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Research in Astronomy and Astrophysics 2016年第9期16卷 15-22页

作者： Diana petrova Kiurkchieva Velimir Angelov Popov Doroteya Lyubenova Vasileva nikola ivanov petrov Department of Physics Shumen University115Universitetska Str.1712 ShumenBulgaria IRIDA Observatory 17A Prof.Asen Zlatarov Str.SofiaBulgaria Institute of Astronomy and National Astronomical Observatory Bulgarian Academy of Sciences72Tsarigradsko Shose Blvd.1784 SofiaBulgaria

Photometric observations in Sloan 9＇ and i＇ bands of four W UMa stars, NSVS 2244206, NSVS 908513, CSS J004004.7＋385531 and VSX J062624.4＋570907, are presented. The light curve solutions reveal that all targets have overcontact configurations with fillout factors within 0.15-0.26. Their components are G-K spectral types and are almost in thermal contact. They are also relatively close in size and luminosity： the radius ratios r2/r1 are within 0.75-0.90; the luminosity ratios 12/11 are within 0.53-0.63. The results of the light curve solution of CSS J004004.7＋385531 imply the weak limb-darkening effect of its primary component and possible presence of additional absorbing features in the system.

关键词： methods data analysis -- stars fundamental parameters -- stars binaries eclipsing individ-ual (NSVS 2244206, NSVS 908513, CSS J004004.7+385531, VSX J062624.4+570907)

Observations and light curve solutions of a selection of middle-contact W UMa binaries

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Research in Astronomy and Astrophysics 2018年第4期18卷 105-114页

作者： Diana petrova Kjurkchieva Velimir Angelov Popov Doroteya Lyubenova Vasileva nikola ivanov petrov Department of Physics Shumen University IRIDA Observatory Rozhen NAO Institute of Astronomy and NAO Bulgarian Academy of Sciences

Photometric observations in Sloan g′and i′ bands of W UMa binaries NSVS 4340949,T-Dra0–00959,GSC 03950–00707,NSVS 4665041,NSVS 4803568,MM Peg,MM Com and NSVS4751449 are *** light curve solutions revealed that the components of each target are of G and K spectral *** binaries of the sample have middle-contact configurations whose fillout factors are within the range 0.2–*** only exception is NSVS 4751449 which is in deeper contact（fillout factor of 0.55）.It precisely obeys the relation between mass ratio and fillout factor for deep,low mass ratio overcontact *** of the eclipses of almost all targets（except MM Peg）is an occultation and their photometric mass ratios and solutions could be accepted with *** found that the target components have almost equal temperatures but differ considerably in size and *** components of the partially-eclipsed MM Peg have close *** solutions reveal that NSVS 4340949,T-Dra0–00959,NSVS 4803568 and MM Com are of W subtype while GSC 03950–00707,NSVS 4665041,MM Peg and NSVS 4751449 are of A *** subclassification is well-determined for all totallyeclipsed *** targets confirm the trends in which W-subtype systems have smaller periods and lower temperatures than A subtype binaries.

关键词： binaries close — binaries eclipsing — stars fundamental parameters — stars late-type

Observations and light curve solutions of the W UMa binaries V796 Cep,V797 Cep,CSS J015341.9+381641 and NSVS 3853195

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Research in Astronomy and Astrophysics 2017年第5期17卷 31-38页

作者： Diana petrova Kjurkchieva Velimir Angelov Popov Sunay Ibryamov Ibryamov Doroteya Lyubenova Vasileva nikola ivanov petrov Department of Physics Shumen University115 Universitetska Str.9712 ShumenBulgaria IRIDA Observatory Rozhen NAOBulgaria Institute of Astronomy and NAO Bulgarian Academy of Sciences72 Tsarigradsko Shose Blvd.1784 SofiaBulgaria

Photometric observations in Sloan g′and i′bands of four W UMa binaries, V796 Cep,V797 Cep, CSS J015341.9＋381641 and NSVS 3853195, are presented. Our observations showed that CSS J015404.1＋382805 and NSVS 3853195 are the same star. We determined the initial epochs T_0 of all targets and found improved values for the period of NSVS 3853195. The light curve solutions of our data revealed that the components of each target are almost the same in terms of mass, temperature,radius and luminosity. The stellar components are G and K spectral types and undergo partial *** systems have barely-overcontact configurations and can be classified as H subtype W UMa *** established that the relation between the luminosity ratio l_2/l_1 and mass ratio q of our targets is approximately l_2/l_1 = q^（1.5）.

关键词： stars: binaries: eclipsing -- stars: fundamental parameters -- stars: individual (V796 Cep,V797 Cep CSS J015341.9+381641 NSVS 3853195)

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)

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)

V2551 Cyg:a pulsating star with enigmatic peculiarities

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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 *** 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)

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)

Epidemic Outbreaks in Plovdiv Region (Bulgaria) of Vaccine-Preventable Diseases: Measles, Mumps, Hepatitis A

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World Journal of Vaccines 2012年第3期2卷 172-177页

作者： nikolay Todorov Vatev Mariyana Vartigova Stoycheva Andrei ivanov petrov Rayna Dimitrova Velcheva Medical University-Plovdiv Dept. Hygiene Ecology and Epidemiology Plovdiv Bulgaria Medical University-Plovdiv Dept. Infectious Diseases Parasitology and Tropical Medicine Plovdiv Bulgaria

Aim: To analyze the reasons for epidemic outbreaks of measles, mumps and viral hepatitis A and to propose measures to prevent them in future. Materials and methods: Тhe incidence of measles, mumps and hepatitis A in Plovdiv region was studied for the period 2006-2010. An analysis of the age structure of the patients was made, while taking into account the time for routine immunization performed against measles and mumps (first and second dose). Results: In 2006-2009 single cases of measles were found occasionally, but in 2010 they were 2787 (incidence 395/100,000). Most of them (51%) were for ages 13 months-12years, 27%-0-13 months and 11%-13 to 18 years. The incidence of mumps for 2006-2010 varied widely, and has increased significantly in 2007 (130/100,000) and 2008 (169/100,000). The majority of patients (over 34%) during the epidemics were aged 13 months-12years, and over 26% of them-13-19 years. For the period 2006-2010 the incidence of hepatitis A ranged from 2.98/100, 000 (2009) to 426/100,000 (2006). Over 50% of the cases involved children aged up to 9 years. For the three diseases over 80% of patients were individuals of Roma origin. Conclusions: 1. Epidemic spread of measles in 2010 was mainly due to shortcomings in the routine immunization carried as a prevention of the disease. 2. There are two reasons for the outbreak of mumps: А) Failure to administer the second vaccine dose at 12 years in Bulgaria until 2001. B) Shortcomings in routinely performed immunization. 3. The extremely high incidence of hepatitis A in 2006 (and in the rest of the years) is due to the lack of routine immunization. 4. Essential for the outbreaks in all three diseases are the poor hygienic living conditions, the low social status and the lack of health promotion of the population at risk 5. To prevent future outbreaks of the diseases hereby in question, we suggest it is appropriate: А) To introduce compulsory immunization against hepatitis A;B) To carry out periodic catch-up vac

关键词： Vaccine Preventable Diseases Measles Mumps Hepatitis A Outbreaks

Image Processing Tool Promoting Decision-Making in Liver Surgery of Patients with Chronic Kidney Disease

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Journal of Software Engineering and Applications 2014年第2期7卷 118-127页

作者： Kristina Bliznakova nikola Kolev Zhivko Bliznakov Ivan Buliev Anton Tonev Elitsa Encheva Krasimir ivanov Department of Electronics and Microelectronics Technical University of Varna Varna Bulgaria Department of Medical Physics University of Patras Patras Greece Department of Radiology Medical University of Varna Varna Bulgaria Department of Surgery Medical University of Varna Varna Bulgaria

Preoperative assessment of the liver volume and function of the remnant liver is a mandatory prerequisite before performing major hepatectomy. The aim of this work is to develop and test a software application for evaluation of the residual function of the liver prior to the intervention of the surgeons. For this purpose, a complete software platform consisting of three basic modules: liver volume segmentation, visualization, and virtual cutting, was developed and tested. Liver volume segmentation is based on a patient examination with non-contrast abdominal Computed Tomography (CT). The basis of the segmentation is a multiple seeded region growing algorithm adapted for use with CT images without contrast-enhancement. Virtual tumor resection is performed interactively by outlining the liver region on the CT images. The software application then processes the results to produce a three-dimensional (3D) image of the “resected” region. Finally, 3D rendering module provides possibility for easy and fast interpretation of the segmentation results. The visual outputs are accompanied with quantitative measures that further provide estimation of the residual liver function and based on them the surgeons could make a better decision. The developed system was tested and verified with twenty abdominal CT patient sets consisting of different numbers of tomographic images. Volumes, obtained by manual tracing of two surgeon experts, showed a mean relative difference of 4.5%. The application was used in a study that demonstrates the need and the added value of such a tool in practice and in education.

关键词： Non-Contrast Enhanced Computed Tomography Images Evaluation of the Residual Function of the Liver Liver Segmentation Seeded Regional Growing Algorithm Virtual Tumor Resection Decision-Making Educational Tool

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空气-等离子镀覆技术的进展

热处理 2014年第1期29卷 8-14页

作者： В.Я.Фролов Г.К.Петров Б.А.Юшин Д.В.Иванов СПбГПУ г.Санкт-Петербург

空气-等离子喷涂工艺在许多领域得到了应用。近年来,国立圣彼得堡综合技术大学在等离子体发生器的创建和涂覆工艺方面进行了研究,业已研制成多种涂层,既可用于新制零件的防护,也可用于磨损件的修复。国立圣彼得堡综合技术大学和雷波尼茨... 详细信息

空气-等离子喷涂工艺在许多领域得到了应用。近年来,国立圣彼得堡综合技术大学在等离子体发生器的创建和涂覆工艺方面进行了研究,业已研制成多种涂层,既可用于新制零件的防护,也可用于磨损件的修复。国立圣彼得堡综合技术大学和雷波尼茨(INP Greifswald)等离子体及工艺研究院联合进行的理论和试验研究,可显著减少研发等离子体发生器和空气-等离子涂覆工艺的试验工作量。

关键词：空气-电弧涂覆电弧等离子体发生器耐磨涂层修复涂层耐蚀涂层绝热涂层绝缘涂层保护-装饰涂层