Numerical analysis of microwave assisted thermocatalytic decomposition of methane

assisted thermocatalytic decomposition of methane with activated carbon as the catalyst. A simple reaction kinetic model for methane conversion (accounting for catalyst deactivation)is developed from previously published experimental data and coupled with the governing equations for the microwaves, heat transfer, mass transfer and fluid flow physics. Temperature distribution and concentration profiles of CH4 & H2 in the catalyst bed are presented. The temperature profiles at different input power values predict a nonuniform temperature distribution with hot-spots near the top and bottom of the catalyst. The concentration profiles predict a linear variation of CH4 and H2 concentration along the length of the reactor and show a good agreement with experimental conversion values. The influence of volumetric hourly space velocity on methane conversion is also investigated

Nikishin systems are perfect

K. Mahler introduced the concept of perfect systems in the general theory he developed for the simultaneous Hermite-Pade approximation of analytic functions. We prove that Nikishin systems are perfect providing, by far, the largest class of systems of functions for which this important property holds. As consequences, in the context of Nikishin systems, we obtain: an extension of Markov's theorem to simultaneous Hermite-Pade approximation, a general result on the convergence of simultaneous quadrature rules of Gauss-Jacobi type, the logarithmic asymptotics of general sequences of multiple orthogonal polynomials, and an extension of the Denisov-Rakhmanov theorem for the ratio asymptotics of mixed type multiple orthogonal polynomials.Comment: 39 page

A real options approach to tender offers and acquisitions processes

Corporate control has added value for an investor since it gives degrees of freedom about the use of assets, sources of finance, salaries, etc. On the other hand, real options create value through the flexibility associated to the ability to react to some relevant uncertainty. The process of acquisition of corporate control can have two real options associated, a waiting option and a growth option. In the waiting option value is created through sequential investment instead of investing at once, while the growth option carries all the private benefits the investor can seize from control by making follow up investments, which can also justify premiums paid above the former market price. A relevant proposition of our paper is that the exercise price of the growth option (and hence the amount to be paid as the control premium) can be affected by the release of information. We develop a model for these two theoretical extremes, one where the exercise price fully reacts to events, and one where the exercise price does not react at all, and we obtain that the timing of the process of acquiring control would depend on the reaction of the price to be paid to obtain control, so would the size of the control premium over the former price.

Numerical investigation of microwave-assisted pyrolysis of lignin

A comprehensive three-dimensional mathematical model is developed for studying the microwave-assisted pyrolysis of biomass. Kraft Lignin is considered as biomass feedstock in the model, and a mixture of lignin and char, is used as the sample for pyrolysis. A lumped kinetic model which considers three lumped pyrolysis products (gas, liquid and remaining solid fractions) is coupled with the governing equations for the microwave field, heat transfer, mass transfer, Darcy fluid flow and a transient numerical analysis is performed. The distribution of electric field in the microwave cavity, and the distribution of electric field, temperature, and pyrolysis products within the lignin sample are presented. The lignin sample is predicted to undergo volumetric heating when subjected to microwave heating. Accordingly the reaction zone extends from the center of the biomass sample bed towards the outer surface. Preliminary evaluation of the applicability of the model for assessing the effect of different parameters on the microwave pyrolysis of lignin is also carried out