Discontinuous Edges Research Articles

Scanning electron microscopy in oral cytology.

Sixty-three cell smears from oral mucosa were studied by scanning electron microscopy. Among them, smears from ten healthy controls showed three kinds of cells: flat (superficial) cells with linear anastomosing microridges and microvilli; polygonal (intermediate) cells with well-defined crests between their faces and numerous microvilli; and round (parabasal) cells entirely covered by microvilli. Twenty-five smears from patients with untreated squamous-cell carcinoma showed enlarged polymorphous cells (round, globular, and elongated); microvilli, variable in their dimensions, were irregularly distributed on their surfaces. Eighteen smears from patients with severe epithelial dysplasia showed polymorphous cells with discontinuous but obvious edges separating their faces and with irregular microvilli and ridges. Nine smears were also performed in patients with various other mucosal lesions (lichen planus, leukoplakia, white sponge naevus, pemphigus vulgaris, and herpes). All of these smears were studied comparatively between examination of smears and biopsies by light microscopy. The smears were truly reliable, particularly for distinguishing between dysplastic and tumoral cells.

High-frequency scattering from the edges of impedance discontinuities on a flat plane

A high-frequency solution is presented for the scattering of a plane wave at the edges of surface impedance discontinuities on a fiat ground plane. Arbitrary uniform isotropic boundary conditions and a direction of incidence perpendicular to the edges of the discontinuities are considered for both the transverse electric (TE) and transverse magnetic (TM) cases. An asymptotic approximation of the exact solution given by Maliuzhinets and a spectral extension of the geometrical theory of diffraction (GTD) are used. Uniform expressions for the scattered field received at a point on the surface are given, including surface wave contributions. Numerical results are shown and in some examples they are compared with those obtained from a moment method (MM) solution.

Schematizing spectrograms for speech recognition

An initial step in wide vocabulary, continuous speech recognition is proposed that roughly consists of a schematization of the features seen in conventional spectrograms—e.g., peaks and edges of spectral energy concentrations, temporal discontinuities, and spectral balance information. In a second step, these features can be mapped onto their acoustic‐phonetic correlates—e.g., formant distribution, voice onsets, articulatory closures. A method for locating spectral energy concentrations is given that takes advantage of their usual continuity in time, and thus performs superior to locating peaks in spectral cross sections. It begins with smoothing and flattening convolutions in both the time and frequency dimensions of narrow‐band spectrograms to select the appropriate temporal and spectral scales. Ridges in the resulting two‐dimensional (time‐frequency) surfaces correspond to local spectral energy concentrations. The tops of these ridges are found by the application of a two‐dimensional differential operator at each point in the time‐frequency plane. The operator's definition in terms of the relationship between the gradient and principal directions will be given, along with justification and examples.

On subsonic laminar separation from the discontinuity edge of a profile

Asymptotic methods are used to study a steady subsonic flow of a perfect gas past a convex angle at high Reynolds' numbers. The solution /1/ describing a potential flow past a corner with a free streamline is taken as the limit solution. The pressure gradient in this solution tends to infinity on approaching the corner point from the direction of incoming flow. Its effect on the boundary layer is to form a domain of free interaction, first studied in /2–4/. The Navier-Stokes equations were solved outside the domain of free interaction in the complete neighborhood of the corner in /1/. The flow in the domain of free interaction was studied under the assumption that the surface of the corner is thermally insulated. The problem describing this flow in the first approximation is reduced by means of affine transformations to a problem of laminar separation of an incompressible fluid /5/. This makes it possible to establish a similarity law for subsonic gas flows in the neighborhood of a corner point.

Sufficiency Theorem for Discontinuous Optimal Cost Surfaces

A V type function is introduced for the purpose of modeling the optimal cost surfaces (OCS) of a very general class of optimal control processes, especially state-constrained processes. This classification of the OCS builds from the assumption that the OCS is the countable union of disjoint submanifolds. The V-type function is particularly suitable for handling OCSs that are discontinuous at submanifolds of codimension 1 of the state space. A discontinuous nontransversality condition is presented which keeps trajectories from entering any submanifold of the OCS from a discontinuous edge. A sufficiency theorem utilizing the V-type function is given. This theorem states that if certain conditions are met by a control policy, then it is optimal. The defining of these conditions, together with the sufficiency theorem, provides a classification of the OCS for general optimal control processes with state constraints. An example is provided to demonstrate the implementation of the results.

Detection of Global Edges in Textured Images

Recently geologists have been recognizing the importance of line or edge-like features called lineaments that are commonly detected in Landsat terrain reconnaissance. Lineaments are piecewise discontinuous global lines or edges of low curvature, and they generally have widely varying widths or edge characteristics that make them difficult to detect.

Are the broad continuous absorption features of magnetic peculiar A stars bound-free discontinuities

view Abstract Citations (9) References (41) Co-Reads Similar Papers Volume Content Graphics Metrics Export Citation NASA/ADS Are the broad continuous absorption features of magnetic peculiar A stars bound-free discontinuities? Adelman, S. J. ; Wolken, P. R. Abstract In an attempt to explain the origin of the three well-established broad, continuous absorption features seen in many magnetic peculiar A stars, the locations of bound-free discontinuity edges were calculated for overabundant elements using known energy levels. Although line blending may be important, if bound-free discontinuities contribute to the broad continuous features, then Eu II does to the 4200-A feature while Si I does to the 6300-A feature. No candidate is found for the most commonly seen feature near 5200-A. The formation of these features is discussed in terms of a two zone radially stratified chemically inhomogeneous atmosphere. Publication: The Astrophysical Journal Pub Date: July 1976 DOI: 10.1086/154479 Bibcode: 1976ApJ...207..159A Keywords: A Stars; Energy Levels; Magnetic Stars; Stellar Atmospheres; Stellar Evolution; Stellar Spectra; Absorption Spectra; Abundance; Correlation; Discontinuity; Spectrum Analysis; Tables (Data); Astrophysics full text sources ADS | data products SIMBAD (4)

Semiclassical approximation in a realistic one-body potential

For a system of noninteracting fermions in a one-body potential including spin-orbit interaction, an explicit series in the expansion parameter h ̵ 2 is derived for the “smooth” part of the energy. The formalism is only valid for potentials with no discontinuous edges, and is based on the Wigner-Kirkwood semiclassical partition function. Some numerical calculations are done in realistic spherical and deformed potentials to demonstrate the practical utility of the method. Numerical comparisons with the corresponding Strutinsky calculations are also made.

Design of rectangular reinforced concrete slabs supported on all the sides with a short discontinuous edge

Bending moment coefficients for the design of rectangular reinforced concrete panels supported on four sides with a short discontinuous edge are derived using the strip theory. The moment fields resulting from the use of proposed coefficients are examined in terms of the moment volume for possible savings in reinforcement and compared with other codified procedures. The strip coefficients averaged over the corresponding sides of the panel, besides resulting in considerable savings in reinforcement, are found to be identical with the coefficients predicted by simple yield line theory using an orthotropic layout of reinforcement.

White Line Following For ALV Navigation

A real time processing system and a white line following algorithm used for high speed ALV navigation on structural road are described in this paper. The real time image processing system includes a color video camera, several processors with special functions and a general purpose processing unit based on TMS 320C30 microprocessor. Each special processor performs a standard image processing operation such as image thresholding, color look-up-table, histogram statistics, morphology operation, and so on. A general purpose unit performs some algorithms at high speed. There are two buses in the system. Each processor can communicate with each other through image data bus and communicate with the host computer through extended PC-bus as well. The system is more convenient for programming and can realize vision tasks in real time. There are two steps in the white line following algorithm. The white line starting points are searched by a local threshold and hypothesis-verification method. We enhance the performance of our searching algorithm by three steps: enlarge searching area, use as many features of the white line as possible, feedback line following results to starting point searching for remove illegal starting points. In the window searching scheme, we use multi-directional local projection to find the two gray level discontinuity edges of white line in a window. According to the position orientation and intensity of the two discontinuity edges, we can determine if there is a white line segment in the window. Then we forecast the position of the next window and repeat the steps until the line following is finished according to some rules. We use continuity between two frame images and knowledge of central line of road to guide road region determination when there is one white line in an image. The testing results show that our vision system can detect solid and broken, clean and blurred white lines on the testing field successfully in any weather conditions and at any time of a day. Transactions on Information and Communications Technologies vol 16, © 1996 WIT Press, www.witpress.com, ISSN 1743-3517