2,346 research outputs found
Application of Supercomputer Technologies for Simulation of Socio-Economic Systems
To date, an extensive experience has been accumulated in investigation of problems related to quality, assessment of management systems, modeling of economic system sustainability. The studies performed have created a basis for formation of a new research area — Economics of Quality. Its tools allow to use opportunities of model simulation for construction of the mathematical models adequately reflecting the role of quality in natural, technical, social regularities of functioning of the complex socioeconomic systems. Extensive application and development of models, and also system modeling with use of supercomputer technologies, on our deep belief, will bring the conducted researches of social and economic systems to essentially new level. Moreover, the current scientific research makes a significant contribution to model simulation of multi-agent social systems and that isn’t less important, it belongs to the priority areas in development of science and technology in our country. This article is devoted to the questions of supercomputer technologies application in public sciences, first of all, — regarding technical realization of the large-scale agent-focused models (AFM). The essence of this tool is that owing to increase in power of computers it became possible to describe the behavior of many separate fragments of a difficult system, as social and economic systems represent. The article also deals with the experience of foreign scientists and practicians in launching the AFM on supercomputers, and also the example of AFM developed in CEMI RAS, stages and methods of effective calculating kernel display of multi-agent system on architecture of a modern supercomputer will be analyzed. The experiments on the basis of model simulation on forecasting the population of St. Petersburg according to three scenarios as one of the major factors influencing the development of social and economic system and quality of life of the population are presented in the conclusion
Nanoscopy of pairs of atoms by fluorescence in a magnetic field
Spontaneous emission spectra of two initially excited closely spaced
identical atoms are very sensitive to the strength and the direction of the
applied magnetic field. The relevant schemes are considered that ensure the
determination of the mutual spatial orientation of the atoms and the distance
between them by entirely optical means. A corresponding theoretical description
is given accounting for the dipole-dipole interaction between the two atoms in
the presence of a magnetic field and for polarizations of the quantum field
interacting with magnetic sublevels of the two-atom system
Hacking commercial quantum cryptography systems by tailored bright illumination
The peculiar properties of quantum mechanics allow two remote parties to
communicate a private, secret key, which is protected from eavesdropping by the
laws of physics. So-called quantum key distribution (QKD) implementations
always rely on detectors to measure the relevant quantum property of single
photons. Here we demonstrate experimentally that the detectors in two
commercially available QKD systems can be fully remote-controlled using
specially tailored bright illumination. This makes it possible to tracelessly
acquire the full secret key; we propose an eavesdropping apparatus built of
off-the-shelf components. The loophole is likely to be present in most QKD
systems using avalanche photodiodes to detect single photons. We believe that
our findings are crucial for strengthening the security of practical QKD, by
identifying and patching technological deficiencies.Comment: Revised version, rewritten for clarity. 5 pages, 5 figures. To
download the Supplementary information (which is in open access), go to the
journal web site at http://dx.doi.org/10.1038/nphoton.2010.21
Signum Function Method for Generation of Correlated Dichotomic Chains
We analyze the signum-generation method for creating random dichotomic
sequences with prescribed correlation properties. The method is based on a
binary mapping of the convolution of continuous random numbers with some
function originated from the Fourier transform of a binary correlator. The goal
of our study is to reveal conditions under which one can construct binary
sequences with a given pair correlator. Our results can be used in the
construction of superlattices and waveguides with selective transport
properties.Comment: 14 pages, 7 figure
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