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Cyclic posets and triangulation clusters

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Science China Mathematics 2019年第7期62卷 1289-1316页

作者： Kiyoshi Igusa Gordana todorov Department of Mathematics Brandeis University Waltham MA 02454 USA Department of Mathematics Northeastern University Boston MA 02115 USA

Triangulated categories coming from cyclic posets were originally introduced by the authors in a previous paper as a generalization of the constructions of various triangulated categories with cluster *** give an overview, and then analyze "triangulation clusters" which are those corresponding to topological triangulations of the 2-disk. Locally finite nontriangulation clusters give topological triangulations of the "cactus space" associated to the "cactus cyclic poset".

关键词： cactus cyclic poset cluster structure triangulated categories Frobenius categories cocycle

Fractionation and Soil-Plant Transfer of ^(241)Am in Different Soil Types

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Pedosphere 2015年第2期25卷 212-219页

作者： Boyan todorov Rumyana DJINGOVA Faculty of Chemistry and Pharmacy University of Sofia

Monitoring the behavior of radioactive contaminants associated with military applications,nuclear power facilities,and interim storage of radioactive waste materials is of significant concern in radiological *** sequential extraction schemes(SES) for fractionation of ^(241)Am were compared using five different types of soils,Vertisol,Cambisol,Chromic Luvisol,Eutric Fluvisol,and mixed urban soil,collected from different parts of *** results for the exchangeable ^(241) Am were in a wide range and depended on the SES *** ^(241)Am varied from 0.5%to 6%in the exchangeable phase,from 0.5%to 35%in the carbonate phase,from0.4%to 36%in the reducible phase(easily reducible and moderately reducible),from 3%to 17%in the oxidizable phase,and from10%to 50%in the residual *** 100 d of contamination,around 50%of soil ^(241)Am was permanently fixed in the residual *** was strong evidence that the preferable soil phase for ^(241) Am was the carbonate *** transfer factor of ^(241) Am in the soil-plant system depended on ^(241)Am in the easily oxidizable phase(fulvic acid(FA)+humic acid(HA) phase).These confirmed the applicability of the National Institute of Standards and Technology(NIST) sequential extraction scheme for fractionation of soil^(241) Am since it includes extraction of FA+HA phase and then the carbonate phase.

关键词： carbonate fulvic acid humic acid radioactive contaminants sequential extraction scheme soil contamination transfer factor

Moving least-squares approximations for linearly-solvable stochastic optimal control problems

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控制理论与应用（英文版） 2011年第3期9卷 451-463页

作者： Mingyuan Zhong Emanuel todorov Department of Applied Mathematics University of Washington Seattle USA Department of Computer Science University of Washington Seattle USA

Nonlinear stochastic optimal control problems are fundamental in control theory.A general class of such problems can be reduced to computing the principal eigenfunction of a linear ***,we describe a new method for finding this eigenfunction using a moving least-squares function *** use efficient iterative solvers that do not require matrix factorization,thereby allowing us to handle large numbers of basis *** bases are evaluated at collocation states that change over iterations of the algorithm,so as to provide higher resolution at the regions of state space that are visited more *** shape of the bases is automatically defined given the collocation states,in a way that avoids gaps in the *** results on test problems are provided.

关键词： Stochastic optimal control Bellman equations

Method for Tentative Evaluation of Membrane Permeability Coefficients for Sodium and Potassium Ions in Unicellular Organisms

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Open Journal of Biophysics 2013年第1期3卷 91-98页

作者： Atanas todorov Atanasov Department of Physics and Biophysics Medical Faculty Trakia University Stara Zagora Bulgaria

The membrane permeability coefficient for sodium and potassium ions in unicellular organisms can be calculated using the data for cell volume, surface and mean generation time during growth and dividing of cells by binary. Accordingly theory of proposed method, the membrane permeability coefficients for passed trough outer cell membrane sodium and potassium ions, is equal to the volume of unicellular organism divided to product between cell surface and mean generation time of cells. The calculated by this way diapason of values overlaps with experimentally measured diapason of values of permeability coefficient for sodium and potassium ions. The deviation between the theoretically calculated and experimentally measured values of permeability coefficient does not exceed one order of magnitude.

关键词： Prokaryotes Eukaryotes Permeability Coefficient Sodium Potassium Ion

Nasal Cycle Dilemma: Nasal Cycle Is Associated to Brain Wake/REM States or Is Associated to Conscious State in Them?

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Open Journal of Biophysics 2019年第1期9卷 1-9页

作者： Atanas todorov Atanasov Department of Physics and Biophysics Medical Faculty Trakia University Stara Zagora Bulgaria

Experimental and theoretical arguments have been described in favor of the hypothesis that the nasal cycle reversals of the nostril’s airflow occurs only in the consciousness states of the brain (during awake/wake state, REM state and during dreams in St.1, 2 of the non-REM sleep). This finding gives possibility to use nasal cycle as “marker for consciousness states”. An idea for clinical application of the hypothesis is proposed.

关键词： Nasal Cycle Sleep Cycle Consciousness EEG Waves

Length of Periods in the Nasal Cycle during 24-Hours Registration

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Open Journal of Biophysics 2014年第3期4卷 93-96页

作者： Atanas todorov Atanasov Department of Physics and Biophysics Medical Faculty Trakia University Stara Zagora Bulgaria

The periodic congestion and decongestion of the nasal venous sinuses and an alternation of airflow from one side of the nose to the other are known in literature as “nasal cycle”. It is established that nasal cycle during 24-hours registration contains from 4 to 8 time full periods, length of which varies from 0.80 h to 5.75 h. The mean length of all full periods is 2.80 ± 0.17 h. The mean length of full periods of left nostril is 3.07 h and the mean length of periods of right nostril is 2.43 h. The result suggests that there is any asymmetry in length of periods of airflow trough left and right nostrils about 40 min. The longer periods of left nostril can be connected with higher metabolic and functional activity of brain and human organism during active work.

关键词： Nasal Cycle Periods of Nostril Sleep Cycle

Study the Influence of a Gap between the Wing and Slotted Flap over the Aerodynamic Characteristics of Ultra-Light Aircraft Wing Airfoil

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Journal of Mechanics Engineering and Automation 2015年第5期5卷 278-285页

作者： Cvetelina Velkova Michael todorov Guillaume Durand Department of Mechanics Faculty of Transport Technical University Sofia 1000 Bulgaria ECAM Strasbourg-Europe 2 rue de Madrid - 67300 Schiltigheim France

The purpose of the study is to assess what the influence of the distance of the gap is between the wing and slotted flap on the aerodynamic characteristics of ultra-light aircraft wing when the flap is retracted. It has been elected numerical approach to the study and it is been realized through applied numerical model of the wing airfoil NACA 2412 for three different lengths of slotted gap size, whose length is expressed as percentages of the airfoil chord. The code ANSYS FLUENT has been applied, as it has been determined RANS （Reynolds-averaged Navier-Stokes） equations and DES （detached-eddy simulation） turbulent model has been used.

关键词： Aerodynamics wing airfoil slotted flap gap numerical approach.

Lexicographic Constant-Weight Equidistant Codes over the Alphabet of Three, Four and Five Elements

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Intelligent Information Management 2010年第3期2卷 183-187页

作者： Todor todorov Galina Bogdanova Teodora Yorgova 不详

In this paper we consider the problem of finding bounds on the size of lexicographic constant-weight equidistant codes over the alphabet of three, four and five elements with 2 ≤ w 详细信息

In this paper we consider the problem of finding bounds on the size of lexicographic constant-weight equidistant codes over the alphabet of three, four and five elements with 2 ≤ w

关键词： Lexicographic Codes Equidistant Codes Constant-Weight Codes Bounds of Codes

Drivers for High Power Laser Diodes

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光机电信息 2006年第6期23卷 23-27页

作者： Yankov P todorov D Saramov E Technical University Sofia Kl.Ohridski Blvd 81719 SofiaBulgaria Technical University Sofia

During the last year the high power laser diodes jumped over the 1 kW level of CW power for a stack, and the commercial 1 cm bars reached 100 W output optical power at the standard wavelengths around 800 nm and 980 nm. The prices are reaching the industry acceptable levels. All Nd∶YAG and fiber industrial lasers manufacturers have developed kW prototypes. Those achievements have set new requirements for the power supplies manufactuers-high and stable output current, and possibilities for fast control of the driving current, keeping safe the expensive laser diode. The fast switching frequencies also allow long range free space communications and optical range finding. The high frequencies allow the design of a 3D laser radar with high resolution and other military applications. The prospects for direct laser diode micro machining are also attractive.

关键词：高功率激光二极管电源驱动器光学器件