Time-Optimal Gathering under Limited Visibility with One-Axis Agreement

We consider the distributed setting of N autonomous mobile robots that operate in Look-Compute-Move (LCM) cycles following the well-celebrated classic oblivious robots model. We study the fundamental problem of gathering N autonomous robots on a plane, which requires all robots to meet at a single point (or to position within a small area) that is not known beforehand. We consider limited visibility under which robots are only able to see other robots up to a constant Euclidean distance and focus on the time complexity of gathering by robots under limited visibility. There exists an O(DG) time algorithm for this problem in the fully synchronous setting, assuming that the robots agree on one coordinate axis (say north), where DG is the diameter of the visibility graph of the initial configuration. In this article, we provide the first O(DE) time algorithm for this problem in the asynchronous setting under the same assumption of robots’ agreement with one coordinate axis, where DE is the Euclidean distance between farthest-pair of robots in the initial configuration. The runtime of our algorithm is a significant improvement since for any initial configuration of N≥1 robots, DE≤DG, and there exist initial configurations for which DG can be quadratic on DE, i.e., DG=Θ(DE2). Moreover, our algorithm is asymptotically time-optimal since the trivial time lower bound for this problem is Ω(DE).

Study on Generalized Directional Differentiability Problems of Fuzzy Mappings

This paper discusses the gH-directional differentiability of fuzzy mappings, and proposes the concept of gH-directional differentiability of fuzzy mappings. Based on the concept of gH-directional differentiability of interval-valued mappings and its related properties, two properties of gH-directional differentiability fuzzy mappings are proposed. At the same time, the relation between gH-differentiability and gH-directional differentiability for a fuzzy mapping is discussed, and it is proved that both gH-derivative and gH-partial derivative are directional derivatives of fuzzy mappings in the direction of the coordinate axis.

HÀ NỘI – HUẾ – SÀI GÒN: TRỤC PHÁT TRIỂN THẲNG CỦA LỊCH SỬ ĐẤU TRANH GIẢI PHÓNG DÂN TỘC

The North–South localities-alliance movement in the particular period of the country (1954–1975) created the relationship between the three cities of Hanoi – Hue – Saigon. Historical fact shows that the relationship between the three cities has been formed and has developed for a long time. The relation axis became the rear-front coordinate axis in the period of the resistance war in modern times. In the period of peace, development, and integration, this relation axis needs to promote and expand historical values and create new practical benefits, following the axis of heritage and national security.

Dynamics of Electron in TEM Wave Field

Big amount of works deals with solution of differential equations, associated with electron motion in electromagnetic field, using methods of classical electrodynamics. Solution of equation of an electron motion in TEM wave field is interesting task because this equation is mathematical model of big number of wave processes, which are used for researches of different physical processes. The proposed work dedicated to finding the solution for the equation of an electron motion in TEM wave field in laboratory system of coordinates using the theory of almost periodic functions. The work demonstrates that the projections of electron velocity on coordinate axis conform to the wave equation, and, consequently, could be expanded into generalized Fourier series at any value of the wave and electron parameters. In the present work, the formulas received before for electron velocity projection on coordinate axis, are transformed to a well-behaved form, and are broken down into non-perfect generalized Fourier series. Non-perfect Fourier series for projections of electron velocity on coordinate axis are found by means of plotting of complex series, which are called in the theory of almost periodic functions as ”closure of set”. For approximate computation of electron velocity it is possible to restrict oneself to finite number of series harmonics. Application of method of electron velocity components transformation into generalized Fourier series made it possible to find in electron velocity components series terms, which do not depend on time and are equal to average magnitudes of the respective values. Electron velocity components present functions of initial magnitudes of electron velocity components, of generalized phase magnitude and of the wave parameters. Initial magnitudes are not preset at random, but calculated from the equations, the type of which is specified in the work. Electron trajectory in coordinate space is calculated by integrating of the respective expressions for velocity projections on coordinate axis. For demonstration purpose the work deals with the example of electron dynamics in wave polarization plane with consideration of only permanent addends and first harmonics of Fourier series for electron velocity projections on coordinate axis. An approximate solution of the equations of electron dynamics in the plane of polarization of the wave is given. Solution for the equation of electron motion in TEM wave field in the laboratory coordinate system using the theory of almost periodic functions made it possible to solve the problem of dynamics of relativistic electron in the field of progressing TEM wave. It made it possible to demonstrate the availability of time-independent summands in the value of the speed of the electron, which moves in TEM wave. A very important circumstance is also the fact, that the theory makes it possible to investigate electron dynamics depending on the original wave intensity.

УПРОВАДЖЕННЯ МОДЕЛІ ПІДГОТОВКИ МАГІСТРІВ ДО ОСВІТНЬО-НАУКОВОЇ ДІЯЛЬНОСТІ В УМОВАХ МАСОВИХ ВІДКРИТИХ ДИСТАНЦІЙНИХ КУРСІВ

The article presents the results of experimental work. It is suggested to state and analyze the results of model implementation for masters preparation to educational and scientific activity in the conditions of massive open online courses. There are indicated specialties of the future masters that took part in the experimental work, considered the list of adapted massive open online courses, in which the basis of the technologies of teaching is laid, offered the author's model. There are presented computational tables of the empirical value χ2 of the motivational, cognitive-content, reproductive and operative and productive and creative component at the beginning and at the end of the experiment in control and experimental groups, the graphic correlation on the coordinate axis of the critical and empirical values of the indicated components and the graphs of the results of the assessment of the readiness of masters educational and scientific activity in the conditions of massive open online courses at the beginning and at the end of the expedition rhythm in relative frequencies.

Infinite Multistability in a Self-Reproducing Chaotic System

Multistability exists in various regimes of dynamical systems and in different combinations, among which there is a special one generated by self-reproduction. In this paper, we describe a method for constructing self-reproducing systems from a unique class of variable-boostable systems whose coexisting attractors reside in the phase space along a specific coordinate axis and any of which can be selected by choosing an initial condition in its corresponding basin of attraction.

Graphic-Analytical Researches of Involution

Known projective transformations, namely their private types such as harmonism and involution are considered. It is known that projective transformations are collinear, at their performance the order, the cross ratio of fours of elements (on a straight line — the cross ratio of four points, in a bunch of straight lines — the cross ratio of this bunch’s four straight lines, this property (invariant) is similarly preserved for a bunch of planes, i.e. in considering of first step forms) is preserved. At a constructive approach to such transformations there are some ways for definition of position for corresponding elements which students use when studying discipline "Affine and projective geometry" on preparation profiles 09.03.01 — “CAD Systems" and 09.03.03 — “Applied Informatics in Design”. The received constructions are checked by analytical calculations, proceeding from known dependences for harmonism and involutions. In such a case results both for a range of points, and for a bunch of straight lines which pass through these points are analytically compared. The provided computational and graphic work contains three sections: prospects, harmonism and involution, and is carried out by students on individual options with application of the graphic editor Microsoft Visio or the graphic package CO MPAS voluntary. In the present paper some constructions in definition of corresponding points in elliptic and hyperbolic involution are considered, some of these constructions are published for the first time. Besides, a proposition has been formulated: in a rectangular coordinate system the work for coordinates of two points related to a circle intersection with one coordinate axis is equal to the product for coordinates of two other points related to this circle intersection with the other coordinate axis. This proposition is fairly for imaginary points of circle intersection with coordinate axes as well.