Modelling and control of natural convection in canned foods

In this paper we study mathematically an industrial problemrelated to sterilization processes involving heat transfer bynatural convection. We give results of existence and regularityfor the solution of this problem. We recast the whole problemas an optimal control problem with pointwise constraints onthe state and the control in order to ensure the reduction ofmicroorganism concentration and the retention of nutrients,and to save energy. Finally, we give results on existence ofthe optimal solution and optimality conditions for its characterization.     

On some nonself mappings

Let X be a Banach space, let K be a non–empty closed subset of X and let T : K → X be a non–self mapping. The main result of this paper is that if T satisfies the contractive–type condition (1.1) below and maps ?K (?K the boundary of K) into K then T has a unique fixed point in K.     

Why consumers behave as they do with respect to food safety and risk information

In recent years, it seems that consumers are generally uncertain about the safety and quality of their food and their risk perception differs substantially from that of experts. Hormone and veterinary drug residues in meat persist to occupy a high position in European consumers' food concern rankings. The aim of this contribution is to provide a better understanding to food risk analysts of why consumers behave as they do with respect to food safety and risk information. This paper presents some cases of seemingly irrational and inconsistent consumer behaviour with respect to food safety and risk information and provides explanations for these behaviours based on the nature of the risk and individual psychological processes. Potential solutions for rebuilding consumer confidence in food safety and bridging between lay and expert opinions towards food risks are reviewed. These include traceability and labelling, segmented communication approaches and public involvement in risk management decision-making.     

Awareness on adverse effects of nanotechnology increases negative perception among public: survey study from Singapore

As has been demonstrated by recent societal controversies associated with the introduction of novel technologies, societal acceptance of a technology and its applications is shaped by consumers’ perceived risks and benefits. The research reported here investigates public perceptions of nanotechnology in Singapore, where technological innovation is an established part of the economy, and it might be expected that consumer perceptions of risk are low, and those of benefit are high. The contribution of socio-demographic variables, knowledge level and exposure to risk information in shaping risk perception about nanotechnology applications within different application sectors were analysed. About ~80 % of respondents have some understanding of nanotechnology, 60 % report having heard some negative information, and 39 % perceive nanotechnology as beneficial, while 27.5 % perceive it as risky. Nanotechnology application in food was reported to cause the most concern in the consumers included in the sample. Two-step cluster analysis of the data enabled grouping of respondents into those who expressed ‘less concern’ or ‘more concern’ based on their average scores for concern levels expressed with applications of nanotechnology in different sectors. Profiling of these clusters revealed that, apart from various socio-demographic factors, exposure to risk-related information, rather than awareness in nanotechnology itself, resulted in respondents expressing greater concern about nanotechnology applications. The results provide evidence upon which regulatory agencies and industries can base policies regarding informed risk–benefit communication and management associated with the introduction of commercial applications of nanotechnology.     

The Dual Stream Function Representation of an Ideal Steady Fluid Flow and its Local Geometric Structure

Using the methodology of Lie groups and Lie algebras we determine new symmetry and equivalence classes of the stationary three-dimensional Euler equations by introducing potential functions that are based on the so-called dual stream function representation of the steady state velocity field u(x, y, z) = ?λ(x, y, z) × ?μ(x, y, z), which itself can only be defined locally. In particular an infinite dimensional Lie algebra for Beltrami fields is gained. We show that this Lie algebra generates canonical transformations of a Hamiltonian flow for the dual pair of variables \(\lambda \) and \(\mu \) . It enables us to make the classification of a two-dimensional Riemannian manifold \(M^{2}\) wherein \((\lambda ,\mu )\) presents the local coordinates of \(M^{2}\) . Furthermore the local geometry of this manifold is explored in detail. As a result an infinite set of locally conserved currents and charges in the context of a conformal field theory is finally observed.     

Proposal for an Invariant Nonlinear Eddy Viscosity Model based on a Consistent 4D Turbulence Modelling Approach

The aim of this new approach is to demonstrate that modelling on a 3D spatial manifold is not equivalent to modelling on a true 4D space-time manifold within Newtonian physics. In the framework of turbulence modelling it will be shown that by geometrically reformulating the averaged Navier-Stokes equations on a 4D non-Riemannian manifold without changing the physical content of the theory, additional modelling restrictions will naturally emerge which are absent in the usual Euclidean (3 + 1)D formulation. By proposing a non-linear eddy viscosity model within the k − ϵ family for high turbulent Reynolds numbers the new invariant modelling approach will demonstrate its clear superiority over current (3 + 1)D modelling techniques. (© 2009 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim)