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ON APPROXIMATION OF SMOOTH FUNCTIONS FROM NULL SPACES OF OPTIMAL LINEAR DIFFERENTIAL OPERATORS WITH CONSTANT COEFFICIENTS

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Analysis in Theory and Applications 2011年第2期27卷 187-200页

作者： vesselin Vatchev University of Texas at Brownsville

For a real valued function f defined on a finite interval I we consider the problem of approximating f from null spaces of differential operators of the form Ln（ψ） =∑k=0^n akψ（k） where the constant coefficients... 详细信息

关键词： approximation of analytic function differential operator fundamental set of solutions

Hybrid model for prediction of welding distortions in large structures

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Frontiers of Materials Science 2011年第2期5卷 209-215页

作者： vesselin MICHAILOV Nikolay DOYNOV Christoph STAPELFELD Ralf OSSENBRINK Chair of Joining and Welding Technology Brandenburg Technical University of Cottbus Konrad-Wachsmann-Allee 17 03046 Cottbus Germany

The paper presents a short overview of the contemporary approaches for calculating welding distortions. In order to meet the existing challenges, an advanced hybrid model for prediction of welding distortions in large structures is described. For the purpose of illustrating the capability of this model, a simulation case is put into discussion. The results are validated by comparison with experimental data, as well as with common simulation technique. Analysis of the calculation costs is also presented. The directions for development of calculation technique, based on the presented model, are also suggested.

关键词： hybrid model welding distortion calculation

Process Philosophical Adventures of Applied Ontology

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Journal of Philosophy Study 2016年第1期6卷 26-33页

作者： vesselin Petrov Bulgarian Academy of Sciences

The paper is devoted to the new sphere of applied process ontology. It first makes a short review of the recent investigations in that area. Then it stresses on the importance of applied process ontology. Next the main methodological approaches of applied process ontology are considered： the ＂top down＂ and ＂bottom up＂ approaches. It is argued about the necessity and fruitfulness to combine both ＂top down＂ and ＂bottom up＂ approaches, and not to rely on one of them only. An example is given of the important role of process ontology as general methodological framework for the building up of regional formal ontology. Finally, the idea of variable ontological categories is stressed on and argued for its fruitfulness.

关键词： applied ontology applied process ontology methodological framework of ontology regional ontology,ontology as philosophy ontology as technology variable ontological categories

Fabrication and study of supercapacitor electrodes based on oxygen plasma functionalized carbon nanotube fibers

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Journal of Energy Chemistry 2020年第1期29卷 120-131,I0005页

作者： Paa Kwasi Adusei Seyram Gbordzoe Sathya Narayan Kanakaraj Yu-Yun Hsieh Noe T.Alvarez Yanbo Fang Kevin Johnson Colin McConnell vesselin Shanov Department of Mechanical and Materials Engineering University of CincinnatiCincinnatiOH 45221-0072USA Department of Chemical and Environmental Engineering University of CincinnatiOH 45221-0012USA Department of Chemistry University of CincinnatiOH 45221-0172USA

Dry-spun Carbon Nanotube(CNT)fibers were surface-modified by atmospheric pressure oxygen plasma functionalization using a well controlled and continuous *** fibers were characterized by scanning electron microscopy(SEM),Raman spectroscopy,and X-ray Photoelectron Spectroscopy(XPS).It was found from the conducted electrochemical measurements that the functionalized fibers showed a 132.8% increase in specific capacitance compared to non-functionalized ***-adsorption test and the obtained Randles-Sevcik plot demonstrated that the oxygen plasma functionalized fibers exhibited increased surface *** was further established by Brunauer-Emmett-Teller(BET)measurements that the surface area of the CNT fibers was increased from 168.22 m^2/g to 208.01 m^2/g after plasma *** pore size distribution of the fibers was also altered by this *** improved electrochemical data was attributed to enhanced wettability,increased surface area,and the presence of oxygen functional groups,which promoted the capacitance of the *** supercapacitors were fabricated from the oxygen plasma functionalized CNT fiber electrodes using different electrolyte *** devices with functionalized electrodes exhibited excellent cyclic stability(93.2% after 4000 cycles),flexibility,bendability,and good energy *** 0.5 m A/cm^2,the EMIMBF4 device revealed a specific capacitance,which is 27% and 65%greater than the specific capacitances of devices using EMIMTFSI and H2SO4 electrolytes,*** practiced in this work plasma surface processing can be employed in other applications where fibers,yarns,ribbons,and sheets need to be chemically modified.

关键词： Oxygen plasma functionalization Fiber supercapacitors CNT fiber electrodes Ionic liquid

Preliminary study on modelling, fabrication by photo-chemical etching and in vivo testing of biodegradable magnesium AZ31 stents

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Bioactive Materials 2021年第6期6卷 1663-1675页

作者： Bala Subramanya Pavan Kumar Kandala Guangqi Zhang Capucine LCorriveau Mark Paquin Madeleine Chagnon Dana Begun vesselin Shanov Department of Mechanical and Materials Engineering University of CincinnatiOH45221USA Department of Chemical and Environmental Engineering University of CincinnatiOH45221USA Charles River Laboratories Montreal ULC BoisbriandQuebecJ7H 1N8Canada Medical Products Market Consulting IncIndianapolisIN46202USA Waygate Technologies Baker HughesCincinnatiOH45241USA

Magnesium metal(Mg)is a promising material for stent applications due to its biocompatibility and ability to be resorbed by the *** of stents by laser cutting has become an industry *** alternative approach uses photo-chemical etching to transfer a pattern of the stent onto a Mg *** this study,we present three stages of creating and validating a stent prototype,which includes design and simulation using finite element analysis(FEA),followed by fabrication based on AZ31 alloy and,finally,in vivo testing in peripheral arteries of domestic *** to the preliminary character of this study,only six stents were implanted in two domestic farm pigs weighing 25-28 kg and they were evaluated after 28 days,with an interim follow-up on day *** left and right superficial femoral,the left iliac,and the right renal artery were selected for this *** diameters of the stented artery segments were evaluated at the time of implantation,on day 14 and then,finally,on day 28,by quantitative vessel analysis(QVA)using fluoroscopic *** Coherence Tomography(OCT)imaging displayed some malposition,breaks,stacking,and protrusion into the lumen at the proximal,distal,and mid-sections of the stented *** stents degraded with time,but simultaneously became embedded in the *** 28 days,the animals were euthanized,and explanted vessels were fixed for micro-CT imaging and histology ***-CT imaging revealed stent morphological and volumetric changes due to the in-body *** in vivo corrosion rate of 0.75 mm/year was obtained by the CT *** histology suggested no-life threatening effects,although moderate injury,inflammation,and endothelialization scores were observed.

关键词： Magnesium alloy FEA modelling Stents Photo-chemically etching Micro-CT Histology

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核结构模型中的两体以上相互作用（英文）

原子核物理评论 2017年第1期34卷 105-109页

作者： vesselin G.Gueorguiev 前沿物理研究院保加利亚索菲亚1618 四川大学匹兹堡学院中国成都610207

讨论了核结构模型中两体以上相互作用的可能形式。首先以基于手征微扰论并适于描述轻核的三体接触型相互作用为例,讨论了能合理描述~3H和~3He结合能的三核子接触型相互作用相关的两个低能有效耦合参数cD和cE间的关系并通过4He结合能给... 详细信息

讨论了核结构模型中两体以上相互作用的可能形式。首先以基于手征微扰论并适于描述轻核的三体接触型相互作用为例,讨论了能合理描述~3H和~3He结合能的三核子接触型相互作用相关的两个低能有效耦合参数cD和cE间的关系并通过4He结合能给出了相应的物理参数区。其次通过Okubo-Lee-Suzuzki有效相互作用方法对核多体问题在有限模型空间的求解,论证了A-体相互作用项。最后利用包含了A-体推广对力的可解模型对重核的同位素长链进行了分析。以132Sn为核芯,通过对Sn同位素链的计算揭示了推广对力参数G(A)与模型价核子空间维数dim(A)间的显著关系:G(A)=259.436 dim(A)-0.9985。这些分析结果说明,有必要对核中经手征微扰论或其它唯象理论所得到的NNN-,NNNN-,及A-体相互作用作进一步的研究。

关键词：核相互作用 A-体相互作用严格可解模型

Analytical-Numerical Modeling Approach for Calculation of the Structural Distortions after Welding and Thermal Straightening

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Journal of Mechanics Engineering and Automation 2016年第5期6卷 246-253页

作者： vesselin G. Michailov Nikolay Doynov Department Joining and Welding Technology Brandenburg University of Technology Cottbus 03046 Germany

The analytic-numerical hybrid model for calculating welding distortions in large welded structures is presented. Objective of the analytical model is the calculation of the plastic strains and their distribution after welding and thermal straightening process. The consideration of the essential physical relations is put into discussion. Afterwards the obtained plastic strains by the analytical calculation are loaded on an elastic FE-model of the structure and the distortions of the whole structure are predicted. The consideration of welding and thermal straightening scenarios and the assembling stages is done by taking into account the intermediate variation of the strain state at every processing step. The model is intended to be used for solving industrial tasks, i.e. intending acceptable precision and calculation time as well as low simulation costs. The application of the model is demonstrated on structures with many welds and straightening spots.

关键词： Computational welding mechanics welding distortions thermal straightening.

Energy Spectrum of Linear Internal Wave Field in the Vicinity of Continental Slope

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Journal of Applied Mathematics and Physics 2020年第10期8卷 2256-2274页

作者： Ranis N. Ibragimov Austin Biondi Nathan Arndt Maria Castillo Guang Lin vesselin Vatchev Sheng Zhang Wenatchee Valley College Wenatchee WA USA University of Wisconsin-Parkside Kenosha WI USA Purdue University West Lafayette IN USA University of Texas Rio Grande Edinburg TX USA

The purpose of the research was to investigate two-dimensional modeling of efficiency of mixing, resulting from the reflection of a linear internal wave field (IWF) off a continental slope. Efficiency of deep ocean mixing was associated with the energy balance of the radiating IWF into an interior of the ocean in the vicinity of a sloping bottom topography. Since waves are generated not only at the fundamental frequency but also at all of its harmonics ωn = nω less than buoyancy frequency N and greater than Coriolis frequency f, our analysis includes, in general, an infinite number of discrete internal wave modes n satisfying the dispersion relationship for internal waves. However, since we are interested only in the radiating part of the field, the mode numbers are limited. Due to multiple singularities of order two caused by resonance in the vicinity of critical slope, the energy is visualized in Lδ -norm with δ > 2. Research results include the visualization of the effects of the continental slope and the Earth’s rotation on resulting energy in the vicinity of the slope.

关键词： Internal Wave Field Effects of Rotation Continental Slope Energy Radiation

Assessing Drought Vulnerability of Bulgarian Agriculture through Model Simulations

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Journal of Environmental Science and Engineering(B) 2012年第8期1卷 1017-1036页

作者： Zomitsa Popova Maria Ivanova Luis Santos Pereira vesselin Alexandrov Katerina Doneva Petra Alexandrova Milena Kercheva N. Poushkarov Institute of Soil Scienee-lSSNP Sofia 1080 Bulgaria CEER-Biosystems Engineering Institute of Agronomy Technical University of Lisbon Tapada da Ajuda Lisboa 1349-017Portugal National Institute of Meteorology and Hydrology-NIMH Sofia 1784 Bulgaria

This study assesses vulnerability of agriculture to drought, using WINISAREG model and seasonal SPI2-index for eight climate regions （1951-2004）. Results relative to Plovdiv show that in soils of large TAW （total available water） net irrigation requirements NIRs range from 0 to 380 mm. In soils of small TAW, NIRs reach 440 mm in the very dry year. NIRs in Sofia/Silistra are about 100 mm smaller than in Plovdiv while in Sandanski they are 30-110 mm larger. Rainfed maize is associated with great yield variability （29% 〈 Cv 〈 72%）. Considering an economical RYD （relative yield decrease） threshold, 32% of years are risky when TA Wis large in Plovdiv that is double than in Sofia and half than in Sandanski. In North Bulgaria the risky years are 10% in Pleven/Silistra that is half than in Lom. In Plovdiv region reliable relationships （R2 〉 91%） were found relating the SPI2 ＂July-Aug.＂ with simulated RYD of rainfed maize while remaining relationships were less accurate （73% 〈 R2 〈 86%）. Economical losses are produced when High Peak Season SPI2 〈＋ 0.20 in Sandanski, SPI2 〈 - 0.50 in Plovdiv and SPI2 〈 - 0.90 in Sofia. In North Bulgaria the SPI2 threshold ranges from - 0.75 to - 1.50. Derived reliable relationships and SPl-thresholds are used for drought vulnerability mapping.

关键词： Drought vulnerability maize ISAREG simulation model SPI-index drought vulnerability mapping.