bluuebunny/crossref_metadata_2025 huggingface dataset:
Unravelling the electrochemical impedance spectroscopy of silicon half cells with commercial loading
Authors: Huld Frederik T. , Yu Zhixin , Lou Fengliu
Published: June 2023

EIS is performed on high loading commercial Si electrodes half cells are found to be strongly dependent on the Li counter electrode. Li is found to dominate the EIS spectrum of Si half cells at potentials below 0.07 V and above 0.48 V vs. Li/Li+.
Silicon atom doping in heterotrimetallic sulfides for non-noble metal alkaline water electrolysis
Authors: Hegazy Mohamed Barakat Zakaria , Bahri Leila , Tetzlaff David , Sanden Sebastian A. , Apfel Ulf-Peter
Published: June 2023

The engineering of a pentlandite (Fe3Co3Ni3S8, FCNS) doped with silicon (FCNSSi) for water splitting is demonstrated. At 500 mA cm−2, a two-electrode zero-gap cell assembly demonstrates the FCNSSi catalyst's promise for practical applications.
A novel self‐timing CMOS first‐edge take‐all circuit for on‐chip communication systems
Authors: Abdelhafeez Saleh , Harb Shadi M. S.
Published: June 2023

In today's communication systems, it has become prominent for processing elements (PEs) to receive requests with simultaneous, conflicting signals, which are unpredicted and randomly triggered. In such a case, multiple overlapping signal requests can potentially compete in the same PE causing erroneous operations or a halt of the communication cycle. The authors propose a self‐timing CMOS first‐edge take‐all (FETA) circuit architecture, which examines two overlapping signals’ requests, and outputs only the leading‐edge signal while the lagging‐edge signal's request is declined. The FETA circuit functionality is considered as an essential component in First‐In‐First‐Out for metastability avoidance, which usually occurs between the write and read overlapping requests for applications related to Internet of Things, Network‐on‐Chips, and microprocessor memory management units. HSPICE simulations for a 90 nm CMOS technology are used to verify the speed up to 1 GHz. Besides, the achievable resolution is in the order of 20 ps considering process variation sensitivity based on design inheriting symmetric timing paths between the two signals. Additionally, the proposed circuit architecture adopts a self‐timing scheme obviating the overhead synchronisation circuitry, which comprises 12 D‐Type Flip‐Flops with about 300 transistors. This design is suited for HDL synthesis and FPGA application features.
Transient stability versus damping of electromechanical oscillations in power systems with embedded multi‐terminal VSC‐HVDC systems
Authors: Renedo Javier , Rouco Luis , Garcia‐Cerrada Aurelio , Sigrist Lukas
Published: June 2023

Multi‐terminal high‐voltage direct current technology based on voltage‐source converter stations (VSC‐MTDC) is expected to be one of the most important contributors to the future of electric power systems. In fact, among other features, it has already been shown how this technology can contribute to improve transient stability in power systems by the use of supplementary controllers. Along this line, this paper will investigate in detail how these supplementary controllers affect electromechanical oscillations, by means of small‐signal stability analysis. The paper analyses two control strategies based on the modulation of active‐power injections (P‐WAF) and reactive‐power injections (Q‐WAF) in the VSC stations which were presented in previous work. Both control strategies use global signals of the frequencies of the VSC‐MTDC system and they presented significant improvements on transient stability. The paper will provide guidelines for the design of these type of controllers to improve both large‐ and small‐disturbance angle stability. Small‐signal stability analysis (in Matlab) has been compared with non‐linear time domain simulation (in PSS/E) to confirm the results using CIGRE Nordic32A benchmark test system with a VSC‐MTDC system. The paper analyses the impact of the controller gains and communication latency on electromechanical‐oscillation damping. The main conclusion of the paper is that transient‐stability‐tailored supplementary controllers in VSC‐MTDC systems can be tuned to damp inter‐area oscillations too, maintaining their effectiveness.
River boundary detection and autonomous cruise for unmanned surface vehicles
Authors: Zhang Kai , Hu Min , Ren Fuji , Bao Yanwei , Shi Piao , Yu Daoyang
Published: June 2023

The detection of river boundaries is a crucial branch of the intelligent perception of unmanned surface vehicles (USVs), it can be used to determine the driving areas of USVs, and also to ensure driving safety by limiting the effective drivable areas of USVs in the river areas. Aiming to detect the boundaries of incompletely structured river channels, this study proposes a real‐time detection method for river boundaries based on a Light Detection and Ranging (LiDAR) sensor. The point clouds that are disturbed by the water surface noise are filtered firstly, and then the spatial and geometric features are extracted separately from the point cloud detected above the water surface. To prevent the error detection and missing detection, the boundary point information is predicted and calibrated in real time by Extended Kalman Filter (EKF). A planning track generation algorithm for coastal autonomous cruise without relying on high‐precision maps, and a heading and distance adaptive control method by Proportional‐Integral‐Derivative (PID), and different driving line generation methods for driving along the narrow river and wide river are proposed respectively. The experimental data verification of river boundary detection shows that the algorithm is accurate, real‐time, and robust.
Formal verification of a telerehabilitation system through an abstraction and refinement approach using Uppaal
Authors: Arfi Farid , Courbis Anne‐Lise , Lambolais Thomas , Bughin François , Hayot Maurice
Published: June 2023

Formal methods are proven techniques that provide a rigorous mathematical basis to software development. In particular, they allow the quality of development to be effectively improved by making accurate and explicit modelling, so that anomalies like ambiguities and incompleteness are identified in the early phases of the software development process. Semi‐formal UML models and formal Timed Automata models are used to design a telerehabilitation system through a practical approach based on abstraction and refinement. The formal verification of expected properties of the system is performed by the Uppaal tool. The motivation of this work is threefold: (i) showing the usefulness of formal methods to satisfy the validation needs of a medical telerehabilitation system; (ii) demonstrating our approach of system analysis through refinements to guide the development of a complex system; and (iii) highlighting, from a real‐life experience, the usefulness of models to involve the stakeholders all along the design of a system, from requirements to detailed specifications.
Mapping the complex evolution of ferroelastic/ferroelectric domain patterns in epitaxially strained PbTiO3 heterostructures
Authors: Lichtensteiger Céline , Hadjimichael Marios , Zatterin Edoardo , Su Chia-Ping , Gaponenko Iaroslav , Tovaglieri Ludovica , Paruch Patrycja , Gloter Alexandre , Triscone Jean-Marc
Published: June 2023

We study the complex ferroelastic/ferroelectric domain structure in the prototypical ferroelectric PbTiO3 epitaxially strained on (110)o-oriented DyScO3 substrates, using a combination of atomic force microscopy, laboratory and synchrotron x-ray diffraction, and high resolution scanning transmission electron microscopy. We observe that the anisotropic strain imposed by the orthorhombic substrate creates a large asymmetry in the domain configuration, with domain walls macroscopically aligned along one of the two in-plane directions. We show that the periodicity as a function of film thickness deviates from the Kittel law. As the ferroelectric film thickness increases, we find that the domain configuration evolves from flux-closure to a/c-phase, with a larger scale arrangement of domains into superdomains.
Consolidation and properties of porous Cu–Al–Ni shape memory alloys manufactured by powder metallurgy
Authors: Gómez A. P. , Urretavizcaya G. , Baruj A. L. , Malachevsky M. T.
Published: June 2023

A method to manufacture a porous Cu–Al–Ni shape memory alloy by powder metallurgy using space holders is presented. Two aluminium powders with different particle morphologies were employed to investigate their influence on phase formation, microstructure and mechanical properties. The variation of the relative amount of space holders in the mixture allows to obtain different porosities. Samples prepared with irregular-shaped aluminium powder include both 18R and 2H martensitic phases and exhibit the shape memory effect and pseudoelastic behaviour under uniaxial compression tests. In contrast, the samples made with aluminium flakes present the α phase accompanying the 18R martensitic phase, and do not exhibit the shape memory effect. Both the aluminium flakes flat shape and the higher proportion of aluminium oxide associated with its larger surface area to volume ratio hindered the interdiffusion of the metals, resulting in an aluminium-depleted martensitic phase surrounded by an aluminium oxide-rich layered structure.
Evolution in microstructure, properties of the laser cladding CoCrFeMoNi coatings at different annealing temperatures
Authors: Liu Ning , Zhou Qichen , Xu Meng , Niu Muye , Zhou Pengjie , Guo Pingyi
Published: June 2023

Laser-cladding CoCrFeMoNi high-entropy alloy coating is composed of face-centred cubic, σ and µ phases. After annealing at 700 °C, many needle-like precipitates of the σ phase are found in the FCC solid solution, and the granular µ phase precipitated at the edge of the primary net-structural σ phase. After annealing at 800 °C, granular µ phases are found inside the primary σ phase. The friction coefficients of the coatings (as-cladded, as-annealed at 700 °C and 800 °C) decrease dramatically compared with the substrate of H13 steel. Obvious spheroidising of the σ phase at 900 °C leads to a decrease of hardness and an increase of friction coefficient. Furthermore, the CoCrFeMoNi high-entropy coatings show better corrosion resistance than H13 steel in 3.5 wt-% NaCl solution.
Architecture of the cortical actomyosin network driving apical constriction in C. elegans
Authors: Zhang Pu , Medwig-Kinney Taylor N. , Goldstein Bob
Published: June 2023

Apical constriction is a cell shape change that drives key morphogenetic events during development, including gastrulation and neural tube formation. The forces driving apical constriction are primarily generated through the contraction of apicolateral and/or medioapical actomyosin networks. In the Drosophila ventral furrow, the medioapical actomyosin network has a sarcomere-like architecture, with radially polarized actin filaments and centrally enriched non-muscle myosin II and myosin activating kinase. To determine if this is a broadly conserved actin architecture driving apical constriction, we examined actomyosin architecture during C. elegans gastrulation, in which two endodermal precursor cells internalize from the surface of the embryo. Quantification of protein localization showed that neither the non-muscle myosin II NMY-2 nor the myosin-activating kinase MRCK-1 is enriched at the center of the apex. Further, visualization of barbed- and pointed-end capping proteins revealed that actin filaments do not exhibit radial polarization at the apex. Our results demonstrate that C. elegans endodermal precursor cells apically constrict using a mixed-polarity actin filament network and with myosin and a myosin activator distributed throughout the network. Taken together with observations made in other organisms, our results demonstrate that diverse actomyosin architectures are used in animal cells to accomplish apical constriction.
Key comparison BIPM.RI(I)-K2 of the air-kerma standards of the BFKH, Hungary, and the BIPM in low-energy x-rays
Authors: Burns D T , Kessler C , Finta V
Published: June 2023

Main text

A key comparison has been made between the air-kerma standards of the BFKH, Hungary, and the BIPM in the low-energy x-ray range. The results show the standards to agree at the level of the expanded uncertainty of the comparison of 6.8 parts in 103. The results are analysed and presented in terms of degrees of equivalence, suitable for entry in the BIPM key comparison database.

To reach the main text of this paper, click on Final Report. Note that this text is that which appears in Appendix B of the BIPM key comparison database https://www.bipm.org/kcdb/.

The final report has been peer-reviewed and approved for publication by the CCRI, according to the provisions of the CIPM Mutual Recognition Arrangement (CIPM MRA).
Addendum: Weyl cocycles, (1986 Class. Quantum Grav.
3 635)
Authors: Bonora L
Published: June 2023

Weyl 0- and 1-cocycles of canonical dimension 6 in six dimensions, which were computed earlier in Bonora et al (1986 Class. Quantum Grav.
3 635), are recalculated from scratch. The analysis yields five Weyl invariants (0-cocycles), instead of four, and the same four non-trivial 1-cocycles (possible trace anomalies), like in that reference (up to the correction of one typo).
Gravastar-like black hole solutions in q-theory
Authors: Selch M , Miller J , Zubkov M A
Published: June 2023

We present a stationary spherically symmetric solution of the Einstein equations, with a source generated by a scalar field ofq-theory. In this theory Riemannian gravity, as described by the Einstein–Hilbert action, is coupled to a three—form field that describes the dynamical vacuum. Formally it behaves like a matter field with its own stress—energy tensor, equivalent to a scalar field minimally coupled to gravity. The asymptotically flat solutions obtained to the field equations represent black holes (BHs). For a sufficiently large horizon radius the energy density is localized within a thin spherical shell situated just outside of the horizon, analogous to a gravastar. The resulting solutions to the field equations, which admit this class of configurations, satisfy existence conditions that stem from the BH no—hair theorem, thanks to the presence of a region in space in which the energy density is negative.
Formation of Ohmic contacts between ferromagnetic Cr2Ge2Te6 and two-dimensional metals
Authors: Kang Wei , Wang Jintian , Wang Wei , Wang Yan , Wang Lin , Liu Xiaoqing , Ye Ziqin , Liu Jun , Fang Liang , Zhou Miao
Published: June 2023

As a ferromagnetic semiconductor, two-dimensional (2D) Cr2Ge2Te6 holds significant implications for electronic and spintronic devices. To achieve 2D electronics, it is essential to integrate Cr2Ge2Te6 with 2D electrodes to form Schottky-barrier-free Ohmic contacts with enhanced carrier injection efficiency. Herein, by using first-principles calculations based on density-functional theory, we systematically investigate the structural, energetic, electronic and magnetic properties of 2D heterojunctions by combining Cr2Ge2Te6 with a series of 2D metals, including graphene, ZrCl, NbS2, TaS2, TaSe2, Zn3C2, Hg3C2, and Zr2N. Results show that NbS2, TaS2, TaSe2, Zn3C2, Hg3C2, and Zr2N form Ohmic contacts with Cr2Ge2Te6, in contrast to graphene and ZrCl that exhibit a finite Schottky barrier. By examining the tunneling barriers and Fermi level shift, we reveal that the heterojunctions with Zn3C2 and Hg3C2 as electrodes exhibit advantages of both high electron injection efficiency and spin injection efficiency, for which an apparent decrease of the magnetic moment of Cr atoms in Cr2Ge2Te6 can be observed. These findings not only provide physical insights into the role of interfacial interaction in regulating the physical properties of 2D heterojunctions, but also pave way for the development of high-performance spintronic nanodevices for practical implementation.
High-precision radius and sphericity measurement for microspheres of micro-CMM probe tip
Authors: Zhao Wenkai , Li Rui-Jun , Duan Liuhui , Cheng Zhenying , Pan Qiaosheng , Huang Qiangxian , Fan Kuang-Chao
Published: June 2023

The microsphere profile of probe tips has to be measured and compensated to improve the measurement accuracy of micro-coordinate measuring machines (micro-CMMs) to less than several hundred nanometers. A high-precision radius and sphericity measurement method for the microsphere of the CMM probe tip is proposed in this article. Different circumferences of the tested microsphere are measured, and the true radius of any measuring point on the surface can be obtained after separating the runout errors. Then the sphericity of the tested microsphere can be evaluated by the minimum zone sphere method. A corresponding measuring system is developed based on the analysis of the primary error model and mechanical model, and verification experiments are conducted using a ruby microsphere (A-5000-7801, Renishaw Corporation) as the reference, whose claimed diameter and sphericity are 700 µm and 130 nm, respectively. Six groups of repeated experiments are performed, and 18 000 measurement points on 15 circumferences are recorded in each group of experiments. Results show that the average radius of the tested microsphere is 350.003 µm, and the average sphericity error is 208 nm with a standard deviation of 5.3 nm. Finally, the expanded uncertainty of the measurement results of the developed system is calculated as 209 nm (k = 1.96, normal distribution). The proposed method and system can be used in the precision measurements and compensations for probe tips of micro-CMMs and other parts, such as microspheres used in micro-bearings and micro-manufacturing machines.
Synergistic effect of multi-element co-segregation on mechanical properties of Mg
101ˉ2
twin grain boundary
Authors: Lin Jiarui , Han Hui , Tian Yanzhong , Pang Xueyong , Qin Gaowu
Published: June 2023

Properties of grain boundaries (GBs) are pronouncedly influenced by alien elemental segregation. Synergistic effect of co-segregation behavior on mechanical properties of Mg

10

1
ˉ

2

twin GB was systematically investigated with first-principles calculations. Ten elements (Ni, Mn, Zn, Al, Ag, Ti, Li, Zr, Y, Ca) for single segregation and four solute combinations (Al–Ca, Al–Y, Zn–Ca, Zn–Y) for co-segregation were chosen respectively, the segregation energies and solubility energies with different elemental concentrations were calculated to evaluate the thermodynamic stability of corresponding segregated GBs. These solute atoms have unique effects on the stability of the system, and the interaction between solute atoms also has a synergistic effect on the stability of the system. It is found that the segregation tendency is enhanced and the GB structure tends to be stable with the increase of the concentration of solute atoms at the appropriate sites, regardless of single-element segregation or co-segregation. The redistribution of GB charges due to co-segregation significantly affects the binding and mechanical properties of GBs. With the increase of the co-segregation concentration, the lamellar charge is transferred between the matrix and the twins, which further enhances the electron hybridization and leads to a notable enhancement of interface binding. This shows that the appropriate combination of solute elements can effectively improve the mechanical properties of the interface. The manuscript reveals the theoretical understanding of the effect of elemental segregation on the mechanical properties of GB, and provides design ideas for the tuning of mechanical properties of magnesium alloy by GB engineering.
Dielectric metasurfaces for next-generation optical biosensing: a comparison with plasmonic sensing
Authors: Chung Taerin , Wang Hao , Cai Haogang
Published: June 2023

In the past decades, nanophotonic biosensors have been extended from the extensively studied plasmonic platforms to dielectric metasurfaces. Instead of plasmonic resonance, dielectric metasurfaces are based on Mie resonance, and provide comparable sensitivity with superior resonance bandwidth, Q factor, and figure-of-merit. Although the plasmonic photothermal effect is beneficial in many biomedical applications, it is a fundamental limitation for biosensing. Dielectric metasurfaces solve the ohmic loss and heating problems, providing better repeatability, stability, and biocompatibility. We review the high-Q resonances based on various physical phenomena tailored by meta-atom geometric designs, and compare dielectric and plasmonic metasurfaces in refractometric, surface-enhanced, and chiral sensing for various biomedical and diagnostic applications. Departing from conventional spectral shift measurement using spectrometers, imaging-based and spectrometer-less biosensing are highlighted, including single-wavelength refractometric barcoding, surface-enhanced molecular fingerprinting, and integrated visual reporting. These unique modalities enabled by dielectric metasurfaces point to two important research directions. On the one hand, hyperspectral imaging provides massive information for smart data processing, which not only achieve better biomolecular sensing performance than conventional ensemble averaging, but also enable real-time monitoring of cellular or microbial behaviour in physiological conditions. On the other hand, a single metasurface can integrate both functions of sensing and optical output engineering, using single-wavelength or broadband light sources, which provides simple, fast, compact, and cost-effective solutions. Finally, we provide perspectives in future development on metasurface nanofabrication, functionalization, material, configuration, and integration, towards next-generation optical biosensing for ultra-sensitive, portable/wearable, lab-on-a-chip, point-of-care, multiplexed, and scalable applications.
Unsupervised deep learning-based displacement estimation for vascular elasticity imaging applications
Authors: Karageorgos Grigorios M , Liang Pengcheng , Mobadersany Nima , Gami Parth , Konofagou Elisa E
Published: June 2023

Objective. Arterial wall stiffness can provide valuable information on the proper function of the cardiovascular system. Ultrasound elasticity imaging techniques have shown great promise as a low-cost and non-invasive tool to enable localized maps of arterial wall stiffness. Such techniques rely upon motion detection algorithms that provide arterial wall displacement estimation. Approach. In this study, we propose an unsupervised deep learning-based approach, originally proposed for image registration, in order to enable improved quality arterial wall displacement estimation at high temporal and spatial resolutions. The performance of the proposed network was assessed through phantom experiments, where various models were trained by using ultrasound RF signals, or B-mode images, as well as different loss functions. Main results. Using the mean square error (MSE) for the training process provided the highest signal-to-noise ratio when training on the B-modes images (30.36 ± 1.14 dB) and highest contrast-to-noise ratio when training on the RF signals (32.84 ± 1.89 dB). In addition, training the model on RF signals demonstrated the capability of providing accurate localized pulse wave velocity (PWV) maps, with a mean relative error (MREPWV) of 3.32 ± 1.80% and an R2 of 0.97 ± 0.03. Finally, the developed model was tested in human common carotid arteries in vivo, providing accurate tracking of the distension pulse wave propagation, with an MREPWV = 3.86 ± 2.69% and R2 = 0.95 ± 0.03. Significance. In conclusion, a novel displacement estimation approach was presented, showing promise in improving vascular elasticity imaging techniques.
Recombination of oxygen atoms on the surface of oxidized polycrystalline nickel—temperature and pressure dependences
Authors: Paul Domen , Mozetič Miran , Zaplotnik Rok , Ekar Jernej , Vesel Alenka , Primc Gregor , Đonlagič Denis
Published: June 2023

The recombination of neutral oxygen atoms in the ground state on the oxidized nickel samples was studied experimentally in the range of pressures where the maximum density occurs in weakly ionized low-pressure oxygen plasma, i.e. between 40 and 200 Pa. The recombination coefficient was determined in the flowing afterglow. The source of oxygen atoms was plasma sustained in a quartz tube of inner diameter 4.7 mm by a microwave discharge in the surfatron mode. The recombination coefficient was determined in the afterglow chamber, which was a Pyrex tube with an inner diameter of 36 mm. The density of oxygen atoms in the afterglow chamber was varied by adjusting the discharge power, the gas flow, the pressure, and the position of a recombinator. Such flexibility of the experimental system enabled adjustment of the temperature of the oxidized nickel samples independently from the O-atom density in its vicinity or other parameters. The density of oxygen atoms in the afterglow chamber at various system parameters was determined by the Šorli method, which is reliable, and has an accuracy of about 20%. The recombination coefficient was determined by calorimetry. The coefficient was inversely proportional to the square root of the pressure and exponentially to the sample temperature. Systematic measurements performed at various pressures and temperatures enabled empirical formula, which were explained qualitatively by recombination kinetics.
The surface tension of Ga2O3 melt measured by a drop-weight method in an optical floating-zone furnace
Authors: Wu Dan , Li Cheng , Ma Keke , Wang Jiabin , Xia Ning , Yan Yuchao , Jin Zhu , Zhang Hui , Yang Deren
Published: June 2023

The surface tension of Ga2O3 melt is successfully measured using a drop-weight method in an optical floating-zone furnace that we have developed. The method is verified to be feasible by measuring the surface tension value of TiO2 melt and then comparing it with values in previous reports determined by other methods. We find that the surface tension of Si-doped Ga2O3 melt increases with the decrease in the Si doping concentration and reaches 527.9 mN m−1 for pure Ga2O3 melt. The surface tension of the unintentionally doped Ga2O3 melt is also measured to be 519.3 mN m−1 in the presence of some common contaminants appearing in Czochralski and edge-defined film-fed growth methods, including Ir, Al, and Si.
Development and validation of a probabilistic multistage algorithm for damage localization in piezo-monitored structures
Authors: De Luca Alessandro , Perfetto Donato , Polverino Antonio , Minardo Aldo , Caputo Francesco
Published: June 2023

All structures during operating life can be affected by faults induced by accidental events and operational conditions. Structural health monitoring systems can provide quasi-real-time diagnosis of the structure, thus enabling the condition-based maintenance approach. By means of piezoelectric transducers (PZTs) and ultrasonic guided waves (UGW), the structural integrity can be easily interrogated, even though laborious post-processing techniques are required to correctly interpret sensed data. This work aims to devise a new automatic diagnosis framework based on the propagation of UGW for thin-walled structures fault detection and localisation. Specifically, a fully automated damage identification algorithm was developed through a numerical dataset obtained by finite element simulations, and then validated experimentally. The case of study consisted of a square-shaped aluminium plate equipped with a five PZTs network. Five different damage positions and three different damage sizes were considered. The originality of the proposed algorithm lies in the data processing methodology as well as in its capability to detect damages located inside and outside the sensors network, even close to the panel edges. Algorithm provides, in less than 15 s, indications on the possible damage location and related probability position with a reduced dispersion with respect to other algorithms proposed in literature. A clear image is created displaying the damage position map. The visualisation of the damage position map on the surface of the monitored part allows successful damage imaging and would enable operators to address more efficiently the inspection procedures only in the highlighted areas, reducing maintenance and repair expenses.
What it could feel like to press on an auxetic: effect of Poisson’s ratio on the indenter
Authors: Attard Daphne , Gatt Ruben , Caruana-Gauci Roberto , Grima-Cornish James N , Cauchi Reuben , Sillato Darren , Cerasola Dario , Ficarra Giovanni , Bezzina Daniel S , Formosa Cynthia , Gatt Alfred , Grima Joseph N
Published: June 2023

The behaviour of an indenter having a hard inner core and a softer outer shell, meant to emulate a human finger, pressing upon a sample covered with an isotropic negative/zero/positive Poisson’s top protective layer was investigated through static finite-element simulations. It was shown that if the material being indented had a comparable Young’s modulus to the outer shell of the indenter, a very negative Poisson’s ratio (NPR) results in more pronounced deformations and stresses within the indenter due to the auxetic material offering a higher resistance to indentation. Pressing of an auxetic material with Poisson’s ratio of −0.90 having the same Young’s modulus as that of the softer outer core of the indenter (1 MPa), was found to result in stresses in the indenter which were approximately double to those measured when pressing a conventional material with same Young’s modulus having Poisson’s ratio +0.45. This indicates that auxetics with a very high NPR may feel more uncomfortable when pressed with a finger compared to materials of the same Young’s modulus having a conventional positive Poisson’s ratio (PPR). However, it was also shown that in such scenarios, the auxetic protective layer being indented could be made much thinner whilst still retaining the same functionality. In fact, the simulations suggest that a conventional material with Poisson’s ratio +0.45 indents more than five times as much as an auxetic material with Poisson’s ratio of −0.90 having the same Young’s modulus of 1 MPa. It was also shown that in situations where the material being indented had a much higher Young’s modulus to that of the indenter, the deformations and stresses within the indenter are practically identical irrespective of the Poisson’s ratio, i.e. a human finger is unlikely to be able to perceive the difference between an auxetic and a conventional PPR material.
Low frequency sound insulation performance of membrane-type acoustic metamaterial with eccentric mass block
Authors: Cai Tong , Huang Shuang , Guo Hui , Sun Pei , Yuan Tao
Published: June 2023

To improve the sound insulation performance in the low frequency band of membrane-type acoustic metamaterial (MAM), membrane-type acoustic metamaterial with eccentric mass block (MAMEM) is used as the object in this paper. The influence of composite mass block on the low frequency sound insulation performance of MAMEM is also studied. Firstly, a mathematical model of sound insulation based on MAMEM was conducted. Secondly, the elastic layer is introduced into the mass block of the MAMEM to form a membrane-type acoustic metamaterial with eccentric composite mass block (MAMECM) structure. The study shows that the peak sound insulation frequency of the structure is obtained with a left shift of 70 Hz, and the introduction of the elastic layer will be beneficial to realize the low frequency regulation of the structural band gap. Thirdly, the influence of the thickness of the elastic and metal layers on the sound insulation of the MAMECM was discussed. The study shows that when the thickness of the metal layer is 1 mm and the thickness of the elastic layer is 10.7 mm, the peak sound insulation reaches 70 dB at this frequency. The peak frequency of sound insulation can reach 260 Hz, which is 140 Hz lower than the MAM at the same mass. Moreover, under the premise that the total mass of composite material blocks remains unchanged, the sound insulation peak frequency of sound transmission loss (STL) curve will shift to the left when the thickness of metal layer is smaller, and the sound insulation at the peak frequency is larger. Finally, the accuracy of the results is verified by experiments.
Large dynamic range terahertz phase modulator based on graphene-metal hybrid metasurface
Authors: Wang Hong , Hu Fangrong , Xu Xinlong , Gong Yumin , Jiang Mingzhu , Zhang Longhui , Zou Yingchang
Published: June 2023

Terahertz (THz) dynamic phase modulator is indispensable in THz wireless communications, high-resolution imaging and radar systems. However, up to now, it is difficult to achieve dynamic tunable phase shift of more than 150 degrees in single-layer transmission mode. In this work, we proposed a THz dynamic large phase modulator based on graphene-metal hybrid metasurface. The simulation results show that, when the Fermi level of graphene changes from 0 eV to 0.86 eV, the phase shift exceeds 176 degrees. By modifying the structural parameters, a phase shift of 170 degrees can be achieved in a bandwidth of 50 GHz. We investigated the physical mechanism of the dynamic phase modulator, and established the relationship between phase shift and Fermi level theoretically. This study paves a new way for realizing dynamic large phase modulation, which is very important for the THz broadband wireless communication, high-resolution imaging and radar system.
Negative differential resistance in Si nanostructure: role of interface traps
Authors: Chakrabarty Sudipta , Hossain Syed Minhaz
Published: June 2023

Negative differential resistance (NDR) has been observed in I-V characteristics measured between two aluminum (Al) pads deposited on a layer containing Silicon nanostructures. This feature has been observed for suitable bias range and specific direction of voltage sweep. NDR has been found to show up within a specific range of lower and upper threshold voltages for each of the samples studied in this work. The amount of NDR has been found to depend on voltage scan rate and bias range. The observed phenomena have been explained using the dynamics of charge trapping and detrapping at the surface/interface defect states present at the boundary of the nanostructured silicon and the oxide layer. An equivalent circuit designed by incorporation of suitable resistance and capacitance representing the trap assisted charge transport within the aluminum-Silicon nanostructure junctions has produced similar I-V characteristics as obtained in the experimental results. Repeatability of NDR shows the potential of the device to be used in oscillators.
Research on damage characteristics and microscopic appearance of ReBCO tapes after DC overcurrent
Authors: Yang Zili , Xu Ying , Li Xianhao , Yang Zhixing , Zhang Zitong , Ding Xuan , Zhou Difan , Peng Shuhao
Published: June 2023

With the expansion of the power grid, the use of DC transmission technology is becoming increasingly prevalent. This has led to higher transmission voltage levels, which in turn have brought to the fore the issue of large short-circuit currents. The existing circuit limiter’s performance is insufficient to meet the growing demand. Superconducting fault current limiter, which based on ReBCO tapes, is considered to be the solution to the problem of large short-circuit current. However, the failure mode of ReBCO tapes under DC overcurrent remains to be studied. In the superconducting state, the current flows mainly through the superconducting layer. Therefore, it is necessary to investigate the overcurrent characteristics of the superconducting layer after overcurrent. In this work, the damage characteristics and microscopic appearance of ReBCO tapes after overcurrent were investigated. The magnetic field distribution characteristics and the microscopic appearance of the superconducting layers of ReBCO tapes with different degrees of critical current recession were investigated, and the chemical elements of the superconducting layers were analyzed. The results show that large-area pits were found on superconducting layer after overcurrent, the element types and mass proportions did not change. Overcurrent affects the superconductivity of the tape mainly by changing the physical structure of the superconducting layer.
Single-step detection of toxic airborne metallic nanoparticles using Goos–Hänchen effect in photonic Bragg grating structures
Authors: Ghasemi Fatemeh , Adinehpour Sara , Razi Sepehr
Published: June 2023

A real-time photonic crystal sensor is suggested for the detection of airborne heavy metal nanoparticles (HMNPs). The sensor consists of a sandwiched sampling cell between two stacks of alternating TiO2 and Si-Ge layers, forming the core of the device. The sensor’s performance is based on monitoring changes in both the intensity and phase of a probe beam as it propagates through the core. By analyzing the fluctuations in intensity, central frequency, and full width at half maximum (FWHM) of the resonant mode within the transmittance spectrum bandgap, or by monitoring the phase changes at the angle of maximum transmittance that may result in a remarkable Goos–Hänchen (GH) shift in transmittance, the sensor can identify the pollutant nanoparticles. Tuning the thicknesses of the slabs and the number of unit cells in the photonic crystal can dynamically shift the resonant mode and bandgap edges, allowing for easy adjustment of the sensor’s responsivity. Furthermore, the optical response of the sensor can be tuned through external parameters such as the incident angle of the probe light or an externally applied electric field. Additionally, the sensor exhibits sensitivity not only to changes in the extent of the sample but also to the shape of the present HMNPs. These characteristics make the proposed configuration cost-effective, user-friendly, and suitable for HMNPs detection without the need for complex sample preparation, data analyses or additional tools/accessories.
Predictive uncertainty on astrophysics recovery from multifield cosmology
Authors: Andrianomena Sambatra , Hassan Sultan
Published: June 2023

We investigate how the constraints on the density parameter (Ωm), the power spectrum amplitude (σ
8) and the supernova feedback parameters (A
SN1 and A
SN2) vary when exploiting information from multiple fields in cosmology. We make use of a convolutional neural network to retrieve the salient features from different combinations of field maps from IllustrisTNG in the CAMELS project. The fields considered are neutral hydrogen (HI), gas density (Mgas), magnetic fields (B) and gas metallicity (Z). We estimate the predictive uncertainty — sum of the squares of aleatoric and epistemic uncertainties — of the parameters inferred by our model by using Monte Carlo dropout, a Bayesian approximation. Results show that in general, the performance of the model improves as the number of channels of its input is increased. In the best setup which includes all fields (four channel input, Mgas-HI-B-Z) the model achieves R
2 > 0.96 on all parameters. Similarly, we find that the predictive uncertainty, which is dominated by the aleatoric uncertainty, decreases as more fields are used to train the model in general. The uncertainties obtained by dropout variational inference are overestimated on all parameters in our case, in that the predictive uncertainty is much larger than the actual squared error, which is the square of the difference between the ground truth and prediction. After calibration, which consists of a simple σ scaling method, the average deviation of the predictive uncertainty from the actual error goes down to 25% at most (on A
SN1).
Infiltration of tumor spheroids by activated immune cells
Authors: Mukherjee Mrinmoy , Chepizhko Oleksandr , Chiara Lionetti Maria , Zapperi Stefano , La Porta Caterina A M , Levine Herbert
Published: June 2023

Recent years have seen a tremendous growth of interest in understanding the role that the adaptive immune system could play in interdicting tumor progression. In this context, it has been shown that the density of adaptive immune cells inside a solid tumor serves as a favorable prognostic marker across different types of cancer. The exact mechanisms underlying the degree of immune cell infiltration is largely unknown. Here, we quantify the temporal dynamics of the density profile of activated immune cells around a solid tumor spheroid. We propose a computational model incorporating immune cells with active, persistent movement and a proliferation rate that depends on the presence of cancer cells, and show that the model able to reproduce semi-quantitatively the experimentally measured infiltration profile. Studying the density distribution of immune cells inside a solid tumor can help us better understand immune trafficking in the tumor micro-environment, hopefully leading towards novel immunotherapeutic strategies.
Polarized laser speckle images produced by calibrated polystyrene microspheres suspensions: comparison between backscattering and transmission experimental configurations
Authors: Loutfi Hadi , Pellen Fabrice , Le Jeune Bernard , Le Brun Guy , Abboud Marie
Published: June 2023

In this paper, we analyze polarized laser speckle images produced by calibrated polystyrene microspheres suspensions and discuss the results obtained while considering two different experimental configurations for light detection: speckle-transmission setup and speckle-backscattering one. The degree of light polarization (DOP) and speckle grain size (dx) were monitored in both cases. Results show that, when backscattered photons are detected, the degree of circular polarization allows a fine monitoring of the variation of scatterers concentration in a sample. A helicity flipping is detected as the scatterers concentration increases, showing that a transition from a simple scattering regime to a multiple scattering one is taking place. When transmitted scattered photons are detected dx is a better parameter than DOP for following changes in scattering regime: dx values initially increase slightly then decrease as the scattering coefficient increases. The observed maximum corresponds to the shift from a simple to a multiple scattering regime.
Compact entanglement concentration for three-electron-spin W states with error-detected parity-check gates
Authors: Fan Gang , Ren Xue-Mei , Fang-Fang Du
Published: June 2023

We present a compact entanglement concentration protocol (ECP) for unknown less-entangled three-electron-spin W states, resorting to the interaction rules between the circularly polarized photon and cavity-quantum-dot (QD) system. In the first step of our ECP, the parties utilize two less-entangled three-electron-spin systems not only to obtain one partially entangled three-electron-spin system with two unknown parameters if the odd-parity occurs with the parity-check gate (PCG) but also to get one entangled two-electron-spin system if the even-parity occurs. By exploiting the above three-electron-spin and two-electron-spin systems as the resource for the second step of our ECP, the parties can obtain a standard three-electron-spin W state if the odd parity occurs. Meanwhile, the systems in the even-parity instance can be used as the resource in the next round of our ECP. As the imperfect performances originated from the side leakage and the limited coupling strength of the cavity-QD system can be reflected by clicking the single-photon detectors, the fidelity of the PCG is unit, in principle, immune to strong coupling-strength restriction. Moreover, the success of our ECP not only is heralded by the detectors but also its efficiency further is improved by repeating the operation processes. Therefore, our ECP is useful in the quantum communication network.
Intelligent machine plus production line digital twin model construction technology
Authors: Ke Guo , Dashun Zhang , Liqin Miao , Jing Wang , Juan Du , Shubo Li , Huan Qiao , Lizhong Sun
Published: June 2023

Digital twin is one of the key technology of intelligent digital manufacturing field, the related research is still in the initial stage This article in complex parts machining production line as the research object, from the geometric physical behavior rules four aspects to explore the digital twin modeling technology of production line Through the geometric model and the size of the physical model visualization expression line shape Based on the three-layer model of geometric physical behavior, the digital twin behavior model is constructed to describe the operation failure rule of the machine and unit. Driven by real-time information collection and fusion technology, closed-loop control and iterative optimization are realized Finally, the application value of digital twin technology in intelligent monitoring information feedback decision control is demonstrated through the intelligent control system of machining production line.
A backlash identification and compensation method for high-speed aircraft angular rate control
Authors: Lyu Huitao , Zhang Yi , Gong Zheng , Chen Yongliang
Published: June 2023

This paper focus on the hysteresis phenomenon of the roll angular rate control resulting from the backlash of the actuators for a high-speed aircraft in real flight. First, the backlash is analyzed in the time and frequency domain, and then the backlash parameters are identified using the statistic method. Second, based on the inverse backlash model, the L
1 adaptive controller with the backlash compensation is designed. Third, two simulation tests with and without the backlash compensation are conducted and the simulation results are compared which show the effectiveness of the backlash-compensation-based controller.
The impact analysis of the un-commanded brake caused by pedal jamming on the aircraft
Authors: Jian Li
Published: June 2023

The rudder brake pedal unit is an important part of aircraft flight control system, also is the human machine interface for pilots to control the aircraft rudder and brake. By applying forces at different positions and directions on the pedals, the pilot can realize the rudder control and brake control functions respectively. This paper takes the rudder brake pedal control unit of civil aircraft as the research object. The research process is as follows. Firstly, an analysis about the influence on the compression of brake sensor by operating pedal when the brake pedal jamming is carried out using CATIA. Secondly, the forces acted on aircraft during rolling on the ground are analyzed and the ground dynamic equations are presented. Finally, through the simulation on the engineering simulator of a certain aircraft, the influence of differential brake caused by brake pedal jamming on the aircraft speed after V1 (take-off decision speed) in the take-off phase is verified. The research results of this study show that, the impact of un-commanded differential brake caused by rudder brake pedal jamming on the safety of the aircraft must be considered during the aircraft design process, and effective measures must be taken to avoid the occurrence of un-commanded deceleration after V1 in the take-off phase.
Research on multi-UAV hierarchical task allocation in large-scale scenarios
Authors: Wang Qiang , Han Xingye , He Weizhen , Cheng Yongsheng
Published: June 2023

The task allocation problem of multiple UAVs in large-scale scenarios has the characteristics of large amount of computation, poor real-time performance, non-convergence or slow convergence. Therefore, this paper designs a hierarchical task allocation method to solve the task allocation problem when multiple UAVs perform large-scale tasks. The problem is divided into two sub-problems, task clustering and task ranking, by using a hierarchical structure, which effectively reduces the scale of solution. The high-level task clustering is used to determine which UAV performs which tasks, and the clustering algorithm based on auction criteria is used to perform task clustering; the bottom-level task sorting is used to obtain the best task execution sequence for the UAV to perform its corresponding tasks. The ant colony algorithm(ACO) is used to sort tasks. The simulation results show that the proposed algorithm can effectively solve the multi-UAV large-scale task allocation problem, and has good realtime performance and convergence.