806 research outputs found
Thermocapillary migration of a deformed droplet in the combined vertical temperature gradient and thermal radiation
No full textThermocapillary migration of a deformed droplet in the combined vertical temperature gradient and thermal radiations with uniform and non uniform fluxes is first analyzed. The creeping flow solutions show that the deformed droplet has a slender or a cardioid shape, which depends on the form of the radiation flux. The deviation from a sphere depends not only on the viscosity and the conductivity ratios of two phase fluids but also on capillary and thermal radiation numbers. Moreover, in the roles of interfacial rheology on thermocapillary migration of a deformed droplet, only the surface dilatational viscosity and the surface internal energy can reduce the steady migration velocity, but the surface shear viscosity has not any effects on the steady migration velocity. The surface shear and dilatational viscosities affect the deformation of the droplet by increasing the viscosity ratio of two phase fluids. The surface internal energy directly reduces the deformation of the droplet. However, the deformed droplet still keeps its original shape without the influence of interfacial rheology. Furthermore, it is found that, based on the net force balance condition of the droplet, the normal stress balance at the interface can be used to determine the steady migration velocity, which is not affected by the surface deformation in the creeping flow. From the expressions of the normal/the tangential stress balance, it can be proved that the surface shear viscosity does not affect the steady migration velocity. The results could not only provide a valuable understanding of thermocapillary migration of a deformed droplet with/without the interfacial rheology in a vertical temperature gradient controlled by thermal radiation but also inspire its potential practical applications in microgravity and microfluidic fields.</p
Hysteresis in three-dimensional multi-layer molecularly thin-film lubrication
No full textFor three-dimensional multi-layer molecularly thin-film lubrication system with elastic substrates, roles of hysteresis on tribological properties are investigated by using the multiscale simulation method. It is found that multiple stick-slip transitions with/without hysteresis loops appear in a sliding process and form a quasi-periodic progress with lattice distance. For the few-/multi-layer thin-film lubrication system, as the load increases, the hysteresis length monotonously increases/tends to keep constant. The hysteresis is mainly caused by the relaxation of metastable states of solid atoms in the elastic substrates, which delays the system back to its equilibrium states. In the quasi-periodic shearing progress, the effective elastic coefficients and the hysteresis lengths approximately remain unchanged, which reveals that although the hysteresis loops with the same lengths appear in the sliding process, the total systematic energy is still conserved. These findings not only provide a profound understanding of roles of hysteresis in the thin-film lubrication system but also show the effects of film layers and loads on the systematic tribological properties, which are of great significance for practical applications.</p
Extension of Bertrand's theorem and factorization of the radial Schrodinger equation
No full textThe Bertrand's theorem is extended, i.e., closed orbits still may exist for central potentials other than the power law Coulomb potential and isotropic harmonic oscillator. It is shown that for the combined potential V(r) = W(r) + b/r(2) (W(r) = ar(nu)), when (and only when) W(r) is the Coulomb potential or isotropic harmonic oscillator, closed orbits still exist for suitable angular momentum. The correspondence between the closeness of classical orbits and the existence of raising and lowering operators derived from the factorization of the radial Schrodinger equation is investigated. (C) 1998 American Institute of Physics. [S0022-2488(98)00110-8].http://gateway.webofknowledge.com/gateway/Gateway.cgi?GWVersion=2&SrcApp=PARTNER_APP&SrcAuth=LinksAMR&KeyUT=WOS:000076187800011&DestLinkType=FullRecord&DestApp=ALL_WOS&UsrCustomerID=8e1609b174ce4e31116a60747a720701Physics, MathematicalSCI(E)7ARTICLE105253-52593
Multiscale Treatment of Thin-Film Lubrication
No full textA multiscale technique that combines an atomistic description of the interfacial (near) region with a coarse-grained (continuum) description of the far regions of the solid substrates is proposed. The new hybrid technique, which represents an advance over a previously proposed dynamically-constrained hybrid atomistic-coarse-grained treatment (Wu et al.J. Chem. Phys., 120, 6744, 2004), is applied to a two-dimensional model tribological system comprising planar substrates sandwiching a monolayer film. Shear–stress profiles (shear stress versus strain) computed by the new hybrid technique are in excellent agreement with “exact” profiles (i.e. those computed treating the whole system at the atomic scale)
Topological analysis of the EBL model for the chaotic NMR laser
No full textBy determining relative rotation rates of the extended Bloch-type model, a consistent topological description for the model and the chaotic NMR laser at the parameter regime investigated is indicated. A geometrical method for calculating relative rotation rates, which is different from that of constructing the template, is proposed by establishing a symbolic plane in terms of the ordering of forward, and backward sequences encoding unstable periodic orbits.http://gateway.webofknowledge.com/gateway/Gateway.cgi?GWVersion=2&SrcApp=PARTNER_APP&SrcAuth=LinksAMR&KeyUT=WOS:000076017200011&DestLinkType=FullRecord&DestApp=ALL_WOS&UsrCustomerID=8e1609b174ce4e31116a60747a720701Physics, MultidisciplinarySCI(E)1ARTICLE2225-2302
Steady thermocapillary migration of a droplet in a uniform temperature gradient combined with a radiation energy source at large Marangoni numbers
No full text
Steady thermocapillary droplet migration in a uniform temperature gradient combined with a radiation energy source at large Reynolds and Marangoni numbers is studied. To reach a terminal quasisteady process, the magnitude of the radiation energy source is required to preserve the conservative integral thermal flux across the surface. Under a quasisteady state assumption, an analytical result for the steady thermocapillary migration of a droplet at large Reynolds and Marangoni numbers is derived by using the method of matched asymptotic expansions. It is shown that the thermocapillary droplet migration speed increases as the Marangoni number increases, while a radiation energy source with a sine square dependence is provided.</p
Zb tetraquark channel and BB¯? interaction
No full text37th International Symposium on Lattice Field Theory, LATTICE 2019 -- 16 June 2019 through 22 June 2019 -- Wuhan -- 166411Two tetraquark candidates Zb(10610) and Zb(10650) with flavor structure bb ¯ du ¯ were discovered by Belle experiment in 2011. We present a preliminary Nf = 2 lattice study of the bb ¯ du ¯ system in the approximation of static b quarks, where the total spin of heavy quarks is fixed to one. The ground and the excited eigen-energies are determined as a function of separation r between b and b¯. The lower eigenstates are related to a bottomonium and a pion. One of the higher eigenstates is dominated by BB¯?: its energy is significantly below mB + mB? for r=[0.1,0.4] fm, which suggests sizable attraction. The attractive potential V(r) between B and B¯? is extracted assuming that this eigenstate is related exclusively to BB¯?. Assuming a certain form of the potential at small r < 0.1 fm and solving non-relativistic Schrodinger equation, we find a virtual bound state pole 32?+295 MeV below BB¯? threshold. This pole leads to a narrow peak in the cross-section just above threshold that could be perhaps related to experimental Zb resonances. Given all these approximations, we surprisingly find also a deep bound state 403 ±70 MeV below BB¯? threshold. If such a Zb state exists, it could be experimentally searched in the accurate dependence of rates on ?(1S)?+ invariant mass. © Copyright owned by the author(s) under the terms of the Creative Commons Attribution-NonCommercial-NoDerivatives 4.0 International License (CC BY-NC-ND 4.0).Research Agency ARRS, (J1-8137, P1-0035); TUBITAK; Deutsche Forschungsgemeinschaft, DFG; Türkiye Bilimsel ve Teknolojik Araştirma Kurumu, TÜBITA
Chromosome-level genome assembly and annotation of a potential model organism Gossypium arboreum ZB-1
No full textAbstract Recent advancements in plant regeneration and synthetic polyploid creation have been documented in Gossypium arboreum ZB-1. These developments make ZB-1 a potential model within the Gossypium genus for investigating gene function and polyploidy. This work generated the sequence and annotation of the ZB-1 genome. The contig-level genome was constructed using the PacBio high-fidelity reads, encompassing 81 contigs with an N50 length of 112.12 Mb. The Hi-C data assisted the construction of the chromosome-level genome, which consists of 13 pseudo-chromosomes and 39 un-anchored contigs, with a total length of about 1.67 Gb. Repetitive sequences accounted for about 69.7% of the genome in length. Based on ab initio and evidence-based prediction, we have identified 48,021 protein-coding genes in the ZB-1 genome. Comparative genomics analysis revealed conserved gene content and arrangement between ZB-1 and G. arboreum SXY1. The single nucleotide polymorphism occurrence rate between ZB-1 and SXY1 was about 0.54 per 1,000 nucleotides. This study enriched the genomic resources for further exploration into cotton regeneration and polyploidy mechanisms
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