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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)

Design of broadband terahertz vector and vortex beams: II. Holographic assessment

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Light(Advanced Manufacturing) 2022年第4期3卷 14-26页

作者： nikola. v.petrov.bogdan sokolenko Maksim S.Kulya Andrei Gorodetsky Aleksey v.Chernykh Digital and Display Holography Laboratory ITMO UniversitySt.Petersburg 197101Russia v.I.vernadsky Crimean Federal University Simferopol 295007Russia School of Physics and Astronomy University of BirminghamBirmingham B152TTUK

In this paper,we demonstrate the capabilities of the terahertz pulse time-domain holography in visualisation,simulation,and assessment of broadband THz vortex beam formation dynamics upon its shaping by elements of beam converter,and further propagation and *** adding Jones matrix formalism to describe broadband optical elements,we highlight the differences in the spatio-spectral and spatio-temporal structure of the formed vortex and vector beams dependence on the modulator used and visualise their modal *** influence of diffraction field structure from each element in the broadband vortex modulator is revealed in numerical simulation and the formed beams are analysed against the simplified Laguerre-Gaussian beam model.

关键词： Terahertz radiation vortex beams vector beams Achromatic wave plates Broadband terahertz radiation Digital holography Terahertz holography

Design of broadband terahertz vector and vortex beams: I. Review of materials and components

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Light(Advanced Manufacturing) 2022年第4期3卷 126-144页

In this paper,we review the existing approaches for vortex and vector beam shaping and generation in the terahertz frequency *** particular focus of this review is on the possibility of homogeneous topological charge formation in the ultra-wide spectral interval inherent to ultrashort terahertz *** review the available materials and components,analyse proposed and potentially possible solutions for broadband terahertz vortex and vector beam shaping,compare all developed approaches,and put forward a unified concept for constructing passive shapers of such beams from the existing component base.

关键词： Terahertz radiation vortex beams vector beams Achromatic wave plates Broadband terahertz radiation Digital holography Terahertz holography Total internal reflection Metasurface THz liquid crystals Geometric phase

Long-term forecasting of annual peak load considering effects of demand-side programs

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Journal of Modern Power Systems and Clean Energy 2018年第1期6卷 145-157页

作者： nikola.Lj.RAJAKOvIC vladimir M.SHILJKUT Faculty of Electrical Engineering University of Belgrade Public Enterprise Electric Power Industry of Serbia

The main purpose of this research paper is to investigate the long-term effects of the proposed demandside program,and its impact on annual peak load forecasting important for strategic network *** program comprises a particular set of demand-side measures aimed at reducing the annual peak *** paper also presents the program simulations for the case study of the Electricity Distribution Company of Belgrade(EDB).According to the methodology used,the first step is to determine the available controllable load of the distribution utility/area under *** controllable load is presumed constant over the analyzed time horizon,and the smart grid(SG)infrastructure *** saturation of positive effects during intense program application is also taken into *** and economic input data are taken from the real *** conducted calculations indicate that demand-side programs can bring about the same results as the energy storage in the grids with a strong impact of distributed generation from variable renewable sources(v-RES).In conclusion,the proposed demand-side program is a good alternative to building new power facilities,which can postpone investment costs for a considerable period of time.

关键词： Demand response Demand-side management Forecast Peak load Renewable energy source

Life Cycle-Stages in History of Tourism in the Republic of Macedonia

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Journal of Tourism and Hospitality Management 2017年第5期5卷 173-188页

作者： nikola.v. Dimitrov University Goce Detcev Stip Republic of Macedonia

The aim of this paper is to explore the historical development of tourism through identified stages of the life cycle （TALC） model. Many of the major destinations in the world have a far longer history and go through various successive cycles with different phases. In this article, we present the case of Macedonia, as a Balkan mainland tourist destination. The analysis is based on primary and secondary data sources for an extended period. The article shows the life cycle of the tourist destination in combination and adaptation of new TALC model that matches regulation theories and the Ford paradigm of global model for tourism development of mass production and consumption. Finally, the paper suggests and recommends practical advice aimed at motivating key players in the formation of economic policy for tourism development.

关键词： life cycle TALC model history of tourism regulation theories Ford paradigm Macedonia

Modeling challenges and potential solutions for integration of emerging DERs in DMS applications: power flow and short-circuit analysis

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Journal of Modern Power Systems and Clean Energy 2019年第6期7卷 1365-1384页

作者： Luka v.STREZOSKI nikola.R.vOJNOvIC vladimir C.STREZOSKI Predrag M.vIDOvIC Marija D.PRICA Kenneth A.LOPARO Case School of Engineering Case Western Reserve UniversityClevelandUSA Faculty of Technical Sciences University of Novi SadNovi SadSerbia

We aim to systematically review challenges imposed by emerging distributed energy resources(DERs)to model in two basic distribution management system(DMS)online applications—power flow and short-circuit analysis,as well as to offer a systematic review of potential *** the last decade,electronically coupled DERs became increasingly *** can employ a wide range of control strategies for power,current,or voltage control,in both normal and faulted ***,DERs cannot be modeled with the traditional PQ(load or generator bus)or Pv(generator bus)bus types used for modeling synchronous and induction machines in online power flow ***,since fault currents of DERs are limited to predefined maximal values,electronically coupled DERs cannot be represented with traditional voltage source behind impedance models for online short-circuit calculation(SCC).However,most of the DMS software packages still use the traditional models to represent all DER types,including those that are electronically *** paper shows that there will be large calculation errors in such practice,which make the system model an inadequate representation of the *** will lead to serious errors in the management,control,and operation of distribution ***,potential solutions to the challenges are systematically ***,the calculation results on a distribution test system with all DER types are used to prove the claim.

关键词： Distributed energy resources(DERs) Distribution management system(DMS) Power flow modeling Short-circuit modeling

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)

High-flow nasal oxygen availability for sedation decreases the use of general anesthesia during endoscopic retrograde cholangiopancreatography and endoscopic ultrasound

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World Journal of Gastroenterology 2016年第47期22卷 10398-10405页

作者： Roman Schumann nikola.S Natov Klifford A Rocuts-Martinez Matthew D Finkelman Tom v Phan Sanjay R Hegde Robert M Knapp Department of Anesthesiology and Perioperative Medicine Tufts Medical CenterBoston MA 02111United States The Gastroenterology/Hepatology Division Tufts Medical CenterBoston MA 02111United States Critical Care Medicine Dartmouth-Hitchcock Medical CenterLebanon NH 03756 United States Tufts University School of Dental Medicine Boston MA 02111United States Tufts University School of Medicine Boston MA 02111United States

AIM To examine whether high-flow nasal oxygen(HFNO) availability influences the use of general anesthesia(GA) in patients undergoing endoscopic retrograde cholangiopancreatography(ERCP) and endoscopic ultrasound(EUS) and associated *** In this retrospective study, patients were stratified into 3 eras between October 1, 2013 and June 30, 2014 based on HFNO availability for deep sedation at the time of their endoscopy. During the first and last 3-mo eras(era 1 and 3), no HFNO was available, whereas it was an option during the second 3-mo era(era 2). The primary outcome was the percent utilization of GA vs deep sedation in each period. Secondary outcomes included oxygen saturation nadir during sedation between periods, as well as procedure duration, and anesthesia-only time between periods and for GA vs sedation cases *** During the study period 238 ERCP or EUS cases were identified for analysis. Statistical testing was employed and a P vely). The oxygen saturation nadir during sedation was significantly higher in era 2 compared to era 3(P vailability was associated with decreased GA utilization and improved oxygenation for ERCP and EUS during sedation.

关键词： Endoscopic ultrasound Endoscopic retrograde cholangiopancreatography Endoscopy Sedation Anesthesia Oxygenation High flow nasal oxygen

Ultrasonic Plasma Engineering Toward Facile Synthesis of Single-Atom M-N4/N-Doped Carbon(M=Fe,Co) as Superior Oxygen Electrocatalyst in Rechargeable Zinc-Air Batteries

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Nano-Micro Letters 2021年第4期13卷 76-95页

作者： Kai Chen Seonghee Kim Minyeong Je Heechae Choi Zhicong Shi nikola.vladimir Kwang Ho Kim Oi Lun Li Department of Materials Science and Engineering Pusan National University30 Jangjeon‑dongGeumjeong‑guBusan 609‑735Republic of Korea Theoretical Materials and Chemistry Group Institute of Inorganic ChemistryUniversity of CologneGreinstr.650939 CologneGermany School of Materials and Energy Guangdong University of TechnologyGuangzhou 510006People’s Republic of China Faculty of Mechanical Engineering and Naval Architecture University of ZagrebIvana Lucica 510002 ZagrebCroatia Global Frontier R&D Center for Hybrid Interface Materials 30 Jangjeon‑dongGeumjeong‑guBusan 46241Republic of Korea

As bifunctional oxygen evolution/reduction electrocatalysts,transition-metal-based single-atom-doped nitrogen-carbon(NC)matrices are promising successors of the corresponding noblemetal-based catalysts,offering the advantages of ultrahigh atom utilization effciency and surface active ***,the fabrication of such matrices(e.g.,well-dispersed single-atom-doped M-N4/NCs)often requires numerous steps and tedious ***,ultrasonic plasma engineering allows direct carbonization in a precursor solution containing metal phthalocyanine and *** combining with the dispersion effect of ultrasonic waves,we successfully fabricated uniform single-atom M-N4(M=Fe,Co)carbon catalysts with a production rate as high as 10 mg *** Co-N4/NC presented a bifunctional potential drop ofΔE=0.79 v,outperforming the benchmark Pt/C-Ru/C catalyst(ΔE=0.88 v)at the same catalyst *** calculations revealed that Co-N4 was the major active site with superior O2 adsorption-desorption *** a practical Zn-air battery test,the air electrode coated with Co-N4/NC exhibited a specific capacity(762.8 mAh g(-1))and power density(101.62 mW cm^(-2)),exceeding those of Pt/C-Ru/C(700.8 mAh g^(-1) and 89.16 mW cm^(-2),respectively)at the same catalyst ***,for Co-N4/NC,the potential difference increased from 1.16 to 1.47 v after 100 charge-discharge *** proposed innovative and scalable strategy was concluded to be well suited for the fabrication of single-atom-doped carbons as promising bifunctional oxygen evolution/reduction electrocatalysts for metal-air batteries.

关键词： Single-atom-doped M-N4/NC catalyst Plasma engineering ORR/OER bifunctional activity DFT calculation Rechargeable Zn-air battery