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Unproven screening devices threaten the lives of police and military

Murray, Dale W.

In a world plagued with improvised explosive devices, drugs and dangerous people, the desire to field technology to protect our police and military is providing a fertile market for the proliferation of protection technologies that range from the unproven to the disproven. The market place is currently being flooded with detection equipment making inflated and inaccurate marketing claims of high reliably, high detection probabilities, and ease of operation - all while offering detection capabilities at safe distances. The manufacturers of these devices have found a willing global marketplace, which includes some of the most dangerous places in the world. Despite a wealth of contradictory performance and testing data available on the Internet, sales of these devices remain brisk and profitable. Rather than enhancing the security of police and military personnel, the reliance on these unproven and disproven devices is creating a sense of false security that is actually lowering the safety of front-line forces in places like Iraq and Afghanistan. This paper addresses the development and distribution history of some of these devices and describes the testing performed by Sandia National Laboratories in Albuquerque, and other reputable testing agencies that illustrate the real danger in using this kind of unproven technology.

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TYPE Conference YEAR 2010
OSTI

Crystal coherence length effects on the infrared optical response of MgO thin films

Ginn, James C.; Kotula, Paul G.; Rodriguez, Marko A.; Clem, Paul; Sinclair, Michael B.

The role of crystal coherence length on the infrared optical response of MgO thin films was investigated with regard to Reststrahlen band photon-phonon coupling. Preferentially (001)-oriented sputtered and evaporated ion-beam assisted deposited thin films were prepared on silicon and annealed to vary film microstructure. Film crystalline coherence was characterized by x-ray diffraction line broadening and transmission electron microscopy. The infrared dielectric response revealed a strong dependence of dielectric resonance magnitude on crystalline coherence. Shifts to lower transverse optical phonon frequencies were observed with increased crystalline coherence. Increased optical phonon damping is attributed to increasing granularity and intergrain misorientation.

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TYPE Conference YEAR 2010
OSTI

Multiple model inference

Swiler, Laura P.; Urbina, Angel U.

This paper compares three approaches for model selection: classical least squares methods, information theoretic criteria, and Bayesian approaches. Least squares methods are not model selection methods although one can select the model that yields the smallest sum-of-squared error function. Information theoretic approaches balance overfitting with model accuracy by incorporating terms that penalize more parameters with a log-likelihood term to reflect goodness of fit. Bayesian model selection involves calculating the posterior probability that each model is correct, given experimental data and prior probabilities that each model is correct. As part of this calculation, one often calibrates the parameters of each model and this is included in the Bayesian calculations. Our approach is demonstrated on a structural dynamics example with models for energy dissipation and peak force across a bolted joint. The three approaches are compared and the influence of the log-likelihood term in all approaches is discussed.

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TYPE Conference YEAR 2010
OSTI

Scalable tensor factorizations with incomplete data

Kolda, Tamara G.; Dunlavy, Daniel M.

The problem of incomplete data - i.e., data with missing or unknown values - in multi-way arrays is ubiquitous in biomedical signal processing, network traffic analysis, bibliometrics, social network analysis, chemometrics, computer vision, communication networks, etc. We consider the problem of how to factorize data sets with missing values with the goal of capturing the underlying latent structure of the data and possibly reconstructing missing values (i.e., tensor completion). We focus on one of the most well-known tensor factorizations that captures multi-linear structure, CANDECOMP/PARAFAC (CP). In the presence of missing data, CP can be formulated as a weighted least squares problem that models only the known entries. We develop an algorithm called CP-WOPT (CP Weighted OPTimization) that uses a first-order optimization approach to solve the weighted least squares problem. Based on extensive numerical experiments, our algorithm is shown to successfully factorize tensors with noise and up to 99% missing data. A unique aspect of our approach is that it scales to sparse large-scale data, e.g., 1000 x 1000 x 1000 with five million known entries (0.5% dense). We further demonstrate the usefulness of CP-WOPT on two real-world applications: a novel EEG (electroencephalogram) application where missing data is frequently encountered due to disconnections of electrodes and the problem of modeling computer network traffic where data may be absent due to the expense of the data collection process.

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TYPE Conference YEAR 2010
OSTI

Shifted power method for computing tensor eigenvalues

Kolda, Tamara G.; Mayo, Jackson R.

Recent work on eigenvalues and eigenvectors for tensors of order m >= 3 has been motivated by applications in blind source separation, magnetic resonance imaging, molecular conformation, and more. In this paper, we consider methods for computing real symmetric-tensor eigenpairs of the form Ax{sup m-1} = lambda x subject to ||x||=1, which is closely related to optimal rank-1 approximation of a symmetric tensor. Our contribution is a shifted symmetric higher-order power method (SS-HOPM), which we show is guaranteed to converge to a tensor eigenpair. SS-HOPM can be viewed as a generalization of the power iteration method for matrices or of the symmetric higher-order power method. Additionally, using fixed point analysis, we can characterize exactly which eigenpairs can and cannot be found by the method. Numerical examples are presented, including examples from an extension of the method to finding complex eigenpairs.

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TYPE Conference YEAR 2010
OSTI

Morphological evolution of Ag2Te precipitates in thermoelectric PbTe

Sugar, Joshua D.; Hekmaty, Michelle A.; Medlin, Douglas L.

The precipitation of Ag{sub 2}Te in a PbTe matrix is investigated using electron microscopy and atom probe tomography. We observe the formation of oriented nanoscale Ag{sub 2}Te precipitates in PbTe. These precipitates initially form as coherent spherical nanoparticles and evolve into flattened semi-coherent disks during coarsening. This change in morphology is consistent with equilibrium shape theory for coherently strained precipitates. Upon annealing at elevated temperatures these precipitates eventually revert to an equiaxed morphology. We suggest this shape change occurs once the precipitates grow beyond a critical size, making it favorable to relieve the elastic coherency strains by forming interfacial misfit dislocations. These investigations of the shape and coherency of Ag{sub 2}Te precipitates in PbTe should prove useful in the design of nanostructured thermoelectric materials.

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TYPE Conference YEAR 2010
OSTI

Cyber security analysis testbed : combining real, emulation, and simulation

Van Leeuwen, Brian P.; Urias, Vincent; Eldridge, John M.; Villamarin, Charles

Cyber security analysis tools are necessary to evaluate the security, reliability, and resilience of networked information systems against cyber attack. It is common practice in modern cyber security analysis to separately utilize real systems of computers, routers, switches, firewalls, computer emulations (e.g., virtual machines) and simulation models to analyze the interplay between cyber threats and safeguards. In contrast, Sandia National Laboratories has developed novel methods to combine these evaluation platforms into a hybrid testbed that combines real, emulated, and simulated components. The combination of real, emulated, and simulated components enables the analysis of security features and components of a networked information system. When performing cyber security analysis on a system of interest, it is critical to realistically represent the subject security components in high fidelity. In some experiments, the security component may be the actual hardware and software with all the surrounding components represented in simulation or with surrogate devices. Sandia National Laboratories has developed a cyber testbed that combines modeling and simulation capabilities with virtual machines and real devices to represent, in varying fidelity, secure networked information system architectures and devices. Using this capability, secure networked information system architectures can be represented in our testbed on a single, unified computing platform. This provides an 'experiment-in-a-box' capability. The result is rapidly-produced, large-scale, relatively low-cost, multi-fidelity representations of networked information systems. These representations enable analysts to quickly investigate cyber threats and test protection approaches and configurations.

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TYPE Conference YEAR 2010
OSTI

Survey of basic XRD applications

Rodriguez, Mark A.

This 1/2 day workshop will survey various applications of XRD analysis, including in-situ analyses and neutron diffraction. The analyses will include phase ID, crystallite size and microstrain, preferred orientation and texture, lattice parameters and solid solutions, and residual stress. Brief overviews of high-temperature in-situ analysis, neutron diffraction and synchrotron studies will be included.

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TYPE Conference YEAR 2010
OSTI

Network algorithms for information analysis using the Titan Toolkit

Wylie, Brian N.; Wilson, Andrew T.

The analysis of networked activities is dramatically more challenging than many traditional kinds of analysis. A network is defined by a set of entities (people, organizations, banks, computers, etc.) linked by various types of relationships. These entities and relationships are often uninteresting alone, and only become significant in aggregate. The analysis and visualization of these networks is one of the driving factors behind the creation of the Titan Toolkit. Given the broad set of problem domains and the wide ranging databases in use by the information analysis community, the Titan Toolkit's flexible, component based pipeline provides an excellent platform for constructing specific combinations of network algorithms and visualizations.

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TYPE Conference YEAR 2010
OSTI

Network design optimization of fuel cell systems and distributed energy devices

Colella, Whitney G.

This research explores the thermodynamics, economics, and environmental impacts of innovative, stationary, polygenerative fuel cell systems (FCSs). Each main report section is split into four subsections. The first subsection, 'Potential Greenhouse Gas (GHG) Impact of Stationary FCSs,' quantifies the degree to which GHG emissions can be reduced at a U.S. regional level with the implementation of different FCS designs. The second subsection, 'Optimizing the Design of Combined Heat and Power (CHP) FCSs,' discusses energy network optimization models that evaluate novel strategies for operating CHP FCSs so as to minimize (1) electricity and heating costs for building owners and (2) emissions of the primary GHG - carbon dioxide (CO{sub 2}). The third subsection, 'Optimizing the Design of Combined Cooling, Heating, and Electric Power (CCHP) FCSs,' is similar to the second subsection but is expanded to include capturing FCS heat with absorptive cooling cycles to produce cooling energy. The fourth subsection, - Thermodynamic and Chemical Engineering Models of CCHP FCSs,' discusses the physics and thermodynamic limits of CCHP FCSs.

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TYPE SAND Report YEAR 2010
DOIOSTI

Potential uses of a wireless network in physical security systems

Witzke, Edward L.

Many possible applications requiring or benefiting from a wireless network are available for bolstering physical security and awareness at high security installations or facilities. These enhancements are not always straightforward and may require careful analysis, selection, tuning, and implementation of wireless technologies. In this paper, an introduction to wireless networks and the task of enhancing physical security is first given. Next, numerous applications of a wireless network are brought forth. The technical issues that arise when using a wireless network to support these applications are then discussed. Finally, a summary is presented.

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TYPE Conference YEAR 2010
OSTI

Dielectric and ferroelectric analysis of nanoparticle/nanocrystalline barium titanate and PLZT

Diantonio, Christopher; Monson, Todd; Yang, Pin; Winter, Michael R.; Roesler, Alexander; Chavez, Thomas P.

Attractive for numerous technological applications, ferroelectronic oxides constitute an important class of multifunctional compounds. Intense experimental efforts have been made recently in synthesizing, processing and understanding ferroelectric nanostructures. This work will present the systematic characterization and optimization of barium titanate and lead lanthanum zirconate titanate nanoparticle based ceramics. The nanoparticles have been synthesized using several solution and pH-based synthesis processing routes and employed to fabricate polycrystalline ceramic and nanocomposite based components. The dielectric and ferroelectric properties of these various components have been gauged by impedance analysis and electromechanical response and will be discussed.

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TYPE Conference YEAR 2010
OSTI

A microsystems enabled field desorption source

Resnick, Paul; Hertz, Kristin

Technologies that have been developed for microelectromechanical systems (MEMS) have been applied to the fabrication of field desorption arrays. These techniques include the use of thick films for enhanced dielectric stand-off, as well as an integrated gate electrode. The increased complexity of MEMS fabrication provides enhanced design flexibility over traditional methods.

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TYPE Conference YEAR 2010
OSTI

Nano-crystalline PLZT for dielectric applications

Diantonio, Christopher; Monson, Todd; Roesler, Alexander; Huber, Dale L.; Chavez, Thomas P.; Stevens, Tyler E.

Nano-materials have shown unique crystallite-dependent properties that present distinct advantages for dielectric applications. PLZT is an excellent dielectric material used in several applications and may benefit crystallite engineering; however complex systems such as PLZT require well-controlled synthesis techniques. An aqueous based synthesis route has been developed, using standard precursor chemicals and scalable techniques to produce large batch sizes. The synthesis will be briefly covered, followed by a more in-depth discussion of incorporating nanocrystalline PLZT into a working device. Initial electrical properties will be presented illustrating the potential benefits and associated difficulties of working with PLZT nano-materials.

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TYPE Conference YEAR 2010
OSTI
Results 72601–72700 of 99,299
Results 72601–72700 of 99,299