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Andersen D.K.,University of Illinois at Urbana - Champaign | Andersen D.K.,Defense Nuclear Facilities Safety Board | Vakakis A.F.,University of Illinois at Urbana - Champaign | Bergman L.A.,University of Illinois at Urbana - Champaign
Conference Proceedings of the Society for Experimental Mechanics Series | Year: 2011

The influence of adding a geometrically nonlinear viscous damper to a system of coupled oscillators with essential nonlinear stiffness will be discussed. All nonlinear terms are restricted to the coupling terms between a linear oscillator and light attachment. We show that the addition of the nonlinear damper introduces dynamics not observed with linear damping. In fact, we find the surprising result that the nonlinear damper introduces new dynamics into the problem, and its effect on the dynamics is far from being purely parasitic - as one would expect in the case of weak linear viscous dissipation. Similar to essential nonlinear stiffness, geometrically nonlinear damping of the type considered in our work is physically realizable by means of linear viscous damping elements. Numerical work examining this problem will be discussed. ©2010 Society for Experimental Mechanics Inc.

Bamberger J.A.,Pacific Northwest National Laboratory | Minette M.J.,Pacific Northwest National Laboratory | Meyer P.A.,Defense Nuclear Facilities Safety Board | Fort J.A.,Pacific Northwest National Laboratory | Baer E.B.K.,Pacific Northwest National Laboratory
ASME 2011 International Mechanical Engineering Congress and Exposition, IMECE 2011 | Year: 2011

The Hanford Waste Treatment Plant (WTP) in Richland, Washington is applying pulse jet mixer (PJM) technology for slurry mixing applications requiring solids mixing, solids suspension, fluid blending, and release of gases generated by radiolysis and thermal processes. Experiments were conducted to investigate pulse jet mixer performance in two different experimental configurations: one using intermittent flow through the pulse tube with non-prototypic refill and the other with prototypic reciprocating flow. Models developed to predict the critical suspension velocity (UCS), cloud height, and concentration based on the intermittent flow data. This model under predicted the UCS condition for data obtained using prototypic reciprocating flow. When an adjustment to the settling velocity was incorporated into the model to address the effects of intermittent flow, the resulting reciprocating flow model more closely matched the experimental data. Copyright © 2011 by ASME.

Andersen D.,University of Illinois at Urbana - Champaign | Andersen D.,Defense Nuclear Facilities Safety Board | Starosvetsky Y.,University of Illinois at Urbana - Champaign | Mane M.,University of Illinois at Urbana - Champaign | And 5 more authors.
Physica D: Nonlinear Phenomena | Year: 2012

We study a peculiar damped nonlinear transition of a system of two coupled oscillators into a state of sustained nonlinear resonance scattering. This system consists of a grounded, weakly damped linear oscillator attached to a light, weakly damped oscillator with essential (nonlinearizable) stiffness nonlinearity of the third degree, and linear or nonlinear damping. We find that under specific forcing conditions the damped response of this system locks into a damped, non-resonant transition resembling continuous resonance scattering, whereby the transient damped dynamics closely follows an impulsive orbit manifold of the dynamics in the frequencyenergy plane. This manifold is formed by a countable infinity of periodic orbits and an uncountable infinity of quasi-periodic orbits of the underlying Hamiltonian system, with each of these orbits representing the response of the Hamiltonian system being initially at rest and forced by an impulse applied to the linear oscillator. Hence, the damped transitions reported here appear to lock in sustained resonance scattering from a countable infinity of periodic orbits along the impulsive orbit manifold. Such transitions represent an anti-resonance state, where the dynamics is farthest away from resonance. We conjecture that such transitions are only made possible by the essential (nonlinearizable) stiffness nonlinearity of the nonlinear attachment and cannot be realized in linearizable nonlinear dynamics where resonance captures prevent sustained resonance scattering. Our findings are supported by numerical, analytical and experimental results. © 2012 Elsevier B.V. All rights reserved.

Andersen D.,University of Illinois at Urbana - Champaign | Andersen D.,Defense Nuclear Facilities Safety Board | Starosvetsky Y.,University of Illinois at Urbana - Champaign | Vakakis A.,University of Illinois at Urbana - Champaign | Bergman L.,University of Illinois at Urbana - Champaign
Nonlinear Dynamics | Year: 2012

The dynamics of a system of coupled oscillators possessing strongly nonlinear stiffness and damping is examined. The system consists of a linear oscillator coupled to a strongly nonlinear, light attachment, where the nonlinear terms of the system are realized due to geometric effects. We show that the effects of nonlinear damping are far from being purely parasitic and introduce new dynamics when compared to the corresponding systems with linear damping. The dynamics is analyzed by performing a slow/fast decomposition leading to slow flows, which in turn are used to study transient instability caused by a bifurcation to 1:3 resonance capture. In addition, a new dynamical phenomenon of continuous resonance scattering is observed that is both persistent and prevalent for the case of the nonlinearly damped system: For certain moderate excitations, the transient dynamics "tracks" a manifold of impulsive orbits, in effect transitioning between multiple resonance captures over definitive frequency and energy ranges. Eventual bifurcation to 1:3 resonance capture generates the dynamic instability, which is manifested as a sudden burst of the response of the light attachment. Such instabilities that result in strong energy transfer indicate potential for various applications of nonlinear damping such as in vibration suppression and energy harvesting. © 2011 Springer Science+Business Media B.V.

Plaue J.W.,Lawrence Livermore National Laboratory | Plaue J.W.,University of Nevada, Las Vegas | Plaue J.W.,Defense Nuclear Facilities Safety Board | Klunder G.L.,Lawrence Livermore National Laboratory | And 2 more authors.
Journal of Radioanalytical and Nuclear Chemistry | Year: 2013

Near-infrared (NIR) reflectance spectroscopy was examined as a potential tool for the determination of forensic signatures indicative of the chemical process history of uranium oxides. The ability to determine the process history of nuclear materials is a desired, but underdeveloped, area of technical nuclear forensics. Application of the NIR technique potentially offers a quick and non-destructive tool to serve this need; however, few data have been published on the compounds of interest. The viability of NIR was investigated through the analysis of a combination of laboratory-derived and real-world uranium precipitates and oxides. A set of reference uranium materials was synthesized in the laboratory using the commonly encountered aqueous precipitation reactions for uranium ore concentration and chemical separation processes (ammonia, hydrogen peroxide, sodium hydroxide, ammonium carbonate, and magnesia). NIR spectra were taken on a range of samples heat treated in air between 85 and 750 C. X-ray diffraction patterns were also obtained to complement the NIR analysis with crystal phase information. Similar analyses were performed using a set of real-world samples, with process information obtained from the literature, to provide a comparison between materials synthesized in the laboratory and samples representative of industrial processes. © 2012 Akadémiai Kiadó, Budapest, Hungary.

Glover S.F.,Sandia National Laboratories | Foster P.J.,Defense Nuclear Facilities Safety Board | McDaniel D.H.,Sandia National Laboratories | White F.E.,SAIC | And 2 more authors.
Proceedings of the 2012 IEEE International Power Modulator and High Voltage Conference, IPMHVC 2012 | Year: 2012

Dynamic materials properties research at Sandia National Laboratories has resulted in research that is advancing capabilities in precision programmable pulsed power systems operating in multi-mega amp regimes. Programmable pulse shaping capabilities require the gas switches in these systems to perform over a large range of dynamic operating conditions. Runtime, jitter, and the number of channels formed are all impacted by the conditions of these switches at the time of trigger. This paper provides a model and analysis of a 200 kV gas switch designed for linear transformer drivers operating at percentages of self break ranging from 45% to 100%. This work expands on the research performed by T.H. Martin and S.I. Braginskii. © 2012 IEEE.

Glover S.F.,Sandia National Laboratories | White F.E.,SAIC | Pena G.E.,Sandia National Laboratories | Foster P.J.,Defense Nuclear Facilities Safety Board
Proceedings of the 2012 IEEE International Power Modulator and High Voltage Conference, IPMHVC 2012 | Year: 2012

Development of solid dielectric insulation concepts has enabled an ultra-low impedance high current driver concept called Genesis. A prototype demonstration called Protogen includes interfaces for up to twelve modules and can be operated in a repetitive mode to generate reliability data. Initial operation of Protogen is focusing on the integration of key solid dielectric concepts, dielectric lifetime, and integrated system performance. Multiple configurations of Protogen have already been tested demonstrating the flexibility of Genesis technology. This paper expands on previously published results paying particular attention to versatility, reliability, and modeling of the Protogen system. © 2012 IEEE.

Mossman K.L.,Defense Nuclear Facilities Safety Board
Health Physics | Year: 2014

Management of radiological risks typically encountered in environmental and occupational settings is challenging because of uncertainties in the magnitude of the risks and the benefits of risk reduction. In practice, radiation dose instead of risk is measured. However, the relationship between dose and risk is not straightforward because cancer (the major health effect of concern at low doses) is a disease of complexity. Risks at small doses (defined as less than 100 mSv) can never be known exactly because of the inherent uncertainties in cancer as a complex disease. Tumors are complex because of the nonlinear interactions that occur among tumor cells and between the tumor and its local tissue environment. This commentary reviews evidence for cancer complexity and what complexity means for radiation protection. A complexity view of cancer does not mean we must abandon our current system of protection. What it does mean is that complexity requires new ways of thinking about control of cancer - the ideas that cancers can occur without cause, cancers behave unpredictably, and calculated cancer risks following small doses of radiation are highly uncertain. © 2014 Health Physics Society.

Kassner M.E.,University of Southern California | Geantil P.,University of Southern California | Rosen R.S.,Defense Nuclear Facilities Safety Board
Journal of Engineering Materials and Technology, Transactions of the ASME | Year: 2011

This study reports the significant ambient temperature creep plasticity at stresses below the conventional 0.2% plastic strain off-set yield stress. This is partially due to the relatively high strain-rate sensitivity of 304 stainless steel. Cold-working significantly increases the creep resistance. Descriptive equations that predict low-stress creep plasticity, which are somewhat different than traditional creep-equation forms, are presented. © 2011 American Society of Mechanical Engineers.

Zutavern F.J.,Sandia National Laboratories | Glover S.F.,Sandia National Laboratories | Mancuso A.P.,Sandia National Laboratories | Foster P.J.,Defense Nuclear Facilities Safety Board | White F.E.,SAIC
Digest of Technical Papers-IEEE International Pulsed Power Conference | Year: 2013

Pulsed power gas switches operate under extreme conditions holding off voltages at millions of volts and greater, conducting currents at 100's of kiloamps, and can reliably trigger with less than 10ns of jitter at optimal operating conditions. However as Martin and Braginskii had noted the impedance of these switches is dynamic and a function of many parameters such as gas pressure, current, and the number of channels. In systems such as Protogen or Ursa Minor many gas switches are utilized to enable optimal performance and pulse shaping. A challenge with either system is that, if the switches are tightly coupled and one switch triggers early, then the fields on the second switch change dramatically and can move the second switch into a new operating regime that will result in a different dynamic resistance. This paper presents a least squares approach to extracting the Martin and Braginskii switch resistance with field dependent carrier recombination from measured data. © 2013 IEEE.

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