1,766 research outputs found
KINETIC FEATURES OF THE DISSOCIATION PROCESS OF GAS HYDRATE DEPOSITS
The research is aimed at revealing the theoretical features of the kinetics of the process of
dissociation of natural gas hydrates, the accounting of which is useful in designing technologies for
their development. The process of decomposition of gas hydrates is considered as a heterogeneous
process, proceeding at the interface of the phases and contains three consecutive stages. The
mathematically grounded speed with which molecules fluctuate around fixed positions and the velocity
of their translational motion in the system āgas ā rock environmentā. The mathematical expression of
the constant coefficient of molecular diffusion is made. It has been established that when gas is
extracted from gas hydrates, external and internal diffusion zones, as well as diffusion inhibition, are
caused, which causes an increase in the decay time of gas hydrate to gas and water. The character of
the dependence of the change in the rate of dissociation during its various periods is revealed. It was
found that the speed of the dissociation process in these conditions varies with the temperature under
the exponential la
Optimizing Associative Information Transfer within Content-addressable Memory
Original article can be found at: http://www.oldcitypublishing.com/IJUC/IJUC.htmlPeer reviewe
Numerical simulation of spacecraft charging phenomena
A numerical simulation program is being constructed having the following features: (1) infinite circular cylindrical geometry with angle-dependence, (2) inclusion of incident particles, photoelectrons, secondary electrons, backscattered electrons, any gun emissions, and any internal current pathways including surface conductive layers, (3) quasistatic time-dependent iteration, in which sheath potential changes during particle transit times are ignored, (4) use of approximate, locally-dependent space charge density expressions in solving Poisson's equation for sheath potentials, with use of numerical orbit-following to determine surface currents, and (5) incident particle velocity distributions isotropic or beam-like, or some superposition of these. Rationales for each of these features are discussed
Prediction of large negative shaded-side spacecraft potentials
A calculation by Knott, for the floating potential of a spherically symmetric synchronous-altitude satellite in eclipse, was adapted to provide simple calculations of upper bounds on negative potentials which may be achieved by electrically isolated shaded surfaces on spacecraft in sunlight. Large (approximately 60 percent) increases in predicted negative shaded-side potentials are obtained. To investigate effective potential barrier or angular momentum selection effects due to the presence of less negative sunlit-side or adjacent surface potentials, these expressions were replaced by the ion random current, which is a lower bound for convex surfaces when such effects become very severe. Further large increases in predicted negative potentials were obtained, amounting to a doubling in some cases
Percolation Centrality: Quantifying Graph-Theoretic Impact of Nodes during Percolation in Networks
A number of centrality measures are available to determine the relative importance of a node in a complex network, and betweenness is prominent among them. However, the existing centrality measures are not adequate in network percolation scenarios (such as during infection transmission in a social network of individuals, spreading of computer viruses on computer networks, or transmission of disease over a network of towns) because they do not account for the changing percolation states of individual nodes. We propose a new measure, percolation centrality, that quantifies relative impact of nodes based on their topological connectivity, as well as their percolation states. The measure can be extended to include random walk based definitions, and its computational complexity is shown to be of the same order as that of betweenness centrality. We demonstrate the usage of percolation centrality by applying it to a canonical network as well as simulated and real world scale-free and random networks. Ā© 2013 Piraveenan et al.published_or_final_versio
Gliders2d: Source Code Base for RoboCup 2D Soccer Simulation League
We describe Gliders2d, a base code release for Gliders, a soccer simulation
team which won the RoboCup Soccer 2D Simulation League in 2016. We trace six
evolutionary steps, each of which is encapsulated in a sequential change of the
released code, from v1.1 to v1.6, starting from agent2d-3.1.1 (set as the
baseline v1.0). These changes improve performance by adjusting the agents'
stamina management, their pressing behaviour and the action-selection
mechanism, as well as their positional choice in both attack and defense, and
enabling riskier passes. The resultant behaviour, which is sufficiently generic
to be applicable to physical robot teams, increases the players' mobility and
achieves a better control of the field. The last presented version,
Gliders2d-v1.6, approaches the strength of Gliders2013, and outperforms
agent2d-3.1.1 by four goals per game on average. The sequential improvements
demonstrate how the methodology of human-based evolutionary computation can
markedly boost the overall performance with even a small number of controlled
steps.Comment: 12 pages, 1 figure, Gliders2d code releas
Minimising the kullback-leibler divergence for model selection in distributed nonlinear systems
Ā© 2018 by the authors. The Kullback-Leibler (KL) divergence is a fundamental measure of information geometry that is used in a variety of contexts in artificial intelligence. We show that, when system dynamics are given by distributed nonlinear systems, this measure can be decomposed as a function of two information-theoretic measures, transfer entropy and stochastic interaction. More specifically, these measures are applicable when selecting a candidate model for a distributed system, where individual subsystems are coupled via latent variables and observed through a filter. We represent this model as a directed acyclic graph (DAG) that characterises the unidirectional coupling between subsystems. Standard approaches to structure learning are not applicable in this framework due to the hidden variables; however, we can exploit the properties of certain dynamical systems to formulate exact methods based on differential topology. We approach the problem by using reconstruction theorems to derive an analytical expression for the KL divergence of a candidate DAG from the observed dataset. Using this result, we present a scoring function based on transfer entropy to be used as a subroutine in a structure learning algorithm. We then demonstrate its use in recovering the structure of coupled Lorenz and Rƶssler systems
Local information transfer as a spatiotemporal filter for complex systems
We present a measure of local information transfer, derived from an existing
averaged information-theoretical measure, namely transfer entropy. Local
transfer entropy is used to produce profiles of the information transfer into
each spatiotemporal point in a complex system. These spatiotemporal profiles
are useful not only as an analytical tool, but also allow explicit
investigation of different parameter settings and forms of the transfer entropy
metric itself. As an example, local transfer entropy is applied to cellular
automata, where it is demonstrated to be a novel method of filtering for
coherent structure. More importantly, local transfer entropy provides the first
quantitative evidence for the long-held conjecture that the emergent traveling
coherent structures known as particles (both gliders and domain walls, which
have analogues in many physical processes) are the dominant information
transfer agents in cellular automata.Comment: 12 page
Numerical Modelling of Whispering Gallery Modes in Parallel-plates Type Cylindrical Anisotropic Dielectric Resonators
A parallel-plates-type cylindrical anisotropic dielectric resonator (DR) with whispering gallery modes (WGMs) has been investigated. Numerical modelling of the resonance frequencies, Q-factors and the electric field filling factors of the isotropic and anisotropic DR are presented. Applications of the results for sensing purposes are discussed
Whispering Gallery Mode Dielectric Resonators for the Millimeter Wave Near Field Sensing Applications
The resonance characteristics of whispering gallery modes (WGMs) in parallel-plate type cylindrical dielectric resonators (DRs) are numerically considered to optimise their characteristics for sensing applications. Results for the dependency of the resonant frequency, Q-factor, slow-down factor and electric energy filling factor of the modes on resonator parameters for both isotropic and anisotropic DR are presented. The possible applications of the results for millimeter wave near field nondestructive measurements are discussed
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