[en] The Combustion Corridor is a concept in which researchers in combustion and thermal sciences have unimpeded access to large volumes of remote computational results. This will enable remote, collaborative analysis and visualization of state-of-the-art combustion science results. The Engine Research Center (ERC) at the University of Wisconsin - Madison partnered with Lawrence Berkeley National Laboratory, Argonne National Laboratory, Sandia National Laboratory, and several other universities to build and test the first stages of a combustion corridor. The ERC served two important functions in this partnership. First, we work extensively with combustion simulations so we were able to provide real world research data sets for testing the Corridor concepts. Second, the ERC was part of an extension of the high bandwidth based DOE National Laboratory connections to universities

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[en] An algorithm due to Loud is used to find asymptotically convergent series solutions for limit cycles subjected to weak periodic perturbations. If an exact or approximate solution to the unperturbed limit cycle is available near or far from marginal stability, then accurate predictions can be made for entrainment bands and the phase relationships between the various oscillatory chemical species and the perturbation. The utility of this method is shown for several model systems. In an appendix, the appearance and character of critical slowing down at the edges of entrainment bands is demonstrated

[en] A mathematical model has been proposed for an isotopic exchange reaction between the solid particles and ions in a solution of finite volume. A theoretical equation has been derived to predict the exchange fraction as a function of the dimensionless time T with the kinetic parameters xi, xi₁ and final fractional uptake U as parameters for the exchange rate controlled by combined film diffusion, surface chemical reaction and intraparticle diffusion. The exchange fraction increases as the values of T, U, xi and xi₁ increase. Experimental results of the isotopic exchange systems CaCO₃(s)Ca²⁺ (aq), CaC₂O₄(s)/Ca²⁺ (aq) and Ca-form Dowex 50W-X8/Ca²⁺ (aq) agree well with the theoretical equation proposed in this study. (author)

[en] An aggregation growth model of three species A, B and C with the competition between catalyzed birth and catalyzed death is proposed. Irreversible aggregation occurs between any two aggregates of the like species with the constant rate kernels I_n(n = 1,2,3). Meanwhile, a monomer birth of an A species aggregate of size k occurs under the catalysis of a B species aggregate of size j with the catalyzed birth rate kernel K(k,j) = Kkj^v and a monomer death of an A species aggregate of size k occurs under the catalysis of a C species aggregate of size j with the catalyzed death rate kernel L(k,j)=Lkj^v, where v is a parameter reflecting the dependence of the catalysis reaction rates of birth and death on the size of catalyst aggregate. The kinetic evolution behaviours of the three species are investigated by the rate equation approach based on the mean-field theory. The form of the aggregate size distribution of A species a_k(t) is found to be dependent crucially on the competition between the catalyzed birth and death of A species, as well as the irreversible aggregation processes of the three species: (1) In the v < 0 case, the irreversible aggregation dominates the process, and a_k(t) satisfies the conventional scaling form; (2) In the v ≥ 0 case, the competition between the catalyzed birth and death dominates the process. When the catalyzed birth controls the process, a_k(t) takes the conventional or generalized scaling form. While the catalyzed death controls the process, the scaling description of the aggregate size distribution breaks down completely

[en] Positronium (Ps) reaction rates (κ) with weak Acceptors (Ac) leading to the formation of Ps-Ac complexes show several intriguing features: non-monotonic temperature dependence of κ (departing from the usual Arrhenius paradigm), considerable variability of κ with respect to different solvents, and anomalies in response to external pressure at ambient temperature (large changes of κ in some media and hardly any in others). We explain all these phenomena, introducing the novel concept of a critical surface tension, which unifies observations in diverse non-polar solvents at different temperatures and pressures

[en] A highly simple and effective new methodology has been proposed to analyze the reaction kinetics of non-equilibrium mass transport. Interphase mass transfer in an evidently non-ideal liquid system has been described as trajectories on a reaction plane by introducing a logarithmic driving force L_G which equals to A⁺/RT, where A⁺ is newly defined chemical affinity of a solute. The affinity A⁺ is referenced not only to the reaction state but to the equilibrium state, and is different from the De Donder's affinity defined solely by a reaction state. The affinity A⁺ is always smaller than the conventional one. It has also been concluded that extractive transfer might occur in a region A⁺>0. This description of transfer phenomena enables us to treat the reactions directly without the knowledge of rigorous activities of solutes, and is independent to the selection of concentration scale as well as the reference systems for chemical potentials. The affinity A⁺, i.e. the upper limit of the reaction trajectories, and the rate of the decrease in the logarithmic driving force have been represented by A⁺ ≅ -RTlnξ and -dL_G/dξ=1/ξ using the degree of advancement ξ. Consequently, the thermodynamic analysis of reaction trajectories gave insights about the reaction kinetics and its characteristics for two phase systems containing multi-solutes. (author)

[en] In the first part, some definitions and the thermodynamic and kinetic isotopic effect concepts are recalled. In the second part the kinetic laws are established, in homogeneous and heterogeneous medium (one component being on occasions present in both phases), without and with isotopic effects. Emphasis is put on application to separation of isotopes, the separation factor α being close to 1, one isotope being in large excess with respect to the other one. Isotopic transfer is then given by: J = Ka (x - y/α) where x and y are the (isotopic) mole fractions in both phases, Ka may be either the rate of exchange or a transfer coefficient which can be considered as the 'same in both ways' if α-1 is small compared to the relative error on the measure of Ka. The third part is devoted to isotopic exchange reactors. Relationships between their efficiency and kinetics are established in some simple cases: plug cocurrent flow reactors, perfectly mixed reactors, countercurrent reactors without axial mixing. We treat only cases where α and the up flow to down flow ratio is close to 1 so that Murphee efficiency approximately overall efficiency (discrete stage contactors). HTU (phase 1) approximately HTU (phase 2) approximately HETP (columns). In a fourth part, an expression of the isotopic separative power of reactors is proposed and discussed

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No abstract available