2,110 research outputs found
Measurement of the current and spectral analysis on the continental shelf in the East China Sea
No full textFloer cohomology of Lagrangian intersections and pseudo-holomorphic disks. I.Addendum
No full textThis is an addendum to the author's earlier paper ''Floer Cohomology of Lagrangian Intersection and Pseudo-Holomorphic Discs, I,'' Comm. Pure Appl. Math. 46, 1993, pp. 949-993. The main result of this addendum extends the definition of the Fleer cohomology of Lagrangian intersection to the case where the minimal Maslov number is equal to 2. (C) 1996 John Wiley & Sons, Inc.X1145sciescopu
Plastic Effect on the Sliding Inception Between a Cylinder and a Rigid Flat
No full textThe effects of material plasticity and local slip on the sliding inception of asperity are studied in the present work. Firstly, a semi-analytical solution is derived under the full-stick condition to analyze the effect of material plasticity on sliding friction. Then, a friction model with contact stiffness criterion is proposed to study the cases from partial-slip condition to full-stick condition. Finite element simulations with the provided model are used to present the friction map. The friction coefficient of full-stick interface converges at a stable value, approximately 0.3. Plasticity saturation appears as the normalized contact interference is larger than 3. A transition mechanism from slip-dominated to yield-dominated takes place in the sliding process. The simulation results are compared with the semi-analytical solution.</p
Spectral invariants and the length minimizing property of Hamiltonian paths
No full textIn this paper we provide a criterion for the quasi-autonomous Hamiltonian path ("Hofer's geodesic") on arbitrary closed symplectic manifolds (M, omega) to be length minimizing in its homotopy class in terms of the spectral invariants rho(G; 1) that the author has recently constructed. As an application, we prove that any autonomous Hamiltonian path on arbitrary closed symplectic manifolds is length minimizing in its homotopy class with fixed ends, as long as it has no contractible periodic orbits of period one and it has a maximum and a minimum that are generically under-twisted, and all of its critical points are non-degenerate in the Floer theoretic sense.X1110sci
Antiferromagnetic and topological states in silicene: A mean field study
No full textIt has been widely accepted that silicene is a topological insulator, and its gap closes first and then opens again with increasing electric field, which indicates a topological phase transition from the quantum spin Hall state to the band insulator state. However, due to the relatively large atomic spacing of silicene, which reduces the bandwidth, the electron-electron interaction in this system is considerably strong and cannot be ignored. The Hubbard interaction, intrinsic spin orbital coupling (SOC), and electric field are taken into consideration in our tight-binding model, with which the phase diagram of silicene is carefully investigated on the mean field level. We have found that when the magnitudes of the two mass terms produced by the Hubbard interaction and electric potential are close to each other, the intrinsic SOC flips the sign of the mass term at either K or K' for one spin and leads to the emergence of the spin-polarized quantum anomalous Hall state
Floer mini-max theory, the Cerf diagram, and the spectral invariants
No full textThe author previously defined the spectral invariants, denoted by rho(H; a), of a Hamiltonian function H as the mini-max value of the action functional A(H) over the Novikov Floer cycles in the Floer homology class dual to the quantum cohomology class a. The spectrality axiom of the invariant rho(H; a) states that the mini-max value is a critical value of the action functional AH. The main purpose of the present paper is to prove this axiom for nondegenerate Hamiltonian functions in irrational symplectic manifolds (M, omega). We also prove that the spectral invariant function rho(a) : H (sic) rho(H; a) can be pushed down to a continuous function defined on the universal (etale) covering space (sic)(M,omega) of the group Ham(M,omega) of Hamiltonian diffeomorphisms on general (M, omega). For a certain generic homotopy, which we call a Cerf homotopy H = {H(s)}(0 <= s <= 1) of Hamiltonians, the function rho(a) circle H : s (sic) rho(H(s); a) is piecewise smooth away from a countable subset of [0,1] for each non-zero quantum cohomology class a. The proof of this nondegenerate spectrality relies on several new ingredients in the chain level Floer theory, which have their own independent interest: a structure theorem on the Cerf bifurcation diagram of the critical values of the action functionals associated to a generic one-parameter family of Hamiltonian functions, a general structure theorem and the handle sliding lemma of Novikov Floer cycles over such a family and a family version. of new transversality statements involving the Floer chain map, and many others. We call this chain level Floer theory as a whole the Floer mini-max theory.X118sciescopuskc
Continuous Hamiltonian dynamics and area-preserving homeomorphism group of D2
Full text linkThe main purpose of this paper is to propose a scheme of a proof of the nonsimpleness of the group {\rm Homeo}^\Omega(D^2,\del D^2) of area preserving homeomorphisms of the 2-disc . We first establish the existence of Alexander isotopy in the category of Hamiltonian homeomorphisms. This reduces the question of extendability of the well-known Calabi homomorphism \Cal: {\rm Diff}^\Omega(D^1,\del D^2) \to \R to a homomorphism \overline \Cal: {\rm Hameo(}D^2,\del D^2) \to \R to that of the vanishing of the basic phase function , a Floer theoretic graph selector constructed in \cite{oh:jdg}, that is associated to the graph of the topological Hamiltonian loop and its normalized Hamiltonian on that is obtained via the natural embedding . Here {\rm Hameo(}D^2,\del D^2) is the group of Hamiltonian homeomorphisms introduced by M\"uller and the author \cite{oh:hameo1}. We then provide an evidence of this vanishing conjecture by proving the conjecture for the special class of \emph{weakly graphical} topological Hamiltonian loops on via a study of the associated Hamiton-Jacobi equation.1111Ysciescopuskc
Identification, fermentation optimization, and biocontrol efficacy of actinomycete YG-5 for the prevention of Alternaria leaf spot disease in star anise
No full textAbstract Star anise (Illicium verum), a valuable spice tree, faces significant threats from fungal diseases, particularly Alternaria leaf spot. This study investigates the potential of a soil-derived actinomycete strain, YG-5, as a biocontrol agent against Alternaria tenuissima, the causative pathogen on Alternaria leaf spot in star anise. Through comprehensive morphology, physiology, biochemistry, and genetic analyses, we identified the isolate as Streptomyces sp. YG-5. The strain exhibited broad-spectrum antimicrobial activity against several plant pathogens, with inhibition rates ranging between 36.47 to 80.34%. We systematically optimized the fermentation conditions for YG-5, including medium composition and cultivation parameters. The optimized process resulted in an 89.56% inhibition rate against A. tenuissima, a 14.72% improvement over non-optimized conditions. Notably, the antimicrobial compounds produced by YG-5 demonstrated stability across various temperatures, pH levels, and UV irradiation. In vivo efficacy trials showed promising results, with YG-5 fermentation broth reducing Alternaria leaf spot incidence on star anise leaves by 56.95%. These findings suggest that Streptomyces sp. YG-5 holds significant potential as a biocontrol agent against Alternaria leaf spot in star anise cultivation, offering a sustainable approach to disease management in this valuable crop
Geochronology, petrology and geochemistry of the granulite xenoliths from Nushan, east China: Implication for a heterogeneous lower crust beneath the Sino-Korean Craton
No full textInterference effect on friction behavior of asperities on single crystal copper
No full textBy using Green function molecular dynamics method, we systematically study the friction behavior of a single asperity and asperity array over the (1 1 1) surface of single crystal copper. We find that internal plastic behavior (burst of stacking faults, dislocation emission and propagation) is a promising reason for the higher value of static friction coefficient than that of dynamics friction in non-adhesive scratch. For the rough surface, however, the difference between static and dynamic friction coefficients disappear due to the interference between asperities. The interference dramatically increases the friction coefficient by introducing atomic scale plastic features (pile-up atoms, stacking faults, and U-shape dislocation loop). (C) 2014 Elsevier Ltd. All rights reserved
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