9,186 research outputs found
Local Author Book Talk: Meet D.M. Pulley author of The Dead Key
No full textLocal Author D.M. Pulley, author of The Dead Key.
2014 Winner — Amazon Breakthrough Novel Award — Grand Prize and Mystery & Thriller Fiction Winner. It’s 1998, and for years the old First Bank of Cleveland has sat abandoned, perfectly preserved, its secrets only speculated on by the outside world.--Source Amazon.com
These books and all Friends of the Library 2021/2022 book selections are on sale at Viking Outfitters, located in the CSU Student Center
Canceled: Local Author Book Talk: Meet D.M. Pulley author of The Dead Key
No full textThis event has been canceled due to the Coronavirus.
Meet Local Author D.M. Pulley, author of The Dead Key.
2014 Winner — Amazon Breakthrough Novel Award — Grand Prize and Mystery & Thriller Fiction Winner. It’s 1998, and for years the old First Bank of Cleveland has sat abandoned, perfectly preserved, its secrets only speculated on by the outside world.--Source Amazon.com
The books titled The Dead Key, No one’s Home, Unclaimed Victim, and The Buried Book will be available for sale by Viking Outfitters at the event. These books and all Friends of the Library 2019/2020 book selections are on sale at Viking Outfitters, located in the CSU Student Center
Analysis and design of a two-speed single-phase induction motor with 2 and 18 pole special windings
No full textThe motor presented employs multiple independent windings for operation with two very different pole numbers. The 18-pole field is produced with a symmetrical three-phase winding connected in a Steinmetz arrangement to a single-phase supply. A unified analysis method has been developed and used to demonstrate the equivalence of a Steinmetz delta or star connection with a main and auxiliary winding of a single-phase motor. The method has been experimentally validated and also included are some specific motor design considerations
A phase-field model with convection: sharp-interface asymptotics
No full textWe have previously developed a phase-field model of solidification that includes convection in the melt [Physica D 135 (2000) 175]. This model represents the two phases as viscous liquids, where the putative solid phase has a viscosity much larger than the liquid phase. The object of this paper is to examine in detail a simplified version of the governing equations for this phase-field model in the sharp-interface limit to derive the interfacial conditions of the associated free-boundary problem. The importance of this analysis is that it reveals the underlying physical mechanisms built into the phase-field model in the context of a free-boundary problem and, in turn, provides a further validation of the model. In equilibrium, we recover the standard interfacial conditions including the Young–Laplace and Clausius–Clapeyron equations that relate the temperature to the pressures in the two bulk phases, the interface curvature and material parameters. In nonequilibrium, we identify boundary conditions associated with classical hydrodynamics, such as the normal mass flux condition, the no-slip condition and stress balances. We also identify the heat flux balance condition which is modified to account for the flow, interface curvature and density difference between the bulk phases. The interface temperature satisfies a nonequilibrium version of the Clausius–Clapeyron relation which includes the effects of curvature, attachment kinetics and viscous dissipation
A phase-field model of solidification with convection
No full textWe develop a phase-field model for the solidification of a pure material that includes convection in the liquid phase. The model permits the interface to have an anisotropic surface energy, and allows a quasi-incompressible thermodynamic description in which the densities in the solid and liquid phases may each be uniform. The solid phase is modeled as an extremely viscous liquid, and the formalism of irreversible thermodynamics is employed to derive the governing equations. We investigate the behavior of our model in two important simple situations corresponding to the solidification of a planar interface at constant velocity: density change flow and a shear flow. In the former case we obtain a non-equilibrium form of the Clausius–Clapeyron equation and investigate its behavior by both a direct numerical integration of the governing equations, and an asymptotic analysis corresponding to a small density difference between the two phases. In the case of a parallel shear flow we are able to obtain an exact solution which allows us to investigate its behavior in the sharp interface limit, and for large values of the viscosity ratio
A phase-field/fluid motion model of solidification: Investigation of flow effects during directional solidification and dendritic growth
No full textThe phase-field model of solidification is extended to include the effects of fluid flow in the melt. The phase-field model is based on coupling the nist-equations for heat flow in the liquid and solid phases with an auxiliary nist-equation that describes the evolution of the phase-field variable, which is a non-conserved order parameter indicating the local phase, solid or liquid, at each point of the material. The solid-liquid interface is then represented by a diffuse transition layer in which the phase-field variable changes rapidly between its values in the bulk phases. The model is extended to include fluid flow by a further coupling to the Navier-Stokes nist-equations. Preliminary studies have been performed for a model in which the solid phase is treated as a liquid of high viscosity compared to the liquid phase. The main coupling in the Navier-Stokes nist-equations is then through an additional term in the stress tensor that depends on the gradients of the phase-field variable, representing the effects of capillary forces within the diffuse interface
Thin interface asymptotics for an energy/entropy approach to phase-field models with unequal conductivities
No full textKarma and Rappel [Phys. Rev. E 57 (1998) 4342] recently developed a new sharp interface asymptotic analysis of the phase-field equations that is especially appropriate for modeling dendritic growth at low undercoolings. Their approach relieves a stringent restriction on the interface thickness that applies in the conventional asymptotic analysis, and has the added advantage that interfacial kinetic effects can also be eliminated. However, their analysis focussed on the case of equal thermal conductivities in the solid and liquid phases; when applied to a standard phase-field model with unequal conductivities, anomalous terms arise in the limiting forms of the boundary conditions for the interfacial temperature that are not present in conventional sharp interface solidification models, as discussed further by Almgren [SIAM J. Appl. Math. 59 (1999) 2086]. In this paper we apply their asymptotic methodology to a generalized phase-field model which is derived using a thermodynamically consistent approach that is based on independent entropy and internal energy gradient functionals that include double wells in both the entropy and internal energy densities. The additional degrees of freedom associated with the generalized phase-field equations can be used to eliminate the anomalous terms that arise for unequal conductivities
Second order phase field asymptotics for multi-component systems
No full textAn asymptotic analysis of a phase field model for solidification in multicomponent
alloy systems is presented. In the limit of vanishing interface thickness the
related sharp interface model is approximated to second order by taking a non-constant
kinetic correction term into account. In numerical experiments the approximation properties
of the phase field model as well as the gain in computational effort due to the
correction are investigated
Signal reconstruction from the magnitude and phase of a generalised wavelet transform
No full textThis paper presents a generalisation of the traditional Wavelet Transform (WT) called the Generalised Wavelet Transform (GWT). This generalisation incorporates a number of linear Time-Frequency Representations (TFRs), including the Short-Time Fourier Transform (ST-FT) and WT. This paper addresses the problem of signal reconstruction from an arbitrary GWT. In order to be robust to modifications of the TFR, a Minimum Least Squares (MLS) approach to signal reconstruction is presented. This results in a method for reconstructing a MLS signal from a modified or altered GWT
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