1,087 Matching Results

Search Results

Advanced search parameters have been applied.

in subjects: "Image Processing"

open access

Validation and sensitivity of a simulated photograph technique for visibility modeling

The Los Alamos Scientific Laboratory (LASL) visibility model is capable of producing simulated before and after pictures that illustrate visual effects of smoke plumes. Although the model has been under development for a few years, until recently there had been very little testing of the model against field experience or testing of sensitivity of the model results to numerical approximations used in the model. Further validation and sensitivity testing of the LASL model began in late 1979. The … more

Date: January 1, 1980

Creator: Williams, M.; Chan, L.Y. & Lewis, R.

Item Type: Article

Partner: UNT Libraries Government Documents Department

open access

Detection sensitivity of x-ray CT imaging for NDE of green-state ceramics

Improved ceramic-processing methods that use pressure slip-casting and injection molding are being developed at Norton Advanced Ceramics, with a goal of producing reliable structural ceramics for advanced heat engines. Nondestructive evaluation (NDE) of ceramic parts at different stages of processing can provide useful diagnostic information to help improve processing techniques. For example, an evaluation of density gradients in as-cast green-body samples can be used to judge mold performance … more

Date: 1991~

Creator: Gopalsami, N.; Rizo, P.; Ellingson, W. A. & Tracey, D. M.

Item Type: Article

Partner: UNT Libraries Government Documents Department

open access

Advances in Diagnostic Instrumentation

Developments in medical imaging in the last ten years are described. Techniques include fine focus x-ray tubes, computerized tomography, emission tomography, and ultrasonography. (ACR)

Date: January 1, 1980

Creator: Perez-Mendez, V.

Item Type: Report

Partner: UNT Libraries Government Documents Department

open access

Electron beam and high-speed optical diagnostics for the Los Alamos HIBAF (High Brightness Accelerator FEL) Facility

Characterization of the electron beam's properties will be a major task after the upgrade of the Los Alamos Free-Electron Laser (FEL) Facility with a photoelectric injector (PEI) and increased acceleration capability to 40 MeV. Adjustments to the previous diagnostics package that address the lower beam emittance, higher energy, and wakefield source reduction issues will be discussed. 6 refs., 8 figs., 1 tab.

Date: January 1, 1989

Creator: Lumpkin, A. H.; Cornelius, W. D.; Stein, W. E.; Feldman, R. B.; Meier, K. L. & Young, L. M.

Item Type: Article

Partner: UNT Libraries Government Documents Department

open access

MLE (Maximum Likelihood Estimator) reconstruction of a brain phantom using a Monte Carlo transition matrix and a statistical stopping rule

In order to study properties of the Maximum Likelihood Estimator (MLE) algorithm for image reconstruction in Positron Emission Tomographyy (PET), the algorithm is applied to data obtained by the ECAT-III tomograph from a brain phantom. The procedure for subtracting accidental coincidences from the data stream generated by this physical phantom is such that he resultant data are not Poisson distributed. This makes the present investigation different from other investigations based on computer-si… more

Date: October 1, 1987

Creator: Veklerov, E.; Llacer, J. & Hoffman, E.J.

Item Type: Article

Partner: UNT Libraries Government Documents Department

open access

Considerations for imaging system implementation in a networked environment

Information storage and retrieval systems that utilize raster images are increasing in popularity on a wide variety of platforms. Image systems typically involve the transmission of data files in the 100 KiloByte to 1 MegaByte range to users on specialized workstations who expect retrieval in a matter of seconds. The results of the pilot study outlines the potential for the sharing of image information among various platforms and systems, and sets expectations regarding the level of integration. more

Date: January 1, 1991

Creator: Hudson, B.J.

Item Type: Article

Partner: UNT Libraries Government Documents Department

open access

General-purpose adaptive edge detector based on an empirical edge model

We present a new approach to computer edge detection for image mensuration. Our technique uses data from the actual image to build an edge-detector template for a matched filtering algorithm. We show that the procedure is superior to classical, template matching techniques for a computer-generated image and for a very noisy x-ray image.

Date: January 1, 1982

Creator: Breedlove, J.R. Jr. & Cantoni, V.

Item Type: Article

Partner: UNT Libraries Government Documents Department

open access

The Soviet applied information sciences in a time of change

The Foreign Applied Sciences Assessment Center (FASAC) conducts reviews of selected areas of foreign basic and applied science by US scientists who are technically expert and active in the fields reviewed. Several of the FASAC assessments of Soviet science have involved various aspects of the information sciences, including enabling technologies and applications, as well as the core information sciences. This report draws upon those FASAC assessment reports, the expert judgment of some of the a… more

Date: July 1, 1991

Creator: Bengston, J.; Cronin, R. R. & Davidson, R. B.

Item Type: Report

Partner: UNT Libraries Government Documents Department

open access

CT reconstruction from limited projection angles

When the available CT projection data are incomplete, there exists a null space in the space of possible reconstructions about which the data provide no information. Deterministic CT reconstructions are impotent in regard to this null space. Furthermore, it is shown that consistency conditions based on projection moments do not provide the missing projections. When the projection data consist of a set of parallel projections that do not encompass a complete 180/sup 0/ rotation, the null space c… more

Date: January 1, 1982

Creator: Hanson, K. M.

Item Type: Article

Partner: UNT Libraries Government Documents Department

open access

Examples of maximum likelihood spatial filtering

A maximum-likelihood method for estimating spatial frequency components of truncated sections of data is described. The method is used to estimate the one-dimensional Fourier transform of short scans of images of an edge and of a slit. With the aid of a constrained least-squares noise control, the frequency response of the imaging system is computed from the estimated Fourier transform.

Date: January 1, 1977

Creator: Lahart, M.J.

Item Type: Article

Partner: UNT Libraries Government Documents Department

open access

Overview of image reconstruction

Image reconstruction (or computerized tomography, etc.) is any process whereby a function, f, on R/sup n/ is estimated from empirical data pertaining to its integrals, ..integral..f(x) dx, for some collection of hyperplanes of dimension k < n. The paper begins with background information on how image reconstruction problems have arisen in practice, and describes some of the application areas of past or current interest; these include radioastronomy, optics, radiology and nuclear medicine, elect… more

Date: April 1, 1980

Creator: Marr, R.B.

Item Type: Article

Partner: UNT Libraries Government Documents Department

open access

Phase distribution measurements in narrow rectangular channels using image-processing techniques

Phase distribution of air-water flow in a narrow rectangular channel is examined using image-processing techniques. Ink is added to the water, and clear channel walls were used to allow high-speed, still photographs and video tape to be taken of the air-water flow field. Flow field images are digitized and stored in a Macintosh IIci computer using a frame grabber board. Local grey levels are related to liquid thickness in the flow channel using a calibration fixture. Image-processing shareware … more

Date: June 1, 1992

Creator: Bentley, C. L. & Ruggles, A. E.

Item Type: Report

Partner: UNT Libraries Government Documents Department

open access

Rationale of the ratio image in multispectral remote sensing

A simple mathematical interpretation of the properties of ratio images derived from LANDSAT and other sources of multispectral imagery is presented. A spectral signature is defined which is well represented by ratios of pairs of spectral bands and can be related to the problem of clustering and unsupervised learning. Some practical problems arising in the generation of LANDSAT ratio images are considered, and an effective, simple method for reduction of the dynamic range of such images is prese… more

Date: January 1, 1977

Creator: Wecksung, G.W. & Breedlove, J.R. Jr.

Item Type: Article

Partner: UNT Libraries Government Documents Department

open access

Survey of thermal imaging technology and applications at the Savannah River Site

This memorandum is an introduction to thermal imaging systems and their use. Emission of infrared radiation from ideal and real materials is described, as are methods of detection in modern thermal imaging systems. Typical specifications and features of commercially available thermal imaging systems are described, and uses of thermal imaging are discussed. At the Savannah River Site (SRS), thermal imaging has been used extensively to measure the temperature of surface water that carries heat fr… more

Date: October 9, 1989

Item Type: Report

Partner: UNT Libraries Government Documents Department

open access

Application of digital image analysis techniques to the Geyser's data and topography

This paper describes the results of digital image analysis and techniques applied to acoustic sounder data and topographic relief in the Geyser's region. The two dimensional fast Fourier transform (2DFFT) represents the spacial variability of a photographic image. The spacial variability of topography in complex terrain can be represented in this way and insight into degree of complexity and dominating spacial wavelengths can be gained. This was performed for a 16 km square digitized topographi… more

Date: May 5, 1980

Creator: Porch, W.M.

Item Type: Article

Partner: UNT Libraries Government Documents Department

open access

X-ray holographic microscopy experiments at the Brookhaven synchrotron light source

Soft x-ray holographic microscopy is discussed from an experimental point of view. Three series of measurements have been carried out using the Brookhaven 750 MeV storage ring as an x-ray source. Young slits fringes, Gabor (in line) holograms and various data pertaining to the soft x-ray performance of photographic plates are reported. The measurements are discussed in terms of the technique for recording them and the experimental limitations in effect. Some discussion is also given of the issu… more

Date: January 1, 1983

Creator: Howells, M.R.; Iarocci, M.; Kenney, J.; Kirz, J. & Rarback, H.

Item Type: Article

Partner: UNT Libraries Government Documents Department

open access

Limited-angle 3-D reconstructions using Fourier transform iterations and Radon transform iterations

The principles of limited-angle reconstruction of space-limited objects using the concepts of allowed cone and missing cone in Fourier space are discussed. The distortion of a point source resulting from setting the Fourier components in the missing cone to zero was calculated mathematically, and its bearing on the convergence of an iteration scheme involving Fourier transforms was analyzed in detail. It was found that the convergence rate is fairly insensitive to the position of the point sour… more

Date: December 1, 1979

Creator: Tam, K.C. & Perez-Mendez, V.

Item Type: Article

Partner: UNT Libraries Government Documents Department

open access

End-on soft x-ray imaging of Field-Reversed Configurations (FRCs) on the Field-Reversal-C (FRX-C)/ Large Scale Modification (LSM) experiment

Recently, a prototype soft X-ray pinhole camera was fielded on FRX-C/LSM at Los Alamos and TRX at Spectra Technology. The soft X-ray FRC images obtained using this camera stand out in high contrast to their surroundings. It was particularly useful for studying the FRC during and shortly after formation when, at certain operating conditions, flute-like structures at the edge and internal structures of the FRC were observed which other diagnostics could not resolve. Building on this early experie… more

Date: January 1, 1989

Creator: Taggart, D.P.; Gribble, R.J.; Bailey, A.D III & Sugimoto, Satoshi.

Item Type: Article

Partner: UNT Libraries Government Documents Department

open access

Identification and reduction of wakefield effects in the wiggler region of the Los Alamos Free-Electron Laser

Improving the performance of the Los Alamos Free-Electron Laser (FEL) in 1988 involved the identification and reduction of wakefield effects generated in the wiggler region. The wakefield effect was dramatically reduced by inserting a smooth metal tube into the wiggler gap, and the FEL performance was concomitantly improved. 8 refs., 10 figs.

Date: January 1, 1989

Creator: Lumpkin, A. H.; Feldman, D. W.; Warren, R. W.; Stein, W. E. & Chan, K. C. D.

Item Type: Article

Partner: UNT Libraries Government Documents Department

open access

MAESTRO -- A Model and Expert System Tuning Resource for Operators

We have developed MAESTRO, a Model And Expert System Tuning Resource for Operators. It provides a unified software environment for optimizing the performance of large, complex machines, in particular the Advanced Test Accelerator and Experimental Test Accelerator at Lawrence Livermore National Laboratory. The system incorporates three approaches to tuning: a mouse-based manual interface to select and control magnets and to view displays of machine performance; an automation based on cloning the… more

Date: January 1, 1989

Creator: Lager, D.L.; Brand, H.R.; Maurer, W.J.; Coffield, F.E. & Chambers, F.

Item Type: Article

Partner: UNT Libraries Government Documents Department

open access

Proceedings of clinical SPECT (single photon emission computed tomography) symposium

It has been five years since the last in-depth American College of Nuclear Physicians/Society of Nuclear Medicine Symposium on the subject of single photon emission computed tomography (SPECT) was held. Because this subject was nominated as the single most desired topic we have selected SPECT imaging as the basis for this year's program. The objectives of this symposium are to survey the progress of SPECT clinical applications that have taken place over the last five years and to provide practi… more

Date: September 1, 1986

Item Type: Article

Partner: UNT Libraries Government Documents Department

open access

ECE and x-ray image reconstructions of sawtooth oscillations on TFTR

High resolution ECE and X-ray image reconstructions have been made simultaneously during the sawtooth crash in the fast rotating plasma on TFTR. The X-ray tomography is found not the represent flux surfaces but to show metal impurity behavior. The experimental results show that the reconnection process cause the sawtooth crash, even when the crash time is 20 times faster than the Kadomtsev reconnection time. New features are observed during the sawtooth crash, such as an oval shaped hot spot an… more

Date: October 1, 1991

Creator: Nagayama, Y.; McGuire, K.M.; Cavallo, A.; Bitter, M.; Fredrickson, E.D.; Hill, K.W. et al.

Item Type: Report

Partner: UNT Libraries Government Documents Department

open access

Phase 1 report on sensor technology, data fusion and data interpretation for site characterization

In this report we discuss sensor technology, data fusion and data interpretation approaches of possible maximal usefulness for subsurface imaging and characterization of land-fill waste sites. Two sensor technologies, terrain conductivity using electromagnetic induction and ground penetrating radar, are described and the literature on the subject is reviewed. We identify the maximum entropy stochastic method as one providing a rigorously justifiable framework for fusing the sensor data, briefly… more

Date: October 1, 1991

Creator: Beckerman, M.

Item Type: Report

Partner: UNT Libraries Government Documents Department

open access

Scattering and stopping of swift diatomic molecules under Coulomb explosion

The scattering and stopping of the fragments of a fast diatomic molecule under Coulomb explosion has been analyzed theoretically. The central assumption in the scheme is the dominance of Coulomb explosion, while electronic stopping (including wake forces) and elastic scattering are treated as perturbations. Charge exchange has been neglected. Coulomb images of penetration phenomena are heavily distorted. For small penetrated layer thicknesses, images appear contracted in the direction of the mo… more

Date: January 1, 1991

Creator: Sigmund, P. (Odense Univ. (Denmark). Dept. of Physics Argonne National Lab., IL (United States))

Item Type: Article

Partner: UNT Libraries Government Documents Department