bluuebunny/crossref_metadata_2025 huggingface dataset:
Drag, lift, and torque coefficients for various geometrical configurations of elliptic cylinder under Stokes to laminar flow regimes
Authors: Oh Geunwoo , Park Hyunwook , Choi Jung-Il
Published: June 2022

In this study, the drag, lift, and torque coefficients are derived as a function of the axis ratio (AR) and angle of attack (AOA) for elliptic cylinders with simple and straightforward correlations in flow regimes ranging from Stokes to laminar flow. An immersed boundary method, based on an implicit direct forcing scheme to impose a more accurate no-slip condition for viscous flow, is utilized to compute the hydrodynamic forces on the elliptic cylinder. Numerical simulations are performed for two-dimensional flow around an elliptic cylinder. The ARs and AOAs of the elliptic cylinder are within 0.3–1.0 and 0°–90°, respectively. A critical Reynolds number (Recrt) map is obtained, indicating a transition between steady and unsteady flows as a function of the AR and AOA. Based on Recrt for the circular cylinder, it is observed that a more prolonged elliptic cylinder delays Recrt to a higher Re value at low AOAs but causes an unsteady transition at a lower Re value when the AOA exceeds ∼30°. The correlations are selected as simple functions, such as power laws and trigonometric functions, based on the hydrodynamic force behaviors according to variations in the AR, AOA, and Re. The prediction accuracy of the proposed correlations assessed in terms of mean relative errors is ∼1.5%, 8.9%, and 11.2% for drag, lift, and torque, respectively. This comparison demonstrates that the proposed correlations are suitable for accurately predicting hydrodynamic forces in Stokes to laminar flow regimes, even when using simple basic forms.
Cavity-induced non-adiabatic dynamics and spectroscopy of molecular rovibrational polaritons studied by multi-mode quantum models
Authors: Fischer Eric W. , Saalfrank Peter
Published: June 2022

We study theoretically the quantum dynamics and spectroscopy of rovibrational polaritons formed in a model system composed of a single rovibrating diatomic molecule, which interacts with two degenerate, orthogonally polarized modes of an optical Fabry–Pérot cavity. We employ an effective rovibrational Pauli–Fierz Hamiltonian in length gauge representation and identify three-state vibro-polaritonic conical intersections (VPCIs) between singly excited vibro-polaritonic states in a two-dimensional angular coordinate branching space. The lower and upper vibrational polaritons are of mixed light–matter hybrid character, whereas the intermediate state is purely photonic in nature. The VPCIs provide effective population transfer channels between singly excited vibrational polaritons, which manifest in rich interference patterns in rotational densities. Spectroscopically, three bright singly excited states are identified when an external infrared laser field couples to both a molecular and a cavity mode. The non-trivial VPCI topology manifests as pronounced multi-peak progression in the spectral region of the upper vibrational polariton, which is traced back to the emergence of rovibro-polaritonic light–matter hybrid states. Experimentally, ubiquitous spontaneous emission from cavity modes induces a dissipative reduction of intensity and peak broadening, which mainly influences the purely photonic intermediate state peak as well as the rovibro-polaritonic progression.
Membrane shape deformation induced by curvature-inducing proteins consisting of chiral crescent binding and intrinsically disordered domains
Authors: Noguchi Hiroshi
Published: June 2022

Curvature-inducing proteins containing a bin/amphiphysin/Rvs domain often have intrinsically disordered domains. Recent experiments have shown that these disordered chains enhance curvature sensing and generation. Here, we report on the modification of protein–membrane interactions by disordered chains using meshless membrane simulations. The protein and bound membrane are modeled together as a chiral crescent protein rod with two excluded-volume chains. As the chain length increases, the repulsion between them reduces the cluster size of the proteins. It induces spindle-shaped vesicles and a transition between arc-shaped and circular protein assemblies in a disk-shaped vesicle. For flat membranes, an intermediate chain length induces many tubules owing to the repulsion between the protein assemblies, whereas longer chains promote perpendicular elongation of tubules. Moreover, protein rods with zero rod curvature and sufficiently long chains stabilize the spherical buds. For proteins with a negative rod curvature, an intermediate chain length induces a rugged membrane with branched protein assemblies, whereas longer chains induce the formation of tubules with periodic concave-ring structures.
Spectroscopic identification and characterization of the aluminum methylene (AlCH2) free radical
Authors: Sunahori Fumie X. , Smith Tony C. , Clouthier Dennis J.
Published: June 2022

The AlCH2 free radical has been spectroscopically identified for the first time. This highly reactive species was produced in an electric discharge jet using trimethylaluminum vapor in high pressure argon as the precursor. The laser-induced fluorescence spectrum of the B̃2A2−X̃2B1 band system in the 513–483 nm region was recorded, and the 0–0 bands of AlCH2 and AlCD2 were studied at high resolution. The fine structure splittings were found to be due primarily to the Fermi contact interaction in the excited state rather than the usual spin–rotation coupling. Rotational analysis gave the molecular constants of the combining states, and the geometries were obtained as r″A1−C=1.9591A◦,r″C−H=1.1061A◦,θHCH″=110.41◦ and r′A1−C=1.9431A◦,r′C−H=1.0911A◦,θHCH′=115.41◦. The bond lengths correspond to an aluminum–carbon single bond in both states.
L2 speaking and its internal correlates
Authors: Koizumi Rie , In'nami Yo , Jeon Eun Hee
Published: June 2022

The current meta-analysis examines relationships between second-language (L2) speaking (assessed using global ratings) and its internal features, such as fluency and accuracy (assessed using analytic ratings or measures) that were derived by analyzing speaking performance during the same speaking tasks. A synthesis of 39 studies (284 correlations) suggests that internal features are strongly correlated to L2 speaking in general (r = .649) and that the strength of the correlations varies according to oral features (e.g., r = .713 to .888 for fluency, delivery, grammar, vocabulary, pronunciation, and content). The results highlight the relative importance of various internal features in L2 speaking and suggest areas in need of further research.
L2 speaking and its external correlates
Authors: Jeon Eun Hee , In'nami Yo , Koizumi Rie
Published: June 2022

The present study synthesizes the correlation coefficients between discourse-level L2 speaking and nine relevant correlates: L2 vocabulary knowledge, L2 grammar knowledge, working memory, L2 reading comprehension, L2 listening comprehension, L2 writing, language aptitude, metacognition, and anxiety. Fifty-one independent samples from 41 primary studies publlished between 1975 and 2017 were included in the study. Correlations weighted for sample size and, when possible, corrected for attenuation due to measurement errors were submitted to a series of nine quantitative meta-analyses. The results showed that L2 knowledge variables were strongly correlated with L2 speaking (.563 for vocabulary and .622 for grammar). The same results were found for companion L2 proficiency variables such as L2 reading comprehension (.822), L2 listening comprehension (.530), and L2 writing (.605). As for the language general variables, metacognition was much more strongly correlated with L2 speaking (.624) compared to working memory (.102). Lastly, language aptitude and anxiety each showed a positive and a negative correlation falling in the medium to large range: .481 for language aptitude and −.432 for anxiety.
Twisted electron impact single ionization coincidence cross-sections for noble gas atoms
Authors: Dhankhar Nikita , Banerjee Soham , Choubisa R
Published: June 2022

We present the angular profiles of the triple differential cross-section (TDCS) for the (e, 2e) process on the noble gas atoms, namely He (1s), Ne (2s and 2p), and Ar (3p), for the plane wave and the twisted electron impact. We develop the theoretical formalism in the first Born approximation (FBA). The present study compares the TDCS for different values of orbital angular momentum number m and opening angles θ

p
of the twisted electron beam with that of the plane wave beam in co-planar asymmetric geometry. In addition, we also investigate the TDCS for macroscopic targets to explore the influence of the opening angle θ

p
of the twisted electron beam on the TDCS. Our results show that the peaks in binary and recoil regions shift from the momentum transfer direction. The results also show that for larger opening angles, the peaks for p-type orbitals split into double-peak structures, which are not observed in the plane wave results for the given kinematics. The angular profiles for averaged cross-section show the dependence of TDCS on the opening angles, especially for the larger opening angles, which are significantly different from the plane wave TDCS.
X-ray absorption of molecular cations—a new challenge for electronic structure theory
Authors: Carravetta V , Couto R C , Ågren H
Published: June 2022

In this paper we put forward some historical notes on the development of computational chemistry toward applications of x-ray spectroscopies. We highlight some of the important contributions by Enrico Clementi as method and program developer and as a supporter of this branch of computational research. We bring up a modern example based on the very recent experimental development of x-ray absorption of cationic molecules. As we show this spectroscopy poses new challenges for electronic structure theory and the electron correlation problem.
Magnetoquantum oscillations in the specific heat of a topological Kondo insulator
Authors: LaBarre P G , Rydh A , Palmer-Fortune J , Frothingham J A , Hannahs S T , Ramirez A P , Fortune N A
Published: June 2022

Surprisingly, magnetoquantum oscillations (MQOs) characteristic of a metal with a Fermi surface have been observed in measurements of the topological Kondo insulator SmB6. As these MQO have only been observed in measurements of magnetic torque (dHvA) and not in measurements of magnetoresistance (SdH), a debate has arisen as to whether the MQO are an extrinsic effect arising from rare-earth impurities, defects, and/or aluminum inclusions or an intrinsic effect revealing the existence of charge-neutral excitations. We report here the first observation of MQO in the low-temperature specific heat of SmB6. The observed frequencies and their angular dependence for these flux-grown samples are consistent with previous results based on magnetic torque for SmB6 but the inferred effective masses are significantly larger than previously reported. Such oscillations can only be observed if the MQO are of bulk thermodynamic origin; the measured magnetic-field dependent oscillation amplitude and effective mass allow us to rule out suggestions of an extrinsic, aluminum inclusion-based origin for the MQO.
Computational analysis of the enhancement of photoelectrolysis using transition metal dichalcogenide heterostructures
Authors: Baker Edward A D , Pitfield Joe , Price Conor J , Hepplestone Steven P
Published: June 2022

Finding a material with all the desired properties for a photocatalytic water splitter is a challenge yet to be overcome, requiring both a surface with ideal energetics for all steps in the hydrogen and oxygen evolution reactions (HER and OER) and a bulk band gap large enough to mediate said steps. We have instead examined separating these challenges by investigating the energetic properties of two-dimensional transition metal dichalcogenides (TMDCs) that could be used as a surface coating to a material with a large enough bulk band gap. First we investigated the energetics of monolayer MoS2 and PdSe2 using density functional theory and then investigated how these energetics changed when they were combined into a heterostructure. Our results show that the surface properties were practically (

<

0.2 eV) unchanged when combined and the MoS2 layer aligns well with the OER and HER. This work highlights the potential of TMDC monolayers as surface coatings for bulk materials that have sufficient band gaps for photocatalytic applications.
Reflectionless Klein tunneling of Dirac fermions: comparison of split-operator and staggered-lattice discretization of the Dirac equation
Authors: Donís Vela A , Lemut G , Pacholski M J , Tworzydło J , Beenakker C W J
Published: June 2022

Massless Dirac fermions in an electric field propagate along the field lines without backscattering, due to the combination of spin-momentum locking and spin conservation. This phenomenon, known as ‘Klein tunneling’, may be lost if the Dirac equation is discretized in space and time, because of scattering between multiple Dirac cones in the Brillouin zone. To avoid this, a staggered space-time lattice discretization has been developed in the literature, withonesingle Dirac cone in the Brillouin zone of the original square lattice. Here we show that the staggering doubles the size of the Brillouin zone, which actually containstwoDirac cones. We find that this fermion doubling causes a spurious breakdown of Klein tunneling, which can be avoided by an alternative single-cone discretization scheme based on a split-operator approach.
Electron-impact ionization cross sections of small molecules containing Fe and Cr
∗
Authors: Romero José , Limão-Vieira Paulo , Probst Michael
Published: June 2022

We present the electron-impact ionization cross sections (EICSs) of iron and chromium hydrides, nitrides, and oxides. The motivation of this work stems from the fact that chemical sputtering from a steel surface exposed to a hot plasma can create these molecules which in turn influence the composition and energy balance of the plasma. The latter influence is quantified by the EICS which we derive by using two semi-empirical methods which can be employed in the relevant energy range of 10–1000 eV. They are important molecular properties for plasma- and materials science. We discuss the foundations of the methods and present the cross sections of the high- and low-spin states of the species in their neutral ground states and of their cations.
Explainable 1DCNN with demodulated frequency features method for fault diagnosis of rolling bearing under time-varying speed conditions
Authors: Lu Feiyu , Tong Qingbin , Feng Ziwei , Wan Qingzhu , an Guoping , Li Yilei , Wang Meng , Cao Junci , Guo Tao
Published: June 2022

Intelligent fault diagnosis of rolling bearings under non-stationary and time-varying speed conditions is still a challenging task. At the same time, a reasonable explanation for an intelligent diagnosis model based on features is currently lacking. Therefore, we exploit an explainable one-dimensional convolutional neural network (1DCNN) model by combining with the demodulated frequency features of vibration signals and apply it to the fault classification of rolling bearings under time-varying speed conditions. First, the speed signals obtained by the speed encoder were transformed into generalized demodulation operator (GDO). Second, combined with the sensitive frequency band and GDO, the generalized demodulation algorithm was used to extract the frequency features from the amplitude envelope of the vibration signal. Subsequently, the proposed lightweight 1DCNN was trained to classify the frequency features and identify the health states of the rolling bearing. Finally, the local interpretable model-agnostic explanations model was utilized to explain the proposed model based on the features which own weight. It is found that the internal classification mechanism of the lightweight 1DCNN is realized according to the distribution of fault features, which is consistent with the process of human brain analysis. Two kinds of time-varying speed datasets which come from the University of Ottawa and XJTU are tested and verified. The results show that compared with other intelligent fault diagnosis methods, the identification error of the proposed method is lower and the diagnosis stability is better. The average diagnostic accuracy was 96.26% and 99.82%, respectively.
Precision profile measurement of disc surface by error motion compensation
Authors: Hwang In-Oh , Seo Se-Min , Cho Nahm-Gyoo
Published: June 2022

In this study, a precision measurement method to obtain the surface profile of a rotating disc is proposed. To improve the accuracy of the estimated profile, the 3-DOF error motion included in the measured surface profile signal is simultaneously estimated and compensated. The profile of the disc is measured using a surface measuring unit equipped with one displacement sensor, and the error motion of the rotating component is measured using an error motion measuring unit equipped with a four-probe system. The developed error motion measuring unit uses a four-probe error separation technique, and the effect of zero setting errors between the probes on the compensated surface profile is analyzed. Subsequently, a process to remove the effect is proposed. To confirm the performance of the proposed method, numerical verification tests and experiments are performed using test equipment. The numerical verification tests show that the developed measuring system affords accurate shape estimation and is not affected by zero setting errors between probes. The experimental results of surface profile measurement using the proposed measurement method and the conventional one probe method are compared. The standard deviation of the measuring results using the proposed method was smaller than that of the conventional method by less than two-thirds. From this, it can be concluded that the error motions have been effectively compensated.
Fault feature analysis and detection of progressive localized gear tooth pitting and spalling
Authors: Luo Yang , Wang Hao , Shi Juanjuan , Yang Shuai , Baddour Natalie , Liang Ming
Published: June 2022

Fault feature analysis of gear tooth spalling plays a vital role in gear fault diagnosis. Understanding how fault features evolve as a fault progresses is key to fault severity assessment. Due to the complicated nature of gear meshing, fault features and their development as the fault severity progresses remain mostly unknown. The assessment of fault severity is generally based on the hypothesis that ‘the more severe the fault, the stronger the fault symptom’, an assumption that has not been experimentally validated. This paper provides a comprehensive, experimental analysis of the evolution of fault vibration features of a gear transmission with progressive localized gear tooth spalling. The effects of rotational speed on the vibration features of the gear transmission are analysed. Changes in fault features (e.g. periodic impulses and sideband phenomena) under different fault severity levels and speed conditions are compared. Results indicate that the number, amplitude and distribution of sidebands increase nonlinearly as the fault progresses. Based on feature analysis, a new health indicator of the mean of the nth order peaks is proposed to detect progressive localized tooth spalling. Results indicate that the proposed indicator shows very good performance for tracking the severity of progressive tooth spalling under different speed conditions.
An enhanced high frequency performance SiC MOSFET with self-adjusting P-shield region potential
Authors: Xing Yunpeng , Deng Xiaochuan , Wu Hao , Xu Xiaojie , Li Xu , Li Xuan , Wen Yi
Published: June 2022

An enhanced high frequency (HF) performance SiC metal oxide semiconductor field effect transistor (MOSFET) with self-adjusting P-shield region potential (SA-MOS) is proposed and characterized in this paper. The potential of P-shield region (ground or floating potential) can be adjusted by a depletion P-channel metal oxide semiconductor field effect transistor (PMOS) structure integrated in the SA-MOS. During turn-on of SA-MOS, the channel of integrated PMOS is pinched off and the P-shield region can be at a floating potential. Therefore, SA-MOS shows about 21% specific on-resistance (R
on,sp) reduction as compared to the conventional trench gate SiC MOSFET with grounded P-shield (GP-MOS) due to the retraction of depletion layer in drift region. During turn-off of SA-MOS, the integrated PMOS is turned on and the P-shield region is grounded to the source contact. Thus, the high on-state oxide electric field and slower switching speed caused by the floating P-shield region could be eliminated by SA-MOS structure. Furthermore, the gate-to-drain charge (Q
gd) of SA-MOS is only 217 nC cm−2 owing to smaller overlap area between drift region and trench gate, which is about 40% lower than that of GP-MOS. The HF figures of merit (HF-FOM= R
on,sp × Q
gd) for SA-MOS can be as low as 50% or more of GP-MOS. Finally, an analytical model is also developed to describe the variation of P-shield potential in SA-MOS. With the overall improved performance, SA-MOS shows a significant advantage in HF field in comparison with the GP-MOS.
Fluorine-containing organic ammonium salt-doped inverted inorganic perovskite solar cells
Authors: Shi Kewang , Zhang Fanghui , Zhang Meng , Chen Chunyang , Zhang Wenxi , Huang Jin
Published: June 2022

Inorganic lead halide perovskites have a reasonable energy bandgap, which makes them ideal for tandem devices. As a result, inorganic lead halide perovskite solar cells (PSCs) could be prospective next-generation solar materials, but the issue of instability under moisture remains unaddressed. Adding 4-fluoro-phenyl-ethylammonium iodide (F-PEAI) spacer cations to the perovskite precursor solution is an elementary addition method to improve the performance of PSCs. We study the impact of F-PEAI on the perovskite crystal phase and the effect of F-PEAI concentration on PSC performance. F-PEAI was used to passivate interfacial flaws and vacancies in inverted inorganic PSCs and improve moisture tolerance, resulting in a mixed 2D/3D heterostructure. A small number of F-PEAI-treated PSCs have changed interfacial characteristics, resulting in better charge extraction and less charge recombination. The power conversion efficiency (PCE) of the F-PEAI treated device is much higher than that of the control group, and the PCE is improved to more than 11%. To attain high efficiency, all-inorganic perovskites can be modified using a straightforward method.
Kinematics and shear-induced alignment in confined granular flows of elongated particles
Authors: Pol Antonio , Artoni Riccardo , Richard Patrick , Nunes da Conceição Paulo Ricardo , Gabrieli Fabio
Published: June 2022

The kinematics and the shear-induced alignment of elongated particles in confined, heterogeneous flow conditions are investigated experimentally. Experiments are conducted in an annular shear cell with a rotating bottom wall and a top wall permitting confinement of the flow. Flow kinematics and particle orientation statistics are computed by particle tracking using optical imaging. Translational velocity profiles show an exponential decay, and surprisingly, only the slip velocity at the bottom is influenced by the particle shape. Rotations are highly frustrated by particle shape, more elongated particles showing, on average, a lower angular velocity. In addition, a clear shear-rate dependency of the proneness of a particle to rotate is observed, with a stronger inhibition in low shear zones. The average orientation of the particles does not correspond to the main flow direction, they are slightly tilted downwards. The corresponding angle decreases with the particles’ elongation. Orientational order was observed to increase with particles’ elongation, and surprisingly was not affected by the applied confinement. A weak but systematic decrease of the orientational order was observed in regions of higher shear rate. At the particle-scale, angular velocity fluctuations show a strong correlation with local particle orientation, particles being strongly misaligned with the preferential particles’ orientation rotating faster. This correlation becomes stronger for more elongated particles, while is almost unaffected by the applied confinement.
Surface plasmon-driven electron and proton acceleration without grating coupling
Authors: Sarma J , McIlvenny A , Das N , Borghesi M , Macchi A
Published: June 2022

Surface plasmon (SP) excitation in intense laser interaction with solid target can be exploited for enhancing secondary emissions, in particular efficient acceleration of high charge electron bunches. Previous studies have mostly used grating coupling to allow SP excitation, which requires stringent laser contrast conditions to preserve the structural integrity of the target. Here we show via simulations that efficient SP electron acceleration for currently available short pulse lasers can occur in a flat foil irradiated at parallel or grazing incidence (

∼
5
°

with the target surface) without a surface modulation. In turn, the accelerated electrons can be effective for generating proton beams with narrow spectra peaked at

>

100 MeV energies for currently available laser drivers.
First and second sound in a dilute Bose gas across the BKT transition
Authors: Singh Vijay Pal , Mathey Ludwig
Published: June 2022

We study the propagation of the two sound modes in two-dimensional Bose gases across the Berezinksii–Kosterlitz–Thouless transition using classical-field dynamics, which is motivated by recent measurements of Christodoulou et al (2021 Nature
594 191). Based on the dynamic structure factor (DSF), we identify the two sound modes as the Bogoliubov (B) and the non-Bogoliubov (NB) sound mode below the transition, and as the diffusive and the normal sound mode above the transition. The NB sound mode velocity is higher than the B sound mode velocity, which we refer to as the weak-coupling regime of the sound modes. We excite the sound modes by driving the system as in the experiment and by perturbing the density with a step-pulse perturbation, as a secondary comparison. The driven response depends on the driving strength and results in higher velocities for the B sound mode at high temperatures near the transition, compared to the sound results of the DSF and step-pulse excitation. We show that the higher mode velocity has a weak temperature dependence across the transition, which is consistent with the experimental observation.
Geminga contribution to the cosmic-ray positron excess according to the gamma-ray observations
Authors: Zhou Guang-Yao , Yu Zhao-Huan , Yuan Qiang , Zhang Hong-Hao
Published: June 2022

We attempt to interpret the cosmic-ray positron excess by injection from the nearby pulsar Geminga, assuming a two-zone diffusion scenario and an injection spectrum with a low energy cutoff. Since the high energy positrons and electrons from Geminga can induce γ rays via inverse Compton scattering, we take into account the extended γ-ray observations around Geminga from HAWC for ∼10 TeV and from Fermi-LAT for


(
10
)

GeV. According to the extended γ-ray observation claimed by an analysis of Fermi-LAT data, we find that Geminga could explain the positron excess for a 30% energy conversion efficiency into positrons and electrons. However, based on the constraint on the extended γ rays given by another Fermi-LAT analysis, positrons from Geminga would be insufficient to account for the positron excess. Further robust analysis of Fermi-LAT data for the extended γ rays would be crucial to determine whether Geminga can explain the positron excess or not.
The ringing of quantum corrected Schwarzschild black hole with GUP
Authors: Xing Yujia , Yang Yi , Liu Dong , Long Zheng-Wen , Xu Zhaoyi
Published: June 2022

Schwarzschild black holes with quantum corrections are studied under scalar field perturbations and electromagnetic field perturbations to analyze the effect of the correction term on the potential function and quasinormal mode (QNM). In classical general relativity, spacetime is continuous and there is no existence of the so-called minimal length. The introduction of the correction items of the generalized uncertainty principle, the parameter β, can change the singularity structure of the black hole gauge and may lead to discretization in time and space. We apply the sixth-order WKB method to approximate the QNM of Schwarzschild black holes with quantum corrections and perform numerical analysis to derive the results of the method. Also, we find that the effective potential and QNM in scalar fields are larger than those in electromagnetic fields.
Searching for isotropic stochastic gravitational-wave background in the international pulsar timing array second data release
Authors: Chen Zu-Cheng , Wu Yu-Mei , Huang Qing-Guo
Published: June 2022

We search for isotropic stochastic gravitational-wave background (SGWB) in the International Pulsar Timing Array second data release. By modeling the SGWB as a power-law, we find very strong Bayesian evidence for a common-spectrum process, and further this process has scalar transverse (ST) correlations allowed in general metric theory of gravity as the Bayes factor in favor of the ST-correlated process versus the spatially uncorrelated common-spectrum process is 30 ± 2. The median and the 90% equal-tail amplitudes of ST mode are



ST

=

1.29

−
0.44

+
0.51

×

10

−
15

, or equivalently the energy density parameter per logarithm frequency is

Ω
GW
ST

=

2.31

−
1.30

+
2.19

×

10

−
9

, at frequency of 1 year−1. However, we do not find any statistically significant evidence for the tensor transverse (TT) mode and then place the 95% upper limits as



TT

<
3.95
×

10

−
15

, or equivalently

Ω
GW
TT

<
2.16
×

10

−
9

, at frequency of 1 year−1.
Lattice damage in InGaN induced by swift heavy ion irradiation
Authors: Liu Ning , Zhang Li-Min , Liu Xue-Ting , Zhang Shuo , Wang Tie-Shan , Guo Hong-Xia
Published: June 2022

The microstructural responses of In0.32Ga0.68N and In0.9Ga0.1N films to 2.25 GeV Xe ion irradiation have been investigated using x-ray diffraction, Raman scattering, ion channeling and transmission electron microscopy. It was found that the In-rich In0.9Ga0.1N is more susceptible to irradiation than the Ga-rich In0.32Ga0.68N. Xe ion irradiation with a fluence of 7 × 1011 ions⋅cm−2 leads to little damage in In0.32Ga0.68N but an obvious lattice expansion in In0.9Ga0.1N. The level of lattice disorder in In0.9Ga0.1N increases after irradiation, due to the huge electronic energy deposition of the incident Xe ions. However, no Xe ion tracks were observed to be formed, which is attributed to the very high velocity of 2.25 GeV Xe ions. Point defects and/or small defect clusters are probably the dominant defect type in Xe-irradiated In0.9Ga0.1N.
Graph dynamical networks for forecasting collective behavior of active matter
Authors: Liu Yanjun , Wang Rui , Zhao Cai , Zheng Wen
Published: June 2022

After decades of theoretical studies, the rich phase states of active matter and cluster kinetic processes are still of research interest. How to efficiently calculate the dynamical processes under their complex conditions becomes an open problem. Recently, machine learning methods have been proposed to predict the degree of coherence of active matter systems. In this way, the phase transition process of the system is quantified and studied. In this paper, we use graph network as a powerful model to determine the evolution of active matter with variable individual velocities solely based on the initial position and state of the particles. The graph network accurately predicts the order parameters of the system in different scale models with different individual velocities, noise and density to effectively evaluate the effect of diverse condition. Compared with the classical physical deduction method, we demonstrate that graph network prediction is excellent, which could save significantly computing resources and time. In addition to active matter, our method can be applied widely to other large-scale physical systems.
Ozone oxidation of 4H-SiC and flat-band voltage stability of SiC MOS capacitors
Authors: Yin Zhi-Peng , Wei Sheng-Sheng , Bai Jiao , Xie Wei-Wei , Liu Zhao-Hui , Qin Fu-Wen , Wang De-Jun
Published: June 2022

We investigate the effect of ozone (O3) oxidation of silicon carbide (SiC) on the flat-band voltage (V
fb) stability of SiC metal–oxide–semiconductor (MOS) capacitors. The SiC MOS capacitors are produced by O3 oxidation, and their V
fb stability under frequency variation, temperature variation, and bias temperature stress are evaluated. Secondary ion mass spectroscopy (SIMS), atomic force microscopy (AFM), and x-ray photoelectron spectroscopy (XPS) indicate that O3 oxidation can adjust the element distribution near SiC/SiO2 interface, improve SiC/SiO2 interface morphology, and inhibit the formation of near-interface defects, respectively. In addition, we elaborate the underlying mechanism through which O3 oxidation improves the V
fb stability of SiC MOS capacitors by using the measurement results and O3 oxidation kinetics.
Terahertz spectroscopy and lattice vibrational analysis of pararealgar and orpiment
Authors: Zhang Ya-Wei , Ren Guan-Hua , Su Xiao-Qiang , Meng Tian-Hua , Zhao Guo-Zhong
Published: June 2022

Terahertz time-domain spectroscopy (THz-TDS) is an effective nondestructive and noninvasive tool for investigating sulfur-containing pigments. Combined with Raman spectroscopy and vibrational mode analysis, it is significant for artifact identification and conservation. In this work, the terahertz absorption spectra of pararealgar (As4S4) and orpiment (As2S3) samples mixed with polytetrafluoroethylene (PTFE) are characterized in a range from 0.2 THz to 2.2 THz, and their distinctive peaks are observed, respectively. Meanwhile, qualitative analysis is also implemented by using Raman spectroscopy as a complementary technique. The lattice vibrations are simulated by using solid-state density functional theory (ss-DFT), illustrating different characteristic absorption peaks for specific crystalline structures and dynamic properties. This work provides a reliable database of sulfur-containing pigments for using the THz technology to actually analyze and diagnose cultural relics.
Strain compensated type II superlattices grown by molecular beam epitaxy
Authors: Ning Chao , Yu Tian , Sun Rui-Xuan , Liu Shu-Man , Ye Xiao-Ling , Zhuo Ning , Wang Li-Jun , Liu Jun-Qi , Zhang Jin-Chuan , Zhai Shen-Qiang , Liu Feng-Qi
Published: June 2022

We investigate a strain compensation method for the growth of complex interband cascade laser structures. For thick InAs/AlSb superlattice clad layers, the sublayer thicknesses were adjusted so that the tensile strain energy in the InAs sublayer was equal to the compressive strain energy in the AlSb sublayer. For the four-constituent active region, as the compressive strain in the Ga0.65In0.35Sb alloy layer was large, a tensile strain was incorporated in the chirped InAs/AlSb superlattice region for strain compensation to the Ga0.65In0.35Sb alloy. A laser structure of thickness 6 μm was grown on the GaSb substrate by molecular beam epitaxy. The wafer exhibited good surface morphology and high crystalline quality.
High performance SiC trench-type MOSFET with an integrated MOS-channel diode
Authors: Wei Jie , Jiang Qinfeng , Luo Xiaorong , Huang Junyue , Yang Kemeng , Ma Zhen , Fang Jian , Yang Fei
Published: June 2022

A novel SiC double-trench metal-oxide-semiconductor field effect transistor (MOSFET) with integrated MOS-channel diode is proposed and investigated by Sentaurus TCAD simulation. The new SiC MOSFET has a trench gate and a stepped-trench source, and features an integrated MOS-channel diode on the top sidewall of the source trench (MT MOS). In the reverse conduction state, the MOS-channel diode turns on firstly to prevent the internal parasitic body diode being activated, and thus reduces the turn-on voltage V
F and suppresses the bipolar degradation phenomena. The V
F of 1.70 V (@I
ds = –100 A/cm2) for the SiC MT MOS is 38.2% lower than that of SiC double-trench MOSFET (DT MOS). Meanwhile, the reverse recovery charge Q
rr of the MT MOS is 58.7% lower than that of the DT MOS at I
load = 700 A/cm2, and thus the reverse recovery loss is reduced. Furthermore, owing to the modulation effect induced by the double trenches, the MT MOS preserves the same superior forward conduction and blocking performance as those of DT MOS, with 22.9% and 18.2% improvement on breakdown voltage and R
ON,sp compared to the trench gate MOSFET with planar integrated SBD (ST MOS).
Underwater robot coordination using a bio-inspired electrocommunication system
Authors: Zhou Yang , Wang Wei , Zhang Han , Zheng Xingwen , Li Liang , Wang Chen , Xu Gang , Xie Guangming
Published: June 2022

Due to the challenging communication and control systems, few underwater multi-robot coordination systems are currently developed. In nature, weakly electric fish can organize their collective activities using electrocommunication in turbid water. Inspired by this communication mechanism, we developed an artificial electrocommunication system for underwater robots in our previous work. In this study, we coordinate a group of underwater robots using this bio-inspired electrocommunication. We first design a time division multiple access (TDMA) network protocol for electrocommunication to avoid communication conflicts during multi-robot coordination. Then, we revise a distributed controller to coordinate a group of underwater robots. The distributed controller on each robot generates the required controls based on adjacent states obtained through electrocommunication. A central pattern generator (CPG) controller is designed to adjust the speed of individuals according to distributed control law. Simulations and experimental results show that a group of underwater robots is able to achieve coordination with the developed electrocommunication and control systems.
Mechanical compressive behavior of pomelo peel and multilayer polymeric film/foam systems
Authors: Zhang Ziyou , Olah Anderw , Baer Eric
Published: June 2022

The study of natural cellular materials offers valuable insights into the superior properties and functions underlying their unique structure and benefits the design and fabrication of advanced biomimetic materials. In this study, we present a systematic investigation of the mechanical behavior of fresh and oven-dried pomelo peels. Density measurements revealed the gradient structure of the pomelo peel, which contributed to its mechanical properties. Step-by-step drying revealed two types of water in the peel. Both uniaxial compression and low-strain hysteresis tests were conducted, and the results showed that fresh pomelo peel exhibits soft elastomer-like behavior, while dried pomelo peel behaves more like conventional synthetic polymer foam. Compared to fresh pomelo peel, dried peel samples showed higher compressive modulus and energy loss in 6, 8 and 10% strain hysteresis tests. The rehydration process was studied using hysteresis tests at three different strains. In addition, multilayer gradient EO/EO and LDPE/LDPE film/foams with 16 alternating layers were produced using the microlayer coextrusion technique. The morphology and mechanical properties were examined and indicated great potential for biomimicking the structure and properties of pomelo peel.
Context-independent mapping and free choice are equivalent: a general proof
Authors: Dzhafarov Ehtibar N
Published: June 2022

Free choice (or statistical independence) assumption in a hidden variable model (HVM) means that the settings chosen by experimenters do not depend on the values of the hidden variable. The assumption of context-independent (CI) mapping in an HVM means that the results of a measurement do not depend on settings for other measurements. If the measurements are spacelike separated, this assumption is known as local causality. Both free choice and CI mapping assumptions are considered necessary for derivation of the Bell-type criteria of contextuality/nonlocality. It is known, however, for a variety of special cases, that the two assumptions are not logically independent. We show here, in complete generality, for any system of random variables with or without disturbance/signaling, that an HVM that postulates CI mapping is equivalent to an HVM that postulates free choice. If one denies the possibility that a given empirical scenario can be described by an HVM in which measurements depend on other measurements’ settings, free choice violations should be denied too, and vice versa.
II International scientific and practical conference “Ensuring sustainable development in the context of agriculture, green energy, ecology and earth science” (ESDCA-II-2022)
Authors: Terentyev Sergey , Romanova Iraida , Gibadullin Arthur
Published: June 2022

Within the framework of the presented material, the results of the conducted II International scientific and practical conference “Ensuring sustainable development in the context of agriculture, green energy, ecology and earth science” (ESDCA-II-2022).

International Program Committee II International scientific and practical conference “Ensuring sustainable development in the context of agriculture, green energy, ecology and earth science” (ESDCA-II-2022) are available in the pdf
Scientific support of innovative development of agriculture
Authors: Mamai O V , Bondin I A , Potenko T A , Mamai I N
Published: June 2022

This article is devoted to the problem of innovative development of agriculture and the identification of the necessary conditions for this. In the course of the study, it was found that insufficient attention is paid to the innovative development of agriculture, although the way out of agriculture from a crisis state, ensuring the competitiveness of domestic food, and its sustainable functioning directly depend on the activation of innovative processes. Therefore, it is currently relevant to develop an optimal approach to the formation of a unified system of innovative development of agriculture. The study showed that one of the ways to solve this problem is to create an effective system of scientific and information support that ensures the rapid introduction of scientific developments into mass production, which will contribute to the formation of favorable conditions for the innovative development of agriculture and the achievement of targets for ensuring the country’s food security.
Future pem fuel cell system renewable energy systems based on hydrogen equipment for microgrid networks
Authors: Chaouki Ilyes , Fedorovich Kalinin Vyacheslav
Published: June 2022

The simulation results of a modest 6 KW fuel cell energy system employing technical control are presented in this study. Technical control and fuzzy logic the performance of the controller used for maximum power point tracking (MPPT) can improve the efficiency of the FC system when Particle Swarm Optimization (PSO) and the system Boost DC/DC Converter power converter that steps up voltage (while stepping down current) from its input (supply) to its output (load) are compared. An electrolyzer with a proton exchange membrane fuel cell (PEMFC). This paper presents dynamic modeling of various components of a small isolated system. The dynamic modeling of this nonlinear 45 Vdc energy system is done with Simulink. The simulation findings are analyzed, as well as the constraints of a fuel cell energy system. The hydrogen produced is used by the third operating subsystem (the fuel cell stack), which generates electricity to power the DC bus. The global system is modeled, and the results are presented and analyzed. Due to its better efficiency, clean operation, and cost-effective supply of power sought by consumers, fuel cell (FC) technology has attracted substantial attention as an alternative to traditional power units among the numerous renewable energy sources. In the SIMULINK environment, the proposed model is implemented. The simulation outcomes are examined.
Using a Micro-grid to solve the problem of power outages and shortages in southern Algeria during the summer
Authors: Chaouki Ilyes , Fedorovich Kalinin Vyacheslav
Published: June 2022

Technological advancements have transformed the energy sector in the last few years, the industry is increasingly embracing micro-grids as a viable tool for integrating distributed generations, enhancing power quality, and guaranteeing energy supply to critical loads. Ideally, the micro-grid concept provides a viable solution to the energy sector, particularly with enormous microgeneration deployment. It addresses challenges attributed to geographically dispersed energy resources, including negative impacts on energy system operations and security. The specific climatic conditions of the desert, particularly the high temperatures in summer, greatly influence the consumption pattern in the isolated grids of southern Algeria. These extreme temperatures sometimes surpass 50 degrees, resulting in increased air conditioning systems. When operated at total capacity, especially during hot seasons, these systems significantly increase pick demands and weaken the production system enormously. Southern Algeria is considered one of the hottest places globally, which justifies its enormous power consumption due to the widespread use of cooling systems. Such consumption often leads to power cuts and shortages; thus, the need to pursue Micro-grid Integrated Hybrid System. This system integrates multiple electrical components connected through a robust distribution system. Such a hybrid renewable energy system is viable in this region because of its characteristic high solar radiation and strong winds throughout the year. Thus, this study utilized such energy resources to address Algeria’s energy shortages and power cuts using the MATLAB/Simulink program.
Toxic elements of hazard class I in ornamental herbal permanent plants
Authors: Reut A A , Beksheneva L F
Published: June 2022

Technogenic emission of heavy metals (HM) leads to their accumulation and migration in the “soil-plant” system. Herbaceous perennials occupy a significant place among the landscaping components exposed to toxicants. The purpose of the research is to study the accumulation and distribution of elements of hazard class I in plants of the genus Iris L. The research was carried out in 2020-2021 on the basis of the South-Ural Botanical Garden-Institute. Objects of study: soil of the site and plant organs (Iris orientalis, I. pseudacorus, I. sibirica, I. spuria subsp. carthaliniae). The elemental composition was determined by the atomic absorption method with electrothermal atomization. The distribution of pollutants was evaluated using the biological absorption coefficient (BAC), total cumulation in vegetative and generative, as well as underground and aboveground organs. It is shown that the content of mobile forms of HM and metalloids in the soil does not exceed the maximum allowable concentrations (MAC) and averages: Cd – 0.03, As – 0.59, Pb – 0.48 mg/kg. It was found that the distribution of cadmium in organs depends on the species: both basipetal (I. orientalis – 0.05 mg/kg) and acropetal accumulation of the element (I. spuria subsp. carthaliniae – 0.05 mg/kg) are possible. Accumulation in above-ground organs exceeds cumulation in roots from 1.4 to 7.5 times. It was determined that the values of CBA for cadmium differ from 0.27 to 1.56. It was shown that the roots of I. orientalis, I. pseudacorus, I. spuria subsp. carthaliniae perform a barrier function and accumulate arsenic in amounts exceeding the MPC (0.67-0.85 mg/kg). The root system of I. sibirica does not prevent the entry of the toxicant concentrated in the generative organs at a concentration exceeding the MPC (0.61-0.78 mg/kg). It was determined that the CBA of arsenic in the leaves of all species is <1. Lead uptake is species-independent, as evidenced by close total elemental values, similar organ distribution, and consistently high MAC. A predominantly above-ground concentration of the pollutant was revealed (3.4-5.1). The result of the regression analysis showed that the content of the mobile form of lead in the soil does not affect its accumulation in the leaves.