The design of multiconfiguration axisymmetric optical systems

Imperial Users onl

Diversifying two-stage mixing approach (TSMA) for recycled aggregate concrete: TSMAs and TSMAsc

Griffith Sciences, Griffith School of EngineeringFull Tex

The probability density function of a hardware performance parameter

Probability density function of hardware performance parameter and incentive contractin

Analytical developments for definition and prediction of USB noise

A systematic acoustic data base and associated flow data are used in identifying the noise generating mechanisms of upper surface blown flap configurations of short takeoff and landing aircraft. Theory is developed for the radiated sound field of the highly sheared flow of the trailing edge wake. An empirical method is also developed using extensive experimental data and physical reasonings to predict the noise levels

Study of off-diagonal disorder using the typical medium dynamical cluster approximation

We generalize the typical medium dynamical cluster approximation (TMDCA) and the local Blackman, Esterling, and Berk (BEB) method for systems with off-diagonal disorder. Using our extended formalism we perform a systematic study of the effects of non-local disorder-induced correlations and of off-diagonal disorder on the density of states and the mobility edge of the Anderson localized states. We apply our method to the three-dimensional Anderson model with configuration dependent hopping and find fast convergence with modest cluster sizes. Our results are in good agreement with the data obtained using exact diagonalization, and the transfer matrix and kernel polynomial methods.Comment: 10 pages, 8 figure

The Application of Convex Hull in Industrial X-Ray Computerized Tomography

In some x-ray CT situations, the x-ray data of the object are available only in a limited angular range. Limited-angle imaging occurs, for example, when scanning in an angular range is obstructed by other physical objects, or when the x-ray is attenuated too much in a particular angular range to serve any useful purpose. These situations are illustrated in Fig. 1. Under such circumstances limited-angle image reconstruction techniques could be employed to reconstruct the object from the x-ray data and other information about the object, such as (1) exterior boundary of the object; (2) upper bound of the object density; (3) lower bound of the object density. It has been shown that by using this information in addition to the limited-angle x-ray data, the object can be reconstructed uniquely [1]. The limited-angle reconstruction algorithm developed in the above reference is shown in Fig. 2; the image is transformed back and forth between the object space by filtered backprojection, and the projection space by projection, with corrections by the a priori information in the object space and the limited-angle known projections in the projection space

3-Dimensional Flaw Characterization Through 2-Dimensional Image Reconstructions

The 3-dimensional Born approximation is a powerful method for characterizing flaws because it can be applied to characterize flaws of any shape. Yet, the method has a number of difficulties, such as taking and processing a large amount of data, and the complications associated with 3-dimensional image reconstructions such as 3-dimensional interpolation, long computing time, etc. For these reasons the method is usually simplified and restricted to characterize symmetrically shaped flaws, which can be characterized by using only a small number of pulse echoes. Though this procedure is simple, it cannot be applied to characterize flaws of more general shape