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A report is made on the demonstration of a first-generation Wall Surveyor that is capable of surveying the interior and thickness of a stone, brick, or cement wall. LLNL`s Micropower Impulse Radar is used, based on emitting and detecting very low amplitude and short microwave impulses (MIR rangefinder). Six test walls were used. While the demonstrator MIR Wall Surveyor is not fieldable yet, it has successfully scanned the test walls and produced real-time images identifying the walls. It is planned to optimize and package the evaluation wall surveyor into a hand held unit.

The Lawrence Livermore National Laboratory (LLNL) has developed radar and imaging technologies with potential applications in mine detection by the armed forces and other agencies involved in determining efforts. These new technologies use a patented ultra-wideband (impulse) radar technology that is compact, low-cost, and low power. Designated as Micropower hnpulse Radar, these compact, self-contained radars can easily be assembled into arrays to form complete ground penetrating radar imaging systems. LLNL has also developed tomographic reconstruction and signal processing software capable of producing high-resolution 2-D and 3-D images of objects buried in materials like soil or concrete from radar data. Preliminary test results have shown that a radar imaging system using these technologies has the ability to image both metallic and plastic land mine surrogate targets buried in 5 to 10 cm of moist soil. In dry soil, the system can detect buried objects to a depth of 30 cm and more. This report describes our initial test results and plans for future work.

The Lawrence Livermore National Laboratory (LLNL) has developed radar and imaging technologies with potential applications in mine detection by the armed forces and other agencies involved in demining efforts. These new technologies use a patented ultra-wideband (impulse) radar technology that is compact, low-cost, and low power. Designated as Micropower Impulse Radar, these compact, self-contained radars can easily be assembled into arrays to form complete ground penetrating radar imaging systems. LLNL has also developed tomographic reconstruction and signal processing software capable of producing high-resolution 2-D and 3-D images of objects buried in materials like soil or concrete from radar data. Preliminary test results have shown that a radar imaging system using these technologies has the ability to image both metallic and plastic land mine surrogate targets buried in 5 to 10 cm of moist soil. In dry soil, the system can detect buried objects to a depth of 30 cm and more. This report describes LLNL`s unique capabilities and technologies that can be applied to the demining problem.

This document establishes the software design, nomenclature, and conventions for industrial Computed Tomography (CT) used in the Nondestructive Evaluation Section at Lawrence Livermore National Laboratory. It is mainly a users guide to the technical use of the CT computer codes, but also presents a proposed standard for describing CT experiments and reconstructions. Each part of this document specifies different aspects of the CT software organization. A set of tables at the end describes the CT parameters of interest in our project. 4 refs., 6 figs., 1 tab.

Radioscopy and transmission x-ray computerized tomography (TCT) were used to analyze as simulated waste canister. This study was performed to demonstrate the qualitative and quantitative possibilities obtained by TCT scanners over radioscopy and how TCT can be applied toward the solution of materials and waste management problems. This report provides a brief summary of the scanner (CATALYST) used, a description of the waste canister and its contents, and an analysis of three radiographic views and the two scans obtained at two different slice planes on the canister. The usefulness of TCT is demonstrated by how well it reveals the interior details and spatial positions of items within the simulated waste canister. This paper ends with a summary of this study and what further development is required for this technology to be better used in materials and waste management. 9 refs., 13 figs.

In x-ray and ion-beam computerized tomography, there are a number of reconstruction effects, manifested as artifacts, that can be attributed to the geometry of the experimental setup and of the object being scanned. In this work, we will examine four geometric effects that are common to first-and third-generation (parallel beam, 180 degree) computerized tomography (CT) scanners and suggest solutions for each problem. The geometric effects focused on in this paper are: X-pattern'' artifacts (believed to be caused by several errors), edge-generated ringing artifacts (due to improper choice of the reconstruction filter and cutoff frequency), circular-ring artifacts (caused by employing uncalibrated detectors), and tuning-fork artifacts (generated by an incorrectly specified center-of-rotation). Examples of four effects are presented. The X-pattern and edge-generated ringing artifacts are presented with actual experimental data introducing the artifact. given the source of the artifact, we present simulated data designed to replicate the artifact. Finally, we suggest ways to reduce or completely remove these artifacts. The circular-ring and tuning-fork artifacts are introduced with actual experimental data as well, while digital signal processing solutions are employed to remove the artifacts from the data. 15 refs., 12 figs.

The need exists for methods to simplify groundwater contaminant transport models. Reduced-order models are needed in risk assessments for licensing and regulating long-term nuclear waste repositories. Such models will be used in Monte Carlo simulations to generate probabilities of nuclear waste migration in aquifers at candidate repository sites in the United States. In this feasibility study we focused on groundwater flow rather than contaminant transport because the flow problem is more simple. A pump-drawdown test is modeled with a reduced-order set of ordinary differential equations obtained by differencing the partial differential equation. We determined the accuracy of the reduced model by comparing it with the analytic solution for the drawdown test. We established an accuracy requirement of 2% error at the single observation well and found that a model with only 21 states satisfied that criterion. That model was used in an extended Kalman filter with synthesized measurement data from one observation well to identify transmissivity within 1% error and storage coefficient within 10% error. We used several statistical tests to assess the performance of the estimator/identifier and found it to be satisfactory for this application. This feasibility study highlighted problems known to others who have attempted to apply modern systems methods to hydrological problems and has led to related research studies at our laboratory.

SIG is a general-purpose customizable signal processing, analysis, and display program. Its main purpose is to perform manipulations on time- and frequency-domain signals, however it accommodates other representations for data such as transfer function polynomials. Signal processing operations include digital filtering, auto/ cross spectral density, transfer function/impulse response, convolution, forward/inverse Fourier transforms, deconvolution, identification, and simulation with ARMAX models. Graphics operations display signals and spectra with capability for cursor zoom, families of curves, and multiple viewport plots. There are two user interfaces, a menu mode for occasional users, and a command mode for daily users. Capability exists for defining custom menus, new commands, and incorporating user-written software.

The extended Kalman filter (EKF) has often been used as a parameter identifier for linear systems. Ljung has proposed a correction to the EKF that would allow the algorithm to asymptotically converge to unbiased parameter estimates. In this paper a continuous-discrete version of the algorithm is presented and found to have similar convergence properties. Discussion of the advantages of using continuous time models follows. Also included is a discussion of the computer methods used to propagate the differential equations found in the algorithm.

We have applied state-space methods to the analysis and measurement of the dynamic response of mechanical structures. Our basic approach has been to use finite element structural dynamics models and convert the geometric description of the structure to produce a set of 2nd order matrix differential equations. The equations are then transformed into state-space form for input to a large-scale discrete-time linear Kalman filter. The filter has been implemented on the CRAY-1 computer which has sufficient capacity for a system of 500 states. The actual testing and analysis of a sample structure subjected to vibration tests is discussed. The state estimates are compared post-facto to a finite element model output to evaluate estimator performance. The state estimator consisted of 72 states predicting nodal displacements.

We have designed computer programs to simulate ultrasound projection scans and to reconstruct the tomographic planar image. We have also used the reconstruction algorithm on actual test data and have obtained a crude but promising image. 11 refs., 9 figs.