bluuebunny/crossref_metadata_2025 huggingface dataset:
A fast Fourier transform based method to estimate frequency response mismatches in time interleaved systems
Authors: Yang Kuojun , Pan Zhixiang , Ye Peng , Shi Jiali , Zhao Yu , Meng Jie
Published: May 2021

Time interleaving (TI) technique is widely used in acquisition systems to improve the sampling rate. However, as a parallel sampling structure, it inevitably brings in channel mismatches, such as the offset mismatch, gain mismatch, and time mismatch. Moreover, the gain mismatch and time mismatch are frequency-dependent, which means that the gain mismatch and time mismatch will be different when the signal frequency changes. This is because the gain and time mismatches are the special circumstances of frequency response mismatches. In this paper, a frequency response mismatch estimation method in TI acquisition systems is proposed and analyzed. First, the two kinds of mismatch models are compared to find the relationship between frequency response mismatches and the gain and time mismatches. Then, a mismatch estimation method that can estimate mismatches when the analog bandwidth exceeds the sampling rate of a single channel in a time interleaving analog to digital converter is proposed. Sinusoids with different frequencies are utilized to convert the question of estimating frequency response mismatches to acquiring the mismatch coefficients at a series of frequency points. Furthermore, a semi-automatic estimation technique is proposed to reduce the operation time, and a 10 GSPS eight-channel TI system is introduced. Simulations show the accuracy and effectiveness of the proposed method. At last, the frequency response mismatches are calibrated by using the estimated parameters. The calibration improves the performance of an eight-channel TI system from the original spurious free dynamic range of 27.6639 to 56.7029 dB and signal-to-noise ratio of 25.5468 to 32.7667 dB. The calibration result demonstrates the usefulness of the proposed method.
Are phytotoxic effects of
Authors: Silva Eliane R. , Igartuburu José M. , Overbeck Gerhard E. , Soares Geraldo L. G. , Macías Francisco A.
Published: May 2021

We evaluated whether phytotoxic effects of the essential oil from Eucalyptus saligna Sm. leaf litter were related to its major compounds 1,8-cineole (eucalyptol) and α-pinene. Effects of the essential oil and its major compounds, combined and alone, were tested on germination and growth of the weed Eragrostis plana Ness. Volatile organic compounds (VOCs) emitted from the essential oil were determined in the airspace of Petri dishes during the experimental period. These volatile fractions were obtained by solid-phase microextraction (SPME) followed by gas-chromatography coupled to mass spectrometry (GC-MS). Effects of the oil and its major compounds were also assessed in aqueous solution on coleoptile growth of Triticum aestivum L. The essential oil showed the strongest phytotoxic effects on E. plana, followed by eucalyptol, eucalyptol + α-pinene, and α-pinene. A similar order of phytotoxicity was observed on coleoptile growth of T. aestivum. The proportion of oxygenated monoterpenes increased along the experimental period, mainly eucalyptol, and of monoterpene hydrocarbons diminished in the volatile fractions. We conclude that phytotoxicity of E. saligna leaf litter essential oil may be mainly related to eucalyptol and additive or synergistic effects of other minor compounds. Analysing VOCs emission is relevant to elucidate compounds involved in phytotoxicity of a plant species.
Parthenium hysterophorus (parthenium weed).
Authors: Weyl Philip , Vélez-Gavilán Jeanine , Shabbir Asad , Parker Chris
Published: May 2021

Parthenium hysterophorus is an annual herb that aggressively colonizes disturbed sites. It is considered as one of the '100 most invasive species in the world' by the IUCN (GISD, 2018). Native to the New World, it has been accidentally introduced into several countries and has become a serious agricultural and rangeland weed in parts of Australia, Asia, Africa and the Pacific Islands. It is reported as a major weed in field crops in more than 45 countries (Bajwa et al., 2016; Shabbir et al., 2019), with yield losses estimated in millions of dollars in Australia (Kaur et al., 2014). It grows on any type of soil and in a wide range of habitats. It affects the production of crops, animals, human and animal health, and biodiversity. Several characteristics, such as wide adaptability, photo- and thermo-insensitivity, lack of natural enemies in non-native regions, drought tolerance, strong competition and allelopathy, high seed production ability, longevity of seeds in soil seed banks, and small and light seeds that are capable of long distance travel via wind, water, birds, vehicles, farm machinery and other animal traffic, contribute to its rapid introduction world-wide, cutting across national boundaries and climate barriers (Kaur et al., 2014; Bajwa et al., 2016). The genetic diversity found among different populations and biotypes are also strongly contributing to its invasion success (Bajwa et al., 2018). The species is reported as invasive in various countries in Asia, Africa, and Oceania (Gnanavel, 2013; EPPO, 2018; GISD, 2018; PIER, 2018). In the Americas, it is reported as invasive in Cuba, and in Trinidad and Tobago. In Cuba it is considered as one of the most noxious species (Oviedo Prieto et al., 2012). Although listed as introduced by various sources it is also listed as native by others (USDA-ARS, 2018). In Trinidad and Tobago it is a predominant weed of industrial areas, crops, orchards, ornamentals and greenhouses (Bridgemohan et al., 2015).
Classification in sport: A question of fairness
Authors: Loland Sigmund
Published: May 2021

Competitor classification schemes have been a part of sport since its origins. Eligibility criteria have developed towards inclusion and increasing diversity. The pool of competitors has expanded from the ancient Olympic Games, eligible only to free Greek men, via nineteenth‐century English sport favouring primarily the upper class of so‐called gentlemen amateurs, to the current global and diverse pool of men, women, children, and able‐bodied as well as disabled persons. Hence, the challenge of sound classification schemes has increased. This article examines the principles of fair classification of athletes. With the help of normative theory as well as practical examples, a fair equality of opportunity principle for sport (FEOPs) is formulated. It is demonstrated how sound classification schemes combine the normative backing from FEOPs with relevant scientific insights. Current classification challenges and possibilities for change are discussed. It is suggested that in several sports, biological sex classes can be abandoned, and that in some sports, sex classes can be replaced by body size classes. It is argued, too, that sports in which body height exerts a significant and systematic impact on performance should classify accordingly. In the final part, classification is discussed in light of new techno‐scientific possibilities, among them the possibility of innovative performance‐enhancing prosthetics.
Partial range of motion training elicits favorable improvements in muscular adaptations when carried out at long muscle lengths
Authors: Pedrosa Gustavo F. , Lima Fernando V. , Schoenfeld Brad J. , Lacerda Lucas T. , Simões Marina G. , Pereira Mariano R. , Diniz Rodrigo C.R. , Chagas Mauro H.
Published: May 2021

The study compared changes in strength and regional muscle hypertrophy between different ranges of motion (ROM) in the knee extension exercise. Forty‐five untrained women were randomized to either a control group or to perform the exercise in one of the following 4 groups (0°=extended knee): Full ROM (FULLROM: 100°−30° of knee flexion); Initial Partial ROM (INITIALROM: 100°−65°); Final Partial ROM (FINALROM: 65°−30°); Varied ROM (VARROM: daily alternation between the ROM of INITIALROM and FINALROM). Pre‐ and post‐training assessments included one repetition maximum (1RM) testing in the ROM corresponding to the initial, final and full ROM, and measurement of cross‐sectional areas of the rectus femoris and vastus lateralis muscles at 40%, 50%, 60% and 70% of femur length in regard to regional muscle hypertrophy. Results showed that the INITIALROM group presented a greater relative increase than all groups at 70%, and at 50% and 60% the increases were greater than FINALROM, FULLROM, and non‐training control (CON) groups. Moreover, FINALROM group presented similar changes compared to the CON group at 60% and 70%. In regard to 1RM, FINALROM and INITIALROM groups presented greater relative increases at the ROM trained, and no group showed greater increases than VARROM or INITIALROM, regardless the ROM tested. In conclusion, partial ROM training in the initial phase of the knee extension exercise promoted greater relative hypertrophy in certain muscle regions than training in other ROM configurations, and no group promoted a greater 1RM increase than VARROM group, which showed similar 1RM increases in the different ROMs tested.
Validation of a novel technique with radioactive implanted ions for material recession rate estimate
Authors: Rapagnani D , De Cesare M , Buompane R , Del Vecchio A , Di Leva A , D’Onofrio A , Porzio G , Gialanella L
Published: May 2021

Durability tests of thermal protection system (TPS) materials for space vehicles is of paramount importance in developing TPS materials. The limits of the presently used techniques and the need for higher accuracy and precision demand new reliable and more sensitive measurement methods. In this paper we present the validation of a new on-line and non intrusive technique to estimate the TPS material recession rate which exploits the surface layer implantation of radioactive 7Be ions and the measurement of its characteristic γ-rays during the recession test.
In situ XPS studies of MoS2-based CO2 hydrogenation catalysts
Authors: Pacholik Gernot , Enzlberger Ludwig , Benzer Anna , Rameshan Raffael , Latschka Markus , Rameshan Christoph , Föttinger Karin
Published: May 2021

Various formulations of Co, Ni and K modified MoS2-based catalysts were synthesized hydrothermally and compared in their catalytic performance in CO2 hydrogenation at 21 bar and 220 °C–330 °C. The products were CO, CH4 and methanol. The addition of K reduced the selectivity to CH4 and moved the maximum of the methanol formation rate to a higher temperature. The materials were characterized by N2 physisorption, temperature programmed oxidation, temperature programmed reduction, and x-ray diffraction spectra (XRD). Under reducing conditions the catalysts were stable until 700 °C and under oxidizing conditions until 300 °C. XRD had shown mainly a MoS2 phase, as well as metal sulfide in the cobalt and nickel promoted catalysts. Different species of Mo and O were observed under reaction conditions by in situ x-ray photoelectron spectroscopy (XPS). When switching from H2 to CO2 + H2 an increase in the amount of oxygen, both lattice oxygen and surface adsorbates, was observed as a consequence of CO2 addition and H2O formation in the reaction. The amount of lattice oxygen correlates with the minor amount of Mo(VI) detected. Increasing reaction temperature and thus conversion led to an increase of the O 1s signals at 533 eV assigned to surface OH, formate and adsorbed H2O. XPS measurements in CO2 + H2 feed showed an effect of K addition on the adsorbate-related O 1s peak, which appeared at lower binding energy (532 eV) and was assigned to carbonates. This may indicate a different reaction mechanism in the presence of the promoter.
Characterization of a kHz sinusoidal Argon plasma jet impinging on water using Thomson scattering and fast imaging
Authors: Slikboer Elmar , L Walsh James
Published: May 2021

The electron dynamics in a stable and non-filamentary Argon plasma jet, generated using AC excitation at kHz frequencies and interacting with a liquid surface either at floating potential or electrically grounded were examined using laser Thomson scattering. In the case of a floating liquid, two discharge events were observed during each half-cycle of the applied sinusoidal voltage. In the grounded liquid case only one discharge event was observed, which occurred during the positive half period. Through spatio-temporal imaging of the discharge, its repetitive breakdown behavior was analyzed and divided into pre-, main-, and post-breakdown phases. The dynamics and presence of the various phases differed depending upon the grounding of the liquid. Thomson scattering measurements revealed maximum electron densities and temperatures of 6.0–6.3 × 1014 cm−3 and 3.1–3.3 eV for the floating liquid case and 1.1 × 1015 cm−3 and 4.3 eV in the grounded liquid case. Electron-driven reactions are the primary source of reactive chemical species in a plasma jet. Therefore, the electrical characteristics of the liquid sample can impact the fundamental physicochemical processes at play in the discharge, ultimately influencing its chemical composition.
Development of a highly sensitive sensor chip using optical diagnostic based on functionalized plasmonically active AuNPs
Authors: Thi Huong Vu , Thi Ta Hanh Kieu , Mai Ngoc Xuan Dat , Van Tran Thi Thanh , Khuyen Bui Xuan , Trinh Kieu The Loan , Lee Nae Yoon , Phan Bach Thang , Tran Nhu Hoa Thi
Published: May 2021

Measuring solution concentration plays an important role in chemical, biochemical, clinical diagnosis, environmental monitoring, and biological analyses. In this work, we develop a transmission-mode localized surface plasmon resonance sensor chip system and convenient method which is highly efficient, highly sensitive for detection sensing using multimode fiber. The plasmonically active sensor’s surface AuNPs with high-density NPs were decorated onto 1 cm sensing length of various clad-free fiber in the form of homogeneous monolayer utilizing a self-assembly process for immobilization of the target molecule. The carboxyl bond is formed through a functional reaction on the sensor head. Using the significance in the refractive index difference and numerical aperture, which is caused by a variation in the concentration of measuring bovine serum albumin (BSA) protein which can be accurately measured by the output signal. The refractive index variation of the medium analyte layer can be converted to signal output power change at the He–Ne wavelength of 632.8 nm. The sensor detection limit was estimated to be 0.075 ng ml−1 for BSA protein which shows high sensitivity compared to other types of label-free optical biosensors. This also leads to a possibility of finding the improvement in the sensitivity label-free biosensors. The conventional method should allow multimode fiber biosensors to become a possible replacement for conventional biosensing techniques based on fluorescence.
The classical Kelvin–Voigt problem for incompressible fluids with unknown non-constant density: existence, uniqueness and regularity
Authors: Antontsev S N , de Oliveira H B , Khompysh Kh
Published: May 2021

The classical Kelvin–Voigt equations for incompressible fluids with non-constant density are investigated in this work. To the associated initial-value problem endowed with zero Dirichlet conditions on the assumed Lipschitz-continuous boundary, we prove the existence of weak solutions: velocity and density. We also prove the existence of a unique pressure. These results are valid for d ∈ {2, 3, 4}. In particular, if d ∈ {2, 3}, the regularity of the velocity and density is improved so that their uniqueness can be shown. In particular, the dependence of the regularity of the solutions on the smoothness of the given data of the problem is established.
Hidden dynamics for piecewise smooth maps
Authors: Glendinning Paul , Jeffrey Mike R
Published: May 2021

We develop a hidden dynamics formulation of regularisation for piecewise smooth maps. This involves blowing up the discontinuity into an interval, but in contrast to piecewise smooth flows every preimage of the discontinuity needs to be blown up as well. This results in a construction similar to classic approaches to the Denjoy counterexample.
On a class of non-local phase-field models for tumor growth with possibly singular potentials, chemotaxis, and active transport
Authors: Scarpa Luca , Signori Andrea
Published: May 2021

This paper provides a unified mathematical analysis of a family of non-local diffuse interface models for tumor growth describing evolutions driven by long-range interactions. These integro-partial differential equations model cell-to-cell adhesion by a non-local term and may be seen as non-local variants of the corresponding local model proposed by Garcke et al (2016). The model in consideration couples a non-local Cahn–Hilliard equation for the tumor phase variable with a reaction–diffusion equation for the nutrient concentration, and takes into account also significant mechanisms such as chemotaxis and active transport. The system depends on two relaxation parameters: a viscosity coefficient and parabolic-regularization coefficient on the chemical potential. The first part of the paper is devoted to the analysis of the system with both regularizations. Here, a rich spectrum of results is presented. Weak well-posedness is first addressed, also including singular potentials. Then, under suitable conditions, existence of strong solutions enjoying the separation property is proved. This allows also to obtain a refined stability estimate with respect to the data, including both chemotaxis and active transport. The second part of the paper is devoted to the study of the asymptotic behavior of the system as the relaxation parameters vanish. The asymptotics are analyzed when the parameters approach zero both separately and jointly, and exact error estimates are obtained. As a by-product, well-posedness of the corresponding limit systems is established.
Linear instability criterion for the Korteweg–de Vries equation on metric star graphs
Authors: Angulo Pava Jaime , Cavalcante Márcio
Published: May 2021

The aim of this work is to establish a novel linear instability criterion for the Korteweg–de Vries (KdV) model on metric graphs. In the case of balanced graphs with a structure represented by a finite collection of semi-infinite edges and with boundary condition of δ-type interaction at the graph-vertex, we show that the continuous tail and bump profiles are linearly unstable. In this case, the use of the analytic perturbation theory of operators as well as the extension theory of symmetric operators is fundamental in our stability analysis. The arguments showed in this investigation have prospects in the study of the instability of stationary waves solutions for nonlinear evolution equations on metric graph.
The local universality of Muttalib–Borodin ensembles when the parameter θ is the reciprocal of an integer
Authors: Molag L D
Published: May 2021

The Muttalib–Borodin ensemble is a probability density function for n particles on the positive real axis that depends on a parameter θ and a weight w. We consider a varying exponential weight that depends on an external field V. In a recent article, the large n behavior of the associated correlation kernel at the hard edge was found for

θ
=

1
2

, where only few restrictions are imposed on V. In the current article we generalize the techniques and results of this article to obtain analogous results for

θ
=

1

r

, where r is a positive integer. The approach is to relate the ensemble to a type II multiple orthogonal polynomial ensemble with r weights, which can then be related to an (r + 1) × (r + 1) Riemann–Hilbert problem. The local parametrix around the origin is constructed using Meijer G-functions. We match the local parametrix around the origin with the global parametrix with a double matching, a technique that was recently introduced.
Effects of white noise on the violation of Bell-type inequalities based on probability theory
Authors: Dutta Arijit , Kim Jaewan , Lee Jinhyoung
Published: May 2021

We introduce two types of statistical quasi-separation between local observables to construct two-party Bell-type inequalities for an arbitrary dimensional systems and arbitrary number of measurement settings per site. Note that, the main difference between statistical quasi-separations and the usual statistical separations is that the former are not symmetric under exchange of the two local observables, whereas latter preserve the symmetry. We show that a variety of Bell inequalities can be derived by sequentially applying triangle inequalities which statistical quasi-separations satisfy. A sufficient condition is presented to show quantum violations of the Bell-type inequalities with infinitesimal values of critical visibility v
c.
Silicon-doped cylindrical arrays for ultra-broadband terahertz absorber with polarization independence
Authors: Fang Jimin , Wang Bo
Published: May 2021

A cylindrical silicon-doped terahertz absorber is proposed, which can have polarization-independent and ultra-broadband merits. The silicon-doped absorber consists of a double-layer cylindrical Si/SiO2 arrays, and its absorptivity can be more than 95% at 0.9–5.8 THz. The absorption of cylindrical absorber exceeds 90% at 0.9–5.8 THz within the incident angle of 0–52°. Besides, the energy distribution of the electromagnetic field is clearly shown by finite element method. Moreover, the absorber is analyzed by impedance matching theory, which can explain the phenomenon of high absorption efficiency. Compared with the reported reference planar absorber and reference broadband absorber, the cylindrical absorber has better absorption spectrum and relative bandwidth ratio. Therefore, the ultra-wideband terahertz absorber has great potential in the fields of biomedicine and thermal imaging.
Entropy generation and heat transfer analysis of alumina and carbon nanotubes based hybrid nanofluid inside a cavity
Authors: Sreedevi P , Reddy P Sudarsana
Published: May 2021

This article presents numerical investigation of heat transport, flow and entropy generation features of hybrid nanofluid, made up of Aluminum oxide, single – walled carbon nanotubes as nanoparticles and Ethylene glycol as base fluid, inside a square cavity. The resultant non-dimensional equations are numerically assessed by employing finite difference technique. The variations in the scatterings of isotherms, streamlines and entropy generation with diverse values of radiation parameter

(
0.01
≤
R
≤
0.1
)
,

volume fraction of parameter of alumina nanoparticle

(
0.01
≤
ϕ
2
≤
0.1
)

Prandtl number

(
5.2
≤
Pr
≤
8.2
)
,

Rayleigh number

(

10

4

≤

Ra

≤

10

5

)
,

volume fraction parameter of single—walled carbon nanotubes

(
0.01
≤
ϕ
1
≤
0.1
)

and magnetic parameter

0.1
≤
M
≤
0.7

have schemed through graphs. Rate of heat transfer augments from 8.2% to 17.6% in the case single—walled carbon nanotubes of volume fraction 0.05 are suspending into the base fluid, whereas, heat transfer rate rises from 8.2% to 12.4% in the case of alumina nanoparticles of volume fraction 0.05 are suspending into the base fluid.
Search for Lorentz Invariance Violation from stacked Gamma-Ray Burst spectral lag data
Authors: Agrawal Rajdeep , Singirikonda Haveesh , Desai Shantanu
Published: May 2021

A number of works have claimed detections of a turn-over in the spectral lag data for individual Gamma-Ray Bursts (GRBs), caused by an energy-dependent speed of light, which could be a possible manifestation of Lorentz invariance violation (LIV). Here, we stack the spectral lag data from a total of 37 GRBs (with a total of 91 measurements), to verify if the combined data is consistent with a unified model consisting of intrinsic astrophysical emission, along with another contribution due to LIV. We then carry out Bayesian model comparison to ascertain if this combined spectral lag data shows a preference for an energy-dependent speed of light, as compared to only an intrinsic astrophysical emission mechanism. We do not find a decisive evidence for such an energy-dependent speed of light for two different models of LIV. When we assume a constant intrinsic lag coupled with an unknown intrinsic scatter, we do not find any evidence for LIV. However, when we use GRB-dependent parameters to model the intrinsic emission, we get decisive evidence for LIV violation. We then carry out a search for LIV Standard Model Extension using this dataset as well as an independent search using a separate dataset consisting of rest-frame spectral lags. Finally, none of the models considered here with any of the aforementioned assumptions provide a good fit to the stacked spectral lag data, indicating that there is still missing Physics in the model for intrinsic spectral lags.
Analyzing the difference in image quality between different ghost imaging systems using a unified optical transfer function
Authors: Luo Bin , Bai Yanfeng , Fu Xiquan
Published: May 2021

The optical transfer function (OTF), which correspond to the frequency domain, is of fundamental importance in characterizing imaging ability in optical imaging systems. By using the Collins formula and the optical transfer matrix theory, a simple and unified analytical expression of OTF is presented in any ghost imaging (GI) system. By comparing the spectrum distribution of OTF between different GI systems, one can predict which imaging system can provide better imaging quality when the same imaging object is used. Theoretical and experimental results are also implemented to verify our results.
Extended phase diagram of La1–x
Ca
x
MnO3 by interfacial engineering*
Authors: Zhang Kexuan , Qu Lili , Jin Feng , Gao Guanyin , Hua Enda , Zhang Zixun , Wang Lingfei , Wu Wenbin
Published: May 2021

The interfacial enhanced ferromagnetism in maganite/ruthenate system is regarded as a promising path to broaden the potential of oxide-based electronic device applications. Here, we systematically studied the physical properties of La1−x
Ca
x
MnO3/SrRuO3 superlattices and compared them with the La1−x
Ca
x
MnO3 thin films and bulk compounds. The La1−x
Ca
x
MnO3/SrRuO3 superlattices exhibit significant enhancement of Curie temperature (T
C) beyond the corresponding thin films and bulks. Based on these results, we constructed an extended phase diagram of La1−x
Ca
x
MnO3 under interfacial engineering. We considered the interfacial charge transfer and structural proximity effects as the origin of the interface-induced high T
C. The structural characterizations revealed a pronounced increase of B–O–B bond angle, which could be the main driving force for the high T
C in the superlattices. Our work inspires a deeper understanding of the collective effects of interfacial charge transfer and structural proximity on the physical properties of oxide heterostructures.
Highly accurate theoretical study on spectroscopic properties of SH including spin–orbit coupling*
Authors: Zhao Shu-Tao , Liu Xin-Peng , Li Rui , Guo Hui-Jie , Yan Bing
Published: May 2021

The multi-reference configuration interaction method plus Davidson correction (MRCI+Q) are adopted to study the low-lying states of SH with consideration of scalar relativistic effect, core-valence (CV) electron correlation, and spin–orbit coupling (SOC) effect. The SOC effect on the low-lying states is considered by utilizing the full Breit–Pauli operator. The potential energy curves (PECs) of 10 Λ–S states and 18 Ω states are calculated. The dipole moments of 10 Λ–S states are calculated, and the variation along the internuclear distance is explained by the electronic configurations. With the help of calculated SO matrix elements, the possible predissociation channels of A2Σ+, c4Σ− and F2Σ− are discussed. The Franck–Condon factors of A2Σ+–X2Π, F2Σ−–X2Π and E2Σ+–X2Π transitions are determined, and the radiative lifetimes of A2Σ+ and F2Σ− states are evaluated, which are in good agreement with previous experimental results.
Magnetic phase diagram of single-layer CrBr3
*
Authors: Jiang Wei , Hou Yue-Fei , Li Shujing , Fu Zhen-Guo , Zhang Ping
Published: May 2021

We theoretically provide a magnetic phase diagram for the single-layer (SL) CrBr3, which could be effectively tuned by both strain engineering and charge doping in SL-CrBr3. Through systematical first-principles calculations and Heisenberg model Hamiltonian simulations, three different magnetic phases in SL-CrBr3, which are off-plane ferromagnetic, in-plane ferromagnetic and in-plane Néel-antiferromagnetic phases, are found in the strain and charge doping regimes we studied. Furthermore, our results show that higher order Heisenberg exchange parameters and anisotropy exchange parameters should be taken into account for accurately illustrating the magnetic phase transition in SL-CrBr3. As a result, we find from the SpinW simulation that the Curie temperature is about T
c = 38.4 K, which is well consistent with the experimental result 34 K [Nano Lett.
19 3138 (2019)]. The findings here may be confirmed in future experiments, and may be useful for the potential applications of SL-CrBr3 in spintronics field.
An artificial intelligence that increases simulated brain–computer interface performance
Authors: Olsen Sebastian , Zhang Jianwei , Liang Ken-Fu , Lam Michelle , Riaz Usama , Kao Jonathan C
Published: May 2021

Objective. Brain–computer interfaces (BCIs) translate neural activity into control signals for assistive devices in order to help people with motor disabilities communicate effectively. In this work, we introduce a new BCI architecture that improves control of a BCI computer cursor to type on a virtual keyboard. Approach. Our BCI architecture incorporates an external artificial intelligence (AI) that beneficially augments the movement trajectories of the BCI. This AI-BCI leverages past user actions, at both long (100 s of seconds ago) and short (100 s of milliseconds ago) timescales, to modify the BCI’s trajectories. Main results. We tested our AI-BCI in a closed-loop BCI simulator with nine human subjects performing a typing task. We demonstrate that our AI-BCI achieves: (1) categorically higher information communication rates, (2) quicker ballistic movements between targets, (3) improved precision control to ‘dial in’ on targets, and (4) more efficient movement trajectories. We further show that our AI-BCI increases performance across a wide control quality spectrum from poor to proficient control. Significance. This AI-BCI architecture, by increasing BCI performance across all key metrics evaluated, may increase the clinical viability of BCI systems.
Acoustic characteristics of aero internal combustion engines
Authors: Moshkov P A
Published: May 2021

This paper provides a brief overview of internal combustion engines’ noise generating mechanisms. Spectral, energy, and spatial characteristics of the sound field of internal combustion engines used in aviation as part of power plants of light aircraft and unmanned aerial vehicles are considered. The influence of load and flight conditions on the engine noise is considered. An example of the calculated noise estimation of a single-cylinder four-stroke engine is presented. The main methods of reducing internal combustion engine noise are formulated.
Using computer modelling when creating a heat exchanger for a complex cycle small-size gas turbine plant
Authors: Remchukov S S
Published: May 2021

Using the complex methodology of computer-aided design, calculation, and production, an experimental plate heat exchanger for a small-size gas turbine plant of complex cycle was created. Using a computer parametric 3D model of the base heat exchangers element (plate) allows for the design, calculation, optimization, and technological preparation of production automatically.. Experimental studies of the heat exchanger for the complex cycle small-size gas turbine plant created according to the proposed methodology confirm its reliability and accuracy.
Estimation of cooling flow rate for conceptual design stage of a gas turbine engine
Authors: Filinov E P , Kuz’michev V S , Tkachenko Yu A , Ostapyuk Ya A , Omar H H , Krupenich I N
Published: May 2021

Development of a gas turbine engine starts with optimization of the working process parameters. Turbine inlet temperature is among the most influential parameters that largely determine performance of an engine. As typical turbine inlet temperatures substantially exceed the point where metal turbine blades maintain reasonable thermal strength, proper modeling of the turbine cooling system becomes crucial for optimization of the engine’s parameters. Currently available numerical models are based on empirical data and thus must be updated regularly. This paper reviews the published information on turbine cooling requirements, and provides an approximation curve that generalizes data on all types of blade/vane cooling and is suitable for computer-based optimization.
A study on the geometric characteristic influence on the liquid fuel flow in a three-way pressure-swirl atomizer
Authors: Gurakov N I M , Morales Hernandez , Zubrilin I A , Bolychev S A , Didenko A A , Matveev S G
Published: May 2021

An important factor that affects the characteristics of combustion processes in the combustion chambers of aircraft engines is the fuel atomization. Semi-empirical methods are usually used to determine the characteristics of liquid fuel atomization by pressure-swirl atomizers. The input data for semi-empirical methods are the geometric parameters of the atomizer, as well as the spray cone angle and the nozzle discharge characteristic. These parameters can be obtained experimentally, which requires the availability of appropriate apparatus and a sample of a pressure-swirl atomizer, which is associated with significant material costs. An alternative way to determine these characteristics is to use numerical methods for modelling two-phase flows. Therefore, it is convenient to use a combination of empirical and numerical methods (hybrid method) to determine the spray parameters of a pressure-swirl atomizer. In this paper, we studied the effect of geometric and operating parameters on spray characteristics using the hybrid method, which includes the volume of fluid (VOF) numerical method and the semi-empirical equation. The calculation results are compared with empirical generalizations and experimental data of such parameters as the discharge coefficient, the air core ratio and the spray cone angle. The results of this work were compared with the values of such parameters as the air core ratio and the spray cone angle obtained using the proposed method and analytical techniques.
Abnormal separated flow intensification and heat transfer enhancement in single-row inclined oval-trench dimples on the narrow channel wall
Authors: Isaev S A , Leontiev A I , Nikushchenko D V , Son E E
Published: May 2021

Intensification of turbulent separated air flow and heat transfer enhancement at the hydrodynamic stabilization length on the periodic section of the narrow channel with inclined one-row oval-trench dimples (OTDs) is analyzed. The periodic section of the channel of height equal to 1, length – 8, and width – 9 is considered at Re=104. The inclined OTD 0.5 in width, 7.05 in length, and 0.25 in depth is located in the center of the heated isothermal wall. The rounding radius of the dimple edge is 0.21. The OTD inclination angle varies from 0° to 52.5°. It is found that the optimal inclination angles in terms of thermal and hydraulic performance (THP) are equal to 45° and 30°. It is observed that at large inclination angles the minimum value of relative friction decreases many times (up to-3.5).
Development of a method for manufacturing ceramic tooling for precision casting of blades made of heat-resistant alloys using additive technologies
Authors: Magerramova L A , Kozlov B G , Protasov V E
Published: May 2021

The technology traditionally used to produce castings of gas turbine engine (GTE) blades involves a large number of alterations, high labor costs due to the large amount of manual labor required, and complex and expensive equipment and tooling. This technology is only suited for large-scale production due to its use of expensive reusable metal molds.

The ceramic shell mold for turbine cooled and uncooled blades can be manufactured more quickly and cheaply. This is especially important for fast hardware redesign and reconfiguration.

This proposal describes an approach for producing a shell mold including with an internal rod using three-dimensional (3D) printing with refractory ceramic pastes that does not involve a lengthy and time-consuming process of designing and manufacturing forming equipment for the production of castings based on smelted models.
Spectral pyrometry of surface and flame
Authors: Mosharov V E , Radchenko V N , Senyuev I V
Published: May 2021

The development of high-speed aircraft requires the study of high-temperature materials and of combustion processes in engine combustion chambers. One of the main parameters in these studies is the temperature, which must be measured up to 3000K. Such high temperatures can be measured only by non-contact methods. One of these methods is spectral pyrometry, which is based on temperature measurement from the energy distribution in thermal radiation spectrum of investigated object. This paper presents the results of spectral pyrometry application to measure the surface temperatures and hydrocarbon flame temperatures.
Modelling the optical part of a tomographic system for measuring the gas flow local temperatures
Authors: Pechinskaya O V , Macuk A S , Yu Poroykov A , Lapitskiy K M
Published: May 2021

This paper describes a technique for modelling the optical part of a tomographic system for measuring local temperatures of a gas flow. The system is based on the use of a spectral ratio pyrometer. The parameters of the optical part of the tomographic system with a lens part of two configurations are modeled: a single lens and a single lens paired with a microscope objective lens. Diagrams of scattering spots, illumination distributions in the cross section of the beam, and average values of the total radiation power in the focal plane of the optical system are obtained. Recommendations are given for the elimination of parasitic illumination in a pyrometer, as well as for further improvement of the tomographic system lens.
Studying the dependence of model combustion chamber integral characteristics on the flow duct geometrical parameters during two-component mixture burning
Authors: Guskov O V , Zakharov V S , Minko A V
Published: May 2021

This paper presents numerical simulation results of hydrogen combustion in variable flow ducts. The study was carried out in three-dimensional formulation using the chemical kinetic mechanism. Several configurations of the flow paths were examined. Relative thrust and combustion efficiency were selected as criteria for comparing the flow ducts. The results of the numerical simulation were compared with the results obtained within the framework of a one-dimensional calculation. The presented results can be used at the calculating stage of the operational process in the advanced power units.
Surrogate modeling of the CLIC final-focus system using artificial neural networks
Authors: Ögren J. , Gohil C. , Schulte D.
Published: May 2021

Artificial neural networks can be used for creating surrogate models that can replace computationally expensive simulations. In this paper, a surrogate model was created for a subset of the Compact Linear Collider (CLIC) final-focus system. By training on simulation data, we created a model that maps sextupole offsets to luminosity and beam sizes, thus replacing computationally intensive tracking and beam-beam simulations. This model was then used for optimizing the parameters of a random walk procedure for sextupole alignment.
Multiple constraints on urban bird communication: both abiotic and biotic noise shape songs in cities
Authors: To Ann W Y , Dingle Caroline , Collins Sarah A
Published: May 2021

Ambient noise can cause birds to adjust their songs to avoid masking. Most studies investigate responses to a single noise source (e.g., low-frequency traffic noise, or high-frequency insect noise). Here, we investigated the effects of both anthropogenic and insect noise on vocalizations of four common bird species in Hong Kong. Common Tailorbirds (Orthotomus sutorius) and Eurasian Tree Sparrows (Passer montanus) both sang at a higher frequency in urban areas compared to peri-urban areas. Red-whiskered Bulbuls (Pycnonotus jocosus) in urban areas shifted the only first note of their song upwards. Swinhoe’s White-eye (Zosterops simplex) vocalization changes were correlated with noise level, but did not differ between the peri-urban and urban populations. Insect noise caused the Eurasian Tree Sparrow to reduce both maximum, peak frequency, and overall bandwidth of vocalizations. Insect noise also led to a reduction in maximum frequency in Red-whiskered bulbuls. The presence of both urban noise and insect noise affected the sound of the Common Tailorbirds and Eurasian Tree Sparrows; in urban areas, they no longer increased their minimum song frequency when insect sounds were also present. These results highlight the complexity of the soundscape in urban areas. The presence of both high- and low-frequency ambient noise may make it difficult for urban birds to avoid signal masking while still maintaining their fitness in noisy cities.
Study of luminescent coupling effect in modeling a concentrator photovoltaic system with III-V triple junction solar cell
Authors: Liu Zhezhi , Lv Hui , Hu Yue , Liao Jun , Zhou Hang , Su Yuehong
Published: May 2021

A theoretical model is proposed for a concentrator photovoltaic (CPV) system. This model is based on the two-diode equation and considers the luminescent coupling (LC) effect in III-V triple junction solar cell. By using the model, the ‘I-V’ curve of the system is fitted. The fitting result is in good agreement with the experimental data. The system’s open circuit voltage is also predicted in a certain temperature range. Based on the analysis of the simulation results and the two-diode equation, it is concluded that the LC effect should be a non-negligible mechanism for analyzing the operation performance of CPV system.
Japonica Array NEO with increased genome-wide coverage and abundant disease risk SNPs
Authors: Sakurai-Yageta Mika , Kumada Kazuki , Gocho Chinatsu , Makino Satoshi , Uruno Akira , Tadaka Shu , Motoike Ikuko N , Kimura Masae , Ito Shin , Otsuki Akihito , Narita Akira , Kudo Hisaaki , Aoki Yuichi , Danjoh Inaho , Yasuda Jun , Kawame Hiroshi , Minegishi Naoko , Koshiba Seizo , Fuse Nobuo , Tamiya Gen , Yamamoto Masayuki , Kinoshita Kengo
Published: May 2021

Ethnic-specific SNP arrays are becoming more important to increase the power of genome-wide association studies in diverse population. In the Tohoku Medical Megabank Project, we have been developing a series of Japonica Arrays (JPA) for genotyping participants based on reference panels constructed from whole-genome sequence data of the Japanese population. Here, we designed a novel version of the SNP array for the Japanese population, called Japonica Array NEO (JPA NEO), comprising a total of 666,883 markers. Among them, 654,246 tag SNPs of autosomes and X chromosome were selected from an expanded reference panel of 3,552 Japanese, 3.5KJPNv2, using pairwise r2 of linkage disequilibrium measures. Additionally, 28,298 markers were included for the evaluation of previously identified disease risk markers from the literature and databases, and those present in the Japanese population were extracted using the reference panel. Through genotyping 286 Japanese samples, we found that the imputation quality r2 and INFO score in the minor allele frequency bin >2.5–5% were >0.9 and >0.8, respectively, and >12 million markers were imputed with an INFO score >0.8. From these results, JPA NEO is a promising tool for genotyping the Japanese population with genome-wide coverage, contributing to the development of genetic risk scores.
Plasticity in Oviposition Site Selection Behavior in Drosophila suzukii (Diptera: Drosophilidae) in Relation to Adult Density and Host Distribution and Quality
Authors: Elsensohn Johanna E , Schal Coby , Burrack Hannah J
Published: May 2021

Flexibility in oviposition site selection under temporally shifting environmental conditions is an important trait that allows many polyphagous insects to flourish. Population density has been shown to affect egg-laying and offspring fitness throughout the animal kingdom. The effects of population density in insects have been suggested to be mutualistic at low densities, whereas intraspecific competition is exhibited at high densities. Here, we explore the effects of adult crowding and spatial resource variation on oviposition rate in the invasive pest Drosophila suzukii (Matsumura). In a series of laboratory experiments, we varied the density of adult males and females while holding oviposition substrate availability constant and measured per female oviposition rate using high and low-quality substrates. We found that oviposition behavior was affected more by substrate than adult density, though both variables had significant effects. When we varied the spatial arrangement of whole raspberries, we observed differences in oviposition rate and egg distribution between the grouped and solitary female treatments. Our results suggest that social interactions encourage oviposition, especially when exposed to unfamiliar or unnatural substrates. These results highlight the compensating effect of increased oviposition rate per female as adult populations decline. They will help researchers and crop managers better understand in-field population dynamics throughout the season as population densities change.
Gluten-free diet can ameliorate the symptoms of non-celiac autoimmune diseases
Authors: Lerner Aaron , Freire de Carvalho Jozélio , Kotrova Anna , Shoenfeld Yehuda
Published: May 2021

Context

A gluten-free diet (GFD) is the recommended treatment for gluten-dependent disease. In addition, gluten withdrawal is popular and occasionally is suggested as a treatment for other autoimmune diseases (ADs).

Objective

The current systematic review summarizes those entities and discusses the logic behind using a GFD in classical non–gluten-dependentADs.

Data Sources

A search for medical articles in PubMed/MEDLINE, Web of Sciences, LILACS, and Scielo published between 1960 and 2020 was conducted, using the key words for various ADs and GFDs.

Data Exxtraction

Eight-three articles were included in the systematic review (using PRISMA guidelines).

Data Analysis

Reduction in symptoms of ADs after observance of a GFD was observed in 911 out of 1408 patients (64.7%) and in 66 out of the 83 selected studies (79.5%). The age of the patients ranged from 9 months to 69 years. The duration of the GFD varied from 1 month to 9 years. A GFD can suppress several harmful intraluminal intestinal events. Potential mechanisms and pathways for the action of GFD in the gut – remote organs’ axis have been suggested.

Conclusion

A GFD might represent a novel nutritional therapeutic strategy for classical non–gluten-dependent autoimmune conditions.
Quantifying multipliers in Italy: does fiscal policy composition matter?
Authors: Deleidi Matteo
Published: May 2021

This article aims to estimate fiscal multipliers in Italy by assessing the effect of an increase in government expenditure and taxes on the Gross Domestic Product (GDP). By applying structural vector autoregressive modelling to Italian quarterly data for the 1995–2019 period, I show that expansionary fiscal policies produce positive effects on the GDP level. Estimated spending multipliers are higher than 1, and when government investment and consumption are compared, findings show that government investment has a larger effect on GDP than government consumption. Estimated tax multipliers are lower than 1, and tax-based policies are less effective in stimulating GDP than expenditure-based fiscal plans. My findings strongly support the Keynesian perspective and indicate that Italy should increase public investments considerably in order to foster economic growth.