101 research outputs found
Tighter, Neater, Safer C and C++
Report published in the Proceedings of the National Conference on "Education and Research in the Information Society", Plovdiv, May, 2016Constructs are presented for alternative β tighter, neater and arguably less
vulnerable β expression of frequently occurring patterns in C and C++ programming. We find
them useful in several ways, both in teaching and in participating in programming competitions.
Working programmers can also benefit from such or similar constructs.Association for the Development of the Information Society, Institute of Mathematics and Informatics Bulgarian Academy of Sciences, Plovdiv University "Paisii Hilendarski
Spiral Walk Exposed
Report published in the Proceedings of the National Conference on "Education and Research in the Information Society", Plovdiv, May, 2015Traversing a matrix along a spiral is a popular small programming problem, but one
which is often solved incorrectly, or only partially, or in an ill-structured way. To benefit
teaching and learning good programming style, we considered worthy to present the
construction of several solutions to this problem in an expository manner. Some related
combinatorial problems are also discussed. Hopefully, the text can be useful to high and
higher school teachers and students, as well as to practicing programmers.Association for the Development of the Information Society, Institute of Mathematics and Informatics Bulgarian Academy of Sciences, Plovdiv University "Paisii Hilendarski
Chiral sedimentation of extended objects in viscous media
We study theoretically the chirality of a generic rigid object's
sedimentation in a fluid under gravity in the low Reynolds number regime. We
represent the object as a collection of small Stokes spheres or stokeslets, and
the gravitational force as a constant point force applied at an arbitrary point
of the object. For a generic configuration of stokeslets and forcing point, the
motion takes a simple form in the nearly free draining limit where the
stokeslet radius is arbitrarily small. In this case, the internal hydrodynamic
interactions between stokeslets are weak, and the object follows a helical path
while rotating at a constant angular velocity about a fixed axis. This
is independent of initial orientation, and thus constitutes a chiral
response for the object. Even though there can be no such chiral response in
the absence of hydrodynamic interactions between the stokeslets, the angular
velocity obtains a fixed, nonzero limit as the stokeslet radius approaches
zero. We characterize empirically how depends on the placement of the
stokeslets, concentrating on three-stokeslet objects with the external force
applied far from the stokeslets. Objects with the largest are aligned
along the forcing direction. In this case, the limiting varies as the
inverse square of the minimum distance between stokeslets. We illustrate the
prevalence of this robust chiral motion with experiments on small macroscopic
objects of arbitrary shape.Comment: 35 pages, 10 figures; Section VII.A redone and other edits made for
clarity. Accepted by Phys. Rev.
3D Brownian Diffusion of Submicron-Sized Particle Clusters
We report on the translation and rotation of particle clusters made through
the combination of spherical building blocks. These clusters present ideal
model systems to study the motion of objects with complex shape. Because they
could be separated into fractions of well-defined configurations on a
sufficient scale and their overall dimensions were below 300 nm, the
translational and rotational diffusion coefficients of particle duplets,
triplets and tetrahedrons could be determined by a combination of polarized
dynamic light scattering (DLS) and depolarized dynamic light scattering (DDLS).
The use of colloidal clusters for DDLS experiments overcomes the limitation of
earlier experiments on the diffusion of complex objects near surfaces because
the true 3D diffusion can be studied. When the exact geometry of the complex
assemblies is known, different hydrodynamic models for calculating the
diffusion coefficient for objects with complex shapes could be applied. Because
hydrodynamic friction must be restricted to the cluster surface the so-called
shell model, in which the surface is represented as a shell of small friction
elements, was most suitable to describe the dynamics. A quantitative comparison
of the predictions from theoretical modeling with the results obtained by DDLS
showed an excellent agreement between experiment and theory
Elastohydrodynamic lubrication properties and friction behaviors of several ester base stocks
Trees and Graphs: Simple, General, Abstract, and Efficient
Report published in the Proceedings of the National Conference on "Education and Research in the Information Society", Plovdiv, May, 2019The representations of trees and graphs in general, as known from most textbooks
on data structures and algorithms or similar sources, are in various ways deficient and outdated.
We offer a straightforward approach, based on the notions of set and map, which is at once
abstract, general, and efficient, and thus beneficial to the theory, practice, and teaching of
programming.Association for the Development of the Information Societ
The Role of the Language in Teaching Introductory Programming
Report published in the Proceedings of the National Conference on "Education and Research in the Information Society", Plovdiv, June, 2017Based on a present-day view of teaching programming, desirable features are
formulated for a language suitable for teaching introductory programming. On the examples of
programs solving several very simple problems, a comparative evaluation is done of the
languages Java and Ruby in this respect. The significance of visualization in programming
education is outlined, and a suitable solution for graphical visualization is pointed at.Association for the Development of the Information Society, Institute of Mathematics and Informatics Bulgarian Academy of Sciences, Plovdiv University "Paisii Hilendarski
ΠΠ·ΠΈΠΊ Π·Π° ΠΊΠΎΠΌΠΏΠΎΠ·ΠΈΡΠΈΠΎΠ½Π½ΠΎ ΠΏΡΠΎΠ³ΡΠ°ΠΌΠΈΡΠ°Π½Π΅: ΠΠ±ΠΎΡΠ½ΠΎΠ²ΠΊΠ° ΠΈ ΠΊΠΎΠ½ΡΡΡΡΠΊΡΠΈΡ
ΠΠΎΠΉΠΊΠΎ ΠΠ». ΠΠ°Π½ΡΠ΅Π² - ΠΡΠ΅Π΄ΡΡΠ°Π²Π΅Π½Π° Π΅ ΠΎΠ±ΠΎΡΠ½ΠΎΠ²ΠΊΠ° ΠΈ ΠΎΠΏΠΈΡΠ°Π½ΠΈΠ΅ Π½Π° Π΅Π·ΠΈΠΊ Π·Π° ΠΏΡΠΎΠ³ΡΠ°ΠΌΠΈΡΠ°Π½Π΅ Π² ΠΊΠΎΠΌΠΏΠΎΠ·ΠΈΡΠΈΠΎΠ½Π΅Π½
ΡΡΠΈΠ» Π·Π° ΠΎΠΏΠΈΡΠ½ΠΈ ΠΈ ΡΡΠ΅Π±Π½ΠΈ ΡΠ΅Π»ΠΈ. ΠΠΎΠ΄ βΠΊΠΎΠΌΠΏΠΎΠ·ΠΈΡΠΈΠΎΠ½Π΅Π½β ΠΈΠΌΠ°ΠΌΠ΅ ΠΏΡΠ΅Π΄Π²ΠΈΠ΄ ΡΡΠ½ΠΊΡΠΈΠΎΠ½Π°Π»Π΅Π½ ΡΡΠΈΠ» Π½Π° ΠΏΡΠΎΠ³ΡΠ°ΠΌΠΈΡΠ°Π½Π΅, ΠΏΡΠΈ ΠΊΠΎΠΉΡΠΎ ΠΏΡΠ΅ΡΠΌΡΡΠ°Π½Π΅ΡΠΎ Π΅ ΠΉΠ΅ΡΠ°ΡΡ
ΠΈΡ ΠΎΡ ΠΊΠΎΠΌΠΏΠΎΠ·ΠΈΡΠΈΠΈ ΠΈ ΠΏΡΠΈΠ»Π°Π³Π°Π½ΠΈΡ Π½Π° ΡΡΠ½ΠΊΡΠΈΠΈ. ΠΠ΄ΠΈΠ½ ΠΎΡ Π΄Π°Π½Π½ΠΎΠ²ΠΈΡΠ΅ ΡΠΈΠΏΠΎΠ²Π΅ Π½Π° Π΅Π·ΠΈΠΊΠ° Π΅ ΡΠΎΠ·ΠΈ Π½Π°
Π³Π΅ΠΎΠΌΠ΅ΡΡΠΈΡΠ½ΠΈΡΠ΅ ΡΠΈΠ³ΡΡΠΈ, ΠΊΠΎΠΈΡΠΎ ΠΌΠΎΠ³Π°Ρ Π΄Π° Π±ΡΠ΄Π°Ρ ΠΏΠΎΠ»ΡΡΠ°Π²Π°Π½ΠΈ ΡΡΠ΅Π· ΠΏΡΠΎΡΡΠΈ ΠΏΡΠ°Π²ΠΈΠ»Π°
Π·Π° ΡΡΠΎΡΠ½Π°ΡΡΠ½Π΅ ΠΈ ΡΠ°ΠΊΠ° ΡΡΡΠΎ ΠΎΠ±ΡΠ°Π·ΡΠ²Π°Ρ ΠΉΠ΅ΡΠ°ΡΡ
ΠΈΡΠ½ΠΈ ΠΊΠΎΠΌΠΏΠΎΠ·ΠΈΡΠΈΠΈ. ΠΠ·ΠΈΠΊΡΡ Π΅ ΡΠΈΠ»Π½ΠΎ
ΠΏΠΎΠ²Π»ΠΈΡΠ½ ΠΎΡ GeomLab, Π½ΠΎ ΠΏΠΎ ΡΠ΅Π΄ΠΈΡΠ° ΡΠ²ΠΎΠΉΡΡΠ²Π° ΡΠ΅ ΡΠ°Π·Π»ΠΈΡΠ°Π²Π° ΠΎΡ Π½Π΅Π³ΠΎ Π·Π½Π°ΡΠΈΡΠ΅Π»Π½ΠΎ. Π‘ΡΠ°ΡΠΈΡΡΠ° ΡΠ°Π·Π³Π»Π΅ΠΆΠ΄Π° ΠΎΡΠ½ΠΎΠ²Π½ΠΈΡΠ΅ ΡΠ΅ΡΡΠΈ Π½Π° Π΅Π·ΠΈΠΊΠ°; ΠΏΠΎΠ΄ΡΠΎΠ±Π½ΠΎΡΠΎ ΠΌΡ ΠΎΠΏΠΈΡΠ°Π½ΠΈΠ΅ ΠΈ
ΡΠΈΠ³ΡΡΠ½ΠΎΠΊΠΎΠ½ΡΡΡΡΠΊΡΠΈΠ²Π½ΠΈΡΠ΅ ΠΌΡ Π²ΡΠ·ΠΌΠΎΠΆΠ½ΠΎΡΡΠΈ ΡΠ΅ Π±ΡΠ΄Π°Ρ ΠΏΡΠ΅Π΄ΡΡΠ°Π²Π΅Π½ΠΈ Π² ΡΡΠΏΡΡΡΡΠ²Π°ΡΠ°
ΠΏΡΠ±Π»ΠΈΠΊΠ°ΡΠΈΡ.A rationale and description of a language for exploratory and educational programming in a compositional style is presented. By βcompositionalβ a functional programming style is meant where the computation is a hierarchy of function compositions
and applications. One of the datatypes of the language is that of the geometrical
figures that can be obtained by simple rules of spatial correlation, thus, too, forming
hierarchical compositions. The language is strongly influenced by GeomLab, but
differs from it substantially in many respects. The paper discusses the main features
of the language; the detailed description along with the picture construction facilities
will be presented in an accompanying publication. *2000 Mathematics Subject Classification: 68N15, 68N18
Programming as Metacalculation
Report published in the Proceedings of the National Conference on "Education in the Information Society", Plovdiv, May, 2013Elements of an approach to teaching programming in school are described, based on the
functional paradigm and harmonically blending programming, calculation, and algebra. We
believe that it ensures a smooth introduction to programming, free of contrived concepts and
constructs, and also fosters the teaching of a wider and deeper mathematics in school.Association for the Development of the Information Society, Institute of Mathematics and Informatics Bulgarian Academy of Science
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