Modèles de verre de spins à champ moyen et à interactions multiples : résultats rigoureux à basse température

We study the Ising case of the p-spin interaction mean field model for spin glasses. For large p, below the critical temperature, the configuration space naturally decomposes in a sequence of “states”. In the thermodynamic limit, the overlaps between two generic elements of any two different “states” are zero.We also construct systems that provably exhibit several phase transitions between what one might in replica theory call different levels of symmetry breaking.     

不耦合爆破技术在高应力区域卸压效果

为了研究不耦合爆破技术在巷道高应力区域的卸压原理及效果，采用室内实验和现场验证相结合的方法开展了研究。研究结果表明:在承压试件的爆破实验中，爆破对承压试件具有明显卸压作用，但由于碎胀应力的存在使爆破后应力恢复速率有所升高，因此提出爆破与排粉预裂钻孔联合卸压方法。对现场高应力区域巷道帮部卸压效果进行验证的结果表明，该方法对缓解巷道近场高应力集中具有较好效果。     

Global regularity for a class of 2D generalized tropical climate models

This paper establishes the global existence and regularity of solutions to a two-dimensional (2D) tropical climate model (TCM) with fractional dissipation. The inviscid counterpart of this model was derived by Frierson, Majda and Pauluis [8] as a model for tropical geophysical flows. This model reflects the interaction and coupling among the barotropic mode u, the first baroclinic mode v of the velocity and the temperature θ. The systems with fractional dissipation studied here may arise in the modeling of geophysical circumstances. Mathematically these systems allow simultaneous examination of a family of systems with various levels of regularization. The aim here is the global regularity with the least dissipation. We prove two main results: first, the global regularity of the system with ${(?\mathrm{\Delta })}^{\beta }v$ and ${(?\mathrm{\Delta })}^{\gamma }\theta$ for $\beta >1$ and $\beta +\gamma >\frac{3}{2}$; and second, the global regularity of the system with ${(?\mathrm{\Delta })}^{\beta }v$ for $\beta >\frac{3}{2}$. The proofs of these results are not trivial and the requirements on the fractional indices appear to be optimal. The key tools employed here include the maximal regularity for general fractional heat operators, the Littlewood–Paley decomposition and Besov space techniques, lower bounds involving fractional Laplacian and simultaneous estimates of several coupled quantities.     

Atomistic simulations of the lubricative mechanism of a nano-alkane lubricating film between two layers of Cu-Zn alloy

We describe simulations of lubrication by a hexadecane molecular lubricating film during the shearing process of a Cu-Zn alloy performed using the atomistic method. The results indicate that with increasing Zn contents, the interface slip between the alloy wall and the lubricating film first decreases and then increases, according to variations of the radius distribution function (RDF), while the interface slip reaches its lowest value of 0.12 during the shearing of CuZn30 alloy. We also discuss the relationship between interface roughness and the lubricating film. During film lubrication, the interface's roughness effectively inhibits interfacial slip. For the convex contact model, the presence of the hexadecane lubricating film reduces the interfacial contact pressure from 11.9 GPa to 8.7 GPa and the friction coefficient from 0.81 to 0.52.     

Stability of peakons for the generalized modified Camassa–Holm equation

In this paper, we study orbital stability of peakons for the generalized modified Camassa–Holm (gmCH) equation, which is a natural higher-order generalization of the modified Camassa–Holm (mCH) equation, and admits Hamiltonian form and single peakons. We first show that the single peakon is the usual weak solution of the PDEs. Some sign invariant properties and conserved densities are presented. Next, by constructing the corresponding auxiliary function $h(t,x)$ and establishing a delicate polynomial inequality relating to the two conserved densities with the maximal value of approximate solutions, the orbital stability of single peakon of the gmCH equation is verified. We introduce a new approach to prove the key inequality, which is different from that used for the mCH equation. This extends the result on the stability of peakons for the mCH equation (Qu et al. 2013) [36] successfully to the higher-order case, and is helpful to understand how higher-order nonlinearities affect the dispersion dynamics.     

Minimal silting modules and ring extensions

Science China Mathematics - Ring epimorphisms often induce silting modules and cosilting modules, termed minimal silting or minimal cosilting. The aim of this paper is twofold. Firstly, we...     

Discussion on Fractional (a,b, k)-critical Covered Graphs

Acta Mathematicae Applicatae Sinica, English Series - A graph G is called a fractional [a, b]-covered graph if for each e ∈ E(G), G contains a fractional [a, b]-factor covering e. A graph G...     

Low Temperature CO Oxidation over Co3O4 Monolithic Catalysts on a Series of Metal Foams

Kinetics and Catalysis - The monolithic catalyst was prepared by hydrothermal synthesis of Co3O4 crystals on metal foams (Ni, Cu, Fe) and named Co3O4@X. Then ZIF-67 nanoparticles were grown in situ...     

Thermal and Spectroscopic Studies of the Thermal-Oxidation Stabilities of Lubricants

Journal of Applied Spectroscopy - The influence of aromatic antioxidants 2,6-di-tert-butyl-4-methylphenol (BHT) and diphenylamine (DPA) on the thermal-oxidative degradation of base oils 150N was...