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vegetation cover of the lahar valley on the Sarychev Peak volcano(Matua Isl.,Middle Kuril Islands) after the Eruption in 2009: current state and features of succession processes

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Journal of Mountain Science 2021年第7期18卷 1762-1777页

作者： fedor A.ROMANYUK Alexander v.KORDYUKOv Institute of Marine Geology and Geophysics Far East Branch Russian Academy of Sciences693022Yuzhno-SakhalinskNauki Street1bSakhalin regionRussia

The paper presents the study of the vegetation recovery after the descent of the lahar during the eruption of the Sarychev Peak volcano(Matua Isl.,Middle Kuriles) in *** works were carried out in *** was found that during the secondary succession,plant communities,typical of the altitudinal zonation of the volcanic structure vegetation,are formed on lahar sediments in the following manner: the upper sections of the slope are occupied by sparse meadow and shrub vegetation,the middle are presented by shrub belt with a developed canopy,and the lower are representative of shrub large-grass *** the same time,the ordination analysis of the vegetation cover of the lahar valley by the detrended correspondence analysis(DCA) revealed the dispersion of the counting areas along the altitudinal *** is opposite to that characteristic for both,the background communities on the slopes of the studied volcanic structure,and for communities in dynamical equilibrium of a typical altitude ***,directly correlating indicators of α-diversity of communities indicate the presence of open young communities at the stage of a complex *** the species Duschekia fruticosa which is an identifier in buried sites,forms communities in a state of dynamic equilibrium,with individuals of 40–50 years old,and at the time of the work,formed a canopy with individuals of 7–8 years old,a complete recovery of the communities of the lahar valley is possible in no less than 40 *** acquired data on the recovery of vegetation on lahar contribute to the study of succession processes in the sites located in the zone of active *** addition,in this work,for the first time,the rates of restoration of the vegetation cover following its destruction as a result of burial by lahar products,are *** specific features of this process are also *** the broad range of mathematical methods for quantitative analysis of indicators of young commun

关键词： Sarychev Peak volcano Lahar Plant communities Secondary succession Indirect ordination Correlation analysis Shannon-Weaver index of biodiversity Simpson S dominance

Social Choice Meets Graph Drawing: How to Get Subexponential Time Algorithms for Ranking and Drawing Problems

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Tsinghua Science and Technology 2014年第4期19卷 374-386页

作者： Henning Fernau fedor v.Fomin Daniel Lokshtanov Matthias Mnich Geevarghese Philip Saket Saurabh FB 4-Abteilung Informatikwissenschaften Universitt Trier D-54286 TrierGermany the Department of Informatics University of Bergen N-5020 Bergen Norway Max-Planck-Institut fr Informatik D-66123 Saarbrcken Germany the Institute of Mathematical Sciences Chennai - 600113 India

We analyze a common feature of p-Kemeny AGGregation（p-KAGG） and p-One-Sided Crossing Minimization（p-OSCM） to provide new insights and findings of interest to both the graph drawing community and the social choice community. We obtain parameterized subexponential-time algorithms for p-KAGG—a problem in social choice theory—and for p-OSCM—a problem in graph drawing. These algorithms run in time O＊（2O（√k log k））,where k is the parameter, and significantly improve the previous best algorithms with running times O.1.403k/and O.1.4656k/, respectively. We also study natural ＂above-guarantee＂ versions of these problems and show them to be fixed parameter tractable. In fact, we show that the above-guarantee versions of these problems are equivalent to a weighted variant of p-directed feedback arc set. Our results for the above-guarantee version of p-KAGG reveal an interesting contrast. We show that when the number of ＂votes＂ in the input to p-KAGG is odd the above guarantee version can still be solved in time O＊（2O（√k log k））, while if it is even then the problem cannot have a subexponential time algorithm unless the exponential time hypothesis fails（equivalently, unless FPT D M[1]）.

关键词： Kemeny aggregation one-sided crossing minimization parameterized complexity subexponential-time algorithms social choice theory graph drawing directed feedback arc set

The Basic Components of Software-Hardware System for Modeling and Control of the Toroidal Plasma by Epsilon-Nets on Heterogeneous Mini-Supercomputers

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Communications in Computational Physics 2018年第6期24卷 1-26页

作者： fedor S.Zaitsev Alexei G.Shishkin Andrei A.Lukianitsa Egor P.Suchkov Sergei v.Stepanov fedor A.Anikeev Scientific Research Institute of System Development Russian Academy of SciencesNakhimovsky prosp.26 b.1117218MoscowRussia Moscow State University Department of Computational Mathematics and CyberneticsLenin’s Hills119991MoscowRussia.

A significant step towards the comprehensive solution of the important new fundamental control problems of high-temperature plasma of toroidal configuration is made by utilizing heterogeneous mini-supercomputers of NIISI RAS(Scientific Research Institute of System Development,Russian Academy of Science).The basic components of hardware and software modeling system and automatic real-time plasma feedback control are developed and *** system is named HASP CS(Hardware-Software Plasma Control System).It is based on a fundamentally new,more accurate and reliable control algorithm using a solution with a given accuracy of a number of inverse diagnostic problems by ∈-*** possibility of an application of the proposed technique during discharge time to provide feedback control of the boundary and internal plasma parameters is *** is shown that the complex allows investigating the processes in currently operated and designed fusion devices and solving problems of fusion application for energy *** recommendations to the engineering implementation of plasma control systems are *** directions for further research are formulated.

关键词： Control problem ∈-net plasma tokamak modeling

Rationality of quotients by linear actions of affine groups

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Science China Mathematics 2011年第8期54卷 1521-1532页

作者： BOGOMOLOv fedor BHNING Christian GRAF vON BOTHMER Hans-Christian Department of Mathematics Courant Institute of Mathematical Sciences New York University Mathematisches Institut University of Gottingen

LetG = SLn(C)Cn be the (special) affine group. In this paper we study the representation theory of G and in particular the question of rationality for v/G, where v is a generically free G-representation. We show that the answer to this question is positive (Theorem 6.1) if the dimension of v is sufficiently large and v is indecomposable. We explicitly characterize two-step extensions 0 → S → v → Q → 0, with completely reducible S and Q, whose rationality cannot be obtained by the methods presented here (Theorem 5.3).

关键词： rationality linear group quotients affine groups