236 research outputs found
On the Use of Matrix Factorization Techniques in Penalty Function Methods for Structured Linear Programs
An algorithm converging to an optimal solution of a linear program in a finite number of steps is proposed. The algorithm is based on the use of smooth penalty functions as well as on matrix factorization techniques. It consists of finding corner points of the piece-wise linear unconstrained minima trajectory.
The application of the algorithm to dynamic linear programs and block-angular programs is described
Do logarithmic proximity measures outperform plain ones in graph clustering?
We consider a number of graph kernels and proximity measures including
commute time kernel, regularized Laplacian kernel, heat kernel, exponential
diffusion kernel (also called "communicability"), etc., and the corresponding
distances as applied to clustering nodes in random graphs and several
well-known datasets. The model of generating random graphs involves edge
probabilities for the pairs of nodes that belong to the same class or different
predefined classes of nodes. It turns out that in most cases, logarithmic
measures (i.e., measures resulting after taking logarithm of the proximities)
perform better while distinguishing underlying classes than the "plain"
measures. A comparison in terms of reject curves of inter-class and intra-class
distances confirms this conclusion. A similar conclusion can be made for
several well-known datasets. A possible origin of this effect is that most
kernels have a multiplicative nature, while the nature of distances used in
cluster algorithms is an additive one (cf. the triangle inequality). The
logarithmic transformation is a tool to transform the first nature to the
second one. Moreover, some distances corresponding to the logarithmic measures
possess a meaningful cutpoint additivity property. In our experiments, the
leader is usually the logarithmic Communicability measure. However, we indicate
some more complicated cases in which other measures, typically, Communicability
and plain Walk, can be the winners.Comment: 11 pages, 5 tables, 9 figures. Accepted for publication in the
Proceedings of 6th International Conference on Network Analysis, May 26-28,
2016, Nizhny Novgorod, Russi
-Matrix of Nonlocal Scalar Quantum Field Theory in the Representation of Basis Functions
Nonlocal quantum theory of one-component scalar field in -dimensional
Euclidean spacetime is studied in representations of -matrix
theory for both polynomial and nonpolynomial interaction Lagrangians. The
theory is formulated on coupling constant in the form of an infrared smooth
function of argument for space without boundary. Nonlocality is given by
evolution of Gaussian propagator for the local free theory with ultraviolet
form factors depending on ultraviolet length parameter . By representation
of the -matrix in terms of abstract functional integral over
primary scalar field, the form of a grand canonical partition
function is found. And, by expression of -matrix in terms of the
partition function, the representation for in terms of basis
functions is obtained. Derivations are given for discrete case where basis
functions are Hermite functions, and for continuous case where basis functions
are trigonometric functions. The obtained expressions for the
-matrix are investigated within the framework of variational
principle based on Jensen inequality. Equations with separable kernels
satisfied by variational function are found and solved, yielding results
for both the polynomial theory and the nonpolynomial sine-Gordon
theory. A new definition of the -matrix is proposed to solve
additional divergences which arise in application of Jensen inequality for the
continuous case. Analytical results are illustrated numerically. For simplicity
of numerical calculation: the case is considered, and propagator for the
free theory is in the form of Gaussian function typically in the
Virton-Quark model. The formulation for nonlocal QFT in momentum space of
extra dimensions with subsequent compactification into physical spacetime is
discussed.Comment: 38 pages, 18 figures; v2: significant text editing; v3: text and
plots edited, references and acknowledgments added; prepared for the special
issue of the journal Particles in memory of G.V. Efimo
Analysis of Collectivism and Egoism Phenomena within the Context of Social Welfare
Comparative benefits provided by the basic social strategies including
collectivism and egoism are investigated within the framework of democratic
decision-making. In particular, we study the mechanism of growing "snowball" of
cooperation.Comment: 12 pages, 5 figures. Translated from Russian. Original Russian Text
published in Problemy Upravleniya, 2008, No. 4, pp. 30-3
Production environment and employees` labour activity factors of auxiliary departments of JSC «Naftan»
Communication Society and Security: Current Threats and Legal Maintenance
Over many centuries, human societies across the globe have established progressively closer contacts. Recently, the pace of globalization has dramatically increased. Unprecedented changes in communications, transportation, and computer technology have given the process new impetus and made the world more interdependent than ever. Information resources and structures have become a tool for achieving a strategic advantage. The authenticity, credibility, and an adequate reflection of information realities represent the key challenges for the communication society. Our research aims to analyze the possibilities of establishing a profound system for countering legalization of proceeds from crime (money laundering) and creating efficient barriers against cybercrimes, such as hacking of personal data. The sphere of security of online communication processes has become an objective element of our life, and it couldn’t be ignored, especially due to further development of securing biometric personal data mechanisms
Morphology and Optical Investigations of InAs-QD/GaAs Heterostructures Obtained by Ion-Beam Sputtering
Planetary Trojans - the main source of short period comets?
We present a short review of the impact regime experienced by the terrestrial
planets within our own Solar system, describing the three populations of
potentially hazardous objects which move on orbits that take them through the
inner Solar system. Of these populations, the origins of two (the Near-Earth
Asteroids and the Long-Period Comets) are well understood, with members
originating in the Asteroid belt and Oort cloud, respectively. By contrast, the
source of the third population, the Short-Period Comets, is still under debate.
The proximate source of these objects is the Centaurs, a population of
dynamically unstable objects that pass perihelion between the orbits of Jupiter
and Neptune. However, a variety of different origins have been suggested for
the Centaur population. Here, we present evidence that at least a significant
fraction of the Centaur population can be sourced from the planetary Trojan
clouds, stable reservoirs of objects moving in 1:1 mean-motion resonance with
the giant planets (primarily Jupiter and Neptune). Focusing on simulations of
the Neptunian Trojan population, we show that an ongoing flux of objects should
be leaving that region to move on orbits within the Centaur population. With
conservative estimates of the flux from the Neptunian Trojan clouds, we show
that their contribution to that population could be of order ~3%, while more
realistic estimates suggest that the Neptune Trojans could even be the main
source of fresh Centaurs. We suggest that further observational work is needed
to constrain the contribution made by the Neptune Trojans to the ongoing flux
of material to the inner Solar system, and believe that future studies of the
habitability of exoplanetary systems should take care not to neglect the
contribution of resonant objects (such as planetary Trojans) to the impact flux
that could be experienced by potentially habitable worlds.Comment: 16 pages, 4 figures, published in the International Journal of
Astrobiology (the arXiv.org's abstract was shortened, but the original one
can be found in the manuscript file
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