Noise and dissipation on coadjoint orbits

We derive and study stochastic dissipative dynamics on coadjoint orbits by incorporating noise and dissipation into mechanical systems arising from the theory of reduction by symmetry, including a semidirect-product extension. Random attractors are found for this general class of systems when the Lie algebra is semi- simple, provided the top Lyapunov exponent is positive. We study two canonical examples, the free rigid body and the heavy top, whose stochastic integrable reductions are found and numerical simulations of their random attractors are shown

On Intrinsic Magnetic Moments In Black Hole Candidates

In previous work we found that many of the spectral properties of low mass x-ray binaries, including galactic black hole candidates could be explained by a magnetic propeller model that requires an intrinsically magnetized central object. Here we describe how the Einstein field equations of General Relativity and equipartition magnetic fields permit the existence of highly red shifted, extremely long lived, collapsing, radiating objects. We examine the properties of these collapsed objects and discuss characteristics that might lead to their confirmation as the source of black hole candidate phenomena.Comment: 4 pages, emulateapj, accepted for ApJ Letters, October 20, 200

Methods for Calculating the Effective Solar-Optical Properties of a Venetian Blind Layer

© 2005. American Society of Heating, Refrigerating and Air-Conditioning Engineers, Inc. (www.ashrae.org). Published in ASHRAE Transactions, Vol. 111, Part 1. For personal use only. Additional reproduction, distribution, or transmission in either print or digital form is not permitted without ASHRAE’s prior written permission.Window solar gain can strongly influence building energy consumption, peak loads, and comfort. Shading devices are routinely used to control solar gain. The use of venetian blinds is particularly common. There is a strong need for models that can accurately simulate this type of device. As a first step, previous research focused on the mechanisms of longwave radiant exchange. Methods were presented by which spatially averaged optical properties (referred to as “effective” optical properties) can be calculated. An enclosure model was formulated to model the interaction of radiation with the slat surfaces. This optical model allows the venetian blind to be treated as a planar, homogeneous “black-box” layer in a series of glazing layers and, coupled with the appropriate convection model, can be incorporated within a standard one-dimensional center-glass heat transfer analysis. In conjunction with the longwave analysis, the current study deals with the mechanisms of solar radiant exchange. Methods, based on geometric considerations and fundamental radiation analysis, are presented for determining the shading layer’s effective optical properties with respect to the beam component of incident solar radiation—at any angle of incidence. Both specular and diffuse reflection at the slat surfaces is included. The performance of these effective properties is demonstrated and discussed in terms of expected results and compared with other models and experimental results found in the literature.Natural Sciences and Engineering Research Council (Canada

Detection of the spin character of Fe(001) surface states by scanning tunneling microscopy: A theoretical proposal

We consider the magnetic structure on the Fe(001) surface and theoretically study the scanning tunneling spectroscopy using a spin-polarized tip (SP-STM). We show that minority-spin surface states induce a strong bias dependence of the tunneling differential conductance which largely depends on the orientation of the magnetization in the SP-STM tip relative to the easy magnetization axis in the Fe(001) surface. We propose to use this effect in order to determine the spin character of the Fe(001) surface states. This technique can be applied also to other magnetic surfaces in which surface states are observed.Comment: 5 pages, 4 figure

Methods for Calculating the Effective Longwave Radiative Properties of a Venetian Blind Layer

© 2004. American Society of Heating, Refrigerating and Air-Conditioning Engineers, Inc. (www.ashrae.org). Published in ASHRAE Transactions, Vol. 110, Part 1. For personal use only. Additional reproduction, distribution, or transmission in either print or digital form is not permitted without ASHRAE’s prior written permission.Window solar gain can strongly influence building energy consumption, peak loads, and comfort. Shading devices are routinely used to control solar gain. The use of venetian blinds is particularly common. There is a strong need for models that can accurately simulate this type of device. As a first step, this study deals with the mechanisms of longwave radiant exchange. Methods are presented by which spatially averaged optical properties (referred to as “effective” optical proper-ties) can be calculated. An enclosure model was formulated to model the interaction of radiation with the slat surfaces. Six enclosure areas, rather than four, were used to account for the possible overlap of blind slats. This optical model allows the venetian blind to be treated as a planar, homogeneous ''black-box'' layer in a series of glazing layers and, coupled with the appropriate convection model, can be incorporated within a standard one-dimensional center-glass heat transfer analysis. Sample calculations were performed and the resulting effec-tive optical properties discussed. The model compares favor-ably with expected trends and limits. The effect of slat curvature was also examined.Natural Sciences and Engineering Research Counci