518 research outputs found

    Characterizations of Nonemptiness and Compactness of the Set of Weakly Efficient Solutions for Convex Vector Optimization and Applications

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    AbstractIn this paper, we give characterizations for the nonemptiness and compactness of the set of weakly efficient solutions of an unconstrained/constrained convex vector optimization problem with extended vector-valued functions in terms of the 0-coercivity of some scalar functions. Finally, we apply these results to discuss solution characterizations of a constrained convex vector optimization problem in terms of solutions of a sequence of unconstrained vector optimization problems which are constructed with a general nonlinear Lagrangian

    Multi-neutron transfer coupling in sub-barrier 32S+90,96Zr fusion reactions

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    The role of neutron transfers is investigated in the fusion process below the Coulomb barrier by analyzing 32S+90Zr and 32S+96Zr as benchmark reactions. A full coupled-channel calculation of the fusion excitation functions has been performed for both systems by using multi-neutron transfer coupling for the more neutron-rich reaction. The enhancement of fusion cross sections for 32S+96Zr is well reproduced at sub-barrier energies by NTFus code calculations including the coupling of the neutron-transfer channels following the Zagrebaev semiclassical model. We found similar effects for 40Ca+90Zr and 40Ca+96Zr fusion excitation functions.Comment: Minor corrections, 11 pages, 4 figures, Fusion11 Conference, Saint Malo, France, 2-6 mai 201

    A self-consistent method to analyze the effects of the positive Q-value neutron transfers on fusion

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    AbstractConsidering the present limitation of the need for external parameters to describe the nucleus–nucleus potential and the couplings in the coupled-channels calculations, this work introduces an improved method without adjustable parameter to overcome the limitation and then sort out the positive Q-value neutron transfers (PQNT) effects based on the CCFULL calculations. The corresponding analysis for Ca+Ca, S,Ca+Sn, and S,Ca+Zr provides a reliable proof and a quantitative evaluation for the residual enhancement (RE) related to PQNT. In addition, the RE for S32,Ca40+Zr94 shows an unexpected larger enhancement than S32,Ca40+Zr96 despite the similar multi-neutron transfer Q-values. This method should rather strictly test the fusion models and be helpful for excavating the underlying physics

    Geometric Phase and Quantum Phase Transition in the Lipkin-Meshkov-Glick model

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    The relation between the geometric phase and quantum phase transition has been discussed in the Lipkin-Meshkov-Glick model. Our calculation shows the ability of geometric phase of the ground state to mark quantum phase transition in this model. The possibility of the geometric phase or its derivatives as the universal order parameter of characterizing quantum phase transitions has been also discussed.Comment: 6 pages and to be published in Phys.Lett.

    Interference between the halves of a double-well trap containing a Bose-Einstein condensate

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    Interference between the halves of a double-well trap containing a Bose-Einstein condensate is studied. It is found that when the atoms in the two wells are initially in the coherent state, the intensity exhibits collapses and revivals, but it does not for the initial Fock states. Whether the initial states are in the coherent states or in a Fock states, the fidelity time has nothing to do with collision. We point out that interference and its fidelity can be adjusted experimentally by properly preparing the number and initial states of the system.Comment: 10 pages, 3 figures, accepted by Phy. rev.

    Non-Markovian dynamics in a spin star system: The failure of thermalization

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    In most cases, a small system weakly interacting with a thermal bath will finally reach the thermal state with the temperature of the bath. We show that this intuitive picture is not always true by a spin star model where non-Markov effect predominates in the whole dynamical process. The spin star system consists a central spin homogeneously interacting with an ensemble of identical noninteracting spins. We find that the correlation time of the bath is infinite, which implies that the bath has a perfect memory, and that the dynamical evolution of the central spin must be non- Markovian. A direct consequence is that the final state of the central spin is not the thermal state equilibrium with the bath, but a steady state which depends on its initial state.Comment: 8 page

    Tightly Coupled Array Antennas for Ultra-Wideband Wireless Systems

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    Tightly coupled array (TCA) antenna has become a hot topic of research recently, due to its potential of enabling one single antenna array to operate over an extremely wide frequency range. Such an array antenna is promising for applications in numerous wideband/multi-band and multi-function wireless systems such as wideband high-resolution radars, 5G mobile communications, satellite communications, global navigation satellite systems, sensors, wireless power transmission, internet of things and so on. Many papers on this topic have been published by researchers internationally. This paper provides a detailed review of the recent development on TCA that utilizes the capacitive coupling. The basic principles and the historical evolution of the TCAs are introduced firstly. Then, recent development in the analysis and design of TCAs, such as equivalent circuit analysis, bandwidth limitation analysis, array elements, feed structures, substrates/superstrates loading, etc., are explained and discussed. The performances of the state-of-the-art TCAs are presented and a comparison amongst some TCAs reported recently is summarized and discussed. To illustrate the practical designs of TCA, one case study is provided, and the detailed design procedures of the TCA are explained so as to demonstrate the TCA design methodology. Simulated results including the VSWR at different angles of scanning, patterns and antenna gain are shown and discussed. A conclusion and future work are given in the end

    Colletotrichum species associated with anthracnose of Pyrus spp. in China

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    Colletotrichum species are plant pathogens, saprobes, and endophytes on a range of economically important hosts. However, the species occurring on pear remain largely unresolved. To determine the morphology, phylogeny and biology of Colletotrichum species associated with Pyrus plants, a total of 295 samples were collected from cultivated pear species (including P. pyrifolia, P. bretschneideri, and P. communis) from seven major pear-cultivation provinces in China. The pear leaves and fruits affected by anthracnose were sampled and subjected to fungus isolation, resulting in a total of 488 Colletotrichum isolates. Phylogenetic analyses based on six loci (ACT, TUB2, CAL, CHS-1, GAPDH, and ITS) coupled with morphology of 90 representative isolates revealed that they belong to 10 known Colletotrichum species, including C. aenigma, C. citricola, C. conoides, C. fioriniae, C. fructicola, C. gloeosporioides, C. karstii, C. plurivorum, C. siamense, C. wuxiense, and two novel species, described here as C. jinshuiense and C. pyrifoliae. Of these, C. fructicola was the most dominant, occurring on P. pyrifolia and P. bretschneideri in all surveyed provinces except in Shandong, where C. siamense was dominant. In contrast, only C. siamense and C. fioriniae were isolated from P. communis, with the former being dominant. In order to prove Koch's postulates, pathogenicity tests on pear leaves and fruits revealed a broad diversity in pathogenicity and aggressiveness among the species and isolates, of which C. citricola, C. jinshuiense, C. pyrifoliae, and C. conoides appeared to be organ-specific on either leaves or fruits. This study also represents the first reports of C. citricola, C. conoides, C. karstii, C. plurivorum, C. siamense, and C. wuxiense causing anthracnose on pear.Earmarked Fundhttps://www.ingentaconnect.com/content/nhn/pimjhj2020BiochemistryForestry and Agricultural Biotechnology Institute (FABI)GeneticsMicrobiology and Plant Patholog

    High Altitude test of RPCs for the ARGO-YBJ experiment

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    A 50 m**2 RPC carpet was operated at the YangBaJing Cosmic Ray Laboratory (Tibet) located 4300 m a.s.l. The performance of RPCs in detecting Extensive Air Showers was studied. Efficiency and time resolution measurements at the pressure and temperature conditions typical of high mountain laboratories, are reported.Comment: 16 pages, 10 figures, submitted to Nucl. Instr. Met
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