An elastoplastic framework for granular materials becoming cohesive through mechanical densification. Part II - the formulation of elastoplastic coupling at large strain

The two key phenomena occurring in the process of ceramic powder compaction are the progressive gain in cohesion and the increase of elastic stiffness, both related to the development of plastic deformation. The latter effect is an example of `elastoplastic coupling', in which the plastic flow affects the elastic properties of the material, and has been so far considered only within the framework of small strain assumption (mainly to describe elastic degradation in rock-like materials), so that it remains completely unexplored for large strain. Therefore, a new finite strain generalization of elastoplastic coupling theory is given to describe the mechanical behaviour of materials evolving from a granular to a dense state. The correct account of elastoplastic coupling and of the specific characteristics of materials evolving from a loose to a dense state (for instance, nonlinear --or linear-- dependence of the elastic part of the deformation on the forming pressure in the granular --or dense-- state) makes the use of existing large strain formulations awkward, if even possible. Therfore, first, we have resorted to a very general setting allowing general transformations between work-conjugate stress and strain measures; second, we have introduced the multiplicative decomposition of the deformation gradient and, third, employing isotropy and hyperelasticity of elastic response, we have obtained a relation between the Biot stress and its `total' and `plastic' work-conjugate strain measure. This is a key result, since it allows an immediate achievement of the rate elastoplastic constitutive equations. Knowing the general form of these equations, all the specific laws governing the behaviour of ceramic powders are finally introduced as generalizations of the small strain counterparts given in Part I of this paper.Comment: 18 pages, 1 figur

Duality-Invariant Gaugino Condensation and One-Loop Corrected Kahler Potentials in String Theory

The duality-invariant gaugino condensation with or without massive matter fields is re-analysed, taking into account the dependence of the string threshold corrections on the moduli fields and recent results concerning one-loop corrected K\"ahler potentials. The scalar potential of the theory for a generic superpotential is also calculated.Comment: 18 page

Evolutionary dynamics and scientific flows of nanotechnology research across geo-economic areas

The purpose of this paper is to analyze, by concentration measures, metrics of dispersion and heterogeneity, the dynamics of the production of scientific output in nanosciences and nanotechnologies across worldwide economic players. The main result is that the concentration ratio of the production of nanotechnology research across different macro subject areas has been reducing over time and space, because knowledge dynamics of nanotechnology research has been spreading among new research fields and different industries. In addition, South Korea and China show higher performance than other countries in nanotechnology scientific products per million people. This scientific analysis is important in order to understand the current knowledge dynamics and technological trajectories in nanotechnology that may support future patterns of economic growth.Nanotechnology; Technological System; Technological Trajectories; Concentration; Changeability, Knowledge Dynamics

Volume 52 - Issue 14 - Monday, January 23, 2016

The Rose Thorn, Rose-Hulman\u27s independent student newspaper.https://scholar.rose-hulman.edu/rosethorn/2155/thumbnail.jp

Global Univalence when Mappings are not Necessarily Continuous

This paper proposes a method of establishing the global univalence of a mapping without theassumption of continuity and the absence of points of inflection. When the functions are notcontinuous and the points of inflections are present, the use of a Jacobian to establish univalencepresents some difficulties. The method of establishing univalency, presented in this paper, in turngeneralizes the theorems on the uniqueness of competitive equilibrium and factor priceequalization