bluuebunny/crossref_metadata_2025_split huggingface dataset:
Three-dimensional modelling of a self-sustained atmospheric pressure glow discharge
Authors: Boutrouche Valentin , Trelles Juan Pablo 
Published: September 2022

Abstract
The atmospheric pressure glow discharge (APGD) is a relatively simple and versatile plasma source used in diverse applications. Stable APGD operation at high currents, generally a challenge due to instabilities leading to glow-to-arc transition, has been demonstrated using actively-controlled cathodic cooling. This article presents the computational modelling and simulation of a self-sustained direct-current APGD in helium within a 10 mm pin-to-plate inter-electrode gap for currents ranging from 4 to 40 mA. The APGD model is comprised of the conservation equations for total mass, chemical species, momentum, thermal energy of heavy-species and of free electrons, and electric charge. The model equations are discretized using a nonlinear variational multi-scale finite element method that has demonstrated superior accuracy in other plasma flow problems, on a temporal and three-dimensional computational domain suitable to unveil the potential occurrence of instabilities. Modelling results show good agreement with experimental measurements of voltage drop and the same trend but higher values of temperature. The higher temperatures obtained by the simulations appear to be due to the absence of a near-cathode heat dissipation model. The results also reveal that the distribution of electron density and of the ratio of atomic helium ions to total ions transitions from monotonically increasing away from the cathode to presenting a minimum near the centre of the gap with increasing current.
Theoretical investigation of lattice-matched III-N-V/Si double-junction solar cells
Authors: Zhang Xiaobin , Liu Liming , Chi Feng , Wang Ke , Lin Kaiwen , Wang Yuehui 
Published: September 2022

Abstract
The lattice-matched III-N-V/Si double-junction (DJ) solar cells are designed with GaNAsP and GaInNP top cells, respectively. Under AM1.5G condition, the efficiencies of III-N-V/Si DJ cells are calculated with variable electron lifetime (τe
) and electron surface recombination velocity (Se
) in top cell. When Se
is 100 cm s−1 and τe
rises from 1 to 1000 ns, the optimal efficiency of GaNAsP/Si cell increases from 31.12% to 36.13% due to the increasing short-circuit current and open-circuit voltage. With τe
of 100 ns, the optimal efficiency keeps at a high value of ∼35% when Se
changes from 10 to 1000 cm s−1, but drops obviously with Se
of 10 000 cm s−1. In comparison, the optimal efficiency of GaNAsP/Si cell is less sensitive to Se
than to τe
. With fixed Se
of 100 cm s−1, GaNAsP/Si cell shifts the optimal top-cell bandgap from 1.716 to 1.787 eV when raising τe
from 1 to 1000 ns. However, the effect of Se
on optimal top-cell bandgap is negligible. For III-N-V/Si cell with 100 ns τe
and 100 cm s−1
Se
, an optimal efficiency is obtained as ∼35.1%, which would be closer to the experimental limit owing to the expectable values of τe
and Se
. Furthermore, the optimal efficiency of GaNAsP/Si cell drops slightly when thinning Si substrate from 300 to 150 μm, but has a maximum of 35.95% with substrate doping of 1 × 1016 cm−3 when the doping concentration varies from 1 × 1015 to 1 × 1018 cm−3. The results and discussion in this work may act as a guidance for studying III-N-V/Si DJ cell.
A low-cost digital coding metasurface applying modified ‘crusades-like’ cell topologies for broadband RCS reduction
Authors: Wang Chao , Wang Ru-Zhi , An Ze-Lin , Liu Li-Ying , Zhou Yun-Sheng , Tang Zhi-Xiang , Wang Wei-Dong , Zhang Sheng-Jun 
Published: September 2022

Abstract
The popularity of metasurfaces (MSs) has been continuously grown due to their powerful ability to manipulate electromagnetic waves. One of their important application areas is radar stealth technology, in particular, the realization of radar cross section (RCS) reduction. However, the high costs of substrate material limit its large-scale applications. In this paper, a binary digital coding metasurface (DCM) with novel modified ‘crusades-like’ cell topologies is proposed and implemented using a low-cost FR4 substrate to achieve broadband RCS reduction (RCSR). To realize the 1-bit DCM, initially, two elements with rotational symmetry are chosen for polarization insensitive properties while considering an unconventional phase deviation criteria. Next, the optimal hybrid coding layout is given out by using a genetic algorithm and antenna array theory. Last, the proposed novel MS prototype composed of 40 × 40 unit cells is fabricated and measured to validate the RCSR behaviour predicted by full-wave simulation. The results show a good consistency between the theoretical simulation and experimental measurement from 7.9 to 15.8 GHz. In addition, the simulation results indicate that the designed MS features high angular stability. Our work may provide a promising approach and good reference for the low-cost MS design in radar stealth applications.
Design of experiments: a statistical tool for PIV uncertainty quantification
Authors: Adatrao Sagar , van der Velden Simone , van der Meulen Mark-Jan , Bordes Marc Cruellas , Sciacchitano Andrea 
Published: September 2022

Abstract
A statistical tool called design of experiments (DOEs) is introduced for uncertainty quantification in particle image velocimetry (PIV). DOE allows to quantify the total uncertainty as well as the systematic uncertainties arising from various experimental factors. The approach is based on measuring a quantity (e.g. time-averaged velocity or Reynolds stresses) several times by varying the levels of the experimental factors which are known to affect the value of the measured quantity. Then, using Analysis of Variances, the total variance in the measured quantity is computed and hence the total uncertainty. Moreover, the analysis provides the individual variances for each of the experimental factors, leading to the estimation of the systematic uncertainties from each factor and their contributions to the total uncertainty. The methodology is assessed for planar PIV measurements of the flow over a NACA0012 airfoil at 15 degrees angle of attack considering five experimental factors, namely camera aperture, inter-frame time separation, interrogation window size, laser sheet thickness and seeding density. Additionally, the methodology is applied to the investigation by stereoscopic PIV of the flow at the outlet of a ducted Boundary Layer Ingesting propulsor. The total uncertainty in the time-averaged velocity as well as the constituent systematic uncertainties due to the experimental factors, namely camera aperture, inter-frame time separation, interrogation window size and stereoscopic camera angle, are quantified.
A novel unbalanced weighted KNN based on SVM method for pipeline defect detection using eddy current measurements
Authors: Lu Senxiang , Yue Yiqiao , Liu Xiaoyuan , Wu Jing , Wang Yongqiang 
Published: September 2022

Abstract
Pipeline safety inspections are particularly important because they are the most common means of energy transportation. In order to avoid pipe leakage, eddy current inspection is often used in metal pipe defect detection. However, in practice, due to problems such as noise and interference, a small number of labeled pipeline defect samples, and unbalanced sample distribution, the detection task cannot be completed. To address the above problems, this study proposes an unbalanced weighted k-nearest neighbor (KNN) based on support vector machine (SVM) defect detection algorithm. The multi-segment hybrid adaptive filtering algorithm is adopted to improve the identification of strong interference and large noise eddy current signals in this paper while retaining useful information such as defects. At the same time, the unbalanced weighted KNN based on the SVM defect detection algorithm is used to solve the problems of low accuracy and large limitations of the algorithm. The experimental results show that, compared with the KNN and SVM algorithms, the detection rate, false detection rate, and missed detection rate of defects are significantly improved.
Optical properties of black silicon structures ALD-coated with Al2O3
Authors: Schmelz David , Gerold Kristin , Käsebier Thomas , Sergeev Natali , Szeghalmi Adriana , Zeitner Uwe D 
Published: September 2022

Abstract
Atomic layer deposited (ALD) Al2O3 coatings were applied on black silicon (b-Si) structures. The coated nanostructures were investigated regarding their reflective and transmissive behaviour. For a systematic study of the influence of the Al2O3 coating, ALD coatings with a varying layer thickness were deposited on three b-Si structures with different morphologies. With a scanning electron microscope the morphological evolution of the coating process on the structures was examined. The optical characteristics of the different structures were investigated by spectral transmission and reflection measurements. The usability of the structures for highly efficient absorbers and antireflection (AR) functionalities in the different spectral regions is discussed.
Micro-mechanisms of failure in nano-structured maraging steels characterised through in situ mechanical tests
Authors: Jacob Kevin , Sahasrabuddhe Hrushikesh , Hohenwarter Anton , Dixit Saurabh , Jaya Balila Nagamani 
Published: September 2022

Abstract
High-pressure-torsion (HPT) processing introduces a large density of dislocations that form sub-grain boundaries within the refined nano-scale structure, leading to changes in precipitate morphology compared to hot-rolled maraging steels. The impact of such nanostructuring on the deformation and fracture micro-mechanisms is being reported for the first time using in situ characterization techniques along with transmission electron microscopy and atom probe tomography analysis, in this study. Digital image correlation has been used to quantify the full field strain maps in regions of severe strain localization as well as to determine the fracture toughness through critical crack tip opening displacements. It is seen that the phenomenon of planar slip leads to strain softening under uniaxial deformation and to crack branching under a triaxial stress state in hot rolled maraging steels. On the other hand, nano-structuring after HPT processing creates a large number of high angle grain boundaries as dislocation barriers, leading to strain hardening under uniaxial tension and nearly straight crack path with catastrophic fracture under triaxial stress state. Upon overaging, the hot-rolled sample shows signature of transformation induced plasticity under uniaxial tension, which is absent in the HPT processed overaged samples, owing to the finer reverted austenite grains containing higher Ni concentration in the latter. In the overaged fracture test samples of both the hot-rolled and HPT conditions, crack tips show a signature of strain induced transformation of the reverted austenite to martensite, due to the accompanying severe strain gradients. This leads to a higher fracture toughness even while achieving high strengths in the overaged conditions of the nanocrystalline HPT overaged samples. The results presented here will aid in design of suitable heat treatment or microstructure engineering of interface dominated nano-scale maraging steels with improved damage tolerance.
Buckling behavior of ternary one-dimensional van der Waals heterostructures
Authors: Gao Bingjie , Lin Shu , Wan Jing , Cai Haifang , Zhu Zuoquan 
Published: September 2022

Abstract
One-dimensional van der Waals heterostructures (1D vdWHs) may suffer from external compression when applied in field-effect, light-emitting and photovoltaic devices. Ternary 1D vdWHs were recently reported to be successfully synthesized (Xiang et al 2020 Science
367, 537). In present work, the buckling behavior of ternary 1D vdWH consisting of an inner carbon nanotube, a middle boron nitride nanotube and an outer molybdenum disulfide nanotube is extensively investigated by using molecular dynamics simulations. We find that the composite can effectively enhance the capability of axial compression of the inner nanotubes. The 1D vdWH gradually loses its stability under uniaxial compression and the critical stress of buckling decreases as the temperature increases. Slenderness ratio α of 4.8 ≤ α ≤ 7.2 has a slight influence on the strength and stability of ternary 1D vdWH under axial compression. To obtain a 1D vdWH with best compressive stability and strength, there is an optimal diameter existing for any specific length. Our work provides guidance for the design of 1D vdWH with desired compressive stability.
Dynamically defined subsets of generic self-affine sets*
Authors: Bárány Balázs , Troscheit Sascha 
Published: September 2022

Abstract
In dynamical systems, shrinking target sets and pointwise recurrent sets are two important classes of dynamically defined subsets. In this article we introduce a mild condition on the linear parts of the affine mappings that allow us to bound the Hausdorff dimension of cylindrical shrinking target and recurrence sets. For generic self-affine sets in the sense of Falconer, that is by randomising the translation part of the affine maps, we prove that these bounds are sharp. These mild assumptions mean that our results significantly extend and complement the existing literature for recurrence on self-affine sets.
Unique data sets aid in detecting and proving contract cheating in numerical examination questions
Authors: Lim (林百君) Kieran Fergus 
Published: September 2022

Abstract
Undergraduate first-year courses are often mandatory for students in a variety of majors and degrees. Many students view these core courses as of little interest and relevance, which is associated with lack of motivation for study and can lead to cheating. Contract cheating in text-based is difficult to detect and prove. Contract cheating in numerical-calculation-based assessments is even harder to detect and prove. This paper discusses how unique identifying information can be incorporated into numerical assessments and how unique data sets can be used to both detect and prove contract cheating. Finally, some measures to discourage contract cheating are discussed.
Suggestions on the teaching of atmospheric pressure at university and secondary school levels
Authors: Giulotto Enrico , Malgieri Massimiliano 
Published: September 2022

Abstract
The distinction between pressure in a liquid and in a gas is often treated in a cursory way, or not treated at all, even in university level textbooks. Most texts fail to point out the relation between pressure and density in a gas as compared to pressure in a—virtually incompressible—liquid. In many instances this also results in a dismissive treatment of atmospheric pressure. In this paper we suggest that in the physics curriculum of university and secondary school students, kinetic theory of gases be treated before fluid mechanics and thermodynamics. In this way, the definitions of pressure P and absolute temperature T in a gas can be derived consistently, with the remarkable advantage that the links between the macroscopic parameters P and T and the velocity of molecules—a microscopic parameter—are made clear at an early stage, as well as the relation between P and density ρ.
2D-materials-integrated optoelectromechanics: recent progress and future perspectives
Authors: Peng Mingzeng , Cheng Jiadong , Zheng Xinhe , Ma Jingwen , Feng Ziyao , Sun Xiankai 
Published: September 2022

Abstract
The discovery of two-dimensional (2D) materials has gained worldwide attention owing to their extraordinary optical, electrical, and mechanical properties. Due to their atomic layer thicknesses, the emerging 2D materials have great advantages of enhanced interaction strength, broad operating bandwidth, and ultralow power consumption for optoelectromechanical coupling. The van der Waals (vdW) epitaxy or multidimensional integration of 2D material family provides a promising platform for on-chip advanced nano-optoelectromechanical systems (NOEMS). Here, we provide a comprehensive review on the nanomechanical properties of 2D materials and the recent advances of 2D-materials-integrated nano-electromechanical systems and nano-optomechanical systems. By utilizing active nanophotonics and optoelectronics as the interface, 2D active NOEMS and their coupling effects are particularly highlighted at the 2D atomic scale. Finally, we share our viewpoints on the future perspectives and key challenges of scalable 2D-materials-integrated active NOEMS for on-chip miniaturized, lightweight, and multifunctional integration applications.
Proof-of-concept study of bolt connection status monitoring using fiber Bragg grating curvature sensor
Authors: Deng Shaohua , Wang Tao , Tan Bohai , Yu Wei , Lu Guangtao 
Published: September 2022

Abstract
For connection status monitoring of bolted joint groups, a novel method with fiber Bragg grating (FBG)-based curvature sensor is proposed. An FBG curvature sensor with an inextensible elastic matrix and an offset grating is adopted and clamped between a fixed support and the monitored bolt in a plane bending status. Based on the shape deformation of the FBG curvature sensor induced by the bolt loosening, the bending curvature change of the elastic matrix is measured by the FBG. By detecting the wavelength shift of the FBG induced by the matrix curvature variation, the relationship between the bolt loosening angle and the wavelength shift of FBG can be obtained, and hence the bolt connection status can be determined by the wavelength shift of FBG. Details of the proposed method are presented, and a surface-bonded FBG curvature sensor is designed, fabricated, and experimentally studied to verify the proposed method, and the parameters on sensing performance are also investigated. Experimental results show that the proposed method can monitor bolt loosening angle with high sensitivity and linear output by adjusting the parameters of the FBG curvature sensor. The looseness angle resolution of the proposed sensor can reach 0.0767°. This paper presents the first attempt to monitor bolt loosening angle using an FBG curvature sensor. With the advantages of high sensitivity and resolution, strong applicability, convenience and reusability for the maintenance of bolts, and ease of forming quasi-distributed sensor networks, the proposed method is able to provide a general solution for the on-line monitoring of bolt connection status for large-span distributed bolted-joint groups.
Investigating the effect of transverse compressive loads on the electromagnetic performance of superconducting CORC® cables
Authors: Yan Jiangtao , Wang Keyang , Gao Yuanwen , Zhou Youhe , Nijhuis Arend 
Published: September 2022

Abstract
High-temperature superconductor (Re)Ba2Cu3O
x
(ReBCO) conductor on round core cable (CORC®) has a large current carrying capacity for high field magnets. Lorentz forces acting on CORC conductors, cause a reduction of the critical current, or even permanent degradation of their performance when exceeding critical values. Transverse compressive stress is one of the principal mechanical stresses when CORC cables are bundled to cable-in-conduit conductors (CICC) conductors capable of operating at currents up to 100 kA in magnetic fields of up to 20 T. In this research, a mechanical-electromagnetic model is developed to study the effect of transverse compressive loads on the electromagnetic performance of CORC cables. A mechanical transverse load on the cable is implemented to simulate the electromagnetic force. A comparison of numerical simulations with experiments for a three-layer CORC cable is first performed to validate the model’s reliability, with particular attention to critical current reduction during the transverse compression process. A novel feature of this paper is that the model developed can analyze both mechanical response under transverse compressive loads and electromagnetic performance under applied AC magnetic fields with low amplitudes. On this basis, the model investigates the effects of winding parameters on the axial strain and critical current reduction of the ReBCO layer in a single-layer CORC cable. The numerical analysis shows that increasing the winding angle can reduce the axial strain and critical current reduction of the ReBCO layer in the contact area. Subsequently, a detailed comparative study is carried out studying the axial strain of the ReBCO layer in the non-contact area with and without taking the winding core into account. In addition, a sudden increase in the magnetization loss is explained when the transverse compressive load reaches a certain level. Finally, a six-layer CORC cable’s electromagnetic analysis is performed, and each tape layer’s critical current reduction is investigated and discussed. The comparison of magnetization loss and current density between six- and single-layer CORC cables in the no-strain case is also given. This finite element model can guide optimizing a cable design for specific application conditions.
The correlation between structure and magneto optical properties of nanostructured Magnesium ferrites upon Molybdenum doping for magnetic and optoelectronic applicability
Authors: Desoky W M , Abd Allah T M 
Published: September 2022

Abstract
Nano-ferrite MgMoxFe2-xO4 (X = 0.0, 0.05, 0.1, 0.15, and 0.3) were synthesized employing citrate sol-gel auto combustion methodology. X-ray diffraction (XRD) reveals the crystal structure of the prepared samples. XRD scrutiny disclosed a single cubic spinel phase for all specimens. Furthermore, the Rietveld analysis based on structure refinement used to determine the microstructural parameters and evaluate the cation distribution. The findings showed that the average crystallite size was ∼39 nm, while the lattice constant ‘a’ increases with increasing Mo concentrations attributable to introducing Mo+6 to supplant Fe+3. The magnetic properties were investigated utilizing VSM magnetometer. The saturation magnetization (Ms) descends with escalating Mo+6 replacement. Consequently, both Rietveld scrutiny and saturation magnetization (Ms) results suggest that the Mo+6 supplanted Fe+3 in octahedral B-locations. On the other hand, reflectance and transmittance were used in optical properties to calculate the refractive index, n, and the extinction coefficient, k. The parameters of optical properties such as infinity, lattice and relaxation time of dielectric constant were estimated. In addition, complex optical conductivity, optical electronegativity and optical transitions of all studied samples were assessed. Finally, the parameters of opto-electrical application, such as the concentration, mobility and resistivity of optical carrier were appraised.