Experiments show that vacancies in solids may coalesce into voids and self-organize into a superlattice. The voids have diameters around 10 nm and spacing of tens of nanometers. This paper develops a phase-field model to study this behavior, which incorporates the free energy of mixing, interfacial energy and elastic energy. Vacancy diffusion is described by a Cahn–Hilliard type nonlinear diffu...

We suggest a scalar model for deformation and flow of an amorphous material such as a foam or an emulsion. To describe elastic, plastic and viscous behaviours, we use three scalar variables: elastic deformation, plastic deformation rate and total deformation rate; and three material-specific parameters: shear modulus, yield deformation and viscosity. We obtain equations valid for different type...

A statistical theory of cholesteric liquid crystals composed of short rigid biaxial molecules is presented. It is derived in the thermodynamic limit at a small density and a small twist. The uniaxial (biaxial) cholesteric phase is regarded as a distorted form of the uniaxial (biaxial) nematic phase. The chirality of the interactions and the implementation of the inversion to the rotation matrix...

Recently, rod theory has been applied to the mathematical modeling of bacterial fibers and biopolymers (e.g. DNA), to study their mechanical properties and shapes (e.g. supercoiling). In static rod theory, an elastic rod in equilibrium is the critical point of an elastic energy. This induces a natural question of how to find elasticae. In this paper, we focus on how to find the critical points ...

The spin-flavor structure of certain nucleon-nucleon scattering observables derived from the large Nc limit of QCD in the kinematical regime where time-dependent mean-field theory is valid is discussed. In previous work [1] this regime was taken to be where the external momentum was of order Nc which precluded the study of differential cross sections in elastic scattering. Here it is shown that...

We study the mechanics of a reversible decohesion (unzipping) of an elastic layer subjected to quasi-static end-point loading. At the micro level the system is simulated by an elastic chain of particles interacting with a rigid foundation through breakable springs. Such system can be viewed as prototypical for the description of a wide range of phenomena from peeling of polymeric tapes, to roll...

Air-pressure limit value is an important conditional parameter of artificial respiration. The pulmonary characteristics are very different according to the person. For setting appropriate ventilation conditions fitting to each patient, it is necessary to establish a mathematical model describing the mechanism of human respiratory system, and to know the pulmonary characteristic of each patient ...

This paper first considers the approximation of peridynamics by strain-gradient models in the linear, one-dimensional setting. Strain-gradient expansions that approximate the peridynamic dispersion relation using Taylor series are compared to strain-gradient models that approximate the peridynamic elastic energy. The dynamic and energetic expansions differ from each other, and neither captures ...

In this article, we consider the Qian–Sheng model in Landau–de Gennes framework describing nematic liquid crystal flows when inertial effect is neglected. By taking limit of elastic constant to zero (also called uniaxial limit) and utilizing so-called Hilbert expansion method, provide a rigorous derivation from non-inertial Ericksen–Leslie model.

P–wave amplitudes for elastic KK photoproduction on hydrogen near the φ(1020) resonance have been derived in an analytical form and a partial wave decomposition of the amplitudes has been performed. We discuss the high energy limit of the resulting amplitudes and compare two types of pomeron coupling to nucleons. PACS numbers: 13.60.Le, 13.75Lb