Phonon Effects on Spin-Charge Separation in One Dimension

Phonon effects on spin-charge separation in one dimension are investigated through the calculation of one-electron spectral functions in terms of the recently developed cluster perturbation theory together with an optimized phonon approach. It is found that the retardation effect due to the finiteness of phonon frequency suppresses the spin-charge separation and eventually makes it invisible in the spectral function. By comparing our results with experimental data of TTF-TCNQ, it is observed that the electron-phonon interaction must be taken into account when interpreting the ARPES data.Comment: 5 pages, 5 figures, minor differences with the published version in Physical Review Letter

Plurality in Naxi and its typological implications

Plurality in Naxi can be explicitly expressed by suffixation or tone change on common nouns denoting human beings. This paper complements the published literature in providing a detailed description of its morpho-syntax and semantics of plurality. It shows that Naxi belongs to the typologically rare type of language in which the coding of plurality and definiteness is in one morpheme, the other three languages known to date to have this property are Chinese, Khmer and Maori. Evidence for the definiteness property of explicit plurality comes from it being excluded in syntactic environments in which definiteness noun phrases are ruled out. It is argued that the empirical basis of Greenberg’s (1974) generalization regarding the relation between numeral classifiers and compulsory expression of nominal plurality is subject to the interpretation of explicit expression of plurality. If it is taken to embody in a morpheme (or a set of morphemes) specifically for expressing plurality, then Naxi is consistent with Greenberg’s claim that languages with numeral classifiers do not have compulsory expression of plurality on nouns.Australian National Universit

Beijing converters: bridge converters with a capacitor added to reduce leakage currents, DC-bus voltage ripples, and total capacitance required

Abstract: Isolation transformers and bulky electrolytic capacitors are often used in power electronic converters to reduce leakage currents and voltage ripples but this leads to low power density and reduced reliability. In this paper, an auxiliary capacitor is added to the widely used conventional full-bridge converter to provide a path for, and hence significantly reduce, the leakage current. The operation of the full-bridge converter is split into the operation of a half-bridge converter and a dc-dc converter so that the ripple energy can be diverted from the dc-bus capacitor to the auxiliary capacitor. Hence, the dc-bus capacitor can be significantly reduced while maintaining very low voltage ripples on the dc bus because it is only required to filter out switching ripples. The auxiliary capacitor is designed to allow high voltage ripples because its voltage is not supplied to any load. Accordingly, the auxiliary capacitor can also be very small as well. As a result, the total required capacitance becomes very small. The reduction ratio of the total capacitance is significant, which makes it cost-effective to use film capacitors instead of electrolytic capacitors. The proposed converters can be also operated as an inverter without any restriction on power factor because the adopted four switches are all bidirectional in terms of power flow. Experimental results for both rectification and inversion modes are presented to demonstrate the performance of the proposed converter in reducing the ripples, the leakage currents, and the total capacitance needed, with comparison to the conventional bridge converter without the auxiliary capacitor

Perfect crossed Andreev reflection in the proximitized graphene/superconductor/proximitized graphene junctions

We study the crossed Andreev reflection and the nonlocal transport in the proximitized graphene/supercondcutor/proximitized graphene junctions with the pseudospin staggered potential and the intrinsic spin-orbit coupling. The crossed Andreev reflection with the local Andreev reflection and the elastic cotunneling being completely eliminated can be realized for the electrons with the specific spin-valley index when the intrinsic spin-orbit couplings in the left graphene and the right graphene possess the opposite sign. The perfect crossed Andreev reflection with its probability equal to $100\%$ can be obtained in the space consisting of the incident angle and the energy of the electrons. The crossed conductance and its oscillation with the superconductor length are also investigated. The energy ranges for the crossed Andreev reflection without the local Andreev reflection and the elastic cotunneling are clarified for the different magnitudes of the pseudospin potential and the spin-orbit coupling. The spin-valley index of the electrons responsible for the perfect crossed Andreev reflection can be switched by changing the sign of the intrinsic spin-orbit coupling or exchanging the biases applied on the left graphene and the right graphene. Our results are helpful for designing the flexible and high-efficiency Cooper pair splitter based on the spin-valley degree of freedom.Comment: 9 pages,4 figure

Problem Frame Analysis of Weapon System of Systems Requirement

AbstractThe requirement of weapon system of systems(WSoS) plays a very important role in the development of WSoS,which is the basis of the design of WSoS and runs through the research of WSoS. Based on the requirement engineering method of problem frame, the problem frame of WSoS requirement(WSoSR) is built which is consisted of requirement, mission domain, task domain, operation domain and system of systems(SoS) domain. The phenomena between the domains is defined and the constraint set is given. The model of the WSoSR problem transformation is put forward including the transformation process and the transformation content. An example of combined firing employment to the enemy ship fleet is shown in the end