Dai Chunliang , Sun Bo , Zhao Dan , Zhou Shengbing , Zhou Changsheng , Man Yanjin
Published: September 2023

There are fewer reports on the impinging shock/boundary layer interaction in the high Mach number and high-temperature flow than that in the supersonic flow. High-temperature flow characteristics of the impinging shock/flat-plate turbulent boundary layer interaction (IS/FTBLI) at Mach 8.42 are numerically investigated by solving two-dimensional Reynolds averaged Navier–Stokes equations coupling with the thermal–chemical non-equilibrium model. An impinging shock is formed by the wedge with a 10° deflection angle. The inviscid flow parameters ahead of the cowl of a Mach 12 inlet are selected as the free-stream condition of this study. The primary emphasis of this study lies in understanding the thermal–chemical non-equilibrium effects in the IS/FTBLI. Moreover, the chemical non-equilibrium effects similar to previous reports from others are utilized for the comparative analysis. Our findings reveal that the vibrational or thermal non-equilibrium effects exhibit maximum prominence subsequent to the intersection of the impinging shock with separation shock, as well as in the convergence area of compression waves during the flow reattachment. On the other hand, the chemical non-equilibrium effects predominantly result from oxygen dissociation and atomic nitrogen production within the boundary layer; the chemical reactions are most intense within the separation zone. By comparing with a thermally perfect gas, a reduction in the flow separation is observed in the chemical non-equilibrium effects, but the flow separation is enhanced in the thermal–chemical non-equilibrium effects. The insights gained from our research are expected to contribute to the development of flow control technology in hypersonic IS/FTBLI scenarios and aid in configuring wave structures in the inner compression section of high Mach number scramjet inlets.
Electron spin polarization in supramolecular polymers with complex pathways
Authors: Hong Kyeong-Im , Kumar Abhinandan , Garcia Ana M. , Majumder Subrata , Ruiz-Carretero Amparo
Published: September 2023

Mastering the manipulation of the electron spin plays a crucial role in comprehending the behavior of organic materials in several applications, such as asymmetric catalysis, chiroptical switches, and electronic devices. A promising avenue for achieving such precise control lies in the Chiral Induced Spin Selectivity (CISS) effect, where electrons with a favored spin exhibit preferential transport through chiral assemblies of specific handedness. Chiral supramolecular polymers emerge as excellent candidates for exploring the CISS effect due to their ability to modulate their helical structure through noncovalent interactions. In this context, systems capable of responding to external stimuli are particularly intriguing, sometimes even displaying chirality inversion. This study unveils spin selectivity in chiral supramolecular polymers, derived from single enantiomers, through scanning tunneling microscopy conducted in scanning tunneling spectroscopy mode. Following two distinct sample preparation protocols for each enantiomer, we generate supramolecular polymers with opposite handedness and specific spin transport characteristics. Our primary focus centers on chiral π-conjugated building blocks, with the aim of advancing novel systems that can inspire the organic spintronics community from a supramolecular chemistry level.
Experimental and fluid flow simulation studies of laser-electrochemical hybrid manufacturing of micro–nano symbiotic superamphiphobic surfaces
Authors: Liu Yang , Liu Xinyu , Zhang Zhaoyang , Lu Jinzhong , Wang Yufeng , Xu Kun , Zhu Hao , Wang Bo , Lin Liqu , Xue Wei
Published: September 2023

Micro–nano symbiotic superamphiphobic surfaces can prevent liquids from adhering to metal surfaces and, as a result, improve their corrosion resistance, self-cleaning performance, pollution resistance, and ice resistance. However, the fabrication of stable and controllable micro–nano symbiotic superamphiphobic structures on metal surfaces commonly used in industry remains a significant challenge. In this study, a laser-electrochemical hybrid subtractive–additive manufacturing method was proposed and developed for preparing copper superamphiphobic surfaces. Both experimental and fluid simulation studies were carried out. Utilizing this novel hybrid method, the controllable preparation of superamphiphobic micro–nano symbiotic structures was realized. The experimental results showed that the prepared surfaces had excellent superamphiphobic properties following subsequent modification with low surface energy substances. The contact angles of water droplets and oil droplets on the surface following electrodeposition treatment reached values of 161 ± 4° and 151 ± 4°, respectively, which showed that the prepared surface possessed perfect superamphiphobicity. Both the fabrication method and the test results provided useful insights for the preparation of stable and controllable superamphiphobic structures on metal surfaces in the future.
Analysis of near field mutual coupling in wideband magnetoelectric antennas array
Authors: Dong Biao , Yan Zhongming , Zhang Yong , Han Tianhao , Zhou Hongcheng , Wang Yu
Published: September 2023

The operating bandwidth of miniaturized magnetoelectric (ME) antenna is generally narrow due to the acoustic wave driven magneto-electromechanical resonance effect, parallel connection of multiple ME antennas with different resonant frequencies is an effective way to broaden the operating bandwidth of the antenna. This paper presents an ME antenna array consisting of three units, which are constructed of a sandwich stack of Metglas/Pb(Mg1/3Nb2/3)O3–PbTiO3/Metglas. The −3 dB operating bandwidth of 152.4–172.8 kHz is achieved, and the relative bandwidth is 12.5%. Experimental results indicated that the bias magnetic field and coupling effect between the ME antenna units significantly influence the performance of ME antenna array. A modified Butterworth–Van Dyke (MBVD) equivalent circuit model is used and improved to analyze the influence of sound waves, electric fields, magnetic fields, parasitic capacitance, and bias magnetic field on the ME antenna array. The simulation results of the MBVD equivalent circuit model are agreed well with the experimental results. The improved MBVD model is beneficial for the design of acoustic wave driven antenna array.
A spectrum adaptive kernel polynomial method
Authors: Chen Tyler
Published: September 2023

The kernel polynomial method (KPM) is a powerful numerical method for approximating spectral densities. Typical implementations of the KPM require an a prior estimate for an interval containing the support of the target spectral density, and while such estimates can be obtained by classical techniques, this incurs addition computational costs. We propose a spectrum adaptive KPM based on the Lanczos algorithm without reorthogonalization, which allows the selection of KPM parameters to be deferred to after the expensive computation is finished. Theoretical results from numerical analysis are given to justify the suitability of the Lanczos algorithm for our approach, even in finite precision arithmetic. While conceptually simple, the paradigm of decoupling computation from approximation has a number of practical and pedagogical benefits, which we highlight with numerical examples.
Assessment of cavitation erosion risk indicated by pressure impact exceeding material strength threshold
Authors: Qiu Ning , Zhu Han , Xu Pei , Che Bangxiang , Wu Jie , Zhou Wenjie , Wang Chuan
Published: September 2023

Cavitation erosion can seriously affect the performance of hydraulic machinery. To assess its risk, the cavitation erosion that covered a NACA0015 hydrofoil was investigated using experiment and simulation. In particular, the material strength threshold was considered in the experiment, and soft specimens were employed instead of common painting surfaces. High-speed cameras were utilized to capture cavity morphology, while pressure sensors simultaneously measured the impact intensity of cavitation collapse. Additionally, an erosion assessment method based on pressure impact was used in the numerical simulation. The results indicate that the cavitation erosion risk can be indicated by the intensity of pressure impact, which is caused by the collapse of cavity. The high erosion risk appears near 60% of chord length where shedding cloud collapses. Due to the influence of middle-entrant jet and side-entrant jets, the erosion risks are different at various span-wise locations. Additionally, the response differs for different materials exposed to cavitation. When the material strength threshold is low, the chord-wise difference of cavitation erosion is not significant, because the slight impact can also generate erosion pits. When the threshold is high, the chord-wise difference of erosion becomes larger, and erosion pits are more centralized.
The interplay of vibronic and spin–orbit coupling in the fluorescence quenching in trans-dithionated PDI
Authors: Dakua Kishan Kumar , Rajak Karunamoy , Mishra Sabyashachi
Published: September 2023

Organic chromophores such as the thionated derivatives of perylene diimides (PDIs) show prolonged triplet-excited state lifetimes in contrast to their pristine parent PDI molecule, which shows near unity fluorescence quantum yield. The excited state dynamics in the trans-dithionated PDI (S2-PDI) are studied here. Unlike PDI, the photo absorbing ππ* state of S2-PDI is in close proximity to quasi-degenerate nπ* states. The latter exhibits an interesting vibronic problem leading to the breaking of orbital symmetry mediated through non-totally symmetric vibrations. The time-dependent quantum dynamics are studied with a diabatic model Hamiltonian involving three singlet and three triplet states coupled via 22 vibrational modes. A combined effect of multiple internal-conversion and inter-system crossing (ISC) pathways leads to population transfer from the 1ππ* state to the 3ππ* state via the nπ* states, with an overall ISC rate of 0.70 ps that compares well with the experimental value. The calculated absorption spectra for PDI and S2-PDI reproduce the essential vibronic features in the observed experimental spectra. The dominant vibronic progressions are found to have significant contributions from the vinyl stretching modes of the PDI core.
Analytical model of space charge limited current for a cylindrical porous trap-limited dielectric
Authors: Kanwal Samra , Kee Chun Yun , Ang L. K.
Published: September 2023

In this study, analytical models for space charge limited current (SCLC) transport in a porous (or disordered) trap-limited dielectric cylindrical configuration are developed. The method used in this paper is first verified by reproducing the well-known analytical results for planar cases developed decades ago based on the traditional approach. By considering the porous solid as a fractional object characterized by a parameter α≤1, we formulate its fractional capacitance and determine the SCLC transport by using the transit time approach. At α=1, it will recover the well-known Mott–Gurney law and Mark–Helfrich law for trap-free and trap-limited cases, respectively. For cylindrical geometry, our findings show an analytical form that is not available from the traditional methods. We anticipate that the proposed analytical model will serve as a useful tool for characterizing the current–voltage measurements in SCLC transport in dielectric breakdown and organic electronics, where spatial porosity of the materials is inevitable. The introduced fractional parameter α extracted from such characterization can facilitate the quantitative determination of the relationship between spatial porosity and charge mobility.
Effects of spatial–temporal conditions and fishing-vessel capacity on the capture of swimming crabs by using different fishing gear around the waters of Taiwan
Authors: Naimullah Muhamad , Lan Kuo-Wei , Liao Cheng-Hsin , Yang Yu-Jhen , Chen Chao-Ching , Liew Hon Jung , Ikhwanuddin Mhd
Published: September 2023

Context Swimming crab is a vital fishery resource and a valuable source of income in the southern East China Sea, but it lacks management strategies, especially when using different fishing gear. Aims This study aimed to determine the effects of spatial–temporal conditions and vessel capacity on swimming crabs by using different fishing-gear types in the Taiwan Strait (TS). Methods We used generalised linear mixed models (GLMMs) to investigate data from Taiwanese vessels (2011–2019) on how spatial–temporal conditions and vessel capacity affected the catch of swimming crabs when using trawls, gill-nets and traps. Key results The results showed that the traps (>80.0%) caught more swimming crabs in the TS than did the gill-nets (6.6%) and trawls (8.0%). Additionally, the GLMM analysis showed that Charybdis feriatus, Portunus pelagicus and Portunus sanguinolentus catches by traps and trawls were significantly affected by different fishing locations, climate events, work hours and vessel sizes. However, for gill-nets, spatial–temporal conditions and vessel capacity did not affect the catch of C. feriatus. Conclusions Monitoring fishing efforts and environmental factors is vital to understanding their impacts on marine ecosystems. Implications These findings enable future sustainable crab fishing through harvesting strategy planning, ecosystem management and spatial–temporal governance.
Quantifying the flammability of living plants at the branch scale: which metrics to use?
Authors: Cawson J. G. , Burton J. E. , Pickering B. J. , Demetriou V. , Filkov A. I.
Published: September 2023

Background Plant flammability is an important factor in fire behaviour and post-fire ecological responses. There is consensus about the broad attributes (or axes) of flammability but little consistency in their measurement. Aims We sought to provide a pathway towards greater consistency in flammability research by identifying a subset of preferred flammability metrics for living plants. Methods Flammability was measured at the branch scale using a range of metrics for 140 plant specimens in an apparatus that simulates an approaching fire front. Key results We identified a subset of preferred metrics, which quantify the axes of flammability for living plants, including time to ignition (ignitability), peak heat release rate (combustibility), flaming duration (sustainability) and consumption (consumability). Flaming duration was strongly correlated with heat release rate, so could be a proxy for combustibility. Flammability was higher for species with greater surface area and biomass per branch. Conclusions We identified a subset of preferred metrics for quantifying the flammability of living plants. These metrics quantify the key axes of flammability and are measurable using different experimental apparatus and across multiple scales, making them suitable for widespread use. Implications The inclusion of these flammability metrics in future studies has the potential to enhance consistency and comparability between studies.
Comparison of oral and written argumentation by Ultra-OrthodoxJewish students
Authors: Tsemach Ehud
Published: September 2023

This study examines the relations between oral and written argumentation in two contexts: written assignments and structured interviews among Ultra-Orthodox (Haredi) Jewish students in Israeli higher education. The segregated education system for Haredi students focuses on dyadic oral discussions about religious texts. When Haredi men start their way in academia, they move from an oral to a written culture. To understand this complex process, I compared forty argumentative essays and structured interviews of Ultra-Orthodox students. I identified which argumentative patterns recurred or differed across the two contexts. The comparison elicited complex findings: whereas dialectic patterns of weighing supporting and opposing arguments and counterarguments were prominent in both contexts, sweeping generalizations and firm arguments were found mainly in the essays. The similarity of the argumentative patterns in writing and in the interviews may be explained by the stability of argument schemata across different contexts. The findings expand on previous theoretical and empirical findings and demonstrate how the dialectic process of examining different perspectives leads to complex positions. Finally, I present educational implications for teaching argumentation, such as careful activity design and choosing discussion topics that elicit weighing and sophisticated arguments.
“Fingers which mean นิ้ว นิ้วแบบนิ้วมือ”
Authors: Tachaiyaphum Nutthida , Gurney Laura , Daly Nicola
Published: September 2023

This article explores pre-service teachers’ L1 use in Thai Content and Language Integrated Learning (CLIL)
secondary classrooms through the translanguaging frame, which emphasises the use of the whole linguistic and semiotic repertoire
in the classroom to make meaning and construct new knowledge. Teachers may choose to make deliberate use of learners’ linguistic
repertoires in classroom activities to enhance understanding and develop learners’ communicative abilities beyond narrowly defined
language codes. We investigate how pre-service English as a Foreign Language (EFL) teachers employed a translanguaging approach to
model tasks and provide definitions of key terms. We explore the teachers’ beliefs concerning L1 use, drawing attention to the
apparent tension between teachers’ practices and beliefs. The findings indicate that the teachers utilised translanguaging in
different modes, including modeling tasks and translating L2 terms, to address students’ comprehension problems. However, the
teachers expressed mixed beliefs concerning how and when L1 should be used.
Hemifacial myohyperplasia is due to somatic muscular PIK3CA gain-of-function mutations and responds to pharmacological inhibition
Authors: Bayard Charles , Segna Eleonora , Taverne Maxime , Fraissenon Antoine , Hennocq Quentin , Periou Baptiste , Zerbib Lola , Ladraa Sophia , Chapelle Célia , Hoguin Clément , Kaltenbach Sophie , Villarese Patrick , Asnafi Vahid , Broissand Christine , Nemazanyy Ivan , Autret Gwennhael , Goudin Nicolas , Legendre Christophe , Authier François-Jérôme , Viel Thomas , Tavitian Bertrand , Gitiaux Cyril , Fraitag Sylvie , Duong Jean-Paul , Delcros Clarisse , Sergent Bernard , Picard Arnaud , Dussiot Michael , Guibaud Laurent , Khonsari Roman , Canaud Guillaume
Published: September 2023

Hemifacial myohyperplasia (HFMH) is a rare cause of facial asymmetry exclusively involving facial muscles. The underlying cause and the mechanism of disease progression are unknown. Here, we identified a somatic gain-of-function mutation of PIK3CA in five pediatric patients with HFMH. To understand the physiopathology of muscle hypertrophy in this context, we created a mouse model carrying specifically a PIK3CA mutation in skeletal muscles. PIK3CA gain-of-function mutation led to striated muscle cell hypertrophy, mitochondria dysfunction, and hypoglycemia with low circulating insulin levels. Alpelisib treatment, an approved PIK3CA inhibitor, was able to prevent and reduce muscle hypertrophy in the mouse model with correction of endocrine anomalies. Based on these findings, we treated the five HFMH patients. All patients demonstrated clinical, esthetical, and radiological improvement with proof of target engagement. In conclusion, we show that HFMH is due to somatic alteration of PIK3CA and is accessible to pharmacological intervention.
Eccentric catastrophes & what to do with them
Authors: Loutrel Nicholas
Published: September 2023

Analytic modeling of gravitational waves (GWs) from inspiraling eccentric binaries poses an interesting mathematical challenge. When constructing analytic waveforms in the frequency domain, one has to contend with the fact that the phase of the Fourier integral in non-monotonic, resulting in a breakdown of the standard stationary phase approximation (SPA). In this work, we study this breakdown within the context of catastrophe theory. We find that the SPA holds in the context of eccentric Keplerian orbits when the Fourier frequency satisfies

f

m
i
n

<
f
<

f

m
a
x

, where

f

m
i
n

/

m
a
x

are integer multiples of the apocenter/pericenter frequencies, respectively. For values outside of this interval, the phase undergoes a fold catastrophe, giving rise to an Airy function approximation of the Fourier integral. Using these two different approximations, we generate a matched asymptotic expansion that approximates generic Fourier integrals of Keplerian motion for bound orbits across all frequency values. This asymptotic expansion is purely analytic and closed-form. We discuss several applications of this investigation and the resulting approximation, specifically: (1) the development and improvement of effective fly-by waveforms for binary black holes, (2) the transition from burst emission in the high eccentricity limit to wave-like emission in the quasi-circular limit, which results in an analogy between eccentric GW bursts and Bose–Einstein condensates, and (3) the calculation of f-mode amplitudes in eccentric binary neutron stars and black hole-neutron star binaries in terms of complex Hansen coefficients. The techniques and approximations developed herein are generic, and will be useful for future studies of GWs from eccentric binaries within the context of post-Newtonian theory.
Charged spherically symmetric black holes in scalar-tensor Gauss–Bonnet gravity
Authors: Capozziello Salvatore , Nashed Gamal G L
Published: September 2023

We derive a novel class of four-dimensional black hole (BH) solutions in Gauss–Bonnet (GB) gravity coupled with a scalar field in presence of Maxwell electrodynamics. In order to derive such solutions, we assume the ansatz

g

t
t

≠

g

r
r

−
1

for metric potentials. Due to the choice of the ansatz of the metric, the Reissner Nordström gauge potential cannot be recovered because of the presence of higher-order terms

which are not allowed to be vanishing. Moreover, the scalar field is not allowed to vanish. If it vanishes, a function of the solution results undefined. Furthermore, it is possible to show that the electric field is of higher-order in the monopole expansion: this fact explicitly comes from the contribution of the scalar field. Therefore, we can conclude that the GB scalar field acts as non-linear electrodynamics creating monopoles, quadrupoles, etc in the metric potentials. We compute the invariants associated with the BHs and show that, when compared to Schwarzschild or Reissner–Nordström space-times, they have a soft singularity. Also, it is possible to demonstrate that these BHs give rise to three horizons in AdS space-time and two horizons in dS space-time. Finally, thermodynamic quantities can be derived and we show that the solution can be stable or unstable depending on a critical value of the temperature.
Pulsed photoemission induced plasma breakdown
Authors: Iqbal Asif , Bentz Brian Z , Zhou Yang , Youngman Kevin , Zhang Peng
Published: September 2023

This article characterises the effects of cathode photoemission leading to electrical discharges in an argon gas. We perform breakdown experiments under pulsed laser illumination of a flat cathode and observe Townsend to glow discharge transitions. The breakdown process is recorded by high-speed imaging, and time-dependent voltage and current across the electrode gap are measured for different reduced electric fields and laser intensities. We employ a 0D transient discharge model to interpret the experimental measurements. The fitted values of transferred photoelectron charge are compared with calculations from a quantum model of photoemission. The breakdown voltage is found to be lower with photoemission than without. When the applied voltage is insufficient for ion-induced secondary electron emission to sustain the plasma, laser driven photoemission can still create a breakdown where a sheath (i.e. a region near the electrode surfaces consisting of positive ions and neutrals) is formed. This photoemission induced plasma persists and decays on a much longer time scale (

∼
10
s

μ

s) than the laser pulse length (

30

ps). The effects of different applied voltages and laser energies on the breakdown voltage and current waveforms are investigated. The discharge model can accurately predict the measured breakdown voltage curves, despite the existence of discrepancy in quantitatively describing the transient discharge current and voltage waveforms.
Pseudogap in BaPb
x
Bi1‒x
O3 (x = 0.7, 0.75 and 1.0)
Authors: Bharath M , Brar Jaskirat , Pant Himanshu , Ali Asif , Bansal Sakshi , Shankar Singh Ravi , Bindu R
Published: September 2023

In this work, we have investigated the crystal and electronic structure of the orthorhombic phase of BaPb
x
Bi

1
−
x

O3 (BPBO) for x = 0.7 (BPBO70), 0.75 (BPBO75) and 1.0 (BPO), using temperature dependent x-ray diffraction measurements, photoemission spectroscopy, and electronic structure calculations. Our results show the importance of particle size and strain in governing superconductivity. Interestingly, the temperature evolution of the structural parameters in the case of BPBO70 is similar to that of BPBO75 but the magnitude of the change is diminished. The BPBO75 and BPO compounds exhibit metallic nature, which is corroborated by the core level studies. The electronic structure calculations in conjunction with the core level studies suggest that oxygen vacancies play an important role for metallicity observed in the end compound. The exponent to the spectral line shape close to the Fermi level suggests the origin of pseudogap to be due to other contributions in addition to disorder in the case of BPBO70 and BPO. The core level studies also show that as one goes from x = 0.70 to 1.0, there occurs chemical potential shift towards the valence band suggesting hole doping. Our results open the venue to further study these compounds as a function of particle size, nature of carriers for its transport behaviour, electronic structure below TC
, composition at the grain boundaries and microscopic origin of pseudogap in the non-superconducting phase. We believe that our results call for a revision of the temperature-doping phase diagram of BPBO to include the pseudogap phase.
Strain engineering on electronic structure, effective mass and charge carrier mobility in monolayer YBr3
Authors: Sun Huaizheng , Wang Linxia , Li Zhixiang , Yan Xiaobing , Zhang Xin , Guo Jianxin , Liu Pan
Published: September 2023

In recent years, two-dimensional materials have significant prospects for applications in nanoelectronic devices due to their unique physical properties. In this paper, the strain effect on the electronic structure, effective mass, and charge carrier mobility of monolayer yttrium bromide (YBr3) is systematically investigated using first-principles calculation based on density functional theory. It is found that the monolayer YBr3 undergoes energy band gap reduction under the increasing compressive strain. The effective mass and charge carrier mobility can be effectively tuned by the applied compressive strain. Under the uniaxial compressive strain along the zigzag direction, the hole effective mass in the zigzag direction (m
ao1_h) can decrease from 1.64 m
0 to 0.45 m
0. In addition, when the uniaxial compressive strain is applied, the electron and hole mobility can up to ∼103 cm2 V−1 s−1. The present investigations emphasize that monolayer YBr3 is expected to be a candidate material for the preparation of new high-performance nanoelectronic devices by strain engineering.
An intelligent feature recognition method of natural gas pipelines based on shapelet and blending fusion model
Authors: Ma Tingxia , Hu Cheng , Wang Lin , Ma Linjie , Mao Zhihao , Xuan Heng
Published: September 2023

Despite the availability of pipeline bending strain detection technologies based on inertial measurement unit, there is a lack of intelligent and efficient methods for accurately identifying pipeline features by bending strain. Therefore, this paper proposes a novel method for identifying features in natural gas pipelines based on shapelet and blending fusion model. Specifically, the shape features of the bending strain data are extracted and transformed by shapelet. Then a blending fusion model with SVM, Decision Tree and Gradient Boosting as base learners and Random Forest as meta-learner is constructed. Finally, the extracted features are fed into the blending fusion model for pipeline feature recognition. The model is trained with bending strain data obtained from a real natural gas pipeline, the results indicate that the recognition accuracy of the proposed method is 97.17%. Compared with other models, the superiority of the proposed model is verified, and it is proved that the proposed method has better accuracy than the existing models (over 1.3%). Overall, the method proposed in this paper can be effectively combined with the in-line inspection system to provide a reference for pipeline companies to carry out pipeline integrity management.
Wide frequency range optical chopper system: an affordable solution using 3D printing and Arduino Uno
Authors: Rana Ankush , Bhatnagar Shivansh , Garg Sagar , Garg Amit
Published: September 2023

We have developed a wide frequency range affordable optical chopper system from 10–550 Hz. It is a self-contained prototype built using 3D design and printing and Arduino UNO. The system consists of six chopper wheels that are 3D designed using open-source software, Blender and printed on FlashForge 3D printer using polylactic acid. Two Arduino Uno’s have been deployed in the present system- One for controlling the rotation speed of the optical choppers and another for frequency measurement of the modulated output. The adoption of open-source approach makes it possible for any undergraduate (UG) or researcher to emulate the present system with possible modifications as per their need for use in their laboratories. It has made optical chopper system which is a widely used instrument, affordable for the UG/research labs costing below USD 50 whereas the cost of the commercially available systems is in the range of USD 800–1000 and that too with a matching performance and adaptability.
Particle simulations for inquiry-based teaching of polymer shape and entropic elasticity using computational thinking
Authors: Kraska Thomas
Published: September 2023

An inquiry-based approach is proposed that allows students to develop and understand computer codes for simulations at the particle level. Computational thinking is employed as a low-threshold approach for students without programming experience. The resulting computer code cores are concise and traceable. Here, the topic of the simulations concerns polymer molecules. A special property of polymers, coiling, and the related entropic elasticity is suitable for the setup of a simulation in class. Students at the upper secondary level were introduced into the topic by an activity. This was a stochastic game serving as a basis to for the development of the corresponding algorithm. Once students are involved in the development of the code, they can meaningfully investigate the model by running the program, changing its parameters, or altering the code. With these simulations, students can prove wrong the early belief that polymer molecules exhibit a stretched chain structure. Furthermore, the confinement of the system leads to a decrease in entropy, which in turn results in a force acting on the walls that can be elaborated comprehensively by students through such simulations.
Verification experiment of the coefficient of static and kinetic friction utilizing a mobile application
Authors: Bug-os Mary Allein Antoenette C , Marte Sherwin J , Pili Unofre B
Published: September 2023

This study is conducted to determine the coefficient of static and kinetic friction. The average angle of inclination measured for the coefficient of static friction is used as the angle of inclination of the plane when measuring the acceleration of the cardboard on wood as a variable in determining the coefficient of kinetic friction. Importantly, it verifies that the coefficient of static friction is greater than the coefficient of kinetic friction by utilizing the Phyphox application.
Example activity: how to determine the center of mass of a body if the center of mass is outside the body?
Authors: Şahin Esin
Published: September 2023

The centre of mass (CM) is a key concept that facilitates the understanding of various physics topics and the solution of problems. This study’s aim is to present an activity for students to experimentally determine the location of the CM of bodies with a CM outside the body. Thus, an example activity will be presented that will allow students to understand the situation where the CM is outside the body, to find the CM of bodies, and to generate new examples with a CM outside the body themselves. For at-rest bodies, the common experimental technique for finding the CM of the body consists of drawing two vertical gravity lines through the body, and the CM is at the intersection of these lines. In this research, this technique is adapted to cases where the CM is outside the body.
Improvement of critical current properties and irreversibility lines by metal substitution in Ca-free Hg-based double-layered cuprates
Authors: Ninomiya Hiroki , Kawashima Kenji , Ishida Shigeyuki , Ogino Hiraku , Fujihisa Hiroshi , Gotoh Yoshito , Yoshida Yoshiyuki , Iyo Akira , Eisaki Hiroshi
Published: September 2023

Ca-free Hg-based double-layered cuprates with Sr ions separating the two CuO2 planes, Hg(Sr Ba)2SrCu2O
y
and its metal-substituted analogue of (Hg, M)(Sr Ba)2SrCu2O
y
(

M
=
Mo

, Re, and Pb), were successfully synthesized under high pressure. These novel materials exhibit bulk superconductivity at a critical temperature above 100 K. The superconducting properties, including critical current density

(

J
c

)

and irreversibility field

(

B
irr

)

, were investigated through magnetic hysteresis loop measurements. Our results revealed that the M substitution with

M
=
Mo

and Re improves the J
c and B
irr properties, which is likely associated with a decrease in the thickness of the blocking layer. Furthermore, a comparison of the irreversibility lines between Ca-free and representative Ca-containing Hg-based compounds highlighted that the replacement of Ca by Sr in the CuO2 planes does not significantly impact the temperature dependence of B
irr. Notably, we found that (Hg, Re)Sr2SrCu2O
y
has an irreversibility line as high as that of the reported triple-layered (Hg, Re)Sr2Ca2Cu3O
y
cuprate.
Dendritic flux avalanches in superconducting hybrid structures
Authors: Wasserman M , Shaulov A , Sharoni A , Yeshurun Y
Published: September 2023

Magneto-optical imaging was employed to study dendritic flux avalanches in metal/superconductor and superconductor/superconductor hybrid structures over an extended range of magnetic field ramping rates. Our results in Cu/NbN show that the previously reported suppression of dendritic flux avalanches in metal coated superconducting films is limited to low ramping rates; as the ramping rate increases, the metal coating becomes less and less effective. A more complex behavior is exhibited in superconductor/superconductor hybrid structures. Our measurement in NbN partially coated with Nb, reveal three distinctive types of dendritic avalanches: those propagating in only one layer, either as regular dendrites in the uncoated NbN or as surface dendrites in the Nb layer, and hybrid dendrites that propagate in both the Nb and NbN layers simultaneously. These three types of dendrites are distinguished by their morphology, temperature dependence and instability threshold field. The overall stability of the hybrid structure significantly exceeds that of its weak component.
Bipartite entanglement via distance between the states in a one dimensional spin 1/2 dimer copper acetate monohydrate
Authors: Athira S , L L Silva Saulo , Nag Probal , Lakshmi Sushma , Kumar C Sharath , Prasad Panda Debendra , Das Sayan , Rajput Sarita , P Alex Andrews , Sundaresan A , Reddy Vennapusa Sivaranjana , Maitra T , Jaiswal-Nagar D
Published: September 2023

In this paper, we used a theoretical measure known as distance between the states,

, to determine the bipartite entanglement of a one dimensional magnetic dimer system. The calculation was compared with the well-known entanglement measure, concurrence, and found to be the same.

was, then, expressed in terms of two thermodynamic quantities, namely, magnetic susceptibility and specific heat. Experimental verification of temperature variation of the bipartite entanglement measure in terms of magnetic susceptibility and specific heat was done on single crystals of copper acetate-an excellent one dimensional dimer system. The results showed the existence of bipartite entanglement till temperatures as high as room temperature! Large sized single crystals of copper acetate were grown by a new evaporation technique and characterised by thermogravimetric analysis, IR and Raman spectroscopy measurements. Density functional theory calculations were done to calculate the delocalisation index which showed much lower values of

δ
(

C
u
,
C
u

)

than other bonds, implying that the probability of direct Cu–Cu exchange in copper acetate is very small. Band structure calculations revealed the presence of flat bands at the Fermi level implying very weak intermolecular interactions in copper acetate.
Families of bosonic suppression laws beyond the permutation symmetry principle
Authors: Bezerra M E O , Shchesnovich V S
Published: September 2023

Exact cancellation of quantum amplitudes in multiphoton interferences with Fock states at the input, the so-called suppression or zero transmission laws generalizing the Hong–Ou–Mandel dip, are useful tools in quantum information and computation. It was recently suggested that all bosonic suppression laws follow from a common permutation symmetry both in the input quantum state and in the unitary matrix of the interferometer. By using the recurrence relations for the interference of Fock states, we find a wealth of suppression laws on the beamsplitter and tritter interferometers that do not follow from the permutation symmetry principle. In general, our results point on the existence of whole families of suppression laws with only a fraction of them being accounted for by the permutation symmetry principle, suggested as the general principle behind all the suppression laws.