229 research outputs found

    Energy Meter for Charging Stand in Smart Buildings

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    This paper describes the design of smart energy meter and its = implementation, focusing on its firmware, which is based on real time operating system FreeRTOS. The main areas to use this energy meter are charging stations (stands) for electric vehicle (follows as EV) charging support and possible embedding into current smart building technology. This paper also presents the results of a research of commercial devices available in Czech Republic for energy measuring for buildings as well as the analysis of energy meter for specific purposes. For example, the description of the module includes the required measurement of voltage, electric current and frequency of power network. After integration into smart buildings (home automation, parking houses). there are pros and cons of such solutions mentioned

    Size-resolved aerosol water-soluble ionic compositions in the summer of Beijing: implication of regional secondary formation

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    To characterize aerosol pollution in Beijing, size-resolved aerosols were collected by MOUDIs during CAREBEIJING-2006 field campaign at Peking University (urban site) and Yufa (upwind rural site). Fine particle concentrations (PM<sub>1.8</sub> by MOUDI) were 99.8±77.4 μg/m<sup>3</sup> and 78.2±58.4 μg/m<sup>3</sup>, with PM<sub>1.8</sub>/PM<sub>10</sub> ratios of 0.64±0.08 and 0.76±0.08 at PKU and Yufa, respectively, and secondary compounds accounted for more than 50% in fine particles. PMF model analysis was used to resolve the particle modes. Three modes were resolved at Yufa, representing condensation, droplet and coarse mode. However, one more droplet mode with bigger size was resolved, which was considered probably from regional transport. Condensation mode accounted for 10%–60% of the total mass at both sites, indicating that the gas-to-particle condensation process was important in summer. The formation of sulfate was mainly attributed to in-cloud or aerosol droplet process (PKU 80%, Yufa 70%) and gas condensation process (PKU 14%, Yufa 22%). According to the thermodynamic instability of NH<sub>4</sub>NO<sub>3</sub>, size distributions of nitrate were classified as three categories by RH. The existence of Ca(NO<sub>3</sub>)<sub>2</sub> in droplet mode indicated the reaction of HNO<sub>3</sub> with crustal particles was also important in fine particles. A rough estimation was given that 69% of the PM<sub>10</sub> and 87% of the PM<sub>1.8</sub> in Beijing urban were regional contributions. Sulfate, ammonium and oxalate were formed regionally, with the regional contributions of 90%, 87% and 95% to PM<sub>1.8</sub>. Nitrate formation was local dominant. In summary regional secondary formation led to aerosol pollution in the summer of Beijing

    Collective Behavior of Asperities in Dry Friction at Small Velocities

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    We investigate a simple model of dry friction based on extremal dynamics of asperities. At small velocities, correlations develop between the asperities, whose range becomes infinite in the limit of infinitely slow driving, where the system is self-organized critical. This collective phenomenon leads to effective aging of the asperities and results in velocity dependence of the friction force in the form F1exp(1/v)F\sim 1- \exp(-1/v).Comment: 7 pages, 8 figures, revtex, submitted to Phys. Rev.

    Vacancy decay in endohedral atoms: the role of non-central position of the atom

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    We demonstrate that the Auger decay rate in an endohedral atom is very sensitive to the atom's location in the fullerene cage. Two additional decay channels appear in an endohedral system: (a) the channel due to the change in the electric field at the atom caused by dynamic polarization of the fullerene electron shell by the Coulomb field of the vacancy, (b) the channel within which the released energy is transferred to the fullerene electron via the Coulomb interaction. % The relative magnitudes of the correction terms are dependent not only on the position of the doped atom but also on the transition energy \om. Additional enhancement of the decay rate appears for transitions whose energies are in the vicinity of the fullerene surface plasmons energies of high multipolarity. % It is demonstrated that in many cases the additional channels can dominate over the direct Auger decay resulting in pronounced broadening of the atomic emission lines. % The case study, carried out for Sc2+^{2+}@C806_{80}^{6-}, shows that narrow autoionizing resonances in an isolated Sc2+^{2+} within the range \om = 30... 45 eV are dramatically broadened if the ion is located strongly off-the-center. % Using the developed model we carry out quantitative analysis of the photoionization spectrum for the endohedral complex Sc3_3N@C80_{80} and demonstrate that the additional channels are partly responsible for the strong modification of the photoionization spectrum profile detected experimentally by M\"{u}ller et al. (J. Phys.: Conf. Ser. 88, 012038 (2008)).Comment: 32 pages, 11 figure

    Cracking Piles of Brittle Grains

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    A model which accounts for cracking avalanches in piles of grains subject to external load is introduced and numerically simulated. The stress is stochastically transferred from higher layers to lower ones. Cracked areas exhibit various morphologies, depending on the degree of randomness in the packing and on the ductility of the grains. The external force necessary to continue the cracking process is constant in wide range of values of the fraction of already cracked grains. If the grains are very brittle, the force fluctuations become periodic in early stages of cracking. Distribution of cracking avalanches obeys a power law with exponent τ=2.4±0.1\tau = 2.4 \pm 0.1.Comment: RevTeX, 6 pages, 7 postscript figures, submitted to Phys. Rev.

    Inelastically scattering particles and wealth distribution in an open economy

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    Using the analogy with inelastic granular gasses we introduce a model for wealth exchange in society. The dynamics is governed by a kinetic equation, which allows for self-similar solutions. The scaling function has a power-law tail, the exponent being given by a transcendental equation. In the limit of continuous trading, closed form of the wealth distribution is calculated analytically.Comment: 8 pages 5 figure

    Nucleation of a sodium droplet on C60

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    We investigate theoretically the progressive coating of C60 by several sodium atoms. Density functional calculations using a nonlocal functional are performed for NaC60 and Na2C60 in various configurations. These data are used to construct an empirical atomistic model in order to treat larger sizes in a statistical and dynamical context. Fluctuating charges are incorporated to account for charge transfer between sodium and carbon atoms. By performing systematic global optimization in the size range 1<=n<=30, we find that Na_nC60 is homogeneously coated at small sizes, and that a growing droplet is formed above n=>8. The separate effects of single ionization and thermalization are also considered, as well as the changes due to a strong external electric field. The present results are discussed in the light of various experimental data.Comment: 17 pages, 10 figure

    Basic kinetic wealth-exchange models: common features and open problems

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    We review the basic kinetic wealth-exchange models of Angle [J. Angle, Social Forces 65 (1986) 293; J. Math. Sociol. 26 (2002) 217], Bennati [E. Bennati, Rivista Internazionale di Scienze Economiche e Commerciali 35 (1988) 735], Chakraborti and Chakrabarti [A. Chakraborti, B. K. Chakrabarti, Eur. Phys. J. B 17 (2000) 167], and of Dragulescu and Yakovenko [A. Dragulescu, V. M. Yakovenko, Eur. Phys. J. B 17 (2000) 723]. Analytical fitting forms for the equilibrium wealth distributions are proposed. The influence of heterogeneity is investigated, the appearance of the fat tail in the wealth distribution and the relaxation to equilibrium are discussed. A unified reformulation of the models considered is suggested.Comment: Updated version; 9 pages, 5 figures, 2 table

    Modeling Molecular Interactions in Water: From Pairwise to Many-Body Potential Energy Functions.

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    Almost 50 years have passed from the first computer simulations of water, and a large number of molecular models have been proposed since then to elucidate the unique behavior of water across different phases. In this article, we review the recent progress in the development of analytical potential energy functions that aim at correctly representing many-body effects. Starting from the many-body expansion of the interaction energy, specific focus is on different classes of potential energy functions built upon a hierarchy of approximations and on their ability to accurately reproduce reference data obtained from state-of-the-art electronic structure calculations and experimental measurements. We show that most recent potential energy functions, which include explicit short-range representations of two-body and three-body effects along with a physically correct description of many-body effects at all distances, predict the properties of water from the gas to the condensed phase with unprecedented accuracy, thus opening the door to the long-sought "universal model" capable of describing the behavior of water under different conditions and in different environments
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