379 research outputs found

    Threshold image target segmentation technology based on intelligent algorithms

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    This paper briefly introduces the optimal threshold calculation model and particle swarm optimization (PSO) algorithm for image segmentation and improves the PSO algorithm. Then the standard PSO algorithm and improved PSO algorithm were used in MATLAB software to make simulation analysis on image segmentation. The results show that the improved PSO algorithm converges faster and has higher fitness value; after the calculation of the two algorithms, it is found that the improved PSO algorithm is better in the subjective perspective, and the image obtained by the improved PSO segmentation has higher regional consistency and takes shorter time in the perspective of quantitative objective data. In conclusion, the improved PSO algorithm is effective in image segmentation

    Orientations of two coupled molecules

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    Orientation states of two coupled polar molecules controlled by laser pulses are studied theoretically. By varying the period of a series of periodically applied laser pulse, transition from regular to chaotic behavior may occur. Schmidt decomposition is used to measure the degree of entanglement. It is found that the entanglement can be enhanced by increasing the strength of laser pulse.Comment: 4 pages, 4 figures, to appear in Chem. Phys. Lett.(2004

    Selective crystallisation of carbamazepine polymorphs on surfaces with differing properties

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    Surface-induced nucleation of carbamazepine (CBZ) in ethanol was investigated with different surface materials: glass, polytetrafluoroethylene (PTFE) and tin. The introduction of foreign surfaces with different areas and surface chemistries into the solution has an impact on the crystal morphology and polymorphic form (Form II or III). With an increase in supersaturation, a higher possibility of crystallisation of CBZ metastable Form II was observed, as expected. Increasing the number of inserts resulted in a direct increase in the surface area available for heterogeneous nucleation. The increase in surface area resulted in the greater possibility of obtaining the metastable Form II of CBZ. The stable Form III preferred to nucleate on tin rather than on glass and PTFE. The results indicate that the two different polymorphs of CBZ can be selectively crystallised out from solution with the aid of a foreign surface. The kinetic mechanism of heterogeneous nucleation of the different polymorphs induced by foreign surfaces was discussed. The potential applications will be used to control and design the crystallisation process

    Nonfactorizable contributions to BD()MB \to D^{(*)} M decays

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    While the factorization assumption works well for many two-body nonleptonic BB meson decay modes, the recent measurement of BˉD()0M0\bar B\to D^{(*)0}M^0 with M=πM=\pi, ρ\rho and ω\omega shows large deviation from this assumption. We analyze the BD()MB\to D^{(*)}M decays in the perturbative QCD approach based on kTk_T factorization theorem, in which both factorizable and nonfactorizable contributions can be calculated in the same framework. Our predictions for the Bauer-Stech-Wirbel parameters, a2/a1=0.43±0.04|a_2/a_1|= 0.43\pm 0.04 and Arg(a2/a1)42Arg(a_2/a_1)\sim -42^\circ and a2/a1=0.47±0.05|a_2/a_1|= 0.47\pm 0.05 and Arg(a2/a1)41Arg(a_2/a_1)\sim -41^\circ, are consistent with the observed BDπB\to D\pi and BDπB\to D^*\pi branching ratios, respectively. It is found that the large magnitude a2|a_2| and the large relative phase between a2a_2 and a1a_1 come from color-suppressed nonfactorizable amplitudes. Our predictions for the Bˉ0D()0ρ0{\bar B}^0\to D^{(*)0}\rho^0, D()0ωD^{(*)0}\omega branching ratios can be confronted with future experimental data.Comment: 25 pages with Latex, axodraw.sty, 6 figures and 5 tables, Version published in PRD, Added new section 5 and reference

    Two-to-one resonant multi-modal dynamics of horizontal/inclined cables. Part I : theoretical formulation and model validation

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    This paper is first of the two papers dealingwith analytical investigation of resonant multimodal dynamics due to 2:1 internal resonances in the finite-amplitude free vibrations of horizontal/inclined cables. Part I deals with theoretical formulation and validation of the general cable model. Approximate nonlinear partial differential equations of 3-D coupled motion of small sagged cables - which account for both spatio-temporal variation of nonlinear dynamic tension and system asymmetry due to inclined sagged configurations - are presented. A multidimensional Galerkin expansion of the solution ofnonplanar/planar motion is performed, yielding a complete set of system quadratic/cubic coefficients. With the aim of parametrically studying the behavior of horizontal/inclined cables in Part II [25], a second-order asymptotic analysis under planar 2:1 resonance is accomplished by the method of multiple scales. On accounting for higher-order effectsof quadratic/cubic nonlinearities, approximate closed form solutions of nonlinear amplitudes, frequencies and dynamic configurations of resonant nonlinear normal modes reveal the dependence of cable response on resonant/nonresonant modal contributions. Depending on simplifying kinematic modeling and assigned system parameters, approximate horizontal/inclined cable models are thoroughly validated by numerically evaluating statics and non-planar/planar linear/non-linear dynamics against those of the exact model. Moreover, the modal coupling role and contribution of system longitudinal dynamics are discussed for horizontal cables, showing some meaningful effects due to kinematic condensation

    Weak decays of J/ψJ/\psi: the non-leptonic case

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    In our previous study, we calculated the transition from factors of J/ψD(s)()J/\psi\to D^{(*)}_{(s)} using the QCD sum rules. Based on the factorization approximation, the obtained form factors can be applied to evaluate the weak non-leptonic decay rates of J/ψD(s)()+MJ/\psi\to D^{(*)}_{(s)}+M, where MM stands for a light pseudoscalar or vector meson. We predict that the branching ratio for inclusive non-leptonic two-body weak decays of J/ψJ/\psi which are realized via the spectator mechanism, can be as large as 1.3×1081.3 \times 10^{-8}, in particular, the branching ratio of J/ψDs±+ρJ/\psi\to D^{*\pm}_s+\rho^\mp can reach 5.3×1095.3 \times 10^{-9}. Such values will be marginally accessed by the ability of BESIII which will begin running very soon.Comment: 16 pages, revTex4, 1 figur

    The transition form factors for semi-leptonic weak decays of J/ψJ/\psi in QCD sum rules

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    Within the Standard Model, we investigate the semi-leptonic weak decays of J/ψJ/\psi. The various form factors of J/ψJ/\psi transiting to a single charmed meson (D(d,s)()D^{(*)}_{(d,s)}) are studied in the framework of the QCD sum rules. These form factors fully determine the rates of the weak semi-leptonic decays of J/ψJ/\psi and provide valuable information about the non-perturbative QCD effects. Our results indicate that the decay rate of the semi-leptonic weak decay mode J/ψDs()+e++νeJ/\psi \to D^{(*)-}_{s}+e^{+}+\nu_{e} is at order of 101010^{-10}.Comment: 28 pages, 6 figures, revised version to be published in Eur.Phys.J.

    A Measurement of Psi(2S) Resonance Parameters

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    Cross sections for e+e- to hadons, pi+pi- J/Psi, and mu+mu- have been measured in the vicinity of the Psi(2S) resonance using the BESII detector operated at the BEPC. The Psi(2S) total width; partial widths to hadrons, pi+pi- J/Psi, muons; and corresponding branching fractions have been determined to be Gamma(total)= (264+-27) keV; Gamma(hadron)= (258+-26) keV, Gamma(mu)= (2.44+-0.21) keV, and Gamma(pi+pi- J/Psi)= (85+-8.7) keV; and Br(hadron)= (97.79+-0.15)%, Br(pi+pi- J/Psi)= (32+-1.4)%, Br(mu)= (0.93+-0.08)%, respectively.Comment: 8 pages, 6 figure

    Measurements of the observed cross sections for e+ee^+e^-\to exclusive light hadrons containing π0π0\pi^0\pi^0 at s=3.773\sqrt s= 3.773, 3.650 and 3.6648 GeV

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    By analyzing the data sets of 17.3, 6.5 and 1.0 pb1^{-1} taken, respectively, at s=3.773\sqrt s= 3.773, 3.650 and 3.6648 GeV with the BES-II detector at the BEPC collider, we measure the observed cross sections for e+eπ+ππ0π0e^+e^-\to \pi^+\pi^-\pi^0\pi^0, K+Kπ0π0K^+K^-\pi^0\pi^0, 2(π+ππ0)2(\pi^+\pi^-\pi^0), K+Kπ+ππ0π0K^+K^-\pi^+\pi^-\pi^0\pi^0 and 3(π+π)π0π03(\pi^+\pi^-)\pi^0\pi^0 at the three energy points. Based on these cross sections we set the upper limits on the observed cross sections and the branching fractions for ψ(3770)\psi(3770) decay into these final states at 90% C.L..Comment: 7 pages, 2 figure

    Partial wave analysis of J/\psi \to \gamma \phi \phi

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    Using 5.8×107J/ψ5.8 \times 10^7 J/\psi events collected in the BESII detector, the radiative decay J/ψγϕϕγK+KKS0KL0J/\psi \to \gamma \phi \phi \to \gamma K^+ K^- K^0_S K^0_L is studied. The ϕϕ\phi\phi invariant mass distribution exhibits a near-threshold enhancement that peaks around 2.24 GeV/c2c^{2}. A partial wave analysis shows that the structure is dominated by a 0+0^{-+} state (η(2225)\eta(2225)) with a mass of 2.240.02+0.030.02+0.032.24^{+0.03}_{-0.02}{}^{+0.03}_{-0.02} GeV/c2c^{2} and a width of 0.19±0.030.04+0.060.19 \pm 0.03^{+0.06}_{-0.04} GeV/c2c^{2}. The product branching fraction is: Br(J/ψγη(2225))Br(η(2225)ϕϕ)=(4.4±0.4±0.8)×104Br(J/\psi \to \gamma \eta(2225))\cdot Br(\eta(2225)\to \phi\phi) = (4.4 \pm 0.4 \pm 0.8)\times 10^{-4}.Comment: 11 pages, 4 figures. corrected proof for journa
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