bluuebunny/crossref_metadata_2025_split huggingface dataset:
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

Abstract
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

Abstract
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

Abstract
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

Abstract
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

Abstract
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

Abstract
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

Abstract
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

Abstract
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

Abstract
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

Abstract
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

Abstract
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.
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

Abstract

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

Abstract
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

Abstract
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

Abstract
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

Abstract

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

Abstract
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

Abstract
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

Abstract
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

Abstract
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

Abstract
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

Abstract
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.