J. E. Szymanski

Separation of synchronous pitched notes by spectral filtering of harmonics

This paper discusses the separation of two or more simultaneously excited pitched notes from a mono sound file into separate tracks. In fact, this is an intermediate stage in the longer-term goal of separating out at least two interweaving melodies of different sound sources from a mono file. The approach is essentially to filter the set of harmonics of each note from the mixed spectrum in each time frame of audio. A major consideration has been the separation of overlapping harmonics, and three filter designs are proposed for splitting a spectral peak into its constituent partials given the rough frequency and amplitude estimates of each partial contained within. The overall quality of separation has been good for mixes of up to seven orchestral notes and has been confirmed by measured average signal-to-residual ratios of around 10-20 dB

The effect of terrain topography on commonly used resistivity arrays

In this work a study of the effect of surface topographical variations on several dc resistivity arrays is presented. A 2.5-D finite‐element modeling scheme is used to examine the performance of several arrays over buried features that exist below a range of different topographical terrain contexts, such as valleys, hills, and steep slopes. A mesh‐generating algorithm allows a realistic representation of terrain topography. The results confirm that topographical variations can have a significant impact on the field resistivity data values for all resistivity arrays. Further, topographical variations can be treated flexibly using a realistic resistivity forward modeling process. Thus, topographic effects, to the degree they can be modeled, are predictable and should be taken into account when designing surveys and interpreting data.

Square array resistivity anomalies and inhomogeneity ratio calculated by the finite‐element method

In this work the square array configuration is studied. As with any four‐electrode measuring configuration, three different resistances can be measured directly and, in particular, by using the square array these resistance values can be used to obtain a measure of the apparent anisotropy: this is the so‐called azimuthal inhomogeneity ratio (AIR). The AIR is used widely to derive information regarding the directional variation of the subsurface resistivity. Similar types of information can be obtained using any collinear array but would need to be used in a crossed mode. This gives an operational advantage to the square array. Here, the AIR and the square α and β apparent resistivities have been calculated for a number of simple subsurface models. Moreover, the apparent resistivity responses for several different linear arrays were calculated to allow useful comparisons. The forward modeling has been carried out via a 2.5-D finite‐element scheme and an existing approach has been modified in order to calcu...

A reformulation of the LUC CNDO approach to the properties of solids. I. General theory

Hartree-Fock equations are solved for a large unit cell (LUC) periodic system using the linear combination of atomic orbitals (LCAO) approach and within the k=0 semiempirical complete neglect of differential overlap (CNDO) approximation. Convergence difficulties in previous approaches are resolved by careful analysis of the density matrix dependent terms in the Fock matrix. Detailed studies of the density matrices of analytically solvable one-dimensional tight-binding models give insight into the properties of distance-dependent modulating functions that weight certain Coulomb interaction terms. It is shown that the k=0 approximation cannot be fully self-consistent, but it is nevertheless possible to develop satisfactory total energy algorithms that converge rapidly with interaction distance.

Robust eigenstructure assignment with a control design package

Eigenstructure assignment for linear systems is basically an inverse eigenvalue problem. Two possible solutions to this problem that have been implemented on the Ctrl-C commercial design package are presented. One is a least-squares approach, and the other is an iterative method. Both algorithms use singular-value decomposition and produce robust (well-conditioned) answers to the state-feedback pole-assignment problem. An example is included to assess the relative strengths of the two techniques. Both methods give well-conditioned solutions to the problems, and although the iterative design is computationally more expensive, it requires less advance information.<<ETX>>

LUC-LCAO-CNDO calculations on covalent semiconductors

Abstract The complete neglect of differential overlap (CNDO) approach is described within the large unit cell (LUC) formalism and compared with other tight-binding/linear combination of atomic orbitals (LCAO) approaches. The reason for the divergence of some previous calculations of the bulk properties of diamond and silicon is explained, and the application of a modified formalism to calculations on diamond and silicon both in the perfect crystal and in systems of lower symmetry is discussed.

Improved CNDO formalism for bulk properties and surface geometries

Abstract The study of solid surfaces and interfaces is an area of research with many important applications. The objective of this work is to investigate the relaxation and/or reconstruction of the surface of a solid via semiempirical schemes incorporating a total energy algorithm.

Fast Mosaic of High-Resolution Multiple-View Images of Surfaces from Architectural and Heritage Structures

This paper presents an automatic and fast method for creating seamless mosaics from images captured by a special aerial imaging system when imaging architectural and heritage structures. The whole scheme was made following three principles: speediness, robustness and the adaptability to the aerial image acquisition system in our project. We first extract keypoints and match them using the newest SURF algorithm, which can generate large sets of corresponding points fast and robustly. Then, a simple least-squares algorithm can estimate the projective transform parameters. In addition, to increase the robustness, lens distortion correction and global optimization strategy are also adopted. Finally, the aligned set of registered images is processed by an image fusion technique to produce effectively seamless composite images.

Automatic Alignment of Images with Small Overlaps, Sparse Features and Repeated Deceptive Objects

This paper presents an automatic and robust technique for creating seamless mosaics, relying only on a set of input multiple-view images with small overlaps, sparse features and repeated deceptive objects. We first extract keypoints and match them using the SIFT algorithm, which can generate large sets of corresponding keypoints from such images. This establishes a robust basis for a second-stage transform estimation using genetic algorithms and the image fusion algorithm. An adaptive genetic algorithm can escape from local extrema and can potentially realize the global optimum for estimating the projective transform parameters accurately. Finally, the aligned set of registered images is processed by an image fusion technique to produce effectively seamless composite images.

Mosaics of images from architectural and heritage structures

This paper presents an automatic robust system which relies only on the information contained within the original images for the construction of massive composite mosaic images from close-range and high-resolution originals, such as those obtained when imaging architectural and heritage structures. We first apply the Harris Corner Detector to extract a selection of corners and, then, employ both the intensity correlation and the spatial correlation between the corresponding corners for matching them. We estimate the lens distortion parameter and the eight-parameter planar projective transformation matrix via the Levenberg-Marquardt algorithm. After the pairwise registration stage, we used a global optimization strategy, solving a linear system of equations to produce a globally consistent alignment of the entire set of original images. Lastly, image fusion using a weighted blending function together with intensity compensation produces an effective seamless mosaic image. Comparisons with current commercial image-mosaic software are favourable.