32,886 research outputs found

    Public-Private Partnerships in the Electric Vehicle Charging Infrastructure in China: An Illustrative Case Study

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    © 2018 Kun Wang and Yongjian Ke. Effective supply of charging infrastructure is a necessary support for the development of electric vehicle and also an important strategic measure to promote energy consumption revolution and green development. The construction and operation of charging infrastructure in China is unfortunately not smooth, lagging behind the actual demand. Public-Private Partnerships (PPPs) may offer a promising way forward and accelerate the development of charging infrastructure by tapping the private sectors' financial resources and professional skills. However, PPP has not been commonly adopted in this sector yet. This paper hence studied an illustrative case of Anqing Project in China to demonstrate how governments structure a PPP deal in the electric vehicle charging infrastructures. A content analysis was conducted on the important project documents to investigate key elements including the planning, construction, risk sharing, profit distribution, and supervision during the execution stage. Based on the illustration, some key lessons and recommendations were provided to offer a reference for future charging infrastructure PPP projects in China

    Immunization for complex network based on the effective degree of vertex

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    The basic idea of many effective immunization strategies is first to rank the importance of vertices according to the degrees of vertices and then remove the vertices from highest importance to lowest until the network becomes disconnected. Here we define the effective degrees of vertex, i.e., the number of its connections linking to un-immunized nodes in current network during the immunization procedure, to rank the importance of vertex, and modify these strategies by using the effective degrees of vertices. Simulations on both the scale-free network models with various degree correlations and two real networks have revealed that the immunization strategies based on the effective degrees are often more effective than those based on the degrees in the initial network.Comment: 16 pages, 5 figure

    The Euler-Lagrange Cohomology and General Volume-Preserving Systems

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    We briefly introduce the conception on Euler-Lagrange cohomology groups on a symplectic manifold (M2n,ω)(\mathcal{M}^{2n}, \omega) and systematically present the general form of volume-preserving equations on the manifold from the cohomological point of view. It is shown that for every volume-preserving flow generated by these equations there is an important 2-form that plays the analog role with the Hamiltonian in the Hamilton mechanics. In addition, the ordinary canonical equations with Hamiltonian HH are included as a special case with the 2-form 1n1Hω\frac{1}{n-1} H \omega. It is studied the other volume preserving systems on (M2n,ω)({\cal M}^{2n}, \omega). It is also explored the relations between our approach and Feng-Shang's volume-preserving systems as well as the Nambu mechanics.Comment: Plain LaTeX, use packages amssymb and amscd, 15 pages, no figure

    On Silicon Carbide Grains as the Carrier of the 21 Micron Emission Feature in Post-Asymptotic Giant Branch Stars

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    The mysterious 21mu emission feature seen in 12 proto-planetary nebulae (PPNe) remains unidentified since its first detection in 1989. Over a dozen of candidate materials have been proposed within the past decade, but none of them has received general acceptance. Very recently, silicon carbide (SiC) grains with impurities were suggested to be the carrier of this enigmatic feature, based on recent laboratory data that doped SiC grains exhibit a resonance at \~21mu. This proposal gains strength from the fact that SiC is a common dust species in carbon-rich circumstellar envelopes. However, SiC dust has a strong vibrational band at ~11.3mu. We show in this Letter that in order to be consistent with the observed flux ratios of the 11.3mu feature to the 21mu feature, the band strength of the 21mu resonance has to be very strong, too strong to be consistent with current laboratory measurements. But this does not yet readily rule out the SiC hypothesis since recent experimental results have demonstrated that the 21mu resonance of doped SiC becomes stronger as the C impurity increases. Further laboratory measurements of SiC dust with high fractions of C impurity are urgently needed to test the hypothesis of SiC as the carrier of the 21mu feature.Comment: 14 pages, 3 figures, accepted for publication in ApJ

    Search for Bc(ns)B_c(ns) via the Bc(ns)Bc(ms)π+πB_c(ns)\to B_c(ms)\pi^+\pi^- transition at LHCb and Z0Z_0 factory

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    It is interesting to study the characteristics of the whole family of BcB_c which contains two different heavy flavors. LHC and the proposed Z0Z^0 factory provide an opportunity because a large database on the BcB_c family will be achieved. BcB_c and its excited states can be identified via their decay modes. As suggested by experimentalists, Bc(ns)Bc+γB_c^*(ns)\to B_c+\gamma is not easy to be clearly measured, instead, the trajectories of π+\pi^+ and π\pi^- occurring in the decay of Bc(ns)Bc(ms)+π+πB_c(ns)\to B_c(ms)+\pi^+\pi^- (n>mn>m) can be unambiguously identified, thus the measurement seems easier and more reliable, therefore this mode is more favorable at early running stage of LHCb and the proposed Z0Z^0 factory. In this work, we calculate the rate of Bc(ns)Bc(ms)+π+πB_c(ns)\to B_c(ms)+\pi^+\pi^- in terms of the QCD multipole-expansion and the numerical results indicate that the experimental measurements with the luminosity of LHC and Z0Z^0 factory are feasible.Comment: 12 pages, 1 figures and 4 tables, acceptted by SCIENCE CHINA Physics, Mechanics & Astronomy (Science in China Series G

    Organoaluminium complexes of ortho-, meta-, para-anisidines: synthesis, structural studies and ROP of ε-caprolactone (and rac-lactide)

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    Reaction of Me₃Al (two equivalents) with ortho-, meta- or para-anisidine, (OMe)(NH₂)C₆H₄, affords the complexes {[1,2-(OMe),NC₆H₄(μ-Me₂Al)](μ-Me₂Al)}₂ (1), [1,3-(Me₃AlOMe),NHC₆H₄(μ-Me₂Al)]2 (2) or [1,4-(Me₃AlOMe),NHC₆H₄(μ-Me₂Al)]₂ (3), respectively. The molecular structures of 1–3 have been determined and all three complexes were found to be highly active for the ring opening polymerization (ROP) of ε-caprolactone. 1 was found highly active either with or without benzyl alcohol present; at various temperatures, the activity order 1 > 2 ≈ 3 was observed. For the ROP of rac-lactide results for 1–3 were poor

    Evidence for surprise minimization over value maximization in choice behavior

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    Classical economic models are predicated on the idea that the ultimate aim of choice is to maximize utility or reward. In contrast, an alternative perspective highlights the fact that adaptive behavior requires agents' to model their environment and minimize surprise about the states they frequent. We propose that choice behavior can be more accurately accounted for by surprise minimization compared to reward or utility maximization alone. Minimizing surprise makes a prediction at variance with expected utility models; namely, that in addition to attaining valuable states, agents attempt to maximize the entropy over outcomes and thus 'keep their options open'. We tested this prediction using a simple binary choice paradigm and show that human decision-making is better explained by surprise minimization compared to utility maximization. Furthermore, we replicated this entropy-seeking behavior in a control task with no explicit utilities. These findings highlight a limitation of purely economic motivations in explaining choice behavior and instead emphasize the importance of belief-based motivations
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