检索结果-南通市图书馆

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

在线全文

学校读者我要写书评

暂无评论

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 telescope.The newly-observed transit of HAT-P-40 b is the first one with a complete curve.The orbital periods of the two targets were improved.We modeled the observed transits and found bigger stellar radii than those derived from the stellar models.The 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 respectively.Their values reveal the highlyinflated nature of the two targets,especially that of HAT-P-51 b.We established that the best transit solutions correspond to a quadratic limb-darkening law.The fitted limb-darkening coefficients of HAT-P-40 are close to the theoretical ones while those of HAT-P-51 are a little different.The precise astrometric Gaia distances of the two targets are smaller by 6%–7%than the calculated values from the stellar models.We 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)

V2551 Cyg:a pulsating star with enigmatic peculiarities

在线全文

学校读者我要写书评

暂无评论

Research in Astronomy and Astrophysics 2017年第7期17卷 57-66页

作者： Diana P.Kjurkchieva Velimir a.popov Dragomir V.Marchev Kenneth T.Menzies Nikola I.Petrov Department of Physics Shumen University IRIDA Observatory Rozhen NAO Tigh Speuran Observatory Institute of Astronomy and NAO Bulgarian Academy of Sciences

Intensive photometric and spectral observations of the variable star V2551 Cyg are presented.The light curve shape reveals that the target is a pulsating star, contrary to its previous classification as an eclipsing binary. The period and amplitude of the light curve, the amplitudes of color changes and the radial velocity curve of V2551 Cyg are similar to those of a high-amplitude δ Scuti variable. The target seems to pulsate with the fundamental mode. However, V2551 Cyg exhibits several important peculiarities：（i） the decreasing branch of its light curve is steeper than the increasing one;（ii） the radial velocity curve has a flat section in the phase range 0.7-1.2 and short increase of the negative radial velocity at phase 0.7;（iii） the rotational velocity is quite big for a HADS star;（iv） the Fourier coefficients of V2551 Cyg are quite different from those of HADS stars. The target classification is difficult due to these peculiarities.

关键词： stars variables delta Scuti - stars variables RR Lyrae - stars individual （V2551 Cyg）

Symmetry Reduction upon Size Mismatch:The Non-lcosahedral Intermetalloid Cluster [Co@Ge12]^3-

在线全文

学校读者我要写书评

暂无评论

Chinese Journal of Chemistry 2018年第12期36卷 1165-1168页

作者： Chao Liu Lei-Jiao Li Ivan a.popov Robert J.Wilson Cong-qiao Xu Jun Li Alexander I.Boldyrev Zhong-Ming Sun State Key Laboratory of Rare Earth Resource Utilization Changchun Institute of Applied ChemistryChinese Academy of Sciences5625 Renmin StreetChangchunJilin 130022China University of Chinese Academy of Sciences Beijing 100049China School of Materials Science and Engineering Research Center of Rare Earth and Inorganic Functional MaterialsNankai UniversityTianjin 300350China School of Chemistry & Environmental Engineering Chang chun University of Science & TechnologyChangchunJilin 130022China Department of Chemistry and Biochemistry Utah State University0300 Old Main HillLosanUtah84322-0300USA Fachbereich Chemie und Wissenschaftliches Zentrum fur Materialwissenschaften (WZMW) Philipps-Universtat MarburgHans-Meerwein-Straβe35043 MarburgGermany Department of Chemistry and Key Laboratory of Organic Optoelectronics & Molecular Engineering of Ministry of Education Tsinghua UniversityBeijing 200084China

A new complex comprising [Co@Ge 12 ] 3– cluster core was synthesized through the reaction of CoMe(PMe 3 ) 4 and K 4 Ge 9 in ethylenediamine solution. The pseudo‐ D 5d geometry of this cluster can be viewed as structurally derived from an icosahedral cage via Jahn‐Teller effect, leading to notable bonding differences from I h ‐[M@E 12 ] q − clusters (E = Sn, Pb with q = 2, 3). The [Co@Ge 12 ] 3– cluster represents a structural conundrum. On the basis of the geometric considerations it could be viewed as a sandwich complex. However, chemical bonding analysis revealed that there is a direct covalent multicenter bonding between the two pentagons, thus indicating that the structure should be viewed as an elongated icosahedron. Further theoretical calculations on [M@Ge 12 ] 3− (M = Rh, Ir, Mt) indicate that similar compounds of larger‐size metal atoms can drive the complete transformation of [M@Ge 12 ] 3− clusters from icosahedron structure to a sandwich one.

关键词： Zintl ions intermetalloid cluster icosahedron Sandwich complex

Approximate contact solutions for non-axisymmetric homogeneous and power-law graded elastic bodies:A practical tool for design engineers and tribologists

在线全文

维普期刊数据库

学校读者我要写书评

暂无评论

Friction 2024年第2期12卷 340-355页

作者： Valentin L.popov Qiang LI Emanuel WILLERT Institute of Mechanics Technische Universität BerlinBerlin 10623Germany

In two recent papers,approximate solutions for compact non-axisymmetric contact problems of homogeneous and power-law graded elastic bodies have been suggested,which provide explicit analytical relations for the force–approach relation,the size and the shape of the contact area,as well as for the pressure distribution therein.These solutions were derived for profiles,which only slightly deviate from the axisymmetric shape.In the present paper,they undergo an extensive testing and validation by comparison of solutions with a great variety of profile shapes with numerical solutions obtained by the fast Fourier transform(FFT)-assisted boundary element method(BEM).Examples are given with quite significant deviations from axial symmetry and show surprisingly good agreement with numerical solutions.

关键词： normal contact non-axisymmetric indenter extremal principle generalized method of dimensionality reduction(MDR) functional elastic grading

Web service for biodiversity estimation using remote sensing data

在线全文

维普期刊数据库

学校读者我要写书评

暂无评论

International Journal of Digital Earth 2008年第4期1卷 367-376页

作者： Mikhail a.popov Nataliia N.Kussul Sergey A.Stankevich Anna A.Kozlova Andrii Yu.Shelestov Oleksii M.Kravchenko Mykhailo B.Korbakov Serhiy V.Skakun Scientific Centre for Aerospace Research of the Earth KievUkraine Department of Space Information Technologies and Systems Space Research Institute NASU-NSAUKievUkraine

This paper presents a technique for the assessment and mapping of land biodiversity by using remote sensing data.The proposed approach uses a fuzzy model that encapsulates different ecological factors influencing biod... 详细信息

关键词： potential biodiversity index remote sensing data product pre-Black Sea region of the Ukraine web service

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

在线全文

维普期刊数据库

学校读者我要写书评

暂无评论

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)

Physiological strategies in wild rodents:immune defenses of commensal rats

在线全文

学校读者我要写书评

暂无评论

Integrative Zoology 2024年第3期19卷 350-370页

作者： Ivana MIRKOV Dina TUCOVIC Jelena KULAS Anastasija MALESEVIC Dragan KATARANOVSKI Milena KATARANOVSKI Aleksandra.popov ALEKSANDROV Immunotoxicology Group Department of EcologyInstitute for Biological Research“Sinisa Stankovic”—National Institute of Republic of SerbiaUniversity of BelgradeBelgradeSerbia

The importance of issues associated with urban/commensal rats and mice(property damage,management costs,and health risks)press upon research on these animals.While the demography of commensal rodents is mostly studied,the need for understanding factors influencing their natural morbidity/mortality is also stressed.In this respect,more attention is expected to be paid to immunity,the physiological mechanism of defense against host survival threats(pathogens,parasites,diseases).Commensal rats and mice carry numerous pathogens that evoke diverse immune responses.The state of immunity in commensal house mice is studied in great detail,owing to the use of laboratory strains in biomedical research.Because commensal rats are,compared to mice,carriers of more zoonotic agents,rats’immunity is studied mainly in that context.Some of these zoonotic agents cause chronic,asymptomatic infections,which justified studies of immunological mechanisms of pathogen tolerance versus clearance regulation in rats.Occurrence of some infections in specific tissues/organs pressed upon analysis of local/regional immune responses and/or immunopathology.A survey of immunological activity/responses in commensal rats is given in this review,with mention of existing data in commensal mice.It should throw some light on the factors relevant to their morbidity and lifespan,supplementing the knowledge of commensal rodent ecology.

关键词： commensal rats and mice immunopathology infection inflammation tolerance

Atherosclerosis originating from childhood:Specific features

在线全文

维普期刊数据库

学校读者我要写书评

暂无评论

Journal of Biomedical Research 2024年第3期38卷 233-240页

作者： Anastasia V.Poznyak Alexey A.Yakovlev MikhailА.popov Elena B.Zhigmitova Vasily N.Sukhorukov Alexander N.Orekhov Institute for Atherosclerosis Research Moscow 121609Russia Federal Research and Clinical Center of Intensive Care Medicine and Rehabilitology Moscow 109240Russia Department of Cardiac Surgery Moscow Regional Research and Clinical InstituteMoscow 129110Russia Laboratory of Angiopathology Institute of General Pathology and PathophysiologyMoscow 125315Russia

Atherosclerosis is extremely widespread.Traditionally,it is considered a disease of older people,who most often experience problems with the heart and blood vessels.While much attention from the scientific community has been paid to studying the association between aging and atherosclerosis,as well as its consequences,there is evidence that atherosclerosis occurs at an early age.Atherosclerosis may form both during intrauterine development and in childhood.Nutrition plays an important role in childhood atherosclerosis,along with previous infectious diseases and excess weight of both the child and the mother.In the present review,we examined the development of atherosclerosis and the prerequisites in childhood.

关键词： atherosclerosis childhood pediatrics cardiovascular disease

对竞技游泳训练手段方法的演变及与游泳记录提高规律的探讨

在线全文

学校读者我要写书评

暂无评论

游泳季刊 1997年第4期 3-6页

作者：阿.弗.波波夫塔兰帕尔蒂卡迟爱光俄罗斯公用事业科学院俄罗斯国立体育科学院

在训练手段、训练方法和训练条件的作用下,由于运动员适应能力的不断提高,致使游泳世界纪录也在不断提高。在周期性运动项目中,国际比赛条件标准化程度极高,所以通过对世界纪录提高规律的探讨,有助于了解不同训练方法的作用特点,同时有... 详细信息

在训练手段、训练方法和训练条件的作用下,由于运动员适应能力的不断提高,致使游泳世界纪录也在不断提高。在周期性运动项目中,国际比赛条件标准化程度极高,所以通过对世界纪录提高规律的探讨,有助于了解不同训练方法的作用特点,同时有助于预测训练理论与方法的发展方向。在本课题研究过程中,通过文献分析、查阅世界优秀运动员的训练日记、对这些运动员进行咨询等方法,对世界优秀游泳运动员(奥运会冠军和奖牌获得者,世界和欧洲纪录保持者)

关键词： sports swimming contemporary century technique training means methodology of coaching ergogenic aids world records dynamics