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Second-Order Invariant Domain Preserving ALE Approximation of Euler Equations

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Communications on Applied mathematics and Computation 2023年第2期5卷 923-945页

作者： Jean-Luc Guermond Bojan popov Laura Saavedra Department of mathematics Texas A&M UniversityCollege StationUSA Departamento de matemática Aplicada a la Ingeniería Aeroespacial Universidad Politécnica de MadridMadridSpain

An invariant domain preserving arbitrary Lagrangian-Eulerian method for solving non-linear hyperbolic systems is *** numerical scheme is explicit in time and the approximation in space is done with continuous finite *** method is made invar-iant domain preserving for the Euler equations using convex limiting and is tested on vari-ous benchmarks.

关键词： Conservation equations Hyperbolic systems Arbitrary Lagrangian-Eulerian moving meshes Invariant domains High-order method Convex limiting Finite element method

New observations and transit solutions of the inflated exoplanets HAT-P-40b and HAT-P-51b

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Research in Astronomy and Astrophysics 2021年第2期21卷 157-160页

作者： Diana P.Kjurkchieva Nikola I.Petrov Velimir A.popov Department of Physics and Astronomy Shumen University115 Universitetska str.9700 ShumenBulgaria Institute of Astronomy and NAO Bulgarian Academy of SciencesTsarigradsko shossee 721784 SofiaBulgaria

We present high-precision photometric observations of the transiting exoplanets HAT-P-40 b and HAT-P-51 b by the Rozhen 2-m *** newly-observed transit of HAT-P-40 b is the first one with a complete *** orbital periods of the two targets were *** modeled the observed transits and found bigger stellar radii than those derived from the stellar *** planet radii of HATP-40 b and HAT-P-51 b obtained from our transit solutions are bigger than the values calculated by the empirical relations for Jupiter-mass and Saturn-mass planets *** values reveal the highlyinflated nature of the two targets,especially that of HAT-P-51 *** established that the best transit solutions correspond to a quadratic limb-darkening *** fitted limb-darkening coefficients of HAT-P-40 are close to the theoretical ones while those of HAT-P-51 are a little *** precise astrometric Gaia distances of the two targets are smaller by 6%–7%than the calculated values from the stellar *** propose the Gaia distances to be used for improvement of the stellar models as well as for more reliable calculation of the parameters of the known exoplanets.

关键词： (Stars )planetary systems-techniques photometric-Stars individual(HAT-P-40 and HAT-P-51)

NSVS 2569022:a peculiar binary among W Uma stars with extremely small mass ratios

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Research in Astronomy and Astrophysics 2018年第10期18卷 123-130页

作者： Diana P.Kjurkchieva Velimir A.popov Nikola I.Petrov Department of Physics and Astronomy Shumen University Institute of Astronomy and NAO Bulgarian Academy of Sciences

Photometric observations of the W Uma binary NSVS 2569022 are presented. The light curve solution reveals that both components are of F spectral type （temperatures T1 = T2 = 6100 K）. NSVS 2569022 undergoes a total eclipse of W subtype and the mass ratio is well-determined. Its extremely small value of only 0.077 implies that the target will probably experience instability and a possible merger. This value ranks NSVS 2569022 in sixth place among binaries with the smallest mass ratio. Based on an empirical relation of ＂period - total mass＂ for low mass-ratio binaries, we estimate the global parameters of NSVS 2569022： masses m1 = 1.17 m⊙ and m2 = 0.09 m⊙; radii R1 = 1.19 R⊙ and R2 = 0.38 R⊙; luminosities L1 = 1.73 L⊙ and L2 = 0.17L⊙. An analysis of the characteristics of binaries with extremely low-mass ratios is made. NSVS 2569022 turns out to be a peculiar binary among W Uma stars with extremely small mass ratios due to its unexpectedly small fill-out factor of only 0.014 （slightly overcontact configuration）.

关键词： binaries eclipsing - binaries close - stars fundamental parameters - stars individual(NSVS 2569022)

Correlation of microstructure and magnetic properties in Sm(Co_(bal)Fe_(0.1)Cu_(0.1)Zr_(0.033))_(6.93) magnets solution-treated at different temperatures

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Rare metals 2019年第1期38卷 20-28页

作者： Cheng Xu Hui Wang Tian-Li Zhang Alexander popov Raghavan Gopalan Cheng-Bao Jiang School of materials Science and Engineering Beihang University m.N. miheev Institute of metal Physics Ural Branch of Russian Academy of Sciences International Advanced Research Centre for Powder metallurgy and New materials(ARCI) IITM Research Park

The correlation of microstructure and magnetic properties in Sm(Co_(bal)Fe_(0.1)Cu_(0.1)Zr_(0.033))_(6.93) magnets solution-treated at different temperatures was systematically investigated. It is found that the magnets solution-treated at 1219℃ possess a single 1:7 H phase, exhibiting the homogeneous cellular structure during further aging treatment, leading to the optimum magnetic properties. However, for the magnets solution-treated at 1211 and 1223℃,2:17 H or 1:5 H secondary phase will also form besides 1:7 H main phase, which cannot transform into cellular structure,thus deteriorating the magnetic properties greatly. The irreversible magnetization investigations with recoil loops also propose a non-uniform pinning in the magnets induced by the secondary precipitates. At proper solution temperature, Zr is supposed to occupy the Fe-Fe dumbbell sites in the form of Zr-vacancy pairs, leading to the minimum c/a ratio and thus stabilizing the 1:7 H phase. Finally,Sm(Co_(bal)Fe_(0.1)Cu_(0.1)Zr_(0.033))_(6.93) magnets with the maximum energy product and intrinsic coercivity at 550℃ up to 60.73 kJ·m^(-3) and 553.88 kA·m^(-1) were prepared by powder metallurgy method.

关键词： Sm2Co17 Solution treatment Phase constitution Demagnetization curve squareness

Dimethylammonium iodide stabilized bismuth halide perovskite photocatalyst for hydrogen evolution

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Nano Research 2021年第4期14卷 1116-1125页

作者： He Zhao Kalyani Chordiya Petri Leukkunen Alexey popov mousumi Upadhyay Kahaly Krisztian Kordas Satu Ojala Environmental and Chemical Engineering Research Unit University of OuluP.O.Box 4300FI-90014 OuluFinland ELI-ALPS ELI-HU Non-Profit Ltd.Dugonicster 136720 SzegedHungary Institute of Physics University of Szegedf D6m ter 9H-6720 Szeged Hungary Nano and molecular Systems Research Unit University of OuluP.O.Box 3000FI-90014 OuluFinland Optoelectronics and measurement Techniques Unit University of OuluFI-90570 OuluFinland microelectronics Research Unit University of OuluP.O.Box 4500FI-90014 OuluFinland VTT Technical Research Centre of Finland FI-90590 OuluFinland

metal halide perovskites have emerged as novel and promising photocatalysts for hydrogen ***,their stability in water is a vital and urgent research *** this paper a novel approach to stabilize a bismuth halide perovskite[(CH_(3))_(2)NH_(2)]_(3)[Bil_(6)](DA_(3)Bil_(6))in water using dimethylammonium iodide(DAI)without the assistance of acids or coatings is *** DA3Bil6 powder exhibits good stability in DAI solutions for at least two *** concentration of DAI is found as a critical parameter,where the I^(-)ions play the key role in the *** stability of DA3Bil6 in water is realized via a surface dissolution-recrystallization *** DA3Bil6 demonstrates constant photocatalytic properties for visible light-induced photo-oxidation of I^(-)ions and with PtCI4 as a co-catalyst(Pt-DA_(3)Bil_(6)),photocatalytic H2 evolution with a rate of 5.7μmol·h^(-1)from HI in DAI solution,obtaining an apparent quantum efficiency of 0.83%at 535 *** study provides new insights on the stabilization of metal halide perovskites for photocatalysis in aqueous solution.

关键词： bismuth halide perovskite dimethylammonium iodide photocatalysis hydrogen evolution

multi-layered tissue head phantoms for noninvasive optical diagnostics

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Journal of Innovative Optical Health Sciences 2015年第3期8卷 36-45页

作者： m.S.Wróbel A.P.popov A.V.Bykov m.Kinnunen m.Jędrzejewska-Szczerska V.V.Tuchin Department of metrology and Optoelectronics Gdansk University of Technology Gabriela Narutowicza Street 11/1280-233 Gdansk Poland Optoelectronics and measurement Techniques Laboratory Faculty of Information Technology and Electrical Engineering University of Oulu P.O.Box 4500 FI-90014 OuluFinland Research-Educational Institute of Optics and Biophotonics Saratov State University Saratov 410012Russia Institute of Precise mechanics and Control Russian Academy of Sciences Saratov 410028Russia

Extensive research in the area of optical sensing for medical diagnostics requires development of tissue phantoms with opt ical properties similar to those of living human *** and improvement of in vivo optical measurement systems requires the 1use of stable tissue phantoms with known characteristics,which are mainly used for calibration of such systems and testing their performance over *** and mechanical properties of phantoms depend on their ***,they must accurately simulate specific tssues they are supposed to *** tsues and organs including head possess a multi-layered structure,with specifie optical properties of each ***,such a structure is not always addressed in the present-day *** this paper,we focus on the development of a plain-parallel multi-layered phantom with optical properties(reduced scattering oofficientμ'and absorption cofficientμa)corresponding to the human head layers,such as skin,skul,and gray and white matter of the brain *** phantom is intended for use in noninvasive diffuse near-infrared spectroscopy(NIRS)of humnan *** parameters of the fabricated phantoms are reconstructed using spectrophotometry and inverse adding-doubling calculation *** results show that polyinyl chloride plastisol(PVCP)and zinc oxide(ZnO)nanoparticles are suitable materials for fabrication of tissue mimicking phantoms with controlled scattering *** matching was found between optical properties of phantoms and the corresponding values found in the literature.

关键词： Tissue-mimicking phantoms optical properties near-infrared spectroscopy head model

The W Uma binaries USNO-A2.0 1350-17365531,V471 Cas,V479 Lac and V560 Lac:light curve solutions and global parameters based on Gaia distances

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Research in Astronomy and Astrophysics 2019年第1期19卷 141-148页

作者： Diana P.Kjurkchieva Velimir A.popov Yordanka Eneva Nikola I.Petrov Department of Physics and Astronomy Shumen University medical University Institute of Astronomy and NAO Bulgarian Academy of Sciences

We present photometric observations in Sloan filters g′, i′of the eclipsing W Uma stars USNOA2.0 1350-17365531, V471 Cas, V479 Lac and V560 Lac. The sinusoidal-like O-C diagram of V471 Cas indicates the presence of a third body with mass 0.12 m_⊙(a red dwarf) at distance 897 R_⊙. The O-C diagram of V479 Lac reveals a period decrease of d P/dt =-1.69 × 10-6d yr-1. The results of the light curve solutions are:(i) the targets are overcontact binaries with small fill-out factors;(ii) their components are F–K stars, comparable in size, whose temperature differences are below 80 K;(iii) all targets undergo partial eclipses and to limit the possible mass ratios we carried out two-step q-search analysis. The target global parameters(luminosities, radii, masses) were obtained on the basis of their Gaia distances and the results of our light curve solutions. The obtained total mass of V560 Lac turns out to be smaller than the lower mass limit for presently known W Uma binaries of 1.0-1.2 m_⊙, i.e. this target is a peculiar overcontact system.

关键词： binaries:close binaries:eclipsing methods:data analysis stars:fundamental parameters stars:individual(USNO-A2.0 1350-17365531,V471 Cas,V479 Lac,V560 Lac)

Aryl Hydrocarbon Receptor is Involved in the Proinflammatory Cytokine Response to Cadmium

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Biomedical and Environmental Sciences 2021年第3期34卷 192-202页

作者： KULAS Jelena TUCOVIC Dina ZELJKOVIC milica popovIC Dusanka popov ALEKSANDROV Aleksandra KATARANOVSKI milena mIRKOV Ivana Immunotoxicology Group Department of EcologyInstitute for Biological Research‘Sinisa Stankovic'-National Institute of Republic of SerbiaUniversity of Belgrade142 Bulevar despota StefanaBelgrade 11000Serbia

Objective To investigate involvement of the aryl hydrocarbon receptor(Ah R)in the immunomodulatory effects of cadmium(Cd).methods The effect of Cd on Ah R activation(CYP1 A1 and CYP1 B1 m RNA expression)was examined in lung leukocytes of Cd-exposed rats(5 and 50 mg/L,30 d orally)and by in vitro leukocyte *** involvement of Ah R signaling in the effects of Cd on the interleukin(IL)-1β,IL-6,and tumor necrosis factor(TNF)lung leukocyte response was investigated in vitro using the receptor antagonist *** Cd increased CYP1 B1(in vivo and in vitro)and CYP1 A1(in vitro)m RNA,indicating Ah R involvement in the action of *** response to Cd,lung leukocytes increased IL-6 and decreased TNF at the gene expression and protein levels,but decreased IL-1βproduction due to reduced *** Ah R antagonist CH-223191 abrogated the observed effects of Cd on the cytokine *** absence of Ah R reactivity and cytokine response to Cd of leukocytes from the lungs of a rat strain that is less sensitive to Cd toxicity coincided with a high Ah R repressor m RNA *** Ah R signaling is involved in the lung leukocyte proinflammatory cytokine response to *** relevance of the Ah R to the cytokine response to Cd provides new insight into the mechanisms of Cd immunotoxicity.

关键词： Cadmium Lung leukocytes Aryl hydrocarbon receptor Cytokine(IL-6,TNF,IL-1β)response

Security and Privacy Challenges in SDN-Enabled IoT Systems: Causes, Proposed Solutions,and Future Directions

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Computers, materials & Continua 2024年第8期80卷 2511-2533页

作者： Ahmad Rahdari Ahmad Jalili mehdi Esnaashari mehdi Gheisari Alisa A.Vorobeva Zhaoxi Fang Panjun Sun Viktoriia m.Korzhuk Ilya popov Zongda Wu Hamid Tahaei Institute of Artificial Intelligence Shaoxing UniversityShaoxing312000China Department of Computer Engineering Gonbad Kavous UniversityGonbad-e Kavus49717-99151Iran Faculty of Computer Engineering K.N.Toosi University of TechnologyTehran196976-4499Iran Department of Computer Science and Engineering Saveetha School of EngineeringSaveetha Institute of Medical and Technical SciencesChennai602105India Secure Information Technologies Department National Research University ITMOSt.Petersburg197101Russia School of Electrical and Computer Engineering Shiraz UniversityShiraz71946–84334Iran Department of Computer Science and Engineering Islamic Azad UniversityDamavand***Iran Department of R&D Shenzhen BKD Co.Ltd.Shenzhen518000China

Software-Defined Networking(SDN)represents a significant paradigm shift in network architecture,separating network logic from the underlying forwarding devices to enhance flexibility and centralize ***-rently,the Internet of Things(IoT)connects numerous devices to the Internet,enabling autonomous interactions with minimal human ***,implementing and managing an SDN-IoT system is inherently complex,particularly for those with limited resources,as the dynamic and distributed nature of IoT infrastructures creates security and privacy challenges during SDN *** findings of this study underscore the primary security and privacy challenges across application,control,and data planes.A comprehensive review evaluates the root causes of these challenges and the defense techniques employed in prior works to establish sufficient secrecy and privacy *** investigations have explored cutting-edge methods,such as leveraging blockchain for transaction recording to enhance security and privacy,along with applying machine learning and deep learning approaches to identify and mitigate the impacts of Denial of Service(DoS)and Distributed DoS(DDoS)***,the analysis indicates that encryption and hashing techniques are prevalent in the data plane,whereas access control and certificate authorization are prominently considered in the control plane,and authentication is commonly employed within the application ***,this paper outlines future directions,offering insights into potential strategies and technological advancements aimed at fostering a more secure and privacy-conscious SDN-based IoT ecosystem.

关键词： Security privacy-preserving software-defined network internet of things