bluuebunny/crossref_metadata_2025 huggingface dataset:
Growth of black arsenic phosphorus thin films and its application for field-effect transistors
Authors: Izquierdo Nezhueyotl , Myers Jason C , Golani Prafful , De Los Santos Adonica , Seaton Nicholas C A , Koester Steven J , Campbell Stephen A
Published: April 2021

Black arsenic phosphorus single crystals were grown using a short-way transport technique resulting in crystals up to 12 × 110

μ
m

and ranging from 200 nm to 2

μ
m

thick. The reaction conditions require tin, tin (IV) iodide, gray arsenic, and red phosphorus placed in an evacuated quartz ampule and ramped up to a maximum temperature of 630 °C. The crystal structure and elemental composition were characterized using Raman spectroscopy, x-ray diffraction, and x-ray photoelectron spectroscopy, cross-sectional transmission microscopy, and electron backscatter diffraction. The data provides valuable insight into the growth mechanism. A previously developed b-P thin film growth technique can be adapted to b-AsP film growth with slight modifications to the reaction duration and reactant mass ratios. Devices fabricated from exfoliated bulk-b-AsP grown in the same reaction condition as the thin film growth process are characterized, showing an on-off current ratio of 102, a threshold voltage of −60 V, and a peak field-effect hole mobility of 23 cm2 V−1 s−1 at V
d = −0.9 V and V
g = −60 V.
Anatomy-aided deep learning for medical image segmentation: a review
Authors: Liu Lu , Wolterink Jelmer M , Brune Christoph , Veldhuis Raymond N J
Published: April 2021

Deep learning (DL) has become widely used for medical image segmentation in recent years. However, despite these advances, there are still problems for which DL-based segmentation fails. Recently, some DL approaches had a breakthrough by using anatomical information which is the crucial cue for manual segmentation. In this paper, we provide a review of anatomy-aided DL for medical image segmentation which covers systematically summarized anatomical information categories and corresponding representation methods. We address known and potentially solvable challenges in anatomy-aided DL and present a categorized methodology overview on using anatomical information with DL from over 70 papers. Finally, we discuss the strengths and limitations of the current anatomy-aided DL approaches and suggest potential future work.
Three-fluid model of the plasma–sheath region for a planar probe immersed in an active oxygen discharge. Validity of the Boltzmann relation
Authors: Morales Crespo R , Muñoz-Serrano E , Tejero-del-Caz A , Casado E
Published: April 2021

This paper studies the effect of the generation-loss processes in the plasma–sheath region close to a probe immersed in an oxygen discharge considering a three-fluid model for the charged species. A significant deviation from the Boltzmann relationship is obtained for the negative ion density when different values of the electron temperature, the negative ion temperature, the negative ion concentration, and the collision mean free path are considered.
Highly sensitive and stretchable strain sensor based on self-aligned and periodic cracking of wavy metal nanowire/elastomer composite film
Authors: Ha Sung-Hun , Kim Jong-Man
Published: April 2021

In this work, we present a new class of stretchable strain sensor employing a wavy metal nanowire (mNW)/elastomer composite film. Stretching-induced strain is predominantly concentrated in the valley regions of the wavy composite film following thermal annealing, and self-aligned and periodic mechanical cracks are induced by the strain concentration effect therein. The strain-dependent opening-and-closing process of the cracks supported by the mNW percolation network allows the sensor to exhibit large stretchability (160%) and high mechanosensitivity (gauge factor ≈874.1 at 110%–160% strain) simultaneously. Significant hysteresis is not observed, even when subjected to repeated stretching cycles. The wavy strain sensor is also demonstrated as a motion detector to recognize finger joint motions of a wooden hand model in real time.
Switching plasmonic resonance in multi-gap infrared metasurface absorber using vanadium dioxide patches
Authors: Negm Ayman , Bakr Mohamed , Howlader Matiar , Ali Shirook
Published: April 2021

Reconfigurable metasurface absorbers enable collecting or emitting radiation within selected frequency bands. It is thus necessary to decipher such behavior for many applications, including plasmonic energy harvesting, radiative cooling and thermal emitters. In this article, we propose a compact reconfigurable vanadium dioxide (VO2)-based metasurface absorber/emitter to demonstrate switching between dual and single-band absorption modes in the mid-infrared regime. The unit cell of the design employs a four-split gold circular ring resonator with gaps filled with VO2 patches. The phase-transition property of VO2 between semiconductor and metallic states is used to control the mode of operation of the metasurface absorber. When VO2 is in the semiconductor state, a dual-band absorption at 6 μm and 10.6 μm is obtained. When it attains a metallic state, the metasurface exhibits a single-band absorption at 8.25 μm. To achieve the maximum absorption efficiency in both single and dual-band modes, adaptive wind-driven optimization was employed as a global optimization technique. The proposed absorber provides polarization-independent behavior for both Transverse Electric and Transverse Magnetic polarizations. Moreover, the proposed design shows above 80% absorptance for incidence angle up to 45° for the dual-band mode, and up to 35° for the single-band mode. When operating the absorber as a tunable emitter, a switching of 79% in emissivity is achieved at 8.25 μm. These favorable findings may facilitate the development of important devices for temperature regulation, smart windows, and thermal imaging.
Constructing the weighting coefficients for the RBF-Hermite FD scheme under the multiquadric function on irregular meshes
Authors: Bin Jebreen Haifa , Tchier Fairouz
Published: April 2021

It is well known that the order of finite difference estimates on nonuniform grids reduce dramatically, particularly when higher order derivatives are required. This paper contributes how an optimization of the order of approximation formulas can be investigated and done on such grids for a sufficiently smooth function. To generalize the idea as well as get the optimized orders, the notion of radial basis function—Hermite finite difference (RBF–HFD) approach is used. The new weighting coefficients are worked out and proved to possess higher convergence rates. Several tests are also given to demonstrate the theoretical discussions.
Velocity-dependent J-factors for annihilation radiation from cosmological simulations
Authors: Board Erin , Bozorgnia Nassim , Strigari Louis E. , Grand Robert J.J. , Fattahi Azadeh , Frenk Carlos S. , Marinacci Federico , Navarro Julio F. , Oman Kyle A.
Published: April 2021

We determine the dark matter pair-wise relative velocity distribution in a set of Milky Way-like halos in the Auriga and APOSTLE simulations. Focusing on the smooth halo component, the relative velocity distribution is well-described by a Maxwell-Boltzmann distribution over nearly all radii in the halo. We explore the implications for velocity-dependent dark matter annihilation, focusing on four models which scale as different powers of the relative velocity: Sommerfeld, s-wave, p-wave, and d-wave models. We show that the J-factors scale as the moments of the relative velocity distribution, and that the halo-to-halo scatter is largest for d-wave, and smallest for Sommerfeld models. The J-factor is strongly correlated with the dark matter density in the halo, and is very weakly correlated with the velocity dispersion. This implies that if the dark matter density in the Milky Way can be robustly determined, one can accurately predict the dark matter annihilation signal, without the need to identify the dark matter velocity distribution in the Galaxy.
Reconstructing non-repeating radio pulses with Information Field Theory
Authors: Welling C. , Frank P. , Enßlin T. , Nelles A.
Published: April 2021

Particle showers in dielectric media produce radio signals
which are used for the detection of both ultra-high energy cosmic
rays and neutrinos with energies above a few PeV. The amplitude,
polarization, and spectrum of these short, broadband radio pulses
allow us to draw conclusions about the primary particles that caused
them, as well as the mechanics of shower development and radio
emission. However, confidently reconstructing the radio signals can
pose a challenge, as they are often obscured by background
noise. Information Field Theory offers a robust approach to this
challenge by using Bayesian inference to calculate the most likely
radio signal, given the recorded data. In this paper, we describe
the application of Information Field Theory to radio signals from
particle showers in both air and ice and demonstrate how accurately
pulse parameters can be obtained from noisy data.
Optical measurement of double-dot population using photon transmission via three coupled microresonators
Authors: Tsukanov A V , Kateev I Yu
Published: April 2021

A scheme for measuring the state of a charge qubit on a semiconductor single-electron double quantum dot (DQD) coupled to a photonic molecule (PM) consisting of three optical microresonators is proposed. The DQD that is the qubit plays the role of a nonlinear element whose electron state affects a PM response to an external laser field. Analysis of the spectroscopic response of the structure in the steady-state regime allows one to determine the state of the qubit. As an example, the spectrum of the PM formed by three GaAs microdisk resonators are calculated. The effect of various system parameters on the measuring contrast and the signal-to-noise ratio is studied. It is shown that this ratio can reach values of 15 000–20 000 for certain sets of parameters.
Stabilization of formamidinium lead iodide perovskite precursor solution for blade-coating efficient carbon electrode perovskite solar cells*
Authors: Zhan Yu , Chen Weijie , Yang Fu , Li Yaowen
Published: April 2021

Formamidinium lead triiodide (FAPbI3) is a research hotspot in perovskite photovoltaics due to its broad light absorption and proper thermal stability. However, quite a few researches focused on the stability of the FAPbI3perovskite precursor solutions. Besides, the most efficient FAPbI3layers are prepared by the spin-coating method, which is limited to the size of the device. Herein, the stability of FAPbI3perovskite solution with methylammonium chloride (MACl) or cesium chloride (CsCl) additive is studied for preparing perovskite film through an upscalable blade-coating method. Each additive works well for achieving a high-quality FAPbI3film, resulting in efficient carbon electrode perovskite solar cells (pero-SCs) in the ambient condition. However, the perovskite solution with MACl additive shows poor aging stability that noα-FAPbI3phase is observed when the solution is aged over one week. While the perovskite solution with CsCl additive shows promising aging stability that it still forms high-quality pureα-FAPbI3perovskite film even the solution is aged over one month. During the solution aging process, the MACl could be decomposed into methylamine which will form some unfavored intermediated phase inducingδ-phase FAPbI3. Whereas, replacing MACl with CsCl could effectively solve this issue. Our founding shows that there is a great need to develop a non-MACl FAPbI3perovskite precursor solution for cost-effective preparation of pero-SCs.
Collective excitations and quantum size effects on the surfaces of Pb(111) films: An experimental study*
Authors: Wang Yade , Lin Zijian , Xue Siwei , Li Jiade , Li Yi , Zhu Xuetao , Guo Jiandong
Published: April 2021

Pb(111) film is a special system that exhibits strong quantum size effects in many electronic properties. The collective excitations, i.e., plasmons, in Pb(111) films are also expected to show signatures of the quantum size effect. Here, using high-resolution electron energy loss spectroscopy, we measured the plasmons on the surface of Pb(111) films with different film thicknesses and analyzed the plasmon dispersions. One surface plasmon branch exhibits prominent damping in the small momentum range, which can be attributed to the interaction between the top and bottom interfaces of the Pb(111) films. With the film thickness increasing, the critical momentum characterizing the damping in Pb(111) films decays not only much slower in Pb(111) films than in other metal films, and even in films with the thickness up to 40 monolayers the damping still exists. The slow decay of the surface plasmon damping, manifesting the strong quantum size effect in Pb(111) films, might be related to the strong nesting of the Fermi surface along the (111) direction.
Tuning charge and orbital ordering in DyNiO3 by biaxial strain*
Authors: Jiang Litong , Jin Kuijuan , Ren Wenning , Yang Guozhen
Published: April 2021

The first-principles calculations were used to explore the tunable electronic structure in DyNiO3 (DNO) under the effects of the biaxial compressive and tensile strains. We explored how the biaxial strain tunes theorbital hybridization and influences the charge and orbital ordering states. We found that breathing mode and Jahn–Teller distortion play a primary role in charge ordering state and orbital ordering state, respectively. Additionally, the calculated results revealed that the biaxial strain has the ability to manipulate the phase competition between the two states. A phase transition point has been found under tensile train. If the biaxial train is larger than the point, the system favors orbital ordering state. If the strain is smaller than the point, the system is in charge ordering state favorably.
Metal substrates-induced phase transformation of monolayer transition metal dichalcogenides for hydrogen evolution catalysis*
Authors: Wang Zhe , Zhu Wenguang
Published: April 2021

Monolayer transition metal dichalcogenides can normally exist in several structural polymorphs with distinct electrical, optical, and catalytic properties. Effective control of the relative stability and transformation of different phases in these materials is thus of critical importance for applications. Using density functional theory calculations, we investigate the effects of low-work-function metal substrates including Ti, Zr, and Hf on the structural, electronic, and catalytic properties of monolayer MoS2 and WS2. The results indicate that such substrates not only convert the energetically stable structure from the 1H phase to the 1T′/1T phase, but also significantly reduce the kinetic barriers of the phase transformation. Furthermore, our calculations also indicate that the 1T′ phase of MoS2 with Zr or Hf substrate is a potential catalyst for the hydrogen evolution reaction.
Quantum storage of single photons with unknown arrival time and pulse shapes*
Authors: You Yu , Lin Gong-Wei , Feng Ling-Juan , Niu Yue-Ping , Gong Shang-Qing
Published: April 2021

We present a scheme for the quantum storage of single photons using electromagnetically induced transparency (EIT) in a low-finesse optical cavity, assisted by state-selected spontaneous atomic emission. Mediated by the dark mode of cavity EIT, the destructive quantum interference between the cavity input–output channel and state-selected atomic spontaneous emission leads to strong absorption of single photons with unknown arrival time and pulse shapes. We discuss the application of this phenomenon to photon counting using stored light.
Dynamical analysis, circuit realization, and application in pseudorandom number generators of a fractional-order laser chaotic system*
Authors: Ma Chenguang , Banerjee Santo , Xiong Li , Liu Tianming , Han Xintong , Mou Jun
Published: April 2021

A new five-dimensional fractional-order laser chaotic system (FOLCS) is constructed by incorporating complex variables and fractional calculus into a Lorentz–Haken-type laser system. Dynamical behavior of the system, circuit realization and application in pseudorandom number generators are studied. Many types of multi-stable states are discovered in the system. Interestingly, there are two types of state transition phenomena in the system, one is the chaotic state degenerates to a periodical state, and the other is the intermittent chaotic oscillation. In addition, the complexity of the system when two parameters change simultaneously is measured by the spectral entropy algorithm. Moreover, a digital circuit is design and the chaotic oscillation behaviors of the system are verified on this circuit. Finally, a pseudo-random sequence generator is designed using the FOLCS, and the statistical characteristics of the generated pseudo-random sequence are tested with the NIST-800-22. This study enriches the research on the dynamics and applications of FOLCS.
Cobalt anchored CN sheet boosts the performance of electrochemical CO oxidation*
Authors: Liu Xu , Huang Jun-Chao , Duan Xiang-Mei
Published: April 2021

Single-atom catalysts (SACs) have attracted great interest due to their significant roles played in applications of environmental protection, energy conversion, energy storage, and so on. Using first-principles calculations with dispersion-correction, we investigated the structural stability and catalytic activity of Co implanted CN sheet towards CO oxidation. The adsorption energy of CO and O2 on the catalysts Co@CN and 2Co@CN are close, thus preventing CO poisoning. Among three possible CO oxidation mechanisms, termolecular Eley-Rideal is the most appropriate reaction path, and the corresponding rate-limiting reaction barriers of the two systems are 0.42 eV and 0.38 eV, respectively.
Spectral study of V565 Mon: probable FU Ori-like or chemically peculiar star
Authors: Andreasyan Hasmik
Published: April 2021

We present a detailed spectroscopic study of pre-main sequence star V565 Mon, which is the illuminating star of the Parsamian 17 cometary nebula. Observations were performed with the 2.6 m telescope in Byurakan Astrophysical Observatory on 2018 February 15. Radial velocities and equivalent widths of the most prominent lines of V565 Mon are presented. We build the spectral energy distribution and estimate the main parameters of the star, for example the obtained bolometric luminosity of V565 Mon is L

V565 ≈ 130 L
⊙. Considering all features of V565 Mon, we come to the conclusion that this young intermediate-mass star belongs to some intermediate class between T Tau and HAeBe stars. Very unusual for a young star is the presence of strong absorption Ba II lines in the spectrum. Possible explanations on this issue are discussed. Hence, we think that V565 Mon is a unique example, which can help to understand some open questions involved in the problem of nucleosynthesis in young stars.
A broad absorption line outflow associated with the broad emission line region in the quasar SDSS J075133.35+134548.3
Authors: Liu Bo , Zhou Hong-Yan , Shu Xin-Wen , Zhang Shao-Hua , Ji Tuo , Pan Xiang , Jiang Peng
Published: April 2021

We report on the discovery of unusual broad absorption lines (BALs) in the bright quasar SDSS J075133.35+134548.3 at z ∼ 1, using archival and newly obtained optical and NIR spectroscopic data. The BALs are detected reliably in He i* λ3889, He i* λ10830 and tentatively in Al iii, Mg ii. These BALs show complex velocity structures consisting of two major components: a high-velocity component (HV), with a blueshifted velocity range of Δv
HV ∼ −9300 − −3500 km s−1, which can be reliably detected in He i* λ10830, and tentatively in Al iii and Mg ii, whereas it is undetectable in He i* λ3889 and a low-velocity component (LV), with Δ v
LV ∼ −3500 − −1800 km s−1, is only detected in He i* and He i* λ10830. With the BALs from different ions, the HV outflowing gas can be constrained to have a density of n
H ∼1010.3–1011.4 cm−3, a column density of N
H ∼ 1021 cm−2 and an ionization parameter of U ∼10−1.83–10−1.72; inferring a distance of R
HV∼0.5 pc from the central continuum source with a monochromatic luminosity λ
Lλ
(5100) = 7.0×1045 erg s−1 at 5100 Å. This distance is remarkably similar to that of the normal broad line region (BLR) estimated from reverberation experiments, suggesting association of the BLR and the HV BAL outflowing gas. Interestingly, a blueshifted component is also detected in Al iii and Mg ii broad emission lines (BELs), and the Al iii/Mg ii of such a BEL component can be reproduced by the physical parameters inferred from the HV BAL gas. The LV BAL gas likely has a larger column density, a higher ionization level and hence a smaller distance than the HV BAL gas. Further spectroscopy with a high S/N ratio and broader wavelength coverage is needed to confirm this to shed new light on the possible connection between BALs and BELs.
A star-based method for precise wavelength calibration of the Chinese Space Station Telescope (CSST) slitless spectroscopic survey
Authors: Yuan Hai-Bo , Deng Ding-Shan , Sun Yang
Published: April 2021

The Chinese Space Station Telescope (CSST) spectroscopic survey aims to deliver high-quality low-resolution (R > 200) slitless spectra for hundreds of millions of targets down to a limiting magnitude of about 21 mag, distributed within a large survey area (17 500 deg2) and covering a wide wavelength range (255–1000 nm by three bands GU, GV, and GI). As slitless spectroscopy precludes the usage of wavelength calibration lamps, wavelength calibration is one of the most challenging issues in the reduction of slitless spectra, yet it plays a key role in measuring precise radial velocities of stars and redshifts of galaxies. In this work, we propose a star-based method that can monitor and correct for possible errors in the CSST wavelength calibration using normal scientific observations, taking advantage of the facts that (i) there are about ten million stars with reliable radial velocities now available thanks to spectroscopic surveys like LAMOST, (ii) the large field of view of CSST enables efficient observations of such stars in a short period of time, and (iii) radial velocities of such stars can be reliably measured using only a narrow segment of CSST spectra. We demonstrate that it is possible to achieve a wavelength calibration precision of a few km s−1 for the GU band, and about 10 to 20 km s−1 for the GV and GI bands, with only a few hundred velocity standard stars. Implementations of the method to other surveys are also discussed.
On the radial velocity calibrations in the LAMOST medium-resolution spectroscopic survey of nebulae
Authors: Ren Juan-Juan , Wu Hong , Wu Chao-Jian , Zhang Wei , Chen Jian-Jun , Hsia Chih-Hao , Yang Fan , Liu Chao , Shi Jian-Rong , Wu Yu-Zhong , Zhu Hui , Li Bin , Bai Zhong-Rui , Tian Hao , Hou Yong-Hui
Published: April 2021

Accurate radial velocity determinations of optical emission lines (i.e., [Nii] λλ 6548, 6584, Hα and [S ii] λλ 6717, 6731) are very important for investigating the kinematic and dynamic properties of nebulae. The second stage survey program of Large sky Area Multi-Object fiber Spectroscopic Telescope (LAMOST) has started a sub-survey of nebulae (MRS-N) which will spectroscopically observe the optical emission lines of a large sample of nebulae near the Galactic plane. Until now, 15 MRS-N plates have been observed from September 2017 to June 2019. Based on fitting the sky emission lines in the red band spectra of MRS-N, we investigate the precision of wavelength calibration and find there are systematic deviations of radial velocities (RVs) from ∼ 0.2 to 4 km s−1 for different plates. Especially for the plates obtained in March 2018, the systematic deviations of RVs can be as large as ∼ 4 km s−1, which then go down to ∼ 0.2 – 0.5 km s−1 at the end of 2018 and January 2019. An RV calibration function is proposed for these MRS-N plates, which can simultaneously and successfully calibrate the systematic deviations and improve the precision of RVs.
Investigation of the shortest period Am type eclipsing binary TYC 6408–989–1
Authors: Tian Xiao-Man
Published: April 2021

The first BV bands photometric observations and the low-resolution spectrum of the shortest period Am type eclipsing binary TYC 6408–989–1 have been obtained. The stellar atmospheric parameters of the primary star were obtained through the spectral fitting as follows: T
eff = 6990 ± 117 K, log g = 4.25 ± 0.26 cm s−2, [Fe/H] = −0.45 ± 0.03 dex. The original spectra obtained by European Southern Observatory (ESO) were processed with an IRAF package by us. Based on the ESO blue-violet spectra, TYC 6408–989–1 was concluded as a marginal Am (Am:) star with a spectral type of kA3hF1mA5 IV-V identified through the MKCLASS program. The observed light curves were analyzed through the Wilson-Devinney code. The final photometric solutions show that TYC 6408–989–1 is a marginal contact binary with a low mass ratio (q = 0.27). The temperature of the secondary component derived through the light curve analysis is significantly higher than main sequence stars. In addition, TYC 6408–989–1 is a poor thermal contact binary. The temperature differences between the two components is about 1800 K. TYC 6408–989–1 should be located in the oscillation stage predicted by the thermal relaxation oscillations theory (TRO) and will evolve into the shallow contact stage eventually. The very short period (less than one day), marginal Am peculiarity and quite large rotational velocity (v sin i ≃ 160 km s−1) make TYC 6408–989–1 become a challenge to the cut-off of rotation velocities and periods of Am stars. We have collected the well known eclipsing Am binaries with absolute parameters from the literature.
Adaptive scale model reconstruction for radio synthesis imaging
Authors: Zhang Li , Mi Li-Gong , Xu Long , Zhang Ming , Li Dan-Yang , Liu Xiang , Wang Feng , Xiao Yi-Fan , Wu Zhong-Zu
Published: April 2021

A sky model from CLEAN deconvolution is a particularly effective high dynamic range reconstruction in radio astronomy, which can effectively model the sky and remove the sidelobes of the point spread function (PSF) caused by incomplete sampling in the spatial frequency domain. Compared to scale-free and multi-scale sky models, adaptive-scale sky modeling, which can model both compact and diffuse features, has been proven to have better sky modeling capabilities in narrowband simulated data, especially for large-scale features in high-sensitivity observations which are exactly one of the challenges of data processing for the Square Kilometre Array (SKA). However, adaptive scale CLEAN algorithms have not been verified by real observation data and allow negative components in the model. In this paper, we propose an adaptive scale model algorithm with non-negative constraint and wideband imaging capacities, and it is applied to simulated SKA data and real observation data from the Karl G. Jansky Very Large Array (JVLA), an SKA precursor. Experiments show that the new algorithm can reconstruct more physical models with rich details. This work is a step forward for future SKA image reconstruction and developing SKA imaging pipelines.
An investigation of flare emissions at multiple wavelengths
Authors: Li Dong , Warmuth Alexander , Lu Lei , Ning Zongjun
Published: April 2021

We report multi-wavelength observations of four solar flares on 2014 July 07. We firstly select these flares according to the soft X-ray (SXR) and extreme ultraviolet (EUV) emissions recorded by the Extreme Ultraviolet Variability Experiment and Geostationary Orbiting Environmental Satellites. Then their locations and geometries are identified from the full-disk images measured by the Atmospheric Imaging Assembly (AIA), and the time delays among the light curves in different channels are identified. The electron number densities are estimated using the differential emission measure method. We find that three of four flares show strong emissions in SXR channels and high temperature (>6 MK) EUV wavelengths during the impulsive phase, i.e., AIA 131 Å and 94 Å, and then they emit peak radiation subsequently in the middle temperature (∼0.6−3 MK) EUV channels. Moreover, they last for a long time and have smaller electron densities, which are probably driven by the interaction of hot diffuse flare loops. Only one flare emits radiation at almost the same time in all the observed wavelengths, lasts for a relatively short time, and has a larger electron density. It is also accompanied by a type III radio burst. The bright emission at the EUV channel could be corresponding to the associated erupting filament.
Longitudinal analysis of local field potentials recorded from directional deep brain stimulation lead implants in the subthalamic nucleus
Authors: Brinda AnneMarie K , Doyle Alex M , Blumenfeld Madeline , Krieg Jordan , Alisch Joseph S R , Spencer Chelsea , Lecy Emily , Wilmerding Lucius K , DeNicola Adele , Johnson Luke A , Vitek Jerrold L , Johnson Matthew D
Published: April 2021

Objective. The electrode–tissue interface surrounding a deep brain stimulation (DBS) lead is known to be highly dynamic following implantation, which may have implications on the interpretation of intraoperatively recorded local field potentials (LFPs). We characterized beta-band LFP dynamics following implantation of a directional DBS lead in the sensorimotor subthalamic nucleus (STN), which is a primary target for treating Parkinson’s disease. Approach. Directional STN-DBS leads were implanted in four healthy, non-human primates. LFPs were recorded over two weeks and again 1–4 months after implantation. Impedance was measured for two weeks post-implant without stimulation to compare the reactive tissue response to changes in LFP oscillations. Beta-band (12–30 Hz) peak power was calculated from the LFP power spectra using both common average referencing (CAR) and intra-row bipolar referencing (IRBR). Results. Resting-state LFPs in two of four subjects revealed a steady increase of beta power over the initial two weeks post-implant whereas the other two subjects showed variable changes over time. Beta power variance across days was significantly larger in the first two weeks compared to 1–4 months post-implant in all three long-term subjects. Further, spatial maps of beta power several hours after implantation did not correlate with those measured two weeks or 1–4 months post-implant. CAR and IRBR beta power correlated across short- and long-term time points. However, depending on the time period, subjects showed a significant bias towards larger beta power using one referencing scheme over the other. Lastly, electrode–tissue impedance increased over the two weeks post-implant but showed no significant correlation to beta power. Significance. These results suggest that beta power in the STN may undergo significant changes following DBS lead implantation. DBS lead diameter and electrode recording configurations can affect the post-implant interpretation of oscillatory features. Such insights will be important for extrapolating results from intraoperative and externalized LFP recordings.
Transcription factor binding site detection using convolutional neural networks with a functional group-based data representation
Authors: Pap Gergely , Zoltán Györgypál , Ádám Krisztián , Tóth László , Hegedűs Zoltán
Published: April 2021

Transcription factors (TFs) play an essential role in molecular biology by regulating gene expression. The binding sites of TFs can vary by a large amount and the numerous possible binding locations make their detection a challenging issue. Recently, several machine learning approaches using nucleotide sequence data were applied to classify DNA sequences regarding Transcription Factor Binding Sites (TFBS). We propose a novel training strategy without the traditional 1D nucleotide-based DNA sequence representation by instead using a 2D topological matrix of sub-nucleotide chemical functional groups substantially defining the protein binding ability of DNA fragments. We train convolutional neural networks using this novel Functional Group DNA Representation (FGDR) to solve a TFBS classification task. We compare our results with the efficiency of previous nucleotide-based training approaches and show that learning from an FGDR data sequence has several benefits regarding TFBS classification. Moreover, we reason that learning deep neural networks from the FGDR representation produces competitive results while only introducing a pre-processing conversion step. Finally, we show that employing an ensemble of models from the nucleotide and FGDR representations for network training results in higher classification performance than any of the single input approaches.
Research on the Mechanism of Multi-resource Mapping Matching and Transmission of Road System Based on Meme Theory
Authors: Mao Chengyuan , Wang Qin , Feng Kangli , Yang Shengde , Bao Lewen
Published: April 2021

Because of the inefficiency and unscientific use of existing urban road traffic facilities, this paper sorts out the problems and optimization methods of domestic and foreign road traffic system, establishes the “set of problems” and “set of countermeasures”. Put forward the replication factor and mutation factor of optimization methods based on Meme theory, carry out the matching and transmission of multiple resource mapping, and feedback the implementation effect of the plan through simulation application and evaluation, so as to improve the mechanism of multi-resource mapping matching and transmission model. Cases study proved that Meme theory can be better applied to the automatic matching and selection of urban road traffic system optimization schemes and guided the optimization of urban road traffic systems more efficiently.
Automatic Finite Element Mesh Generation on 3D Surfaces Based on STEP
Authors: Jia Hong
Published: April 2021

Computer Aided Engineering (CAE) have a vital value in die and mould manufacturing. For the purpose of enhancing the modelling ability of the existing CAE analysis system and improving the mesh generation quality and working efficiency, a system for automatic finite element mesh generation on 3D surfaces is designed and implemented. Applying the neutral mechanism for product information sharing provided by STEP, product model import and reconstruction process is first implemented. And then product model information extraction module is developed aims at preparing geometrical and topological information for finite element mesh generation. An improved strategy for automatic triangular mesh generation over 3D surface is adopted to realize the mesh generation of the system. Implemented results indicate that the presented system helps to improve the mesh quality and at the same time increase the process efficiency and reduce the time cost.
Features of the deposition of photonic crystal films of polystyrene and silica
Authors: Panfilova E.V. , Shramko D.Y. , Ibragimov A.R. , Mozer K.V.
Published: April 2021

The paper presents the results of research in the field of deposition technology for self-organizing colloidal films. Such structures can be used in the manufacture of controlled photonic crystal devices. Therefore, it is important to determine methods and modes of obtaining high-quality ordered periodic opal structures. We compare the methods of vertical deposition and electrophoresis and discuss the features of their application in the deposition of films formed from colloidal particles of polystyrene and silica. We have found that vertical film deposition when the substrate is pulled out of the colloidal suspension is the most technologically convenient and suitable for both materials. The electrophoresis method is more difficult to implement, but it allows you to control the deposition process in dynamics. n this article, we present the identified rational modes of obtaining photonic crystal films by both methods.
Magneto-luminescent nanostructures for biomedicine
Authors: Matiushkina A A , Bazhenova A S , Litvinov I K , Belyaeva T N , Kornilova E S , Dubavik A Y , Orlova A O
Published: April 2021

Magneto-luminescent nanosystems can be widely applied in biomedicine, namely for disease theranostics, early tumor imaging, and as drug delivery and hyperthermia agents. The creation of such systems using superparamagnetic iron oxide nanoparticles (SPIONs) and semiconductor quantum dots (QDs) approach is popular, since SPIONs are characterized by excellent magnetic properties and zero coercive force, and QDs have advantages over the majority of organic phosphors. In this work, the alloyed (CdxZn1-xSeyS1-y)/ZnS quantum dots are used to reduce the probability of Förster Resonance Energy Transfer or electron transfer, that quench QD photoluminescence, due to a thick gradient semiconductor shell. Moreover, Magnetic Circular Dichroism (MCD) spectroscopy has been successfully applied as a method for monitoring both magnetic properties and colloidal stability of magnetic nanoparticles in a solution, which is crucial for their biomedical applications. The simplicity of SPION/QDs nanostructure formation due to the sequential addition of a SPION solution to a QD solution is a major advantage of this approach. It was demonstrated that these SPION/QDs nanostructures are stable, can be efficiently absorbed by the HeLa cells, and do not show high cytotoxicity at low concentrations (up to 25 nM).
Application of scanning probe energy loss spectroscopy to SERS-active metal nanostructures
Authors: Beshr M , Amarandei G , Meade A D , Palmer R E , Murphy S
Published: April 2021

Surface-enhanced Raman spectroscopy (SERS) relies on adsorbing target molecules onto metal nanostructures where the light can resonantly couple with localised surface plasmon resonances. These plasmons can be tuned by changing the nanostructure size, shape, spacing and composition, but this is a complex process. Therefore, having an experimental method that can directly map the plasmons would be extremely useful for developing SERS-active substrates. This paper investigates the possibility of applying a novel scanning probe method, scanning probe energy loss spectroscopy, to map the plasmonic behaviour of SERS-active metal nanostructures in order to optimise their enhancement factor and reproducibility.
Investigation of the influence of tungsten carbide nanopowder WC and the mixture of tungsten carbides and titanium carbides (WC, TiC) on the change of concrete performance properties
Authors: Gavrish V. , Chayka T. , Baranov G. , Oleynik A.Y. , Shagova Y.O.
Published: April 2021

The paper deals with the possibility of changing the operational properties of concrete (strength, water absorption, corrosion resistance) by adding WC tungsten carbide nanopowders and a mixture of WC tungsten carbide and TiC titanium carbides obtained from hard-alloy waste to the initial composition. As a result of the research, the concentrations of nanopowders were determined, at which the maximum change in strength is observed. Changes in water absorption at different time intervals and corrosion resistance of concrete samples at optimal concentrations were studied. The paper shows a positive effect on the performance of concrete mixture of WC, WC and TiC nanomodifiers.
Influence of tungsten nanopowders W, tungsten oxide WO3, tungsten carbide WC on changing radio protective properties of polymers
Authors: Gavrish B , Chaika T , Cherkashina N , Frolova M
Published: April 2021

The paper considers the possibility of improving radio protective properties of polymers by modifying with nanopowders: tungsten W, tungsten oxide WO3, tungsten carbide WC, obtained from hard-alloy waste. The study determined the coefficients of linear attenuation of gamma radiation in the energy range of 59.93 keV…1408 keV at various concentrations of nanopowders 20…80% of the mass of the material, with a step of 20%. The comparative characteristic of the obtained data is given. The developed composite materials can be used in the systems of passive protection, dosimetry, space technology, as well as greatly facilitate the weight of various structural products.
Investigation of the effect of tungsten carbide nanopowder additives on the strength properties of fiberglass, based on LAVESAN glass fabric and EPR 320 epoxy resin
Authors: Gavrish V. , Chayka T. , Baranov G. , Oleynik A.Y.
Published: April 2021

The paper presents the results of tests for modulus of elasticity and tensile strength of fiberglass samples consisting of glass fiber Lavesan (Italy) and epoxy resin binder EPR 320 with hardener EPH 162, modified with WC tungsten carbide nanopowder, obtained from carbide waste. The positive effect of WC nanopowder on tensile strength and modulus of elasticity is shown. With the addition of nanoadditives in the mass concentration of 1 … 4% of the resin mass, the increase in tensile strength was more than 1.5 … 2.5 times, with no significant change in material elasticity.
Relevance Feedback For Image Retrieval Using Transfer Learning and Improved MQHOA
Authors: Wang Huaqiu , Liu Qian
Published: April 2021

Image retrieval is a challenging technology in multimedia applications where meeting the users’ subjective retrieval needs while achieving high retrieval performance is insufficient for existing methods. In this work, a related feedback image retrieval algorithm based on deep learning and optimization algorithm (CAMQHOA-RF) is proposed. Transfer learning based on the deep convolutional neural network is applied to extract deeper image features to reduce the semantic gap. The multi-scale quantum harmonic oscillator algorithm improved by the idea of “aggregation” is introduced to search the feature space effectively. The covariance matrix is used to strengthen the relationship between feature points at different scales to guide feature points to approach ideal query points faster. Moreover, the query point is reselected based on the feedback information to explore more potential users’ interest areas. Experiments have shown that compared with other algorithms, the proposed algorithm has fewer parameters that need to be set, but higher retrieval accuracy, faster retrieval speed, and stronger robustness are obtained, which can meet users better.
An Occlusion Handling Evaluation Criterion for Deep Learning Object Segmentation
Authors: Yang C , Chong P H J , Lam P
Published: April 2021

This paper introduces a novel evaluation criterion to occlusion handling for deep learning object segmentation. The occlusion is defined as objects blocking each other on an image. It affects deep learning object segmentation. More and more researches focus on occlusion handling for object segmentation. However, these researches do not clearly show the evaluation of their occlusion handling method, because there is no suitable evaluation criterion. Traditionally, people just use images results or use the entire object boundary accuracy to show the occlusion handling of their methods. Conversely, these ideas cannot give a numerical evaluation focusing on occlusion handling. This research reports an evaluation criterion to measure occlusion handling performance. This evaluation criterion uses the shortest distances between the pixels from the ground truth occlusion edges and the segmentation (result) shape. The shortest distances are segmentation errors. Then, the average value of these errors is the final parameter for occlusion handling evaluation criterion. The experiment uses a deep learning based segmentation model as an example. It shows that this criterion (or method) successfully measures the occlusion handling for deep learning based object segmentation.
Dynamic Degradation Quantification of Wind Turbine High Speed Shaft Bearing Based on Oscillation Based Sparsity Indices
Authors: Noman Khandaker , He Qingbo , Peng Zhike , Wang Dong
Published: April 2021

Wind turbine (WT) high speed shaft (HSS) bearing fault is important due to its significant number of failures. However, due to its non-stationary operation under varying speed condition, it is a challenging issue to quantify the degradation of WT-HSS bearing by conventional bearing indices. Aiming at the aforementioned issue, in this paper, tunable Q factor wavelet transform (TQWT) preprocessed sparsity indices are proposed to achieve the dynamic degradation quantification of WT-HSS bearing. Firstly, based on the ability of TQWT in dynamic extraction of fault component of a bearing signal under varying speed condition, low oscillatory transient signal component is separated from a noisy commercial WT-HSS bearing signal by continuously adjustable tunable Q factor wavelet transform (TQWT). Then, considering the suitability of sparsity indices in quantifying extracted fault component based on its energy concentration, four representative sparsity indices namely kurtosis, gini index, negative entropy and reciprocal smoothness index are used to quantify the separated low oscillatory signal component as a measure of WT-HSS bearing health. The proposed indices show a better performance than original sparsity indices and an improved version of sparsity indices based on adaptive weighted signal preprocessing in dynamic degradation quantification of a commercial WT-HSS bearing.
Automated Biometric Identification using Dorsal Hand Images and Convolutional Neural Networks
Authors: Mohaghegh Mahsa , Payne Ash
Published: April 2021

The identification of perpetrators, present in Child Sexual Abuse Imagery (CSAI), is a significant challenge due to the use of anonymisation techniques that mask their identities. Consequently, researchers have investigated the use of uncommon biometric identifiers such as knuckle patterns, palmprints and the dorsal side of the hand. This research proposes a Convolutional Neural Network (CNN) based, fully automated approach to biometric identification using dorsal hand images. The identification performance of three different CNN architectures, AlexNet, ResNet50 and ResNet152, is experimentally determined against two similar datasets, the 11k Hands and IITD dorsal hand databases. A transfer learning approach is used and the final output layers of the CNNs are modified to match the number of classes present in the datasets. The results showed that ResNet CNNs achieved identification accuracies greater than 99.9% on both datasets, whereas the AlexNet CNN achieved between 80.1% and 93.7%. These results demonstrate that it is feasible to use deep, off-the-shelf CNNs, such as ResNets, for automated biometric identification using dorsal hand images. This highlights the potential of using dorsal hand images to identify perpetrators of child sexual abuse from CSAI.
Research on HMM-based Exoskeleton Robot Falling Prediction Algorithm
Authors: Gao Leilei , Deng Keyong , Zhang Rui , Wang Meng , Wang Hao
Published: April 2021

Exoskeleton robot is essentially a wearable robot. In recent years, the research of exoskeleton robots has become a new hot spot, and has gradually been widely used in military, medical and civilian fields. However, the balance and safety issues of power-assisted exoskeleton robots need to be solved urgently. At present, although there are many researches on exoskeleton robots at home and abroad, the research on the falling problem of assisted lower limb exoskeleton robots is not in-depth. Existing studies on falls are mainly focused on the detection of falls, while the prediction of falls is relatively small, and these studies rely more on a single sensor, and its accuracy needs to be improved. In response to the status quo, This paper proposes a fall prediction algorithm based on HMM to study the fall behaviour of the exoskeleton human-machine system in advance, it provides a reference for the anti-fall measures of the exoskeleton robot and aims to effectively reduce the damage of the human-machine system.