2,519 research outputs found

    How Much Does Investment Drive Economic Growth in China?

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    Investment-driven growth has long been regarded as a key development strategy in China. This paper investigates empirically the validity of this view. Post-1990 data analyses and macroeconometric model simulations show that market demand has become a regular force in driving investment since reforms, that non-demand-driven investment growth contributes to increasing capital-output ratio far more than output growth, that government investment exerts a pivotal role in amplifying investment cycles, albeit effective in promoting employment, and that delayed and rising consumption from current investment surge can help sustain the impact of growth even with constant-returns-to-scale in the long-run GDP.Investment, Growth, Impulse response function, Cointegration, Granger non-causality

    Optimizing production scheduling of steel plate hot rolling for economic load dispatch under time-of-use electricity pricing

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    Time-of-Use (TOU) electricity pricing provides an opportunity for industrial users to cut electricity costs. Although many methods for Economic Load Dispatch (ELD) under TOU pricing in continuous industrial processing have been proposed, there are still difficulties in batch-type processing since power load units are not directly adjustable and nonlinearly depend on production planning and scheduling. In this paper, for hot rolling, a typical batch-type and energy intensive process in steel industry, a production scheduling optimization model for ELD is proposed under TOU pricing, in which the objective is to minimize electricity costs while considering penalties caused by jumps between adjacent slabs. A NSGA-II based multi-objective production scheduling algorithm is developed to obtain Pareto-optimal solutions, and then TOPSIS based multi-criteria decision-making is performed to recommend an optimal solution to facilitate filed operation. Experimental results and analyses show that the proposed method cuts electricity costs in production, especially in case of allowance for penalty score increase in a certain range. Further analyses show that the proposed method has effect on peak load regulation of power grid.Comment: 13 pages, 6 figures, 4 table

    Tree maps having chain movable fixed points

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    AbstractIn this paper we discuss some basic properties of chain reachable sets and chain equivalent sets of continuous maps. It is proved that if f:T→T is a tree map which has a chain movable fixed point v, and the chain equivalent set CE(v,f) is not contained in the set P(f) of periodic points of f, then there exists a positive integer p not greater than the number of points in the set End([CE(v,f)])−Pv(f) such that fp is turbulent, and the topological entropy h(f)⩾(log2)/p. This result generalizes the corresponding results given in Block and Coven (1986) [2], Guo et al. (2003) [6], Sun and Liu (2003) [10], Ye (2000) [11], Zhang and Zeng (2004) [12]. In addition, in this paper we also consider metric spaces which may not be trees but have open subsets U such that the closures U¯ are trees. Maps of such metric spaces which have chain movable fixed points are discussed

    Taxonomic studies on the subtribe Aphrastobraconina Ashmead (Hymenoptera: Braconidae: Braconinae) in China

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    The species of the subtribe Aphrastobraconina Ashmead from China were studied and five species belonging to three genera (Undabracon Quicke, 1986, Curriea Ashmead, 1900 and Aphrastobracon Ashmead, 1896) recognized. Three new species (Undabracon cariniventris sp. n., Aphrastobracon huanjiangensis sp. n. and A. politus sp. n.) are fully described and illustrated. The genus Undabracon (Quicke, 1986), the species Aphrastobracon flavipennis Ashmead and Curriea tibialis (Ashmead) are reported for the first time from China. A key to the species of the genus Undabracon is provided

    Energy Spectrum Theory of Incommensurate Systems

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    Due to the lack of the translational symmetry, calculating the energy spectrum of an incommensurate system has always been a theoretical challenge. Here, we propose a natural approach to generalize the energy band theory to the incommensurate systems without reliance on the commensurate approximation, thus providing a comprehensive energy spectrum theory of the incommensurate systems. Except for a truncation dependent weighting factor, the formulae of this theory are formally almost identical to that of the Bloch electrons, making it particularly suitable for complex incommensurate structures. To illustrate the application of this theory, we give three typical examples: one-dimensional bichromatic and trichromatic incommensurate potential model, as well as a moir\'{e} quasicrystal. Our theory establishes a fundamental framework for understanding the incommensurate systems.Comment: 7 pages, 3 figure

    Fixed Points of Weakly Contractive Maps and Boundedness of Orbits

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    We discuss weakly contractive maps on complete metric spaces. Following three methods of generalizing the Banach contraction principle, we obtain some fixed point theorems under some relatively weaker and more general contractive conditions
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