Continua with partially constrained microstructure

The mechanical balance equations for a body with microstructure are derived from an expansion of the general Noll’s axiom of frame-indifference that takes into account the behavior of measures of microstructural interactions. Next, we introduce perfect internal constraints and adopt an extended determinism principle to analyze the consequences of their presence. Finally, we define the class of continua with partially constrained microstructure to give a complete dynamical description for a broad family of peculiar materials such as suspensions of rigid rotating granules, pseudo-Cosserat continua and partially constrained micro-spins.

Media Framing of President Muhammadu Buhari’s Human Rights Abuses: a Study of The Punch, Vanguard, The Nation and Daily Trust Newspapers

This study explores how four Nigerian newspapers framed President Muhammadu Buhari’s administration and its human rights campaign. Using newspaper editorials published in The Punch, The Nation, Daily Trust, and Vanguard newspapers of December 2019 as the object of analysis, the paper draws on the methodological context of such framing to investigate how the selected newspapers framed the human rights situation in Nigeria. This study asserts that those newspapers’ editorials used varieties of framing methods, namely: “unrepentant dictator frame”, “resistance frame”, “indifference frame”, “warning frame”, and “sympathetic” frame to portray the government’s disposition to human rights issues. Furthermore, the paper reveals that the Nigerian media is partisan when it comes to the struggle against human rights while their positions on national issues like the fight against human rights abuse are subject to ethnic and political influences, as evident in the Daily Trust editorial. The study also revealed that editorials can be used as essential tools to curtail the excess of government, precisely, to fight against the abuse of human rights. Finally, the paper recommends that newspaper publishers should limit their editorial influences in day-to-day administration of news outlet to engender objectivity, news balance and accuracy in order not to exacerbate the socio-political situation in a multi-ethnic society such as Nigeria.

Investigation on the Use of a Spacetime Formalism for Modeling and Numerical Simulations of Heat Conduction Phenomena

The question of frame-indifference of the thermomechanical models has to be addressed to deal correctly with the behavior of matter undergoing finite transformations. In this work, we propose to test a spacetime formalism to investigate the benefits of the covariance principle for application to covariant modeling and numerical simulations for finite transformations. Several models especially for heat conduction are proposed following this framework and next compared to existing models. This article also investigates numerical simulations using the heat equation with two different thermal dissipative models for heat conduction, without thermomechanical couplings. The numerical comparison between the spacetime thermal models derived in this work and the corresponding Newtonian thermal models, which adds the time as a discretized variable, is also performed through an example to investigate their advantages and drawbacks.

Noll’s Axioms and Formulation of the Closure Relations for the Subgrid Turbulent Tensor in Large Eddy Simulation

In this paper, the relation between the Noll formulation of the principle of material frame indifference and the principle of turbulent frame indifference in large eddy simulation, is revised. The principle of material frame indifference and the principle of turbulent frame indifference proposed by Hutter and Joenk imposes that both constitutive equations and turbulent closure relations must respect both the requirement of form invariance, and the requirement of frame independence. In this paper, a new rule for the formalization of turbulent closure relations, is proposed. The generalized SGS turbulent stress tensor is related exclusively to the generalized SGS turbulent kinetic energy, which is calculated by means of its balance equation, and the modified Leonard tensor.

Rotational invariance conditions in elasticity, gradient elasticity and its connection to isotropy

For homogeneous higher-gradient elasticity models we discuss frame-indifference and isotropy requirements. To this end, we introduce the notions of local versus global SO(3)-invariance and identify frame-indifference (traditionally) with global left SO(3)-invariance and isotropy with global right SO(3)-invariance. For specific restricted representations, the energy may also be local left SO(3)-invariant as well as local right SO(3)-invariant. Then we turn to linear models and consider a consequence of frame-indifference together with isotropy in nonlinear elasticity and apply this joint invariance condition to some specific linear models. The interesting point is the appearance of finite rotations in transformations of a geometrically linear model. It is shown that when starting with a linear model defined already in the infinitesimal symmetric strain [Formula: see text], the new invariance condition is equivalent to the isotropy of the linear formulation. Therefore, it may also be used in higher-gradient elasticity models for a simple check of isotropy and for extensions to anisotropy. In this respect we consider in more detail variational formulations of the linear indeterminate couple-stress model, a new variant of it with symmetric force stresses and general linear gradient elasticity.