Publications

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We have developed a novel experimental technique for direct production of cold molecules using a combination of techniques from atomic optical and molecular physics and physical chemistry. The ability to produce samples of cold molecules has application in a broad spectrum of technical fields high-resolution spectroscopy, remote sensing, quantum computing, materials simulation, and understanding fundamental chemical dynamics. Researchers around the world are currently exploring many techniques for producing samples of cold molecules, but to-date these attempts have offered only limited success achieving milli-Kelvin temperatures with low densities. This Laboratory Directed Research and Development project is to develops a new experimental technique for producing micro-Kelvin temperature molecules via collisions with laser cooled samples of trapped atoms. The technique relies on near mass degenerate collisions between the molecule of interest and a laser cooled (micro-Kelvin) atom. A subset of collisions will transfer all (nearly all) of the kinetic energy from the 'hot' molecule, cooling the molecule at the expense of heating the atom. Further collisions with the remaining laser cooled atoms will thermally equilibrate the molecules to the micro-Kelvin temperature of the laser-cooled atoms.

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This report describes our efforts to quantify the behavior of micro-fabricated THz rectangular waveguides on a configurable, robust semiconductor-based platform. These waveguides are an enabling technology for coupling THz radiation directly from or to lasers, mixers, detectors, antennas, and other devices. Traditional waveguides fabricated on semiconductor platforms such as dielectric guides in the infrared or co-planar waveguides in the microwave regions, suffer high absorption and radiative losses in the THz. The former leads to very short propagation lengths, while the latter will lead to unwanted radiation modes and/or crosstalk in integrated devices. This project exploited the initial developments of THz micro-machined rectangular waveguides developed under the THz Grand Challenge Program, but instead of focusing on THz transceiver integration, this project focused on exploring the propagation loss and far-field radiation patterns of the waveguides. During the 9 month duration of this project we were able to reproduce the waveguide loss per unit of length in the waveguides and started to explore how the loss depended on wavelength. We also explored the far-field beam patterns emitted by H-plane horn antennas attached to the waveguides. In the process we learned that the method of measuring the beam patterns has a significant impact on what is actually measured, and this may have an effect on most of the beam patterns of THz that have been reported to date. The beam pattern measurements improved significantly throughout the project, but more refinements of the measurement are required before a definitive determination of the beam-pattern can be made.

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Cambio is an application intended to automatically read and display any spectrum file of any format in the world that the nuclear emergency response community might encounter. Cambio also provides an analysis capability suitable for HPGe spectra when detector response and scattering environment are not well known. Why is Cambio needed: (1) Cambio solves the following problem - With over 50 types of formats from instruments used in the field and new format variations appearing frequently, it is impractical for every responder to have current versions of the manufacturer's software from every instrument used in the field; (2) Cambio converts field spectra to any one of several common formats that are used for analysis, saving valuable time in an emergency situation; (3) Cambio provides basic tools for comparing spectra, calibrating spectra, and isotope identification with analysis suited especially for HPGe spectra; and (4) Cambio has a batch processing capability to automatically translate a large number of archival spectral files of any format to one of several common formats, such as the IAEA SPE or the DHS N42. Currently over 540 analysts and members of the nuclear emergency response community worldwide are on the distribution list for updates to Cambio. Cambio users come from all levels of government, university, and commercial partners around the world that support efforts to counter terrorist nuclear activities. Cambio is Unclassified Unlimited Release (UUR) and distributed by internet downloads with email notifications whenever a new build of Cambio provides for new formats, bug fixes, or new or improved capabilities. Cambio is also provided as a DLL to the Karlsruhe Institute for Transuranium Elements so that Cambio's automatic file-reading capability can be included at the Nucleonica web site.

This is a dissertation on research conducted studying the dynamic crack initiation toughness of a 4340 steel. Researchers have been conducting experimental testing of dynamic crack initiation toughness, K{sub Ic}, for many years, using many experimental techniques with vastly different trends in the results when reporting K{sub Ic} as a function of loading rate. The dissertation describes a novel experimental technique for measuring K{sub Ic} in metals using the Kolsky bar. The method borrows from improvements made in recent years in traditional Kolsky bar testing by using pulse shaping techniques to ensure a constant loading rate applied to the sample before crack initiation. Dynamic crack initiation measurements were reported on a 4340 steel at two different loading rates. The steel was shown to exhibit a rate dependence, with the recorded values of K{sub Ic} being much higher at the higher loading rate. Using the knowledge of this rate dependence as a motivation in attempting to model the fracture events, a viscoplastic constitutive model was implemented into a peridynamic computational mechanics code. Peridynamics is a newly developed theory in solid mechanics that replaces the classical partial differential equations of motion with integral-differential equations which do not require the existence of spatial derivatives in the displacement field. This allows for the straightforward modeling of unguided crack initiation and growth. To date, peridynamic implementations have used severely restricted constitutive models. This research represents the first implementation of a complex material model and its validation. After showing results comparing deformations to experimental Taylor anvil impact for the viscoplastic material model, a novel failure criterion is introduced to model the dynamic crack initiation toughness experiments. The failure model is based on an energy criterion and uses the K{sub Ic} values recorded experimentally as an input. The failure model is then validated against one class of problems showing good agreement with experimental results.

Presto is a three-dimensional transient dynamics code with a versatile element library, nonlinear material models, large deformation capabilities, and contact. It is built on the SIERRA Framework [1, 2]. SIERRA provides a data management framework in a parallel computing environment that allows the addition of capabilities in a modular fashion. Contact capabilities are parallel and scalable. The Presto 4.14 User's Guide provides information about the functionality in Presto and the command structure required to access this functionality in a user input file. This document is divided into chapters based primarily on functionality. For example, the command structure related to the use of various element types is grouped in one chapter; descriptions of material models are grouped in another chapter. The input and usage of Presto is similar to that of the code Adagio [3]. Adagio is a three-dimensional quasi-static code with a versatile element library, nonlinear material models, large deformation capabilities, and contact. Adagio, like Presto, is built on the SIERRA Framework [1]. Contact capabilities for Adagio are also parallel and scalable. A significant feature of Adagio is that it offers a multilevel, nonlinear iterative solver. Because of the similarities in input and usage between Presto and Adagio, the user's guides for the two codes are structured in the same manner and share common material. (Once you have mastered the input structure for one code, it will be easy to master the syntax structure for the other code.) To maintain the commonality between the two user's guides, we have used a variety of techniques. For example, references to Adagio may be found in the Presto user's guide and vice versa, and the chapter order across the two guides is the same. On the other hand, each of the two user's guides is expressly tailored to the features of the specific code and documents the particular functionality for that code. For example, though both Presto and Adagio have contact functionality, the content of the chapter on contact in the two guides differs. Important references for both Adagio and Presto are given in the references section at the end of this chapter. Adagio was preceded by the codes JAC and JAS3D; JAC is described in Reference 4; JAS3D is described in Reference 5. Presto was preceded by the code Pronto3D. Pronto3D is described in References 6 and 7. Some of the fundamental nonlinear technology used by both Presto and Adagio are described in References 8, 9, and 10. Currently, both Presto and Adagio use the Exodus II database and the XDMF database; Exodus II is more commonly used than XDMF. (Other options may be added in the future.) The Exodus II database format is described in Reference 11, and the XDMF database format is described in Reference 12. Important information about contact is provided in the reference document for ACME [13]. ACME is a third-party library for contact. One of the key concepts for the command structure in the input file is a concept referred to as scope. A detailed explanation of scope is provided in Section 1.2. Most of the command lines in Chapter 2 are related to a certain scope rather than to some particular functionality.

This document is a user's guide for the code Adagio. Adagio is a three-dimensional, implicit solid mechanics code with a versatile element library, nonlinear material models, and capabilities for modeling large deformation and contact. Adagio is a parallel code, and its nonlinear solver and contact capabilities enable scalable solutions of large problems. It is built on the SIERRA Framework [1, 2]. SIERRA provides a data management framework in a parallel computing environment that allows the addition of capabilities in a modular fashion. The Adagio 4.14 User's Guide provides information about the functionality in Adagio and the command structure required to access this functionality in a user input file. This document is divided into chapters based primarily on functionality. For example, the command structure related to the use of various element types is grouped in one chapter; descriptions of material models are grouped in another chapter. The input and usage of Adagio is similar to that of the code Presto [3]. Presto, like Adagio, is a solid mechanics code built on the SIERRA Framework. The primary difference between the two codes is that Presto uses explicit time integration for transient dynamics analysis, whereas Adagio is an implicit code. Because of the similarities in input and usage between Adagio and Presto, the user's guides for the two codes are structured in the same manner and share common material. (Once you have mastered the input structure for one code, it will be easy to master the syntax structure for the other code.) To maintain the commonality between the two user's guides, we have used a variety of techniques. For example, references to Presto may be found in the Adagio user's guide and vice versa, and the chapter order across the two guides is the same. On the other hand, each of the two user's guides is expressly tailored to the features of the specific code and documents the particular functionality for that code. For example, though both Presto and Adagio have contact functionality, the content of the chapter on contact in the two guides differs. Important references for both Adagio and Presto are given in the references section at the end of this chapter. Adagio was preceded by the codes JAC and JAS3D; JAC is described in Reference 4; JAS3D is described in Reference 5. Presto was preceded by the code Pronto3D. Pronto3D is described in References 6 and 7. Some of the fundamental nonlinear technology used by both Presto and Adagio are described in References 8, 9, and 10. Currently, both Presto and Adagio use the Exodus II database and the XDMF database; Exodus II is more commonly used than XDMF. (Other options may be added in the future.) The Exodus II database format is described in Reference 11, and the XDMF database format is described in Reference 12. Important information about contact is provided in the reference document for ACME [13]. ACME is a third-party library for contact. One of the key concepts for the command structure in the input file is a concept referred to as scope. A detailed explanation of scope is provided in Section 1.2. Most of the command lines in Chapter 2 are related to a certain scope rather than to some particular functionality.

The Systems Engineering Management Plan (SEMP) is a comprehensive and effective tool used to assist in the management of systems engineering efforts. It is intended to guide the work of all those involved in the project. The SEMP is comprised of three main sections: technical project planning and control, systems engineering process, and engineering specialty integration. The contents of each section must be tailored to the specific effort. A model outline and example SEMP are provided. The target audience is those who are familiar with the systems engineering approach and who have an interest in employing the SEMP as a tool for systems management. The goal of this document is to provide the reader with an appreciation for the use and importance of the SEMP, as well as provide a framework that can be used to create the management plan.

The PUFF code was originally written and designed to calculate the rise of a large detonation or deflagration non-continuous plume (puff) in the atmosphere. It is based on a buoyant spherical control volume approximation. The theory for the model is updated and presented. The model has been observed to result in what are believed to be unrealistic plume elevation oscillations as the plume approaches the terminal elevation. Recognizing a similarity between the equations for a classical damped spring oscillator and the present model, the plume rise model can be analyzed by evaluating equivalent spring constants and damping functions. Such an analysis suggests a buoyant plume in the atmosphere is significantly under-damped, explaining the occurrence of the oscillations in the model. Based on lessons learned from the analogy evaluations and guided by comparisons with early plume rise data, a set of assumptions is proposed to address the excessive oscillations found in the predicted plume near the terminal elevation, and to improve the robustness of the predictions. This is done while retaining the basic context of the present model formulation. The propriety of the present formulation is evaluated. The revised model fits the vast majority of the existing data to +/- 25%, which is considered reasonable given the present model form. Further validation efforts would be advisable, but are impeded by a lack of quality existing datasets. Copyright © 2008 by ASME.

Iris recognition utilizes distinct patterns found in the human iris to perform identification. Image acquisition is a critical first step towards successful operation of iris recognition systems. However, the quality of iris images required by standard iris recognition algorithms puts hard constraints on the imaging optical systems which have resulted in demonstrated systems to date requiring a relatively short subject stand-off distance. In this paper, we study long-range iris recognition at distances as large as 200 meters, and determine conditions the imaging system must satisfy for identification at longer stand-off distances. © 2009 SPIE.

Effective defense against chemical and biological threats requires an "end-to-end" strategy that encompasses the entire problem space, from threat assessment and target hardening to response planning and recovery. A key element of the strategy is the definition of appropriate system requirements for surveillance and detection of threat agents. Our end-toend approach to venue chem/bio defense is captured in the Facilities Weapons of Mass Destruction Decision Analysis Capability (FacDAC), an integrated system-of-systems toolset that can be used to generate requirements across all stages of detector development. For example, in the early stage of detector development the approach can be used to develop performance targets (e.g., sensitivity, selectivity, false positive rate) to provide guidance on what technologies to pursue. In the development phase, after a detector technology has been selected, the approach can aid in determining performance trade-offs and down-selection of competing technologies. During the application stage, the approach can be employed to design optimal defensive architectures that make the best use of available technology to maximize system performance. This presentation will discuss the end-to-end approach to defining detector requirements and demonstrate the capabilities of the FacDAC toolset using examples from a number of studies for the Department of Homeland Security. © 2009 SPIE.

The practice of mechanical engineering for product development has evolved into a complex activity that requires a team of specialists for success. Sandia National Laboratories (SNL) has product engineers, mechanical designers, design engineers, manufacturing engineers, mechanical analysts and experimentalists, qualification engineers, and others that contribute through product realization teams to develop new mechanical hardware. The goal of SNL's Design Group is to change product development by enabling design teams to collaborate within a virtual model-based environment whereby analysis is used to guide design decisions. Computer-aided design (CAD) models using PTC's Pro/ENGINEER software tools are heavily relied upon in the product definition stage of parts and assemblies at SNL. The three-dimensional CAD solid model acts as the design solid model that is filled with all of the detailed design definition needed to manufacture the parts. Analysis is an important part of the product development process. The CAD design solid model (DSM) is the foundation for the creation of the analysis solid model (ASM). Creating an ASM from the DSM currently is a time-consuming effort; the turnaround time for results of a design needs to be decreased to have an impact on the overall product development. This effort can be decreased immensely through simple Pro/ENGINEER modeling techniques that summarize to the method features are created in a part model. This document contains recommended modeling techniques that increase the efficiency of the creation of the ASM from the DSM.

This report addresses the general data requirements for reliability analysis of fielded wind turbines and other wind plant equipment. The report provides a list of the data needed to support reliability and availability analysis, and gives specific recommendations for a Computerized Maintenance Management System (CMMS) to support automated analysis. This data collection recommendations report was written by Sandia National Laboratories to address the general data requirements for reliability analysis of fielded wind turbines. This report is intended to help the reader develop a basic understanding of what data are needed from a Computerized Maintenance Management System (CMMS) and other data systems, for reliability analysis. The report provides: (1) a list of the data needed to support reliability and availability analysis; and (2) specific recommendations for a CMMS to support automated analysis. Though written for reliability analysis of wind turbines, much of the information is applicable to a wider variety of equipment and a wider variety of analysis and reporting needs.

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