673 research outputs found

    Rate of convergence and Edgeworth-type expansion in the entropic central limit theorem

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    An Edgeworth-type expansion is established for the entropy distance to the class of normal distributions of sums of i.i.d. random variables or vectors, satisfying minimal moment conditions.Comment: Published in at http://dx.doi.org/10.1214/12-AOP780 the Annals of Probability (http://www.imstat.org/aop/) by the Institute of Mathematical Statistics (http://www.imstat.org

    Electrochemical synthesis of hydrogen with depolarization of the anodic process

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    A new active composite coating for graphite gas diffusion electrode for hybrid sulfur cycle was proposed. The kinetics of oxidation of SO₂ were studied on porous graphite anodes with different catalytic coatings. It was shown that the most efficient composite coating is based on activated carbon and platinum supported on graphite gas diffusion substrate. The voltage drop in the laboratory electrochemical cell was 1.3 V at a current density of 1000 A·m⁻². This corresponds to a specific consumption of 3.1 kWh electric energy per 1 m³ of hydrogen

    Plasma Equilibrium inside Various Cross-Section Capillary Discharges

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    Plasma properties inside a hydrogen-filled capillary discharge waveguide were modeled with dissipative magnetohydrodynamic simulations to enable analysis of capillaries of circular and square cross-sections implying that square capillaries can be used to guide circularly-symmetric laser beams. When the quasistationary stage of the discharge is reached, the plasma and temperature in the vicinity of the capillary axis has almost the same profile for both the circular and square capillaries. The effect of cross-section on the electron beam focusing properties were studied using the simulation-derived magnetic field map. Particle tracking simulations showed only slight effects on the electron beam symmetry in the horizontal and diagonal directions for square capillary.Comment: 6 pages, 10 figure

    On the reconstruction of planar lattice-convex sets from the covariogram

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    A finite subset KK of Zd\mathbb{Z}^d is said to be lattice-convex if KK is the intersection of Zd\mathbb{Z}^d with a convex set. The covariogram gKg_K of KZdK\subseteq \mathbb{Z}^d is the function associating to each u \in \integer^d the cardinality of K(K+u)K\cap (K+u). Daurat, G\'erard, and Nivat and independently Gardner, Gronchi, and Zong raised the problem on the reconstruction of lattice-convex sets KK from gKg_K. We provide a partial positive answer to this problem by showing that for d=2d=2 and under mild extra assumptions, gKg_K determines KK up to translations and reflections. As a complement to the theorem on reconstruction we also extend the known counterexamples (i.e., planar lattice-convex sets which are not reconstructible, up to translations and reflections) to an infinite family of counterexamples.Comment: accepted in Discrete and Computational Geometr

    Water-repellent coatings for surface and 3D wood processing

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    The paper presents the results of research in organic chemical compositions for hydrophobic protection of wood with the use of surface and three-dimensional coating techniques of impregnation and chemical compositions. Water absorption indicators, angles of contact on the surface of treated samples are detected herein. Kinetic equation of the moisture diffusion transition in capillary-porous structure of wood is suggested

    Hydrophobic composition based on mixed-molecular weight polyethylene

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    The paper presents investigations of compositions based on low and high molecular weight polyethylene so as to synthesize a hydrophobic composition for moisture protection of timber. X-ray phase analysis and measurements of the tear-off force of hydrophobic coating needed to apply to the timber surface and the limiting wetting angle are carried out to detect the hydrophobic, adhesive, electrophysical, and physicochemical properties of compositions. Kinetic dependencies are given for moisture absorption of timber specimens. It is shown that the preliminary formation of the texture by the surface patterning or its treatment with low-temperature plasma with the following protective coating results in the improvement of hydrophobic properties of the suggested compositions. These compositions can be used in the capacity of water repellents to protect building materials from moisture including restoration works

    Russia’s Birth Rate Dynamics Forecasting

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    This article covers contemporary issues of Russia’s population reproduction, their causes and the state policy aimed to overcome the same. The urgency to fulfill the task related to assessment of the most probable future dynamics of Russia’s population birth rate in the context of a low child-woman ratio, and subject to an impact of pronatalist policies implemented by the state, is justified. In order to fulfill the task based on the crude birth rate behavior probability distribution function, a probabilistic assessment of future dynamics of Russia’s population reproduction has been carried out. Based on a modernized method suggested by Hurst, the following two forecasting paths of the crude birth rate dynamics have been built: the first path conforms to the scenario where a value of the crude birth rate is to tend to values between 8–10.5 births/1,000 people (probability is 0.182), in particular, through a negative external impact, the second path is to tend to values between 13–16.5 births/1,000 people (probability — 0.618), in particular, through a positive external impact. Notwithstanding that these scenarios significantly differ from each other, the paths of the crude birth rate dynamics for 2015–2041, corresponding to the reliable prediction time, forecasted according to the abovementioned scenarios, are virtually identical. The analysis of the findings allowed for the conclusion that the state demographic policy is not capable of having a significant impact on the future dynamics of the birth rate, substantially determined by the current situation and conjuncture shifts. These conclusions confirm the view prevailing in academic circles and suggesting that the state regulation of Russia’s demographic situation should be primarily focused on the improvement in health and a rise in the life expectancy of the population

    Penilaian Kinerja Keuangan Koperasi di Kabupaten Pelalawan

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    This paper describe development and financial performance of cooperative in District Pelalawan among 2007 - 2008. Studies on primary and secondary cooperative in 12 sub-districts. Method in this stady use performance measuring of productivity, efficiency, growth, liquidity, and solvability of cooperative. Productivity of cooperative in Pelalawan was highly but efficiency still low. Profit and income were highly, even liquidity of cooperative very high, and solvability was good

    Impacts of the Tropical Pacific/Indian Oceans on the Seasonal Cycle of the West African Monsoon

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    The current consensus is that drought has developed in the Sahel during the second half of the twentieth century as a result of remote effects of oceanic anomalies amplified by local land–atmosphere interactions. This paper focuses on the impacts of oceanic anomalies upon West African climate and specifically aims to identify those from SST anomalies in the Pacific/Indian Oceans during spring and summer seasons, when they were significant. Idealized sensitivity experiments are performed with four atmospheric general circulation models (AGCMs). The prescribed SST patterns used in the AGCMs are based on the leading mode of covariability between SST anomalies over the Pacific/Indian Oceans and summer rainfall over West Africa. The results show that such oceanic anomalies in the Pacific/Indian Ocean lead to a northward shift of an anomalous dry belt from the Gulf of Guinea to the Sahel as the season advances. In the Sahel, the magnitude of rainfall anomalies is comparable to that obtained by other authors using SST anomalies confined to the proximity of the Atlantic Ocean. The mechanism connecting the Pacific/Indian SST anomalies with West African rainfall has a strong seasonal cycle. In spring (May and June), anomalous subsidence develops over both the Maritime Continent and the equatorial Atlantic in response to the enhanced equatorial heating. Precipitation increases over continental West Africa in association with stronger zonal convergence of moisture. In addition, precipitation decreases over the Gulf of Guinea. During the monsoon peak (July and August), the SST anomalies move westward over the equatorial Pacific and the two regions where subsidence occurred earlier in the seasons merge over West Africa. The monsoon weakens and rainfall decreases over the Sahel, especially in August.Peer reviewe
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