Publications

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Thin-film mechanical properties can be measured using nanoindentation combined with detailed finite element modeling. This technique was used for a study of very fine grained Ni films, formed using pulsed-laser deposition on fused silica, sapphire, and Ni substrates. The grain sizes in the films were characterized by electron microscopy, and the mechanical properties were determined by ultra-low load indentation, analyzed using finite element modeling to separate the mechanical properties of the thin layers from those of the substrates. Some Ni films were deposited at high temperature or annealed after deposition to enlarge the grain sizes. The observed hardnesses and grain sizes in these thin Ni films are consistent with the empirical Hall-Petch relationship for grain sizes ranging from a few micrometers to as small as 10 nm, suggesting that deformation occurs preferentially by dislocation movement even in such nanometer-size grains.

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Enormous interest exists to develop the next generation of an integrated microsystem for chemical and biological analysis ({mu}ChemLab{trademark}) and to further reduce the volume of the system. One approach is to scale down the size of critical components and to explore any pumping mechanism that can minimize the power requirement. Since the majority of the pumping requirement is to overcome the wall resistance in the gas chromatography (GC) column, our attention is to study the gas flow in this GC column. As the column dimension decreases, the gaseous flow will go from a continuum regime into a non-continuum regime; i.e., slip, transition, and free molecular regimes. Thus it is very important to well characterize the gaseous flow in submicron columns and to understand its flow behavior. Specifically, in this study, our focus is to investigate the effects of viscosity, rarefaction, and compressibility as the column dimension decreases. Both theoretical predictions and experimental results will be presented.

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Previous studies of 5,10,15,20-tetraarylporphyrins have shown that the barrier for meso aryl-porphyrin rotation (ΔG‡ROT)) varies as a function of the core substituent M and is lower for a small metal (M = Ni) compared to a large metal (M = Zn) and for a dication (M = 4H2+) versus a free base porphyrin (M = 2H). This has been attributed to changes in the nonplanar distortion of the porphyrin ring and the deformability of the macrocycle caused by the core substituent. In the present work, X-ray crystallography, molecular mechanics (MM) calculations, and variable temperature (VT) 1H NMR spectroscopy are used to examine the relationship between the arylporphyrin rotational barrier and the core substituent M in some novel 2,3,5,7,8,10,12,13,15,17,18,20-dodecaarylporphyrins (DArPs), and specifically in some 5,10,15,20-tetraaryl-2,3,7,8,12,13,17,18-octaphenylporphyrins (TArOPPs), where steric crowding of the peripheral groups always results in a very nonplanar macrocycle. X-ray structures of DArPs indicate differences in the nonplanar conformation of the macrocycle as a function of M, with saddle conformations being observed for M = Zn, 2H or M = 4H2+ and saddle and/or ruffle conformations for M = Ni. VT NMR studies show that the effect of protonation in the TArOPPs is to increase ΔG‡ROT, which is the opposite of the effect seen for the TArPs, and MM calculations also predict a strikingly high barrier for the TArOPPs when M = 4H2+. These and other findings suggest that the aryl-porphyrin rotational barriers in the DArPs are closely linked to the deformability of the macrocycle along a nonplanar distortion mode which moves the substituent being rotated out of the porphyrin plane.

Sandia National Laboratories was tasked by the Japan Nuclear Cycle Development Institute (JNC) to provide assistance in developing an emergency response plan for radioactive material transportation activities. Those tasks included compiling radioactive materials (RAM) transportation accident data from the open literature and databases, investigating emergency response plans for radioactive materials transport in the United States, and developing specific recommendations for the JNC' nuclear material transport emergency response plan, based on information gathered during the first two tasks. These recommendations include developing a RAM database, a public transparency Internet website, an emergency response infrastructure designed specifically for transportation needs, and a clear set of directives to provide authority in the case of transportation accidents or incidents involving RAM.

This report presents background information and methodology for a risk assessment of mixed oxide (MOX) reactor fuel transport in the nation of Japan to support their nuclear energy program. This work includes an extensive literature review, a review of other MOX activities worldwide, a survey of the statutory requirements for transporting nuclear materials, a discussion of risk assessment methodology, and calculation results for specific examples. Typical risk evaluations are given to provide guidance for later risk analyses specific to MOX fuel transport in Japan. This report also includes specific information that will be required for routes, cask types, accident-rate statistics, and population densities along specified routes, along with other detailed information needed for risk analysis studies pertinent to MOX transport in Japan. This information will be used in future specific risk studies.

A novel magnetic resonance imaging (MRI) technique which resolves the separate components of the evolving vertical concentration profiles of 3-component non-colloidal suspensions is described. This method exploits the sensitivity of MRI to chemical differences between the three phases to directly image the fluid phase and one of the solid phases, with the third phase obtained by subtraction. 19F spin-echo imaging of a polytetrafluoroethylene (PTFE) oil was interlaced with 1H SPRITE imaging of low-density polyethylene (LDPE) particles. The third phase was comprised of borosilicate glass spheres, which were not visible while imaging the PTFE or LDPE phases. The method is demonstrated by performing measurements on 2-phase materials containing only the floating (LDPE) particles, with the results contrasted to the experimental behaviour of the individual phases in the full 3-phase system. All experiments were performed using nearly monodisperse particles, with initial suspension volume fractions, φi, of 0.1. © 2003 Elsevier Science (USA). All rights reserved.

The Cooperative Monitoring Center (CMC) promotes collaborations among scientists and researchers in several regions as a means of achieving common regional security objectives. To promote cooperation in South Asia on environmental research, an international working group made up of participants from Bangladesh, India, Nepal, Pakistan, and the United States convened in Kathmandu, Nepal, from February 17-23,2002. The workshop was held to further develop the South Asia Transboundary Water Quality Monitoring (SATWQM) project. The project is sponsored in part by the CMC located at Sandia National Laboratories in Albuquerque, New Mexico through funding provided by the US. Department of State, Regional Environmental Affairs Office, American Embassy, Kathmandu, Nepal, and the National Nuclear Security Administration's (NNSA) Office of Nonproliferation and National Security. This report summarizes the SATWQM project, the workshop objectives, process and results. The long-term interests of the participants are to develop systems for sharing regional environmental information as a means of building confidence and improving relations among South Asian countries. The more immediate interests of the group are focused on activities that foster regional sharing of water quality data in the Ganges and Indus River basins. Issues of concern to the SATWQM network participants include studying the impacts from untreated sewage and industrial effluents, agricultural run-off, salinity increases in fresh waters, the siltation and shifting of river channels, and the environmental degradation of critical habitats such as wetlands, protected forests, and endangered aquatic species conservation areas. The workshop focused on five objectives: (1) a deepened understanding of the partner organizations involved; (2) garnering the support of additional regional and national government and non-government organizations in South Asia involved in river water quality monitoring; (3) identification of sites within the region at which water quality data are to be collected; (4) instituting a data and information collection and sharing process; and, (5) training of partners in the use of water quality monitoring equipment.

This document provides a guide to the deployment of the software verification activities, software engineering practices, and project management principles that guide the development of Accelerated Strategic Computing Initiative (ASCI) applications software at Sandia National Laboratories (Sandia). The goal of this document is to identify practices and activities that will foster the development of reliable and trusted products produced by the ASCI Applications program. Document contents include an explanation of the structure and purpose of the ASCI Quality Management Council, an overview of the software development lifecycle, an outline of the practices and activities that should be followed, and an assessment tool.

Ultra fast, sub-nanosecond (picosecond to femtosecond) duration, laser pulses present unique challenges when performing laser safety analysis involving mode-locked lasers, which operate at pulse repetition frequencies above the critical frequency in the near infrared wavelength bands. Two specific cases are presented, one such case that agrees and one that disagrees with the general rule on critical frequency. The results show that in all cases the appropriate maximum permissible exposure is always the smallest of the values calculated from ANSI rule 1, 2 and 3.

Cavity expansion is a method for modeling the penetration of an axisymmetric or wedge-shaped solid body--a penetrator--into a target by using analytic expressions to capture the effects of the target on the body. Cavity expansion has been implemented as a third-party library (CavityExpansion) that can be used with explicit, transient dynamics codes. This document describes the mechanics of the cavity expansion model implemented as a third-party library. This document also describes the applications interface to CavityExpansion. A set of regression tests has been developed that can be used to test the implementation of CavityExpansion in a transient dynamics code. The mechanics of these tests and the expected results from the tests are described in detail.

Presto is a Lagrangian, three-dimensional explicit, transient dynamics code for the analysis of solids subjected to large, suddenly applied loads. Presto is designed for problems with large deformations, nonlinear material behavior, and contact. There is a versatile element library incorporating both continuum and structural elements. The code is designed for a parallel computing environment. This document describes the input for the code that gives users access to all of the current functionality in the code. Presto is built in an environment that allows it to be coupled with other engineering analysis codes. The input structure for the code, which uses a concept called scope, reflects the fact that Presto can be used in a coupled environment. This guide describes the scope concept and the input from the outermost to the innermost input scopes. Within a given scope, the descriptions of input commands are grouped based on code functionality. For example, all material input command lines are described in a section of the user's guide for all of the material models in the code.

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The Navruz Project is a cooperative, transboundary, river monitoring project involving rivers and institutions in Kazakhstan, Kyrgyzstan, Tajikistan, and Uzbekistan, and facilitated by Sandia National Laboratories in the U.S. The Navruz Project focuses on waterborne radionuclides and metals because of their importance to public health and nuclear materials proliferation concerns in the region. The Project also collects data on basic water quality parameters. Data obtained in this project are shared among all participating countries and the public through a world-wide web site (http://www.cmc.sandia.org/Central/centralasia.html), and are available for use in further studies and in regional transboundary water resource management efforts. This report includes graphs showing selected data from the Fall 2000 and Spring 2001 sampling seasons. These data include all parameters grouped into six regions, including main rivers and some tributaries in the Amu Darya and Syr Darya river systems. This report also assembles all data (in tabular form) generated by the project from Fall 2000 through Fall 2001. This report comes as the second part of a planned three-part reporting process. The first report is the Sampling and Analysis Plan and Operational Manual, SAND 2002-0484. This is the second report.

The three-year LDRD ''CNC Micromachines'' was successfully completed at the end of FY02. The project had four major breakthroughs in spatial motion control in MEMS: (1) A unified method for designing scalable planar and spatial on-chip motion control systems was developed. The method relies on the use of parallel kinematic mechanisms (PKMs) that when properly designed provide different types of motion on-chip without the need for post-fabrication assembly, (2) A new type of actuator was developed--the linear stepping track drive (LSTD) that provides open loop linear position control that is scalable in displacement, output force and step size. Several versions of this actuator were designed, fabricated and successfully tested. (3) Different versions of XYZ translation only and PTT motion stages were designed, successfully fabricated and successfully tested demonstrating absolutely that on-chip spatial motion control systems are not only possible, but are a reality. (4) Control algorithms, software and infrastructure based on MATLAB were created and successfully implemented to drive the XYZ and PTT motion platforms in a controlled manner. The control software is capable of reading an M/G code machine tool language file, decode the instructions and correctly calculate and apply position and velocity trajectories to the motion devices linear drive inputs to position the device platform along the trajectory as specified by the input file. A full and detailed account of design methodology, theory and experimental results (failures and successes) is provided.

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Controlled leak rate devices of fluoroform on the order of 10{sup -8} atm {center_dot} cc sec{sup -1} at 25 C are used to calibrate QC-1 War Reserve neutron tube exhaust stations for leak detection sensitivity. Close-out calibration of these tritium-contaminated devices is provided by the Gas Dynamics and Mass Spectrometry Laboratory, Organization 14406, which is a tritium analytical facility. The mass spectrometric technique used for the measurement is discussed, as is the first principals calculation (pressure, volume, temperature and time). The uncertainty of the measurement is largely driven by contributing factors in the determination of P, V and T. The expanded uncertainty of the leak rate measurement is shown to be 4.42%, with a coverage factor of 3 (k=3).

The dynamic response of critical aerospace components is often strongly dependent upon the dynamic behavior of bolted connections that attach the component to the surrounding structure. These bolted connections often provide the only structural load paths to the component. The bolted joint investigated in this report is an inclined lap-type joint with the interface inclined with respect to the line of action of the force acting on the joint. The accurate analytical modeling of these bolted connections is critical to the prediction of the response of the component to normal and high-level shock environmental loadings. In particular, it is necessary to understand and correctly model the energy dissipation (damping) of the bolted joint that is a nonlinear function of the forces acting on the joint. Experiments were designed and performed to isolate the dynamics of a single bolted connection of the component. Steady state sinusoidal and transient experiments were used to derive energy dissipation curves as a function of input force. Multiple assemblies of the bolted connection were also observed to evaluate the variability of the energy dissipation of the connection. These experiments provide insight into the complex behavior of this bolted joint to assist in the postulation and development of reduced order joint models to capture the important physics of the joint including stiffness and damping. The experiments are described and results presented that provide a basis for candidate joint model calibration and comparison.

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A systematic computational and experimental study is presented on impact generated debris resulting from record-high impact speeds recently achieved on the Sandia three-stage light-gas gun. In these experiments, a target plate of aluminum is impacted by a titanium-alloy flyer plate at speeds ranging from 6.5 to 11 km/s, producing pressures from 1 Mb to over 2.3 Mb, and temperatures as high as 15000 K (>1 eV). The aluminum plate is totally melted at stresses above 1.6 Mb. Upon release, the thermodynamic release isentropes will interact with the vapor dome. The amount of vapor generated in the debris cloud will depend on many factors such as the thickness of the aluminum plate, super-cooling, vaporization kinetics, the distance, and therefore time, over which the impact-generated debris is allowed to expand. To characterize the debris cloud, the velocity history produced by stagnation of the aluminum expansion products against a witness plate is measured using velocity interferometry. X-ray measurements of the debris cloud are also recorded prior to stagnation against an aluminum witness plate. Both radiographs and witness-plate velocity measurements suggest that the vaporization process is both time-dependent and heterogeneous when the material is released from shocked states around 230 GPa. Experiments suggest that the threshold for vaporization kinetics in aluminum should become significant when expanded from shocked states over 230 GPa. Numerical simulations are conducted to compare the measured x-ray radiographs of the debris cloud and the time-resolved experimental interferometer record with calculational results using the 3-D hydrodynamic wavecode, CTH. Results of these experiments and calculations are discussed in this paper.

This report describes the research accomplishments achieved under the LDRD Project ''High-Bandwidth Optical Data Interconnects for Satellite Applications.'' The goal of this LDRD has been to address the future needs of focal-plane-array (FPA) sensors by exploring the use of high-bandwidth fiber-optic interconnects to transmit FPA signals within a satellite. We have focused primarily on vertical-cavity surface-emitting laser (VCSEL) based transmitters, due to the previously demonstrated immunity of VCSELs to total radiation doses up to 1 Mrad. In addition, VCSELs offer high modulation bandwidth (roughly 10 GHz), low power consumption (roughly 5 mW), and high coupling efficiency (greater than -3dB) to optical fibers. In the first year of this LDRD, we concentrated on the task of transmitting analog signals from a cryogenic FPA to a remote analog-to-digital converter. In the second year, we considered the transmission of digital signals produced by the analog-to-digital converter to a remote computer on the satellite. Specifically, we considered the situation in which the FPA, analog-to-digital converter, and VCSEL-based transmitter were all cooled to cryogenic temperatures. This situation requires VCSELs that operate at cryogenic temperature, dissipate minimal heat, and meet the electrical drive requirements in terms of voltage, current, and bandwidth.

This report summarizes the activities of the Computer Science Research Institute (CSRI) at Sandia National Laboratories during the period January 1, 2002 to December 31, 2002. During this period the CSRI hosted 172 visitors representing 95 universities, companies or laboratories. Of these 56 were summer students or faculty. The CSRI also organized and hosted five workshops with 171 participants. Of these 94 attendees were from 64 universities, companies or laboratories, and 77 were from Sandia. Finally, the CSRI sponsored 14 long-term collaborative research projects.

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Quantum dot nanostructures were investigated experimentally and theoretically for potential applications for optoelectronic devices. We have developed the foundation to produce state-of-the-art compound semiconductor nanostructures in a variety of materials: In(AsSb) on GaAs, GaSb on GaAs, and In(AsSb) on GaSb. These materials cover a range of energies from 1.2 to 0.7 eV. We have observed a surfactant effect in InAsSb nanostructure growth. Our theoretical efforts have developed techniques to look at the optical effects induced by many-body Coulombic interactions of carriers in active regions composed of quantum dot nanostructures. Significant deviations of the optical properties from those predicted by the ''atom-like'' quantum dot picture were discovered. Some of these deviations, in particular, those relating to the real part of the optical susceptibility, have since been observed in experiments.

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