Dielectric behavior of beef meat in the 1-1500kHz range: Simulation with the Fricke/Cole-Cole model

The electrical properties of biological tissues have been researched for many years. Impedance measurements observed with increasing frequencies are mainly attributed to changes in membrane conductivity and ion and charged-molecule mobility (mainly Na⁺, K⁺, CL⁻ ions). Equivalent circuits with passive electrical components are frequently used as a support model for presentation and analyses of the behavior of tissues submitted to electrical fields. Fricke proposed an electrical model where the elements are resistive and capacitive. The model is composed of a resistive element (Rp) representing extracellular fluids (ECF) placed in parallel with a capacitive element (Cs) representing insulating membranes in series and a resistive element (Rs) representing intracellular fluids (ICF). This model is able to describe impedance measurements: at lower frequencies, most of the current flows around the cells without being able to penetrate them, while at higher frequencies the membranes lose their insulating properties and the current flows through both the extracellular and intracellular compartments. Since meat ageing induces structural change, particularly in membrane integrity, the insulating properties of membranes decrease, and intracellular and extracellular electrolytes mix, thus driving changes in their electrical properties. We report a method combining the Fricke and Cole–Cole models that was developed to monitor and explain tissues conductivity changes in preferential directions during beef meat ageing.     

World Bank: catalyst for Third World urban development

The World Bank finances projects involving urban development, water supply, sanitation and transportation. These projects are implemented in rural as well as in urban areas, and one can roughly say that the weight which the Bank has given to the rural world is at least comparable to that given to cities and towns. This reflects the importance of the rural population and economy in most developing countries, where commonly rural population and agricultural productivity represent some 70% of the total population and total value added of the country.     

Transferts thermiques entre un serpentin et des fluides newtoniens ou non—newtoniens agités par une turbine à pales inclinées dans une cuve

The present work deals with the heat transfer from a hélicoïdal worm to newtonian or non-newtonian liquids, which and stirred by a 4 pitched blade-turbine in a cylindrical tank. The effective viscosity of the pseudoplastic liquids is determined by the Metzner-Otto model combined with the Ellis rheological equation. The heat transfer in the newtonian fluids in a turbulent system is most precisely represented by the following equations: (a) (b) In the case of non-newtonian fluids and of downward pumping, the following equation enables to obtain a very precise evaluation of the heat-transfer coefficient in a transitional flow.      

An explicit formulation for an efficient triangular plate-bending element

In this paper a new explicit expression of the stiffness matrix of the 9 degrees-of-freedom plate-bending triangular element called DKT in Reference 1 is presented. Some additional interesting numerical results assessing the behaviour of this element are presented and discussed.