Publications

This paper examines the role of the control objective and the control time in determining fuel-optimal actuator placement for structural vibration suppression. A general theory is developed that can be easily extended to include alternative performance metrics such as energy and time-optimal control. The performance metric defines a convex admissible control set which leads to a max-min optimization problem expressing optimal location as a function of initial conditions and control time. A solution procedure based on a nested Genetic Algorithm is presented and applied to an example problem. Results indicate that the optimal locations vary widely as a function of control time and initial conditions.

When restricted to cost arrays possessing the sum Monge property, many combinatorial optimization problems with sum objective functions become significantly easier to solve. Examples include the usual sum-objective-function versions of the assignment problem, the transportation problem, the traveling-salesman problem, and several shortest-path problems. Furthermore, the more general algebraic assignment and transportation problems, which are formulated in terms of an ordered commutative semigroup (H, *, {le}), are similarly easier to solve given cost arrays possessing the corresponding algebraic Monge property, which requires that for all i < k and j < {ell}, a[i,j] * a[k,{ell}] {le} a[i,{ell}] * a[k,j]. In this paper, we show that Monge-array results for two sum-of-edge-costs shortest-path problems can likewise be extended to a general algebraic setting, provided the problems` ordered commutative semigroup (H, *, {le}) satisfies one additional restriction. We also show how our algorithms can be modified to solve certain bottleneck shortest-path problems, even though the ordered commutative semigroup ({Re}, max, {le}) naturally associated with bottleneck problems does not satisfy our additional restriction. We also provide improved algorithms for several other bottleneck combinatorial optimization problems whose cost arrays possess the strict bottleneck Monge property. Finally, we show how our bottleneck shortest-path techniques can be used to obtain fast algorithms for a variant of Hirschberg and Larmore`s optimal paragraph formation problem, a processor-allocation problem first formulated by Bokhari, and a special case of the bottleneck traveling-salesman problem.

Robotics technology is being developed to assist in remediating high-level radioactive wastes stored in large tanks at the Department of Energy`s Hanford, Washington facility. Remediation activities will likely employ a remotely controlled long reach manipulator, capable of extending over 40 feet from its base, to deploy remediation end-effectors and sensors. Waste inside the tanks consists of hazardous vapor, liquid, sludge, solidified crystal, and various steel pipes and miscellaneous hardware. On November 10--12, 1992, a demonstration by Sandia National Laboratories of environmental sensor scanning and robot manipulated steel pipe cutting was performed on a tank mockup located at the Hanford facility. This paper describes the Sandia developed technology implemented at this demonstration.

The Analytic System and Software for Evaluation of Safeguards and Security (ASSESS) Facility module records site information in the path elements and areas of an Adversary Sequence Diagram. The ASSESS Outsider evaluation module takes this information and first calculates performance values describing how much detection and delay is assigned at each path element and then uses the performance values to determine most-vulnerable paths. This paper discusses new Outsider capabilities that allow the user to view how elements are being defeated and to modify some of these values in Outsider. Outsider now displays how different path element segments are defeated and contrasts the probability of detection for alternate methods of defeating a door (e.g., the lock or the door face itself). The user can also override element segment delays and detection probabilities directly during analysis in Outsider. These capabilities allow users to compare element performance and to verify correct path element performance for all elements, not just those on the most-vulnerable path as is the case currently. Improvements or reductions in protection can be easily checked without creating a set of new facility files to accomplish it.

Sandia National Laboratories (SNL) has shown that an automated personnel tracking and material monitoring system enhances protection of sensitive and classified parts against an insider. Such a system also significantly reduces the number of required, manual physical inventories at Department of Energy (DOE) sites while increasing assurance that material has not been diverted. SNL`s Insider Technology Department developed and is enhancing its generic, real-time, personnel tracking and material monitoring system. The system consists of facility selectable modules. This paper presents an overview of the modules, evaluation results, user`s suggestions, and future modules.

Although plasma cleaning is a recognized substitute for solvent cleaning in removing organic contaminants, some universal problems in plasma cleaning processes prevent wider use of plasma techniques. Lack of understanding of the fundamental mechanisms of the process, unreliable endpoint detection techniques, and slow process times make plasma cleaning processes less than desirable. Our approach to address these plasma cleaning problems is described. A comparison of plasma cleaning rates of oxygen and oxygen/sulfur hexafluoride gases shows that fluorine-containing plasmas can enhance etch rates by 400% over oxygen alone. A discussion of various endpoint indication techniques is discussed and compared for application suitability. Work toward a plasma cleaning database is discussed. In addition to the global problems of plasma cleaning, an experiment where the specific mixed-waste problem of removal of machine oils from radioactive scrap metal is discussed.

The US Department of Energy has required radiological sabotage vulnerability assessments to be conducted for years. However, the exact methodology to be used in this type of analysis still remains somewhat elusive. Therefore, there is tremendous variation in the methodologies and assumptions used to determine release levels and doses potentially affecting the health and safety of the public. In some cases, there are three orders of magnitude difference in results for dispersal of similar materials under similar meteorological conditions. To address this issue, the authors have developed an approach to standardizing radiological sabotage target analysis that starts by addressing basic assumptions and then directs the user to some recommended computerized analytical tools. Results from different dispersal codes are also compared in this analysis.

The ASSESS Neutralization Analysis module (Neutralization) is part of Analytic System and Software for Evaluation of Safeguards and Security, ASSESS, a vulnerability assessment tool. Neutralization models a fire fight engagement between security inspectors (SIs) and adversaries. Since version 1.0 of Neutralization was released in 1989, experience has shown that several features of the user interface should be improved. This report describes the improvements that have been implemented, which simplify operation by consolidating all capabilities under a single mode of operation, remove many restrictions on editing, and concentrate more information into fewer types of printed reports. Every adversary and SI combatant is named and described individually. Time to communicate orders is specified for each SI combatant. Adversaries and SIs can be reinforced. SI posting as well deployment destination is labeled. Scenario details can be revised without losing all completed event information. New on-screen summaries spell out characteristics, minimizing abbreviations. Neutralization will read files created by the previous version and permit the user to enter the additional labels supported in the new version. As described here, Neutralization now has an interface that handles more information, but is easier and faster to use.

Short communication.

This paper describes a passive tamper-indicating secure container that has been designed to demonstrate concepts, features, and materials that can be used in passive container applications. (In a passive security system, physical phenomena provide visual indication of tampering.) The basic container {open_quotes}volume within a volume{close_quotes} assembly consists of a transparent plastic outer container and an aluminum inner container. Both containers incorporate passive, fingerprinted layers as part of the tamper-indicating container system. Many of the tamper-indicating features can be visually inspected without disassembling the container. The status of container development and potential applications for the container are addressed.

A radiological safety evaluation is performed to determine the impacts of Exploratory Studies Facility (ESF) design changes on the preclosure public radiological safety for a potential nuclear waste repository at Yucca Mountain, Nevada. Although the ESF design has undergone significant modification, incorporation of the modified design requires only modest changes to the conceptual repository configuration. To the extent feasible, the results of earlier safety evaluations presented in SAND84-2641, SAND88-7061, and SAND89-7024, which were based on the original ESF configuration, are compared with the results for the modified configuration. This comparison provides an estimate of the range of analysis uncertainty. This preliminary analysis indicates that there are no Q-scenarios, which are defined as those scenarios with a net occurrence probability of greater than 10{sup {minus}6}/yr and produce a radiological dose at the 5-km controlled area boundary of greater than 0.5 rem. The analysis yielded estimates for an underground accident of a probability of 3.8 {times} 10{sup {minus}15}/yr and a dose of 1.5 rem. For a surface-initiated accident, a probability of 1.5 {times} 10{sup {minus}12}/yr and a dose of 0.6 rem was estimated.

Tunnels buried deep within the earth constitute an important class geomechanics problems. Two numerical techniques used for the analysis of geomechanics problems, the finite element method and the boundary element method, have complementary characteristics for applications to problems of this type. The usefulness of combining these two methods for use as a geomechanics analysis tool has been recognized for some time, and a number of coupling techniques have been proposed. However, not all of them lend themselves to efficient computational implementations for large-scale problems. This report examines a coupling technique that can form the basis for an efficient analysis tool for large scale geomechanics problems through the use of an iterative equation solver.

Human Instrusion into the potential repository at Yucca Mountain, Nevada, was modeled in the Total-System Performance Assessment (``TSPA-91``) recently completed for the Yucca Mountain Site Characterization Project Office of the DOE. The scenario model assumed that the repository would be penetrated at random locations by a number of boreholes drilled using twentieth-century rotary drilling techniques.

This report brings into focus the results of numerous studies that have addressed issues associated with the validity of assumptions which are used to justify reducing the dimensionality of numerical calculations of water flow through Yucca Mountain, NV. it is shown that, in many cases, one-dimensional modeling is more rigorous than previously assumed.

Sandia National Laboratories was requested to establish the FAA Aging Aircraft Nondestructive Inspection (NDI) Development and Demonstration Center. The Center is housed in a hangar at the Albuquerque International Airport and owns its own aged transport airplane. The Center`s work encompasses research and development in enhanced structural inspection. The goals of the Center are to: promote NDI technology development and maturation; help transfer new nondevelopment item technology to the hangar floor; validate NDI techniques; assess reliability or probability of detection of NDI processes. An important part of this project will be to make sure that the cost of implementation and operation of any technique is seriously considered and that techniques are usable in the field. Among the initial techniques to be evaluated are: enhanced visual, magneto-optic eddy current; coherent optics; ultrasonics; thermographics; eddy current scanners; experimental modal analysis. This project is a perfect example of how Development Testing draws on its own resources and teams up with others, as necessary, to get the job done. In this case, New Mexico State University and a private company, Science Applications International Corporation, are assisting.

This cautionary paper reminds users of quartz shock stress gauges that sensors that ignore the design rules of the ``Sandia quartz gauge`` may produce substantial and unrecognized deviations from normal sensitivity, waveform distortion, and anomalous conduction. Each deviant design must be extensively characterized. The consequence of non-standard gauge designs, like the ``shorted quartz gauge`` designs, are given for prompt response to pulsed radiation while stressed.

PVDF piezoelectric polymer shock stress sensors have been used to measure the shock and impulse generated by soft X-rays and by filter debris in the SATURN Plasma Radiation Source at Sandia National Laboratories, NM. SATURN was used to generate 30 to 40 kJ, 20-ns duration, line radiation at 2 to 3 keV. Fluence on samples was nominally 40, 200, and 400 kJ/m{sup 2} (1, 5, and 10 cal/cm{sup 2}). Measurements of X-ray induced material shock response exposing both aluminum and PMMA acrylic samples agree well with companion measurements made with single crystal X-cut quartz gauges. Time-of-flight, stress, and impulse produced by Kimfol (polycarbonate/aluminum) filter debris were also measured with the PVDF gauges.

PVDF shock stress sensors were subjected to X-ray deposition at nominal absorbed levels of 1, 1{1/2}, 3, and 5 cal/gm (SiO{sub 2} equiv.) and to neutron fluence above 10{sup 13} n/cm{sup 2} while stressed at a peak level of about 2 GPa. Moderate transitory electrical noise that occurred briefly during the radiation did not persist. PVDF shock sensors with aluminum electrodes appear satisfactory for measurement within these exposure limits. Reference quartz gauges were severely affected.

Sandia National Laboratories has the qualification evaluation responsibility for the design of certain components intended for use in nuclear weapons. Specific techniques in assurance and assessment have been developed to provide the quality evidence that the software has been properly qualified for use. Qualification Evaluation is a process for assessing the suitability of either a process used to develop or manufacture the product, or the product itself. The qualification process uses a team approach to evaluating a product or process, chaired by a Quality Assurance professional, with other members representing the design organization, the systems organization, and the production agency. Suitable for use implies that adequate and appropriate definition and documentation has been produced and formally released, adequate verification and validation activities have taken place to ensure proper operation, and the software product meets all requirements, explicitly or otherwise.

Upon achieving ignition and gain, the Laboratory Microfusion Facility (LMF) will be a major tool for Inertial Confinement Fusion (ICF) research and defense applications. Our concept for delivering {approximately}10 MJ with a peak on-target light ion power of {approximately}700 TW involves a multi-modular approach using an extension of the compact inductively isolated cavity and Magnetically Insulated Transmission Line (MITL) Voltage Adder technology that is presently being used in several large accelerators at Sandia/New Mexico. The LMF driver design consists of twelve 8-TW and twelve 38-TW accelerating modules, each with a triaxial MITL/Adder that delivers power to a two stage ion extraction diode. The desired energy, power pulse shape, and deposition uniformity on an ICF target can be achieved by controlling the energy and firing sequence of the ``A`` and ``B`` accelerator modules, plus optimizing the beam transport and focusing. The multi-modular configuration reduces risk by not scaling significantly beyond existing machines and offers the flexibility of staged construction. It permits modular driver testing at the full operating level required by the LMF.

Reconsolidated salt is a fundamental component of the permanent seals for the Waste Isolation Pilot Plant. As regulations are currently understood and seal concepts envisioned, emplaced salt is the sole long-term seal component designed to prevent the shafts from becoming preferred pathways for rating gases or liquids. Studies under way in support of the sealing function of emplaced salt include laboratory testing of crushed salt small-scale in situ tests, constitutive modeling of crushed salt, calculations of the opening responses during operation and closure, and design practicalities including emplacement techniques. This paper briefly summarizes aspects of these efforts and key areas of future work.

In the verification technology arena, there is a pressing need for surveillance and monitoring equipment that produces authentic, verifiable records of observed activities. Such a record provides the inspecting party with confidence that observed activities occurred as recorded, without undetected tampering or spoofing having taken place. The secure authenticated video equipment (SAVE) system provides an authenticated series of video images of an observed activity. Being self-contained and portable, it can be installed as a stand-alone surveillance system or used in conjunction with existing monitoring equipment in a non-invasive manner. Security is provided by a tamper-proof camera enclosure containing a private, electronic authentication key. Video data is transferred communication link consisting of a coaxial cable, fiber-optic link or other similar media. A video review station, located remotely from the camera, receives, validates, displays and stores the incoming data. Video data is validated within the review station using a public key, a copy of which is held by authorized panics. This scheme allows the holder of the public key to verify the authenticity of the recorded video data but precludes undetectable modification of the data generated by the tamper-protected private authentication key.

A multiphase mixture model is presented to describe shock compression of highly porous, multi-component powders. Volume fractions are represented as independent kinematic variables and thermodynamically-admissible phase interaction constitutive models are formulated in the context of a three phase system. Numerical solutions of the multiphase flow equations simulated impact on a porous layer of mixed powders of Al and Fe{sub 2}O{sub 3}. The multiphase model predicts dispersive compaction waves which have features similar to observed time-resolved pressure measurements.

GENSHELL is a three-dimensional shell mesh generation program. The three-dimensional shell mesh is generated by mapping a two-dimensional quadrilateral mesh into three dimensions according to one of several types of transformations: translation, mapping onto a spherical, ellipsoidal, or cylindrical surface, and mapping onto a user-defined spline surface. The generated three-dimensional mesh can then be reoriented by offsetting, reflecting about an axis, revolving about an axis, and scaling the coordinates. GENSHELL can be used to mesh complex three-dimensional geometries composed of several sections when the sections can be defined in terms of transformations of two-dimensional geometries. The code GJOIN is then used to join the separate sections into a single body. GENSHELL updates the EXODUS quality assurance and information records to help track the codes and files used to generate the mesh. GENSHELL reads and writes two-dimensional and three-dimensional mesh databases in the GENESIS database format; therefore, it is compatible with the preprocessing, postprocessing, and analysis codes in the Sandia National Laboratories Engineering Analysis Code Access System (SEACAS).

1990 amendments to the Clean Air Act have created the need for instruments capable of monitoring volatile organic compounds (VOCS) in public air space in an unattended and low cost manner. The purpose of the study was to develop and demonstrate the capability to do long term automatic and unattended ambient air monitoring using an inexpensive portable analytic system at a commercial manufacturing plant site. A gas chromatograph system personal computer hardware, meteorology tower & instruments, and custom designed hardware and software were developed. Comparison with an EPA approved method was performed. The system was sited at an aircraft engines manufacturing site and operated in a completely unattended mode for 60 days. Two VOCs were monitored every 30 minutes during the 24hr day. Large variation in the concentration from 800ppb to the limits of detection of about 10ppb were observed. Work to increase the capabilities of the system is ongoing.