3,809 research outputs found

    Designing optimal urban transport strategies : the role of individual policy instruments and the impact of financial constraints

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    This paper presents a methodology for the design of optimal transport strategies and the case study results of the methodology for the City of Edinburgh, using the two multi-modal transport/land-use models MARS and TPM. First, a range of policy instruments are optimised in turn and their relative impacts explored. Second, optimisations with and without financial constraints are performed and compared. Although both models produce similar optimal policies, the relative contribution of the instruments differs between models as does the impact on outcome indicators. It is also shown that by careful design it is possible to identify a strategy which costs no more than the do-minimum but which can generate substantial additional benefits. The optimisation methodology is found to be robust, and is able to be used with different transport models, and with and without financial constraints

    Influence of agglomeration and selection effects on the Chinese construction industry

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    The determination of whether market size can influence industrial agglomeration or selection is an important topic in economic development. To analyse the differential economic development of the construction industry under different market sizes, this research analyses the employment density of China’s provinces and their Total factor productivity (TFP). It also analyses whether the difference in the provinces’ productivity are explained by their agglomeration and selection effects. First, a DEA-Malmquist model is used to calculate the TFP of each construction industry sub-sector. Then, a nested model is used to measure the influence of the selection and the agglomeration effects on the TFP at different market sizes of the construction industry. Results evidence that there are significant differences in the construction productivity at different sub-sectors in different regions of China. These differences are mainly the consequence of the agglomeration effect, rather than the selection effect. Findings of this study suggest that the Chinese construction industry should optimise its structure in different provinces to achieve a balanced growth at different market sizes

    The Networked Common Goods Game

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    We introduce a new class of games called the networked common goods game (NCGG), which generalizes the well-known common goods game. We focus on a fairly general subclass of the game where each agent's utility functions are the same across all goods the agent is entitled to and satisfy certain natural properties (diminishing return and smoothness). We give a comprehensive set of technical results listed as follows. * We show the optimization problem faced by a single agent can be solved efficiently in this subclass. The discrete version of the problem is however NP-hard but admits an fully polynomial time approximation scheme (FPTAS). * We show uniqueness results of pure strategy Nash equilibrium of NCGG, and that the equilibrium is fully characterized by the structure of the network and independent of the choices and combinations of agent utility functions. * We show NCGG is a potential game, and give an implementation of best/better response Nash dynamics that lead to fast convergence to an ϵ\epsilon-approximate pure strategy Nash equilibrium. * Lastly, we show the price of anarchy of NCGG can be as large as Ω(n1ϵ)\Omega(n^{1-\epsilon}) (for any ϵ>0\epsilon>0), which means selfish behavior in NCGG can lead to extremely inefficient social outcomes

    Complete two-loop effective potential approximation to the lightest Higgs scalar boson mass in supersymmetry

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    I present a method for accurately calculating the pole mass of the lightest Higgs scalar boson in supersymmetric extensions of the Standard Model, using a mass-independent renormalization scheme. The Higgs scalar self-energies are approximated by supplementing the exact one-loop results with the second derivatives of the complete two-loop effective potential in Landau gauge. I discuss the dependence of this approximation on the choice of renormalization scale, and note the existence of particularly poor choices which fortunately can be easily identified and avoided. For typical input parameters, the variation in the calculated Higgs mass over a wide range of renormalization scales is found to be of order a few hundred MeV or less, and is significantly improved over previous approximations.Comment: 5 pages, 1 figure. References added, sample test model parameters listed, minor wording change

    Exact and Approximate Formulas for Neutrino Mixing and Oscillations with Non-Standard Interactions

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    We present, both exactly and approximately, a complete set of mappings between the vacuum (or fundamental) leptonic mixing parameters and the effective ones in matter with non-standard neutrino interaction (NSI) effects included. Within the three-flavor neutrino framework and a constant matter density profile, a full set of sum rules is established, which enables us to reconstruct the moduli of the effective leptonic mixing matrix elements, in terms of the vacuum mixing parameters in order to reproduce the neutrino oscillation probabilities for future long-baseline experiments. Very compact, but quite accurate, approximate mappings are obtained based on series expansions in the neutrino mass hierarchy parameter \eta \equiv \Delta m^2_{21}/\Delta m^2_{31}, the vacuum leptonic mixing parameter s_{13} \equiv \sin\theta_{13}, and the NSI parameters \epsilon_{\alpha\beta}. A detailed numerical analysis about how the NSIs affect the smallest leptonic mixing angle \theta_{13}, the deviation of the leptonic mixing angle \theta_{23} from its maximal mixing value, and the transition probabilities useful for future experiments are performed using our analytical results.Comment: 29 pages, 8 figures, final version published in J. High Energy Phy

    The Stability of Differential Systems with Delay

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    A new criterion for the stability of differential delay systems is proved in terms of a matrix of parameters

    Periodic Solutions of Differential Equations

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    In this paper, we study the existence of periodic solutions of neutral differential equations with infinite delay and delay equations of nth order. Some necessary and sufficient conditions for existence of periodic solutions are obtained

    K-Exponential Stability of Non-Linear Delay Systems

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    In this paper we introduce a new concept of k-exponential stability. The k-exponential stability of non-linear delay systems is investigated via the non-linear variation of parameters formula and non-linear inequality analysis
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