431 research outputs found

    Weighted Differentiation Composition Operator from Logarithmic Bloch Spaces to Zygmund-Type Spaces

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    Let H() denote the space of all holomorphic functions on the unit disk of ℂ, u∈H() and let  n be a positive integer, φ a holomorphic self-map of , and μ a weight. In this paper, we investigate the boundedness and compactness of a weighted differentiation composition operator φ,unf(z)=u(z)f(n)(φ(z)),f∈H(), from the logarithmic Bloch spaces to the Zygmund-type spaces

    Dynamic evolution mechanism of water-bearing coal permeability and water film under stress

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    To explore coal permeability evolution mechanism under the comprehensive action of multiple factors including stress - adsorption - water and slippage effect, considering the coal deformation induced by stress - adsorption, the expression of water film thickness was corrected to quantitatively characterize the effective pore size, and based on this, the intensity of gas slippage effect of water-bearing coal was further quantified and the permeability model was established under the comprehensive action of multiple factors. Combined with experimental research to verify the reliability of permeability model, and then the evolution mechanism of coal permeability, water film and slippage factors under the comprehensive action of multiple factors was further revealed. The results show that under different water saturation conditions, the permeability decreases sharply first and then tends to flat with the increase of effective stress; under the same effective stress condition, the permeability decreases with the increase of water saturation. The water film thickness changes dynamically under the action of stress - adsorption – water, the water film thickness has a negative correlation with stress and adsorption, but a positive correlation with water saturation; the slippage factor increases gradually with the increase of water saturation, but the increase trend is gentle under low stress condition, and more sharply under high stress condition. In addition, based on the disjoining pressure of gas-liquid-solid surface, the expressions of dynamic water film in square and equilateral triangle under the effect of stress-adsorption were deduced, and the evolution mechanisms of gas permeability, water film and slip coefficient of pores with different geometric shapes are compared and analyzed. Due to the presence of corner holes, the order of water film thickness in pores of different geometric forms is circle > square > equilateral triangle from large to small, the order of permeability is opposite; the slippage factor in circular is larger than that in angular pore, while the slippage factor in square and equilateral triangle pore has little difference

    County-level CO2 emissions and sequestration in China during 1997–2017

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    With the implementation of China’s top-down CO2 emissions reduction strategy, the regional differences should be considered. As the most basic governmental unit in China, counties could better capture the regional heterogeneity than provinces and prefecture-level city, and county-level CO2 emissions could be used for the development of strategic policies tailored to local conditions. However, most of the previous accounts of CO2 emissions in China have only focused on the national, provincial, or city levels, owing to limited methods and smaller-scale data. In this study, a particle swarm optimization-back propagation (PSO-BP) algorithm was employed to unify the scale of DMSP/OLS and NPP/VIIRS satellite imagery and estimate the CO2 emissions in 2,735 Chinese counties during 1997–2017. Moreover, as vegetation has a significant ability to sequester and reduce CO2 emissions, we calculated the county-level carbon sequestration value of terrestrial vegetation. The results presented here can contribute to existing data gaps and enable the development of strategies to reduce CO2 emissions in China

    Amplitude analysis of Ds+→π+π−π+D_s^{+} \rightarrow \pi^{+} \pi^{-} \pi^{+}

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    Utilizing the data set corresponding to an integrated luminosity of 3.193.19 fb−1^{-1} collected by the BESIII detector at a center-of-mass energy of 4.178 GeV, we perform an amplitude analysis of the Ds+→π+π−π+D_s^+\to\pi^+\pi^-\pi^+ decay. The sample contains 13,797 candidates with a signal purity of ∼\sim80%. The amplitude and phase of the contributing ππ\pi\pi S{\cal S} wave are measured based on a quasi-model-independent approach, along with the amplitudes and phases of the P{\cal P} and D{\cal D} waves parametrized by Breit-Wigner models. The fit fractions of different intermediate decay channels are also reported.Comment: 14 pages, 6 figure

    Search for New Hadronic Decays of hch_c and Observation of hc→K+K−π+π−π0h_c\rightarrow K^{+}K^{-}\pi^{+}\pi^{-}\pi^{0}

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    Ten hadronic final states of the hch_c decays are investigated via the process ψ(3686)→π0hc\psi(3686)\rightarrow \pi^0 h_c, using a data sample of (448.1±2.9)×106(448.1 \pm 2.9) \times 10^6 ψ(3686)\psi(3686) events collected with the BESIII detector. The decay channel hc→K+K−π+π−π0h_c\rightarrow K^{+}K^{-}\pi^{+}\pi^{-}\pi^{0} is observed for the first time with a significance of 6.0σ6.0 \sigma. The corresponding branching fraction is determined to be B(hc→K+K−π+π−π0)=(3.3±0.6±0.6)×10−3\mathcal{B}(h_c\rightarrow K^{+}K^{-}\pi^{+}\pi^{-}\pi^{0}) =(3.3 \pm 0.6 \pm 0.6)\times 10^{-3} (the first uncertainty is statistical and the second systematical). Evidence for the decays hc→π+π−π0ηh_c\rightarrow \pi^{+} \pi^{-} \pi^{0} \eta and hc→KS0K±π∓π+π−h_c\rightarrow K^{0}_{S}K^{\pm}\pi^{\mp}\pi^{+}\pi^{-} is found with a significance of 3.6σ3.6 \sigma and 3.8σ3.8 \sigma, respectively. The corresponding branching fractions (and upper limits) are obtained to be B(hc→π+π−π0η)=(7.2±1.8±1.3)×10−3\mathcal{B}(h_c\rightarrow \pi^{+} \pi^{-} \pi^{0} \eta ) =(7.2 \pm 1.8 \pm 1.3)\times 10^{-3} (<1.8×10−2)(< 1.8 \times 10^{-2}) and B(hc→KS0K±π∓π+π−)=(2.8±0.9±0.5)×10−3\mathcal{B}(h_c\rightarrow K^{0}_{S}K^{\pm}\pi^{\mp}\pi^{+}\pi^{-}) =(2.8 \pm 0.9 \pm 0.5)\times 10^{-3} (<4.7×10−3)(<4.7\times 10^{-3}). Upper limits on the branching fractions for the final states hc→K+K−π0h_c \rightarrow K^{+}K^{-}\pi^{0}, K+K−ηK^{+}K^{-}\eta, K+K−π+π−ηK^{+}K^{-}\pi^{+}\pi^{-}\eta, 2(K+K−)π02(K^{+}K^{-})\pi^{0}, K+K−π0ηK^{+}K^{-}\pi^{0}\eta, KS0K±π∓K^{0}_{S}K^{\pm}\pi^{\mp}, and ppˉπ0π0p\bar{p}\pi^{0}\pi^{0} are determined at a confidence level of 90\%.Comment: 10 pages, 2 figure

    Study of e+e−→2(pp¯) at center-of-mass energies between 4.0 and 4.6 GeV

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    Using data taken at 23 center-of-mass energies between 4.0 and 4.6 GeV with the BESIII detector at the Beijing Electron Positron Collider and with a total integrated luminosity of approximately 15 fb-1, the process e+e-→2(pp¯) is studied for the first time. The Born cross sections for e+e-→2(pp¯) are measured, and no significant structure is observed in the lineshape. The baryon pair (pp and p¯p¯) invariant mass spectra are consistent with phase space, therefore no hexaquark or di-baryon state is found

    Measurement of the Born cross sections for e+e- →η′π+π- at center-of-mass energies between 2.00 and 3.08 GeV

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    The Born cross sections for the process e+e-→η′π+π- at different center-of-mass energies between 2.00 and 3.08 GeV are reported with improved precision from an analysis of data samples collected with the BESIII detector operating at the BEPCII storage ring. An obvious structure is observed in the Born cross section line shape. Fit as a Breit-Wigner resonance, it has a statistical significance of 6.3σ and a mass and width of M=(2111±43±25) MeV/c2 and Γ=(135±34±30) MeV, where the uncertainties are statistical and systematic, respectively. These measured resonance parameters agree with the measurements of BABAR in e+e-→η′π+π- and BESIII in e+e-→ωπ0 within two standard deviations

    Determination of the absolute branching fractions of D0→K−e+νe and D+→K¯0e+νe

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    Using 2.93 fb-1 of e+e- collision data collected with the BESIII detector at a center-of-mass energy of 3.773 GeV, we measure the absolute branching fractions of the decays D0→K-e+νe and D+→K̄0e+νe to be (3.567±0.031stat±0.025syst)% and (8.68±0.14stat±0.16syst)%, respectively. Starting with the process e+e-→DD¯, a new reconstruction method is employed to select events that contain candidates for both D→K̄e+νe and D¯→Ke-ν¯e decays. The branching fractions reported in this work are consistent within uncertainties with previous BESIII measurements that selected events containing D→K̄e+νe and hadronic D¯ decays. Combining our results with the lifetimes of the D0 and D+ mesons and the previous BESIII measurements leads to a ratio of the two decay partial widths of Γ¯D0→K-e+νeΓ¯D+→K̄0e+νe=1.039±0.021. This ratio supports isospin symmetry in the D0→K-e+νe and D+→K̄0e+νe decays within 1.9σ
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