Macroscopic Resonant Tunneling in the Presence of Low Frequency Noise

We develop a theory of macroscopic resonant tunneling of flux in a double-well potential in the presence of realistic flux noise with significant low-frequency component. The rate of incoherent flux tunneling between the wells exhibits resonant peaks, the shape and position of which reflect qualitative features of the noise, and can thus serve as a diagnostic tool for studying the low-frequency flux noise in SQUID qubits. We show, in particular, that the noise-induced renormalization of the first resonant peak provides direct information on the temperature of the noise source and the strength of its quantum component.Comment: 4 pages, 1 figur

Mesoscale modelling of polymer aggregate digestion

We use mesoscale simulations to gain insight into the digestion of biopolymers by studying the break-up dynamics of polymer aggregates (boluses) bound by physical cross-links. We investigate aggregate evolution, establishing that the linking bead fraction and the interaction energy are the main parameters controlling stability with respect to diffusion. We show $\textit{via}$ a simplified model that chemical breakdown of the constituent molecules causes aggregates that would otherwise be stable to disperse. We further investigate breakdown of biopolymer aggregates in the presence of fluid flow. Shear flow in the absence of chemical breakdown induces three different regimes depending on the flow Weissenberg number ($Wi$). i) At $Wi \ll 1$, shear flow has a negligible effect on the aggregates. ii) At $Wi \sim 1$, the aggregates behave approximately as solid bodies and move and rotate with the flow. iii) At $Wi \gg 1$, the energy input due to shear overcomes the attractive cross-linking interactions and the boluses are broken up. Finally, we study bolus evolution under the combined action of shear flow and chemical breakdown, demonstrating a synergistic effect between the two at high reaction rates

ON THE DYNAMICS OF COMMERCIAL FISHING AND PARAMETER IDENTIFICATION

This paper has two main objectives. The first is to develop a dynamic model of commercial fisheries different from most existing models that assume optimizing behavior. The industry is assumed to have a well-defined index of performance. Based upon this index, the decision to invest or not is made. We do not, however, assume that the industry or firm is efficient or optimal in its operations. The second is that a new approach of fitting model dynamics to time series data is employed to simultaneously estimate the poorly known initial conditions and parameters of nonlinear fisheries dynamics. The approach is a data assimilation technique known as the variational adjoint method. Estimation of the poorly known initial conditions is one of the attractive features of the variational adjoint method.Resource /Energy Economics and Policy,

Evidence for dielectric aging due to progressive 180 domain wall pinning in polydomain Pb(Zr0.45Ti0.55)O3 thin films

An evidence that the dielectric ageing in the polydomain Pb(Zr0.45Ti0.55)O3 thin films is controlled by progressive pinning of 180 domain walls is presented. To provide such a conclusion, we use a general method, which is based on the study of the time evolution of the nonlinear, but anhysteretic, dielectric response of the ferroelectric to a weak electric field. A thermodynamic model of the ferroelectric system where the dielectric response is controlled by bending movements of pinned 180 domain walls is developed. Within this model, the nonlinear permittivity of the ferroelectric is expressed as a function of the microstructural parameters of the domain pattern. It is shown that using the analysis of the time evolution of the nonlinear permittivity, it is possible to estimate changes in the concentration of the pinning centers that block the movements of the 180 domain walls during aging in polydomain perovskite ferroelectrics.Comment: This version is modifed and corrected according to recently published Erratum: Phys. Rev. B 79, 219903(E) (2009). 21 pages, 3 figure

Quantum Field Theory of Forward Rates with Stochastic Volatility

In a recent formulation of a quantum field theory of forward rates, the volatility of the forward rates was taken to be deterministic. The field theory of the forward rates is generalized to the case of stochastic volatility. Two cases are analyzed, firstly when volatility is taken to be a function of the forward rates, and secondly when volatility is taken to be an independent quantum field. Since volatiltiy is a positive valued quantum field, the full theory turns out to be an interacting nonlinear quantum field theory in two dimensions. The state space and Hamiltonian for the interacting theory are obtained, and shown to have a nontrivial structure due to the manifold moving with a constant velocity. The no arbitrage condition is reformulated in terms of the Hamiltonian of the system, and then exactly solved for the nonlinear interacting case.Comment: 7 Figure

Numerical modeling of dynamic powder compaction using the Kawakita equation of state

Dynamic powder compaction is analyzed using the assumption that the powder behaves, while it is being compacted, like a hydrodynamic fluid in which deviatoric stress and heat conduction effects can be ignored throughout the process. This enables techniques of computational fluid dynamics such the equilibrium flux method to be used as a modeling tool. The equation of state of the powder under compression is assumed to be a modified version of the Kawakita loading curve. Computer simulations using this model are performed for conditions matching as closely as possible with those from experiments by Page and Killen [Powder Metall. 30, 233 (1987)]. The numerical and experimental results are compared and a surprising degree of qualitative agreement is observed

The Potentials of Improving Mineral Source Additional Values in Lampung Province – A Prelimanary Study

oai:ojs2.jesr.eng.unila.ac.id:article/2An initial research on non-metal mineral potential was conducted for stones in Lampung Province. Surveys were conducted to some districts/towns in Lampung to take sample materials. Non-metal mineral chemical composition content analysis of stones was conducted with X-RF method. Lampung had mineral potentials of feldspar, zeolite, kaolin, and basalt of 400,500,000 m3; 18,945,000 m3; 9,750,000 m3; 419,071,833 m3 respectively. These mineral source potentials were distributed in eight districts in Lampung. Processing was required to improve additional values for these mineral sources, including crushing, grinding, classifying, and concentration process. Concentration improvements were required for feldspar and kaolin minerals. Wet high intensity magnetic separator process followed by froth flotation process became solutions to reduce high oxide iron content. Feldspar and kaolin could be used for such industries of ceramic, glass, paper, and refractory. Meanwhile, the zeolite mineral from Lampung could be used for agriculture, plantation, and fishery. Basalt stone would have additional values when this was processed into cast basalt, fiber, and ceramic composite