bluuebunny/crossref_metadata_2025 huggingface dataset:
Computational fluid dynamics simulations of the heat transfer properties of graphene-based nanolubricants and application to hydrodynamic lubrication
Authors: Guarino Roberto , Pugno Nicola Maria
Published: May 2024

In this paper, we consider experimental data available for graphene-based nanolubricants to evaluate their convective heat transfer performance by means of computational fluid dynamics (CFD) simulations. Single-phase models with temperature-dependent properties are employed for this purpose. The base fluid is a polyalkylene glycol, and we show the effect of the addition of carbon nanohorns and graphene nanoplatelets (GNPs), in different volume fractions, on the convective heat transfer coefficient between two parallel plates. Then, an application to hydrodynamic lubrication is discussed. The extreme in-plane thermal conductivity of graphene allows a smaller temperature rise of the GNP-based nanolubricant, i.e., a more effective heat removal. To the best of our knowledge, this work represents the first application of single-phase nanofluid models to hydrodynamic lubrication.
A spin-torque nano-oscillator based on interlayer-coupled meron–skyrmion pairs with a fixed orbit
Authors: Yi Qiyun , Han Ting , Jiang Jinyi , Xing Xiangjun
Published: May 2024

In recent years, magnetic skyrmion-based spin-torque nano-oscillators (STNOs) have attracted considerable interest for their prospect in future-generation communication and spintronic technologies. However, some critical issues, which hamper their practical applications, e.g., the long start-up time and variable skyrmion gyration orbit, remain to be resolved. Here, we numerically demonstrate the realization of a fixed-orbit STNO, which is based on an interlayer-coupled meron–skyrmion (MS) pair instead of a magnetic skyrmion. In this STNO, the MS pair possesses a structurally defined, fixed orbit within a broad range of driving currents, even in the presence of random defects. The output frequency range of the STNO based on an MS pair far exceeds that of the STNO typically featuring a single skyrmion. Moreover, the output frequency of this STNO can be further elevated if more MS pairs are incorporated. Our results reveal the nontrivial dynamics of the interlayer-coupled MS pair, opening perspectives for the design and optimization of fundamental spintronic devices.
Self-pulsing of dielectric barrier discharges at low driving frequencies
Authors: Thagunna Shanti K. , Kolobov Vladimir I. , Zank Gary P.
Published: May 2024

This paper investigates the self-pulsing of dielectric barrier discharges (DBDs) at low driving frequencies. In particular, (a) the dependence of current on the product pd of gas pressure p and the gas gap length d, (b) the effects of lossy dielectrics (in resistive discharges) and large dielectric permittivity (in ferroelectrics) on current dynamics, (c) the transition from Townsend to a dynamic capacitively coupled plasma (CCP) discharge with changing pd values, and (d) the transition from Townsend to a high-frequency CCP regime with increasing the driving frequency. A one-dimensional fluid model of argon plasma is coupled to an equivalent RC circuit for lossy dielectrics. Our results show multiple current pulses per AC period in Townsend and CCP discharge modes which are explained by uncoupled electron–ion transport in the absence of quasineutrality and surface charge deposition at dielectric interfaces. The number of current pulses decreases with an increasing applied frequency when the Townsend discharge transforms into the CCP discharge. The resistive barrier discharge with lossy dielectrics exhibits Townsend and glow modes for the same pd value (7.6 Torr cm) for higher and lower resistances, respectively. Finally, we show that ferroelectric materials can amplify discharge current in DBDs. Similarities between current pulsing in DBD, Trichel pulses in corona discharges, and subnormal oscillations in DC discharges are discussed.
Integral solution method of the laminar conjugated natural convection heat transfer from a hollow cylinder
Authors: Su Xiang , Lin Fuchang , Wang Shengkang , Li Hua
Published: May 2024

The laminar conjugated natural convection heat transfer from a hollow cylinder is a common problem in engineering. The accurate calculation of the hot-spot temperature helps to monitor and evaluate the operating status of the equipment. In this paper, first, a mathematical model of the conjugated natural convection from a hollow cylinder is established. The boundary layer integral equations under arbitrary heat flux distribution on the surface are derived, and the optimal velocity and temperature profiles corresponding to different Prandtl numbers are determined. By combining the integral equations and the thermal network model, the hot-spot temperature and the average surface temperature of a hollow cylinder are solved iteratively. Subsequently, a computational fluid dynamic (CFD) simulation based on finite volume method is carried out to verify the accuracy of the integral solution method. The maximum relative error of the computed results of the two methods is 1.35%. The integral solution method performs much better in computation speed, increasing by 90 times. It is also found that as the thermal conductivity of solid materials decreases, although the hot-spot temperature increases, the average surface temperature remains basically unchanged. Finally, based on the lumped thermal equivalent circuit, the correlation of the Nusselt number corresponding to the hot-spot temperature is predicted. The parameters in the correlation are estimated by regression orthogonal design. The results show that under a wide range of solid thermal conductivity and fluid Prandtl numbers, the maximum error of the correlation is 6.02%. Therefore, this novel method is feasible and significant for calculating hot-spot temperature.
Layer-dependence study of two-dimensional ferromagnets: Fe3GeTe2 and Fe5Ge2Te2
Authors: Alghamdi Mohammed , Jothi Palani R. , Liao Wei-Cheng , Coh Sinisa , Lin Xianqing , Fokwa Boniface P. T. , Shi Jing
Published: May 2024

We have investigated the electrical transport properties of nanodevices fabricated from exfoliated flakes of two-dimensional metallic ferromagnets Fe3GeTe2 (FGT) and Fe5Ge2Te2 (FG2T) down to below three layers in thickness. The per-layer anomalous Hall conductivity even in thick FGT and FG2T devices is found to be much smaller than ∼e2h, the approximate value calculated for thick undoped crystals. Moreover, we obtain a power-law scaling relation between the per-layer anomalous Hall and per-layer longitudinal conductivities with an exponent close to 1.6, which agrees with the universal value for poor ferromagnetic conductors. Both FGT and FG2T devices show clear layer-dependent Curie temperatures and layer-dependent perpendicular magnetic anisotropy, with FG2T dominating the former and FGT dominating the latter for all thicknesses. Despite their declining trend as the device thickness decreases, both Curie temperature and magnetic anisotropy retain a significant fraction of their bulk values (>60% and >80% of the bulk values, respectively, even in the thinnest FG2T device), indicating attractive potential for practical applications.
Precise control of fatigue, wake-up, charge injection, and break-down in Hf0.5Zr0.5O2-based ferroelectric memories
Authors: Liu Nannan , Luo Chunlai , Wu Hongdi , Ding Yecheng , Lu Xubing , Yan Zhibo , Liu Jun-Ming , Yuan Guoliang
Published: May 2024

Hf0.5Zr0.5O2 (HZO) thin films are promising for applications in ferroelectric memories. However, these materials often face challenges, such as polarization fluctuations (e.g., fatigue and wake-up) and electric break-down incidents during the “1/0” write/read cycles, hindering their industrial application. Herein, fatigue, wake-up, and electric break-down seriously depend on both the electric field for polarization switching (Es) and the charge accumulation in the HZO film. More and more charges pin ferroelectric domains, and the sub-switching polarization introduces serious ferroelectric fatigue during the 1010 write/read cycles at Es ∼ 1.2Ec, where Ec is a ferroelectric coercive field. On the contrary, new charges increase rather slowly, and complete polarization switching is realized during the 1010 cycles at Es ∼ 1.5Ec, so the HZO film presents excellent polarization stability. A high Es ∼ 2Ec introduces the strong wake-up effect first; however, the serious charge accumulation largely increases leakage current and quickly introduces an electric break-down of the HZO film. Furthermore, it was found that the leakage current and dielectric permittivity can effectively monitor the charge accumulation and provide an early warning for fatigue and electric break-down.
Calculating the acoustic radiation force on spherical particles in a standing ultrasound wave field considering single and multiple scattering
Authors: Noparast Soheyl , Guevara Vasquez Fernando , Francoeur Mathieu , Raeymaekers Bart
Published: May 2024

Ultrasound directed self-assembly (DSA) utilizes the acoustic radiation force (ARF) associated with a standing ultrasound wave to organize particles dispersed in a fluid medium into specific patterns. The ARF is a superposition of the primary acoustic radiation force, which results from the incident standing ultrasound wave, and the acoustic interaction force, which originates from single and multiple scattering between neighboring particles. In contrast with most reports in the literature that neglect multiple scattering when calculating the ARF, we demonstrate that the deviation between considering single or multiple scattering may reach up to 100%, depending on the ultrasound DSA process parameters and material properties. We evaluate a theoretical case with three spherical particles in a viscous medium and derive operating maps that quantify the deviation between both scattering approaches as a function of the ultrasound DSA process parameters. Then, we study a realistic system with hundreds of particles dispersed in a viscous medium, and show that the deviation between the ARF resulting from single and multiple scattering increases with decreasing particle size and increasing medium viscosity, density ratio, compressibility ratio, and particle volume fraction. This work provides a quantitative basis for determining whether to consider single or multiple scattering in ultrasound DSA simulations.
Full-Stokes polarization detection enabled by a terahertz all-dielectric metasurface
Authors: Zang Huaping , Yang Ziyue , Zhou Xinyi , Liu Jingyu , Li Hui , Yu Qiuchi , Zheng Chenglong , Zhang Yan , Yao Jianquan
Published: May 2024

Metasurface has the ability to flexibly modulate the wavefront and detect the polarization states, thus receiving widespread research attention. The combination of polarization multiplexing techniques and focused beams with polarization information provides a new approach to compact polarization detection behavior. Here, an all-dielectric metasurface based on polarization multiplexing encoding technique is demonstrated and assigns the independent phase distributions to x- and y-polarized channels to separate different polarized components. Combining Stokes parameters and visualized polarization ellipses, realizing one-to-one mapping of the incident polarization states with far-field images. We obtain the Poincaré sphere and visualized polarization ellipses based on Stokes parameters to verify the polarization detection ability of the designed metasurface. The proposed scheme is expected to provide potential applications in fields such as full-Stokes polarization detection, high-resolution imaging, and terahertz communication.
Point mutation in a virus-like capsid drives symmetry reduction to form tetrahedral cages
Authors: Szyszka Taylor N. , Andreas Michael P. , Lie Felicia , Miller Lohra M. , Adamson Lachlan S. R. , Fatehi Farzad , Twarock Reidun , Draper Benjamin E. , Jarrold Martin F. , Giessen Tobias W. , Lau Yu Heng
Published: May 2024

Protein capsids are a widespread form of compartmentalization in nature. Icosahedral symmetry is ubiquitous in capsids derived from spherical viruses, as this geometry maximizes the internal volume that can be enclosed within. Despite the strong preference for icosahedral symmetry, we show that simple point mutations in a virus-like capsid can drive the assembly of unique symmetry-reduced structures. Starting with the encapsulin fromMyxococcus xanthus, a 180-mer bacterial capsid that adopts the well-studied viral HK97 fold, we use mass photometry and native charge detection mass spectrometry to identify a triple histidine point mutant that forms smaller dimorphic assemblies. Using cryoelectron microscopy, we determine the structures of a precedented 60-mer icosahedral assembly and an unexpected 36-mer tetrahedron that features significant geometric rearrangements around a new interaction surface between capsid protomers. We subsequently find that the tetrahedral assembly can be generated by triple-point mutation to various amino acids and that even a single histidine point mutation is sufficient to form tetrahedra. These findings represent a unique example of tetrahedral geometry when surveying all characterized encapsulins, HK97-like capsids, or indeed any virus-derived capsids reported in the Protein Data Bank, revealing the surprising plasticity of capsid self-assembly that can be accessed through minimal changes in the protein sequence.
HERC3 facilitates ERAD of select membrane proteins by recognizing membrane-spanning domains
Authors: Kamada Yuka , Ohnishi Yuko , Nakashima Chikako , Fujii Aika , Terakawa Mana , Hamano Ikuto , Nakayamada Uta , Katoh Saori , Hirata Noriaki , Tateishi Hazuki , Fukuda Ryosuke , Takahashi Hirotaka , Lukacs Gergely L. , Okiyoneda Tsukasa
Published: May 2024

Aberrant proteins located in the endoplasmic reticulum (ER) undergo rapid ubiquitination by multiple ubiquitin (Ub) E3 ligases and are retrotranslocated to the cytosol as part of the ER-associated degradation (ERAD). Despite several ERAD branches involving different Ub E3 ligases, the molecular machinery responsible for these ERAD branches in mammalian cells remains not fully understood. Through a series of multiplex knockdown/knockout experiments with real-time kinetic measurements, we demonstrate that HERC3 operates independently of the ER-embedded ubiquitin ligases RNF5 and RNF185 (RNF5/185) to mediate the retrotranslocation and ERAD of misfolded CFTR. While RNF5/185 participates in the ERAD process of both misfolded ABCB1 and CFTR, HERC3 uniquely promotes CFTR ERAD. In vitro assay revealed that HERC3 directly interacts with the exposed membrane-spanning domains (MSDs) of CFTR but not with the MSDs embedded in liposomes. Therefore, HERC3 could play a role in the quality control of MSDs in the cytoplasm and might be crucial for the ERAD pathway of select membrane proteins.
Scalar perturbations in nonsingular universes from interacting vacuum
Authors: Alves Filipe Cattete , Maier Rodrigo
Published: May 2024

In this paper we examine the stability of scalar perturbations in nonsingular models which emerge from an interacting vacuum component. The analysis developed in this paper relies on two phenomenological choices for the energy exchange between a nonrelativistic fluid and a vacuum component. In both scenarios it can be shown that closed models may furnish nonsingular orbits of physical interest in phase space once a decelerated past era is connected to a graceful exit to late-time acceleration. Regarding such configurations as background spacetimes we introduce scalar perturbations in order to examine the stability of these models in a high energy domain. We explicitly show that the vacuum perturbation is not an independent variable and diverges as dynamics approaches the bounce. This feature assigns a rather unstable signature to the dynamics making the choices for the energy transfer ill defined at least for nonsingular configurations at the bounce scale.
Capacitor connected to an alternating voltage: Maxwell’s equations, Poynting’s theorem and oscillating L-C circuits
Authors: Beléndez A , Sirvent-Verdú J J , Lloret T , García-Vázquez J C , Ramírez-Vázquez R , Marini S
Published: May 2024

The behaviour of a parallel-plate capacitor connected to a sinusoidal alternating voltage is analysed and the electric and magnetic fields, as well as the electric and magnetic energies inside the capacitor are obtained. Aspects related to Maxwell’s equations, the Poynting vector and the conservation of electromagnetic energy are also discussed. Under certain conditions the electromagnetic energy stored in the capacitor remains constant and the behaviour of the capacitor at high frequencies is like that of an oscillating L-C circuit consisting of an inductor and a capacitor. The general situation is considered, valid for both low and high frequencies, and what is discussed here is of interest to students of an undergraduate electrodynamics course.
Stability and statistical inversion of travel time tomography
Authors: Tarikere Ashwin , Zhou Hanming
Published: May 2024

In this paper, we consider the travel time tomography problem for conformal metrics on a bounded domain, which seeks to determine the conformal factor of the metric from the lengths of geodesics joining boundary points. We establish forward and inverse stability estimates for simple conformal metrics under some a priori conditions. We then apply the stability estimates to show the consistency of a Bayesian statistical inversion technique for travel time tomography with discrete, noisy measurements.
Strong hybridization of Nb2C with MoS2: a way to reduce contact resistance
Authors: Zan Jinxin , Wang Huan , Tao Bairui , Liu Xiaojie , Wang Yin , Yin Haitao
Published: May 2024

The hybridization of MXene materials and transition metal dichalcogenides has a significant impact on heterojunction properties. The transport properties and electronic structure of heterojunctions of semiconducting MoS2 and metallic MXene Nb2C were studied by integrating density functional theory with non-equilibrium Green’s function theory. The hybridization between Nb2C and MoS2 makes the tunneling barrier between the two layers disappear, which can enhance the electron injection efficiency from the Nb2C to the MoS2. Moreover, the Nb2C/MoS2 heterojunction exhibits a conventional n-type Schottky contact with a barrier height of 0.14 eV, which is significantly lower than the barrier height of 0.29 eV at the Ti/MoS2 junction. These factors result in a field-effect transistor with a low contact resistance of 138 Ω·μm and a higher current of 1.09 mA μm−1 at a bias voltage of 0.3 V applied between the left and right electrodes. Following the application of gate voltage, the I
on/I
off ratio reaches 1266.
Controllable defects in monolayer graphene induced by hydrogen and argon plasma
Authors: Huang Xianlei , Wan Zihao , Yuan Guowen , Zhou Zhenjia , Gao Libo
Published: May 2024

Graphene has attracted wide attentions since its successfully exfoliation. Honeycomb sp
2 carbon lattice and Dirac semi-metal band structure make graphene a promising material with excellent mechanical strength, thermal conductivity, and carrier mobility. However, the absence of intrinsic bandgap limits its application in semiconductor. Defects in graphene is supposed to modify its band structure and lead to an opened bandgap. Many methods have been demonstrated to introduce defects into graphene, such as chemical reaction, plasma, electron beam, and laser. However, the species of defects are mostly uncontrollable in most treatment processes. In this study, we report three kinds of defects can be controllably induced in graphene via hydrogen (H2) and argon (Ar) plasma. With different parameter and feeding gas, hydrogenated graphene, graphene nanomesh and graphene with vacancies can be well obtained. The defect density can be precisely controlled by tuning plasma power and irradiation time. Morphological, spectroscopic, and electrical characterizations are performed to systematically investigate the defect evolution. Graphene nanomesh and graphene with vacancies show obvious difference for roughness and coverage, whereas the morphology of hydrogenated graphene remains similar with that of as-prepared graphene. For hydrogenated graphene, an opened bandgap of ∼20 meV is detected. For graphene nanomesh and graphene with vacancies, the semiconductive on/off behaviors are observed. We believe this work can provide more details of plasma-induced defects and assist the application of graphene in semiconductor industry.
Awareness of disaster preparedness between administrative staff and residents in the vicinity of the Genkai and Ikata nuclear power plants following the Fukushima Daiichi nuclear power plant disaster
Authors: Yamamoto Chika , Sawano Toyoaki , Eguchi Yuichiro , Fukazawa Shinya , Zhao Tianchen , Ochi Genro , Tsubokura Masaharu
Published: May 2024

When considering disaster preparedness, one challenge is mitigating the health impacts of evacuations. Nuclear disaster preparedness has evolved based on past experiences from numerous disasters, including the Fukushima Daiichi Nuclear Power Plant (FDNPP) accident. However, there is a lack of comprehensive reporting on the awareness of administrative staff, medical personnel, and residents in the areas surrounding nuclear power plants (NPPs). This study reports on a survey aimed at gaining insights into the understanding and current state of disaster preparedness and elucidating the differences in perceptions of nuclear disaster preparedness among the relevant stakeholders surrounding NPPs. Interview surveys were conducted from 14 to 16 September 2022 in the area surrounding Kyushu Electric Power’s Genkai NPP in Saga Prefecture and from 11 to 13 January 2023 in the area around Shikoku Electric Power’s Ikata NPP. The surveys targeted administrative, medical, and nursing care facilities and residents. Responses from 57 participants indicated a lack of awareness of natural and nuclear disasters, challenges in evacuation planning, and a gap between nuclear disaster training and residents’ understanding of evacuation protocols. This study highlights inadequacies in nuclear disaster preparedness and the need for a better understanding among residents regarding evacuation procedures. This study identified three key issues: (1) a lack of awareness about disasters, including nuclear disasters; (2) concerns about complex disasters and the difficulties in creating evacuation plans; and (3) a discrepancy between nuclear disaster training and residents’ understanding of evacuation procedures. To bridge this gap, it is important to deepen residents’ understanding of nuclear disasters, continuously convey the lessons learned from the FDNPP accident, and regularly reassess and update nuclear disaster preparedness strategies.
Step height measurement of monoatomic silicon crystal lattice steps with a commercial atomic force microscope
Authors: Lawn Malcolm A , Bolton Zoe , Murphy Layne , Gartner Samuel , Oh Yechan , Coleman Victoria A
Published: May 2024

Precise control of advanced materials relies on accurate dimensional metrology at the sub-nanometre scale. At this scale, the accuracy of scanning probe microscopy (SPM) has been limited by the lack of traceable transfer standard artefacts with calibration structures of suitable dimensions. With the adoption in 2019 of the silicon crystal lattice spacing as a secondary realization of the metre in the International System of Units (SI), SPM users have direct access to a realization of the SI metre at the sub-nanometre level by means of the step height of self-assembled monatomic lattice steps that can form on the surface of silicon crystals. A key challenge of successfully adopting this pathway is establishing protocols to minimize measurement errors and artefacts in routine laboratory use. In this study, step height measurements of monoatomic lattice steps in an ordinal/staircase structure on a Si(111) crystal surface have been derived from images acquired with a commercially available, research-level atomic force microscope (AFM). Measurement results derived from AFM images using three different SPM image processing and analysis software packages are compared. Significant sources of measurement uncertainty are identified, principally the contribution from the dependence on scan direction. The calibration of the AFM derived from this measurement was used to traceably measure the sub-nanometre lattice steps on a silicon carbide crystal surface to demonstrate the viability of this calibration pathway.
Motor online novelty detection scheme based on one-class hyperdisk
Authors: Yang Bin , He Zhiyi , Shao Haidong , Xu Xiaoqiang
Published: May 2024

Online novelty detection is of great importance in the series production of motors. This study developed an online novelty detection scheme for motors based on a one-class hyperdisk (OCHD) model. In the OCHD approach, the decision boundary is estimated using a hyperdisk (HD), which is derived from the training sample set. The HD model addresses the underestimation issue commonly associated with convex-hull-based methods by providing a more accurate estimation of the class region. Furthermore, an optimal separating hyperplane is constructed at the nearest point on the HD by solving a quadratically constrained quadratic program problem. Statistical features refined by the Laplacian score are employed in the proposed novelty detection scheme. This study introduces an online novelty detection scheme for assessing motor quality in actual series production. The test results from the offline experiment demonstrate the superiority of the OCHD method. Datasets collected at the end of the production line were evaluated using the proposed novelty detection scheme. The inspection results for motor components confirm that the proposed method effectively identifies faulty motors during the series production process.
Modification of WS2 thin film properties using high dose gamma irradiation
Authors: Jadhav P R , Kolhe P T , Ghemud V S , Shelke P N , Patole S P , Dhole S D , Dahiwale S S
Published: May 2024

The tunability of the transition metal dichalcogenide properties has gained attention from numerous researchers due to their wide application in various fields including quantum technology. In the present work, WS2 has been deposited on fluorine doped tin oxide substrate and its properties have been studied systematically. These samples were irradiated using gamma radiation for various doses, and the effect on structural, morphological, optical and electrical properties has been reported. The crystallinity of the material is observed to be decreased, and the results are well supported by x-ray diffraction, Raman spectroscopy techniques. The increase in grain boundaries has been supported by the agglomeration observed in the scanning electron microscopy micrographs. The XPS results of WS2 after gamma irradiation show evolution of oxygen, carbon, C=O, W–O and SO4
−2 peaks, confirming the addition of impurities and formation of point defect. The gamma irradiation creates point defects, and their density increases considerably with increasing gamma dosage. These defects crucially altered the structural, optical and electrical properties of the material. The reduction in the optical band gap with increased gamma irradiation is evident from the absorption spectra and respective Tauc plots. The I–V graphs show a 1000-fold increase in the saturation current after 100 kGy gamma irradiation dose. This work has explored the gamma irradiation effect on the WS2 and suggests substantial modification in the material and enhancement in electrical properties.
Line and load regulation: a microcontroller-based experiment
Authors: Önder Fatih
Published: May 2024

Voltage regulators, the most common application of Zener diodes, are included in many electronic devices we use in our daily lives. Therefore, students need to learn about regulators to understand the place of Zener diodes in modern electronic technologies. This study focuses on a microcontroller-based experiment that can be used to teach line and load regulation with real-time graphics. The main advantage of the designed experiment over its classical equivalent is its ability to display autonomous and real-time data display. It also eliminates the problem of determining the load resistance, which is the main difficulty of the classical experiment.
Kinematics of the barn-pole paradox
Authors: Binder P-M
Published: May 2024

Several ways are shown to solve this famous paradox of special relativity, including two that involve calculations exclusively in one of the inertial frames.
Taking on a new meaning of physics mathematization for teaching in teacher education processes
Authors: Castiblanco Abril Olga Lucía , Vizcaíno Arévalo Diego Fabián
Published: May 2024

This is a documented reflection that seeks to characterize an alternative conception of the ‘mathematization of physics for teaching’. The reflection was made on the academic production of the research group ‘Teaching and learning of physics’. This group has posed a sequence of research questions has been raised to find out how physics teachers understand the relationship between physics and mathematics in the physics teaching process. In 2003 they studied the idea of ‘mathematical beauty’ in the early days of quantum mechanics, suggesting that there would be a difference between the way scientists assume the physical/mathematical relationship and the way physics is taught. In 2010, they wondered if there would be research in this field that would allow transformations in teaching focused on equations as the set of mathematical–physical relationships, finding that there are at least three trends. In 2019, they verified that despite the research in the literature, many students continue with the same reductionist idea about this relationship. In 2020, they made a proposal, showing a possibility of educating the teacher’s thinking for new understandings in this regard. The main conclusion is that it is possible to develop mathematization processes in the classroom from three specific phases that educate scientific thinking. The first phase tries to make the student aware of the existence of phenomenology and describe it. The second phase educates the study of nature in a systematic way, building the meaning of the organization of a physical system. The third phase promotes explanation and argument so that students achieve an explanatory model. These phases are configured as a criterion to guide the sequence of activities in a class, a set of classes or a complete course and have been worked on and tested in ‘physics didactics’ courses in a physics teacher training course.
An indirect estimation of x-ray spectrum via convolutional neural network and transmission measurement
Authors: Lv Tie , Xu Shouping , Wang Yanxin , Zhang Gaolong , Niu Tianye , Liu Chunyan , Sun Baohua , Geng Lisheng , Zhu Lihua , Zhao Wei
Published: May 2024

Objective. In this work, we aim to propose an accurate and robust spectrum estimation method by synergistically combining x-ray imaging physics with a convolutional neural network (CNN). Approach. The approach relies on transmission measurements, and the estimated spectrum is formulated as a convolutional summation of a few model spectra generated using Monte Carlo simulation. The difference between the actual and estimated projections is utilized as the loss function to train the network. We contrasted this approach with the weighted sums of model spectra approach previously proposed. Comprehensive studies were performed to demonstrate the robustness and accuracy of the proposed approach in various scenarios. Main results. The results show the desirable accuracy of the CNN-based method for spectrum estimation. The ME and NRMSE were −0.021 keV and 3.04% for 80 kVp, and 0.006 keV and 4.44% for 100 kVp, superior to the previous approach. The robustness test and experimental study also demonstrated superior performances. The CNN-based approach yielded remarkably consistent results in phantoms with various material combinations, and the CNN-based approach was robust concerning spectrum generators and calibration phantoms. Significance. We proposed a method for estimating the real spectrum by integrating a deep learning model with real imaging physics. The results demonstrated that this method was accurate and robust in estimating the spectrum, and it is potentially helpful for broad x-ray imaging tasks.
A new model of thermo-mechanical actuation for twisted and coiled polymer muscles with initial curvature
Authors: Liu Lei , Liu Hao , Zhang Zhiya , Liu Dabiao
Published: May 2024

The twisted and coiled polymer (TCP) artificial muscle is one type of novel soft actuator for mimicking natural skeletal muscle that can provide large linear and torsional actuation and energy density. Twisting and coiling are the pivotal steps in fabricating TCP muscles. The influence of twisting on the actuation response of TCP muscles has been extensively investigated recently. However, the influence of coiling remains unclear. Based on the finite strain theory, we establish a new thermo-mechanical actuation model for TCP muscles with initial curvature. The theoretical predictions based on the model align well with the finite element simulations, accurately capturing the actuation response of thermally-activated TCP muscles. It is revealed that twisting contributes positively to the actuation, while coiling has a passive effect. Geometrical parameters, such as the helix radius and helix angle, can effectively regulate the actuation performance of TCP muscles. Furthermore, an optimal bias angle is identified that maximizes both the recovery torque and the linear actuation. This study sheds light on the structural optimization design of TCP muscles.
Design and performance analysis of high-speed on/off valve based on energy-coupled actuator
Authors: Dai Jin , Yang Chenghao , Xiong Shaoping
Published: May 2024

The development digital hydraulics demands higher performance on high-speed on/off valves. In order to fully exploit the energy saving advantages of digital hydraulics, advanced high-speed valves are expected to possess a fast response and a large nominal flow rate simultaneously. Energy-coupled-actuator (ECA) utilizes the shear working mode of magnetic rheological fluid to achieve reciprocating motion of the valve spool through the coupling/decoupling of a pair of disks and a translational piece and its driving force is not affected by the valve spool’s position. The reported advantages of ECA meets the design requirements of actuators for high-speed on/off valve. This study gives the detailed design proposal of high-speed valve based on ECA (ECAV). The work also established a multi-physics coupled model for ECAV, calculated the key parameters of the valve driving system, and predicted the switching performance of ECAV. Finally, a prototype of ECAV with updated sealing solution between the actuator and valve block was fabricated and experimental tested. The results indicate that for current ECAV prototype successfully established 40 l min−1@5 bar (1.5 mm stroke) using response time less than 7 ms. Moreover, the prototype only consumed 14 ms to reach a long stroke of 5 mm with a significantly increased ratio of stroke over response time.
Topological pumping induced by spatiotemporal modulation of interaction
Authors: Huang Boning , Ke Yongguan , Liu Wenjie , Lee Chaohong
Published: May 2024

Particle-particle interaction provides a new degree of freedom to induce novel topological phenomena. Here, we propose to use spatiotemporal modulation of interaction to realize topological pumping without a single-particle counterpart. Because the modulation breaks time-reversal symmetry, the multiparticle energy bands of bound states have none-zero Chern number, and support topological bound edge states. In a Thouless pump, a bound state that uniformly occupies a topological energy band can be shifted by integer unit cells per cycle, consistent with the corresponding Chern number. We can also realize topological pumping of bound edge state from one end to another. The entanglement entropy between particles rapidly increases at transition points, which is related to the spatial spread of a bounded pair. In addition, we propose to realize hybridized pumping with fractional displacement per cycle by adding an extra tilt potential to separate topological pumping of the bound state and Bloch oscillations of single particle. Our work could trigger further studies of correlated topological phenomena that do not have a single-particle counterpart.
A basic examination of the gauged model of the Floreanini-Jackiw chiral boson within the framework of BRST symmetry
Authors: Ghoshal Sanjib , Rahaman Anisur
Published: May 2024

We consider the gauged model of Floreanini-Jackiw chiral boson which is generated from the chiral boson with parameter-free Faddeevian anomaly. This model does not have a manifestly Lorentz co-variant structure. However, it is exactly solvable and has a physical subspace that is precisely Lorentz invariant. The recommendation of Mitra and Rajaraman makes this model gauge invariant in the usual phasespace. Additionally, Wess-Zumino terms for this model are constructed to make it gauge-invariant which allows BRST embedding of the resulting gauge-invariant theory. Despite the strange structural appearance of the models when viewed in terms of Lorentz covariance BRST invariant reformulation has been found possible. Additionally, it has been observed that being supplemented with BRST symmetry, anti-BRST symmetry plays a crucial role in pinpointing the specific symmetric physical states.
A conceptual review on Bessel beams
Authors: Rao A Srinivasa
Published: May 2024

Over the past 36 years much research has been carried out on Bessel beams (BBs) owing to their peculiar properties, viz non-diffraction behavior, self-healing nature, possession of well-defined orbital angular momentum with helical wave-front, and realization of smallest central lobe. Here, we provide a detailed review on BBs from their inception to recent developments. We outline the fundamental concepts involved in the origin of the BB. The theoretical foundation of these beams was described and then their experimental realization through different techniques was explored. We provide an elaborate discussion on the different kinds of structured modes produced by the BB. The advantages and challenges that come with the generation and applications of the BB are discussed with examples. This review provides reference material for readers who wish to work with non-diffracting modes and promotes the application of such modes in interdisciplinary research areas.
Statistical conformal Killing vector fields for FLRW space-time
Authors: Peyghan E , Nourmohammadifar L , Iosifidis D
Published: May 2024

The classification of conformal Killing vector fields for FLRW space-time from Riemannian point of view was done by Maartens-Maharaj in [1]. In this paper, we introduce conformal Killing vector fields from a new point of view for the FLRW space-time. In particular, we consider three cases for the conformal factor. Then, it is shown that there exist nine conformal vector fields on FLRW in total, such that six of them are Killing and the rest being non-Killing conformal vector fields. Consequently, by recalling the concept of statistical conformal Killing vector fields introduced in [2], we classify statistical structures whith repsect to which these vector fields are conformal Killing. We also obtain the form of affine connections that feature a vanishing Lie derivative with respect to these conformal Killing vector fields. Imposing the torsion-free and the Codazzi conditions on these connections, we study statistical structures on FLRW. Finally, for torsionful connections we study the vanishing of the Lie derivative of the torsion tensor with respect to these conformal Killing vector fields and derive the conditions under which this is valid.
Design and sensitivity analysis of GAA nanowire dopingless FET based label free biosensor
Authors: Solay Leo Raj , Kumar Naveen , Singh Sarabdeep , Amin S Intekhab , Yuvaraja Saravanan , Anand Sunny
Published: May 2024

This paper proposes a highly sensitive nanoscale label-free biosensor upon charge plasma based gate-all-around nanowire dopingless field effect transistor (GAA NW DL FET Biosensor) for the detection of biomolecules. The proposed sensor device structure employs charge plasma and dopingless approaches to eliminate the requirement for doping. The thermionic emission of FET structures increases the device’s current sensitivity (SI) for various targeted biomolecules introduced through the nanocavity created at the source side/metal of the proposed biosensor. To test the significant sensing performance of the device proposed herein, the biomolecules streptavidin with a dielectric constant (K) of 2.1, 3-aminopropyltriethoxysilane (APTES) with a K value of 3.57, and protein with a K value of 8 are utilized. The proposed sensor resulted in drain current sensitivity as high as 1.4 of protein biomolecule. An extensive analysis was performed to evaluate the efficiency of the proposed sensor with process-related issues such as cavity length variations ranging from 21 nm to 3 nm and real-time related issues such as fill factor variations ranging from 20% to 100% and interface charges for the targeted biomolecules, and their sensitivity parameters were investigated, demonstrating the promising features of GAA NW DL FET biosensor as an ultrasensitive biosensor for clinical applications.
Investigation of negative differential resistance on negative capacitance Germanium source vertical TFET
Authors: Vanlalawmpuia K
Published: May 2024

In this article, a systematic investigation of negative differential resistance (NDR) on a negative capacitance Germanium source vertical TFET (NC-Ge-vTFET) is presented. The implementation and increased ferroelectric (FE) film thickness (t
FE) offers a significantly high current ratio, improved subthreshold slope, high transconductance with a very low hysteresis voltage. However, NDR is exhibited and is increasingly prominent at lower gate voltage and higher t
FE due to the coupling of the internal gate and drain voltages. NDR is an undesired effect in analog circuits that has to be mitigated. To suppress the impacts of NDR on the device, different approaches are carried out: varying the overlap channel thickness, gate length, drain doping and gate-drain underlap. Circuit analysis is carried out with the implementation of NC-Ge-vTFET as digital inverter. When the gate-drain underlap length is increased from 0 nm to 15 nm, the propagation delay is significantly reduced by 30.98%. Benchmarking of the proposed device has also been carried out. This renders the gate-drain underlapped NC-Ge-vTFET to be a viable candidate for high performance, nanoscale, low power digital applications.
Regulation of monolayer MgGeN2 thin film with uniaxial and biaxial strain
Authors: Yu Yi , Chen Kai , Chang Xiangrong , Ma Xiumin , Pan Min , Chu Longsheng , Hu Chunfeng , Feng Qingguo
Published: May 2024

The regulation of electronic and optical properties with uniaxial and biaxial strain is computationally investigated for the monolayer thin film of a newly discovered quasi-layered MgGeN2 phase. It is found that, under uniaxial compression in both [100] and [010] directions with the perpendicular lattice parameter relaxable, the band gap will first increases and then decreases, while under uniaxial tensile strain the band gap decreases monotonically and the light absorption in the visible region is strongly enhanced. When uniaxial compression was applied with the perpendicular lattice constant fixed, the band gap behaves like the first kind of uniaxial compression and the light absorption is enhanced in visible range by compression. When biaxial strain was applied, the band gap shows a monotonic decrease from the largest compression down to the largest tensile strain, while the light absorption behaves in the opposite way. Therefore, the band structure and light absorption of monolayer MgGeN2 can be efficiently tuned with strain and stress, which can potentially be used for the MgGeN2 film in device design, thus promoting its applications in optoelectronics and photocatalysis.
Imprints of light dark matter on the evolution of cosmic neutrinos
Authors: Wang Isaac R. , Xu Xun-Jie
Published: May 2024

Neutrinos are often considered as a portal to new physics beyond the Standard Model (SM) and might possess phenomenologically interesting interactions with dark matter (DM). This paper examines the cosmological imprints of DM that interacts with and is produced from SM neutrinos at temperatures below the MeV scale. We take a model-independent approach to compute the evolution of DM in this framework and present analytic results which agree well with numerical ones. Both freeze-in and freeze-out regimes are included in our analysis. Furthermore, we demonstrate that the thermal evolution of neutrinos might be substantially affected by their interaction with DM. We highlight two distinctive imprints of such DM on neutrinos: (i) a large, negative contribution to N
eff, which is close to the current experimental limits and will readily be probed by future experiments; (ii) spectral distortion of the cosmic neutrino background (CνB) due to DM annihilating into neutrinos, a potentially important effect for the ongoing experimental efforts to detect CνB.
The separate-universe approach and sudden transitions during inflation
Authors: Jackson Joseph H.P. , Assadullahi Hooshyar , Gow Andrew D. , Koyama Kazuya , Vennin Vincent , Wands David
Published: May 2024

The separate-universe approach gives an intuitive way to understand the evolution of
cosmological perturbations in the long-wavelength limit. It uses solutions of the
spatially-homogeneous equations of motion to model the evolution of the inhomogeneous universe on
large scales. We show that the separate-universe approach fails on a finite range of super-Hubble
scales at a sudden transition from slow roll to ultra-slow roll during inflation in the very early
universe. Such transitions are a feature of inflation models giving a large enhancement in the
primordial power spectrum on small scales, necessary to produce primordial black holes after
inflation. We show that the separate-universe approach still works in a piece-wise fashion, before
and after the transition, but spatial gradients on finite scales require a discontinuity in the
homogeneous solution at the transition. We discuss the implications for the δN formalism
and stochastic inflation, which employ the separate-universe approximation.
The Adjustment Analysis Method of the Active Surface Antenna Based on Convolutional Neural Network
Authors: Ban You , Shi Shang , Wang Na , Xu Qian , Feng Shufei
Published: May 2024

Active surface technique is one of the key technologies to ensure the reflector accuracy of the millimeter/submillimeter wave large reflector antenna. The antenna is complex, large-scale, and high-precision equipment, and its active surfaces are affected by various factors that are difficult to comprehensively deal with. In this paper, based on the advantage of the deep learning method that can be improved through data learning, we propose the active adjustment value analysis method of large reflector antenna based on deep learning. This method constructs a neural network model for antenna active adjustment analysis in view of the fact that a large reflector antenna consists of multiple panels spliced together. Based on the constraint that a single actuator has to support multiple panels (usually 4), an autonomously learned neural network emphasis layer module is designed to enhance the adaptability of the active adjustment neural network model. The classical 8-meter antenna is used as a case study, the actuators have a mean adjustment error of 0.00252 mm, and the corresponding antenna surface error is 0.00523 mm. This active adjustment result shows the effectiveness of the method in this paper.